Metal–Organic Networks (MONs) are made by chemical molecules that contain metal ions and organic ligands. A crystalline porous solid called Metal–Organic Networks (MONs) is made up of a  Massively used compounds made by chemically like metal–organic network (MON) are thus made up of alloy ions/metallic ions and organic linkers. With the aid of the hydrothermal method, new MONs composed of zinc considered metal ions and benzene 3. Biography of MONs is their superficial alteration and as well as their particle control six division4. Devices with luminous properties could be created using 1. In reality,5. Additionally, the production processes of MONs related to zinc have lately been documented, and as well their toxicity, biological uses, and biocompatibility6. In modern chemistry, graph theory offers essential tools that depict chemical compounds' heats of formation, evaporation, flash points, temperatures, pressures, densities, and partition coefficients7. Zinc oxide is a white powder that is insoluble in water. Nanostructure of Zinc oxide Every heavenly body is a combination of several constituents that significantly contributes to the composition of the earth. The three-element hydrogen, oxygen and nitrogen are the most significant ones on the planet8, incorporating appropriate active material9, ion exchange10, creating composites using various materials11, modifying organic ligands, photosynthetic ligands, and improving the selectivity, sensitivity, and response times of biosensors.Yap et al.12 and Lin et al.13 presented the most current developments in precursors for a variety of nanostructures and MON-related applications, including lithium ion batteries, super capacitors, photocatalysis, electrocatalysis, and catalysts for the manufacture of fine chemicals. The field of modern chemistry can benefit from using graph theory to represent the physical and chemical characteristics of chemical compounds, such as their heats of formation and evaporation, flash points, melting points, boiling points, temperatures, pressures, densities, retention times in chromatography, tensions, and partition coefficients15. In order to investigate many characteristics of chemical compounds (such as the boiling point of paraffin), Wiener first developed the distance-based topological index (TI) in 1947. Gutman and Trinajsic's highly regarded first-degree-based TI was developed to test the chemical plausibility of the total π-electron energy of the chemical compounds .The zinc oxide and zinc silicate exhibit physicochemical characteristics including grafting active groups21. The details on other degree based molecular descriptors and structures are given in27. In 2021, the authors of28 computed the connection-based Zagreb indices such as first Zagreb connection index (ZCI), second ZCI, modified first ZCI, modified second ZCI, modified third ZCI, and modified fourth ZCI. We extended those results for other degree based topological indices as Modified version of second Zagreb index 29, Reciprocal Randic index 30, the Redefined Second Zagreb topological index 31 as well as the Redefined third Zagreb topological index 32 for MONs, namely Zinc oxide The Zagreb type indices contributed tremendously in the various fields which can be seen inHere, we initially present some significant definitions of the degree based molecular descriptors which will be useful to obtain the main results. In the whole study, we denote the adjacent vertices by 33,The molecular descriptor 34 as,The molecular descriptor 35,The molecular descriptor 36,The molecular descriptor 36,The molecular descriptor 31,The molecular descriptor 31,The molecular descriptor Let mentclass2pt{minimBased on the Definition Let mentclass2pt{minimBased on the Definition Let mentclass2pt{minimBased on the Definition Let mentclass2pt{minimBased on the Definition The following corollary is a direct consequent of Theorem Let mentclass2pt{minimLet mentclass2pt{minimBased on the Definition Let mentclass2pt{minimBased on the Definition Suppose entclass1pt{minimaBased on the Definition Suppose entclass1pt{minimaBased on the Definition Suppose entclass1pt{minimaBased on the Definition Suppose entclass1pt{minimaBased on the Definition The following corollary is a direct consequent of Theorem Suppose entclass1pt{minimaSuppose entclass1pt{minimaBased on the Definition Suppose entclass1pt{minimaConsidering Table n and the considered topological indices. As we increase n, the topological indices also increase. The comparative graphs of n. The increasing rate of In this part, we worked out all indices numerically and presented the results in the table below. From Figs. n and the considered topological indices. As we increase n, the topological indices also increase. Meanwhile, the comparative relationship of n. The increasing rate of From Figs. In this research, we calculated various recently discovered molecular descriptors for two separate metal–organic networks. The molecular descriptors which we considered are


In this work we use complex Lagrangian technique to obtain Noether-like operators and the associated conserved quantities of an Euler-Lagrange (EL) system. We show that the three new conserved quantities namely, Noether conserved quantity, Lie conserved quantity and Mei conserved quantity reported by Fang et al.  In this regard, the possession of one Lie point symmetry enables one to decrease the order of given ODE by one while two Lie point symmetries assist to reduce the order by two. On the other hand if an EL-equation admits a Noether symmetry, then it helps in double reduction of order as well as generating the related conserved quantity via Noether's theorem In a recent paper, Fang et al., In this letter, our aim is to construct conserved quantities of an EL-system considered in The structure of the forthcoming discussion is as follows: The next section is devoted to expressions on Noether-like operators and first integrals for system of equations. In section 2We commence with few basic terminologies on Noether-like operators and related expressions to work out first integrals (conservation laws) for two-dimensional EL-systems. We set a standard adaptable criterion to deduce conditions and theorems which will be used as means to determine useful operators and their effectiveness in the production of conserved quantities. For comprehensive details one is referred to read the papers Consider the following general system of second-order ODEsDefinition. For the optimal functions To proceed we assume that there exist a complex Lagrangian Noether-like theorem. The Noether-like operators 3After presenting key expressions of Noether-like operators and Noether-like theorem we deduce known important results on Lie, Noether and Mei conserved quantities of a two-dimensional EL-system We commence our discussion by observing that the system given in . FinallyFurthermore, it is generally believed that the availability of maximum numbers of invariant quantities often considered a first step towards finding the solution of underlying system. Remarkably, the elimination of 4We have addressed the problem of finding the Lie conserved quantity, Noether conserved quantity and Mei conserved quantity of a system of two linear second-order EL-equations by complex Lagrangian approach. The technique elegantly exploits Noether-like operators in order to establish the results as communicated in literature. In general, a linear system of EL-equations possesses maximum 8-dimensional algebra of Noether symmetries and have 8-first integrals. But here, we have seen that our technique yields 10 Noether-like operators and 10 first integrals. Among those 10 conserved quantities, some are the Lie conserved quantity, Mei conserved quantity and Noether conserved quantity which are reminiscent to those reported in M. Umar Farooq: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.Anum Naseem: Conceived and designed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data.C. Wafo Soh: Contributed reagents, materials, analysis tools or data.It is stated that all authors of the paper titled “Conserved quantities of Euler-Lagrange system via complex Lagrangian” have no conflict of interests whatsoever.


Though fracture is known complication of stenting, pseudoaneurysm asscoiated with stent fracture is an extremely rare complication. This has previoulsy been described to occur at least one or more years following initial stent placement. Here we present a case of multi-site stent fracture leading to two separate SFA pseudoaneurysms within one year of placement, successfully treated with covered stents.A 72-year-old male presented with severe claudication of his left lower extremity (Rutherford 3), found to have long segment SFA chronic total occlusion (CTO). Patient successfully underwent endovascular revascularization. Follow-up duplex ultrasound (US) at one year demonstrated a focus of severe in-stent restenosis (ISR). During repeat angiogram for treatment of the stenosis, stent fracture and pseudoaneurysm was seen in the distal SFA, which was treated successfully with a self-expanding covered stent. Additional stent fractures and pseudoanerusyms were subseuqently identified on follow-up, necessitating a third angiogram, and these were successfully repaired using overlapping covered stents, without further recurrence.Superficial femoral artery stent fractures leading to pseudoaneurysms are extremely rare, particularly within first year of stent placement. Endovascular repair with covered stents has proven to be an effective treatment option with decreased procedural morbidity compared to surgical repair. Peripheral artery disease (PAD) is a pathological accumulation of plaques in the arteries of the extremities and is reported to affect between 4.3% and 5.9% of all individuals aged 40 years or older and 14.5% of all individuals aged 70 and older , 15.Without successful revascularization, peripheral arterial disease can carry significant morbidity, with associated limb loss rate as high as 90% in one year . TreatmeA 72-year-old male patient with history of stroke, smoking, emphysema, atrial fibrillation, and hyperlipidemia, presented with severe claudication of the left lower extremity (Rutherford 3). Initial arterial duplex US demonstrated diffuse SFA occlusion. The patient underwent a left lower extremity angiogram with recanalization of the long segment left SFA CTO. During the procedure, multiple Everflex stents  were placed, spanning the entire SFA Fig. . PatientAt 1-month follow-up, patient demonstrated no recurrence of claudication symptoms; however, there was a new SFA pseudoaneurysm on duplex arterial US spanning from proximal to distal SFA, and demonstrating active flow into the pseudoaneurysm sac from the proximal SFA Fig. a. As sucAt the 9-month follow-up, left SFA pseudoaneurysms remained thrombosed without flow or enlargement, and clinically without signs of recurrence of symptoms of claudication. Endovascular revascularization for PAD often entails use of stents with the main objective of restoration and long-term preservation of the patency of the recanalized vessel . In thisOne specific complication associated with SFA stenting is stent fracture leading to restenosis, late clinical failure, and/or pseudoaneurysm development . The ratStent fractures can be divided into various categories for measurable classification. Various systems exist based on different markers such as number of strut fractures, strut fractures with or without deformity, gaps within the struts, and stent integrity , 14, 18.While SFA stent fractures leading to pseudoaneurysm are extremely rare, they typically occur two or more years after stent placement according to available case reports. In this case, the patient had a multiple overlapping bare-metal stents placed during initial intervention. Within 1 year, the patient was discovered to have two separate sites of wide neck pseudoaneurysm, in the proximal SFA and distal SFA, due to stent fracture. To our knowledge, this is the first case of multifocal fracture leading to multiple pseudoaneurysms of the SFA within a year of stent placement. Previously reported cases followed a similar timeline of events , however, they occurred at two, three, and five years , 12.Finally, stent fractures are often difficult to identify on angiographic evaluation alone. IVUS can address many of the limitations of angiography, providing accurate luminal dimensions, visualizations of diseased segments, stenosis, plaque size, stent deployment, and the mechanisms of device failure , 9. In tThis case demonstrates that while a typical stent fracture leading to pseudoaneurysm formation occurs after two years in the SFA, it can happen within a year of placement. As such, stent fracture should remain a concern even in the early post-operative period, and use of IVUS can help identify and treat this rare, but potentially critical complication. The use of covered stents to reestablish blood flow through the vessel while excluding extravasation or pseudoaneurysm growth has can be an effective endovascular treatment option, minimizing procedural morbidity compared to surgical repair.


Although a low-grade vascular tumor, Kaposi sarcoma (KS) can have mucosal, and visceral involvement. Additionally, disfiguring disseminated lesions can be seen in patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). KS may cause lymphatic obstruction leading to chronic lymphedema that further contributes to progressive cutaneous hypertrophy and severe disfigurement in the form of non-filarial elephantiasis nostras verrucosa (ENV).This report highlights a case of a 33-year-old male with AIDS who presented in acute respiratory distress with bilateral lower extremity nodular lesions. We confirmed a diagnosis of KS with overlying ENV via a multi-disciplinary approach. Collaboratively, we optimized our patient and observed adequate treatment response and overall improvement in clinical status.Our report emphasizes the importance of a multi-disciplinary approach in recognizing a rare presentation of ENV. Recognition of the disease and understanding the extent of the disease are crucial in preventing irreversible disease progression and allowing for maximum response. Kaposi sarcoma (KS) is a vascular tumor that develops through the infection of human herpesvirus 8 (HHV-8) . Risk faElephantiasis nostras verrucosa (ENV), a very rare presentation of severe disfigurement and lymphedema, may occur in AIDS-associated KS. Elephantiasis is typically known to be transmitted by mosquitoes carrying filarial nematodes, specifically, Wuchereria bancrofti, however, it can manifest in a patient with AIDS caused by lymphatic obstruction, leading to progressive cutaneous hypertrophy .We report a case of a 33-year-old male with known human immunodeficiency virus (HIV), who presented with acute respiratory distress with severe bilateral lower extremity disfigurement. Further workup revealed a rare case of non-filarial ENV in the setting of KS.A 33-year-old male presented to the emergency department (ED) with worsening shortness of breath, pelvic pain, and foul-smelling, brown-colored fluid leakage from both lower extremities. Past medical history (PMHx) was significant for HIV on highly active antiretroviral therapy (HAART), asthma, bipolar disorder, and KS. Chart review was significant for a CD4+ count of 148 with a viral load of 185,000 seven months prior to this hospital course. On admission, the patient’s CD4+ count was 97 with an undetectable viral load. Upon further history, the patient described the lower extremity lesions to be chronic, but progressively getting worse over the last few months and stated that the shortness of breath had started only one day ago, which prompted his visit. He also endorsed fever, chills, night sweats, and pleuritic chest pain. There were no other pertinent findings after a thorough review of all organ systems.On arrival, vitals were as follows: blood pressure 101/53 mmHg, heart rate 143 beats/minute, respiratory rate 34 breaths/minute, oxygen saturation 94% on room air, and his temperature was 102.4 F. Chest radiograph showed near-complete opacification of the right hemithorax. An emergency chest tube was placed by the ED team due to concern for impending tension pneumothorax. Thoracentesis yielded 2 liters of serosanguinous fluid, later found to be neutrophil predominant exudate.Upon further inspection and examination of the lower extremities, the patient was found to have multiple hyperpigmented, erythematous, and friable nodules showing a confluence of violaceous patches and plaques of varying sizes, swelling, and crusting with ulcerated and eroded areas along distal lower extremities resembling possible elephantiasis presentation Figure . There wOn day three of the hospital course, he developed worsening shortness of breath, requiring 15L of oxygen via a non-rebreather mask. A repeat chest radiograph at that time showed recurrent, right-sided pleural effusion with near-complete opacification of the right hemithorax Figure . A chestPleural fluid was successfully removed, and the patient underwent a video-assisted thoracoscopic surgery (VATS) with pleural biopsy. The pleural biopsy was negative for malignancy, suggesting that the pleural effusion was likely due to an infectious etiology which was treated empirically with ceftriaxone and doxycycline with clinical improvement. Subsequently, the patient developed a pneumothorax requiring a chest tube to suction. Unfortunately, the patient developed repeated pneumothoraces off suction, requiring the thoracic surgery team to perform pleurodesis.Lastly, we observed that the patient was persistently hyponatremic throughout the admission, although hemodynamically stable and asymptomatic Table . A complIn this case report, we described a patient with known HIV/AIDS and KS who had acute on chronic respiratory distress due to recurring pleural effusions likely secondary to infectious etiology and negative for malignancy. He also presented with active serosanguinous drainage from multiple hyperpigmented, erythematous, and friable nodules showing a confluence of violaceous patches and plaques of varying sizes, swelling, and crusting with ulcerated and eroded areas on both lower extremities leading to the suspicion of overlying ENV. Although rare, the clinical presentation alongside the biopsy of a lesion demonstrating papillomatosis with hyperkeratosis and dilated lymphatic channels confirmed the diagnosis of ENV in this patient with AIDS-associated KS. Typically, cutaneous lesions are considered progressive manifestations of KS; however, when coupled with lymphedema and severe disfigurement, non-filarial elephantiasis should be considered due to chronic lymphatic obstruction.Lymphoedema is due to the lymphatic load exceeding the transport capacity of the lymphatic system which causes fluid to accumulate in the interstitium. Due to impaired lymphatic drainage, the gravity-dependent area will enlarge, and hypertrophy can worsen with infection and inflammation . The accIn the case of KS herpesvirus, the exact mechanism by which lymphedema arises is unclear. KS herpesvirus has genetic homologs of cyclin D, G-protein-coupled protein, interleukin-6, and macrophage inflammatory protein-1 and -2 which can mimic and disrupt host cytokine signals . KS is aAnother possibility is that the cutaneous lesions in KS can cause lymphatic obstruction through external compression. Other research suggests that direct communications between cutaneous lesions and lymphatics alongside intermixing of blood and lymph may contribute to lymphedema in the setting of KS . FurtherThe treatment of ENV is challenging due to the lack of literature surrounding the management of elephantiasis. Ultimately, the goal is to treat the underlying cause of the lymphedema which in this case is KS. Supportive treatment of ENV includes elevation, massage, multilayer inelastic lymphedema bandaging, and compression stockings. More intensive therapy includes decongestive lymphatic therapy. Sequential pneumatic compression of extremity lymphedema is another possible treatment option. Still, it must be used early in the disease course as studies have shown that patients with fibrotic lymphedema respond poorly. Pharmacologic options include oral or topical retinoids as an adjunct to physiotherapy, diuretics, or coumarin (benzopyrone) which may produce limited success in reducing tissue volume, topical keratolytic  as well as deodorant powders to manage odor. Skin integrity must also be preserved to reduce the chance of bacterial or fungal infection which can be achieved through the use of emollients to prevent desiccation and breakdown of skin. If the skin does break down, topical antimicrobial agents may be considered to prevent life-threatening sepsis, especially in the context of an immunosuppressed patient such as the patient being presented. Lastly, surgical treatment should be considered after a medical intervention has already been attempted. Surgical debridement may provide comfort by reducing the verrucous lesions, and limb amputation can be considered for ENV that does not respond to treatment ,10. InteKS lesions correlated with lymphedema are considered a poor prognostic risk factor in the staging of KS in AIDS . ImproviIn this case report, we described a patient with known HIV/AIDS and KS who had acute on chronic respiratory distress due to recurring pleural effusions. He also presented with active serosanguinous drainage from large nodular lesions on both lower extremities leading to the suspicion of overlying ENV. Although rare, workup led to the diagnosis of ENV in this patient with AIDS-associated KS. Typically, cutaneous lesions are considered progressive manifestations of KS; however, when coupled with lymphedema and severe disfigurement, non-filarial elephantiasis should be considered due to chronic lymphatic obstruction. This case report demonstrates that although rare, ENV must be considered as a possible complication in a patient with AIDS-associated KS.Non-filarial elephantiasis, ENV, is very rare but can be found in a patient with known AIDS-associated KS. It occurs due to chronic lymphatic obstruction causing lymphedema and progressive cutaneous hypertrophy. This case report emphasizes the importance of a thorough physical exam, having a broad differential diagnosis, and workup for ENV in AIDS-associated KS patients who present with severe disfigurement.In patients who present with AIDS-associated KS, ENV should be assessed if lymphedema is present. Symptoms and complications of the low-grade vascular tumor can be severe in patients with HIV/AIDS with severe disfigurement, and mucosal and visceral involvement. ENV is a very rare presentation in a patient with KS, occurring due to chronic lymphedema.


Marlieke de Kraker discusses a systematic review and meta-analysis reporting the magnitude and consequences of bloodstream infections in low- and middle-income countries. Antimicrobial resistance (AMR) is central to a large number of the 17 Sustainable Development Goals (SDGs) that all 191 UN Member States have agreed to achieve by 2030. Since 2020, AMR has been explicitly included as an indicator in SDG 3 on “Good health and well-being”.PLoS Medicine’s Special Issue dedicated to AMR, Kasim Allel and colleagues present the results of a systematic review and meta-analysis, providing a comprehensive overview of published articles estimating the burden of AMR among bacteremic patients hospitalized in low- and middle-income countries (LMICs) [As part of  (LMICs) . The autIt has been estimated that AMR could be responsible for 1.3 to 5 million deaths globally, the upper limit of which would place AMR in the top three causes of death after ischemic heart disease, stroke, and chronic obstructive pulmonary disease . In thisThere is little high-quality, empirical data to support the notion that the largest burden of AMR can be found in LMICs. In a recent, prospective, observational study (MBIRA), including 8 hospitals from as many sub-Saharan African countries, Enterobacterales bloodstream infections greatly increased mortality, but the drug resistance profile of the Enterobacterales was not associated with an increased mortality risk . This maAt the moment, there are a number of studies ongoing in LMIC settings, like BARNARDS II , focusinThere is a pressing need for more high-quality, detailed data to better understand the burden of AMR in LMICs and beyond. However, this should not impede any investments to improve infection prevention and control, diagnostic and antimicrobial stewardship and supportive care for patients with serious bacterial infections in LMIC settings. These investments are urgently needed to improve patient outcomes and to make the SDGs attainable by 2030. The UN General Assembly High-Level meeting on AMR in September 2024 could play an important role by setting relevant targets and fostering collective action to reduce the global burden of drug-resistant and drug-susceptible infections.


Cyanobacteria form dense multicellular communities that experience transient conditions in terms of access to light and oxygen. These systems are productive but also undergo substantial biomass turnover through cell death, supplementing heightened heterotrophic respiration. Here we use metagenomics and metaproteomics to survey the molecular response of a mat-forming cyanobacterium undergoing mass cell lysis after exposure to dark and anoxic conditions. A lack of evidence for viral, bacterial, or eukaryotic antagonism contradicts commonly held beliefs on the causative agent for cyanobacterial death during dense growth. Instead, proteogenomics data indicated that lysis likely resulted from a genetically programmed response triggered by a failure to maintain osmotic pressure in the wake of severe energy limitation. Cyanobacterial DNA was rapidly degraded, yet cyanobacterial proteins remained abundant. A subset of proteins, including enzymes involved in amino acid metabolism, peptidases, toxin-antitoxin systems, and a potentially self-targeting CRISPR-Cas system, were upregulated upon lysis, indicating possible involvement in the programmed cell death response. We propose this natural form of cell death could provide new pathways for controlling harmful algal blooms and for sustainable bioproduct production. Eutrophication, resulting in expansion and prolongation of cyanobacterial mats and blooms, is expected to increase in frequency and severity with climate change and continuing industrialization , 2. DisiThe potential causes of cyanobacterial death include viral attack, predation, and programmed cell death , 8. CyanProgrammed cell death has been considerably less studied in prokaryotes compared to eukaryotes, but some hallmarks, including DNA fragmentation, protein degradation, breakdown of ribosomes and RNA, and the involvement of reactive oxygen species are known , 14. StuCandidatus Phormidium alkaliphilum” [Sodalinema alkaliphilum in GTDB version 214) in association with several other microbial members [To investigate the process of cell death in cyanobacteria, we used an alkaliphilic cyanobacterial consortium that was observed, during preliminary experiments, to undergo a mass lytic event midway through a 12-day dark and anoxic incubation. This cyanobacterial consortium was previously isolated from the productive benthic mats of an alkaline  soda lake , 22, andiphilum”   and supernatant (lysed and free-living) fractions every two days that were used for metagenomics and metaproteomics analysis. This data was then examined for signs of death-causing agents including viral attack, predation, and programmed cell death.Ca. P alkaliphilum, but only 3.6 % of this DNA remained after 6-8 days in the dark. After 12 days, DNA from Ca. P alkaliphilum was barely detected (0.15%) . Because acetate mainly accumulated before cyanobacterial lysis, Ca. P. alkaliphilum itself was likely responsible for its production [Initially, 72 % of the DNA extracted from the solid fraction originated from 5%) Fig. . A simil 12 Fig. . In cont 12 Fig.  and incr 12 Fig. , suggest 12 Fig.   and did not increase over the course of the incubation , suggesting that eukaryotic predation was not directly responsible for the collapse of the cyanobacterial population.The possibility of predation by a larger eukaryotic cell or an antagonistic bacterial species was evaluated using the metagenomics data. Eukaryotic ciliate grazers affiliated with ion Fig.  , the abundance of heterotrophic proteins did not increase significantly  , released cyanobacterial proteins persisted , and fermentation (producing acetate) stabilized after the lysis of the cyanobacteria . This might mean that the mainly aerobic consortium members did not have time to consume the released proteinaceous cyanobacterial lysate anaerobically. Taken together, our data did not point to a primary role of antagonistic bacteria in the cell lysis event.Provisional genomes, or metagenome-assembled genomes (MAGs), were acquired for the main cyanobacterial species, ota Fig. . The obs.2) Fig.  , and included detection of just over 2000 proteins, accounting for 52% of the predicted proteome of Ca. P. alkaliphilum , the post-lysis solids fraction (surviving cells and insoluble proteins of lysed cells), and the post-lysis supernatant fraction (soluble proteins of lysed cells) Fig. . These gThere were 52 proteins significantly more abundant in the solids fraction post-lysis. These proteins could have been upregulated in response to stress, or they could represent the proteome of surviving persister cells. The proteins upregulated in the solids fraction post-lysis included subunits of ATP synthase, cytochrome b6f, Photosystem I (PSI), and Photosynthetic Complex I . The latter is a homolog of Respiratory Complex I and is known to form a supercomplex with PSI . These cPrevious studies have identified an increase in cyclic electron flow in response to dark and anoxic conditions and have hypothesized that it could be a defensive strategy in preparation for the return of daylight and resumption of photosynthesis , or alteProteins that were statistically more abundant in the pre-lysis solids fraction, and downregulated before cell lysis, were largely involved in translation and transcription, and included ribosomal proteins, elongation factors, translation initiation factors, tRNA ligases, and RNA and DNA polymerases Fig. . AdditioCa. P. alkaliphilum genome, there are multiple toxin-antitoxin systems [Within the  systems . One par systems , 51 and  systems . Both of systems , 54. The systems , exertin systems , 55, 56. systems . This as systems , leadingIn conducting this differential abundance analysis, it was important to distinguish between intracellular proteins that are naturally released into the media during the lysis process and proteins that were statistically more abundant in the post-lysis supernatant fraction, indicating upregulation in lysing cells. We differentiated these two groups by distinguishing proteins that were enriched in both the solid pre-lysis and supernatant post-lysis fractions  from proteins that were enriched exclusively in the supernatant post-lysis fraction . There were 16 proteins that showed significant association with both the pre-lysis solids and post-lysis supernatant fractions. These proteins primarily included antenna-complex proteins such as phycobilisome linker proteins and allophycocyanin, as well as proteins involved in carbon metabolism like RuBisCO, phosphoglycerate kinase, and transketolase Fig. .Ca. P alkaliphilum  proteins were significantly enriched in the post-lysis supernatant fraction. A set of five Cas proteins forming a Type III CRISPR-Cas operon (accessions: 24366-24370) were highly expressed in the supernatant post-lysis. Expression of these Cas proteins increased over 10-fold between pre- and post-lysis in the supernatant Fig. . Becauselum Fig. , it seemlum Fig. . In canoProteins associated with the supernatant post-lysis fraction also included several peptidases and proteases, as well as over 30 proteins involved in amino acid metabolism Fig. . This in+) and lower (0.25 M Na+) salinity.Could energy depletion in the dark have triggered the observed potential programmed cell death response? If cell lysis was triggered by energy depletion, increasing salinity would result in a need for higher cellular maintenance energy to cope with elevated osmotic pressure and would consequently deplete energy reserves sooner. This hypothesis was tested by performing independent dark and anoxic incubations of the cyanobacterial consortium at higher , compared to the original incubation at 0.5 M Na+ (6.6 mg/mL)  Fig. . In the y 5 Fig. , and thePhormidium and Nodosilinea decreased rapidly and became essentially negligible two cm below the sediment surface. Rapid turnover of cyanobacterial biomass could explain the previously observed steep sulfide gradients [Dethiobacter [Desulfonatronovibrio [Evidence for similar cyanobacterial lysis occurring in situ was investigated using 30 cm cores of cyanobacterial mats and underlying sediment from the culture source, alkaline Lake Goodenough (Canada) Fig. . 16S rRNradients . Sulfideiobacter , 66, andnovibrio   [Ca. P. alkaliphilum accounted for up to 2.5% of the DNA, and 7.5% of the protein (MAG C5 in that study). The cyanobacterial consortium was grown in continuous light (200 µmol photons/(m2·s)) in 10 L stirred glass vessels. The growth medium was previously described [2 gas to create an anoxic headspace and then placed at room temperature (21 °C) in the dark. At 0, 2, 4, 6, 8, 10, and 12 days after the start of the incubation, two sacrificial samples were taken. To each sample, 5 mL of pH 7, phosphate-buffered saline solution was added and then the sample was centrifuged for 10 min at 4500 rpm, to separate biomass and supernatant.An alkaliphilic cyanobacterial consortium enrichment culture containing a single, abundant, cyanobacteria species, ion 214) , 24, wasion 214) , where Cescribed  and contFor biomass pellets, the ash-free dry weight of each sample was measured using NREL laboratory analytical procedures protocol . For theDNA was extracted directly from soda lake sediment and incubated solid samples using the Fast DNA Extraction Kit for Soil . For the incubation of supernatant samples, 250 µL of the sample was used for each extraction. The extraction protocol of the manufacturer was followed, but additional purification steps were performed with 5.5 M guanidine thiocyanate . For supGeitlerinema” by Silva and shared 100% sequence identity with the 16S rRNA gene from Ca. P. alkaliphilum. For consistency, this OTU was relabelled “Phormidium” in Fig. Amplicon sequencing and library preparation of the DNA sediment samples were performed as previously described  using prAll biomass samples, and supernatant samples from days 2, 4, 6, 8, and 12 were prepared for metagenomic sequencing as previously described . Brieflyhttps://jgi.doe.gov/data-and-tools/bbtools/). Quality control consisted of trimming reads to 150 bp, trimming off adapter sequences, filtering out contaminants, such as the PhiX adapter, and clipping off low-quality ends, all as previously described [Raw, paired-end Illumina reads were filtered for quality using BBDuk (escribed . Paired-escribed . Separatescribed . To increscribed . Only coescribed  was usedhttps://sourceforge.net/projects/bbmap/). Mapping results were summarized using the script, “jgi_summarize_bam_contig_depths”, part of the MetaBat package [Binning of assembled reads into metagenome-assembled-genomes (MAGs) was completed using MetaBat2 version 2.12.1 . The bin package . After b package  in conju package  was used package .The relative abundance of individual MAGs in each metagenome was calculated by mapping quality-controlled raw reads from each sample onto the contigs of each MAG as well as the dereplicated contigs that remained unbinned. Again, BBMap (minid = 0.98) was used for this. Unbinned contigs were dereplicated using cd-hit-2d . In thisEmirge assembly) was used to obtain full-length 16S and 18S ribosomal RNA (rRNA) gene sequences and their sequencing depth from the metagenomes [The program phyloFlash v3.3 , using a 75 cm × 75 µm analytical column and analyzed in a Qexactive Plus hybrid quadrupole-Orbitrap mass spectrometer  as previously described . A totalhttp://www.thegpm.org/crap/). The final database contained 454,164 proteins and preserved the assignment of predicted proteins to their respective MAGs from the metagenomes. This enabled the calculation of proteome contribution for each MAG. For protein identification MS/MS spectra were searched against the database using the Sequest HT node in Proteome Discoverer version 2.2.0.388  as described previously [The database used for protein identification was manually created using the predicted and annotated proteins from the binned and unbinned metagenomic sequences. Cd-hit was used to remove redundant sequences from the database using an identity threshold of 95% , giving eviously . Only prRelative protein abundances were estimated using the normalized spectral abundance factor (NSAF) . MAG abuCa. P. alkaliphilum proteomics data was divided into pre and post lysis groupings. The supernatant pre lysis grouping included days 0 and 2, and the supernatant post lysis grouping included days 4–12. The solids pre lysis grouping included days 0, 2, and 4, and the solids post lysis grouping included days 6–12. These groupings were chosen based on NMDS clustering . The sediment cores were taken from 3 different locations within each lake  for 2 h. Cores were then horizontally sliced into 2 cm disks using a Dremel Multi-Max MM50 oscillating saw  at the lowest speed, used to reduce blade contact with the sediment. The blade was sterilized with 70% ethanol before each core section was sampled. To avoid the potential risk of contamination from the core liner or during sectioning, sediment in contact with the core liner was removed, and the inner core was transferred to a 50 mL tube, sealed, and stored at −20 °C. The sediment from each disk was subsampled for DNA extraction and stored at −80 °C.2 gas up to atmospheric pressure to create anoxic conditions. These serum bottles were then incubated in the dark at room temperature for eight days. Every day, two bottles were removed from the incubation and analysed for phycocyanin as described above. Electron microscopy was conducted as described previously [The dark and anoxic incubation of the cyanobacterial consortium was repeated using dewatered biomass with different concentrations of sodium. Initially, biomass obtained after growth was first dewatered and then gently washed with deionized water to remove the salts. This step was repeated five times to ensure that all the salts were removed. The washed biomass was then separated into three aliquots. Each aliquot was washed with sodium carbonate solution with varied concentrations . Then, approximately 2 g of wet paste from each aliquot was placed in sterile serum bottles. The headspace in the serum bottles was vacuumed and filled with Neviously  without Supplementary MaterialSupplementary Table 1Supplementary Table 2Supplementary Table 3Supplementary Data 1


A clear trend from over 0.7 to 0.5 in the Mark–Houwink exponent and a decrease in Rg/Rh from 1.7 to 1.0 point to the formation of nanogels, more rigid and less permeable than the starting coils. Changes in the coil contraction factor (g′ = [η]irradiated/[η]linear) as a function of the radical density revealed the existence of two modes in intramolecular crosslinking, the initial one  where the compactness of products changes strongly with progressing crosslinking and a second one where further compacting is suppressed by the lower flexibility of the partially crosslinked chain segments. This indicates a transition from soft, still internally crosslinkable nanogels to more rigid structures, less prone to further intramolecular loop formation. Our findings provide means for the tailored design of new PAA nanomaterials.In this paper, a state-of-the-art multi-detection gel permeation chromatography/size exclusion chromatography (GPC/SEC) system including multi-angle laser light scattering (MALLS) is applied to monitor radiation-induced synthesis of internally crosslinked nanostructures from poly(acrylic acid) (PAA). The aim is to demonstrate that this modern tool yields a more detailed picture of reaction mechanism and product structure than the techniques used to date. The prevailing intramolecular crosslinking narrows the molecular weight distribution from M Macroscopic polymer-based hydrogels and their nanosized analogues, nanogels, can be synthesized using a variety of methods. The approach studied in this work, that is, utilizing ionizing radiation to induce crosslinking in an additive-free aqueous polymer solution, is an interesting alternative both to the classical chemical synthesis of hydrogels ,6,7,8,9 Ionizing radiation is particularly useful to synthesize polymer products for medicine. This is due to the fact that radiation processing is fast and easily controllable, requires no additional compounds such as initiators, catalysts or crosslinkers, hence obtained products can be readily chemically pure. Moreover, in some implemented technologies, such as production of hydrogel wound dressings based on radiation-crosslinked poly(N-vinylpyrrolidone) (PVP), radiation synthesis and sterilization can be accomplished in one step, thus reducing the number of required operations ,22,23.Radiation-synthesized nanogels, extensively tested as nanocarriers of drugs, genes and radioisotopes ,29,30,31−12 s) and the abundant generation of reactive species, such as hydroxyl radicals, hydrogen atoms and solvated electrons ). Based on the changes in parameters, such as the Mark–Houwink equation’s  of a relatively low molecular weight (M sample) , which i sample) . A detai2O, Cat. No. 416002-500ML, Lot STBG9347, Sigma Aldrich, Steinheim, Germany) was used without further purification. Polymer concentrations are expressed as mmol of monomer units/L (mM). Perchloric acid  and sodium perchlorate (NaClO4·H2O) were procured from Sigma-Aldrich . Anhydrous di-sodium hydrogen phosphate (Na2HPO4) and 1 M standard aqueous solution of sodium hydroxide (NaOH) were purchased from POCH S.A. . The samples were filtered with Minisart NML cellulose acetate syringe filters of 0.45 µm pore size . The eluent for GPC/SEC was filtered through filter paper . Alanine pellets for dosimetry were purchased from Bruker . Throughout all the experiments, TKA-Micropure  filtered water was used.Linear poly(acrylic acid) (PAA) with a nominal molecular weight of 250 kDa (35 wt.% solution in H4 to protonate the carboxylic groups of polymer and thus compact the coils. Irradiation run for each solution was conducted at ambient temperature in a deoxygenated closed-loop system (circulation velocity 1 mL s−1), under continuous argon saturation. A schematic representation of the irradiation setup is depicted in Polymer irradiation was performed by a pulsed beam of high-energy electrons in a preparative pulse radiolysis regime, as described previously , with slShort (4 μs) pulses of 6 MeV electrons at a frequency of 0.5 Hz were produced by the linear accelerator ELU-6 , and the dose absorbed by a looping sample aliquot (0.7 mL in quartz cuvette) in a single pulse was ca. 1 kGy. The exact average dose per pulse was determined with alanine dosimetry ) for each experiment. Each cycle consisted of a specific number of pulses, which ensured the irradiation of the whole circulating volume with a specific dose (as specified in the data graphs). Following the completed cycle, 50 mL of the sample irradiated with a specific dose was withdrawn from the solution reservoir. Subsequently, the system was re-deoxygenated for at least 10 min and the next cycle started. Five cycles of irradiation per run were performed, yielding 6 samples per single solution . After irradiation was completed, the samples were refrigerated until further analysis.w), radius of gyration (Rg) and intrinsic viscosity ([η]), all samples were analyzed using gel permeation chromatography. The GPC/SEC system was provided by Testa Analytical Solutions  and consisted of an isocratic pump, automatic injector, a set of 2 separation columns in a thermostatic column oven, as well as three detectors: multi-angle laser light scattering detector (MALLS) , differential refractive index (DRI) and differential pressure viscosity detector, the last two combined in a single assembly with the common sample path . Separation columns were supplied by PSS Polymer Standards Service GmbH ; Suprema Lux analytical Linear XL column  with Suprema Lux analytical SDV precolumn (to remove dust or large-sized aggregates) were used in all experiments. As the eluent, 0.1 M Na2HPO4 in water (pH 9.4)  of all products were calculated. Changes in these parameters as a function of total absorbed dose are presented in Based on the obtained chromatograms, the weight-average molecular weight (Mg of our PAA in that solvent [Changes in the weight-average molecular weight and radius of gyration accompanying the radiation-induced synthesis of nanogels based on poly(acrylic acid) were reported previously by our group for PAA of a higher molecular weight (500–900 kDa) than that studied in this work . It was  solvent , was ca.w and Rg (w/Mn is higher than 2 (which was the case in this paper), it is expected to contribute to making the distribution more narrow. Another effect that may contribute to the narrowing of the molecular weight distribution is that, when scission occurs, one of the resulting fragments bears a free radical and the other one a double bond. More double bonds may be formed by the disproportionation of radicals, which competes with crosslinking. As a result, mid-chain and terminal radicals can be added to double bonds. Therefore, the fragments formed by degradation may become again linked to other macromolecules, and thus they do not appear as short chains in GPC/SEC. It should be noted, however, that this description is strictly true for the initial stages of irradiation; as explained below, at high total absorbed doses, other factors, such as steric hindrance and chain stiffness, come into play.The application of GPC/SEC with a triple detection system as described in w and Rg A,B, but w and Rg . The obsw (ca. 130 kDa), we obtained no direct proof of the latter process  remained qualitatively the same with the increase in the dose, there was no clear trend in the magnitude of these effects as a function of the concentration. Nevertheless, data points for all concentrations converge when viscosity changes are correlated with radical density along the chains (see discussion below). A similar effect (increase in the molecular weight during irradiation of solutions of different concentrations) was observed previously during the synthesis of nanogels using the initial high-molecular-weight PAA [In our previous works on high-molecular-weight PAA (500–900 kDa) , at the  process A, albeit process B. One shight PAA  or PVP [ight PAA .g) and hydrodynamic radius (Rh) obtained by means of static and dynamic light scattering, respectively). According to Burchard [g and Rh were determined in this paper in different solvents; see the Experimental Procedure Section), and the error bars are relatively large, it is clear that, while for the unirradiated sample the value (1.8) is characteristic for solutions of flexible, random coils of moderate polydispersity [The formation of highly intramolecularly crosslinked macromolecules, i.e., nanogels, was also confirmed by the calculation of the ρ-parameter  soft nanogels are formed, what happens when irradiation is continued and what are the structure and properties of the product obtained using a high dose. Is the efficiency of intramolecular crosslinking constant or does it decrease when the product becomes highly crosslinked?An answer can be obtained with a more detailed analysis of the GPC/SEC data, especially by the incorporation/utilization of light scattering and viscosity measurements.2HPO4 aqueous solution is a thermodynamically good solvent for poly(acrylic acid). The values obtained for all irradiated solutions are presented in In The α-parameter is a scalar value that is related to the stiffness of the polymer chains. In general, despite some scatter in the data, it is clear that, for all concentrations, the α values for the irradiated solutions are lower than the starting value of 0.71; for the lower concentrations, a clear decreasing trend is observed. For instance, for the 17.5 mM solution, with the increase in the absorbed dose, the α-parameter decreases to 0.5. This indicates an increase in segment–segment interactions, as this value is characteristic for the Flory theta solvent, pointing to a compact structure in contrast to an expanded, loose coil, corresponding to an α value of 0.7–0.8. An interesting phenomenon was observed for the 25 mM PAA solution. Regardless of irradiation, the α value is almost constant (around 0.6), which may be a result of polymer–polymer interactions in the solution of the highest concentration.This shows that, from a thermodynamical point of view, by changing the polymer concentration and the absorbed dose, one can influence the crosslink density, which determines chain stiffness and interactions between the segments of macromolecules. But how to distinguish between different products of irradiation, i.e., loosely crosslinked nanogels and more tight structures, closer to spherical polymer nanoparticles with a low solvent permeability? An explanation was already provided through the calculation of the ρ-parameter . Gel per•OH self-combination was applied) to the number of repeating units  are presented. One can see that the values of the intrinsic viscosity for different poly(acrylic acid) concentrations, but for an equal ratio between the number of radicals and the number of repeating units, are similar. An analogous behavior was observed through the Monte Carlo simulations of the intermolecular recombination of radicals [In radicals . That inThe results shown in It is noteworthy that, despite the fact that our products indeed resemble hyperbranched structures, it is disputable whether they meet the classical definition of branched polymers. The character of hyperbranched coils is particularly pronounced when considering the properties and chromatographic separation behavior of our irradiated PAA, since in comparison to linear chains, we see clearly lowered hydrodynamic volume leading to a shift in the peaks on the GPC chromatograms. However, according to IUPAC, chain branching occurs when, in the reaction, there is a net increase in the number of reactive species . The recg/Rh ratio. While the accuracy of some of the obtained results may still need to be refined and some issues, such as the polymer concentration dependence of the Mw and coil density, need to be further clarified, the general picture emerging from Mw, Rg and viscosity measurements is in line with what has been previously published for PAA of somewhat higher starting molecular weights than our sample. Moreover, applying multi-detection GPC/SEC allowed us to follow the reacting system in more detail than it was possible before, by studying new important properties, which have not been accessible to date. First of all, we could follow changes in molecular weight distribution. High-molecular-weight chains, bearing several radicals after an electron pulse, undergo mainly intramolecular crosslinking, with only limited increase in their average molecular weight. On the other hand, short chains, on which only single radicals are generated, undergo mainly intermolecular crosslinking, leading to a pronounced increase in molecular weight. As a result, the molecular weight distribution becomes narrower, the Mw/Mn parameter being reduced (for 17.5 mM solution) from 3.0 to 1.6. The measurements of molecular weight and viscosity for each analyzed fraction of non-irradiated and irradiated samples allowed the following of the changes in the Mark–Houwink exponent, which is over 0.7 for linear PAA but drops to ca. 0.5 upon irradiation, indicating a substantial structural change from a free coil to much more rigid and less water-permeable, internally crosslinked particle. The detailed analysis of the coil contraction factor as a function of the average number of radicals per monomer unit revealed the existence of two modes of internal crosslinking. The first mode  is where the compactness of products changes relatively strongly with progressing crosslinking. It is followed by another mode, when further progress in making the chain more compact is weaker due to the lower flexibility of the  chain segments. This observation indicates a transition, at a certain ratio of the number of radicals to the number of monomer units, from relatively soft and still internally crosslinkable nanogels to more rigid structures, less prone to undergo further internal loop formation. Summing up, the multi-detection GPC/SEC system with MALLS is a welcome and valuable new tool for studying complex processes of free-radical reactions in polymer solutions. It can facilitate the tailored design of new polymer nanomaterials with the desired physicochemical properties for future biomedical applications.The nanoscale radiation engineering of polymers plays an emerging role in contemporary nanoscience. Fast, cost-effective, safe and environmentally friendly processes, initiated with reactive species derived from water radiolysis, yield materials with very promising properties. Still, we need novel analytical methods for a deeper understanding of those processes, to learn how to use them in our favor to obtain the desired products, tailored for the particular applications, such as medicine. The results presented in this work demonstrate the usefulness and advantages of applying a state-of-the-art multi-detection gel permeation chromatography/size exclusion chromatography (GPC/SEC) system, including multi-angle laser light scattering (MALLS), for studying the radiation-induced synthesis of polymer-based nanogels. Firstly, we showed that the results obtained by this technique for a model polymer, PAA, are in line with previous knowledge on the pulsed radiolysis of this polymer in dilute acidic solutions, intramolecular crosslinking being the main process leading to the formation of compact, internally crosslinked macromolecules, with intermolecular crosslinking and possibly chain scission as the side reactions. We successfully reproduced most of the main tendencies demonstrated before, i.e., increase in molecular weight with absorbed dose with no parallel rise in the radius of gyration (leading to the increase in coil density), and decrease in viscosity and in the R


R⊥ for magnetization perpendicular to the electric current direction. In this review, this century-old phenomenon is reviewed both from the perspective of materials and physical mechanisms involved. More recently, this effect has also been identified and studied in antiferromagnets. To date, sensors based on the anisotropic magnetoresistance (AMR) effect are widely used in different fields, such as the automotive industry, aerospace or in biomedical imaging.Resistance of certain (conductive and otherwise isotropic) ferromagnets turns out to exhibit anisotropy with respect to the direction of magnetization:  Magnetoresistances (MRs) encompass a wide range of phenomena and in this review, we only focus on situations where the anisotropy of R is caused by magnetic order. By large part, we will discuss ferromagnets (FMs) where such anisotropic magnetoresistance (AMR) has been explored extensively but only a few reviews exist and the most popular McGuire & Potter   and [111] , and their large difference implies that, in terms of equation (80Co20)86Fe14 reach K2 there is an increase leading to a sign change to positive values with increasing Fe and Co  found both negative and positive AMR, depending on the total number of valence electrons Nv. If that number was between 28.2 and 30.3, a negative AMR was reported, otherwise a positive. According to band structure calculations, in between NV of 28.2 and 30.3, it corresponds to half-metallicity [2FexMnx1−Si: Here the AMR is negative for x ≤ 0.6 and positive for x ≥ 0.8, which is explained by a transition from minority conduction to majority conduction and thus interpreted as a possible sign for half-metallicity as well [2FeSi, the AMR ratio was determined for different samples distinguished by their annealing temperature: above 2(Fe − Mn)Si, Co2(Fe − Mn)(Al − Si) and Co2(Fe − Mn)Al was reported to be approximately Investigation of AMR in Coallicity  as can bs before . The AMRw and RT .Figure 2MnGa [2FeAl [2MnSi [ϕ) and cos (2ϕ) contributions (ϕ being some angle of rotation). The higher-order symmetries make AMR in these materials much more complex as e.g. in simple transition metals, where normally only twofold symmetries are found. An example of such a rather complex signal in Heusler compounds can be found in While the majority of studies focus on AMR ratio and sign, the symmetry of these compounds is also a puzzling topic: in Co2MnGa , Co2FeAla [2FeAl  and Co2Ml [2MnSi , the AMRper se have a cubic crystal structure, but in thin films the substrate usually introduces a small tetragonal distortion. Still, despite this explanation being plausible, the complex temperature dependence of the twofold and fourfold contributions [The fourfold contributions in these signals are too strong to be ascribed to MCA solely. In a theoretical study by Kokado & Tsunoda , it was ibutions ,12 asks Nv. These explanations are rather diverging and not allowing for a consistent conclusion. On a microscopic level, however, the various studies can be summarized quite well: as long as the compounds are having a half-metallic character/showing minority conduction, the AMR is negative. In the case of majority conduction and metals not fully polarized on the Fermi level, the AMR becomes positive. It appears to be the case that the Co-based Heuslers investigated here are all by default  half-metallic, but can be all tuned to lose this half-metallic character . The theoretical model used to explain it was developed by Kokado & Tsunoda [In conclusion, a couple of observations can be made for AMR in Co-based Heusler alloys: firstly, the AMR ratio is generally decreasing with increasing temperature, as expected. Secondly, the AMR is very small, often well below 1% and only in some specific configurations  it reaches up to approximately equation  is usual Tsunoda . It is nNon-Co-based Heusler and semi-Heusler compounds. Just as with transition metal alloys, Heusler materials [2Mnx1−FexGe. The latter is a ferromagnet for x = 1 (no Mn) and an antiferromagnet for x = 0 (no Fe). For x = 0.5 an anisotropy in the MR is observed with a MR of x = 0 and x = 1 no MR was found [aterials  span a vaterials  or Ru2Mnas found .. 3.5Introduction. A two-dimensional electron gas (2DEG) can form on various interfaces: the surface of liquid helium, classical semiconductor heterostructures or certain transition metal oxide interfaces (TMOI). The textbook example of such a TMOI is a SrTiO3/LaAlO3 (STO/LAO) interface, where the two perovskites individually are non-magnetic insulators [3) at stronger magnetic fields can be taken as an argument that the latter are not dominant , and . The fo 2d,e in ) can be AMR in LAO/STO. On a qualitative level, the AMR of a 2DEG at the LAO/STO interface can exhibit two types of behaviour, see T and high carrier densities n. A positive and twofold AMR was found for temperatures T > 35 K, while for lower T and higher n, a negative AMR and higher orders up to sixfold symmetry in (111) and (110) interfaces [terfaces ,139–141 n [B-field strength [T high-n phase (approx. n) [B = 9 T [The absolute value of the AMR ratio is not the major point of discussion and should be taken with maximum caution, due to its strong dependence on temperature , currentn ), B-fielstrength ,142 and tical n) . A largeIn calculations, the AMR is frequently linked to a strong anisotropy of the FS as exemplified in n and high-n regimes [n regime [tg2-orbitals and broken inversion symmetry are generally a central part in the modelling of LAO/STO interfaces [The electronic structure at the FS is different between the low- regimes ,143 and  regimes ,143. Theterfaces ,141–143.Other materials. Apart from the much-investigated LAO/STO interface, 2DEGs at a TMOI can be found in other material combinations, for example LVO/KTO (LaVO3/KTaO3) [3 (the last-mentioned system stands out by being non-polar without strain). AMR was only studied in the first two examples; sometimes, anisotropic data is shown [3/KTaO3) , LVO/STO3/KTaO3) , LTO/STO3/KTaO3)  and CZO/3/KTaO3)  interfacis shown  (longituIn low-temperature measurements in (001)-interfaces of LVO/KTO  and LVO/. 3.6The previous five sections of this section were devoted to the material classes showing the most important and remarkable results in the field of AMR. This is not nearly a complete picture of the universe of AMR. In the following section, we are going to discuss briefly the results of several other material classes.Fe-based alloys. Apart from iron–cobalt and iron–nickel alloys which were discussed already in §3.1, Berger et al. [et al. [r et al.  investig [et al.  below in0.8Ga0.2 it was found that the AMR is twofold and for in-plane (out-of-plane) configuration at a magnetic field of 500 mT (8 T) showed negative (positive) AMR. Interestingly, with increasing temperature the AMR is constant (decreasing). The AMR ratio is slightly larger than 0.1% (between ca 0.2% and 0.5%). The perfect twofold-shaped AMR curves were interpreted as a sign that saturation magnetization was reached [In Fe reached .TC depending on the Cr concentration are listed in tab. 1 of [ferromagnetic anisotropy of resistivity instead of AMR. The rapid decrease of the AMR ratio is accompanied by a drop of TC, from 778 K for 2% concentration to 48 K at 21% concentration [Properties of NiFeCr alloys such as AMR ratio, low-temperature resistivity and ab. 1 of . A maximOther alloys or structures involving transition metals. The AMR of Co–Pd alloys was investigated in [x and its temperature dependence was analysed in terms of Parker plots . A maxir et al. . It can et al. [J| = 43 meV for the coupling between magnetic moments and highly conductive s-electrons.Calculated values of the AMR ratio and the residual resistivity of Co–Pd and Co–Pt alloys as a function of the cobalt-concentration are shown in figs. 5 and 3 of Ebert et al. , respectet al. . Note thet al.  and the The in-plane and out-of-plane AMR of nickel sandwiched by platinum was experimentally investigated and the symmetry of the AMR discussed . The nicThe symmetry of AMR in ultrathin Fe-monolayers on a GaAs interface changed depending on the number of monolayers. While for eight monolayers, a fourfold component was dominant, with decreasing number of monolayers to six and four, the fourfold component decreased. This was attributed to a change of symmetry due to transitioning from bulk-like to interface-like symmetry .4N and the derived materialsThe perovskite iron nitride Fe CuFe3N [4N [transverse AMR  [4 in the matrix of Fe-doped GaN also exhibits AMR [s CuFe3N  and Mn4NFe3N [4N . For theFe3N [4N ,151,152  or PHE) . FeN4 inbits AMR .4N below 30 K [transverse AMR of Fe4N and in Mn4N the fourfold component is dominant for low temperatures.In all samples, a fourfold component of the AMR was found, for example in in-plane Felow 30 K , and it 4N (in-plane) and in CuFe3N remain negative, while Fe4N (transverse) and Mn4N show positive AMR for temperatures above approximately 50 and 100 K, respectively. Low temperature AMR ratios for Fe4N and Mn4N scatter between approximately γ′ − CuFe3N, low-temperature values in the range of −0.067 to All samples show negative AMR at low temperatures. The AMR in Fey −0.75%  and −7% 75% [−7%  in iron 75% [−7% ). While 75% [−7% . In the sd-models [4 this was suggested to be due to anisotropic thermal compression [In iron and manganese nitride, the decrease of the AMR coefficients with increasing temperature show a kink at about 50 K, changing from rapid to moderate decrease. No explanation was given. The results were discussed in the framework of d-models . Negativpression .Some more perovskites. Metallic SrRuO3 exhibits negative MR [ative MR  as expecative MR . The AMRr effect . Howeverr effect . AMR andectively , implyin3 shows AMR for temperatures below 20 K, which was interpreted as a sign of a possible ferromagnetic ordering emerging at low temperatures induced by local structure distortion due to lattice strain. The presented data were close to a twofold AMR. More precisely, the fitting process yielded AMR ∝ cos (1.75ϕ) [The non-magnetic SrIrO (1.75ϕ) . The rel3 does not show such behaviour and the here investigated film is a thin film on a SrTiO3 substrate [Interestingly, bulk SrIOubstrate . In the Manganites form a large class of perovskite materials ranging from the more common antiferromagnets such as CaMnO3 [XaYbMnO3, where X and Y are a trivalent and divalent cation, respectively, with their respective concentrations a and b [Y is either Ca [0.51Sr0.49MnO3 [0.5Ca0.5MnO3 [3 (BTO) [s CaMnO3  to FMs  [0.4Sr0.6MnO3 sample on a STO substrate [0.7Ca0.3MnO3 films [The AMR is usually reported to be twofold; however, also fourfold AMR was reported. While the fourfold symmetry was reported to be robust in La3 (LCMO) , it onlyubstrate . Other substrate  is clearO3 films . In the O3 films , it was et al. [The sign of the AMR is in most cases predominantly negative. However, some studies report a sign change of the AMR as a function of temperature ,167,169,et al. , a 80 nm0.3Pr0.4Ca0.3MnO3 at its peak value approximately below 150 K [figure 15a. AMR values were reported as highly sensitive to e.g. sample composition, type of substrates [Magnitudes of the AMR ratio are scattered between approximately 0.1% in LCMO  and ‘colow 150 K  on a STObstrates —and thusbstrates . An exam0.4Sr0.6MnO3 [0.51Sr0.49MnO3 sample [In an absolute majority of the studies, the low-temperature AMR increased with increasing temperature in clear contrast to the usual behaviour and peaked just below the metal–insulator transition temperature. Above this temperature, the AMR ratio decreased rapidly. The microscopic mechanism of AMR in these materials is distinct from conventional FMs  . These tr0.6MnO3  and in a3 sample , while tThe explanation for the characteristic behaviour is usually linked to strain resulting in orbital deformation via the Jahn–Teller effect ,167,169.2 is well understood (see §3.3).It is worth noting that the ‘colossal’ peak values of AMR can be usually observed in the vicinity of the MIT-temperature, where also the CMR effect occurs. Thus, explanations of these large AMR values have to be taken with some caution as neither the CMR effect is fully understood. In the latter case mainly due to a lack of quantitative theory describing the MIT and the subsequent insulating phase, which in our judgement might be problematic in the description of the AMR as well understood. In contrast, MIT in EuTeOther conductive oxides. In Fe3O4 (magnetite), AMR was used to refute predicted half-metallicity [0.3Fe2.7O4 shows a strong fourfold component as well [2. Here, angle-dependent spin-torque ferromagnetic resonance measurements (ST-FMR) in fig. 3b,d of [allicity , and latallicity . The ori as well . Another 3b,d of  resembleTMDC-based magnetic compounds. Being non-magnetic themselves, some transition-metal dichalcogenides (TMDCs) allow for insertion of magnetic atoms as reviewed in the introduction of [ction of  and ferr1/4NbS2, thus Mn-inserted NbS2, ferromagnetism occurs below its Curie temperature of TC = 104 K, while for higher temperatures it is paramagnetic. Furthermore, first-principle calculations suggest a pressure-induced transition to a AFM state. Experiments were conducted at various temperatures for fields up to 9 T. The comparison LMR and TMR measurements allow to conclude that there is no AMR in the paramagnetic state, while differences in LMR and TMR in the FM state for large enough fields show AMR of up to approximately T = 2 K [In Mn T = 2 K .0.28TaS2 is ferromagnetic below TC = 68.8 K. Angle-dependent MR measurements confirm the existence of AMR, which is slightly larger than 10% for the saturated state at T = 10 K for B = 8 T. MR of this compound is about 100 times larger than for the similar Fe0.25TaS2 [1/3TaS2. Next to FM order (Tc ≈ 70 K), measurements indicated the existence of cluster spin glass at low temperatures. AMR, which can be calculated by comparing LMR and TMR, is in a similar order of magnitude as for the previous compound of Fe0.28TaS2 [Fe0.25TaS2 . Similar0.28TaS2 .1/3NbS2 is identified as a chiral helimagnet below the critical temperature TC = 111 K. Both AMR and PHE show a twofold behaviour of less than 5S8, magnetization studies suggest an antiferromagnetic ordering around TN ≈ 27 K. Low-temperatures AMR measurements show a twofold AMR of up to Contrasting the simpler types of magnetic order of the previously mentioned materials, Cragnitude . Lastly,agnitude .. 4There is a broad range of opportunities to exploit the AMR and also to go beyond magnetization-controlled DC resistance. In the following, we will shortly discuss both industrial and scientific applications of this effect, ranging from the well-known AMR sensors used in a variety of fields to subtle techniques for the detection of spin relaxation in FMs. Related phenomena in optics and thermoelectricity will be mentioned as well.. 4.1scientific applications discussed here and the results of numerous AMR experiments in the previous section is the direction of reasoning: while the measured AMR values and their symmetry were used to reach conclusions about the inner workings of the AMR, now the AMR as an effect is known and so the measured values are used to detect another quantity, mostly the magnetization direction.The difference between magnetometry. This is the main application of AMR in a scientific context and a few examples are given in the following paragraph. This section also summarizes a variety of other applications of AMR measurements and theory.Since AMR gives the dependence of the resistivity on the magnetization direction, it can be used as a means of et al. [2Se3 and permalloy [A new ferromagnetic resonance (FMR) method using AMR was developed by Fang et al. . There, et al. . Comparaet al.  in the het al.  and RT sermalloy .In another context, the AC susceptibility of thin films of Co, Ni and nickel alloys was determined by voltage measurements. The expression for the susceptibility (eq. 6 in ) was derAnd lastly, magnetization reversal was studied by AMR (amongst other means) in nickel nanowires . Howeversd-scattering, which has been mentioned in many positions in this work already. Usually, theoretical predictions of the strength of sd-scattering lead to predictions about the AMR. The opposite is, however, also possible: a very small non-crystalline AMR of 0.001% was used to argue that sd-scattering is repressed, the electron carriers and Fermi level reside in the conduction band and the main scattering process is s-s-scattering [A frequently invoked concept of the AMR theory is the attering ,186.sd-scattering is governing AMR, its reverse process the d → s electron scattering is involved in spin relaxation. A spin-relaxation theory suitable for nickel- and cobalt-based alloys based on the theory of AMR of Campbell, Fert and Jaoul [While the nd Jaoul ,187 was nd Jaoul .The angular dependence of AMR was used in various occasions: first, in quantifying the current-induced Rashba fields in LAO/STO heterostructures and investigating their dependence on applied magnetic field and on electric field modulation . The LAO0.73La0.27FeAs2 single crystals, where it was argued that the FS is quasi-two-dimensional [Secondly, the signals of inverse spin Hall effect (ISHE) and AMR are typically mixed and thus knowledge about AMR is crucial to quantify the spin-Hall angle correctly. In ,191 methensional .. 4.2This section attempts to give a short overview of AMR-related research outside the mainstream, such as the investigation of AMR in non-collinear systems (see §4.2.3) where no single spin direction can be defined as in FMs (net magnetization) or collinear antiferromagnets (Néel vector); as well as discussion of similar effects which can partly make use of AMR terminology as such its thermoelectrical counterpart, the AMTP discussed in §4.2.2 below.. 4.2.1σ(ω) and so is its anisotropy. It is meaningful to divide the following discussion into low and higher frequencies. Given the typical scattering rates 1/τ in electrically conducting materials, the former means terahertz while the latter spans the visible range and beyond. In the following paragraph, we discuss AMR in the terahertz regime.This review focuses on AMR in the DC regime. Conductivity is, nevertheless, a function of frequency σ(ω) is dominated by intraband contributions which are usually well approximated by the Drude peak, σ(ω) ∝ (1 − iωτ)−1, where τ is the transport relaxation time. It is then possible to split [ω-independent term B happens to be a function of the intrinsic AMR and the ω-dependent part of the extrinsic AMR, the ac-AMR offers a possibility for experimentally distinguish these two quantities (see §§1.1 and 3.1) [50Fe50 [The special aspect of the terahertz range is that to split ,193 AMR and 3.1) . In this [50Fe50  and perm [50Fe50 ,193 were [50Fe50 ,193.ωτ ≫ 1), the focus turns to magneto-optical effects which are even in magnetization, such as the Voigt effect or its analogy in reflection (see fig. 2 in that reference for an overview) as counterparts to AMR in the DC-limit. Spectral measurements then provide information about the valence band structure: iron [Beyond the THz range, interband terms become important, see eq. B6 in . At thesre: iron , re: iron  or Heuslre: iron . Going ere: iron  involves. 4.2.2L11 = σ/e that may depend on magnetization direction [L12 tensor correspond to the anomalous Nernst effect , and the AMR (in L11) has the AMTP as its counterpart in L12. Magnetoanisotropy of all these coefficients can be anticipated [The AMTP is the thermoelectric counterpart of the AMR. Among linear response coefficientsirection . Off-diaicipated ; they aricipated .L12 are challenging due to possible unwanted thermoelectric contributions which hardly can be averaged out [Literature is sparse since measurements and calculations are both challenging. The measurements of 2MnGa [2MnGa only crystalline and non-crystalline AMTP components up to the second order were confirmed, higher-order components have been identified in As. In both cases, AMR and AMTP components were not directly related. More examples of AMTP studies in As can be found in sec. III-D-2 of the review by Jungwirth et al. [Quantitative studies based on phenomenological symmetry-based models analogous to the approach presented in §2.1 are conducted in Co2MnGa  and in  in polycrystalline Ni nanowires [et al. [Concerning the anowires  for a raanowires ,187 was  [et al. .. 4.2.3spin up and spin down) which are aligned parallel to each other and allow for the definition of a SSA (the Néel vector); practical differences between these two cases (compare the SW1 and SW2 models discussed in §1.5) are small nevertheless. Collinear AFMs alone, however, do not exploit the set of zero-net-magnetization systems to the fullest. In the case of non-collinear antiferromagnets, all magnetic moments do point in the same plane; however, it is not possible to define a SSA as the Néel vector. An example is magnetic ordering on a Kagome lattice in Mn3Sn [For a long time, the AMR was only associated with FMs. However, the discovery of AMR in collinear antiferromagnets, as described in §3.3, demonstrated that AMR can also occur in other magnetically ordered materials. Collinear AFM can have only two MSLs  for a symmetric  is influenced by a well-defined parameter. For non-collinear magnets, the cleanest way of defining such anisotropy is by assuming that this parameter is an external magnetic field , which is also the most practical from the point of view of an experiment ,207. Thi. 4.2.4In the context of anisotropic magnetotransport, research focuses mostly on the diffusive regime in bulk systems. In the following, we wish to mention several phenomena outside this realm. First, AMR in the ballistic transport regime is discussed, followed by a quick look at TAMR and AMR in topological insulators.Transport in the diffusive regime is dominated by scattering, described by the mean-free path of the carrier. When the sample size becomes smaller than the mean-free path we are talking of the ballistic regime: carriers are only scattered at the boundaries of the sample and can otherwise travel unhindered. Ballistic transport is often related to one-dimensional structures such as nanowires. It is possible to have AMR in this regime, which is subsequently either called ballistic AMR [quantized AMR (QAMR) because of its stepwise character [et al. [stic AMR  (BAMR) oharacter . The BAMharacter . It was haracter ,210. Theharacter  and ironharacter ,210 have [et al.  at this The dependence of ballistic AMR on an ideal infinite monoatomic iron wire was compared with influences of domain walls and contacts, both of which can alter the transport properties significantly . And lasTunnelling AMR can be understood as a crossover of AMR, where the anisotropy, thus changing of resistivity with magnetization direction, is important; and the tunnelling magnetoresistance (TMR) [et al. [et al. [ce (TMR) ,214, whi [et al.  carried  [et al. . Recentl [et al. , found t [et al. . The TAMet al. [2Te3, which is a FM up to 8 K, exhibits a giant AMR of more than 120% in a rotation from out-of-plane to in-plane. This is because, for an out-of-plane field, a magnetic gap opens for the surface states (quantum AHE), but when the field is in-plane, surface states are restored [Kandala et al.  found threstored .magnon AMR (MAMR) and a magnon PHE were reported [Beyond charge transport, an analogy of AMR in transport of magnons in an ferromagnetic insulator has been observed. Measurements of reported  in a serreported . The MAMproximity-induced AMR was measured in bilayers consisting of a non-magnetic conductor and a magnetic insulator. As conductors served Pt [2Se3 [et al. [Moreover, in various cases, a erved Pt , Pd [220Pt [2Se3 ,222. ThePt [2Se3 ,220,222, [et al. . The AMR [et al. . Also fo2Se3-bilayers, the magnetic field was rotated in an out-of-plane rotation plane. Positive AMR  by the proximity of a material with different symmetry.. 4.3To date, the AMR effect is widely exploited in sensors as a direction-sensitive magnetometry probe to obtain quantities such as absolute position or rotation speed –225.Important is the usage in the automotive industry , in biomρ0 ow noise . Wide tependence ,229,233,pendence . Commonlpendence ,238. TheIn application-based publications, anisotropic MR is considered as non-crystalline AMR ,225,237 Arguably the best-known applications of AMR fall into the realm of magnetic memories. Early magnetoresistive random access memories (MRAM) were based on the effect, yet it is much smaller in magnitude than GMR which eventually prevailed . Modern . 5Magnetotransport in solids is a vast and mature field. In this review, we focus only on a small part of it, namely its anisotropy related to magnetic order. AMR usually refers to this phenomenon, albeit occasionally orbital effects are also included (and these are not covered in this review). Two characteristic features of magnetism are helpful to this end: remanence and coercivity. Unlike ordinary MR which just happens to be anisotropic, the AMR can usually be observed as a spontaneous effect even at zero field; on the other hand, well above coercive field, MR traces should run in parallel regardless of the experimental configuration . Microscopically, the AMR can either originate from anisotropic scattering or band structure deformation (related to magnetic order) which is analogous to the extrinsic and intrinsic mechanism of the AHE. This analogy is not very deep, however, as it can be exemplified with the intrinsic AMR which is unrelated to Berry curvature of Bloch states.The phenomenological understanding of the AMR is based on symmetry analysis of the resistivity tensor, and the basic distinction of non-crystalline (equation ) and cryAMR has been investigated in a vast range of materials, starting with the simple and elemental ferromagnets Co, Fe and Ni and their alloys, of which especially permalloy has received great attention due to its favourable properties for applications. Other materials in which significant investigations have been carried out include the dilute magnetic semiconductor As, antiferromagnets as CuMnAs and MnTe, Co-based Heusler alloys, two-dimensional electron gases on LAO/STO interfaces, manganites and other perovskites. Many more materials have received at least a little attention. The magnitude, sign, symmetry and inner mechanisms of AMR in these vastly different material classes vary heavily.While the AHE has attracted considerably more attention than AMR in fundamental research, the situation is quite the opposite in commercial applications. Contrary to AHE, the AMR has already made it to the market-ready stage in the niche of various sensors still widely used to date  and also in the past in magnetic memories. Scientific applications of AMR, such as a means to determine magnetization direction in situations where other methods fail, have also become important. More work is needed, however, to close the gap between real-world applications and the large body of fundamental research that has been carried out on AMR over the last 165 years.


The World Health Organization estimates that 9 out of 10 people worldwide breathe air containing high levels of pollutants. Long-term and chronic exposure to high concentrations of air pollutants is associated with deleterious effects on vital organs, including increased inflammation in the lungs, oxidative stress in the heart and disruption of the blood–brain barrier. For this reason, in an effort to find an association between exposure to pollutants and the toxicological effects observable on human health, an online resource collecting and characterizing in detail pollutant molecules could be helpful to investigate their properties and mechanisms of action. We developed a database, APDB, collecting air-pollutant-related data from different online resources, in particular, molecules from the US Environmental Protection Agency, their associated targets and bioassays found in the PubChem chemical repository and their computed molecular descriptors and quantum mechanics properties. A web interface allows (i) to browse data by category, (ii) to navigate the database by querying molecules and targets and (iii) to visualize and download molecule and target structures as well as computed descriptors and similarities. The desired data can be freely exported in textual/tabular format and the whole database in SQL format.Database URLhttp://apdb.di.univr.it Chronic exposure to air pollution appears to cause deleterious effects on human health, affecting lung and heart functions, as well as generating alterations in brain cognitive functions that may potentially increase risk factors for neurodegenerative disorders such as dementia, Alzheimer’s and Parkinson’s diseases ]. Supplied chemical species include six air pollutants identified as ‘criteria’, namely ground-level ozone, PM, carbon monoxide, lead, sulphur dioxide and nitrogen dioxide. The EPA, in regulating emissions of hazardous air pollutants, provided an original list later modified through rule-making to include 188 hazardous air pollutants, which are classified as ‘HAPS’ in SPECIATE [https://www.epa.gov/haps/initial-list-hazardous-air-pollutants-modifications ].A comprehensive list of air pollutants is provided by the Environmental Protection Agency (EPA), in particular, the EPA has released the SPECIATE database, a curated repository of speciation profiles of air pollution sources that describes the chemical composition of organic gas, particulate matter (PM) and other pollutants emitted by these sources [https://wwwn.cdc.gov/TSP/index.aspx ], the Risk Assessment Information System [https://rais.ornl.gov/tools/tox_profiles.html ], containing toxicity profiles of different chemical species, and the Hydrosil International Ltd website [https://hydrosilintl.com/resources/pollutants ], a leading producer of odour, water, hazardous air pollutants and volatile organic compounds’ control filtration products.Other sources of air pollution information are the Agency for Toxic Substances and Disease Registry Portal, collecting details on adverse health effects due to exposure to hazardous substances [http://www.structuralchemistry.org/pcsb/capp_cdf.php ].Molecular structures of air pollutants can be represented in the most recognized chemical-data file formats, e.g. the SDF format (Structure Data Format), a formatted ASCII file widely used to store and exchange comprehensive information about the chemical structure of molecules, including their atom types, bond types, 3D coordinates and other relevant properties, and the SMILES format (Simplified Molecular-Input Line-Entry System), a compact ASCII string that encodes the connectivity of atoms in a molecule in a standardized manner which makes it particularly suitable for database searching , which describe the tendency of a molecule to behave as a nucleophile or an electrophile, are the most known. QM methods accurately describe the behaviour of the electrons in atoms and molecules based on the Schrödinger equation that governs the wave function representing all the properties, e.g. momentum, time, position and spin, of a particle in a quantum system [http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/schr.html ].Molecules can be characterized through a wide range of structural and physicochemical properties, also called molecular descriptors. Descriptors can be calculated starting from two-dimensional (2D) structures  and froab initio quantum chemistry programme that applies to both organic and inorganic chemistry, is used to calculate molecular properties  and QM properties . PaDEL instead is used to compute physicochemical properties, a wide range of 2D and 3D molecular descriptors and fingerprints. The fingerprint of small molecules is a binary or a count string representation that can be fragment-based, encoding the presence or absence of specific structural features or patterns, e.g. MACCS (Molecular ACCess System) keys  keys  or the Eem) keys , or hashhttps://www.daylight.com/dayhtml/doc/theory/theory.finger.html ]. Depending on the type of descriptor, several measures can be used to derive similar molecules. For example, for numeric vectors (e.g. 2D autocorrelation indices or E-state indices), the similarity is the complement of the normalized Euclidean distance or just the cosine similarity between them  collected molecular data in APDB, (ii) computed quantum properties, (iii) calculated molecular descriptors and fingerprints, (iv) derived molecular similarity, (v) implementation of the web interface and (vi) overview of the database. The section ‘Utility and discussion’ describes case studies and discusses obtained results. The section ‘Conclusion’ summarizes key points and gives suggestions on possible applications.https://www.epa.gov/air-emissions-modeling/speciate-0 ] that also incorporates the list of hazardous air pollutants [https://www.epa.gov/haps/initial-list-hazardous-air-pollutants-modifications ] classified as ‘HAPS’. SPECIATE 5.1 (June 2020) is released both in Microsoft Access® and in the SPECIATE Data Browser.The APDB database contains a collection of air pollutant molecules from the US EPA website, which provides the list of SPECIATE data , while additional molecular properties, descriptors and fingerprints were calculated with the PaDEL-Descriptor software ], which generates an energy-minimized and accurate 3D representation of a molecule, i.e. its most stable conformation, allowing to avoid issues with the molecular structures and geometries. We applied the OPLS4 molecular mechanics force field ] reports information about the ionization state, formal charge and added hydrogen. To improve the readability, the details of the output fields are given in The computation of quantum mechanical descriptors comprises two main tasks: (I) geometry optimization and (II) single-point energy calculation. Canonical SMILES were imported in Maestro in order to clean them up and check the correctness of atom connectivity, bond orders and desalting, using the LigPrep module ; the substructure fingerprint that represents the presence or count of 307 SMARTS patterns describing atomic and bond properties [https://www.daylight.com/dayhtml/doc/theory/theory.smarts.html ]; the Klekota–Roth fingerprint, a 4860-bit array that describes the presence or count of chemical substructures defined by Klekota and Roth , while not similar molecules are those with a low similarity (e.g. <0.46). Through a chi-squared test, we found that the association between being similar or not similar and having common targets was statistically significant. Moreover, we observed that the group of similar molecules had slightly higher odds of having common targets than not similar molecules.APDB is a relational database implemented in PostgreSQL with a web application developed using Python (version 3.10.4) and Flask (version 2.1.2) . The froRDKit  was usedThe main APDB interface modules are Home, Statistics and Downloads/Contacts. These allow (i) to navigate the database by searching for molecules, targets and bioassays, descriptors and similarities; (ii) to visualize data statistics and (iii) to download data.Through the Home section, the user is directed to subsequent pages where one can browse molecules, targets and bioassays, descriptors and similarities.Molecular annotations: Molecules are specified by using the chemical name, CID, CAS, InChIKey, canonical SMILES and molecular formula from PubChem. Molecule structures can be filtered by clicking on one periodic table element. By pressing the download button, users can obtain a CSV file with the whole table or with the selected items from the column checkboxes, the periodic table or the search form. Molecules can be searched by all their listed identifiers. By clicking on a CID entry, users are redirected to the panel of similar molecules.Targets and bioassays: Bioassays are specified through the assay ID, associated CID, activity value in µm, activity name, assay name, assay type and PubMed ID. Targets are inserted by their GenInfo Identifier, gene ID, symbol and UniProtKB. By pressing the download button, users can obtain a CSV file with the whole table or with the selected items from the column checkboxes or the search form. Targets can be searched by all their listed identifiers. By clicking on a UniProtKB entry, users are redirected to the target panel containing information on the searched target. If present, the optimized PDB file generated with 3Dmol.js can be visualized and downloaded through the ‘PDB’ button; otherwise, users can download and explore the predicted protein structure on the AlphaFold page. Molecules associated with the searched target can be downloaded as a CSV file by pressing on the download icon. By clicking on a CID entry, users are redirected to the panel of similar molecules.Molecular descriptors: Descriptors are illustrated through an interactive radar chart representing the distribution of the IDF weights of all classes of fingerprints bits and counts and a scatter plot matrix with the first five principal components of molecular descriptors and quantum properties. By pressing on the download icon, users can obtain a CSV file with the corresponding descriptor table.Molecular similarities: Similarity spaces are illustrated through an interactive scatter plot of k-means clusters projected to 3D with t-distributed Stochastic Neighbor Embedding (t-SNE) ( (t-SNE) . The leg (t-SNE)  shows moThe Statistics section illustrates some interactive charts on data in APDB. A pie plot shows the percentage of organic and inorganic molecules. A histogram plot represents the count of molecules with a specific number of targets. A set of histograms shows the distribution of similar molecules at different similarity thresholds. A table describes the number of entries in APDB.Through the ‘Documentation’ section, the user can have an overview of the data contained in the APDB and a quick guide to the main sections and utilities.In the ‘Downloads/Contacts’ section, the whole database can be dumped as a compressed archive .zip or in .sql format (except for molecular descriptors and fingerprints which can be downloaded in .csv format from the dedicated page). Search results  can be downloaded in .csv format through the corresponding ‘Download’ buttons.The user can easily access and browse APDB molecular information through the appropriate sections and search for a query molecule to get similar compounds, known biological targets and related chemical features. For each chemical entity, the results represent the specific contribution of each chemical space in computing similar molecules as described in the section ‘The molecular similarity’.We selected the most representative molecules to illustrate the features and usability of APDB, e.g. 2-(2-hydroxypropoxy)propan-1-ol, 1-methyl-4-nitronaphthalene for organic and HAp, and phosgene for inorganic compounds . These f1-Methyl-4-nitronaphthalene is a nitro derivative of naphthalene, classified as a nitroaromatic compound which in turn has been used as an intermediate in the synthesis of other organic compounds, such as dyes, pesticides and pharmaceuticals . Indeed,Both compounds are not widely studied and their analysis can potentially shed light on negative effects on human life.HAp is a naturally occurring mineral form of calcium phosphate. It is the main mineral component of bones and teeth in living organisms and is insoluble in water and organic solvents. HAp has a number of unique properties that make it useful in a variety of industrial and medical applications. Due to its chemical similarity to the mineral component of bone, it has been used as a bone substitute material in orthopaedic and dental applications. It is also used as a coating material on metal implants to promote bone growth and improve the bonding between the implant and the surrounding bone.Phosgene is a poisonous and colourless gas primarily used as a constituent in many pharmaceutical and organic industries. Once inhaled, it produces a dose-dependent toxic effect by acylating several enzymes related to energy metabolism, which in turn causes a breakdown of the blood–air barrier resulting in the clinical manifestation of pulmonary oedema .Analysing the results of case studies queries, it is noteworthy how every chemical space of similarity shows interesting and complementary similarity aspects between molecules. Thus, the consultation and comparison between different chemical spaces offer the user the possibility to analyse similarities from different points of view. Fingerprints spaces will give back molecules containing similar fragments within the chemical structure, whereas molecular descriptors and quantum mechanical descriptors will propose molecules with structural and reactivity similarities.For example, analysis of phosgene results  shows caFor the other inorganic compound chosen as a case study, HAp, it is really interesting to see how three different spaces suggest the same prioritized compound as similar, chrysotile asbestos (CID 25 477), based on different aspects of their reactivity. It is known that these two minerals share a similar toxicity profile, due to their reactivity and capability to interact with inflammation cascade (e.g. NLRP3 inflammasome activation) . The sechttps://cameochemicals.noaa.gov/browse/react ] as alcohols and polyols or ethers, act as acute and chronic toxicants to different targets (Results for organic compounds enlighten other interesting aspects of molecular similarity. The 2-(2-hydroxypropoxy)propan-1-ol (CID 32 881) was found to be similar to 1,1ʹ-oxydi-2-propanol (CID 8087) and 1-ethoxy-2-propanol (CID 15 287). These compounds, classified in the ‘CAMEO Chemical Reactivity Classification’ [ targets . In thisFor the fourth case study, 1-methyl-4-nitronaphthalene, the chemical spaces found the same molecules as the most similar, 1-methyl-5-nitronaphthalene and 1-methyl-6-nitronaphthalene (CID: 93496 and 86258), two structural isomers. It confirms again the importance of the similarity tool offering a molecule set that is similar in structural patterns and mechanism of action. Interestingly, in this case, molecular descriptors and quantum properties did not recognize the 1-methyl-6-nitronaphthalene as the most similar to the query molecule, and it is probably due to different reactivity to oxidation and subsequent toxic mechanism led by the methyl position .APDB is an essential resource that improves our knowledge of the existing pollutant molecules, providing an in-depth insight into their physicochemical, structural and quantum properties. The collection of pollutant molecular structures together with all the chemical characteristics provided in APDB offers scientists a unique resource for a wide view of the biochemical aspects of pollutant toxicity mechanisms. As a matter of fact, APDB is the first publicly available online database offering a complete chemical and biological annotation of air pollutants.Moreover, derived similarities can be explored to identify similar molecules, then infer similar mechanisms of action and study potential synergistic effects in disease pathways . As prevbaad046_SuppClick here for additional data file.