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This study combines analysis of both organic and inorganic components in bisphenol A oxidation by MnO 2 in a stirred flow reactor.
AbstractBackground Oculomotor and reaction time tests are frequently used assessments of vestibular symptoms, traumatic brain injury (TBI), or other neurological disorders in both clinical and research contexts. When interpreting these tests it is important to have a reference interval (RI) as a comparison for what constitutes a typical/expected response; however, the current body of research has only limited information regarding normative ranges calculated according to established standards or for a military-specific sample.Purpose The purpose of the present study was to describe RIs for oculomotor and reaction time tests in a cohort of service members and veterans (SMVs) for use as comparators by clinicians and scientists.Research Design Descriptive.Study Sample Participants were prospectively enrolled in the Defense and Veterans Brain Injury Center-Traumatic Brain Injury Center of Excellence 15-year Longitudinal Traumatic Brain Injury Study. Only SMVs without a history of TBI or blast exposure were included in the RI calculations.Data Collection and Analysis The test paradigms included in this analysis were: smooth pursuit, prosaccades, antisaccades, saccades and reaction time, predictive saccades, optokinetic nystagmus, auditory reaction time, and visual reaction time. Nonparametric methods, based on the U.S. Food and Drug Administration's recognized consensus standards, were used to calculate 95% RIs. A comparison between the calculated RIs and those available from previously published research is provided.Results Summary statistics and RIs were calculated for 47 outcome parameters from 13 oculomotor and reaction time tests. Sample sizes and age ranges varied across outcome parameters depending on the availability of reference values for RI calculations. The sample sizes used to calculate RIs ranged from 51 to 69. The age of SMVs included in each RI ranged from 19 to 61 years with mean ages ranging from 37 to 39 years. Similarities/differences between the RIs in the present study and those in previously published research are highly dependent on the outcome parameter; however, in general, the RIs in the present study tended to be somewhat wider.Conclusion The RIs provided in this paper can serve as comparisons for clinicians and scientists who are utilizing these oculomotor and reaction time testing paradigms in similar cohorts of patients or research participants.
The progressive integration of renewable energy resources in the modern power grid can result in unsatisfactory frequency responses. To address this problem, wind turbine generators (WTGs), in particular, can be employed to support the power grid. Most works, however, only consider a simple step disturbance. In this paper, a new class of worst-case disturbances is introduced and their nefarious impact on renewable-penetrated power systems is investigated. The worst-case disturbances are derived using optimal control theory. More importantly, the proposed mechanism allows to determine the reaction time to trigger supportive control actions of WTGs to ensure satisfactory frequency response. Numerical results are provided and the effects of the worst-case disturbance on the reaction time are presented.
Highlights: • Disc-like layered cobalt hydroxide microparticles were synthesized on reduced graphene oxide using one-pot hydrothermal method. • An enhanced dielectric constant of 7.19 × 10{sup 6} with a capacitance of 2.44 × 10{sup −6} F was achieved at 100 Hz frequency. • A leakage current of a few mA was produced in the composites that find potential applications in high-k gate dielectrics. - Abstract: Reduced graphene oxide (RGO)–cobalt hydroxide [Co(OH){sub 2}] composite was synthesized using one-pot hydrothermal method. The frequency-dependent dielectric properties and leakage conduction mechanism were studied for the composite. Samples were made with different reaction times of 2, 4, 6 and 12 h for the same concentration of graphene oxide and cobalt nitrate at constant temperature and pH. A high dielectric constant of 7.19 × 10{sup 6} with a capacitance of 2.45 × 10{sup −6} F was achieved for a reaction time of 2 h, at 100 Hz frequency and 27 °C temperature. One order decrement in the dielectric constant (10{sup 5}) was found with an increase in time starting from 4 to 12 h. The leakage current characteristics revealed Schottky barrier-type conduction mechanism in the composites. Thus, RGO-Co(OH){sub 2} composite with a high dielectric constant, microcapacitance and large leakage current could be regarded as a potential high-k candidate, which has its application as a gate dielectric material in the fabrication of metal oxide semiconductor field effect transistor.
Abstract Background Cognitive function and physical function are important predictors of mortality. Aim To investigate whether or not reaction time (RT) as a cognitive function and grip strength (GS) as a physical function were associated, alone or in combination, with mortality from heart disease or stroke. Methods The subjects included 4901 Adult Health Study participants in Hiroshima who had undergone RT and GS measurements, were 35–74 years old at baseline (1970–1972) and were followed until the end of 2007. Results After adjustment for other potential risk factors, RT was positively and GS was negatively associated with mortality from both heart disease and stroke. These associations were persistent in the model when adjusting simultaneously for RT, GS and other factors, but hazard ratios were attenuated. When we evaluated the associations by baseline age and gender, we found the greater hazard ratios for RT in the younger cohort, but no clear modification by age for GS. The interaction between RT and GS was statistically significant ( P = 0.012) for stroke mortality. In the stratified analyses divided using the age‐specific median value of RT or GS, the estimated hazard ratio of stroke mortality for RT was significant in participants with weak or strong GS but greater in the former, and for GS, it was only significant in participants with slow RT. Conclusion RT and GS, alone and in combination, predicted heart disease and stroke mortalities. Interventions for both cognitive function and physical function may be beneficial for the prevention of cardiovascular disease mortality.
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The sodium-manganese-iron phosphate Na{sub 2}Mn{sub 1.5}Fe{sub 1.5}(PO{sub 4}){sub 3} (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na{sup +} and presence of vacancies in A(2)’, Na{sup +} and small amounts of Mn{sup 2+} in A(1), Mn{sup 2+} in M(1), 0.5 Mn{sup 2+} and Fe cations (Mn{sup 2+},Fe{sup 2+} and Fe{sup 3+}) in M(2), leading to the structural formula Na{sub 2}Mn(Mn{sub 0.5}Fe{sub 1.5})(PO{sub 4}){sub 3}. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 h at 220 °C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220 °C for 6 h. When the reaction time was increased from 6 to 12, 24 and 48 h, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mA h g{sup −1} for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99% during 50 cycles. - Graphical abstract: SEM micrographs (left) and evolution of the discharge on cycling with increasing rates from C/15 to 4 C (right) of NMFP material prepared by hydrothermal synthesis at 220 °C at indicated time. Display Omitted - Highlights: • One-step hydrothermal method was used to prepare sodium manganese iron phosphate NMFP. • 3D-NMFP dandelion sphere-like particles were obtained at 220 °C after 6 h. • Increasing reaction time leads to the enhancement of the crystallinity and crystal stabilility of NMFP. • The growth of the particle size and change of morphology are correlated to the reaction time. • EC performance of NMFP powders were greatly affected by the synthesis conditions.
The initiation of aluminized fluorinated acrylic (AlFA) nanocomposites during modified Taylor impact tests was investigated. Samples were impacted against a steel or sapphire anvil at a nominal velocity of 150 m/s. A framing camera was used to capture head-on and side-profile impact images for the sapphire window and steel plate rigid anvils, respectively. Correlations were drawn between both experimental setups to determine the initiation locations and reaction times. Reactions were found to initiate at an intermediate radius on the impact face of the pellet at a time near full compaction. From simulations, the highest strains and temperatures were found at radii similar to those observed in experiments at the time of ignition. Off-normal impacts produced higher localized straining and temperatures on one-half of the pellet. As a result, the copper projectile, used for delivery, was revealed to aid in a shear assisted reaction by helping to drive the pellet material outward as the projectile deformed radially.
Abstract The syntheses of FeS 2 and Fe 3 S 4 nanomaterials were optimized using a novel facile, surfactant-free, and microwave-assisted, one-pot synthesis method, run under ambient and reasonably mild reaction conditions. Synthetic parameters, such as metal precursor salt identity, reaction time, reaction temperature, metal:sulfur molar ratios, and solvent combinations, were all systematically investigated and optimized. A series of FeS 2 (pyrite) samples was initially fabricated using thioacetamide (TAA) as the sulfur precursor to generate a distinctive, uniform octahedra-based morphology. Switching the sulfur precursor from TAA to L-cysteine resulted in a corresponding transformation in not only chemical composition from FeS 2 to an iron thiospinel structure, Fe 3 S 4 (otherwise known as greigite), but also an associated morphological evolution from octahedra to nanosheet aggregates. The study of these materials has enabled crucial insights into the formation mechanisms of these materials under a relatively non-conventional microwave-assisted setting. Furthermore, in separate experiments, multi-walled carbon nanotubes (MWNTs) and graphene were added in with underlying metal sulfide species to create conductive Fe–S/MWNT composites and Fe–S/graphene composites, respectively. The method of addition of either MWNTs or graphene was also explored, wherein an ‘ ex-situ ’ synthetic procedure was found to be the least disruptive means of attachment and immobilization onto iron sulfide co-reagents as a means of preserving the latter’s inherent composition and morphology. The redox acidity for the parent material and associated composites demonstrates the utility of our as-developed synthetic methods for creating motifs relevant for electrochemical applications, such as energy storage.
We comment the fractional space–time reaction–convection–diffusion defined by Grünwald–Letnikov, Riesz and Riesz–Feller fractional derivatives. We find the explicit travelling wave solution, using the similarity reduction. We plot its graphics to illustrate the anomalous behavior and investigate its properties associated with memory and distance effects.
Here, the conversion of furfuryl alcohol (FA) and selectivity towards dimers (C 9 -C 10 ) and trimers (C 14 -C 15 ) were investigated over molybdenum oxide (MoO 3 ) catalyst. It was observed that FA conversion increased as an increase of reaction time. However, longer reaction time tended to limit the selectivity to dimers and trimers. Characterization data obtained from XRD, Raman, and XPS showed that after the reaction the terminal Mo=O bond was elongated and the oxidation state was changed from Mo 6+ to Mo 5+ . This was likely caused by the delocalization of extra electron to the Mo center during the activation of FA on MoO 3 surface, instead of the formation of oxygen vacancy. After a proper regeneration process, the structure distortion caused by the elongation of Mo=O bond was fully restored, however, the oxidation state were only restored to Mo 5+ / 6+ . Finally, recyclability test using regenerated MoO 3 indicates Mo 5+ / 6+ can be as active as Mo 6+ .
Increasing ion molecule reaction times for ambient ionization techniques can increase sensitivity of detection. Longer reaction times result in an increase in analyte signal relative to the reactant ion signal, however with a subsequent decrease in the total ion intensity. This loss in the total number of ions reaching the detector limits the extent to which increased reaction time can improve detection in practical applications. In this study ion loss was measured using either electric fields or gas flow to control ion transit time. Ion transit times ranged from 40 ms to 8s, which resulted in ion densities ranging from 5 x 10 6 to 2 x 10 4 ions/cm 3 , respectively. These results provide insights into practical reaction time limitations or experimental boundaries when exploring sensitivity enhancements in ambient ionization. When exploring longer reaction times with an atmospheric flow tube coupled to a mass spectrometer (AFT-MS), an additional corona discharge ionization source of the same polarity was added in an attempt to increase total ion signal, but no improvement in signal was observed. This observation suggested that there was a maximum ion density being reached by the corona discharge that could not be increased by adding more of the same polarity ions. A hypothesis was that intermingling both polarities of ions would reduce ion loss and increase the measured ion signal. When two corona discharge sources—one each of positive and negative polarity—were used simultaneously in an AFT-MS, the total ion signal of either polarity measured by the MS was approximately double the current from a single corona discharge source. An increase in the negative ion signal was also observed when ~10 parts-per-trillion vapor levels of an explosive (RDX) were introduced. In this case both the nitrate reactant ions and the RDX signal more than doubled with the addition of a corona discharge source producing positive ions. When intermingling positive and negative ions, an increase in ion current was also observed when the AFT was coupled directly to a Faraday detector or to an ion mobility spectrometer. This was the first demonstration of interfacing the AFT to an IMS. The observations and developments from this work will help in creating more portable instruments with improved sensitivity for detection of chemicals.
Abstract Valorization of humins, the polymeric byproducts formed during the acid‐catalyzed production of HMF (5‐hydroxymethylfurfural) or furfural, is necessary to improve process economics and make biorefineries viable. We report the one‐step catalytic hydrotreatment of humins in methanol to humin oil containing fully or partially deoxygenated compounds. First, we compare four commercial noble‐metal catalysts (Ru/C, Rh/C, Pt/C, and Pd/C). Aromatic hydrocarbons, phenols, and esters are the main products detected by GC. Rh/C achieves the best GC‐detectable oil yield and 75 % humins conversion in 3 h at 400 °C, 30 bar H 2 , and a catalyst‐to‐humins mass ratio of 1:10. High H 2 pressures and intermediate temperatures, reaction times, and catalyst loadings enhance GC‐detectable oil yields. In contrast, high temperatures and long reaction times enhance gasification. Aromatics and phenols are found at high temperatures and long reaction times, whereas esters are the major species at short reaction times and high catalyst loading. 13 C‐isotopic labeling studies confirm, for the first time, that methanol participates in the alkylation and esterification reactions to form aromatic, phenolic and ester products. The reactivity in isopropanol is also discussed.
In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlled by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.