2nd Step Research Articles

Coinage metals doped 1T′ WS2 as efficient bifunctional electrocatalyst towards ORR and HER: A first principles study

The electrocatalytic activities of Cu, Ag and Au doped 1T′ WS2 as electrocatalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in acidic medium are explored by means of first principles calculations. The stability of these doped systems are inspected in terms of formation energy and charge transfer analysis upon doping. Highest amount of charge transfer towards the dopant is observed for systems with lowest formation energy. For all the doped systems, charge is transferred to the dopant that substitutes the anionic S atom validating the doping scheme and stability of the doped systems. ORR proceeds only via the energetically efficient four electron pathway on Cu doped 1T′ WS2 with a monotonically exothermic free energy profile. In the case of Ag and Au doped structures, ORR occurs competitively via both two and four electron pathways due to the marginal free energy difference in the 2nd protonation step between these two pathways and produces both H2O or H2O2 competitively as the end product. Study of the effect of electrode potential variation on the free energy profiles reveals the overpotential for ORR on Cu, Ag and Au doped 1T′ WS2 to be 0.85 V, 0.80 V and 0.66 V respectively via the four electron pathway. Proneness of Cu doped 1T′ WS2 towards only the four electron pathway and low overpotential for ORR makes it the promising cathode electrocatalyst for ORR among the considered systems. Further study of the HER activity of Cu, Ag and Au doped 1T′ WS2 reveals the Gibbs free energy of H+ ion adsorption on Cu doped 1T′ WS2, Ag doped 1T′ WS2 and Au doped 1T′ WS2 to be −0.14 eV, −0.17 eV and 0.18 eV respectively indicating high efficiency of those system towards HER in acidic medium.

End-to-end neural speaker diarization with an iterative adaptive attractor estimation

End-to-end neural diarization (EEND) which has the capability to directly output speaker diarization results and handle overlapping speech has attracted more and more attention due to its promising performance. Although existing EEND-based methods often outperform clustering-based methods, they cannot generalize well to unseen test sets because fixed attractors are often utilized to estimate speech activities of each speaker. An iterative adaptive attractor estimation (IAAE) network was proposed to refine diarization results, in which the self-attentive EEND (SA-EEND) was implemented to initialize diarization results and frame-wise embeddings. There are two main parts in the proposed IAAE network: an attention-based pooling was designed to obtain a rough estimation of the attractors based on the diarization results of the previous iteration, and an adaptive attractor was then calculated by using transformer decoder blocks. A unified training framework was proposed to further improve the diarization performance, making the embeddings more discriminable based on the well separated attractors. We evaluated the proposed method on both the simulated mixtures and the real CALLHOME dataset using the diarization error rate (DER). Our proposed method provides relative reductions in DER by up to 44.8% on simulated 2-speaker mixtures and 23.6% on the CALLHOME dataset over the baseline SA-EEND at the 2nd iteration step. We also demonstrated that with an increasing number of refinement steps applied, the DER on the CALLHOME dataset could be further reduced to 7.36%, achieving the state-of-the-art diarization results when compared with other methods.

Transition from upright to greater forward lean posture predicts faster acceleration during the run-to-sprint transition.

BackgroundForward body lean and greater horizontal ground reaction force have been associated with being able to accelerate during running. However, kinematic features which may predict acceleration during the run-to-sprint transition have not been determined. The purpose of this study was to determine which kinematic changes occur in recreationally active adults and which kinematic features may predict greater acceleration during the run-to-sprint transition. MethodsForty-seven healthy adults completed straight line running along a 30 m track by running in at ∼4 m.s-1. A minimum of 20 trials were completed, with 25 % triggering a light to signal the participant to accelerate as fast as possible. Step characteristics (velocity, length, duration, cadence) and kinematics (neck, trunk, hip, knee and ankle angles and excursions) were determined using a radar gun and inertial measurement units, respectively. ANOVA was used to determine the step-to-step differences and a multiple linear regression was used to determine the relationship between kinematics and acceleration. ResultsThere was an initial increase in trunk flexion angle during early acceleration (p < 0.001) with knee joint excursion significantly lower (p < 0.001) during loading and propulsion compared to the run-in steps. Greater acceleration was predicted using a stepwise linear regression by five variables including less neck flexion excursion and trunk flexion angle during swing of the 1st step, greater trunk flexion angle and extension excursion of the neck during propulsion of the 2nd step and greater hip flexion angle at foot strike of the 3rd step (r2 =0.804, p < 0.001). SignificanceFaster acceleration was observed when participants transitioned from an upright posture to greater forward trunk lean in the early phase of acceleration. Training the run-to-sprint transition, which was shown to have the greatest increase in velocity over the first 5 m, may be encouraged as a sports specific exercise.

68-LB: Early Pharmacological Intervention (EPIC) to Preserve Beta-Cell Function in Prediabetes (PreDM)

Beta cell failure is the key pathophysiologic determinant in progression from PreDM to type 2 diabetes (T2D). Lifestyle modifications frequently are insufficient to prevent T2D onset and drugs that modify disease progression by targeting pathophysiologic defects in PreDM may be required. Methods: EPIC seeks to answer whether a specific drug provides greater benefit to prevent PreDM progression and to assess the effect of two years of treatment with antidiabetic drugs in 200 individuals with IFG and/or IGT on insulin sensitivity (IS) and beta cell function (BCF). At baseline, participants received 2h-OGTT and two-step hyperglycemic clamp (HC) (+125 and +400 mg/dl) with GLP-1RA infusion. Subjects then were randomized to metformin (MET), pioglitazone (PIO), saxagliptin (SAXA) or dapagliflozin (DAPA). 55 participants have completed the intervention (35F/20M; age = 51 ± 3 ys) Matsuda Index of IS was quantitated from OGTT. Beta Cell Function (BCF) was quantitated: (i) from OGTT as (ΔC-Pep/ΔG) x (Matsuda) and (ii) from HC as ΔC-Pep (First Phase, AIR x Matsuda; ΔC-Pep (Second Phase, +400 mg/dL x Matsuda; and (Second Phase + Exenatide) x Matsuda. Results: A1c did not change significantly in any group, while FPG (106 ±4 to 100 ± 3 mg/dl) and 2h PG (150 ±8 to 141 ± 11) decreased significantly in all groups (p&amp;lt;0.05 for PIO &amp;gt; SAXA). Matsuda Index increased in all groups (p&amp;lt;0.01 for PIO vs all other groups). Weight increased significantly in PIO (+2.5kg p&amp;lt;0.05), did not change with SAXA, decreased with DAPA and MET (both p = NS). BCF during OGTT tended to increase in all groups (p&amp;lt;0.10 for trend). No significant changes in AIR, second phase (+400 mg/dl), and second phase (+400) + Exenatide were seen for MET, SAXA, DAPA, but significantly increased with PIO (AIR 7.1 to 22.8; 2ND STEP 10 to 45.4; 2nd STEP + Exenatide 19 to 79 (all p &amp;lt;0.01). Conclusion: Early drug intervention in prediabetes with pioglitazone preserves beta cell function and improves insulin sensitivity better than MET, SAXA, and DAPA. Disclosure A. Chavez: None. A. Merovci: None. S. Neppala: None. L. A. Cruz Moreno: None. G. Baskoy: None. F. M. Acosta: None. A. A. Hansis-Diarte: None. C. L. Puckett: None. J. M. Adams: None. M. Abdul-Ghani: None. C. L. Triplitt: Speaker's Bureau; Novo Nordisk. E. Cersosimo: None. R. A. DeFronzo: Speaker's Bureau; AstraZeneca. Advisory Panel; AstraZeneca, Bayer Inc., Boehringer-Ingelheim, Novo Nordisk. Research Support; AstraZeneca, Boehringer-Ingelheim, Merck &amp; Co., Inc. Funding National Institutes of Health (R01DK024092-3AZ, ISSDAPA0002)

Sodium concentration imaging in dermis layer by square-wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT)

In this study, sodium concentration in the dermis layer is imaged by the square wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT). The SW-oEIT with SVT consists of three steps which are (1) voltage measurement, (2) spatial voltage thresholding, and (3) sodium concentration imaging. In the 1st step, the root mean square voltage is calculated based on the measured voltage under the square wave current through the planar electrodes on the skin domain Ω. In the 2nd step, the m-th measured voltage is converted to a compensated voltage v * based on the voltage electrodes distance and threshold distance in order to highlight the region of interest of the dermis layer In the 3rd step, sodium concentration is imaged by the Gauss-Newton reconstruction method. The SW-oEIT with SVT was applied to multi-layer skin simulation and ex-vivo experiments under various dermis sodium concentrations c in the range of 5–50 mM. As an image evaluation result, the spatial mean conductivity distribution in is successfully determined as increasing c on both simulations and experiments. The relationship between and c was evaluated by the determination coefficient R 2 and the normalized sensitivity The optimized with the highest evaluation values of 0.84 and 0.83 is under the condition of = 2 mm. Based on the signal evaluation, the SW-oEIT with SVT has a 15.32% higher correlation coefficient CC compared to the conventional oEIT based on sinewave injection.

Dechlorination during pyrolysis of plastics: Effect of municipal plastic waste composition

In order to close the loop in chemical recycling via pyrolysis, products must meet strict limits for halogen content to be used in conventional petrochemical processes. By integrating dechlorination as an integral part of pyrolysis, results show that the efficiency of dechlorination, both via stepwise pyrolysis and dechlorination agents, is significantly decreased in the presence of PET or cellulose in the feedstock. Product analysis showed that Cl reacts with formed oxygenated substances, some of which remain in the reactor during the 1st step at 350 °C and subsequently pass into the final liquid product. This increases the requirements for applied dechlorinating agents during the 2nd pyrolysis step. Novel agents have to therefore cope with a wide range of chlorinated hydrocarbons. By combining acidic β-zeolite with alkali hydrotalcite in a 1:1 ratio, a synergic effect towards dechlorination was observed, increasing individual efficiency by about 12% and 6%, respectively. Combining stepwise pyrolysis, which removed 38% of Cl on average, with the mentioned mixture of agents, 95% efficiency and 12.2 ± 1.2 ppm of Cl were obtained in the final liquid product. Such a level of dechlorination may be sufficient, considering that the pyrolysis liquid will be diluted in conventional petrochemical feedstocks.

Molecular Layer Deposition (MLD) of a Blocked Mercapto Silane on Precipitated Silica

Chemically modified silica is widely used as a reinforcing filler in elastomers. The modification is generally done in situ while preparing the rubber. However, in order to increase the efficiency and facilitate the mixing process, the silica can be pre-treated by a 2-step molecular layer deposition. The precursors for the modification are 3-mercaptopropyl-triethoxysilane (MPTES) and octanoyl chloride (OC) to react with MPTES and form a blocked silane. The precipitated silica nanofiller was successfully treated with MPTES and showed a self-limiting behavior: saturation occurred at 2.7%. Furthermore, DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analysis confirmed the successful deposition of MPTES on the silica surface by showing the -SH peak that appeared after the reaction of MPTES and silica. In the second step, OC was introduced to form a thioester on the surface of the MPTES-treated silica, controlling the reactivity of the mercapto group from MPTES by blocking it to prevent a negative influence on the processing behavior of the rubber. Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS) analytical results confirmed the deposition of the blocked mercapto silane on the silica. TGA results demonstrated the self-limiting behavior of OC, and DRIFTS and XPS proved the thioester formation. A thioester peak after the 2nd reaction step with OC appeared. At the same time, the disappearance of the -SH signal from the MPTES was observed, indicating the formation of the blocked mercapto silane structure. Transmission electron microscopy results showed that the treated silica has a well-distributed carbon and sulfur deposition after MPTES/OC treatment.

FUZZY TOPSIS IN SELECTING LOGISTIC HANDLING OPERATOR: CASE STUDY FROM POLAND

Reliable and effective selection of logistic handling operator is a particularly demanding process due to the short reaction time or high level of accompanying stress. Moreover, diversification of transported cargo makes use of classical indicators and methods of carrier selection highly unsatisfactory for decision-makers. To solve this problem, managers are seeking multi-criteria decision methods that improve the decision-making process related to the selection of the carrier and reduce the risk indicator related to the incorrect implementation of the transport order. Thus, in this paper, we present a Multi-Criteria Decision-Making (MCDM) approach for selecting logistic handling operators under partial or incomplete information (uncertainty) and taking into account the different type of transported cargo. The proposed approach comprises 2 main steps. In the 1st step, we identify the input parameters, mainly connected with criteria for carrier selection depending on the type of transported cargo. In the 2nd step, experts provide linguistic ratings to the potential alternatives against the selected criteria and the best alternative is chosen. At this stage, the fuzzy Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) approach is used. Later, the applicability of the developed method is presented based on the chosen case company. The comparison of classical and fuzzy approaches to decision-making process is also given.

Reliability Assessment Methodology of Blast Protective Steel Moment Resisting Frame Using NiTi SMA-based Connection

This paper proposes a methodology framework for the reliability assessment of smart steel Moment Resisting Frame structures (MRFs) equipped with Nickle Titanium Shape Memory Alloy (NiTi SMA) connections subjected to blast loading. The reliability assessment framework is formulated based on a two-step approach algorithm. In the 1st Step, the Monte Carlo Latin Hypercube Sampling Strategy simulation (MC-LHS) is adapted to generate the uncertain parameters sample points. Considering the numerical simulations, the 2nd Step employs simplified performance functions and the generated random outcomes from the 1st Step. The proposed reliability approach is verified against direct Monte Carlo Simulation (MCS) and First-Order Reliability Method (FORM). The performance functions are columns’ axial force and bending moments, rotation capacity at the connections, and Inter-Story Drift Ratio (ISDR). Throughout the development of the reliability assessment, the probabilistic models are parametrized on geometrical properties, material properties, vertical loads, model errors, and charge weights. The developed reliability framework is applied to a prototype 4-story smart MRF. The structural safety level is obtained in terms of the Reliability Index (β). The results show that the reliability framework provides an accurate and efficient structural collapse prediction of the MRFs equipped with NiTi SMA-based connections. Finally, sensitivity analysis is performed to indicate the sensitivity of building collapse to blast wave characteristics, material strength, vertical gravity loads, and column profile dimensions. The sensitivity analysis results also confirm the efficiency of the proposed reliability framework in observing the highly sensitive parameters, which is explosive charge weight.

고려시대 묘역식분묘의 위계와 특징

In this study, tombs with graveyard facilities were classified into graveyard-typed tombs and divided into three stages to understand their changes. In the 1st step before the 12th century, graveyard-typed tombs which had been constructed around Gaegyeong gradually spread to Yanggwang-do, south of Gyeonggi, with small sized graveyard-typed tombs only. In the 2nd step, from the 13th to the middle of the 14th century, tombs began to be built throughout South Korea in earnest and medium sized graveyard-typed tombs appeared. In the 3rd step of the late Goryeo Dynasty to the early Joseon Dynasty. ranging from the late 14th century to the middle of the 15th century, the number of the graveyard-typed tombs recorded the highest and it is possible to see the large sized tombs.&#x0D; The hierarchies in the graveyard-typed tombs were classified based on the similarities in the tombs for royals and officials. The type Ⅰd2·Ⅰe2·Ⅱb2 may be referred to as the higher and the type Ⅱb1·Ⅱc1·Ⅱd1 as the lower types.&#x0D; It is assumed that the buried of the graveyard-typed tombs after the 12th century were those of the upper middle class that could use the compulsory labor. In particular, tombs of the higher hierarchy are regarded to be the ones for the gentry(Sajok) who came from the central government and moved to certain region. Accordingly, formative diversity in the higher hierarchy can be interpreted to be resulted from differences in rank of the gentry and hierarchy of their families. Furthermore, the status of the local officials(Hyangri) began to be lowered after the 12th century and the graveyard-typed tombs for the lower hierarchy may be constructed under the influence of the tombs for the officials.&#x0D; On the other hand, graveyard-typed tombs tended to be located mainly at a big town along the traffic networks such as Yeok-ro and Joun-Ro. Besides, relics from the island areas of Yanggwang-do show that graveyard-typed tombs had the different forms according to construction groups. The study reveals that at Jeolla-Do and Gyeongsang-Do there was a difference in the number of the graveyard-typed tombs due to the influence of Eight Injunctions by Taejo, exploitation of Jeolla-Do and the growth of the emerging gentry at Gyeongsang-Do. Besides. at Tamla there were more higher types than in land under the influence of Yuan. At Gyoju-Do and Donggye, it is not possible to see the graveyard-typed tombs since rough terrains prevented local officials from growing up.

Regenerative Strategy of Gold Electrodes for Long-Term Reuse of Electrochemical Biosensors.

Gold is of considerable interest for electrochemical active surfaces because thiol-modified chemicals and biomolecules can be easily immobilized with a simple procedure. However, most gold surfaces are damaged with repetitive measurements, so they are difficult to reuse. Here we demonstrate a novel electrochemical cleaning method of gold surfaces to reuse electrodes with a simple protocol that is easy and nontoxic. This electrochemical cleaning consists of two steps by using different solutions. The 1st step is a cyclic voltammetry sweep using a very low concentration of sulfuric acid, and the 2nd step is a cyclic voltammetry sweep using potassium ferricyanide. Different cleaning methods were also considered for comparison. Consequently, after assembling and desorption of the cell and antigen, the changes in gold electrode performance, as immunosensor and cytosensor, were investigated by electrochemical impedance and cyclic voltammetry. It was found that repetitive measurement is possible until five times while maintaining the reproducibility. It is believed that this method is capable of enabling reuse of gold electrodes and can be used for long-term and accurate monitoring of biological effects, especially at a low cost.

Effects of Processing Delays in Different Coverages on the Image Quality of Photostimulable Phosphor Plates With Acteon and Digora Scanners

Background: Delay in the processing of photostimulable phosphor storage plates (PSP) is a common occurrence in crowded clinics. Accordingly, the effects of processing delays in different coverages on the image quality of photostimulable PSPs were investigated with Acteon and Digora scanners. Methods: Three Acteon (group A) and three Digora (group B) PSPs were used in this in vitro study. Each group had three subgroups according to three coverages, including protective box (A1 , B1 ), semitransparent (A2 , B2 ), and original dark case plates (A3 , B3 ). An aluminum step wedge was subjected to constant exposure conditions. The exposed plates were immediately processed with their corresponding scanner device (the golden standard), 5, 10, 20, 30, 40, and 60 minutes after exposure. The average gray level information of the 2nd, 5th, and 8th steps of the Al wedge was considered as the mean gray values (MGVs) of each wedge. The difference between the gray values of the 8th and 2nd steps was measured as image contrast. Results: There was a significant difference between the contrast and MGVs of Acteon and Digora PSPs at all processing delay times (P&lt;0.05). In general, there was no significant difference in the image MGVs and contrast between subgroups in any of the scanners (total P&gt;0.05). In each subgroup, MGVs increased, while contrast decreased by increasing the processing delay time; the difference was significant except for the MGVs in the first 5 minutes of A1 (P=0.12) and A3 (P=0.06). Conclusions: Thus, the type of scanner was effective on image quality; the type of PSP coating in the first few minutes could affect the rate of image quality loss. However, the scan time had a greater effect on the amount of image loss.

Two step calibration method for ozone low-cost sensor: Field experiences with the UrbanSense DCUs

Urban air pollution is a global concern impairing citizens' health, thus monitoring is a pressing need for city managers. City-wide networks for air pollution monitoring based on low-cost sensors are promising to provide real-time data with detail and scale never before possible. However, they still present limitations preventing their ubiquitous use. Thus, this study aimed to perform a post-deployment validation and calibration based on two step methods for ozone low-cost sensor of a city-wide network for air pollution and meteorology monitoring using low-cost sensors focusing on the main challenges. Four of the 23 data collection units (DCUs) of the UrbanSense network installed in Porto city (Portugal) with low-cost sensors for particulate matter (PM), carbon monoxide (CO), ozone (O3), and meteorological variables (temperature, relative humidity, luminosity, precipitation, and wind speed and direction) were evaluated. This study identified post-deployment challenges related to their validation and calibration. The preliminary validation showed that PM, CO and precipitation sensors recorded only unreliable data, and other sensors (wind speed and direction) very few data. A multi-step calibration strategy was implemented: inter-DCU calibration (1st step, for O3, temperature and relative humidity) and calibration with a reference-grade instrument (2nd step, for O3). In the 1st step, multivariate linear regression (MLR) resulted in models with better performance than non-linear models such as artificial neural networks (errors almost zero and R2 > 0.80). In the 2nd step, the calibration models using non-linear machine learning boosting algorithms, namely Stochastic Gradient Boosting Regressor (both with the default and post-tuning hyper-parameters), performed better than artificial neural networks and linear regression approaches. The calibrated O3 data resulted in a marginal improvement from the raw data, with error values close to zero, with low predictability (R2 ∼ 0.32). The lessons learned with the present study evidenced the need to redesign the calibration strategy. Thus, a novel multi-step calibration strategy is proposed, based on two steps (pre and post-deployment calibration). When performed cyclically and continuously, this strategy reduces the need for reference instruments, while probably minimising data drifts over time. More experimental campaigns are needed to collect more data and further improve calibration models.

Application of the solid-state fermentation process and its variations in PHA production: a review.

Solid-state fermentation (SSF) is a type of fermentation process with potential to use agro-industrial by-products as a carbon source. Nonetheless, there are few studies evaluating SSF compared to submerged fermentation (SmF) to produce polyhydroxyalkanoates (PHAs). Different methodologies are available associating the two processes. In general, the studies employ a 1st step by SSF to hydrolyze the agro-industrial by-products used as a carbon source, and a 2nd step to produce PHA that can be carried out by SmF or SSF. This paper reviewed and compared the different methodologies described in the literature to assess their potential for use in PHA production. The studies evaluated showed that highest PHA yields (86.2% and 82.3%) were achieved by associating SSF and SmF by Cupriavidus necator. Meanwhile, in methodologies using only SSF, Bacillus produced the highest yields (62% and 56.8%). Since PHA (%) does not necessarily represent a higher production by biomass, the productivity parameter was also compared between studies. We observed that the highest productivity results did not necessarily represent the highest PHA (%). C. necator presented the highest PHA yields associating SSF and SmF, however, is not the most suitable microorganism for PHA production by SSF. Concomitant use of C. necator and Bacillus is suggested for future studies in SSF. Also, it discusses the lack of studies on the association of the two fermentation methodologies, and on the scaling of SSF process for PHA production. In addition to demonstrating the need for standardization of results, for comparison between different methodologies.

Effect of a two-step fermentation method with rumen liquor on protein quality of wheat bran and rice bran to use as poultry feed

The availability of high quality protein rich feed in many developing countries is limited as well as expensive. Low-quality agro-industrial by-products, i.e., rice bran (RB) and wheat bran (WB), are therefore used as poultry feed irrespective of their low protein content. The main objective of the present study was to improve the protein content and the amino acid profiles of these by-products through rumen liquor mixed fermentation process. A two-step fermentation of some agricultural by-products (e.g., WB and RB) was performed in a controlled environment for 3 h and 6 h. In the 1st and 2nd steps, feedstuff (brans), McDougall buffer as well as collected rumen liquor were mixed with following the proportion of 1:2:3, respectively. After fermentation, brans were dried at 100 °C in an oven. Dried sample were used to analyze the crude protein (CP) as well as amino acid (AA) content. In 1st and 2nd fermentation of the WB, CP content increased 3.3 ± 0.2% (3 h), 4.3 ± 0.2% (6 h) and 7.7 ± 0.1% (3 h), 8.5 ± 0.1% (6 h), respectively compared to control. On the other hand, RB protein content increased by 3.3 ± 0.1% (3 h), 0.8 ± 0.1% (6 h) and 7.3 ± 0.3% (3 h), 4.0 ± 0.1% (6 h) in the 1st and 2nd fermentation step, respectively compared to control. Majority of the AA increased compared to control during the 1st fermentation step for RB and WB. However, In WB, some of the AA did not show significant difference. A number of AA were decreased after the 2nd step for both RB and WB except Methionine, which increased in both steps. In 1st and 2nd steps, Methionine increased by 24.9 ± 5.1% (3 h), 25.9 ± 5.8% (6 h) for WB and 12.2 ± 3.2% (3 h), 13.0 ± 4.5% (6 h) for RB, respectively compared to control. In conclusion brans protein and amino acid quality optimization might be possible through methodical rumen liquor mixed fermentation process for better utilization as poultry diet.

Development of an integrated glycine-based process for base and precious metals recovery from waste printed circuit boards

The present study developed an integrated glycine-based process to recover metals from waste printed circuit boards at high solid contents (10–15%). A novel glycine-ammonia leaching was used to selectively extract >99% copper, >85% zinc and around 50% lead at room temperature. Ammonia played a key role, increasing the copper solubility in solution (>40 g/L), shortening leaching time from 72 to 24 h, and also acting as a pH modifier. The 2nd leaching step utilised cyanide-starved glycine where extractions of 70–90% for gold and silver, and >50% for palladium were obtained. The remaining metals from the previous steps were removed by ferric sulfuric acid leaching, with/without thiourea. In the presence of thiourea, 70–95% of remaining base and precious metals were removed. Overall, the metals with major economic value were all extracted at >99% for copper, >80% for gold, >90% for silver and >85% for palladium.

Transcript-specific determinants of pre-mRNA splicing revealed through in vivo kinetic analyses of the 1st and 2nd chemical steps

We generate high-precision measurements of the invivo rates of both chemical steps of pre-mRNA splicing across the genome-wide complement of substrates in yeast by coupling metabolic labeling, multiplexed primer-extension sequencing, and kinetic modeling. We demonstrate that the rates of intron removal vary widely, splice-site sequences are primary determinants of 1st step but have little apparent impact on 2nd step rates, and the 2nd step is generally faster than the 1st step. Ribosomal protein genes (RPGs) are spliced faster than non-RPGs at each step, and RPGs share evolutionarily conserved properties that may contribute to their faster splicing. A genetic variant defective in the 1st step of the pathway reveals a genome-wide defect in the 1st step but an unexpected, transcript-specific change in the 2nd step. Our work demonstrates that extended co-transcriptional association is an important determinant of splicing rate, a conclusion at odds with recent claims of ultra-fast splicing.

New method to optimize no-load noise of power transformers based on core design &amp; transformer operating conditions

This paper introduces a new algorithm to calculate and optimize no-load noise (sound pressure) of power transformers, and to identify iron sheet parameters. The calculation consists of two steps: the 1st step consists in calculating an initial sound pressure level (A-Evaluation) which has approx. 70 % accuracy within a tolerance interval of ±2dB (A). The 2nd step consists in estimating the expected deviation from the initial calculation to reach 90 % accuracy in the final results. This deviation could be due to material handling, quality tolerance, core manufacturing, etc. The optimization process consists of two parts: the 1st part takes place before choosing a certain iron sheet for calculation to identify the sheet parameters required for computational accuracy (“Sheet Optimization”). The 2nd part consists in considering a core design with an undesirable sound pressure level in order to reduce it to an acceptable limit. This part takes into account the other limitations such as no-load losses and transformer dimensions (“Design Optimization”). For new iron sheets in the market, there is no measurement history to rely on. However, the algorithm is also capable of identifying the sheet parameters for calculation based on the available algorithm data base and the magnetostriction measurements of the iron sheet manufacturer.

Health effects and metabolic pathway of arsenic in children

Our six years of field experience in Bangladesh showed that normally children under 11 years of age do not show arsenical skin manifestations. However, we have observed a few exceptions when (1) the arsenic content in water consumed by children is very high (≥1,000 µg/L) and (2) the arsenic content is not very high, but the children get poor nutrition. It appears that although 6.12% of 4,864 children showed arsenic skin lesions but hair and nail analysis of children (below 11 years) with or without arsenical skin lesions from affected villages of Bangladesh showed that 84% of the children had arsenic in hair more than the toxic level and 89% in nail above normal level. It appears that children living in arsenic affected villages have higher arsenic body burden but less dermatological symptoms. The value of arsenic excretion and arsenic intake per kg of body weight ratio for adults is 0.53 while that of the children is 0.69. This indicates total arsenic excretion is higher for children per kg of body weight than adults. The average values (n = 18) for speciation of arsenic in children urine are 15.60% In-As, 10.64% MMA, and 73.76% DMA. Overall percentage of MMA is higher, and DMA is lower in adults than children (average % MMA is 17.20 vs. 10.64 and % DMA is 64.62 vs. 73.76%, respectively). Therefore, the 2nd methylation step (MMA to DMA) could be more active in children than adults. The results indicate that the first reaction of the metabolism pathway is more active in adults than children, basically in adult’s male. Also shows a significant (t-test positive) increase in the values of the DMA/MMA ratio in children compared to adults of the exposed group (8.15 vs. 4.11, respectively). Moreover, it is also observed that the second methylation step in the arsenic metabolic pathway is more active in children than adults. Because there is no significant difference of the values of MMA/iAs ratio, but the values of DMA/MMA ratio are significantly different between adults and children of the exposed group (0.92 vs. 0.73 for MMA/Asi and 4.11 vs 8.15 for DMA/MMA, respectively). Thus, from these results we may conclude that children retain arsenic shorter in their body comparing adults.

Gold leaching from waste mobile phone PCBs in a solution mixture of sodium persulfate and potassium iodide

Gold is one of the most fascinating resources in the waste mobile phones’ printed circuit boards (WMPPCBs). In this study, a new process for recovering Au from WMPPCBs by the Na2S2O8-KI system was developed. This process comprises a two-stage leaching process to provide a separation of copper and gold from WMPPCBs. 98% Cu and 78% Fe were dissolved by the 1st base metals' leaching (H2SO4-H2O2 leaching) step. The leaching of gold from the solid reside of 2nd leaching step was performed to study the effect of Na2S2O8 concentration, KI concentration, temperature, and solid-liquid ratio in Na2S2O8-KI leaching system. The results showed that removing most of Cu greatly promoted the leaching efficiency of gold in Na2S2O8-KI leaching system. The mechanism of gold leaching was studied by the thermodynamic analysis. Leaching kinetics data showed that gold leaching followed an intermediate-controlled mechanism with Ea, 30.3 kJ mol−1. The best conditions for leaching of gold in Na2S2O8-KI system were determined to be 0.02 M Na2S2O8, 0.15 M KI, 40 ℃, a solid-liquid ratio of 1: 20 (g/mL), and a stirring speed of 200 rpm. Under the optimal leaching parameters, the efficiency of gold leaching from WMPPCBs attained 96% after 120 min. Due to the non-toxic and low-cost properties of Na2S2O8, the Na2S2O8-KI leaching process is more sustainable than conventional processes (cyanide leaching et al.).