In order to obtain reliable values of nonlinear coefficients, two criteria for selecting a reference compound were proposed: (1) it should possess a band gap close to that of the sample to be measured and (2) it should possess a refractive index close to that of the sample to be measured. This work might shed light on improvements in accuracy that can be made for effective NLO coefficients obtained using the Kurtz–Perry method.The accurate evaluation of nonlinear optical (NLO) coefficient, the main parameter affecting light conversion efficiency, plays a crucial role in the development of NLO materials. The Kurtz–Perry powder technique can evaluate second-harmonic generation (SHG) intensity in pristine powder form, saving a significant amount of time and energy in the preliminary screening of materials. However, the Kurtz–Perry method has recently been subject to some controversy due to the limitations of the Kurtz–Perry theory and the oversimplified experimental operation. Therefore, it is very meaningful to revisit and develop the Kurtz–Perry technique. In this work, on the basis of introducing the light scattering effect into the original Kurtz–Perry theory, the theoretical expression of second-harmonic generation intensity with respect to band gap and refractive index are analyzed. In addition, the reference-dependent SHG measurements were carried out on polycrystalline LiB Genecrystals ,19,20. Hcrystals ,25,26,27ij using powder crystal monolayers [The Kurtz–Perry powder technique was first proposed by S. K. Kurtz and T. T. Perry in 1968 . This tenolayers ,41. Undo2 [2O4 (β-BBO), KH2PO4 (KDP), LiB3O5 (LBO), KTiOPO4 (KTP), AgGaS2 (AGS), AgGaSe2 (AGSe), and ZnGeP2 (ZGP) [mid- and far-infrared regions. The linear and nonlinear optical properties of these crystals are summarized in 4S7 (BGS), BaGa4Se7 (BGSe), ZGP, and LBO. In addition, on the basis of introducing the light scattering effect into the original Kurtz–Perry theory, the theoretical expressions of band gap and refractive index on SHG intensity were derived, and two criteria for selecting appropriate reference materials have been proposed.Recently, Clark et al. demonstrated that the use of commercial and homemade grades of the same polycrystalline reference can result in significant deviations in the NLO coefficients of LiInSe2 . HoweverP2 (ZGP) ,45,46,47eff values of these five compounds were then determined one by one through Equation (15). It is worth noting that the effective NLO coefficients obtained by using AGS as a reference in this work are quite different from those reported in the literature. The other five substances were then selected as the reference material, and the effective NLO coefficients of these materials were also obtained. The results of this work and those mentioned in the literature are summarized in The powder SHG responses of LBO, AGQ , ZGP, and BGQ  with particle sizes of 20–50 μm were explored using a 2090 nm laser as the fundamental light, and the results are illustrated in Therefore, we consider that the reason for the above huge difference is the selection of mismatched reference materials. In general, the six substances mentioned above were usually selected as references because they are commercially available and are well known. Based on the above discussion, we believe that an appropriate reference material is necessary for obtaining accurate SHG coefficients using the Kurtz–Perry method. Thereby, what conditions should an appropriate reference satisfy? Herein, the SHG intensities measured by the Kurtz–Perry method for powder samples were theoretically analyzed.x and y dimensions are far greater than the sample thickness (L) and the main beam incident along the z-axis can be described by a plane wave. It is also assumed that the diameter of the incident light (D) is much greater than the thickness of the sample (D >> L). These assumptions simplify this problem to a one-dimensional case in the z direction. In addition, as the SHG intensity is proportional to I1(z). The generated SHG beam z) partially propagates along the z axis, and the SHG intensity passing through the sample surface at z = L is Ibeam2,, while the other part  diffuses to the whole sample via the scattering effect of dry powder before finally passing through all its surfaces (forward and backward). Therefore, in the general case, the total SHG intensity emitted by the sample will be given by:r represents the particle size and l1 and l2 are effective mean free path of fundamental and second-harmonic light, respectively.A SHG process diagram is depicted in Thus,f is the volume packing fraction, T1 represents the transmittance of fundamental light between medium and material, T2 represents the transmittance of second-harmonic light between medium and material, and I1,0 is intensity of fundamental light at z = 0. Moreover, g(r) is the function of particle size, second-order susceptibility coefficients ijd, and refractive indices; oε represents the vacuum dielectric constant; c is the light speed; and λ1 is the wavelength of the fundamental wave. PolFact is the “polarization factor” and nFact is a function of the principal refractive indices of the material for the wavelengths involved {, }. This depends on the sign of the birefringence and the type of PM. The values of PolFact and nFact are summarized in Itotal can be rewritten as:Here, l1 is usually small. Assuming that the sample is thick enough, that is, L, SHG strength is approximately independent of the sample thickness L:Since the sample is dry powder, the effective mean free path I2,total can be obtained:Substituting Equations (5) and (8) into Equation (7), analytical expressions for Equations (1)–(9) were proposed by Aramburu et al. in 2013 . On thisα is the absorption coefficient [R is reflection coefficient, andfficient ,61:(11)αSubstituting Equations (11) and (12) into Equation (10), the transmission expression can be given by:I2,total then becomes dependent on Eg, n, deff, and r of the sample:g), refractive index (n), effective NLO coefficient (deff), and particle size (r) of the material. Generally, in the process of SHG measurement, a standard sieve was used to divide the samples and the reference into the same particle size range. Notably, SHG intensity is only a function of deff when SHG measurements were performed under the same experimental conditions  and the refractive index and band gap of the sample were similar to those of the reference material. This conclusion is consistent with Equation (15). In this case, a qualified reference material should satisfy the following two criteria: (1) it should have a band gap close to that of the sample to be measured, which can minimize the issue of SHG response attenuation caused by optical absorption; and (2) it should have a refractive index close to that of the sample to be measured, which can minimize SHG intensity reduction caused by light scattering effects.According to Equations (9) and (14), total SHG intensity mainly depended on the band gap , the transmittance of the compound to the fundamental frequency light and the second harmonic light decreases with the increase in absorption α. Finally, according to Equation (9), the total SHG intensity measured by the Kurtz–Perry method decreases with the decrease in T1 and T2. In particular, when the wavelength corresponding to the band gap of a compound is close to 1045 nm, the experimental SHG intensity will be much lower than the theoretical value. For example, the band gap of Ba2Ge2Te5 is 1.15 eV, and the measured SHG intensity is about 0.45 times that of AGS while the theoretical NLO coefficient is about 16 times that of AGS. Secondly, the effect of refractive index on SHG intensity is also analyzed. On the one hand, according to Equation (13), both the numerator and the denominator of T decrease as the refractive index n increases, but the rate of decrease in the numerator is greater than that in the denominator. Thus, T decreases as n increases. On the other hand, the increased refractive index of the compound leads to an enhanced scattering effect, which reduces the SHG intensity that can be collected. Based on the above discussion and analysis, SHG intensity measured by the Kurtz–Perry method is significantly affected by the band gap and refractive index. The crystallographic information and linear optical properties of LBO, AGQ , ZGP, and BGQ  are listed in I2,beam decreases. Secondly, the larger refractive index of AGSe leads to the SHG wave being diffused throughout the sample via a scattering effect, and the contribution of I2,scatt is also reduced. Therefore, the measured SHG signal of AGSe is weaker than that of AGS.Herein, taking biaxial crystals satisfying type-I phase matching as an example  with AGS as the reference is 19.24 pm/V, while the coefficient obtained with AGSe as the reference is 50.75 pm/V. Obviously, the result obtained by the former is closer to the actual value. The reason for this phenomenon is that the band gap and refractive index of AGS are closer to the band gap and refractive index of BGSe than of AGSe . We beliThe powder second-harmonic generation (SHG) configuration is detailed in For this quantitative work, AGQ , BGQ , ZGP, and LBO powder samples were graded using a standard sieve with a particle size range of 20–50 μm. These samples were then clamped between two glass microscope slides (a 0.5 mm thick rubber gasket was added between the glass slides to ensure consistent sample thicknesses) and secured with tape in a 1 mm thick aluminum holder.eff(S)d of the sample is calculated by the following formula [S(2ω)I and R(2ω)I represent the SHG intensities of the sample to be measured and the reference material, respectively. Additionally, eff(R)d is the effective NLO coefficient of the reference.All NLO measurements were performed at room temperature. The measurement device is shown in  formula :(15)deffThe Kurtz–Perry method saves time and energy in material preliminary screening, but it also has some limitations. Therefore, optimizing the Kurtz–Perry theory for subsequent material evaluation is of great significance. Herein, on the basis of introducing the light scattering effect into the Kurtz–Perry theory, the theoretical expressions of band gap and refractive index on SHG intensity are derived. Subsequently, two factors affecting SHG intensity were deduced through theoretical analysis: band gap and refractive index. By comparison, the qualified reference should meet the following two standards: (1) it should possess a band gap close to that of the sample to be measured, which can minimize SHG response attenuation caused by light absorption; and (2) it should possess a refractive index close to that of the sample to be measured, which can minimize the influence of light scattering effects. This work may give rise to new inspiration of SHG evaluation in the future.


While the zwitterionic bilayers remain inert to lower pH and increased calcium concentrations, anionic membranes are responsive. Specifically, both bilayers enriched in phosphatidylserine (PS) and phosphatidylglycerol (PG) become dehydrated and rigidified at pH 4.0 compared to at pH 7.0. However, their reaction to the gradual Ca2+ increase in the acidic environment differs. While the PG bilayers exhibit strong rehydration and mild loosening of the carbonyl region, restoring membrane properties to those observed at pH 7.0, the PS bilayers remain dehydrated with minor bilayer stiffening. Molecular dynamics (MD) simulations support the strong binding of H3O+ to both PS and PG. Compared to PS, PG exhibits a weaker binding of Ca2+ also at a low pH.Biomembranes, important building blocks of living organisms, are often exposed to large local fluctuations of pH and ionic strength. To capture changes in the membrane organization under such harsh conditions, we investigated the mobility and hydration of zwitterionic and anionic lipid bilayers upon elevated H Helicobacter pylori survive in the highly acidic environment inside the stomach. Understanding all the aspects of its resistivity to low pH levels is of high interest as it causes serious gastric problems, threatening half of the world population -1-propanone (Prodan) were provided by Molecular Probes . Calcium chloride (CaCl2), sodium hydroxide (NaOH), 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES), hydrochloric acid (HCl), acetic acid (CH3COOH), and sodium acetate (CH3COONa) were acquired from Sigma-Aldrich. Liposome preparation: Liposomes were prepared by adding appropriate volumes of lipids (POPC (100 mol%), POPC:PS (60:40 mol%), POPC:PG (60:40 mol%), POPC:PE (60:40 mol%), and Laurdan (1 mol%) in test tubes and drying them under nitrogen and then keeping them in vacuum for 2 h. Lipid films were rehydrated in de-ionized H2O (Milipore USA) containing either 10 mM HEPES buffer (pH 7) or 20 mM acetate buffer (pH 4). Large-unilamellar vesicles (LUVs) were then prepared via extrusion through 200 nm filters . The final lipid concentration was kept at 1 mM with fluorescence probe concentration of 1:100 (mol/mol) with respect to the lipids. DLS/Zeta potential measurements: Dynamic light scattering technique was used to analyze the size of the liposomes prepared. Lipid samples were transferred to “dip” cell (UV grade poly (methyl methacrylate) cuvettes)  to acquire zeta potential measurements. Samples of 0.2 mM lipid concentration were first equilibrated at 298 K for 3 min before each measurement. Zetasizer Nano ZS , consisting of a He–Ne laser (532nm) and an avalanche photodiode detector (APD), was used for light scattering experiments and the signal was collected at an angle of 173°. Size distributions and values of zeta potential were generated using Zetasizer 6.2 software . Steady-state fluorescence spectroscopy: Steady-state spectra were acquired using an Edinburgh FS5 Spectrofluorometer with Xenon-arc lamp. Samples were transferred to 1.4 mL quartz cuvettes (Hellma), which were incubated for 5 min at 298 K. Temperature was maintained via water circulation bath. Excitation and emission spectra were recorded with the emission wavelengths of 440 and 490 nm, and excitation wavelength of 373 nm, respectively. Generalized polarization was obtained according to Parasassi et al. [i et al. :(1)GP=IeTime-dependent fluorescence shift (TDFS) method: Time-correlated single-photon counting (TCSPC) data were acquired using 375 nm laser  and IBH 5000U fluorescence spectrometer with cooled Hamamatsu R3809U-50 microchannel plate photomultiplier . Decays were collected in the range of the emission wavelength from 400 nm to 540 nm with an increment of 10 nm. An emission cut-off filter (cutoff: > 399 nm) was inserted into the detection arm of the set-up. An iterative re-convolution procedure was used to fit the measured multi-exponential decays using IBH-DAS6 software. The spectral reconstruction combining steady-state and TCSPC data generated time-resolved emission spectra (TRES) which were fitted by a log-normal function [ν(t) was used to calculate relaxation time rτ and overall dynamic Stokes shift Δν [ν(0) was estimated by means of the procedure described in [ν(∞) was obtained by extrapolation of the ν(t) dependence for t → ∞. function . The gaiMolecular dynamics: MD simulations were performed using the CHARMM36 [3O+ ions from a Kirkwood–Buff force field, optimized for SPC/E [3O+ assumes preference for the Eigen cation and the absence of covalently bound protons. The systems we simulated contained a 0.15 M KCl concentration. In addition, we added neutralizing K+ counterions, to compensate lipid charge. We  exchanged these counterions either with H3O+, Ca2+, or an equal mixture of the two, where equality was set by concentration, i.e., 26 H3O+ ions, 26 Ca2+ or, for the mixed system 17 Ca2+ and 18 H3O+. In total, six anionic lipid systems  and a POPC system were prepared. Our simulations included the NBFIX [CHARMM36  force fiCHARMM36 . We usedCHARMM36 . TemperaCHARMM36 . The timCHARMM36  with a cCHARMM36 . Then, tCHARMM36 , followeor SPC/E  and provor SPC/E . ModelinDynamic light scattering (DLS) and zeta potential measurements: DLS data are summarized in 2+ concentrations. Nevertheless, a larger scatter in the curves detected for DOPC:PS suggests the higher polydispersity of these liposomes compared to the other lipid compositions. Zeta potential profiles of different lipid compositions and their dependence on pH and Ca2+ concentrations are shown in 2+ cations is accompanied by similar effects for all the investigated lipid systems. The gradual increase in the zeta potential takes the place of up to 200 mM concentrations of Ca2+. At this threshold, due to overcharging [2+ concentrations [2+ cations is rather challenging [charging , all thecharging . Within charging . In additrations . In the trations ,54. Howellenging .Generalized polarization (GP) and time-dependent fluorescence shift (TDFS) in POPC, POPC:PE, POPC:PG, and POPC:PS bilayers. In general, an important prerequisite for the quantitative application of fluorescence techniques in biomembrane research is the knowledge of the depth of the fluorescence probe  inside the bilayer. Inevitably, the decrease in pH can result in the protonation of the dimethylamino moiety of Laurdan, which could potentially alter its positioning along the bilayer normal, causing the data misinterpretation. To rule out this potential artifact, we monitored the effect of pH on the emission characteristics of Prodan—a water-soluble analogue of Laurdan containing an identical fluorophore. As is evident from GP) [GP data obtained for the investigated lipid compositions are shown in 2+ and H3O+ concentrations   is utilitrations A. POPE-cadgroups . The GP p region B. MoreovGP measurements were also used for the assessment of the non-specific effects caused by the interaction of the counterions with the lipid headgroups [3O+ and Ca2+ cations, we monitored the GP dependence in the buffered systems  as well as the solutions containing only Cl- counterions  and overall dynamic Stokes shift (Δν) as a measure of mobility and extent of hydration within the carbonyl region, respectively. In spite of the broad use of the ed above ,60,61, ied above . Therefo2+ contents  and diminishes at 200 mM Ca2+ content. Factually, for these limiting Ca2+ concentrations, the proton impact on the bilayer organization becomes minimized as the Δν and rτ dependencies obtained for the investigated pH levels come closer to each other. The reduction in pH to 4.0 triggers substantial changes in the headgroup organization both for POPC:PG and POPC:PS. Please note that the latter liposomes undergo protonation of the serine carboxylate, causing partial loss of their anionic character as proven by the zeta potential measurements. In spite of this fact, the elevated proton concentration modifies the headgroups of POPC:PG and POPC:PS in a similar manner, dramatically reducing the level of hydration as well as mobility within the carbonyl region. At the elevated Ca2+ cations to POPC:PS liposomes at pH 4.0 shows different modes of action compared to POPC:PG. Particularly, the protonation of the PS headgroup at pH 4.0 appears to shield the effect of Ca2+ cations observed for the POPC:PG, since the relaxation time rτ increases with elevated Ca2+. In parallel, the overall Stokes shift Δν shows only a slight up-rise at the medium calcium concentrations followed by the subtle drop at the highest Ca2+ content. However, the observed changes are close to the TDFS detection limit and cannot compete with those observed for POPC:PG liposomes. The gradual addition of CaMD simulations: Simulations were conducted using H3O+ ions in SPC/E water. This means that Zundel ions and the covalent binding of protons to lipids are not part of the model. The use of the SPC/E water model is motivated by the parametrization of the H3O+ forcefield for this potential as well as the bad performance of the TIP3P model in the description of membrane surface tension [2, which is at the lower limit of the experimental values [2+ and H3O+, so that we accept these limitations of the simulation accuracy. Furthermore, we do not know the chemical potential of either the ions or water, so we cannot make a direct comparison to the experimental conditions. This limitation is common in MD simulations, but it nevertheless should be pointed out from time to time. In order to rigorously compare to an experimental concentration, it would be necessary to run a grand-canonical simulation, allowing for the exchange of ions and water with an external bath of defined concentration. Its chemical potential would then have to correspond to the experimental calcium concentration, as the simulation lipid concentration (appr. 0.4 M) is high compared to the experimental one.  tension . We simul values . In gene2+ and H3O+ on the anionic membranes, we find that both ions bind strongly to the anionic lipids. In 2+ and H3O+ are present. In addition, we show MD snapshots. It is evident that both ions bind more strongly to the headgroups than K+ and Cl- ions, as is expected. We find H3O+ to bind at a deeper level than the Ca2+ ions. Both ions are close to the position of the phosphate group, but Ca2+ appears to bind closer to the interface. It is clear that the binding patterns of both ions will be complex. In our MD snapshot shown in 2+ to be particularly well bound to the PS carboxyls, whereas the H3O+ ion is mainly coordinated via hydrogen bonds to the phosphate group. For PG, both ions seem to coordinate mainly to the phosphates. The strong preferential binding of Ca2+ to the carboxyls, in the case of PS, may be due to the used NBFIX correction, which is state-of-the-art for CHARMM. Recently improved force fields using ECC corrections have been proposed by the Jungwirth group [3O+ potential has not been released yet.Comparing the effects of Cath group . A compa2+ and H3O+ are more strongly bound to POPC:PS than to POPC:PG. The evidence is shown in the peak heights in 2+ binding is weak enough for regular dissociation on the simulation timescale. It is worth noting that, in a comparable simulation of pure POPC, with a different water model the binding of Ca2+ to PC was very weak [3O+ peak is enhanced by the presence of Ca2+  are slightly different. They are shown in 3O+. When comparing POPC:PS to POPC:PG, we find that both Caery weak . FurtherCa2+ see C and thePlease note that salt and lipid concentrations in MD simulations are usually very different from those of model experiments, e.g., the bulk concentrations in our simulation of PS are very low , but in the endoplasmic reticulum it can already exceed 500 μM and locally the calcium concentration can be increased to millimolar  . In thisnd yeast . For thend yeast  and perind yeast , and PS nd yeast , which i3O+ or to Ca2+ presence. In contrast, the anionic bilayers with the compositions POPC:PS and POPC:PG appeared to be highly responsive to both H3O+ and Ca2+, each of them in a different manner. At a low pH and in the absence of Ca2+, both bilayers become dehydrated and rigidified. Upon the Ca2+ addition at pH 4.0, the POPC:PG bilayers restore their hydration and fluidity, almost reaching the level observed for neutral pH. In contrast, in POPC:PS bilayers, the Ca2+ presence at acidic pH is barely detectable and only a mild stiffening of the membrane is noticed. We speculate that the protonation of the PS serine provoked by lower pH shields the effects, which are commonly observed upon Ca2+–membrane interaction [2+ cannot substitute the strongly interacting H3O+ ions. In contrast, simulations suggest that the binding of Ca2+ to PG is weaker than PS. In the experiments, at pH 4.0, both the bilayer hydration and mobility of DOPC:PS are affected by the gradual increase in Ca2+, to a lesser extent compared to the DOPC:PG membrane. We believe that these findings can bring a deeper understanding of the biophysical behavior of the lysosomal, vacuolar, and bacterial membranes and shed a light on the fate of drug nanocarriers under diverse conditions occurring in living organisms [We mapped the mobility and hydration within the carbonyl region of lipid bilayers with different headgroup compositions at elevated calcium and hydronium cation concentrations. TDFS data showed that the carbonyl region of the zwitterionic bilayers composed of POPC or POPC:PE was insensitive to either Heraction . MD simurganisms .


Not surprisingly, disturbances in Ca2+ homeostasis have been linked to neurodegenerative disorders, such as Alzheimer’s and Parkinson’s diseases. However, aberrations in Ca2+ homeostasis have also been implicated in neuropsychiatric disorders with a strong neurodevelopmental component including autism spectrum disorder (ASD) attention-deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). While plasma membrane Ca2+ channels and synaptic Ca2+-binding proteins have been extensively studied, increasing evidence suggests a prominent role for intracellular Ca2+ stores, such as the endoplasmic reticulum (ER), in aberrant neurodevelopment. In the context of the current mini-review, we discuss recent findings implicating critical intracellular Ca2+-handling regulators such as the sarco-ER Ca2+ ATPase 2 (SERCA2), ryanodine receptors (RyRs), inositol triphosphate receptors (IP3Rs), and parvalbumin (PVALB), in the emergence of ASD, SCZ, and ADHD.Calcium (Ca Of the elopment . Readersisorders . Interesisorders , 2020. I2+-releasing channels expressed on the neuronal ER membrane; upon opening, the RyRs allow for the flux of Ca2+ ions from the ER stores into the cytosol  genes have both been associated with impaired Ca2+ signaling. Specifically, preclinical evidence suggests that the human T4826I-RYR1 gain-of-function mutation and the human CGG-repeat expansion in the FMR1 gene , are both associated with elevated intracellular Ca2+ signaling; indeed, the T4826I-RYR1 gain-of-function mutation has been shown to result in increased intracellular Ca2+ concentrations in muscle cells  mice  mice . InteresDM) mice . Based o results .Ryr1 and Fmr1 and polychlorinated-biphenyls (PCBs) exposure in ASD-like behaviors  positive interneurons of the brain that exhibit rapid burst-firing activity and are heavily dependent on intracellular Ca2+-handling , the molecular layer interneurons (MLI) of the cerebellum, the prefrontal cortex, and the striatum  is a Cahandling . While dttention . Intereshenotype . Recentlpression . Interesstriatum . Furtherstriatum . Taken t rely on . Ultimat3R Ca+2 signaling pathways comprise critical components of the intracellular Ca+2 handling machinery with potential implications in ASD  showed that ATP-evoked GPCR-mediated Ca2+ release from the IP3Rs was diminished in ASD fibroblasts -mediated IPs in ASD . For insehaviors . Interesroblasts . In a fo2+ signaling processes observed in the maternal-ubiquitin protein ligase E3A (Ube3a) deficient mouse model for AS  is a developmentally regulated ER resident protein and negative regulator of SERCA that is expressed in the brain’s PVALB + GABAergic neurons; NNAT has also been implicated in abnormal neurodevelopment, including ASD and Angelman Syndrome (AS) . The miRl for AS . UBE3A pl for AS . Recentling NNAT . Taken t2+ homeostasis, namely: RYR3 [discussed in the Section “2.1. Ryanodine receptors (RyRs) and the fragile X messenger ribonucleoprotein 1 (FMR1)”], ubiquitin protein ligase E3 (UBR3), and filamin A (FLNA) (2+ channel (Cav1.2) via the ubiquitin-proteasome protein degradation pathway and has been identified as a modulator of Ca2+ -induced Ca2+ release (CIRC)  . UBR3 ine (CIRC) . FLNA isosophila . Overall2+ signaling is also prevalent in astrocytes; while astrocytic dysfunction has been implicated in the pathophysiology of ASD, the precise mechanisms by which astrocytes contribute to disease progression and symptomatology remain elusive . Given the exaggerated Ca2+ response observed in ASD astrocytes, it was predicted that inhibition of IP3Rs would possibly restore Ca2+ signaling and function. Intriguingly, IP3R-knockdown in ASD astrocytes rescued the exaggerated Ca2+ response, hippocampal neuron network firing, and deficits in fear memory observed in chimeric mice  which comprise physical connections formed between the ER IP3Rs and mitochondrial voltage-dependent anion channels (VDAC) that are involved in the transfer of Ca2+ and molecular stress signals between these two organelles  to investigate how developmental hypofunction of Serca2 may affect SCZ-relevant behavioral and neurobiological processes (2+ uptake (Serca2 hypofunction induces a hyperdopaminergic state in the nucleus accumbens (NAC)  , echoingns (NAC) . Taken tde novo variants of RYR2, which the authors highlight as a strong candidate gene given the role of RyRs in neurodevelopmental processes  model of ADHD has been shown to exhibit impaired brain plasma membrane Ca2+ uptake (Gnb5) elicits a pronounced ADHD-like hyperactive phenotype in mice  associated with impaired termination of DA2 receptor signaling was reported in a Saudi family presenting speech impairments and a variable ADHD diagnosis, providing initial clinical evidence for the putative role of GNB5 in the neurobiology of ADHD (2+ entry (SOCE) , an ER Ca2+ sensor, forms a complex with the plasma membrane calcium release-activated calcium channel protein 1 (ORAI1) to initiate extracellular Ca2+ entry  . Upon de2+ entry . Kang et2+ regulators  in the neurobiology of brain disorders with a strong neurodevelopmental component (2+ signaling mechanisms, whereas sporadic cases of SCZ, ASD, and ADHD may arise from polygenic variations that ultimately converge to the disruption of intracellular Ca2+ homeostasis and concomitant impairment of neuronal function. Further preclinical and clinical investigation is considered imperative to confirm and/or expand upon these intriguing discoveries in order to gain deep insights into the cellular and molecular Ca2+-dependent neurodevelopmental processes that are compromised in these debilitating brain diseases.In the context of this mini-review, we have highlighted recent advances supporting the implication of prominent ER and cytosolic Caomponent . DiseaseBK conducted the primary literature search and wrote first draft of the manuscript. KK, JT, CM, and HO wrote sections of the manuscript. PP formulated the concept and supervised the writing of the manuscript. All authors contributed to manuscript editing, revision, read, and approved the submitted version.


Its three-dimensional orientation and nanoscale morphology are important for growth optimization. In this paper, we introduce an imaging technique based on circular dichroism second-harmonic generation (CD-SHG) to characterize the 3D distribution of KTP nanocrystal. A rigorous theoretical model of CD-SHG imaging for nano-KTP through stratified media is demonstrated. Circular dichroism analysis is used to probe the orientation of 3-axis with respect to the optical observation axis. The research results show that the azimuthal angle of the peak value (SHG) or valley value (CD-SHG) is strongly related to the excitation polarization when the KTP sample is excited by different circular polarizations. Importantly, the refractive index mismatches and the imaging depth also affect the azimuthal angle. Thus, the proposed framework enables a more precise quantitative analysis of the CD-SHG signal of KTP.Potassium titanyl phosphate (KTiOPO SHG-based techniques have been applied in the investigation of semi-conductor nanowires with different composition and nanoscale morphology detection of nano-objects . Importan fields . Moreoven fields . HoweverIt is worth noting that in polarization-resolved SHG microscopy for crystal material, the specimen is often observed with a high NA objective with immersion medium and a cover glass. Moreover, they usually have different refractive indices. For example, the refractive index of KTP is 1.738  , which iHere, we present a rigorous theoretical framework of CD-SHG microscopy through stratified media for KTP crystal. The SHG intensity patterns for left-handed and right-handed circular polarized excitations and the corresponding CD-SHG signal obtained in a mismatch free medium and in a mismatched stratified media will be compared from several aspects. The quantitative analysis of azimuthal angle of SHG signal and the SHG response to a specific point object as a function of the effective NA in different depths will be demonstrated. In addition, circular-polarization-excited SHG imaging in index-mismatched media in the case of a vertical interface between water and a KTP material are investigated based on FDTD methods. As a complementary polarization-resolved scheme, CD-SHG imaging not only provides intrinsic 3D imaging capabilities with sub-micrometer spatial resolution, but also paves the way for determining the local 3D orientation of KTP molecules information with a new structural contrast mechanism. We also expect that the study can contribute towards new insights into optimization of CD-SHG microscopy instrumentation.z = −h1, and the second at z = −h2. The wave numbers of the light beam in the immersion medium, cover glass and specimen are k1, k2, and k3, respectively. k1 = 2πn1/λ0, k2 = 2πn2/λ0, and k3 = 2πn3/λ0. n1, n2, and n3 are the refractive index of the immersion medium, cover glass, and specimen respectively.N-layer medium are derived. Under the idiomatic polar coordinate system notation, the Cartesian components of the electric field in the focal region can be expressed as:rP, θP, ϕP) are the spherical polar coordinates of an observation point P near the focal region, respectively. α1 is the convergence semi-angle of the illumination, and is given as α1 = arcsin (NA/n1). l0 (θ1) is the amplitude function in terms of θ1 and Jn(x) denotes a Bessel function of the first kind, of order n. p- and s-polarized light traversing N−1 media respectively and calculated as in ψi denotes the initial aberration function. Based on the Richards–Wolf vectorial diffraction integral , the genAs the focal electric field distribution is determined, the interaction with the material can be calculated. SHG intensity has a quadratic relationship with the optical field intensity of the excitation beam at the focus region, which is also dependent on the nonlinear susceptibility tensor of the sample. When the frequency of the laser light source is far away from the resonant frequency of the specimen, the number of non-zero elements in this third-order tensor with 27 separate elements reduces according to Kleinmann’s symmetry . SHG polE1 traverses back the stratified medium  denotes the Cartesian components of the complex conjugate of P. The transmission coefficients Ts’ and Tp’ for the stratified medium can be calculated as in N to medium 1.The SHG polarization emits corresponding radiation, and the harmonic field d medium . The disd medium :E1x′=12E2 in the intermediate plane is given by , and the image space, respectively, expressed as kd0 = 2π/λSHG, kd1 = 2πn1/λSHG, and kd = 2πnd/λSHG. λSHG denotes the wavelength of SHG. nd is the refractive index of the image space. The aberration function in the detection path ψdet can be expressed byHence, the expression for the SHG field components at the detector plane can be obtained by using the integral formula of Richards and Wolf , as:EdxAs a result, the detected SHG intensity excited by left-handed and right-handed circular polarized beams through stratified media can be obtained according to:In the end, CD-SHG is measured as the normalized difference between SHG signals rization :CD−SHG=d (in pm/V) of KTP has been measured  and mismatched stratified media, excited by left-handed and right-handed circular polarized beams at different imaging depths, are shown in λ = 1,064 nm and an oil immersion (n1 = 1.518) objective of NA = 1.2 is considered. The nominal magnification of the imaging system M is set to 100. For the mismatched stratified media, the KTP specimen (n3 = 1.738) is mounted below a 170-µm cover glass (n2 = 1.525). The imaging depth (h2) is set to 20, 40, 60, and 80 µm, respectively. It is easy to observe a variation for the SHG intensity pattern when the KTP sample is excited by different circular polarizations. The azimuthal angle of the peak value (SHG) or valley value (CD-SHG) were calculated, as listed in z-axis and has no side lobes. The location of the peak intensity is at the nominal focus. In contrast, for the mismatched layered media, there is an aberrational focus shift. As the imaging depth increases, the displacement increases and the stretching of the intensity distribution in the z-direction becomes more pronounced. In this context, the three-dimensional orientation of KTP can be probed via the sign, azimuthal angle, and CD-SHG amplitude distribution. At the same time, the nanoscale morphology can be revealed by the scanned CD-SHG images.The SHG intensity patterns for a refractive index perfectly matched, aberration-free medium , which corresponds to the SHG signal peak location of aberration-free medium excited by left-handed circular polarized beams. The distribution along each vertical section shows the axial distribution for a given NA. Each distribution is normalized to the respective maximum intensity. The results for focusing into a perfectly matched, aberration-free medium are shown in The effects of varying effective NA when focusing to a certain depth in the specimens is essential for the optimization of the experimental polarization-resolved SHG configuration. The variation of effective NA is controlled by changing the pupil size with the iris. The other configuration parameters of the polarization-resolved SHG imaging system are identical to the system described above. 3 × 15 μm3 × 8 μm3 discretized over 50-nm steps. The simulation time resolution is set to 160 fs. The intensity distribution is calculated as the beam was focused 5 µm below the sample surface. FDTD simulations were performed with Lumerical version 2020a in the Microsoft Windows 10 operating system. The calculation was implemented on a PC equipped with Intel Core i7-11800H CPU and one NVIDIA GeForce RTX 3050Ti Laptop graphical processing unit (GPU) with a typical computing mesh accuracy of 3. As shown in For a vertical interface between materials with refractive index mismatches, it has been found that commonly used diffraction-integral-based simulation strategies fail to generate accurate SHG distribution. In contrast, the FDTD family of methods calculate the electric fields at every point of a 3D grid in successive times by solving discretized Maxwell equations for specified materials. The implementation details and the validity of FDTD strategies in the context of nonlinear microscopy have been demonstrated . Figure Next, the capability of FDTD methods to model circular-polarization-excited SHG imaging in index-mismatched media in the case of a vertical interface between water and a KTP material are investigated. For the KTP material, a non-zero diagonal second-order susceptibility was considered. We speculate that index mismatch of the vertical interface results in significant profile distortions. In summary, we have demonstrated a previously unidentified rigorous model to demonstrate circular dichroism SHG microscopy through stratified media for KTP crystal. In our proposed model, the refractive index mismatches and the imaging depth are taken into account for quantitative analysis of the CD-SHG signal. It has been demonstrated that the azimuthal angle of the peak value (SHG) or valley value (CD-SHG) is strongly related to the excitation polarization when the KTP sample is excited by different circular polarizations. Importantly, for the same excitation, the refractive index mismatches and the imaging depth also affect the azimuthal angle. Besides, the numerical framework based on FDTD can be an applicable simulation strategy to investigate CD-SHG microscopy with sample refractive index heterogeneity. It is expected that the proposed model can contribute towards new insights into nanoscale morphology of KTP and the experimental configuration optimization of CD-SHG microscopy.


RUNX1-RUNX1T1 AML. Thyrotropin-releasing hormone (TRH), as biomarkers of CD34+CD117bri myeloblasts, were found to be prognostic in RUNX1-RUNX1T1 AML. However, the clinical and genetic features of TRH in AML patients are poorly understood. Here, with data from TCGA AML, TRH was found to be downregulated in patients older than 60 years old, with DNMT3A and NPM1 mutations, while overexpressed in patients with KIT mutations. This was further validated in three other cohorts of primary AML including Beat AML (n = 223), GSE6891 (n = 461), and GSE17855 (n = 237). Furthermore, we demonstrated that the expression of TRH in AML could be used to improve the ELN 2017 risk stratification system. In conclusion, our preliminary analysis revealed that TRH, a novel biomarker for AML patients, could be used to evaluate the survival of AML.Acute myeloid leukemia (AML) is a biologically and genetically heterogeneous hematological malignance with an unsatisfactory risk stratification system. Recently, through the novel single-cell RNA sequencing technology, we revealed heterogeneous leukemia myeloblasts in  Acute myeloid leukemia (AML) is a genetically and biologically heterogeneous hematological malignance with impaired hematopoiesis and bone marrow failure . To induRUNX1 and TP53 for AML stratification, which underlined the importance of genetic mutations in disease prognosis [Clinical risk stratification for AML is complex due to patient-associated factors and disease-related factors . Especiarognosis . Gene exrognosis .+ myeloblasts, namely, CD34+CD117dim and CD34+CD117bri, in t  AML (RUNX1-RUNX1T1 AML) [TRH), one of the biomarkers for CD34+CD117bri myeloblasts, was observed to be highly expressed in AML patients, especially in those with RUNX1-RUNX1T1 AML [TRH, encoding a member of the thyrotropin-releasing hormone family, is involved in the hypothalamus–pituitary–thyroid (HPT) axis which exhibits feedback of thyroid hormone, thereby regulating metabolic and immunological homeostasis [TRH expression was an independent prognostic factor for overall survival (OS) in t  AML after adjustment for clinical and genetic parameters [TRH expression and clinical characteristics, genetic features, and immunological profiles in AML is poorly understood. In this work, we investigated the distribution of TRH expression in cancers, especially in different subtypes of AML. Based on our previous findings in t  AML, we further explored the clinical, genetic, immunological, and metabolic relevance, as well as molecular regulation correlated with TRH expression in AML patients. Through investigating the relationships between TRH expression and clinical prognosis, and genetic alterations, new ideas for the risk stratification and treatment of AML may be obtained.Recently, we reported the heterogeneous populations among the CD34ri, in t ;21 AML ) [www.vizome.org/aml (accessed on 15 January 2022)) [https://www.ncbi.nlm.nih.gov/geo/ (accessed on 13 July 2022)) [https://www.ncbi.nlm.nih.gov/geo/ (accessed on 13 July 2022)) [RUNX1-RUNX1T1 AML patients were obtained from our previous studies [The transcriptome profiles of AML data, along with the detailed clinical information, were downloaded from public databases, including the Cancer Genome Atlas (TCGA) (e 2021)) , Beat AMy 2022)) , GSE6891y 2022)) ,18,19. TRUNX1-RUNX1T1 transcript in t  AML as previously described [Differentiation expression analysis was performed by using DESeq2 . The expipt in t ;21 AML aipt in t ;21 AML aescribed .p < 0.05 was viewed as significant and further analyzed. Correlation between TRH expression and immune cells inferred by CIBERSORT was determined by Spearman correlation.CIBERSORT was used to explore the proportion of immune cells in the bone marrow microenvironment as previously described . Specifihttp://gepia2.cancer-pku.cn/ (accessed on 2 July 2022) [TRH from TCGA and Genotype-Tissue Expression (GTEx) databases. BloodSpot (https://servers.binf.ku.dk/bloodspot/ (accessed on 15 September 2022)) [TRH expression with data from the collaborative Microarray Innovations in Leukemia (MILE) study [http://dbtoolkit.cistrome.org/ (accessed on 23 July 2022)) [http://cbioportal.org/ (accessed on 23 July 2022)) [TRH expression and methylation levels, respectively. The expression level of TRH and predicted chemothearpeutic response were downloaded from the Genomics of Drug Sensitivity in Cancer ) [The online platform Gene Expression Profiling Interactive Analysis   was usedr 2022))  was usedE) study . The Cisy 2022))  and cBioy 2022))  were usee 2022))  to analyP value. Statistical analyses were performed with R software ).The Kaplan–Meier method was used to estimate the probability of overall survival (OS). Log-rank tests were used to compare the TRH in pan-cancer is rarely reported. Here, GEPIA2 [TRH was actually low in most cancers and matched normal tissues , inv (16), and t  were higher than those in patients with acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), and myelodysplastic syndrome (MDS)  had a significantly differential expression of TRH compared with the normal ovaries (p < 0.05)  and overall survival (p = 0.23)  . With si tissues . In addi < 0.05) . Further = 0.23) . Thus, tTRH compared to healthy populations   . For theTRH expression, the RNA-seq data from RUNX1-RUNX1T1 AML patients (n = 62) [TRH-high (n = 31) and TRH-low (n = 31), based on the median level of TRH expression. Considering the role of the fusion RUNX1-RUNX1T1 in t  AML, we analyzed and compared the RUNX1-RUNX1T1 fusion between these groups . The Cistrome [TRH, which consisted of JARID2, FOXA1, SPI1, and ESR1 , ESR1  , nor RUNX1T1    were anae groups a. We fouCistrome  databaseand ESR1 b. Furthe= 0.038) c. Howeve = 0.12) c.TRH-high group had significant activation of the oxidative phosphorylation pathway, citrate cycle, TCA cycle pathway, and the alanine aspartate and glutamate metabolism pathway, thus demonstrating the activation of metabolism-relevant pathways  showed that the pathways . In addipathways . Furthernd U2AF2 e. For thpathways .TRH expression in AML patients. With data from the TCGA AML project (n = 145), we found that AML patients older than 60 years had a lower expression of TRH (p = 0.05)  or gender subgroups  a. There ubgroups .TRH expression with common driver mutations of AML. In the TCGA AML cohort, AML patients with KIT mutations and RUNX1 mutations had a significantly higher expression levels of TRH compared with the wild-type groups   compared with the corresponding wild-type groups .We then analyzed the correlation of ctively) . On the e groups c. HoweveL cohort . We alsopression d and fouTRH expression in other AML cohorts, we screened and obtained RNA-seq data of primary AML from Beat AML cohort (n = 223) [TRH in AML patients older than 60 years old, reaching a statistical significance (p = 0.027) (TRH (p = 0.012)  (DNMT3A mutations and NPM1 mutations had lower expression levels of TRH (p < 0.0001) (KIT mutation had a higher expression of TRH (p = 0.0004)  . We also= 0.027) a. AML pa= 0.012) a. The ge 0.0004) b. In add 0.0001) c. Moreov 0.0004) b. These mutation .n = 461) [n = 237) [NPM1 mutations had significantly lower expression of TRH (p < 0.001) in both GSE6891 and GSE17855 (FLT3-ITD mutations had significantly lower expression of TRH in GSE6891 (p < 0.001) (KIT mutation had a higher expression of TRH in GSE17855 (p < 0.001)  ,16 and Gn = 237) ,18,19. WGSE17855 d,e. In a< 0.001) d. AML pa< 0.001) e.TRH-low group, we then analyzed the immune infiltration in the bone marrow of RUNX1-RUNX1T1 AML patients using the CIBERSORT algorithm [TRH expression and monocytes  and eosinophils   (Considering the activation of immune-related pathways in the lgorithm . Correla = 0.04) a. In the T cells . Consist = 0.03) .TRH expression on drug resistance, data from the GDSC database [TRH-high group had a significantly lower IC50 for AML chemotherapeutics, including cytarabine (p = 0.014) and doxorubicin (p = 0.0018) (TRH-high group had a lower IC50 for ATRA (p = 0.015), which was used in acute promyelocytic leukemia patients  b, which patients b.TRH expression in different cytogenetic risk groups. In the TCGA AML cohort, we found that the favorable group of the ELN 2017 risk system had a significantly higher level of TRH expression than both the intermediate and adverse groups (TRH (p < 0.001) (TRH groups in the intermediate group (p = 0.0408) and adverse group (p = 0.284), respectively, in the TCGA AML cohort (TRH expression had prognostic significance (p < 0.001), WBC count , TRH expression , and ELN 2017 risk . The multivariate analysis showed that age , WBC count , TRH expression , and ELN 2017 risk  remained independent prognostic factors for OS. Collectively, these data indicate that the expression of TRH could be used to further stratify AML patients on the basis of the ELN 2017 risk system.The European Leukemia Net (ELN) risk stratification system for AML  is commoe groups a. In the< 0.001) b. KaplanL cohort c. Furtheificance . The resRUNX1-RUNX1T1 AML, we further extended the research of TRH expression in AML. We revealed the genetic, immunological, and clinical features correlated with TRH expression in the TCGA AML cohort, and further validated these results in three other cohorts. Furthermore, we showed that TRH expression could complement and refine the accuracy of the ELN 2017 risk stratification system for AML.In this work, based on what we discovered previously in TRH is known to be a component of the hypothalamic–pituitary–thyroid axis, and is involved in the regulation and release of thyroid-stimulating hormone. Recently, with single-cell RNA-seq, we revealed heterogeneous myeloblast populations and their relevant biomarkers in patients with RUNX1-RUNX1T1 AML [TRH, as one of the relevant biomarkers, was proved to be an independent prognostic risk factor in RUNX1-RUNX1T1 AML. In this study, we found that the top activated pathways in the TRH-high group of RUNX1-RUNX1T1 AML were the oxidative phosphorylation pathway, the citrate cycle, the TCA cycle pathway, and the alanine aspartate and glutamate metabolism pathway. This revealed the aberrant activation of metabolism signaling pathways in the TRH-high group. In addition, the expression of TRH in t  AML was not regulated by the RUNX1-RUNX1T1 fusion. This might be due to genetic or epigenetic changes leading to the regulation of TRH expression. In fact, through the query of the RNA-seq data of pan cancer, TRH was barely expressed in a variety of cancers, which might be attributed to its methylation status [X1T1 AML ,9. TRH, n status ,31.TRH expression in a variety of hematological cancers including ALL, CLL, CML, and MDS. Unlike AML patients, those with these hematological diseases presented relatively lower expression levels of TRH, suggesting that TRH was a characteristic biomarker for AML. We further explored the underlying correlation of TRH expression with genetic changes in AML. We observed lower expression levels of TRH when AML patients harbored DNMT3A or NPM1 mutations in four independent cohorts. However, when AML patients carried KIT mutations, they presented higher TRH expression levels. This may be due to the fact that the KIT mutation frequently occurred in patients with RUNX1-RUNX1T1 AML. In addition, TRH was reported to be highly expressed in RUNX1-RUNX1T1 AML patients by other studies [With data from the MILE study ,25, we a studies ,33.TRH, which could be used to further stratify AML patients. We also found that patients with higher expression of TRH in AML appeared to be more sensitive to chemotherapy. Future studies are still needed to explore the drugs that were more effective in the TRH-low group.Early identification of high-risk AML and administration of intensive chemotherapy and transplantation could greatly reduce the relapse rate. Thus, the European Leukemia Net has proposed a risk stratification system that incorporates cytogenetic mutational status and has been widely used clinically . RecentlTRH, in AML patients. Our preliminary analysis suggests that TRH could refine the ELN 2017 risk stratification system.In conclusion, we explored the clinical and genetic features of a novel biomarker,


Similarly, inflammation entails complex processes, where [Ca2+]i also play crucial roles. Deregulation of this second messenger increases cell damage and promotes fibrosis, reduces renal blood flow, and impairs the glomerular filtration barrier. In vertebrates, [Ca2+]i signaling depends, in part, on the activity of two families of large-pore channels: hemichannels and pannexons. Interestingly, the opening of these channels depends on [Ca2+]i signaling. In this review, we propose that the opening of channels formed by connexins and/or pannexins mediated by AngII induces the ATP release to the extracellular media, with the subsequent activation of purinergic receptors. This process could elicit Ca2+ overload and constitute a feed-forward mechanism, leading to kidney damage.Hypertension is one of the most common risk factors for developing chronic cardiovascular diseases, including hypertensive nephropathy. Within the glomerulus, hypertension causes damage and activation of mesangial cells (MCs), eliciting the production of large amounts of vasoactive and proinflammatory agents. Accordingly, the activation of AT1 receptors by the vasoactive molecule angiotensin II (AngII) contributes to the pathogenesis of renal damage, which is mediated mostly by the dysfunction of intracellular Ca The kidney is commonly described as an excretory organ and is essential to maintaining systemic homeostasis ,2. KidneCKD embodies different etiologies, including diabetic nephropathy, hypertensive nephrosclerosis, and glomerulonephritis. However, regardless of the causes, some morphological changes are common, including tubular necrosis and glomerular sclerosis ,10,11 F. The patBased on the renin localization, mainly in granular cells of the renal afferent arteriole, it is assumed that swelling or shrinking of the juxtaglomerular apparatus (JGA) is involved in the glomerular blood flow ascribed to the renin–angiotensin system (RAS). These cells make contact with the extraglomerular mesangium and macula densa, forming the JGA . The uniAngII regulates blood pressure, intravascular volume, and electrolyte balance by acting on the kidneys and adrenal glands . TreatmeThe renal corpuscle comprises the Bowman’s capsule and the glomerulus, both being fundamental structures for blood filtration. The Bowman’s capsule plays a vital role in the structural and functional stability of the glomerulus, allowing it to fulfill its filtering function successfully ,33. StruGap junctions (GJs) are aggregates of ten to thousands of individual intercellular channels that permit the cytoplasmic exchange between adjacent cells. They allow the diffusion of ions, small metabolites , and second messengers  between adjacent cells ,41,42. T2+ concentration ([Ca2+]i) [+ and Cl− through HCs may result in osmotic and ionic imbalances coupled to further cell swelling and plasma membrane breakdown [2+ [2+]i mediated by HCs could lead to Ca2+ overload and consequent induction of different proteases, phospholipases, and other hydrolytic enzymes, as well as oxidative stress and caspase activation i) , pH 57]2+ concen[Ca2+]i)  and S-ni[Ca2+]i) ), and pr[Ca2+]i) . Neverth[Ca2+]i) ,61,62. A[Ca2+]i) . Firstlyreakdown ,64,65. Sdown i to renin-secreting cells i increases [2+]i–induced Panx1 channel opening likely contributes to the progression of cell death. Critical in perpetuating this phenomenon could be the P2X receptor activation, as it leads to persistent Ca2+ entry and subsequent stimulation of intracellular toxic cascades i overload and the consequent production of free radicals, lipid peroxidation, and plasma membrane damage [2+]i raised the activity of Panx1 channels allowing the release of ATP and further activation of P2X7 and P2Y1 receptors i upon stimulation with TNF-α [7Rs [On the other hand, more recent evidence has proposed that Panx1 channels increase [Cath TNF-α , which cth TNF-α . Panx1 hth TNF-α ,156, andth TNF-α . Indeed,th TNF-α ,158. Rec2+ and IP3 receptor-dependent release of Ca2+ stored in the endoplasmic reticulum. This could occur in the companion of the Panx1 channels-dependent release of cytokines, all these processes being simultaneous, as previously demonstrated in other cell types [It is known that high extracellular ATP levels contribute to the transformation of MCs and promote renal injury in AngII-dependent hypertension ,160 Fig. The latll types ,162 (Figll types ,164.For years, hypertensive kidney disease has been considered a disorder limited to afferent arterioles and glomeruli in which the mechanical stresses induced by hypertension, RAS stimulation, and activation of resident fibroblasts were thought to be crucial in underlying kidney damage . FindingDespite existing tools, such as connexin KO mice and connexin-blocking peptides, knowledge about connexin implications in renal physiology is still limited . Moreove


In this paper, the effect of interlaminar properties and the type of delamination defects on the residual compression properties of carbon fiber laminates were experimentally investigated. A new method, which employed magnetic force to guide the arrangement direction of stainless steel particles between layers of laminates, was adopted to improve the interlayer toughness. The digital image correlation, C-scan, and micro-CT were used to measure and identify the compression failure damages. Test results showed that the compressive strength of the intact carbon fiber laminates was 299.37 MPa, and the one of specimens containing the deeply buried delamination, the through-width delamination, and the surface delamination decreased by 55.98 MPa, 58.69 MPa, and 60.23 MPa, respectively. The compressive strength of the specimens containing the deeply buried delamination only decreased by 14.01 MPa when the mode I toughness increased by 81.88%, and the specimen containing the surface delamination only decreased by 30.86 MPa when the mode II fracture toughness increased by 87.72%. However, improving the fracture toughness could not strengthen the specimens containing the through-width delamination. Moreover, a qualitative dynamic damage relationship, which described the relationship between delamination expansion and compression damage vividly, was proposed. The reason the increase of the toughness could improve the residual compression performance of the laminates containing delamination was that the higher fracture toughness hindered the secondary expansion of the delamination during the compression process so that the delamination area could almost remain unchanged. Carbon fiber laminate is a new material with high specific strength and high specific modulus, and thus widely used in various fields ,2,3. DelWhy delamination damage is so fatal is attributed to the unique structure of laminated composite materials ,15. It iThe most common way to study the residual properties of laminates is the compression after the impact test ,19,20,21To study the influence of delamination alone on the residual compressive capacity of the laminates, therefore, some scholars artificially made the initial delamination during the molding of composite materials ,29,30,31The delamination of composite laminates is one of the factors limiting their practical application. Thoroughly understanding the mechanical behavior of delaminated composites is important for damage tolerance design of laminated composite structures. Currently, scholars have studied the effects of delamination location ,35 and dThe residual compressive properties of the specimens containing three different types of delamination defects are tested and compared, and a new interlayer toughening method is used to toughen the materials. Magnetic force is used to guide the cylindrical 410 stainless steel particles aligned along thickness direction to achieve the interlayer toughening. This toughening method is able to guide the orientation of the particles arranged between the layers from the outside of the laminate during the forming process. The particles uniformly arranged along the thickness direction can form a stronger bridging structure than randomly distributed particles, thus enhancing the fracture toughness of the material more effectively. By comparing the compressive properties of materials with and without a toughening treatment, the effect of interlayer toughening on the residual properties of materials with delamination is obtained. Furthermore, the mechanical behavior of different types of specimens under compression is studied and the mechanism of toughening is discussed. Based on the test results, a dynamic damage relationship suitable for describing the relationship between delamination propagation and compression failure is proposed. It is hoped that the reported results can provide a reference for the innovative design of interlaminar toughening of composites and methods to improve the material damage residual properties.6. The thickness of the specimen was 2.85 mm. Aluminum tabs were pasted at both ends of the specimens, schematically shown in A compression specimen was designed, as shown in The wet hand layup molding was adopted to fabricate the specimens. Although the molding method is a primitive method, it is suitable for artificially introducing delamination between layers and particles. To artificially introduce delamination defect, a piece of 0.04 mm thick poly tetra fluoroethylene (PTFE) film was placed in the designated location between ply-3 and ply-4 to prevent resin infiltration. Three types of embedded delamination were introduced, namely, the deeply buried delamination crack (DB), the surface delamination crack (SC), and the through-width delamination crack (TC), as shown in 2, which is different from the material intrinsic density. Three different densities of particles were prepared, namely, 0 g/m2 (particle-free), 30 g/m2, and 60 g/m2, respectively. For the convenience in presentation, symbols 0, 30, and 60 were used to distinguish the particle densities in different groups of specimens.The interlayer toughening method used is a new type of magnetically guided particle toughening method that uses a magnetic field to guide the distribution direction of the particles filled in the interlayer to enhance the particle toughening effect. To ensure that the particles could be magnetically guided, the 410 stainless steel particles were chosen as the filler. The shape of the particle is cylinder with a cross-sectional radius of 0.015 mm and a length between 0.10 and 0.20 mm. A steel particle with such a size is more conducive to the rotation of the particles between the layers, and can enter the pores of the fiber cloth to make the coupling between the fibers and the layers stronger. Before the composite material was laid, a certain mass of particles was weighed by an electronic scale with an accuracy of 0.1 mg. Particle density mentioned here and elsewhere in this article denotes the content of particles per unit area between layers and its unit is g/m2 and guided by a magnetic field was named as “30-SZ-SC”.To fill the particles into layer, a 100-mesh sieve was used to put the particles between the layers. In the preparation of the specimens for this experiment, the particles were only filled into the layer containing the delamination defect. One more step for manufacturing certain specimens, named as SZ group, is to apply a fixed direction magnetic field from the outside when the resin has good fluidity. The reason for this step is to effectively guide the cylindrical particles to be distributed vertically. For comparison, samples with the same particle density without magnetic field guidance were also prepared, named as SJ group. In order to distinguish different kinds of specimens more conveniently, the rule to name the specimens is “Density symbol”—“Processing method”—“Crack type”. For example, a specimen, containing an embedded surface crack, with a particle density of 30 g/mIn order to confirm that the magnetic guidance method can indeed change the distribution direction of particles, the article also scans the interior of the two materials with the micro-CT technology, as shown in In ASTM D7137 standard , the sizThe quasi-static compression test was completed by the MTS 810.25 tester and the digital image correlation (DIC). The specimen was installed to ensure that its long axis was parallel to the loading direction to prevent shear stresses, as shown in The UltraPAC ultrasonic C-scanner, shown in To monitor the global displacement changes in all directions during the compression process of the specimen, especially the distribution of out-of-plane displacement, the DIC test technology was employed to observe and measure the global compression process of the specimens. The measurement hardware and software , shown in To study the influence of toughening methods on the fracture toughness of materials, the interlaminar mode I and mode II fracture toughness of materials were also tested under different working conditions. As shown in the 2. Strains were measured by strain gauges. A pair of strain gauges was located on the same position of upper and lower surfaces of the specimen to monitor the possible bending deformation. By comparing the characteristics of stress–strain curves at different positions on the upper and lower sides, one can analyze the impact severity and mechanism of delamination defects on the mechanical properties of the laminated composite material.It is seen that the stress–strain curves of the upper and lower sides of group 0-N specimens without a pre-delamination have a high degree of coincidence since the middle plane coincides with the neutral plane. In other words, when the specimen does not have a delamination defect, its compression deformation has good continuity and integrity and buckling does not occur. However, obvious differences exist in the stress–strain curves of upper and lower surfaces for the other three types of specimens, such as the No. 2 of the DB group, No. 1 of the SC, and the TC group. The difference between the stress–strain curves of the upper and lower surfaces when the strain gauges were located at the place of the delamination was the largest, such as the No. 1 strain gauges of the SC group. The farther the location of the strain gauge from the defect, the smaller the difference between the stress–strain curves of the upper and lower surfaces.It was found that the difference between the stress–strain curves of the upper and lower surfaces of the 60-SZ-SC group and the 60-SZ-DB group was the smallest among several groups of specimens with the same defect type. On the contrary, the difference in the stress–strain curves of upper and lower surfaces was the largest for the specimens without interlayer toughening. This indicates that the interlayer properties have an appreciable influence on the delamination defects and thus affect the mechanical behavior of laminated composites. However, the stress–strain curves of the upper and lower surfaces of TC group were not significantly changed whether the particles were included or not, which preliminarily indicated that the particle toughening could not change the local deformation mode of TC group.In order to further study the impact of delamination on the compression deformation of laminated composite materials, the out-of-plane displacement field during compression was monitored by using the DIC, as shown in Through the whole process of monitoring of the out-of-plane displacement field by DIC, we found that a large out-of-plane deformation region existed, where the out-of-plane deformation was significantly larger than that of other intact positions of the specimen around the embedded defects for all types of specimens. The TC group specimen had a large out-of-plane deformation region at the initiation deformation stage. The large out-of-plane deformation regions of the DB group and the SC group specimens gradually expanded during the compression process, the possible reason might be that the internal delamination area of the two specimens was also gradually expanded during the compression process. Local buckling would make the material reach the deformation limit faster and reduce the compressive strength of the laminated specimens.The test results of the 0-N group in which the specimens were without any special treatment were used as the reference for analyzing the ones in other working conditions. Since the location of the embedded defect is close to one side of the specimen, the side close to the embedded delamination of the specimen is called “side A” and the one away from the defect is called “side B” for convenience in discussion. Observing the damage morphology of side A shows that the embedded delamination of most specimens in the SC group can be seen after the test. The embedded delamination divided the specimen into two parts along the thickness direction, resulting in discontinuous cracks in the upper and lower parts or even completely different characteristics and trends of cracks. For example, the crack in the upper part of the 0-SC group in Similar to the SC group, the specimen of the DB group also had a sudden load descending phenomenon during compressive loading, as shown in From Up to now, the compression failure mode of various specimens and the influence of different types of delamination defects on the compressive mechanical behavior of materials have been preliminarily analyzed. A sudden descending of load in the compression process of the DB group and the SC group specimens was observed. Previous experience showed that the energy release caused by the damage might lead to the sudden decline of the load. The more serious the damage was, the more intense the load decline was. However, observable surface damage was not seen before the complete failure of the specimen and only a popping sound similar to the one caused by the crack extension was heard during the compression test. Therefore, it is hypothesized that the sudden descending of load in the compression process of the DB group and the SC group specimens was due to the propagation of delamination defects. To verify this speculation, specimens containing different types of defects in the two groups with or without particles were selected for C-scanning. The results are shown in To unify the expression, the area of delamination in the specimen after compression was called the final delamination area. The area of embedded delamination was called the initial delamination area. The part obtained by subtracting the latter from the former was called the secondary delamination.It is seen that a great difference exists in the load response and the final failure form if the types of delamination defects contained in materials are different. In order to more intuitively reflect this difference, the residual compressive strength of materials of different kinds of specimens is compared, as shown From It was also found that when the steel particles were used to toughen the interlayer of specimens in the SC group and the DB group, the improvement of the residual strength brought by the interlayer toughening was very significant. For the SC group, the residual strength of the 30-SZ-SC specimen was the largest and about 29.37 MPa higher than that of the 0-SC group, and the increase rate was close to 10.00%. The residual strength of the specimens in a 60-SZ-SC group increased by 25.05 MPa, which is slightly smaller than the one in the 30-SZ-SC group. When the particle density was the same, the residual strength of the specimens in the SZ specimen was often higher than that of the SJ specimen. It shows that the toughening with stainless steel particles can indeed improve the compressive residual properties of SC group specimens, and the magnetic guidance method can further improve this strengthening effect.The strength of the specimens in the 0-DB group was 18.69% lower than that in the 0-N group, close to the proportion of strength reduction of the 0-SC and the 0-TC group. When a certain amount of stainless steel particles were added between layers and guided by the magnetic (specimens in DB group), the residual strength increased very significantly. The average strength of the specimens in the 60-SZ-DB group reached 285.36 MPa, only 4.77% lower than that of the 0-N group.However, the interlaminar toughening by adding stainless steel particles had little effect on the improvement of compressive strength for the TC specimens, and the difference between the largest and smallest strength was less than 2.00%.Based on the comparison and analysis, one may conclude that the initial delamination area in the laminated composite cannot be directly used as evidence to judge the residual compressive strength since delamination propagation may occur during the compressive process. The final delamination area should be used as evidence to judge the residual strength of laminated composites.In this section, the reason the in-plane compression strength can be improved by increasing the interlaminar toughness is given. First of all, the enhancement of the material properties by the particles themselves should be excluded, because the particles are only located between ply-3 and ply-4, which is not enough to cause a large difference in properties from the perspective of volume content. Moreover, if it is due to the in-plane reinforcement of the particles, the strength of SJ group should be higher than that of SZ group, because randomly distributed particles can enhance the compression axis better, but the SZ group should be reinforced in the thickness direction, which is inconsistent with the test results.In addition, according to the damage morphology of the specimens and the internal C-scan images, one can find that some specimens have the propagation of delamination from its initial state (embedded PTFE film) in the compression process, such as specimens in SC group and DB group. From Therefore, the interlaminar fracture toughness has become the most important factor affecting the delamination growth. The enhancement of toughness would make the crack growth more difficult, and thus limit the expansion of the defect range and reduce the final impact of delamination on the compressive properties of the laminated composites.As shown in It can be seen that the toughening method can effectively improve the interlaminar fracture toughness of materials. Among them, the interlaminar mode II fracture toughness of the 30-SZ group increased by 87.72%, which is significantly higher than that of the other groups and reached twice that of the SJ group specimens with the same particle density. In addition, for mode I fracture toughness, the enhancement rate of the 60-SZ group was the highest, reaching 81.88%, while the enhancement rate of the 30-SZ was the highest in other working conditions, but it was still less than 30.00%. In general, under the same particle density, the fracture toughness enhancement rate of the SZ group was much higher than that of the SJ group, which indicates that magnetic guidance, as an auxiliary means of particle arrangement direction, plays a very significant role in improving the interlaminar fracture toughness.It is seen that the mode II fracture toughness of the 30-SZ group and the mode I fracture toughness of the 60-SZ group were increased by more than 80%, much higher than the corresponding ones of other types of specimens, while the mode I fracture of the 30-SZ group and the mode II fracture toughness of the 60-SZ group were much lower. The results may be helpful to identify whether a certain type of delamination defect was affected by mode I or mode II fracture toughness.COV) was introduced to measure the correlation between the residual compressive strength and mode I/II fracture toughness for different types of specimens. Test results are listed in The covariance . Furthermore, the residual strength sF2 corresponding to type II point determines the final residual performance of all materials whose initial delamination area values are within the FTI, and thus type II point is named as the “strength target point” (STP).There are two intersection points in From the above discussion, to effectively improve the delamination damage tolerance of the material, the delamination area corresponding to DCP should be as large as possible and the one corresponding to STP should be reduced to as small as possible. This can not only reduce the probability that the delamination area value is just located in the FTI , but also ensure less strength reduction even if the secondary growth of delamination is inevitable.D is always larger than the sF, and delamination does not propagate during the compression. However, in this case, interlayer toughening is not effective in improving residual strength. This is similar to the TC group tests because the initial delamination areas of the TC group specimens are already larger than the area value A2 corresponding to the STP, which means that delamination does not precede compression damage. Therefore, the increase in interlaminar toughness in this case does not affect the compression strength of this class of materials.From the characteristics of the curves, the shorter the FTI or the closer the curve (i) in D curve, change the intersection position, and enhance the residual performance. Furthermore, considering that D should be a function influenced by multiple variables, other conditions may affect the characteristics of the curve, such as the position of the delamination defects in the thickness direction, the number of delamination defects, and the geometry of the delamination.However, for specimens with suitable delamination areas, such as the DB and SC groups, the interlayer toughening method can effectively improve the residual properties of materials. In other words, the toughening of the interlayer can change the characteristics of the Carbon fiber laminates with three types of delamination defects, i.e., the deeply buried delamination, the through-width delamination, and the surface delamination, were successfully manufactured to experimentally study the relationship between the residual compressive properties and the interlayer toughness, as well as the type of delamination defects. A new magnetically guided stainless steel particle interlayer toughening method was used to enhance the interlayer toughness. A dynamic damage relationship was proposed based on the test results. The experimental results showed that the surface delamination reduced the compressive strength of the laminates most with 20% reduction, while the percentage reduction of the compressive strength of laminates with deeply buried delamination and through-width delamination was slightly lower than that of the surface delamination.The improvement of interlaminar toughening can effectively improve the residual compressive properties of some laminated plates containing delamination. Improving the mode I fracture toughness can improve the residual strength of the specimens containing the embedded delamination. The strength reduction decreased from 55.98 MPa to 14.01 MPa when the mode I fracture toughness was increased by 81.88%. Improving the mode II fracture toughness can enhance the residual strength of the specimens with the surface delamination. The strength reduction decreased from 60.23 MPa to 30.86 MPa when the mode II fracture toughness was increased by 87.72%.In addition, it was found that generally the property degradation caused by secondary delamination should be considered, but if the delamination reached a certain level, the property degradation caused by the secondary delamination growth was negligible since the delamination area did not increase anymore, as evidenced by the test results of the TC group. The significant increase in residual strength in the DB and SC groups indicated that increasing the fracture toughness to prevent secondary delamination was an effective means of increasing the delamination damage tolerance of the laminate. A magnetically guided stainless steel particles interlayer toughening method could effectively inhibit delamination growth and thus improve the residual properties of laminates.


It was found that sodium stannosilicate (Na8SnSi6O18) was easily formed due to the main gangue of quartz in cassiterite concentrates, which was almost insoluble and decreased the quality of Na2SnO3. The formation and transitions of Na8SnSi6O18 in the SnO2–SiO2–Na2CO3 system roasted under a CO–CO2 atmosphere were determined. The results indicated that the formation of Na8SnSi6O18 could be divided into two steps: SnO2 reacted with Na2CO3 to form Na2SnO3, and then Na2SnO3 was rapidly combined with SiO2 and Na2CO3 to form low melting point Na8SnSi6O18. In addition, Na8SnSi6O18 can be decomposed into Na2SiO3 and Na2SnO3 by using excess Na2CO3.To produce Na Previoumosphere ,8,9,10. mosphere . In addimosphere ,12,13,142) is the primary source of tin. It is naturally formed by magmatic-hydrothermal processes and occurs in granite pegmatites, quartz veins, greisens associated with granites, highly fractionated granites, as well as placer deposits [2 in tin concentrates being as high as 8 wt.% [Cassiterite  under air atmospheres. However, the authors’ group found in previous research that cassiterite (or SnO2) could readily react with Na2CO3 under an appropriate CO–CO2 atmosphere. In the roasting process, the CO gas molecules were firstly adsorbed on the SnO2 surface and then combined with the bridging oxygen so that some oxygen vacancies were formed. These vacancies were replenished by the active oxygen anions in Na2O, which was the decomposition product of Na2CO3 roasted over 851 °C. These processes accelerated the formation of Na2SnO3 [Cassiterite concentrate, as reported, seldom reacts with soda  in the raw material has a significant effect on the phase transformation of SnO2 during the soda roasting process [2SnO3 and Na2SiO3, which are freely soluble in NaOH solution. It was found that Na8SnSi6O18 was easily formed and was almost insoluble during the leaching process, which decreased the recovery of tin [2–SiO2, which was investigated during the cassiterite reduction smelting process and flat glassmaking method [2 was an acidic oxide, while it transformed into SnO, an alkali oxide, during the reduction process. However, no studies have mentioned the reactions in the SnO2–SiO2–Na2CO3 system, especially under a CO–CO2 atmosphere.Our previous studies have found that the quartz , scanning electron microscopy and energy dispersion spectroscopy (SEM–EDS), thermogravimetric and differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FTIR), etc. Based on our previous studies, SiO2) and quartz (SiO2) were found in the XRD pattern of the pretreated cassiterite concentrates. In addition, the contents of Sn and Si were determined to be 62.93 wt.% and 3.66 wt.% by ICP-AES, respectively, while impurities of Ca, Fe, Mg, Al and S were not detected. Moreover, the analytical reagents of SnO2, SiO2, Na2CO3, Na2SiO3 and Na2SnO3·3H2O  used in this study had a purity of over 99.5 wt.%, and all the samples were pre-ground to fully pass through a 0.037 mm sieve. The gases CO, CO2 and N2 had a purity of 99.9 vol%.The cassiterite concentrates  used in this study were pretreated by oxidizing roasting and acid leaching processes to remove impurities ,13. As s2) atmosphere have been described in our previous study [2SnO3 tests were conducted in a water bath at 40 °C with a content of 0.05 mol/L NaOH solution. Finally, the leaching solution was filtered and prepared to determine the formation efficiency of Na2SnO3. The residues were washed with distilled water to identify the phase constituents as follows:L is the formation efficiency of Na2SnO3, M is the weight of the roasted samples (g), W is the grade of Sn in the roasted samples (%), C is the mass content of Sn in the leaching solution (mg/mL) and V is the volume of leaching solution (mL).The experimental procedures in this study mainly include the roasting and leaching process, where the details of the roasting process under a 15 vol% CO/ equipped with an EDAX energy dispersive X-ray spectroscopy (EDS) detector . Fourier transform infrared spectroscopy (FTIR: Nicolet 8700) in the range of 400–4000 cm−1 was applied to determine the chemical bands of the roasted samples in transmission mode. TG-DSC analyses of samples were performed using a thermal analyzer  in the temperature range of 25–1200 °C with a heating rate of 10 °C/min in an Ar atmosphere, and a platinum crucible was used with 50 mg samples for each test. The content of Sn in the solid material and the aqueous solution was determined using inductively coupled plasma atomic emission spectroscopy . For each ICP test, a certain mass or volume of samples was first dissolved in H2SO4–HF solution system, and the solution was set to a constant volume of 100 mL. Then, the solution was tested using ICP, and the Sn content in the raw solid material and the aqueous solution were calculated. The morphological evolution of the roasted samples was monitored by an in situ high temperature thermal analyzer .The phase constituents of the samples were identified by X-ray diffraction XRD (Cu-target Bruker D8 Advance), with a step of 0.02° at 10 min2CO3/SnO2 mole ratio of 1.5, etc. [.5, etc. ,21. A Sn2SnO3 and Na2SiO3, which verified the high leaching efficiency of Sn and Si. In particular, the characteristic peaks of Na8SnSi6O18 were found in the leaching residues of 2 was observed as well. It is seen from 2SnO3 . Hence, it can be inferred that Na2SnO3 may be an important intermediate during the formation of Na8SnSi6O18, as shown in Equation (3). Based on the above phase analysis, in a CO–CO2 atmosphere, there were stronger diffraction peaks of Na8SnSi6O18 than in an air atmosphere. The results demonstrated that the formation of Na8SnSi6O18 in the CO–CO2 atmosphere was much easier than that in the air atmosphere.As shown in 2, SiO2 and Na2CO3 roasted products under a 15 vol.% CO–CO2 atmosphere, as depicted in FTIR analysis was utilized to illustrate the phase transformation of SnO−1 was assigned to Si=O stretching vibrations, and vibrations at 1076 cm−1 and 932 cm−1 correspond to Si-O-Si bonds [2. Simultaneously, the increase in Si-O-Si bonds and Sn-O-Si/Si-O-T bonds  [The peak at 1485 cmSi bonds ,26. The 49 cm−1) ,26,27,282SnO3 and Na2SiO3 were generated along with Na8SnSi6O18, as shown in Equations (2) and (4), then both intermediate products were taken into consideration to reveal the reaction path for the formation of Na8SnSi6O18. SnO2 or SiO2 was first mixed with Na2CO3 at a mole ratio of 1:1 and then roasted at 875 °C under a 15 vol.% CO–CO2 atmosphere for a certain period of time. The XRD analysis of the roasted products is shown in The results in 2 and Na2CO3 (Equation (2)) proceeded much more quickly; Na2SnO3 was the main phase in the roasted products, and almost no diffraction peaks of SnO2 were found after roasting for 15 min. In contrast, the formation rate of Na2SiO3 was slow in the solid-state, and the diffraction peaks were uncertain in As shown in 2SnO3·3H2O, Na2CO3 and SiO2 (AR reagent) with a molar ratio of 1:3:6, as shown in Equation (5), and Na2SiO3·3H2O and SnO2 with a molar ratio of 6:1 as shown in Equation (6). Then, TG-DSC  and XRD analysis were used to determine the possible reactions in the two designed systems of Na2SnO3–SiO2 and Na2SiO3–SnO2, and the results are displayed in In view of further verification, two kinds of mixed samples were prepared as follows: Na2SnO3·3H2O and Na2CO3  [2 gas. In addition, the XRD results in 2SnO3 can be found, which illustrates that Na2SnO3 in the raw materials is converted to Na8SnSi6O18 completely, as shown in Equation (5). On the other hand, the results in 2 and Na2SiO3 (in As shown in l water) . After t2SiO3 in b, which 8SnSi6O18 during the roasting process, Na8SnSi6O18 was synthesized based on our previous study [2CO3: SnO2: SiO2 were mixed as mole ratio of 4:1:6, with a roasting temperature of 1000 °C and roasting time of 360 min. The XRD pattern of synthetic Na8SnSi6O18 is shown in 8SnSi6O18 was well matched with the PDF standard card of No. 85-0532, and there were no diffraction peaks of impurities. The TG-DSC analysis of Na8SnSi6O18 is given in 8SnSi6O18 was stable during the heating process, while a phase transition occurred in the temperature range of 800–850 °C with an endothermic peak at 825.6 °C in the DSC curve. A further test to determine the melting behavior of Na8SnSi6O18 using in situ high temperature thermal analysis is shown in 8SnSi6O18.To find a possible transition process of Naus study . In this8SnSi6O18 was much lower than that of Na2SiO3/Na2SnO3, as shown in Equations (2) and (4). The reactions between Na8SnSi6O18 and Na2CO3 were discussed in the case of excess Na2CO3 dosage. Then, Na8SnSi6O18 and Na2CO3 were mixed at a mole ratio of 1:5, and TG-DSC analysis was conducted. The TG-DSC results and the XRD patterns of the roasted products are shown in Based on the above results, it was found that the mole ratio of Na in Na2CO3 was 851 °C, and it can be inferred that the mass loss was attributed to Na2CO3 decomposition in the presence of Na8SnSi6O18. It is noteworthy that, as found in 2SiO3 and Na2SnO3 were the main phases in the final TG products, and no diffraction peak for Na8SnSi6O18 remained, which indicated that Na8SnSi6O18 easily reacted with excess Na2SnO3. A possible reaction was proposed, as shown in Equation (7), based on conservation of mass.According to 8SnSi6O18 was investigated, and the Na2CO3/Na8SnSi6O18 mole ratio was fixed at 3:1, as in Equation (6). 2CO3/Na8SnSi6O18 mixed samples roasted in the temperature range of 800–900 °C with a time of 30–120 min.To verify the above analysis, the effect of roasting temperature and roasting time on the phase transformation of Na8SnSi6O18 at 800 °C, while the diffraction peaks of Na2SiO3 and Na2SnO3 were uncertain. The structural diffraction peaks of Na8SnSi6O18 weakened and then vanished when the temperature exceeded 850 °C. 2SiO3 appeared and Na8SnSi6O18 decreased at 30 min, and then the peaks of Na8SnSi6O18 gradually decreased and disappeared as the roasting time was prolonged to 90 min and 120 min. Na2SiO3 and Na2SnO3 were the final roasted products expressed as Equation (7).As shown in 2 and SiO2) into freely soluble materials (Na2SnO3 and Na2SiO3). However, Na8SnSi6O18 was inevitably generated during the roasting process, which was almost insoluble in the leaching process and markedly decreased the recovery of Sn. Based on the above results and our previous studies, the reaction mechanism of the SnO2–SiO2–Na2CO3 system and the formation of Na8SnSi6O18 can be summarized as follows in During the soda-roasting process of cassiterite concentrates, the overriding aim was to synchronously promote the transformation of stubborn minerals (SnO2 reacted with Na2CO3 to form Na2SnO3 as shown in Equation (2). Meanwhile, part of SiO2 also reacted with Na2CO3 to form a small amount of Na2SiO3, see Equation (4). Nonetheless, the reaction rate was much lower than that of Equation (2). Then, Na2SnO3 reacted immediately with Na2CO3 and SiO2 to form Na8SnSi6O18 as shown in Equation (5), and Na2SnO3 was the key intermediate during the formation of Na8SnSi6O18, while the reaction between Na2SiO3 and SnO2 was impossible. The melting point of Na8SnSi6O18 was measured at 825 °C, which was much lower than that of other materials in the SnO2–SiO2–Na2CO3 system. Thus, Na8SnSi6O18 was always formed accompanied by SnO2 and invariably closely wrapped around SnO2 particles, which blocked the contact between SnO2 and Na2CO3. Therefore, the formation of Na2SnO3 was significantly inhibited once Na8SnSi6O18 was present. In addition, Na8SnSi6O18 is an unstable compound that can react with excess Na2CO3 (Equation (7)) as the roasting temperature and time increase.First, SnO2 atmosphere, the formation of Na8SnSi6O18 in the SnO2–SiO2–Na2CO3 system affects the quality of sodium stannate products. To solve this problem, the effects of Na8SnSi6O18 formation on the product quality were investigated in this study, and the following conclusions were obtained:2CO3 and SnO2/SiO2 proceeded simultaneously during the roasting process, while the formation of Na2SnO3 was promoted under a CO–CO2 atmosphere. Then, Na8SnSi6O18 was easily formed once Na2SnO3 appeared; nonetheless, the reaction between Na2SiO3 and SnO2 was impossible;The reactions between Na8SnSi6O18 is only 825 °C, which is much lower than that of Na2CO3, Na2SnO3 and Na2SiO3 in the SnO2–SiO2–Na2CO3 system. Na8SnSi6O18 closely wrapped around the SnO2 particles and restrained the reaction between SnO2 and Na2CO3;The melting point of Na8SnSi6O18 is an unstable compound, and the reaction between Na8SnSi6O18–Na2CO3 can proceed as Na8SnSi6O18 + 3Na2CO3 = 6Na2SiO3 + Na2SnO3 + 3CO2. The reaction was controlled by higher temperatures of above 800 °C as the roasting time was prolonged.NaDuring the process of sodium stannate preparation from cassiterite concentrate under a CO–CO