Parallel Samples Research Articles

PMBA: A Parallel MCMC Bayesian Computing Accelerator

Bayesian computing, including sampling probability distributions, learning graphic model, and Bayesian reasoning, is a powerful class of machine learning algorithms with such wide applications as biologic computing, financial analysis, natural language processing, autonomous driving, and robotics. The central pattern of Bayesian computing is the Markov Chain Monte Carlo (MCMC) computing, which is compute-intensive and lacks explicit parallelism. In this work, we propose a parallel MCMC Bayesian computing accelerator (PMBA) architecture. Designed as a probabilistic computing platform with native support for efficient single-chain parallel Metropolis-Hastings based MCMC sampling, PMBA boosts the performance of probabilistic programs with a massive-parallelism microarchitecture. PMBA is equipped with on-chip random number generators as the built-in source of randomness. The sampling units of PMBA are designed for parallel random sampling through a customized SIMD pipeline supporting data synchronization every iteration. A respective computing framework supporting automatic parallelization and mapping of probabilistic programs is also developed. Evaluation results demonstrate that PMBA enables a 17-21 folds speedup over a TITAN X GPU on MCMC sampling workload. On probabilistic benchmarks, PMBA outperforms prior best solutions by factor of 3.6 to 10.3. An exemplar based visual category learning algorithm is implemented on PMBA to demonstrate its efficiency and effectiveness for complex statistical learning problems.

Ising spin configurations with the deep learning method

In this work, we explore the statistical system's configuration generation with generative models from Deep Learning to go beyond conventional Monte Carlo methods. Specifically, we devise a conditional generative adversarial network (cGAN) for the Ising system spin configuration generation, and we demonstrate it's working outside the training range of temperature for the ensemble of configurations. Being different from the original GAN design, we add a further recognizer network for the constraint on the conditional parameters (in our case temperature) and also provide a diversity benefit for the generative model. We showed that the newly proposed cGAN here can learn the distribution of the Ising model for different temperatures, which can generate spin configuration efficiently with correct (within a probability distribution) temperature estimation for the microscopic configurations. Moreover, without information about criticality provided inside the training data set, it is also shown that the developed cGAN can generate Ising spin configurations around the phase transition point with the order parameter (mean magnetization) reasonably well-match to the conventional MCMC simulation but with parallel sampling advantage. We also compared typical spin configurations from cGAN with specified conditional temperature to be the critical temperature with samples simulated by MCMC, which visibly is not distinguishable. This thus can possibly help to avoid critical slowing-down as shown in the traditional Monte Carlo method.

Species differences in phenobarbital-mediated UGT gene induction in rat and human liver microtissues.

Species differences in hepatic metabolism of thyroxine (T4) by uridine diphosphate glucuronosyl transferase (UGT) and susceptibility to thyroid hormone imbalance could underlie differences in thyroid carcinogenesis caused by hepatic enzyme inducers in rats and humans. To investigate this hypothesis we examined profiles of hepatic UGT induction by the prototypical CAR activator phenobarbital (PB) in rat and human liver 3D microtissues. The rationale for this approach was that 3D microtissues would generate data more relevant to humans. Rat and human liver 3D microtissues were exposed to PB over a range of concentrations (500 u M - 2000 u M) and times (24-96 hr). Microarray and proteomics analyses were performed on parallel samples to generate integrated differentially expressed gene (DEG) datasets. Bioinformatics analysis of DEG data, including CAR response element (CRE) sequence analysis of UGT promoters, was used to assess species differences in UGT induction relative to CAR-mediated transactivation potential. A higher proportion of human UGT promoters were found to contain consensus CREs compared to the rat homologs. UGTs 1a6, 2b17 and 2b37 were upregulated by PB in rat liver 3D microtissues, but unaltered in human liver 3D microtissues. By contrast, human UGTs 1A8, 1A10 and 2B10 showed higher levels of induction (RNA and /or protein) compared to the rat homologs. There was general concordance between the presence of CREs and the induction of UGT RNA. As UGT1A and 2B isoforms metabolise T4, these results suggest that differences in UGT induction could contribute to differential susceptibility to CAR-mediated thyroid carcinogenesis in rats and humans.

Algorithm for replica redistribution in an implementation of the population annealing method on a hybrid supercomputer architecture

The population annealing method is a promising approach for large-scale simulations because it is potentially scalable on any parallel architecture. We present an implementation of the algorithm on a hybrid program architecture combining CUDA and MPI. The problem is to keep all general-purpose graphics processing unit devices as busy as possible by efficiently redistributing replicas. We provide details of testing on hardware based the Intel Skylake/Nvidia V100 running more than two million replicas of the Ising model sample in parallel. The results are quite encouraging because the acceleration grows toward the perfect line as the complexity of the simulated system increases.

Presence of Infection by Mycobacterium avium subsp. paratuberculosis in the Blood of Patients with Crohn's Disease and Control Subjects Shown by Multiple Laboratory Culture and Antibody Methods.

Mycobacterium avium subspecies paratuberculosis (MAP) has long been suspected to be involved in the etiology of Crohn’s disease (CD). An obligate intracellular pathogen, MAP persists and influences host macrophages. The primary goals of this study were to test new rapid culture methods for MAP in human subjects and to assess the degree of viable culturable MAP bacteremia in CD patients compared to controls. A secondary goal was to compare the efficacy of three culture methods plus a phage assay and four antibody assays performed in separate laboratories, to detect MAP from the parallel samples. Culture and serological MAP testing was performed blind on whole blood samples obtained from 201 subjects including 61 CD patients (two of the patients with CD had concurrent ulcerative colitis (UC)) and 140 non-CD controls (14 patients in this group had UC only). Viable MAP bacteremia was detected in a significant number of study subjects across all groups. This included Pozzato culture (124/201 or 62% of all subjects, 35/61 or 57% of CD patients), Phage assay (113/201 or 56% of all subjects, 28/61 or 46% of CD patients), TiKa culture (64/201 or 32% of all subjects, 22/61 or 36% of CD patients) and MGIT culture (36/201 or 18% of all subjects, 15/61 or 25% of CD patients). A link between MAP detection and CD was observed with MGIT culture and one of the antibody methods (Hsp65) confirming previous studies. Other detection methods showed no association between any of the groups tested. Nine subjects with a positive Phage assay (4/9) or MAP culture (5/9) were again positive with the Phage assay one year later. This study highlights viable MAP bacteremia is widespread in the study population including CD patients, those with other autoimmune conditions and asymptomatic healthy subjects.

Automated Sample Multiplexing by using Combined Precursor Isotopic Labeling and Isobaric Tagging (cPILOT).

We have introduced a high throughput quantitative proteomics workflow, combined precursor isotopic labeling and isobaric tagging (cPILOT) capable of multiplexing up to 22 or 24 samples with tandem mass tags or isobaric N,N-dimethyl leucine isobaric tags, respectively, in a single experiment. This enhanced sample multiplexing considerably reduces mass spectrometry acquisition times and increases the utility of the expensive commercial isobaric reagents. However, the manual process of sample handling and pipetting steps in the strategy can be labor intensive, time consuming, and introduce sample loss and quantitative error. These limitations can be overcome through the incorporation of automation. Here we transferred the manual cPILOT protocol to an automated liquid handling device that can prepare large sample numbers (i.e., 96 samples) in parallel. Overall, automation increases feasibility and reproducibility of cPILOT and allows for broad usage by other researchers with comparable automation devices.

HIV-2 Drug Resistance Genotyping from Dried Blood Spots.

The treatment of HIV-2 in resource-limited settings (RLS) is complicated by the limited availability of HIV-2-active antiretroviral drugs and inadequate access to HIV-2 viral load and drug resistance testing. Dried blood spots (DBS)-based drug resistance testing, widely studied for HIV-1, has not been reported for HIV-2 and could present an opportunity to improve care for HIV-2-infected individuals. We selected 150 DBS specimens from ongoing studies of antiretroviral therapy (ART) for HIV-2 infection in Senegal and subjected them to genotypic drug resistance testing. Total nucleic acid was extracted from DBS, reverse transcribed, PCR amplified, and analyzed by population-based Sanger sequencing, and major drug resistance-associated mutations (RAM) were identified. Parallel samples from plasma and peripheral blood mononuclear cells (PBMC) were also genotyped. We obtained 58 protease/reverse transcriptase genotypes. Plasma viral load was significantly correlated with genotyping success (P < 0.001); DBS samples with corresponding plasma viral load >250 copies/ml had a success rate of 86.8%. In paired DBS-plasma genotypes, 83.8% of RAM found in plasma were also found in DBS, and replicate DBS genotyping revealed that a single test detected 86.7% of known RAM. These findings demonstrate that DBS-based genotypic drug resistance testing for HIV-2 is feasible and can be deployed in RLS with limited infrastructure.

Development and validation of an intra-calibration procedure for MiniDISCs measuring ultrafine particles in multi-spatial indoor environments

Since the real exposure to indoor ultrafine particles depends on temporal and spatial variation of aerosol concentration, particles dynamic behavior becomes relevant in studying indoor pollution. With this aim, the characterization of Ultrafine Particles (UFPs) variability within different environments (multi-spatial indoor environments) can be regarded as a specific tool in assessing the human exposure. In the case of urban indoor environments, instruments able to measure UFPs at high time resolution with high sensitivity are needed, lightweight and silent. For this purpose, personal monitors unipolar diffusion charging based could be used for their ease of use. Among them, Miniature DIffusion Size Classifier (MiniDISC), a small, silent and wearable analyzer measures particle number concentration, particle modal size and lung deposited surface area of nanoparticles at high time resolution, for dynamic or static use. Nevertheless, the typical ±30% accuracy specified by the manufacturer does not make this sensor reliable enough to measure gradients of urban doses of UFPs occurring in multi-spatial indoor environments.The presented work aims at improving the performances of MiniDISCs for their use in simultaneous measurement of urban UFPs by a multiple set-up, such as in indoor environments inside a building.For this purpose, a new intra-calibration procedure has been developed among MiniDISCs, named Best Intra-calibration (BIC), which corrects data of electrical signals of two or more instruments to those of one selected as reference. Compared to a linear regression analysis for PNC of UFPs, BIC procedure has two main advantages. First, it makes it possible to improve simultaneously the precision of particle number concentration (PNC) and particle modal size (PMS). Secondly, it allows multiple instruments to operate as a fleet, such as a spatial delocalization of an instrument in multiple environments.The procedure was tested in realistic environmental conditions, evaluating indoor PNC and PMS of UFPs by both parallel samplings and multi-spatial samplings. Three types of monitoring campaigns were carried out: inter-comparisons between PNC of UFPs from three MiniDISCs and one Condensation Particle Counter; intra-comparisons between PNC and PMS of UFPs from three MiniDISCs; urban monitoring in-field campaign of UFPs with three MiniDISCs in an indoor workplace, a physic laboratory, in the next hallway and outside. The latter campaign aimed at evaluating how UFPs are influenced by the interaction among different environments inside the building and by the work activity. For these purposes, the dynamical behavior and the ratios Indoor to Outdoor were investigated, in addition to a novel ratio Indoor to Hallway. The BIC procedure allows increasing the precision measured by the weighted coefficients of variation CVs of about 7 times. The results support the novel Intra-calibration procedure to improve the intra variability of MiniDISCs in parallel sampling, making them attractive for measuring UFPs by both the metrics PNC and PMS in multi-spatial indoor environments.

Asymptomatic bacteriuria

Introduction: Asymptomatic bacteriuria (ASB) is a condition characterised by significant infection in urine. Its association with diabetes mellitus is strongly suggested. However, the exact prevalence has been controversial. Objectives: The study was undertaken with the aim of evaluating the prevalence and aetiology of asymptomatic bacteriuria in diabetics as well as non-diabetics. Materials and Methods: A total of 460 patients were included in the study with 230 diabetics and 230 non-diabetics. Midstream clean catch urine samples were collected alongwith parallel blood samples for estimating the glycosylated haemoglobin levels. Results: Of the total 460 subjects, 78 (17.0%) had ASB with 56 in diabetics and 22 in non-diabetics, depicting a higher rate of ASB in diabetes mellitus. Majority of the patients who had ASB were aged more than 60 years, irrespective of whether in the diabetic or non-diabetic category. Also, there was a significant difference in the type of infective organism in urine from diabetic patients as compared to the non-diabetic patients. Conclusion: A higher prevalence rate of ASB was observed in diabetic patients as compared to non-diabetics. Furthermore, the newer infecting organisms that are more common in patients with diabetes mellitus was highlighted in the study. Keywords: Asymptomatic bacteriuria, Urine, Diabetes, Glycosylated haemoglobin

A Novel Restricted Boltzmann Machine Training Algorithm With Dynamic Tempering Chains

Restricted Boltzmann machines (RBMs) are commonly used as pre-training methods for deep learning models. Contrastive divergence (CD) and parallel tempering (PT) are traditional training algorithms of RBMs. However, these two algorithms have shortcomings in processing high-dimensional and complex data. In particular, the number of temperature chains in PT has a significant impact on the training effect, and the PT algorithm cannot fully utilize parallel sampling from multiple temperature chains for the divergence of the algorithm. The training can quickly converge with fewer temperature chains, but this impacts the accuracy. More temperature chains can help PT achieve higher accuracy in theory, but severe divergence at the beginning of the training may ruin the training result. To exploit fully the advantages of PT and improve the ability of RBMs to process high-dimensional and complex models, this article proposes dynamic tempering chains (DTC). By dynamically changing the number of temperature chains during the training process, DTC starts training with fewer temperature chains and gradually increase the number of temperature chains with training going on, and finally get an accurate RBM. And one-step reconstruction error is proposed to measure the convergence, which can decrease the influence of the dynamic training strategy on reconstruction error. Experiments on MNIST, MNORB, Cifar 10, and Cifar 100 indicate that, compared with PT, the classification accuracy of DTC algorithm improved by up to 8&#x0025;. DTC quickly converges in the early stage of training because of few exchanges among temperature chains and produces higher accuracy at the end for the global optimum model learned by more temperature chains, especially when learning high-dimensional and complex data. This proves that the DTC algorithm effectively utilizes parallel sampling of multiple temperature chains, overcomes divergence challenges, and further improves the training effect of the RBM.

Effects of specimen size and loading conditions on the fracture behaviour of asphalt concretes in the SCB test

The semi-circular bending (SCB) test has gained popularity for cracking evaluation of asphalt concrete due to its simplicity in the test setup and sample preparation. The current standards for the SCB test, such as EN 12697-44:2010, AASHTO TP 105-13, ASTM D8044-16, and ASSHTO TP 124-18, utilise 150 mm as the standard diameter for test samples. Recently, the 100 mm diameter was investigated and its applicability for use in the SCB test was confirmed. However, investigation of factors affecting the fracture behaviour of 100 mm diameter samples, such as loading rate, temperature, and aggregate size, is still limited. As yet, no comparison of the SCB fracture performance of 100 mm diameter and 150 mm diameter samples (e.g. fracture toughness, fracture energy, cracking indexes) is available for the nominal maximum aggregate size (NMAS) of 10 mm or larger. Furthermore, conversion of results from the two diameters is not yet available. For applications of the 100 mm samples in parallel with the 150 mm samples, comparisons and conversion of the fracture properties obtained from the two sample sizes are significant. This study was performed to fulfil that purpose. Both SCB sample diameters were prepared with three different thicknesses of 30, 40 and 50 mm, using different NMAS of 10, 14 and 19 mm. The SCB samples were tested at four different loading rates of 0.5 mm/min, 1 mm/min, 5 mm/min and 10 mm/min, and at two temperatures of 25 °C and 10 °C. The study investigated fracture properties including fracture toughness, fracture energy, and cracking indexes such as the flexibility index and the cracking resistance index. The results showed that the fracture toughness for the two diameters was similar, while the fracture energy obtained from the 100 mm samples was roughly 21% less than that achieved from the 150 mm samples. The cracking resistance index results obtained from the 150 mm samples were approximately 8% higher than those obtained from the 100 mm samples. The flexibility index from both diameters showed low correlation. The overall result suggested that the SCB test with 100 mm samples can be used to evaluate the fracture behaviour of asphalt mixtures with NMAS up to 19 mm, and the fracture properties obtained from the two different sample sizes are convertible.

Prediction of Mechanical Performance of Acetylated MDF at Different Humid Conditions

Change of relative humidity (RH) in surrounding environment can greatly affect the physical and mechanical properties of wood-based panels. Commercially produced acetylated medium density fiberboard (MDF), Medite Tricoya®, was used in this study to predict strength and stiffness under varying humid conditions by separating samples in parallel (//) and perpendicular (⊥) to the sanding directions. Thickness swelling, static moduli of elasticity (MOEstat) and rupture (MORstat), and internal bond (IB) strength were measured at three different humid conditions, i.e., dry (35% RH), standard (65% RH) and wet (85% RH). Internal bond (IB) strength was also measured after accelerated aging test. A resonance method was used to determine dynamic modulus of elasticity (MOEdyn) at the aforementioned humid conditions. Linear regression and finite element (FE) analyses were used to predict the MDF’s static bending behavior. Results showed that dimensional stability, MOEstat, MORstat and IB strength decreased significantly with an increase in RH. No reduction of IB strength was observed after 426 h of accelerated aging test. A multiple regression model was established using MOEdyn and RH values to predict MOEstat and MORstat. In both directions (// and ⊥), highly significant relationships were observed. The predicted and the measured values of MOEstat and MORstat were satisfactorily related to each other, which indicated that the developed model can be effectively used for evaluating the strength and stiffness of Medite Tricoya® MDF samples at any humid condition. Percent errors of two different simulation techniques (standard and extended FE method) showed highly efficient way of simulating the MDF structures with low fidelity.

A Long-Read Sequencing Approach for Direct Haplotype Phasing in Clinical Settings.

The reconstruction of individual haplotypes can facilitate the interpretation of disease risks; however, high costs and technical challenges still hinder their assessment in clinical settings. Second-generation sequencing is the gold standard for variant discovery but, due to the production of short reads covering small genomic regions, allows only indirect haplotyping based on statistical methods. In contrast, third-generation methods such as the nanopore sequencing platform developed by Oxford Nanopore Technologies (ONT) generate long reads that can be used for direct haplotyping, with fewer drawbacks. However, robust standards for variant phasing in ONT-based target resequencing efforts are not yet available. In this study, we presented a streamlined proof-of-concept workflow for variant calling and phasing based on ONT data in a clinically relevant 12-kb region of the APOE locus, a hotspot for variants and haplotypes associated with aging-related diseases and longevity. Starting with sequencing data from simple amplicons of the target locus, we demonstrated that ONT data allow for reliable single-nucleotide variant (SNV) calling and phasing from as little as 60 reads, although the recognition of indels is less efficient. Even so, we identified the best combination of ONT read sets (600) and software (BWA/Minimap2 and HapCUT2) that enables full haplotype reconstruction when both SNVs and indels have been identified previously using a highly-accurate sequencing platform. In conclusion, we established a rapid and inexpensive workflow for variant phasing based on ONT long reads. This allowed for the analysis of multiple samples in parallel and can easily be implemented in routine clinical practice, including diagnostic testing.

Study on Microstructure Differences of Coal Samples before and after Loading

The microscopic pore structure of coal affects the content of adsorbed gas. The microstructure of coal sample before and after loading is different, which will affect the adsorption and permeability of coal seam gas. In order to study this difference, the authors carried out mercury intrusion experiments on coal containing different coal samples and used nondestructive nuclear magnetic resonance (NMR) techniques, scanning electron microscopy, and transmission electron microscopy, to study the microstructure of coal samples before and after loading. The experimental results show that the pores of coal samples are mainly micropores and small pores, and the mesopores and macropores are relatively few. The T2 spectrum area of the coal sample is significantly increased after loading, and the parallel-layer coal samples’ T2 spectrum area is 46735, which is 9112 more than the vertical layer coal samples. The T2 spectrum of the vertical coalbed of saturated water samples shows a three-peak shape, the peak of the T2 spectrum is 12692, and the parallel bedding shows a bimodal morphology. The peak area of the T2 spectrum is 11277. The permeability of the parallel bedding coal sample is good, and the coal sample exhibits anisotropic properties. The pores and cracks of the coal samples increased after loading, and the localized area of the coal sample collapsed and formed a fracture zone, which was not conducive to the occurrence of coal seam gas. Further explanation of the changes in the permeability of the coal sample before and after loading will affect the gas storage and transportation.

Profiling Glycoproteins on Functionalized Reverse Phase Protein Array.

Reverse phase protein array (RPPA), a high-throughput, parallel immunoassay in a dot-blot format, is a powerful tool to quantitatively profile protein expression in multiple samples simultaneously using small amounts of material. Despite its success, analysis of post-translationally modified (PTM) proteins has been limited in RPPA assays, primarily due to relatively low availability of antibodies specific to proteins of PTMs, e.g., glycosylation. Moreover, the high matrix complexity, with tens of thousands of proteins in cell lysates or tissue extracts and the low abundance of proteins with PTMs, makes it extremely challenging to detect these proteins with PTMs. Therefore, there is an urgent need to fill this gap, which would greatly contribute to the analysis of a specific PTM by RPPA. In this chapter, we introduce a novel RPPA platform, termed polymer-based reverse phase glycoprotein array (polyGPA), to measure the variation of glycosylation patterns on a three-dimensionally functionalized RPPA. Without the need of specific antibody towards glycosylation, polyGPA represents a highly sensitive strategy to analyze protein glycosylation in multiple complex biological samples in parallel.

Element transfer by a vapor-gas stream from sulfide mine tailings: from field and laboratory evidence to thermodynamic modeling.

Condensates of vapor-gas streams were collected during field and laboratory experiments for the determination of the volatility of chemical elements in sulfide tailings under ambient conditions. The object of research was the Ursk waste heaps (Kemerovo region, Russia). Field experiments were performed on the top of the heap and in neighboring territories; the elements' concentrations in condensates from the top exceed the background values in 2-3 orders of magnitude. To obtain condensates in the laboratory, the waste material was heated to 60 °С. Laboratory condensate-contended high concentrations Ca, Mg, but Fe, Cd, Mo, Sn, Zr, and W were lower by more than 2 orders of magnitude. Also, chemical elements such as Au, Zr, Cs, U, and Tl were determined in the laboratory condensates at elevated temperatures. Also, solid samples were leached with water at the laboratory. A high positive correlation of condensate compositions with compositions of water extracts obtained from parallel samples was established. The most mobile elements transferred in the steam-gas phase are alkaline (Li, Cs, Na, K), alkaline earth (Ca, Sr), chalcophile metals (Hg, Zn, Cu), and metalloids (As, Sb, Se). The numerical experiment of metal transfer forms using thermodynamic modeling methods has been performed, including those with organic ligands.

Performance Parameters of Inductively Coupled Plasma Optical Emission Spectrometry and Graphite Furnace Atomic Absorption Spectrometry Techniques for Pd and Pt Determination in Automotive Catalysts.

Palladium (Pd) and platinum (Pt) are extensively used as catalysts in the petrochemical and automotive industries, and due to high demand for them on the market, their recycling from spent supported catalysts is clearly needed. To assess the content of Pd and Pt in catalysts in order to establish their commercial value or to evaluate the recovery efficiency of technologies used for recycling, reliable analytical methods for determination of these elements are required. Spectrometric methods, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (GFAAS) are powerful tools that can be employed for the determination of Pd and Pt in various sample matrices. However, these methods allow only the injection of liquid samples. In this regard, the digestion of solid sample by microwave-assisted acid extraction procedures at high pressures and temperatures is often used. In this study, a microwave acid digestion method was optimized for the extraction of Pd and Pt from spent catalysts, using a four-step program, at a maximum 200 °C. The resulting solutions were analyzed using ICP-OES, at two different wavelengths for each metal (Pd at 340.458 and 363.470 nm, and Pt at 265.945 and 214.423 nm, respectively) and using GFAAS (Pd at 247.64 nm, Pt at 265.94 nm). Five types of spent catalyst were analyzed and the standard deviations of repeatability for five parallel samples were less than predicted relative standard deviations (PRSD%) calculated using Horvitz’s equation for all the analyzed samples.

Method for phosphate oxygen isotopes analysis in water based on in situ enrichment, elution, and purification

The phosphate oxygen isotope (δ18OP) ratio has been proven to be an effective tool to trace the sources and biogeochemical cycles of phosphorus (P) in aquatic ecosystems. However, the enrichment of phosphate (PO4) and the removal of impurities are quite complex and easy to cause PO4 loss in current δ18OP analytical methods. Moreover, the δ18OP value obtained by the commonly-used instantaneous sampling method is more of the instantaneous information of P, which is accidental or uncertain for accurate identification of the P source. In this study, a new method of in situ enrichment, elution, and purification of PO4 (ISEEP) was developed for δ18OP analysis in waters. This method utilized a PO4 binding phase (Zr-Oxide gel) to selectively in situ adsorb PO4 in water and exhibited an adsorption capacity per unit area of up to 789.3 μg P/cm2. The PO4 on the gel was eluted easily with a 1 M NaOH solution. More than 99.7% of the common anions, cations, and dissolved organic matter (DOM), as well as more than 90% of the trace elements were removed synchronously after adsorption and elution of PO4. The recovery rate of PO4 in the whole procedure was as high as 92.8%. The XRD and SEM examinations showed that the ISEEP can obtain high-purity Ag3PO4 solid for the δ18OP measurement. The reliability of the ISEEP method is confirmed by the measured δ18OP value and standard deviation of parallel samples from different types of natural waters obtained by both the ISEEP and the current popular McLaughlin (2004) method. It provides a good prospect of this new method for tracing the P sources and their biogeochemical cycling in aquatic ecosystems.

Mapping of Hydrogen Fuel Quality in Europe

As part of FCH-JU funded HyCoRA project running from 2014 to 2017, 28 gaseous and 13 particulate samples were collected from hydrogen refueling stations in Europe. Samples were collected with commercial sampling instruments and analysis performed in compliance with prevailing fuel quality standards. Sampling was conducted with focus on diversity in feedstock as well as commissioning date of the HRS. Results indicate that the strategy for sampling was good. No evidence of impurity cross-over was observed. Parallel samples collected indicate some variation in analytical results. It was however found that fuel quality was generally good. Fourteen analytical results were in violation with the fuel tolerance limits. Therefore, eight or 29 % of the samples were in violation with the fuel quality requirements.Violation of the tolerance for impurities in fuel was observed in some samples. Nitrogen, oxygen and organics were the predominant impurities quantified. Particulate impurities were found to be within fuel quality specifications. No correlation between fuel quality and hydrogen feedstock or HRS commissioning date was found. Nitrogen to oxygen ratios gave no indication of samples being contaminated by air. A comparison of analytical results between two different laboratories were conducted. Some difference in analytical results were observed.

Enhancement of mechanical properties and thermoelectric performance of spark plasma sintered P-type Bismuth Telluride by powder surface oxide reduction

In the present investigation, key mechanical design parameters and the thermoelectric performance of powder ball milled spark plasma sintered P-type Bi0·4Sb1·6Te3 material was determined. In particular, the effect of the powder preparation technique on the powder surface oxide layer as well as both the mechanical and thermoelectric properties were determined. All measurements were performed on identically prepared sintered samples in both parallel and perpendicular to the applied sintering pressure. The mechanical properties determined included relative density, uniaxial tensile strength, coefficient of thermal expansion, Young’s modulus, Poisson’s ratio, and shear modulus. The thermoelectric properties measured included the Seebeck coefficient, electrical resistivity, and thermal conductivity. A mechanically agitated reduction facility built in-house was used to reduce the powder surface oxide at 380 °C for 24 h using dry 5% H2 95% Ar. To separate between the annealing and the reduction effects, the P-type (Bi, Sb)2Te3 powder was annealed using highly purified Ar at the same temperature and time as the reduction process. The oxygen content in the sintered P-type samples was then measured using the inert gas fusion technique. The oxygen content was found to be decreased by 35 wt% after 24 h of reduction but did not change significantly after annealing with Ar only relative to the dried powders. The reduction of the surface oxides increased the relative density of the sintered parts from 97.1% to 99.2%. Consequently, the characteristic uniaxial tensile strength increased from 13.9 MPa to 26.3 MPa and from 16.3 MPa to 30.6 MPa in the parallel and the perpendicular directions to the sintering pressure, respectively, for the sintered bodies from the reduced powder. Both the Young’s modulus and the shear modulus increased from 44.3 GPa to 48.7 GPa and 17.8 GPa–19.5 GPa in the parallel direction, respectively, after the reduction treatment and sintering. The figure of merit, ZT, increased from 0.35 to 0.80 and from 0.42 to 1.13 at room temperature (25 °C) in the parallel and the perpendicular directions, respectively, after the surface oxide reduction treatment.