Spin-lock based functional magnetic resonance imaging (fMRI) has the potential for direct spatially-resolved detection of neuronal activity and thus may represent an important step for basic research in neuroscience. In this work, the corresponding fundamental effect of Rotary EXcitation (REX) is investigated both in simulations as well as in phantom and in vivo experiments. An empirical law for predicting optimal spin-lock pulse durations for maximum magnetic field sensitivity was found. Experimental conditions were established that allow robust detection of ultra-weak magnetic field oscillations with simultaneous compensation of static field inhomogeneities. Furthermore, this work presents a novel concept for the emulation of brain activity utilizing the built-in MRI gradient system, which allows REX sequences to be validated in vivo under controlled and reproducible conditions. Via transmission of Rotary EXcitation (tREX), we successfully detected magnetic field oscillations in the lower nano-Tesla range in brain tissue. Moreover, tREX paves the way for the quantification of biomagnetic fields. According to analysis of data of previous years, taking into account related suicides, mental disorders could even have a significantly more severe impact2. An increase in the prevalence of mental disorders as a result of the influence of the COVID-19 pandemic is considered likely1. One of the great goals of current research is to understand the functional principles of the brain, so that those disorders can be studied to understand the underlying mechanisms and to improve their treatment.According to the 2019 Global Burden of Diseases, Injuries, and Risk Factors Study, mental disorders were among the ten most common causes of global burden of diseases, as measured by disability-adjusted life-years3. Consequently, developing a novel method that both meets the requirements of spatiotemporal resolution and direct detection of neuronal activity is of great importance for the progress of brain research. A young branch of MRI research is therefore addressing direct mapping of neuronal activity based on spin-locked MRI techniques4.In recent years, brain imaging has made great progress. For example, the anatomical structures of the brain are well known from in vivo measurements such as diffusion-weighted magnetic resonance imaging (MRI). Diagnostics currently well-established for functional investigations include techniques that directly measure neuronal activity, such as electroencephalography (EEG) and magnetoencephalography (MEG). Indirect measurement via hemodynamic response is provided by blood oxygenation level dependent (BOLD) functional MRI (fMRI). However, for the precise investigation of functional connectivity and in-depth analysis of brain activity, noninvasive methods with improved spatial and temporal resolution compared to existing methods are required2* or a phase imposition5. Since the main magnetic field in clinical scanners is in the range of 1.5…7 T, the system is resonant to oscillating fields in the RF range  and is therefore insensitive to neural oscillations in the Hz range. In a system with a field strength of about ≈ 1 μT, resonant energy absorption of fields with frequencies at the magnitude of Hz is possible6. In such low-fields, however, the magnetization M0 in thermal equilibrium is very small and thus poor signal-to-noise-ratio (SNR) is to be expected. In 2008, Witzel et al. proposed a completely new approach  for detecting tiny oscillating magnetic fields in the Hz range7. Instead of using a low-field device, Witzel exploited the rotary saturation effect first described by Redfield in 19558. Within the so-called spin-lock (SL) condition, in the presence of a continuous wave RF pulse rotating at the Larmor frequency, sensitivity to magnetic field fluctuations in the low frequency range can be created8 while maintaining high SNR at clinical field strengths9. Here, the resonance condition can be shifted by adjusting the SL field strength. In subsequent studies, a modification of the SIRS sequence was proposed, which shows a significantly improved signal scaling behavior and provides sensitivity to the oscillation phase11. Most importantly, this technique is not based on magnetization saturation, but on excitation of magnetization during spin-lock interaction. This concept, which we refer to hereafter as Rotary EXcitation (REX), holds great potential for the direct detection of neuronal activity4, since ultra-weak magnetic oscillations act like pseudo RF pulses in the rotating frame and thus can be detected via sinusoidal signal variations in a positive contrast evaluation (REX weighted contrast). A brief summary of the available studies on rotary saturation and rotary excitation targeting fMRI is provided in the Supplementary Material  technique19 has already been applied. However, the influence of such compensation techniques on the measured REX signals has not been thoroughly investigated so far and furthermore approaches like rotary-echo SL (RE-SL)20, balanced SL (B-SL)21 and adiabatic excitation22, have not been considered. In particular, there is evidence of a strong dependence of REX signals on the SL parameters used 23, which has not yet been considered for compensated REX techniques.One of the major challenges in employing the REX technique to detect neuronal activity is its susceptibility to field inhomogeneities15, which need precise calibration and RF shielding within the MRI room. Furthermore, accurate synchronization with the MRI sequence is required. These circumstances slow down technical development and pose a major challenge to reproducibility. In addition, new sequences cannot be tested on humans under in vivo conditions, as this would usually require certification of the developed hardware. Thus, in vivo validations under controlled conditions were not performed and the highly challenging measurements of neuronal biomagnetism have been attempted directly within the fMRI setup4.Another major challenge is the experimental validation of new SIRS or REX based methods. Since the interaction of a SL pulse with a weak magnetic field oscillation has to be measured, phantom experiments have been performed so far in which the existing MRI setup had to be equipped with additional hardware. Examples include field-generating loop-coils or dipole electrodesIn this study, the basic REX technique is advanced in three steps. First, we investigate how SL compensation techniques can be used to robustly measure and quantify ultra-weak magnetic field oscillations to achieve direct detection of biomagnetic fields. Thereby, the detected REX signals could potentially be increased while reducing the influence of static field inhomogeneities. The different preparation characteristics of most common compensation techniques were examined by Bloch simulations. Particular attention was paid to the critical parameter of SL duration. Second, we propose a novel method for transmitting the rotary excitation effect onto the object under investigation . Using ultra-weak gradient waveforms generated by the built-in MRI gradient system, the proposed method allows to mimic brain activity by transmitting artificial magnetic fields onto the living brain tissue. This not only enables reproducible, rapid validation measurements in phantoms but also a comparison of the compensation techniques under in vivo conditions in humans. Third, we demonstrate how this new technique can pave the way for quantification of biomagnetism, as tREX enables signal calibration in vivo.24 based on Matlab . The measurements were carried out on a clinical 3.0 T scanner  using a 20-channel head coil and the standard gradient system .In the present study, a thorough investigation of the rotary excitation effect for established spin-lock compensation techniques was performed using Bloch simulations, phantom validations and in vivo experiments in human brain tissue. To allow reproduction of our experiments, all measurements were performed using the new tREX concept. Furthermore, the MRI sequences used were implemented in the hardware-independent open-source Pulseq framework0 and standard continuous wave spin-lock (S-SL), no compensation20rotary-echo spin-lock (RE-SL), 0 and 19composite spin-lock (C-SL), single refocused B0 and 21balanced spin-lock (B-SL), double refocused BSpin-lock preparation modules are commonly classified by their compensation approaches for B1ρ quantification that adiabatic excitation prior to spin-locking is highly beneficial as it allows preventive compensation of 22. An identical 0 inhomogeneities  in the field of view (FOV) within an offcenter slice in distance stim = 50 Hz were aspired in An essential part of the present study is the realization and validation of REX experiments without using external hardware such as loop-coils or dipole-electrodes for field generationThe tREX concept can also be carried out with the x- or y-gradient or with a superposition of all three gradients in an oblique slice. Here, tREX benefits from the very precise control of gradient coils and enables the full implementation of REX experiments within the Pulseq framework.0 and 25. The basic concepts can be adopted for REX. In contrast to Ueda25, the Bloch equations, which are described for the REX case by a system of nonlinear differential equations, were solved numerically. A Runge–Kutta method  implemented in Matlab was used for this purpose. Details of the simulation can be found in the Supplementary Material  was dissolved in demineralized water at a concentration c = 0.75% and doped with 0.25 mmol/L Gd-DTPA . The gel was prepared in a cylindrical sample tube .26 in the Agarose phantom. Sinusoidal gradient waveforms  were generated. The relative phase of the oscillating gradients was varied in the range 0 … 2π (10 linearly spaced steps). For the measurement of the gradient trajectories realized by the setup, the phase evolution was recorded in a thin offcenter slice (2 mm thickness) at a distance of 25 mm from the isocenter for tacq = 30 ms (50 kHz bandwidth). To correct for static off-resonance effects, the observed phase evolution was rectified by a reference scan (tREX gradients switched off). The gradient trajectory was subsequently determined from the discrete derivative of the phase evolution. The results of the trajectory measurements were compared with the set gradient stimuli.In initial preparatory experiments, it was investigated whether the ultra-weak gradient waveforms required for the tREX method can be generated with the standard built-in gradient system. The target was the transmission of magnetic field oscillations with orms Eq.  with a fSL was investigated and compared with the results of the Bloch simulation. Finally, the tSL characteristic was investigated in a ROI (region-of-interest) based evaluation. For imaging of the REX signals, a turbo spin echo (TSE) readout with centric encoding was used in all phantom experiments (TE = 12 ms). Due to the phase encoding, REX experiments with identical relative phases had to be repeated several times. The FOV was 150 × 150 mm2 and the matrix 96 × 96. The turbo factor of the TSE readout was 4, so 96/4 = 24 identical REX preparations were performed for the acquisition of a single REX weighted image. A delay Trec = 1 s was used between the individual preparations with TSE readouts for longitudinal magnetization recovery.For the verification of the rotary excitation effect transmitted by gradient oscillations, a series of experiments was performed in an axial tREX slice  in the Agarose phantom with 0 field homogeneity was adjusted in the tREX slice by an extended 2nd order shimming routine prior to the actual field detection experiments. 0 mapping was performed in the same tREX slice with identical FOV settings for control. Thus, the spatially dependent off-resonances 0 field inhomogeneities, an additional constant gradient was applied in x direction during the SL interaction. The gradient amplitude was varied in different experiments in the range 0 … 32 Hz/cm (5 steps), corresponding to a maximum gradient strength of ≈ 75 nT/mm.In the present study, the B27, in the frontal lobe. B0 and All in vivo experiments were performed in brain tissue of a healthy volunteer. The participant was screened for contraindications to MRI and written informed consent was obtained. The study complied with the Helsinki Declaration on Human Experimentation and was approved by the local institutional ethics board . For the tREX experiment, a slice  was chosen that partly intersects the frontal sinus, which exhibits increased field inhomogeneities2* relaxation and off-resonance effects, short readout durations  were used and the k-space was sampled in four segments using interleaved spirals and ramped flip angles  for slice excitation  were taken into account for the choice of tSL. In the best case measurements, the following tSL values were used: 77.5 ms (S-SL), 70 ms (RE-SL), 80 ms (C-SL), 80 ms (B-SL). For the worst case measurements, the following values were used: 82.5 ms (S-SL), 80 ms (RE-SL), 70 ms (C-SL), 60 ms (B-SL). For each measurement, pixel-wise REX amplitude maps were calculated using the standard deviation  occur at tSL ≈ 60, 100, 140, 180 ms. Thus, the periodic intervals ΔtSL of AREX maxima are: 9.8 ms for S-SL, 19.9 ms for RE-SL, 20.0 ms for C-SL, 40 ms for B-SL. The effect of minima/maxima formation was visually illustrated in the Supplementary Material . The results concerning the influence of the T.6%. The 2 > 0.99). In this range, both amplitude and phase could be set precisely. The mean deviation of the adjusted amplitude was − 1.16%. A waveform with 0.1 nT/mm represents the limit. Here, a slight oscillation with high noise level could still be observed in the trajectory measurement. However, R2 = 0.67 was found this case. Below this limit, no oscillation of the tREX gradient could be detected. Thus, tREX experiments up to 1 nT can be performed within a 10 mm offcenter slice.The validation of ultra-weak gradient waveforms is reported in the Supplementary Material . However, a strong formation of banding artifacts is evident in the REX-weighted images for S-SL, which was significantly reduced for B-SL. All measurements were performed in the expected AREX maximum (according to Bloch simulations). Yet, differences in the calculated AREX maps are evident. B-SL . No significant REX variation was detected in the control measurements (gradient stimulus off). In the calculated AREX map, structures of brain tissue can be roughly distinguished. In two different ROIs, we observed Figure SL choice for B0 and REX maps in Fig. REX were observed near the frontal sinus  and a significant reduction is noticeable for RE-SL near the cranial bone. This is also evident in the box plot in Fig. REX was examined throughout the whole brain tissue. B-SL shows the best overall performance and a clear delineation between best/worst case measurements. The amplitude parameter |a| fitted according to Eq.  of the complex signal fit yielded values: 0.982 ± 0.012 for S-SL, 0.985 ± 0.014 for RE-SL, 0.9907 ± 0.0071 for C-SL, 0.9929 ± 0.0033 for B-SL. The remaining parameters of the fitted maps and the corresponding ΔB0 and The impact of tmentclass2pt{minim2 > 0.99 in each case. Pixel-wise linear regression revealed R2 = 0.9977 ± 0.0094 in a whole brain tissue ROI. In addition, the whole brain tissue was evaluated specifically for small stimuli (REX compared to the reference measurement (stimulus off) was 7.3%. However, significant delineation to the reference signal in the brain tissue ROI was only possible at In the tREX calibration study, a clear linear correlation between the stimulus field strength 12, namely the susceptibility to B0 and 21. Bloch simulations were used to progress the principle understanding of REX and its parameter dependency. The simulation results indicating significantly higher robustness of B0 and In the present work, a basic concept for the direct detection and quantification of neuronal activity by MRI has been advanced in three interdependent steps. The major concerns of the REX technique raised by Coletti2 = 0.67). Thus, an oscillation of 1 nT within the isocenter near slice Δz = 10 mm is currently the limit of feasibility. Above this limit (1 … 20 nT/mm), reliable amplitude control and linearity could be demonstrated and the oscillations show the desired sinusoidal profile (R2 > 0.99). These technical conditions must be considered in tREX experiments especially if measurements are to be performed in more distant offcenter slices. In addition, tREX represents only a simple mimic of the in general spatially complex neuronal fields, because only z-components are generated and phase dispersion within a voxel is not produced.Experimental validation of the tREX waveforms could confirm that ultra-weak magnetic field oscillations can be generated with the standard built-in gradient system. While the timing of the phases is fully adequate for the purpose of the REX experiments, the amplitudes of the oscillations are limited, due to the precision of the hardware components. Ultimately, digital quantization of the electronic gradient control is the lower boundary. Minimum gradients of 0.1 nT/mm could only be just generated, whereby the detected waveforms were extensively noisy  or completely on the y′-axis (minimum condition). This phenomenon was illustrated in the Supplementary Material . This cannot be fully compensated by any of the SL modules considered. Yet, in the simulations and measurements, B-SL indicated broader peaks in the tSL characteristics, which effectively compensates for higher 0 = − 2.3 ± 3.5 Hz), a decrease in AREX was observed at the edge of the phantom. In this region, deviations of the REX values. Another way to increase 18. This may also achieve a broadening of the resonance effect for compensated REX modules. However, it became clear that even B-SL provides only the opportunity for REX detection at off-resonances below ≈ 50 Hz. This is currently a restriction that is particularly relevant for 3D field detection in the whole brain. For separate 2D scans, slice-selective higher order shimming is recommended. Another alternative is to adjust the carrier frequency of the spin-lock pulse to the local Larmor frequency of a specific ROI in the cortex.The present work addressed the question whether dynamic magnetic field oscillations can be measured with a simultaneous compensation of static field inhomogeneities. Bloch simulations verified that B-SL, for example, exhibits a significant increase in Bent Fig. . Despite4, not a true single-shot readout was used, but an interleaved acquisition with ramped flip angles. This step makes the readout less susceptible to off-resonance effects and still provides a quasi-single-shot in the context of the preparation. Thus, the sequence presented in this work can be applied for the detection of neuronal activity, where the relative phase of the stimulus is unknown and full k-space sampling must be carried out for each preparation. Another advantage of this technique is the reduced T2* effect due to the shorter individual readouts. This could also be beneficial for the robust detection of neuronal fields at high field strength, as the influence of the BOLD effect is effectively reduced by shorter spiral acquisition times. A disadvantage of our readout is the additional impact of T1 relaxation between the readouts and potential artifacts due to incorrect flip angles. Here, the use of Shinnar–Le-Roux optimized RF pulses and parallel imaging approaches could be explored for further improvement and acceleration31.The findings of simulation and phantom measurements were used to perform initial proof-of-concept experiments for oscillating magnetic field detection in vivo. Here, a spiral readout was used consistently, generating one REX-weighted image for each preparation. In contrast to the method proposed in0 and REX maps, low offsets of REX oscillation, and the signals are approximately 2π-periodic. Another finding was that RE-SL provided slightly better detection than C-SL in the region near the frontal sinus. This can be explained by the characteristics of the B0 susceptibility, where RE-SL clearly differs from the other modules and shows improved sensitivity at some high offresonance values. However, both in phantom and in vivo, RE-SL shows poor REX sensitivity at the edge of the object which is possibly linked to the Although in vivo REX detection with the simple S-SL module was successful in principle, it was demonstrated that the use of Bmentclass2pt{minimg to Eq. . In brai4, the true limit of sensitivity of the REX technique might be lower than 1 nT and can be further improved in vivo. This important point needs to be investigated in future studies, for example, using t-test statistics and repetitive REX experiments. Further investigations should be carried out whether other physiological processes such as blood flow impact REX detection and whether, e.g., triggered measurements or measurements during breath hold are beneficial. For motion correction, image registration techniques could be adapted from established BOLD fMRI routines33.At present, a major challenge for REX detection lies in relatively high noise of the reference scans. In the reconstruction and evaluation of REX weighted images, the influence of respiration has not been corrected yet, which leads to increased 2 > 0.99) between the artificial stimulus field strength and the measured REX amplitude in vivo. Thus, tREX offers high potential as a calibration technique for the amplitude quantification of biomagnetic fields. A reasonable approach for a REX fMRI protocol would be to measure two AREX maps using tREX at different An important finding of our work is that tREX experiments establish a linear correlation  with flickering stimuli35. Another promising application is the localization of the seizure onset zone in focal epilepsy36. While the expected stimulus frequencies in alpha activity and SSVEPs are below the 50 Hz oscillation used in this work, frequencies > 100 Hz can be expected in focal epilepsy. The stimulus frequency dependent prediction rule of AREX maxima conditions found in this work can serve for optimization of the respective sequence parameters. As the relative phase with respect to the spin-lock is generally unknown, the REX amplitude must be determined by the standard deviation of random phase signals as discussed in12. A potential but technically complex alternative is the simultaneous recording of an EEG for retrospective evaluation and a subsequent detection by the REX fit presented in this work37. In this case, the R2 value of the REX fit could be used for an improved validation and higher statistical significance of the measured amplitudes. For these ambitious goals, the present work provides basic MRI concepts, specific optimization approaches and a pulse sequence that is already fully suitable for in vivo studies.In future studies, to achieve the next step for direct detection and quantification of neuronal fields, concepts for fMRI experiments based on a reliable method for modulating neural oscillations needs to be developed. One option for this is the state-dependent enhancement of alpha waves as suggested inThe present work demonstrates a significant stabilization of spin-lock based detection of ultra-weak magnetic field oscillations. The findings concerning compensated REX modules provide a considerably more robust detection in the presence of field inhomogeneities and enable optimization specific to the stimulus frequency. Furthermore, the novel tREX validation technique allows sequences to be tested in phantom experiments as well as under controlled in vivo conditions. Hereby, the feasibility of magnetic field detection in the low nT range could already be demonstrated in brain tissue. Moreover, tREX could pave the way for quantifying amplitudes of neural field oscillations as robust calibration scans can be performed.Supplementary Information.


The risk of total metachronous advanced neoplasia (TMAN) in patients with serrated lesions (SL) and IBD is unknown. It is also unclear whether colonic inflammation in IBD contributes to serrated neoplasia.Study aim was to compare the risk of TMAN at surveillance colonoscopies in patients with SL and IBD to patients with SL without IBD. We also sought to compare IBD severity in patients with IBD and SL in a colonic area involved with IBD (SL-IA) to patients with IBD and SL in an uninvolved area (SL-UA).A cohort study was conducted. Through pathology database search, we identified 2428 patients with endoscopically resected SL, defined as sessile serrated lesion (SSL), traditional serrated adenoma (TSA) or IBD and serrated epithelial change (SEC), between 2010 and 2019 at the University of Montreal Hospital Center. We included patients aged 45-75 without polyposis syndromes and excluded patients with a history of CRC, first surveillance <12 months after complete index, sigmoidoscopy at index, or no follow-up. Patient files were reviewed for demographic data, IBD severity, and findings at index and follow-up. Follow-up was continued until TMAN or last colonoscopy within 10 years. Primary outcome was the risk of TMAN (defined as advanced adenoma (AA), advanced serrated lesion (ASL) or CRC) in a surveillance colonoscopy within 10 years from index. Secondary outcomes were the risk of metachronous AA and ASL, and IBD severity in SL-IA and SL-UA. Continuous and categorical variables were compared using the student t, Pearson’s chi-squared, or Mann-Whitney tests. We performed univariate and multivariate Cox regressions, with hazard ratios (HR) and 95% confidence intervals.In the metachronous outcomes analysis, 440 patients with SL  were eligible, and 37 with SL and IBD were eligible . Compared to patients without IBD, IBD patients were less likely to have synchronous adenomas , had less SLs ≥10 mm , and had a similar risk of metachronous TMAN (HR=0.92 [0.44–1.90]), AA (HR=0.53 [0.13–2.12]) and ASL (HR=1.03 [0.44–2.41]). In the comparison of SL-UA and SL-IA, 56 patients with IBD were eligible, with 21 having SL-UA  and 35 having SL-IA . Both groups had similar time intervals between IBD diagnosis and SL diagnosis (p>0.05), and similar maximal therapeutic maintenance steps (p>0.05), as well as Mayo/SES-CD scores, serum C-reactive protein, hemoglobin, and albumin, and fecal calprotectin values at index and last colonoscopy (p>0.05).Patients with SL and IBD are not at higher risk of total metachronous advanced neoplasia than patients with SL and no IBD. SLs in IBD should be considered sporadic and undergo endoscopic resection and follow-up similar to non-IBD patients.CIHR, OtherFonds de Recherche du Québec en SantéNone Declared


The palm and date sector is one of the most important sectors in Saudi Arabia. The total number of fertile palm trees in Saudi Arabia is about 31 million. In the production of pitted dates, date molasses, date paste, and date confectionery, a considerable number of date kernels are usually discarded as waste. This study reports experimental investigations conducted to evaluate the potential of waste date kernel ash (DKA), obtained by the calcination of date pits at 800 °C, as a partial cement replacement in concrete. DKA has low silica oxide and does not qualify as a pozzolanic material. The effect of DKA partially replacing the cement and acting as a filler material in concrete was investigated, and its properties were compared with two pozzolanic materials, fly ash (FA) and natural pozzolan (NP). Twelve concrete mixes in which cement was replaced with different proportions of calcined DKA , NP , and FA  were investigated in the experimental program. The properties of DKA, FA, and NP concrete mixes were evaluated in fresh and hardened states, including the heat of hydration, mechanical characteristics, and thermal properties. The results show that replacing cement with 5% date kernel ash increases the compressive strength by 0.42%, 3.2%, and 2.5% at 3, 7, and 28 days, respectively, while the 28-day compressive strength decreases by 2.4%, 5.4%, 16.3%, and 26.69% when the cement is replaced with 10%, 15%, 20%, and 30% DKA, respectively. Date kernel ash concrete mixes with 10%, 20%, and 30% replacement levels demonstrated higher compressive and tensile strengths and lower thermal conductivity, density, and workability when compared to natural pozzolan and fly ash. DKA is a promising partial cement replacement material; nevertheless, additional research is required to assess the durability of DKA in concrete. The date palm and oil palm are the two most widespread palm species. The date palm is most common in Middle Eastern countries, such as Saudi Arabia, Egypt, and the Emirates, as well as in the United States  , while tThe production of dates in Saudi Arabia accounts for 17% of the total worldwide output, making it one of the world’s largest date-producing countries. Saudi Arabia produces around 1.5 million tons of dates annually and has approximately 31 million palms ,7. The u2 and (4.8–8.2%) CaO [The utilization of palm oil fuel ash has, however, been extensively investigated and reported in the literature ,14,15,16.2%) CaO ,20,21,22.2%) CaO ,24, whic.2%) CaO ,26,27, a.2%) CaO . The rep.2%) CaO . The pot.2%) CaO . Many st.2%) CaO ,33,34,35Generally, mineral admixtures, such as natural pozzolan and fly ash, are used to partially replace Portland cement. Several studies in the literature have presented the use of natural pozzolan and fly ash as partial substitutes for cement in mortar and concrete ,37,38,392 to 3000 kg/cm2. The fine aggregate used is locally available dune sand. It has a specific gravity of 2.6% and a water absorption of 0.3 %. The coarse aggregate is a limestone aggregate, with a specific weight of 2.6 and a water absorption of 1.4 %. The gradation of the fine and coarse aggregates is shown in In this study, concrete mixtures were made using ordinary Portland cement (OPC) Type 1 from the Qassim cement plant, Buraiah, Saudi Arabia. 3 and a water–cement ratio of 0.38. In Mix Nos. 2 to 6, varying percentages of thermally treated date seed powder (DKA) were used in place of cement . In Mix Nos. 7 to 9, fly ash was used in place of cement at various percentages . In Mix Nos. 10 to 12, cement was replaced with 10%, 20%, and 30% natural pozzolan. The ratio of water to binder was fixed for all mixtures at 0.38. In this study, a total of twelve different types of concrete mixtures were prepared. The reference mix (Mix 1) had an OPC content of 480 kg/mThe date kernels were cleaned and ground before being placed in a graphite crucible. The crucible has a height of 14 cm and a diameter of 14.5 cm and can withstand temperatures up to 1600 °C. The crucible was then heated to 800 °C within 2 h in a closed-vessel oven. The temperature was then maintained at 800 °C for 2 h before gradually cooling to 30 °C at a rate of 50 °C/h. 2) and calcium oxide (CaO), as shown by the XRF analysis  was used for the X-ray fluorescence experiment to determine the elemental compositions of DKA, NP, and FA see a. The saanalysis . As the , as shown in The adiabatic heat of hydration of DKA and other materials was determined using the semi-adiabatic calorimeter iQDrum The thermal properties of DKA-, FA-, and NP-based concrete mixes were determined at 3, 7, and 28 days of age using the TEMPOS meter . Thermal conductivity, resistivity, and heat capacity were measured for the selected concrete mixtures. The thermal properties were measured with the meter using a heat pulse approach. A heating needle and a thermal sensor were inserted into the concrete, and then heat was applied for 60 s to the heating needle and, simultaneously, the concrete temperature was measured using the thermocouple. For the accuracy of measurements, good thermal contact needs to be ensured between the sensor and the concrete ,44. A piThe overall quality of the concrete and the identification of voids or cracks that may be present in the concrete matrix can be determined using the UPV method ,48. An uWorkability refers to how easily and consistently a freshly made concrete mix can be poured, compacted, and finished. The workability of concrete improves as the water–cement ratio increases and is generally measured by conducting slump tests on fresh concrete ,50. The 3 and 1842 kg/m3, the concrete is classified as “light” [A reduction in the density of the concrete leads to a lightweight overall structure. When the density of the concrete is between 1361 kg/m “light” . The mea “light” . It is eThe evolution of the adiabatic heat of hydration over time for the investigated concrete mixtures (12 mixes) is shown in cm is the weight of cementitious material per cubic meter (kg/m3), γ is the unit weight of concrete (kg/m3), and c is the specific heat capacity (KJ/m3.°C). The adiabatic temperature rises for the investigated concrete mixes are shown in The heat of hydration obtained from semi-adiabatic calorimetry can be converted to the temperature rise under adiabatic conditions using the following equation ,54:(1)ATThe maximum rate of change in the heat of hydration and the rate of the temperature rise measured for the twelve concrete mixes are shown in The TEMPOS meter was used to determine the thermal conductivity, resistivity, and specific heat capacity of concrete mixtures at 3, 7, and 28 days. The thermal conductivity, resistivity, and specific heat capacity of concrete mixtures investigated in this study are shown in 3 K at the ages of 3, 7, and 28 days, respectively. The mixture with 30% DKA had the highest volumetric specific heat (2.75 MJ/m3 K).The maximum thermal resistance was measured for the concrete mix with 30% DKA at the age of 28 days with a value of 85.6 °C.cm/W. Compared to the FA and NP mixes, the thermal resistance of the DKA mixes is higher, as can be seen in When cement was replaced with 30% FA, the specific heat capacity increased by 17.88%, 17.19%, and 14.28% at 3, 7, and 28 days, respectively , HoweverThe compressive and splitting tensile strengths of the twelve concrete mixtures were measured at 3, 7, and 28 days. The replacement of cement with 10% DKA led to reductions in compressive strength of 6%, 5.89%, and 2.35% at 3, 7, and 28 days of age, respectively, whereas 10% NP and 10% FA reduced the compressive strength by 26.87%, 31.21%, and 31.19 and 9.85%, 11.39%, and 7.67% at the same ages, respectively. In general, the replacement of cement with 10%, 20%, and 30% DKA, NP, and FA resulted in a decrease in compressive strength of varying percentages, as shown in The tensile strength of concrete mixtures at 3, 7, and 28 days of age was measured and is shown in The experimental results show that the calcined date kernel ash has a strong potential for use as a partial replacement of cement in concrete with up to 30% without significantly affecting the hardened properties of concrete. At the 30% DKA replacement level, the 28-day compressive strength is 25.2 MPa, reflecting a decrease of 26.69% compared to the control OPC mix. The DKA concrete outperformed FA and NP concrete in terms of compressive and tensile strengths at ages of 3, 7, and 28 days for the 10%, 20%, and 30% replacement levels.DKA was found to generate less heat of hydration compared to NP and FA at 10% and 20% replacement ratios, respectively, while FA generated the least heat of hydration at a 30% replacement of cement. The concrete mix containing 30% DKA had a slower rate of heat and temperature rise when compared with the concrete mixes containing 30% FA or 30% NP.The concrete mixes with DKA at 10%, 20%, and 30% replacement have a lower density, lower thermal conductivity, higher thermal resistivity, and higher specific heat compared to the mixes with NP and FA at the same percentages.In conclusion, DKA is a promising new partial cement replacement material, and further research is needed to investigate the durability of DKA concrete.This study investigated the feasibility of using date kernel ash (DKA) as a partial cement replacement material. A comparison was made between DKA, NP, and FA in terms of the evolution of the heat of hydration and thermal and mechanical properties. The following conclusions can be drawn from the experimental results:


Enterobacterales. Each chip provides a colored readout with actionable susceptibility classification of three antibiotics, thus maximizing the chances of identifying a viable therapy. We verified the technology on thirty bacterial strains with two dyes using six clinically relevant antibiotics. We demonstrated that the dried tests are stable for one month and can be incubated in a rechargeable coffee mug that reduces the need for external infrastructure.The increasing prevalence of antibiotic resistance threatens to make currently treatable bacterial diseases deadly again. As drug resistance rises, antibiotic susceptibility testing needs to adapt to allow for widespread, individualized testing. Paper-based diagnostics offer low-cost, disposable alternatives to traditional time consuming and costly in-house methods. Here, we describe a paper-based microfluidic device, called the Bac-PAC, capable of categorizing the antibiotic susceptibly of individual strains of Carbapenem-resistant  Carbapenem-resistant Enterobacterales (CRE) is a highly antibiotic resistant group of organisms dubbed the “nightmare bacteria” because of their estimated annual deaths, prevalence in hospitals, and rapid transfer of antibiotic resistance genes2. Many experts in AMR broadly recommended that antimicrobial susceptibility testing (AST) be performed on an individual basis so that personalized treatments can be prescribed4. This would prevent the misuse of last-line antibiotics and delaying the onset of full resistance.Antimicrobial resistance (AMR) is immediate pressing global threat. In 2016, AMR caused 700,000 deaths worldwide, and models predict an increase of up to 10 million deaths per year by 2050, resulting in 100 trillion USD lost in global production5 and classified based on breakpoints as determined by the Clinical and Laboratory Standards Institute (CLSI)6. While this produces reliable, reproducible, quantitative results, this method is also limited by its tedious preparation, high cost, and laboratory requirments5. It is currently impractical to preform broth serial dilutions for multiple antibiotics for several patients without the aid of automated equipment. Other methods for AST may include automated devices, premade 96-well plates, E-test gradient strip diffusion, or agar disk diffusion. While these technologies are logistically simpler than broth dilution, they may be more expensive, bulkier, or require refrigerated agar plates making them unamenable to low resource settings. When none of these methods are available, clinicians may prescribe patients an antibiotic treatment based on infection source or current regional resistance trends8.The gold standard method of AST is broth serial dilution, where solutions of antibiotics diluted two-fold are prepared, spiked with bacteria, and the minimum inhibitory concentration is obtained1. This is especially important for low- and middle-income countries that lack the resources or infrastructure necessary to perform drug susceptibility testing10. It is therefore necessary to develop a low-cost point-of-care diagnostic to accurately predict effective antibiotics for treating a patient based on their individual infection resistance profile. Point-of-care diagnostic devices should be affordable, portable, robust, designed to work in a wide variety of settings, use small sample volumes, and have a quick turnaround time13. Paper microfluidics specifically offer several additional benefits: they are disposable, require no power supply, and are easy to scale for mass manufacturing15. Such a test could provide a global picture of emerging AMR, guide public health and policy, and improve individual patient outcomes.The consensus Review on Antimicrobial Resistance concluded that “the solution to the problem (of AMR) must work for the world and benefit as many people as possible, not one country or one group of countries,” and thus “the solutions should be cost-effective, affordable and support economic development”Bacterial Paper Antibiotic Susceptibly Testing Chip. The Bac-PAC is a paper microfluidic chip capable of giving colored readouts visible to the naked eye corresponding to the susceptibly of a patient-specific bacterial strain. This work improves on our previous publication by Wang and Erickson16 through (1) multiplexing to include three antibiotics while maintaining semi-quantitative readouts, (2) exploration of additional colorimetric dyes that demonstrated better performance with some antibiotics, (3) proof of concept validation with 30 bacterial strains from 12 different species contained in the “Enterobacterales Carbapenem Breakpoint" panel17 , major , and very major  in accordance with CLSIIn designing the Bac-PAC, we sought to maximize categorical agreement and to minimize major and very major discrepancies while also spanning the widest range of antibiotic concentrations possible. Gold standard broth microdilution testing involves adding bacteria to broth containing antibiotics that are diluted two-fold until growth of the bacteria ceases Fig. a. These Prior to testing, dyes and antibitoics were mixed and immobilized on the chip by drying. No color change was seen in the center of the chip implying that the dye stayed well confined in the wells. As mentioned previously, the antibiotics may flow back into the center of the chip, but they do not impact adjacent wells. If antibiotics were influencing adjacent wells, the positive control would disappear, especially in the case of high susceptible samples, and the test would be invalidated. Therefore, since no mixing of antibiotics was observed, the antibiotic configurations can easily be changed based on clinical needs, such as local resistance trends or antibiotic availability.21.Ciprofloxacin, meropenem, and gentamicin two-fold and four-fold dilutions had an average categorical agreement of 79% compared to 77% for six-step dilutions Fig. . CefazolWe compared XTT and PrestoBlue side by side to identify any major differences in accuracies between the two dyes for each antibiotic. Meropenem performed significantly better when paired with XTT compared to PrestoBlue: Meropenem-Presto displayed only a 50% accuracy with 23% major discrepancies compared to 83% accuracy with no major discrepancies for Meropenem-XTT. We suspect this is due to a chemical interaction between meropenem and the resazurin component of PrestoBlue dye. Cefazolin, tobramycin, and ampicillin displayed significantly higher very major discrepancies rates using XTT dye. In all dilution cases, gentamicin displayed similar accuracies between PrestoBlue and XTT but had fewer very major discrepancies using PrestoBlue. Overall, XTT had better accuracy in general but at the expense of higher very major errors rates, which could lead to misprescribing of antibiotic therapies.For clinical use, diagnostic assays are manufactured, transported, and stored for some amount of time prior to use. Therefore, the Bac-PAC was evaluated for storage temperature and shelf-life. The paper chips were prepared as in all previous experiments, dried at ambient air for approximately 10 mins, and placed in heat seal packaging with a single desiccator packet. Half of the chips were stored at room temperature (approximately 20 °C) while the other half were stored in the fridge (approximately 4 °C).Chips stored at room temperature for one month displayed some color change even without bacteria. PrestoBlue appeared to be converted by the highest concentrations of meropenem and gentamicin Fig. a while XChips stored in the fridge at 4 °C fared much better and retained higher accuracies after one month when compared to those at room temperature. In all cases except for meropenem, the choice of dye made little difference in the overall accuracy of the test. With meropenem, however, use of PrestoBlue lead to a very high minor and major discrepancy rate compared to XTT after one month of storage in the fridge Fig. c. This iWhile our results thus far are promising, they still rely on a large, water jacketed, energy intensive standing incubator which is not conducive to the point-of-care. Therefore, we substituted the 400 lb incubator for a 2.5 oz Smart Mug Warmer  and Food and Drug Administration (FDA) Antibiotic Resistance Isolate Bank35 based on Clinical Laboratory Standard Institute’s M100 Performance Standards for Antimicrobial Susceptibility Testing6. Certified Pharmaceutical reference or secondary standards were used for all six antibiotics tested.Gold standard antibiotic susceptible categories were assigned by the CDC/FDA Antibiotic Resistance Isolate BankAntibiotic stock solutions were diluted in 2 mg/mL XTT with 5 μg/mL phenazine methosulfate or pure PrestoBlue Cell Viability dye. The highest working concentration of antibiotic dye solution was diluted twice either 1 to 2, 1 to 4, or 1 to 6 depending on the trial requirements. 3μL of dye-only solution or antibiotic dilution were loaded on to the pre-printed and melted microfluidic chip starting at the 3 o’clock position and continuing from lowest to highest antibiotic concentration moving counterclockwise  divided by the total number of categorizations, once incomplete tests were removed. Percent “major” discrepancies were calculated as the number of false-resistant results  divided by the total number of categorizations, once incomplete tests were removed. Percent “very major” discrepancies were calculated as the number of false-susceptible results  divided by the total number of categorizations, once incomplete tests were removed.Supplementary Figures.Supplementary Video 1.


It was shown that the solution of the boundary value problem of non-stationary mass conductivity allows us to conclude about the duration of the service life of a concrete structure, which will be determined by the processes occurring at the interface: in concrete—mass conductivity, depending on the structural and mechanical characteristics of hydraulic structures, and in the liquid phase—mass transfer, determined by the conditions of interaction at the interface of the indicated phases.This study built theoretical and practical models to evaluate the corrosion resistance of concrete for coastal offshore structures in Vietnam. A mathematical model was developed in the form of a system of nonlinear partial differential equations characterizing the diffusion “free calcium hydroxide” in a solid of a concrete structure. The model describes the process of non-stationary mass conductivity observed in the “concrete structure—marine environment” system under non-uniform arbitrary initial conditions, as well as combined boundary conditions of the second and third kind, taking into account the nonlinear nature of the coefficients of mass conductivity  The South China Sea plays an important role in Vietnam’s history, since the coastline from north to south is about 3260 km. Many important economic centers and defense facilities of the country are located on the coast. The accumulated experience shows that many hydrotechnical reinforced concrete structures, after 5 on 10 years of operation, develop damage caused by corrosion processes occurring in an aggressive marine environment. The rate of corrosion damage is quite high, especially in tidal waters. Thus, the issues of increasing the reliability and durability of the operation of hydrotechnical facilities in the coastal zone of Vietnam are very relevant and are of great economic and social importance for the country [The destruction of reinforced concrete structures occurs due to corrosion processes caused by diffusion (mass transfer) between the concrete components and the ions of aggressive components of the liquid phase ,3,4. RecThis paper considers the basic methods of physical-mathematical modeling that are used to describe the processes of non-stationary mass transfer of “free calcium hydroxide” in concrete structures placed in a liquid environment with a defined flow rate. The boundary value problem of “free calcium hydroxide” mass conductivity in dimensionless variables is obtained. To demonstrate the possibilities of the obtained solution, we will carry out a numerical experiment: in which the fluctuation in the field of dimensionless concentrations SP), as well as silica fume (SF) and mechanically activated low-calcium fuel fly ash (FA) and rice husk ash (RHA)—finely dispersed mineral admixtures the composition of a multicomponent adhesives and having a high pozzolanic activity due to a significant content of amorphous silica [Theoretical model is applied to corrosion resistant concrete (CRC) with a modified structure based on sulfate resistant Portland cement using mainly local materials, suitable for the construction of offshore structures in coastal areas, which can be carried out by compaction and strengthening of the structure of the cement stone due to the combined effect of modifying admixtures (MA), introduced into the concrete mixture, in the form of a water-reducing polycarboxylate superplasticizer  produced by the Tam Diep plant, which is the leading cement manufacturer in Vietnam using the most modern world technologies. The main characteristics of clinker and Portland cement based on it met the requirements of ASTM C150-07 [Sulphate resisting portland cement type CEM I 42.5N CC  conforms to the standard TCVN 10302:2014 [SF) and rice husk ash (RHA) conforms to the standard TCVN 8827:2011 [Active mineral admixtures allow to reduce the consumption of cement, as well as to compact the structure of concrete by reducing the porosity of the cement stone and thereby improving its operational properties, and in addition, to avoid stratification of the concrete mixture when using water-reducing superplasticizers ,15,16. L302:2014  and GOST302:2014 , Vina Pa827:2011 . Their cFA, SF and RHA, shown in Granulometric composition of SS) of the Lo River (Vietnam) was used as a fine aggregate. It is a popular construction sand in Vietnam with good quality and low price. The grain size composition of sand is important for the preparation of concrete mixtures of the required consistency, since it has a significant effect on their workability and the amount of mixing water required for this. The regulatory requirements for the physical and mechanical properties of sand are set out in the Russia and Vietnam standards GOST 8736-2014 [Silica sand (736-2014 . The resCS) with Dmax = 10 mm, which is mined in open pits in Ninh Binh (Vietnam) and whose properties corresponded to the requirements of the standards GOST 8267-93 [As a coarse aggregate, we used crushed stone  from SilkRoad (Vietnam) with a density of 1.1 g/m3 at a temperature of 20 ± 5 °C was used as a plasticizing additive in concrete mixtures, which reduces the water demand of equally mobile concrete mixtures by 30–40% that meets the requirements of GOST 24211-2008 [The superplasticizer SR 5000P  used for the preparation of concrete mixtures complied with the requirements of GOST 23732-2011 [Water .To develop effective methods for protecting concrete from leaching by a marine environment containing a range of different ingredients that have a significant effect on the rate of decomposition of highly basic compounds and the removal of decomposition products into the marine environment, it is necessary to develop mathematical models of unsteady mass conductivity (diffusion in a solid) under non-uniform arbitrary initial conditions and combined boundary conditions of the 2nd and 3rd kind. Particular attention should be paid to taking into account the nonlinearity of the coefficients of mass conductivity and mass transfer.In accordance with the classification of Professor V.M. Moskvin , the simIn this case, it is assumed that the target component, which is free calcium hydroxide in the processes of corrosion of cement concrete, is removed from the surface of a concrete or reinforced concrete structure by a liquid medium as a result of convective mass transfer. If the medium is stationary, then the mass transfer will be characterized by natural convection, and if the surface of the structure is washed with a liquid at a certain speed of its movement, then there is a forced flow of the liquid. In both cases, the mass transfer of the target component will be determined by two processes: mass conductivity from the inner layers to the interface and mass transfer from the interface to the liquid phase ,37,38,39The model of the problem of mass transfer with initial and boundary conditions for an unbounded plate concrete (reinforced concrete) can be schematically illustrated in C0 is the initial concentration of free calcium hydroxide in concrete, in terms of calcium oxide, kg CaO/kg concrete; C is the concentration of free calcium hydroxide in concrete at the moment τ at any point with the coordinate x, in terms of calcium oxide, kg CaO/kg concrete; k is coefficient of mass conductivity in the solid phase (diffusion), m2/s; β is mass transfer coefficient in a liquid medium, m/s; Cp is the equilibrium concentration of the transferred component on the surface of a solid; kg CaO/kg concrete; δ is wall thickness of the structure, m.The problem of mass transfer of calcium hydroxide from a concrete structure into an aqueous substance can be formulated by the following system of Equations (1)–(4):The Equation (1) is the differential equation of non-stationary mass transfer in the body of a reinforced concrete structure. The Equation (2) defines the initial condition of the process: the distribution of calcium hydroxide concentrations at the time instant taken as the initial one. The Equations (3) and (4) expressions define the conditions at the interface. The Equation (3), called the condition of the 2nd kind, also called the “non-penetration condition”, determines the fact that calcium hydroxide does not diffuse into the internal premises of the hydraulic structure located on the left from enclosing concrete (reinforced concrete) construction. The Equation (4) characterizes the interaction of the surface layer of the structure with a liquid medium. This is a condition of the 3rd kind, also called “Newton’s condition”.The use of dimensionless variables allows you to go to the following Equation (5):In this case, the system of Equations (1)–(4), also called the “boundary value problem of non-stationary mass transfer”, is transformed to the from:The purpose of solving this boundary value problem is to find a function process” . The solprocess” ,41.(10)Some results of calculations by Equation (10) are shown in Based on the studied causes and nature of corrosion of offshore hydraulic structures, in order to increase the durability of cement stone of concrete and reinforced concrete structures, experimental studies were carried out in the laboratories of the Civil Engineering Faculty of the Hanoi Mining and Geological University and the Institute of Construction Sciences and Technologies of the Ministry of Construction of Vietnam in accordance with the requirements of the standards ACI 211.4R-08 , developThe experimental results of determining the physical, mechanical, and performance indicators of the developed concretes of the above compositions and, for comparison, the requirements for concrete in accordance with SP 41.13330.2012  are presSiO2 (89.9%) in the silica fume of the mineral sealing additive, which is confirmed by the results of X-ray phase analysis.From the test results given in These results are fully consistent with the results of the analysis of the microstructure of concrete of the developed compositions, obtained using the method of electron microscopy and showing a denser structure in CRC of Mix 3 and 4 compared to Mix 1 and 2 .FA, SF, and RHA), the method of X-ray phase analysis was used to study their influence on the phase composition of the adhesive’s hydration products during the hardening of concrete of Mix 1, 2, 3 and 4.In order to assess the pozzolanic properties of the used mineral admixtures 2—portlandite decreases in concretes of Mix 3 and 4, and at the same time, the intensity of the peaks of calcium hydrosilicate increases. This can be explained by the occurrence of the pozzolanic reaction of SF, RHA, and FA with portlandite, the rate of which increases with the hardening of these concretes, as a result of which the absorption of calcium hydroxide and its transformation into hydrosilicate occurs more intensively than the formation of Ca(OH)2 as a result of hydration of Portland cement clinker minerals. It was found that at the age of 28 days of normal hardening, the highest intensity of CSH peaks and the smallest CH peaks are observed in the concrete of Mix 3 containing silica fume, which can be explained by its high pozzolanic activity.The presented figures show that, in contrast to Mix 1 and 2, the intensity of the peaks of free The results obtained allow us to conclude that mechanically activated ash and silica fume has a positive effect on the formation of low-basic calcium hydrosilicate in the structure of hardening concretes, which will increase their density, strength, and corrosion resistance under operating conditions.Determination of the coefficient of mass conductivity is not limited to purely technological problems associated with the fact that the coefficient of mass conductivity is included in the calculated equations of the ongoing processes, but is of great scientific importance, since allows you to study the mechanism of the process and the influence of various factors on the rate of transfer of matter .To determine the content of calcium hydroxide over the thickness of the concrete structure, an experimental scheme was developed, as shown in The content of calcium hydroxide was determined by thermogravimetric analysis in the central zone of the samples every 25 mm of thickness with a 14-day interval during 70 days of testing. As a result, profiles of calcium hydroxide concentrations were obtained over the thickness of the sample in an aqueous medium .k of calcium hydroxide. The calculation results are shown in Analyzing the concentration profiles of calcium hydroxide over the thickness of concrete samples of different composition, we determined the concentration gradients of calcium hydroxide at the interface and, using Equation (1) and the Matlab and Origin 2018 software, calculated the value of the mass conductivity coefficient The change of mass conductivity coefficient with time is shown in δ = 0.3 m;Thickness of the concrete structure of the hydraulic structure: τ = 56 days.Coefficient of mass conductivity of calcium hydroxide in concrete k according to As an illustration, the following is a specific example of calculating the corrosion time of a concrete structure:m,critFo, equal to one  show that the critical value of the dimensionless concentration of the transferred component, free calcium hydroxide, over the thickness of concrete The results of calculating the corrosion time of concrete structures from the four investigated concrete compositions are shown in τ is included in the exponential function, which is a factor in each term of the Fourier series. Therefore, the solution to the “inverse mass transfer problem” is possible only with the use of the iteration method [To solve the problem of protecting a reinforced concrete structure from the aggressive effects of the marine environment, it is necessary to use the obtained expression to solve the “inverse problem of non-stationary mass transfer” in order to find conditions under which the processes of mass transfer would be carried out with a minimum leaching rate. It is possible to control this process by influencing the structure of the concrete in the structure. Obviously, the time parameter is the Fourier mass transfer criterion. It is also obvious that the time n method .FA in the composition of multicomponent adhesives and SF as an active mineral finely dispersed sealing additive. The research results show that the developed experimental model can be used to solve the inverse problem of unsteady mass conductivity in order to determine the mass conductivity coefficient of calcium hydroxide in a concrete structure. This model can serve as a basis for predicting the service life of the concrete and reinforced concrete structures of hydraulic structures in the marine aquatic environment.From the results of calculations given in (1) Compositions of corrosion resistant concretes have been developed for the construction of underwater parts of offshore hydraulic structures of the coastal zone, the structure of which is modified with active mineral admixtures  and polycarboxylate superplasticizer in the form of water.k and mass transfer β.(2) A mathematical model has been developed in the form of nonlinear partial differential equations characterizing unsteady mass conductivity—diffusion in a solid of a concrete (reinforced concrete) structure of free calcium hydroxide, observed in the system “concrete (reinforced concrete) structure—marine environment” under uneven arbitrary initial conditions, as well as combined boundary conditions of the 2nd and 3rd kind, taking into account the nonlinear nature of the coefficients of mass conductivity (3) It is shown that the solution of the boundary value problem of unsteady mass conductivity allows us to conclude about the durability of the concrete (reinforced concrete) structure, which will be determined by the processes occurring at the interface: in concrete—mass conductivity, depending on the structural and mechanical characteristics of hydraulic structures, and in liquid phase—mass transfer, determined by the conditions of interaction at the interface between these phases. At the same time, the analysis of the liquid phase will make it possible to assess the duration of the serviceability of these structures and, as a result, it becomes possible to design the optimal compositions of corrosion resistant concretes intended for the construction of durable offshore structures, due to their high resistance to corrosion in seawater.


Campylobacter enterocolitis. We conducted a retrospective review of hospitalized patients younger than 18 years diagnosed with Campylobacter enterocolitis from July 2015 to December 2019. This study aimed to investigate antibiotic prescribing practices and the clinical outcomes and to evaluate the factors associated with antibiotic use. A total of 157 patients  were included in this study. Most patients (93.0%) had a fever, and a quarter of the patients complained of bloody diarrhea. The overall antibiotic prescribing rate was 36.7% (57/157), 91.2% of the patients received antibiotics within hospital day 2. The semi-annual antibiotic prescribing rate ranged from 16.7 to 50.0%. There were no increasing or decreasing trends in antibiotic prescribing rates. Cephalosporins were the most prescribed antibiotics for initial antibiotic therapy. Azithromycin use increased significantly during the study period. The independent factors associated with early antibiotic therapy were leukocytosis (adjusted odds ratio (aOR), 3.95; 95% confidence interval (CI), 1.76–9.27), C-reactive protein ≥50 mg/L , and performing abdominal imaging studies . There was no significance in defervescence between the early and no-antibiotic therapy groups (p = 0.232). A careful assessment of the need for antibiotic therapy in patients with acute diarrhea should be conducted to avoid unnecessary use. After identifying the causative pathogens, the appropriateness of antibiotic prescription should be evaluated.Antibiotics are not routinely recommended for patients with  Campylobacter is one of the most common causes of bacterial enterocolitis in humans, particularly children and young adults [Campylobacter is 1 of 4 key global causes of diarrheal diseases [Campylobacter infection every year [Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) account for most human infections [Campylobacter enterocolitis is characterized by fever, diarrhea, and abdominal cramps, and is often accompanied by bloody stools [Campylobacter infection, is self-limited and resolves without specific antimicrobial treatment [g adults ,2,3,4. Tdiseases . Active ery year . Campyloy stools ,8,9,10. reatment .Campylobacter species have inherited resistance to trimethoprim and beta-lactam antibiotics including penicillins and cephalosporins [Campylobacter infections who merit antibiotic therapy [Antibiotics are not routinely recommended for most patients with suspected or proven bacterial enterocolitis ,11,12,13Campylobacter enterocolitis are limited [Campylobacter infections could inform antimicrobial stewardship efforts. This study aimed to investigate antibiotic prescribing practices for pediatric patients diagnosed with Campylobacter enterocolitis and to evaluate the factors associated with antibiotic use and the clinical outcomes.Data on antibiotic prescribing practices in pediatric patients with  limited ,10. UndeCampylobacter at Hallym University Dongtan Sacred Heart Hospital, the Republic of Korea, from July 2015 to December 2019. The inclusion criteria of this study were as follows: (1) patients who were hospitalized due to acute symptoms compatible with infectious enterocolitis such as fever, abdominal pain, diarrhea, or vomiting within seven days of onset, and (2) patients in whom Campylobacter was confirmed by the multiplex polymerase chain reaction (PCR) assay  of stool specimens. The Campylobacter species detectable by the multiplex PCR assay were C. jejuni and C. coli. We excluded patients with chronic medical diseases or Campylobacter co-infection with other organisms from the study.We conducted a retrospective study of hospitalized pediatric patients (younger than 18 years old) with acute enterocolitis caused by Campylobacter enterocolitis. Inappropriate antibiotic therapy was defined as maintaining or initiating antibiotics other than azithromycin after confirming the result.We defined patients who received antibiotic therapy within the second day of hospitalization as the early antibiotic group. Patients who did not receive antibiotic therapy during hospitalization and after discharge were classified as the no-antibiotic group. Referring to the 2017 Infectious Diseases Society of America (IDSA) guidelines , we defiCampylobacter enterocolitis, the type of antibiotics prescribed, and the clinical outcomes of the study patients. The clinical outcome variables were fever defervescence by hospital day and length of hospital stay (LOS). The defervescence day was defined as the hospital day when the last fever occurred. We analyzed the factors associated with early antibiotic therapy and compared clinical outcomes between early and no-antibiotic groups.A review of medical records was performed to collect clinical information. We collected data on demographics, the onset time of fever, and gastrointestinal symptoms at hospital admission. Laboratory data on peripheral blood white blood cell (WBC) counts and C-reactive protein (CRP), the hospital day of stool PCR result reporting, and data on imaging studies, such as abdominal ultrasonography (US) or computer tomography (CT), were collected. We investigated treatments for Campylobacter and antibiotic prescribing rate was evaluated using Spearman’s correlation analysis. Fever defervescence curves according to hospital day between the early and no-antibiotics groups were compared by the log-rank test. Multiple logistic regression analysis was performed to assess the independent factors associated with the clinical decision for early antibiotic therapy, and adjusted odds ratios (aORs) and 95% CIs were calculated. We chose potential predictors using statistically significant variables in the univariable analysis. We tested for multicollinearity with variance inflation factors to control for confounding variables and performed the Hosmer–Lemeshow test for goodness-of-fit. Two-sided p-values of < 0.05 were considered statistically significant. The data were analyzed using Prism 9.4.1 .We used descriptive statistics, including medians, interquartile ranges (IQRs), counts, and rates or proportions with 95% confidence intervals (95% CIs). In comparisons between the two groups, Fisher’s exact test and the Mann–Whitney U test were used for categorical and continuous variables, respectively. The Chi-square test for trend was used to evaluate trends of antibiotic prescribing rates over time. The correlation between positive rate of Campylobacter enterocolitis were eligible for this study. The median monthly number of patients was 2 . The monthly positive PCR rate for Campylobacter ranged from 0% to 38.6% . Campylobacter infection was observed through the years and peaked in the summer season (3 and CRP level of ≥ 50 mg/L were 33.8% (53/157) and 57.3% (90/157), respectively. Among 71 patients who underwent abdominal US or CT, 97.2% (69/71) had bowel wall thickening or dilatation, mesenteric lymphadenopathy, or abnormal fluid collection in the intraabdominal cavity. The median time from admission to stool PCR result reporting was 5 days , and 29.3% (46/157) were confirmed to have Campylobacter infection before discharge . Among 57 patients receiving antibiotic therapy, 91.2% (52/57) were included in the early antibiotic group  and 33.3% (19/57) were confirmed with Campylobacter infection before hospital discharge. Six patients (10.5%) received antibiotics after stool PCR result reporting. Of these, four were confirmed with Campylobacter infection within hospital day 2.During the study period, the overall antibiotics prescribing rate was 36.7% (57/157). The semi-annual antibiotic prescribing rate ranged from 16.7 to 50.0% . There were no increasing or decreasing trends in antibiotic prescribing rates a. There Cephalosporins were the most prescribed antibiotics for initial antibiotic therapy . Twenty-Campylobacter infection.Of 19 patients confirmed with Campylobacter enterocolitis before discharge, eight (42.1%) were treated with azithromycin as empirical or targeted therapy, and antibiotic therapy was discontinued in four (21.1%) after confirming the stool PCR results. However, 36.8% of the patients received inappropriate antibiotic therapy even after confirming p = 0.019) and abdominal imaging studies at admission  were significantly higher in the early antibiotic group than in the no-antibiotic group. In the early antibiotic group, there were fewer patients with bloody diarrhea than in the no-antibiotic group . Compared to the no-antibiotic group, WBC counts  and CRP  values were significantly higher in the early antibiotic group.A comparison of the characteristics between the early and no-antibiotic groups is described in 3), high CRP values (≥50 mg/L), and performing abdominal imaging studies at admission were independent factors associated with early antibiotic therapy.The presence of bloody diarrhea, fever on hospital day 1 or 2, performing abdominal imaging studies at admission, and WBC and CRP values were determined to be potential predictors associated with early antibiotic therapy. In the multiple logistic regression analysis , leukocyp-values > 0.999). There was no statistical difference in defervescence curves between the three groups  vs. no-antibiotic, 97.9 vs. 95.9%; azithromycin vs. no-antibiotic, 100.0 vs. 95.9%; antibiotics other than azithromycin vs. no-antibiotic, 96.1 vs. 95.9% , high CRP values (≥50 mg/L), and performing abdominal imaging studies at admission were independent factors associated with early antibiotic therapy. However, there were no differences in fever defervescence and the duration of hospitalization between patients with early antibiotic therapy and those with no-antibiotic therapy.In our study of 157 patients confirmed with Campylobacter in stool samples ranged from 2.6 to 15.0%. According to data from the sentinel surveillance of acute infectious diarrhea by the Korea Disease Control and Prevention Agency, bacterial pathogens were isolated from 11.5–23.7% of the samples between 2012 and 2016 [Campylobacter was one of the most frequently isolated bacterial pathogens, along with nontyphoidal Salmonella (NTS) and Clostridium perfringens, through the sentinel surveillance of acute infectious diarrhea in Korea from 2015 to 2019 [In this study, the semi-annual positive PCR rate of and 2016 . Campylo to 2019 .Campylobacter infections from enterocolitis caused by other organisms without microbiologic testing. It is not always necessary to determine the causative organism of diarrhea. However, diagnostic tests to determine the cause may be needed for patients at a high risk of severe illness and for whom the identification of pathogens would be important or for public health [Salmonella, Shigella, Campylobacter, Yersinia, Clostridioides difficile, and Shiga toxin producing Escherichia coli (STEC) in people with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis [Campylobacter jejuni enterocolitis in children, aged ≥ 5 years, leukocytosis , high CRP values (≥50 mg/L), and performing abdominal imaging studies were independent factors associated with the use of antibiotics in the early days of hospitalization. In an Australian study, Moffatt et al. [Campylobacter-associated hospitalized patients received antibiotics, either empirically or as targeted therapy, for confirmed campylobacteriosis. Vomiting, electrolyte imbalance, and obtaining blood cultures were included in factors associated with antibiotic treatment in the study.Since bacterial causes of diarrhea may have similar clinical presentations, it is challenging to distinguish c health . The 201f sepsis . In a Taocolitis . Bae et ocolitis  noted tht et al.  reportedSalmonella shedding and the occasional shedding of antibiotic-resistant Campylobacter, and may increase the risk of hemolytic uremic syndrome in patients with STEC infection [Campylobacter and NST was 44.8% and 31.7%, respectively [Salmonella and 54.1% of Campylobacter infections [Campylobacter infection after discharge. However, 36.8% of the prescriptions among patients confirmed with Campylobacter before discharge were inappropriate.Most gastrointestinal infections are self-limited among healthy people. Antibiotics are usually not recommended for patients with suspected or proven bacterial enterocolitis. Unnecessary antibiotic use contributes to antibiotic resistance, increase in prolonged nfection ,17. Antiectively . During fections . In a Kofections . In anotfections . If empiCampylobacter infections in children and adults showed that antibiotic treatment shortened the duration of intestinal symptoms by 1.32 days [Campylobacter and accelerated clinical cures in pediatric Campylobacter enterocolitis [A meta-analysis of 11 randomized controlled trials on the effects of antibiotic treatment on the duration of symptoms caused by .32 days . A prospocolitis . Our stuCampylobacter enterocolitis was confirmed by panel-based multiplex PCR assay. Stool cultures for Campylobacter were not performed in our study patients. Data for antibiotic susceptibility testing were not available. Multiplex PCR assay can simultaneously detect several enteric pathogens and Campylobacter may not be the cause of enterocolitis at present [Campylobacter. Second, the appropriateness of antibiotic prescribing could be evaluated in only a few patients. Despite this, our study provided comprehensive data on antibiotic prescribing practices in pediatric patients suspected of bacterial enterocolitis.Our study had several limitations. First,  present ,25. HoweCampylobacter enterocolitis had severe clinical features, the benefits of antibiotic therapy were not apparent in this study. Even after confirming Campylobacter infections, inappropriate antibiotic use was frequently observed. A careful assessment of the need for empirical or targeted antibiotic treatment in patients with acute diarrhea should be performed to avoid unnecessary antibiotic use. Moreover, after identifying the causative pathogens, the appropriateness of antibiotic prescription should be evaluated.Although some pediatric patients with


Pervious concrete has good water permeability and, if used in construction, it can alleviate the heat island effect. However, its low strength and poor durability are major obstacles to its use. This study shows that nano-reinforced pervious concrete created by incorporating cellulose nanofibrils (CNFs) can improve the physical properties and increase the durability of pervious concrete. CNFs were added to the concrete mix in proportions ranging from 0.05% to 0.2% by weight of binder. The additions were found to alter matrix rheology. The hydration kinetics of matrix with differing CNF contents were compared and analyzed. The experimental results show the addition of CNFs delayed peak heat flow and maximum cumulative heat. The 28 d compressive strength of pervious concrete increased by up to 26.5% and 28 d flexural strength by up to 25.8% with the addition of 0.05–0.2% CNFs. Addition of 0.1% and 0.2% CNFs increased water permeability. Addition of 0.05–0.15% CNFs decreased mass loss by 73.2–83.7% after 150 freeze–thaw cycles, which corresponded to an increase in frost resistance. Denser matrices and stronger interfacial transition zones were observed using scanning electron microscopy when 0.05–0.2% CNFs were added. Pervious concrete alleviates the urban heat island effect, thereby improving the urban environment and reducing the severity of environmental problems caused by concrete. Pervious concrete utilized in urban pavements and highways can allow stormwater to pass easily from the surface to subsurface through the interconnected pores, thus avoiding waterlogging. The collected stormwater is further used for the natural recharge of soil. Meanwhile, large interconnected pores can promote the evaporation of water from underlayers. Nevertheless, ordinary pervious concrete usually has poor mechanical properties and low frost resistance due to its high porosity, which can present problems when the concrete is in an extremely wet or cold environment. Researchers have directed attention to producing pervious concrete with high strength, high durability, and excellent water permeability.Traditional methods to improve the strength and durability of pervious concrete include optimizing aggregate size distribution and modifying the aggregate–paste interfacial transition zone (ITZ). A smaller aggregate size or a lower proportion of aggregates increases the strength of pervious concrete but also significantly decreases permeability . Agar-OzRecent research into the application of nanomaterials has produced promising techniques that improve the mechanical properties and durability of concrete. Nanocellulose, an environmentally friendly and renewable nanomaterial, has been increasingly used in cement-based materials. Nanocellulose originates from plant or tree wastes, providing an environmental alternative admixture for cement-based materials. The main forms of nanocellulose are cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), divided by aspect ratio, crystallinity and so on. They have the advantages of high aspect ratio, high elastic modulus, low density, high specific surface area and good thermomechanical stability, and show great potential in this field. Due to the ability of nanocellulose to absorb water, the rheological properties of fresh cement matrix can be adjusted . Thus, nAs stated above, most research has concentrated on the short-term properties of CNF-reinforced cement-based materials, but studies on their durability are very limited. To the best of our knowledge, there is no literature investigating the effects of CNFs on the properties of pervious concrete. Specifically, CNFs show a rheological property-adjusting capacity and nano-reinforced effect for paste, which may have the potential to improve the bonding between aggregates for pervious concrete. In this study, we prepared samples of a new generation of high-performance pervious concrete by incorporating CNFs at 0%, 0.05%, 0.1%, 0.15% and 0.2% by weight of binder. The effects of CNFs on the mechanical properties, water permeability and frost resistance of pervious concrete were quantified. The rheological properties and heat of hydration of the samples were investigated to identify the matrix-strengthening mechanisms. We analyzed SEM images of the matrix and ITZ in specimens.The binders were ordinary Portland cement , silica fume (SF), and class II fly ash (FA); their chemical composition and physical properties are shown in −1 was related to the stretching vibrations in O–H from hydroxyl groups and the peak at 1590 cm−1 was characterized by the antisymmetric stretching vibrations of COO– from carboxylic salt [The CNFs used in this study were provided by Shengquan Group Co., Ltd., Jinan, China, and the physical and mechanical properties of the CNF are tabulated in lic salt ,15. CNFsτ0) and plastic viscosity (μ), were used to quantify the effect of CNF on the rheological properties of the matrix.τ is shear stress (Pa), γ is shear rate (/s), τ0 is yield stress (Pa), μ is plastic viscosity (Pa·s), and c is the regression coefficient.The rheological properties of matrices (without aggregates) were assessed using a cylindrical rotational rheometer , and test setup is shown in Isothermal calorimetry tests were conducted using a TAM air calorimeter  to determine the effect of CNFs on the early hydration of matrices. The fresh paste sample (without aggregates) was sealed into an ampoule and placed into the calorimetric chamber at a temperature of 20 ± 0.1 °C. As shown in P is porosity (%), W2 is the weight of the specimens dried for 24 h (kg), W1 is the weight of the specimen submerged in water (kg) and measured using a hydrostatic balance, ρw is the density of water (kg/mm3), and sV is the volume of the specimen (mm3).Three specimen cubes with 100 mm sides were prepared for the porosity test. Porosity was calculated by Equation (2).k is the permeability coefficient (mm/s), V1 is the initial liquid volume (mm3), V2 is the final liquid volume (mm3), t2 is the finishing time (s), A is the cross-sectional area of the specimen (mm2), L is the height of the specimen (mm), and H is the water head (mm).The water permeability of pervious concrete was quantified by a constant water head method . The tesCompressive strength and flexural strength were measured according to Chinese National Standard GB/T 50081-2019. The 28 d compressive strength was measured on 50 × 50 × 50 mm cubes; specimens were loaded at a rate of 0.5 MPa/s. Four-point flexural strength was measured using 100 × 100 × 400 mm prisms at 28 d at a loading rate of 0.5 MPa/s.f0 is the initial dynamic elasticity, and fi is the dynamic elasticity after a multiple of 25 cycles.Frost resistance was determined by a rapid freeze and thaw (F–T) cycling test according to Chinese National Standard GB/T 50082-2009. Prisms with dimensions 100 × 100 × 400 mm were subjected to F–T cycling. In this test, the central temperature of a specimen was alternatively lowered from 5 ± 2 °C to −18 ± 2 °C and then raised from −18 ± 2 °C to 5 ± 2 °C. One cycle was completed within a 2–4 h period. Mass loss and dynamic elasticity modulus were calculated at intervals of 25 cycles. As shown in The matrices and interfacial transition zones (ITZ) between matrices and aggregates were observed using scanning electron microscopy (SEM). The fresh fractured specimens were dried to a constant weight at 45 ºC and then sputtered with gold–palladium in a vacuum chamber for testing.Matrix rheology is critical in the paste coating of aggregates, and the thickness of a paste corresponds to its viscosity. A nonuniform coating thickness for aggregates leads to a weak ITZ and deterioration of mechanical properties.R2 > 0.99 indicates that the modified Bingham model fits the rheological behavior well. It was found that a 0.05% CNF addition slightly decreased yield stress and plastic viscosity of the matrix and that yield stress and plastic viscosity increased as the proportion of CNFs increased. The addition of the 0.1%, 0.15% and 0.2% CNFs increased yield stress from 6.85 Pa to 19.50, 28.37 and 38.04 Pa, respectively, corresponding to an increase of 184.7%, 314.2%, and 455.3%, respectively. Plastic viscosity increased by 0 to 69.8% when CNF addition increased from 0.1% to 0.2%. We observed that CNFs had a more significant effect on yield stress than on plastic viscosity.The effect of CNFs on the rheological properties of the matrix is attributed to their hydrophilicity, which are similar to those of a viscosity-modifying agent (VMA). The hydroxyl and carboxylate groups on the surface of cellulose skeletons combine with water molecules to form hydrogen bonding, providing the capacity for water adsorption . MoreoveFTIR spectra showed that the surfaces of CNFs contained hydroxyl and carboxylate groups. The oxygen atoms in hydroxyl and carboxylate groups had unpaired electrons, and a hydrophilic complexation was formed when they reacted with calcium ions, which decreased the rate of formation of hydrated calcium silicate and calcium hydroxide . The incThe porosity of pervious concrete determines the water permeability coefficient that characterizes the concrete infiltration capacity. Total porosity and water permeability coefficients of different specimens are shown in The compressive strength and flexural strength of specimens in all groups are shown in An addition of 0.05%, 0.1%, 0.15% and 0.2% CNFs resulted in respective increases in 28 d compressive strength of 5.9%, 14.6%, 26.5% and 15.7%. At 56 d, the addition of 0.05%, 0.1%, 0.15% and 0.2% CNFs resulted in respective increases in 56 d compressive strength of 23.8, 25.7, 27.4 and 24.9 MPa, corresponding to percentage increases of 9.7%, 18.4%, 26.6% and 14.7% compared to the 21.7 MPa compressive strength of the baseline group. F–T damage is a critical concern in pervious concrete applications that are exposed to freezing, such as stadiums and sidewalks. Higher saturation makes pervious concrete frostbitten due to the network of many (semi-) connected pores, thus decreasing mass and reducing strength.The SEM images of matrices with various CNF additions are shown in Porosity, permeability, strength development and frost resistance of pervious concrete with additions of 0.05%, 0.1%, 0.15% and 0.2% CNFs were investigated. The major conclusions are summarized as follows.1.The effects of the CNF addition on the porosity and permeability of pervious concrete were significant. The addition of 0.1% and 0.15% CNFs increased the permeability coefficient from 9.3 mm/s to 12.4 mm/s and from 9.3 mm/s to 10.5 mm/s, respectively, corresponding to increases of 33.3% and 12.9%. These increases were attributed to the increased mixture stability and homogeneity. This case could be explained by the corresponding optimal variation of plastic viscosity and yield stress of unadulterated matrices.2.Although the addition of 0.05–0.2% CNFs significantly delayed the heat flow peak at 0–24 h, cumulative heat increased until 200 h. The cumulative heat for the 0.05–0.15% CNF additions was greater than that for the 0.2% CNF addition.3.The addition of 0.05–0.2% CNFs increased compressive strength by 9.7–26.6% and flexural strength by 6.5–25.8%; the 0.15% CNF addition showed the maximum increase in both indicators.4.When the CNF addition was 0.05%–0.15%, frost resistance of pervious concrete increased with the addition of CNFs, and mass loss was significantly reduced by 73.2%–83.7%; however, with the 0.2% CNF addition, care should be taken to avoid a significant mass loss close to the 0% CNF addition.5.The SEM results showed that the CNF addition changed the morphology and porosity of the hydration products in the matrices and ITZs. The addition of the 0.05–0.15% CNFs increased hydration products and reduced the number of pores, resulting in denser matrices and stronger ITZs. When increased strengths and frost resistance were also considered, additions of 0.1% and 0.15% CNFs could be regarded as optimal.The overall results prove the effectiveness of CNFs as a reinforced agent for improving the short-term strength and frost resistance of pervious concrete. In the future, experiments on long-term strength, sulfate attack and carbonization will be carried out to further study the effects of CNFs on the durability of pervious concrete. Moreover, the application of CNFs in more types of cement-based materials will be studied.