Total Reaction Time Research Articles

Ultrafast charge separation in a WC@C/CdS heterojunction enables efficient visible-light-driven hydrogen generation.

The rapid recombination of photogenerated carriers and strong photocorrosion have considerably limited the practical application of CdS in the field of photocatalysis. Loading a cocatalyst has been widely utilized to largely enhance photocatalytic activity. In the present work, a WC@C cocatalyst was prepared by a novel molten salt method and explored as an efficient noble-metal-free cocatalyst to significantly enhance the photocatalytic hydrogen evolution rate of CdS nanorods. The WC@C/CdS composite photocatalyst with a 7 wt% content of WC@C showed the highest photocatalytic hydrogen evolution rate of 8.84 mmol g-1 h-1, which was about 21 and 31 times higher than those of CdS and 7 wt% Pt/CdS under visible light irradiation. A high apparent quantum efficiency (AQY) of 55.28% could be achieved under 420 nm monochromatic light. Furthermore, the photocatalytic activity of the 7 wt% WC@C/CdS photocatalyst exhibited good stability for 12 consecutive cycles of the photocatalytic experiment with a total reaction time of 42 h. The excellent photocatalytic performance of the photocatalyst was attributed to the formation of a Schottky junction and the loading cocatalyst, which not only accelerated the separation of the photogenerated carrier but also provided a reactive site for hydrogen evolution. This work revealed that WC@C could act as an excellent cocatalyst for enhancing the photocatalytic activity of CdS nanorods.

Mediating Effects of Fitness-For-Work on Fatigue for Mining (Heavy Equipment) Technicians in Indonesia

Fatigue has been considered as a major contributing factor to workplace accidents. While most previous studies on fatigue have been conducted in a laboratory setting, the current study was performed in the mining region of Kalimantan, Indonesia. This study assessed the fitness-for-work and fatigue experienced by 21 maintenance technicians at two mining workshops. This study focused on three independent variables: work shift (day shift and night shift), work locations (non-remote area and remote area), and individual fitness. Heart rate and the Psychomotor Vigilance Test (PVT) data (in terms of total error and mean reaction time) were collected at the beginning, middle, and end of work. Covariance analysis was applied to determine the effect of the independent variables on fitness-for-work and fatigue. The results show that work shift and individual fitness significantly influence fitness-for-work (p 0.05). However, none of the independent variables significantly affect fatigue, even though fitness-for-work and fatigue are strongly correlated (r = 0.69, p 0.05). These results proved the role of fitness-for-work as an intermediate factor in fatigue. We suggest that there should be a shift in strategy for reducing the risk of accident-related fatigue, from fatigue monitoring directly to fitness-for-work screening. Eventually, the practical implementations of the findings are discussed comprehensively.

Study of treating the vegetable oils in artificial water using advanced oxidation process

AOPs homogenized advanced oxidation process was studied in Fenton and Photo-Fenton on the treatment of artificial water from vegetable oil contaminants. Several variables were studied: time, pH, mixing speed, and a dose of catalysis (Fe2SO4.7H2O).The best conditions are obtained by studying experiments. Fenton and Photo-Fenton process work at an acidic medium (pH=3.5). The optimum mixing speed at (1000 rpm) for the Photo-Fenton process and (500 rpm) for the Fenton. When concentration of H2O2 was (500 mg/L) obtained the concentration of Fe2SO4.7H2O for the photo-Fenton process = (50 mg/L), and for the Fenton process = (250 mg/L).The Fenton process gave a maximum efficiency of removal of vegetable oils of 95.2% for Corn oil (COD from 12800 to 610 mg/L), 94.5% for Castor oil, while 57.5% for Coconut oil after the total reaction time (180 minutes).The Photo- Fenton process gave an efficiency of removal: 93% for Corn oil (COD from 12500 to 870 mg/L), 83.8% for Castor oil, while 61.6% for Coconut oil.As for the real wastewater, the treatment was acceptable and achieved an efficiency of 89.2%, and 83.8% for Fenton, and Photo-Fenton processes respectively.

The Mechanism of Word Satiation in Tibetan Reading: Evidence from Eye Movements.

Two eye-tracking experiments were used to investigate the mechanism of word satiation in Tibetan reading. The results revealed that, at a low repetition level, gaze duration and total fixation duration in the semantically unrelated condition were significantly longer than in the semantically related condition; at a medium repetition level, reaction time in the semantically related condition was significantly longer than in the semantically unrelated condition; at a high repetition level, the total fixation duration and reaction time in the semantically related condition were significantly longer than in the semantically unrelated condition. However, fixation duration and reaction time showed no significant difference between the similar and dissimilar orthography at any repetition level. These findings imply that there are semantic priming effects in Tibetan reading at a low repetition level, but semantic satiation effects at greater repetition levels, which occur in the late stage of lexical processing.

Choline alleviated perinatal fluoride exposure-induced learning and memory impairment through α4β2 nAChRs and α7 nAChRs in offspring mice.

Fluoride pollution is widely present in the living environment. As a critical period of brain development, the perinatal period is extremely vulnerable to fluoride. Studies have found that choline can protect the brain's memory and enhance the ability to focus. However, the effect of choline on perinatal fluoride-induced nerve damage remains unclear. Therefore, 32 Kunming newly conceived female mice and their offspring mice were randomly divided into control, NaF, LC + NaF, and HC + NaF groups, and the HE staining, Y-maze test, RT-PCR, western blotting, immunohistochemistry, etc. were used in this study. The results showed that fluoride decreased the brain organ coefficients and brain protein content (p < 0.05, p < 0.01), and caused histomorphological damage in the hippocampus and cortex, which suggested that fluoride affected the development of the brain and damaged the brain. Moreover, the results of the Y-maze test showed that fluoride increased the number of learning days, error reaction time, and total reaction time, and decreased the AchE activity in the brain (p < 0.05, p < 0.01), which indicated that fluoride reduced the learning and memory ability of the mice. Besides, the results showed that fluoride decreased the mRNA and protein expression levels of α4β2 nAChRs and α7 nAChRs in the hippocampus and cortex (p < 0.05, p < 0.01). However, perinatal choline supplementation reversed the aforementioned fluoride-induced changes. In short, these results demonstrated that choline alleviated perinatal fluoride-induced learning and memory impairment, which will provide a rationale for the mitigation and prevention of fluoride-induced brain damage.

The effect of fatigue on electromechanical response times in basketball players with and without persistent low back pain

Typically, athletes alter movement mechanics in the presence of back pain, but the effect of these changes on lower extremity injury risk is not well understood. This study aimed to compare the effect of fatigue on electromechanical response times during a choice reaction task in basketball players with and without persistent low back pain. Twenty-four male basketball players participated. Total reaction time (TRT), premotor time (PMT), and electromechanical delay (EMD data were recorded before and after fatigue. The chronic low back pain (CLBP) group had significantly longer EMD in Med gastrocnemius (p = 0.001) and Tibialis anterior (p = 0.001), and shorter EMD in Vastus Lateralis (p = 0.001), Vastus Medialis Oblique (p = 0.003), and Semitendinosus (p = 0.025) muscles after fatigue. PMT in the CLBP group had longer than the Non-CLBP in Vastus Lateralis (p = 0.010), Vastus Medialis Oblique (p = 0.017), Semitendinosus (p = 0.002). Also, TRT was longer in knee flexion (p = 0.001) and ankle plantarflexion (p = 0.001) muscle groups. The different effects of fatigue on electromechanical response times of the knee and ankle in people with CLBP may represent the effect of an axial injury on lower extremity injury risk factors in situations of higher cognitive load, similar to competitive play.

Extended Luenberger observer for a biodiesel production process with heterogeneous catalyst

The biodiesel production process requires low-cost and real-time monitoring. In this document, an extended Luenberger observer was designed to provide on-line estimation of the concentration of triglycerides, methanol, biodiesel, and glycerol. To this end, a mathematical model based on energy and mass balance equations as well as the global transesterification reaction in a batch reactor was considered. The model consists of two nonlinear differential equations, one output equation, and four complementary equations. The simplification of the model was used through a linearization procedure, considering two state variables (reaction rate and temperature) and one output variable (temperature). This procedure allowed to use estimation strategies typical of linear systems. The LQR method was used to calculate the gain observer. A fast convergence (compared to the total reaction time) of the observer was obtained despite varying the initial conditions up to 30%. Thus, it was concluded that the extended Luenberger observer, using temperature as the only output, allows estimating the conversion of triglycerides to biodiesel.

Does intermittent theta burst stimulation improve working memory capacity? A randomized controlled cross-over experiment

ObjectiveIt has been hypothesized that intermittent theta burst stimulation (iTBS) can produce a memory-enhancing effect by inducing long-term potentiation (LTP)-like plasticity in the dorsolateral prefrontal cortex (DLPFC). However, the hemispheric difference by which iTBS modulates working memory in healthy adults has not been well investigated. The objective of the present study is to investigate the effects of iTBS on the left dorsolateral prefrontal cortex (LDLPFC) and right dorsolateral prefrontal cortex (RDLPFC) on working memory performance in healthy adults. MethodsIn this randomized cross-over experiment, 31 right-hand dominant healthy adults received a single-session of iTBS to their LDLPFC, RDLPFC and sham stimulation, in three different visits separated by a seven-day waiting period. Working memory capacity was assessed before and immediately after stimulation, by using 2-and 3-back tasks. ResultsAfter stimulation, significant time effects were found in overall accuracy when performing both 2- (p = 0.013) and 3-back tasks (p = 0.027), as well as the total reaction time during 3-back tasks (p = 0.021). Analysis of secondary outcomes showed an increase in the number of correction rejections in 2-back tasks (p = 0.009). However, all of the time-by-group interaction effects were not significant. ConclusionThis experiment did not find any additional memory-enhancing effects with a single-session of iTBS to either the RDLPFC or the LDLPFC in healthy adults beyond the practice effects.

An improved method for rapid identification of hook effect samples in HBsAg quantitative assay

Quantitative hepatitis B surface antigen assay is widely used for diagnosis of hepatitis B virus infection; however, specimens with high levels of the antigen can cause false-negative results (Hook effect), which needs to be resolved. The hook effect samples and non-hook effect samples were detected on the LiCA® 500 instrument using three methods, viz., 1, 2, and 3. Method 1, the currently used procedure, was performed in two steps with a total reaction time of 25 min in a final volume of 250 µL: first incubation was with two reagents for 15 min and then with one other reagent for 10 min. In Method 2, all three reagents were added in one step with a final volume of 250 µL, and the total reaction time was still 25 min. In Method 3, the improved method, all three reagents were added in one step while the final volume was only 130 µL and the total reaction time was only 1 min. Signal values of the non-hook effect samples obtained using Method 2 were significantly lower than those with Method 1, showing competitive inhibition. The hook effect samples tested with Method 2 approximated those obtained using Method 1. Method 3 took 1 min and differentiated hook effect samples successfully, similar to the results with Method 2 which took 25 min. Changing the timing of one reagent addition and incubation time in Method 3 provided a rapid and effective method for the identification of hook effect. The results were more clearly distinguishable due to the phenomenon of competitive inhibition. Method 3 can be considered an improvement on the chemiluminescence platform.

Attention impairment in patients with cervical dystonia: An attention network test study.

ObjectiveThe purpose of this study was to investigate attentional network functional characteristics in patients with cervical dystonia (CD).MethodsA total of 29 patients with CD and 26 healthy controls (HCs) were recruited. All subjects participated in the study and underwent the Attention Network Test (ANT), which evaluated the efficiencies of three independent attention networks (alerting, orienting, and executive control), as well as reaction time (RT) and accuracy.ResultsSignificant differences between CD patients (9.86 ± 27.95 ms) and HCs (33.62 ± 23.41 ms) were observed in the alerting network (t = −3.40, p < 0.05). In contrast, the orienting network (t = 0.26, p = 0.79), executive control network (Z = −0.55, p = 0.58), total mean reaction time (t = −2.6, p = 0.79), and total accuracy rate (Z = −1.67, p = 0.09) showed no significant differences between the two groups.ConclusionPatients with CD showed a significant deficit in the alerting network. However, they did not show any deficits in the orienting or executive control network. In addition, the alerting, orienting, and executive control network functions of CD patients were all affected by the severity of torticollis, especially the alerting network function.

Analysis of the Effects of Curculin on Neuronal Cells, Glutamate Transporter Solute Carrier Family 1, Learning and Memory in Alzheimer’s Disease Rats

Our study assessed curculin’s effects on neurons, GLT-1, and behavioral learning ability of AD rats. 40 rats were divided randomly into low curculoside group (CAS1 group), high curculoside group (CAS2 group), normal group (WG group) and model group (GS group) (stereotactic injection of Aβ into hippocampus) followed by analysis of learning ability by Y-maze, GLT-1 level by immunofluorescence histochemistry, neuron morphology by HE staining, GLU content by HPLC, GLT-1 level by western blot, and apoptosis by TUNEL assay. Compared with WG group, GS group had significantly elevated number of exercises and wrong actions, total reaction time and Glu content (20.52±2.09 μmol/L versus 7.51±1.21 μmol/L) and reduced GLT-1 level (0.47±0.06 versus 1.23±0.07) (P &lt; 0.01). In addition, increased apoptosis rate was found in GS group (69.78±9.97) compared to WG group (8.42±2.13) (P &lt; 0.01). Compared with GS group, CAS1 and CAS2 groups had improved changes (P &lt; 0.01) with more improvement in CAS2 group than CAS1 group. In conclusion, curculoside can inhibit GLU expression, reduce neuronal cell apoptosis, and improve the learning ability of AD rats, which may be related to the inhibition of GLT-1 in AD rats.

Capacitive Couple-Based Transient Current Commutation in Solid-State Circuit Breakers

This letter presents a new auxiliary circuit to achieve transient current commutation (TCC) in dc solid-state circuit breakers (SSCBs). The auxiliary circuit consists of two parts: active injection circuits (AIC) and capacitive couplers. There are two contributions. First, coupling capacitors between AIC and the main branch are introduced to prevent short circuit failures in the auxiliary branch. Second, a boost converter-based resonant circuit is presented for AIC to achieve TCC in the main branch through couplers. The presented AIC tunes the duration time and amplitude of injected countercurrent pulses during dc current interruption. The working principle and design procedure of the auxiliary circuit are presented. The proposed topology is verified by experiments of a 2&#x00A0;kV&#x002F;100 A dc SSCB prototype under load current interruption. The experimental results show that the injected pulse current through couplers reaches 110 A, and it decays to zero within 12.5&#x00A0;&#x03BC;s. The total reaction time interval including the communication delay and the AIC current rising delay is 108&#x00A0;&#x03BC;s. Meanwhile, the peak voltages across the main branch and the coupler reach 2099 V and 2193&#x00A0;V, respectively.

Expeditious Access to Morphinans by Chemical Synthesis

AbstractMorphinans are essential medicines derived entirely from poppy supply chains rendered increasingly volatile by climate change. Here, we report a seven‐step, asymmetric chemical synthesis of (−)‐codeine from simple materials that requires a total combined reaction time of fewer than 24 hours. The efficiency of our approach arises from a double‐Heck cyclization reaction that generates two rings and two contiguous stereogenic carbon centres in the one pot. A subsequent photo‐redox hydroamination protocol provides a novel, atom‐economical means for assembling the piperidine D‐ring of codeine. Simple modifications to the closing stages of our sequence offer effective access to pharmacologically valuable derivatives of N‐demethyl codeine. Our work highlights the capacity for contemporary, stand‐alone chemical synthesis regimes to diversify access to essential opiate medicines.

Expeditious Access to Morphinans by Chemical Synthesis.

Morphinans are essential medicines derived entirely from poppy supply chains rendered increasingly volatile by climate change. Here, we report a seven-step, asymmetric chemical synthesis of (-)-codeine from simple materials that requires a total combined reaction time of fewer than 24 hours. The efficiency of our approach arises from a double-Heck cyclization reaction that generates two rings and two contiguous stereogenic carbon centres in the one pot. A subsequent photo-redox hydroamination protocol provides a novel, atom-economical means for assembling the piperidine D-ring of codeine. Simple modifications to the closing stages of our sequence offer effective access to pharmacologically valuable derivatives of N-demethyl codeine. Our work highlights the capacity for contemporary, stand-alone chemical synthesis regimes to diversify access to essential opiate medicines.

A new concept for the production of 11C-labelled radiotracers

BackgroundThe GMP-compliant production of radiopharmaceuticals has been performed using disposable units (cassettes) with a dedicated synthesis module. To expand this “plug ‘n’ synthesize” principle to a broader scope of modules we developed a pressure controlled setup that offers an alternative to the usual stepper motor controlled rotary valves. The new concept was successfully applied to the synthesis of N-methyl-[11C]choline, L-S-methyl-[11C]methionine and [11C]acetate.ResultsThe target gas purification of cyclotron produced [11C]CO2 and subsequent conversion to [11C]MeI was carried out on a TRACERlab Fx C Pro module. The labelling reactions were controlled with a TRACERlab Fx FE module. With the presented modular principle we were able to produce N-methyl-[11C]choline and L-S-methyl-[11C]methionine by loading a reaction loop with neat N,N'-dimethylaminoethanol (DMAE) or an ethanol/water mixture of NaOH and L-homocysteine (L-HC), respectively and a subsequent reaction with [11C]MeI. After 18 min N-methyl-[11C]choline was isolated with 52% decay corrected yield and a radiochemical purity of > 99%. For L-S-methyl-[11C]methionine the total reaction time was 19 min reaction, yielding 25% of pure product (> 97%). The reactor design was used as an exemplary model for the technically challenging [11C]acetate synthesis. The disposable unit was filled with 1 mL MeMgCl (0.75 M) in tetrahydrofuran (THF) bevore [11C]CO2 was passed through. After complete release of [11C]CO2 the reaction mixture was quenched with water and guided through a series of ion exchangers (H+, Ag+ and OH−). The product was retained on a strong anion exchanger, washed with water and finally extracted with saline. The product mixture was acidified and degassed to separate excess [11C]CO2 before dispensing. Under these conditions the total reaction time was 18 ± 2 min and pure [11C]acetate (n = 10) was isolated with a decay corrected yield of 51 ± 5%.ConclusionHerein, we described a novel single use unit for the synthesis of carbon-11 labelled tracers for preclinical and clinical applications of N-methyl-[11C]choline, L-S-methyl-[11C]methionine and [11C]acetate.

One-pot fabrication of poly (ionic liquid)s functionalized magnetic adsorbent for efficient enrichment of phenylurea herbicides in environmental waters

Efficient capture is an essential procedure in the highly sensitive monitoring of phenylurea herbicides (PUHs) in various environmental waters. Herein, a new poly (ionic liquid)s functionalized magnetic adsorbent (PFMA) was conveniently fabricated by means of “one-pot” strategy. The preparation procedure was quite simple by mixing 1-allyl-3-methylimidazoliumbis[(trifluoromethy)sulfonyl]imide, ethylene glycol dimethacrylate, Fe3+, Fe2+, mixed solution of dimethyl sulfoxide/H2O and azobisisobutyronitrile in one pot, and the total reaction time was just 3.0 h which was far shorter than that needed in previous approaches. A series of characterized techniques were employed to observe and inspect the morphology, structure and magnetic properties of prepared PFMA. Results revealed that the adsorbent contained abundant functional groups and superior magnetic property. Combing with magnetic solid-phase extraction (MSPE) format, the resultant PFMA displayed high capture capability towards studied PUHs through multiple interactions, and the enrichment factors were in the range of 126–227. Under the selected extraction parameters, the introduced PFMA/MSPE was combined with HPLC equipped with diode array detector (HPLC/DAD) to measure investigated PUHs at trace levels in various environmental waters. Wide linear range (0.010–200 μg/L), low limit of detection (0.0025–0.015 μg/L) and good precision (RSDs<10%) were achieved. The reliability and practicality of established approach was demonstrated by quantifying trace studied PUHs in various waters. Satisfactory fortified recoveries (80.2–119%) and repeatability were achieved. The results well evidence that the prepared PFMA is a good alternative for capture PUHs, and the introduced approach has wide prospect in the analyzing trace levels of PUHs in water and other complex samples.

Self-assembled monolayer protection of chiral-imprinted mesoporous platinum electrodes for highly enantioselective synthesis.

In modern chemistry, chiral (electro)catalysis is a powerful strategy to produce enantiomerically pure compounds (EPC). However, it still struggles with uncontrollable stereochemistry due to side reactions, eventually producing a racemic mixture. To overcome this important challenge, a well-controlled design of chiral catalyst materials is mandatory to produce enantiomers with acceptable purity. In this context, we propose the synergetic combination of two strategies, namely the elaboration of mesoporous Pt films, imprinted with chiral recognition sites, together with the spatially controlled formation of a self-assembled monolayer. Chiral imprinted metals have been previously suggested as electrode materials for enantioselective recognition, separation and synthesis. However, the outermost surface of such electrodes is lacking chiral information and thus leads to unspecific reactions. Functionalising selectively this part of the electrode with a monolayer of organosulfur ligands allows an almost total suppression of undesired side reactions and thus leads to a boost of enantiomeric excess to values of over 90% when using these surfaces in the frame of enantioselective electrosynthesis. In addition, this strategy also decreases the total reaction time by one order of magnitude. The study therefore opens up promising perspectives for the development of heterogeneous enantioselective electrocatalysis strategies.

Growth kinetics determine the polydispersity and size of PbS and PbSe nanocrystals.

A library of thio- and selenourea derivatives is used to adjust the kinetics of PbE (E = S, Se) nanocrystal formation across a 1000-fold range (kr = 10−1 to 10−4 s−1), at several temperatures (80–120 °C), under a standard set of conditions (Pb : E = 1.2 : 1, [Pb(oleate)2] = 10.8 mM, [chalcogenourea] = 9.0 mM). An induction delay (tind) is observed prior to the onset of nanocrystal absorption during which PbE solute is observed using in situ X-ray total scattering. Density functional theory models fit to the X-ray pair distribution function (PDF) support a Pb2(μ2-S)2(Pb(O2CR)2)2 structure. Absorption spectra of aliquots reveal a continuous increase in the number of nanocrystals over more than half of the total reaction time at low temperatures. A strong correlation between the width of the nucleation phase and reaction temperature is observed that does not correlate with the polydispersity. These findings are antithetical to the critical concentration dependence of nucleation that underpins the La Mer hypothesis and demonstrates that the duration of the nucleation period has a minor influence on the size distribution. The results can be explained by growth kinetics that are size dependent, more rapid at high temperature, and self limiting at low temperatures.

Biodiesel-Alkaline Transesterification Process for Methyl Ester Production

The world needs to increase renewable and alternative fuel sources such as Biomass, Bioethanol, and Biodiesel to compete with fossil fuels. Biodiesel is an important renewable fuel source since it can be used in regular diesel vehicles without requiring engine modifications. Conventional biodiesel production takes around 90 min of reaction time. A longer reaction time is not suitable for commercial production. Furthermore, traditional products such as oil react with biodiesel methoxide to produce a maximum of 90% biodiesel yield. As the catalyst is not involved with the reaction, pure methanol and methoxide (methanol with KOH catalyst) are separately added to the system to enhance the pre-reaction step. By changing the methanol to methoxide ratio, biodiesel is produced, and yield is calculated. The highest yield, which is 95%, is obtained with a 5:15% methanol to methoxide ratio. The total reaction time with the new experimental procedure is only 20 min. That is a significant reduction by saving operating costs such as energy consumption. Produced biodiesel show similar properties to that of standard biodiesel.

Methacrylate and Styrene Block Copolymer Synthesis by Cu‐Mediated Chain Extension of Acrylate Macroinitiator in a Semibatch Reactor

AbstractA process for the well‐controlled growth of acrylates by Cu‐mediated polymerization has been developed, with macroinitiator synthesized continuously in a copper tubular reactor and subsequently chain‐extended in a semibatch reactor without additional copper. Extending this process to methacrylates and styrene, however, has proven difficult due to a significant reduction in reaction rate. This barrier has been overcome by chain‐extending the low molecular weight (Mn of 760 g mol–1) poly(methyl acrylate) macroinitiator with methacrylates and styrene using PMDETA (N,N,N′,N″,N″‐pentamethyldiethylenetriamine) as ligand. Methyl methacrylate conversions of &gt;80% at 70 °C and diethylene glycol methyl ether methacrylate conversions of &gt;90% at room temperature are achieved in 4 h, with the same room temperature conditions successfully applied for controlled chain extensions with butyl methacrylate. Although styrene conversions are slightly lower (60–70%) over 4 h at 85 °C, the rates achieved are substantially higher than achieved in other studies. Hydrophobic–hydrophilic triblock structures are produced through sequential monomer feeds to the semibatch reactor, keeping total reaction time to less than 5 h. The ability to incorporate methacrylates and/or styrene into structured block polymers greatly extends the range of products that can be efficiently synthesized with low copper levels by this process.