Reaction Velocity Research Articles

Mitochondrial morphology and function varies across diaphragm muscle fiber types

In diaphragm muscle (DIAm), type I and IIa fibers are recruited to accomplish breathing, while type IIx/IIb fibers are recruited only during expulsive/straining behaviors. Thus, type I and IIa DIAm fibers are much more active (duty cycle of ∼40 %) than type IIx/IIb fibers (duty cycle of <1%), which we hypothesized underlies intrinsic differences in mitochondrial structure and function. MitoTracker Green labeled mitochondria were imaged in 3-D using confocal microscopy. Mitochondrial volume density (MVD, per muscle fiber volume) was higher, and mitochondria were more filamentous in type I and IIa DIAm compared to type IIx/IIb fibers. The maximum velocity of the succinate dehydrogenase reaction (SDHmax), measured using a quantitative histochemical technique was found to be higher in type I and IIa DIAm fibers compared to type IIx/IIb fibers with and without normalizing for MVD. These results are consistent with fiber type differences in the intrinsic structural and functional properties of DIAm fibers and closely match differences in energetic demands.

Running power: lab based vs. portable devices measurements and its relationship with aerobic power

ABSTRACT In recent years, different companies have developed devices that estimate “running power”. The main objective of this paper is to evaluate the effect of running speed on aerobic and running powers measured using force plates and by different devices. The second objective is to evaluate the relationship between aerobic power and running powers measured using force plates and by different devices. We enrolled 11 subjects in the study, they performed 5-min running trials at 2.22, 2.78, 3.33, 3.89 and 4.44 m/s respectively on a force-measuring treadmill while we collected metabolic data. We calculated running power as the dot product of ground reaction force and velocity of the centre of mass and compared it to the running power estimates of three devices: Skillrun (Technogym), Stryd Summit Powermeter (Stryd) and Garmin HRM-Run (Garmin). We found statistically significant linear correlations with running powers measured by all devices and running speed. Although absolute running power measurements were different among devices, an increase of 1 m/s in running speed translated to an increase of 0.944 W/kg in running power (p < 0.001). We found statistically significant linear correlations with running powers measured by all devices and aerobic power, in particular: as aerobic power increases by 1 W/kg, running power increases by 0.218 W/kg for all devices (p < 0.001). For level treadmill running, across speeds, running power measured by commercially available devices reflects force-based measurements and it can be a valuable metric, providing quasi real-time feedback during training sessions and competitions. Highlights We evaluated the effect of running speed on aerobic and running powers measured using force plates and by different devices. We also compared the relationship between aerobic power and running powers measured using force plates and by different devices. We found statistically significant linear correlations with running powers measured by all devices and aerobic power, in particular: as aerobic power increases by 1 W/kg, running power increases by 0.218 W/kg for all devices. For level treadmill running, across speeds, running power measured by commercially available devices reflects force-based measurements and it can be a valuable metric, providing quasi real-time feedback during training sessions and competitions.

Molecular mechanisms and biochemical analysis of fluorene degradation by the Pseudomonas sp. SMT-1 strain.

Fluorene is a harmful organic toxicant extensively disseminated in the water and dry land ecosystem. Its toxicity and ubiquitous presence pose issues concerning its biodegradation. Characterization of the molecular mechanisms of fluorene degradation, detection of metabolites, and appraisal of its viability in toxicant removal by the SMT-1 Pseudomonas sp. strain are the main purposes of this study. In this work, the catabolic intermediates were identified from resting cell reactions of the SMT-1 strain as well as the involved catabolic pathway of fluorene. Based on liquid chromatography mass spectrometry analysis, the identified intermediates were 9-fluorenone; 3,4-dihydroxy-9-fluorenone; phthalate and protocatechuic acid. The specific primers were designed to amplify the fluorene-degrading 4921 dioxygenase gene segment from the SMT-1 Pseudomonas sp. strain. The 4921 dioxygenase gene was expressed, purified and characterized. The apparent K m and V max values were 25.99µMmin-1 and 0.77 U mg-1, respectively. The enzyme was most active at pH 7.5 and 25°C in Tris-HCl buffer and was identified by measuring the initial reaction velocity for 1min. Effect of metal salts on enzyme activity was accessed to see the impact on protein stability. Most of the analyzed metal salts inhibited enzyme activity to different degrees, and exhibited very low activity in the presence of FeCl3. Understanding the physiological, metabolic pathway and molecular mechanism of fluorene degradation is an important factor in increasing significant information of this biological process. This strain may serve as a potential candidate for further use in the bioremediation process to treat organic toxicant contaminated sites.

Conoidecyclics A-C from marine macroalga Turbinaria conoides: Newly described natural macrolides with prospective bioactive properties

Intertidal marine brown alga Turbinaria conoides (J.Agardh) Kützing (family Sargassaceae) is considered as one of the largely abundant species, available in the coastal zones of the Indian subcontinent. Bioactivity-guided chromatographic fractionation of the organic extract of T. conoides resulted in three previously undescribed macrocyclic lactone homologues, named as conoidecyclics A-C. Conoidecyclic A displayed greater attenuation potential against cyclooxygenase-2 (IC50 1.75 mM) and 5-lipoxygenase (IC50 4.24 mM) in comparison with other analogues. Conoidecyclic A exhibited higher attenuation potential against 5-lipoxygenase than that displayed by an anti-inflammatory agent, ibuprofen (IC50 4.51 mM). The higher selectivity index of conoidecyclic A (1.79) recognized its selective attenuation potential against the inducible cyclooxygenase-2 enzyme. Inhibition potential of conoidecyclic A against angiotensin converting enzyme-I (IC50 1.23 mM) and protein tyrosine phosphatase-1B (IC50 1.39 mM) were non-competitive, as deduced by kinetic studies. In-silico molecular modeling study of conoidecyclic A with the allosteric sites of the targeted enzymes exhibited least binding energy of −14.51 to −11.27 kcal mol−1 compared to those exhibited by other studied macrolide homologues. Reaction kinetic studies of conoidecyclic A coupled with lesser apparent Vmax inferred that it could efficiently bind with the allosteric site of targeted enzymes in a non-competitive manner to diminish the reaction velocity resulting in enzyme inhibition. Drug-likeness and predictive pharmacokinetic parameters of conoidecyclic A exhibited an acceptable oral bioavailability. These reports inferred that conoidecyclic A encompassing pentacosa macrocyclic moiety could be a promising therapeutic lead to inhibit the enzymes related to the development and progression of pathological conditions leading to inflammation, hypertension and type-2 diabetes.

The free radical mechanism of electromagnetic field affecting explosion of premixed methane

To study the mechanism of the electromagnetic field influences flammable gas explosions, 9.5% methane-air explosion tests were carried out in a closed transparent pipe and the effect of the electromagnetic field on the free radicals was analyzed through COMSOL Multi-physics. The relationship between explosion pressure, explosion product composition and its concentration and movement of key free radicals was analyzed from the results of experiment and numerical simulation. In the experiment, the reactions between the reactants and the free radicals were intensified such that the mean overpressure increases by 49.76%, the time of forming in similar flame shape was advanced by 15 ms, 39 ms and 99 ms respectively at the same location and the explosion reaction proceeded violently, and residual methane decreased by 24.57% and carbon monoxide increased by 55.67% in the product components and the generation of other hydrocarbons also decrease. From simulation, the electromagnetic field accelerated the movement of paramagnetic free radicals, which increased the effective collisions of the reaction, and promoted the chain reaction velocity. Accordingly, in places where there is a danger of flammable gas explosions, electromagnetic fields should be avoided.

Immobilized Crosslinked Pectinase Preparation on Porous ZSM-5 Zeolites as Reusable Biocatalysts for Ultra-Efficient Hydrolysis of β-Glycosidic Bonds.

In this study, we immobilized pectinase preparation on porous zeolite ZSM-5 as an enzyme carrier. We realized this immobilized enzyme catalyst, pectinase preparation@ZSM-5, via a simple combined strategy involving the van der Waals adsorption of pectinase preparation followed by crosslinking of the adsorbed pectinase preparation with glutaraldehyde over ZSM-5. Conformal pectinase preparation coverage of various ZSM-5 supports was achieved for the as-prepared pectinase preparation@ZSM-5. The porous pectinase preparation@ZSM-5 catalyst exhibited ultra-efficient biocatalytic activity for hydrolyzing the β-glycosidic bonds in the model substrate 4-nitrophenyl β-D-glucopyranoside, with a broad operating temperature range, high thermal stability, and excellent reusability. The relative activity of pectinase preparation@ZSM-5 at a high temperature (70 °C) was nine times higher than that of free pectinase preparation. Using thermal inactivation kinetic analysis based on the Arrhenius law, pectinase preparation@ZSM-5 showed higher activation energy for denaturation (315 kJ mol−1) and a longer half-life (62 min−1) than free pectinase preparation. Moreover, a Michaelis–Menten enzyme kinetic analysis indicated a higher maximal reaction velocity for pectinase preparation@ZSM-5 (0.22 µmol mg−1 min−1). This enhanced reactivity was attributed to the microstructure of the immobilized pectinase preparation@ZSM-5, which offered a heterogeneous reaction system that decreased the substrate–pectinase preparation binding affinity and modulated the kinetic characteristics of the enzyme. Additionally, pectinase preparation@ZSM-5 showed the best ethanol tolerance among all the reported pectinase preparation-immobilized catalysts, and an activity 247% higher than that of free pectinase preparation at a 10% (v/v) ethanol concentration was measured. Furthermore, pectinase preparation@ZSM-5 exhibited potential for practical engineering applications, promoting the hydrolysis of β-glycosidic bonds in baicalin to convert it into baicalein. This was achieved with a 98% conversion rate, i.e., 320% higher than that of the free enzyme.

Essential moieties of myricetins, quercetins and catechins for binding and inhibitory activity against α-Glucosidase

α-Glucosidase inhibition of 11 flavonoids, including myricetins, quercetins and catechins were studied through initial reaction velocity, IC50 value, inhibition kinetics, fluorescence quenching and molecular docking. It was found that C4 = O, C2 = C3, 3-OH and 5′-OH were essential moieties for α-glucosidase inhibition of myricetin that was shown with the highest inhibitory activity. The trans-conformational catechins was shown with stronger inhibition effects than the cis-conformational ones. Further, gallocatechin was an uncompetitive inhibitor, while myricetin, myricetrin, quercetin and catechin were competitive ones. 3-OH and 5′-OH promoted myricetin to bind with the enzyme active site through hydrogen bondings. The presence of C4 = O and C2 = C3 increased electron delocalization in ring A-C for myricetin and quercetin, and this enhanced stability of π-conjugations with aromatic residues of amino acids. However, 5′-OH decreased the quenching effects because it limited π-conjugations of ring B with key fluorescent residues. Notably, for same flavonoid sort, the constants that indicate binding affinity of flavonoids to α-glucosidase, including reciprocal of competitive inhibition constant, fluorescence quenching constant and binding energy followed same order as the inhibitory activity, indicating that α-glucosidase inhibition of the flavonoids resulted from binding interactions between them, and that the methods above can be combined reasonably to characterize flavonoid-enzyme binding interactions.

Defect-rich and ultrathin nitrogen-doped carbon nanosheets with enhanced peroxidase-like activity for the detection of urease activity and fluoride ion

Although carbon nanozymes have attracted great interest due to their good biocompatibility, low cost, and high stability, designing high-active carbon nanozymes still faces great challenges. Herein, ultrathin nitrogen-doped carbon nanosheets with rich defects (d-NC) were prepared through a high-temperature annealing process, using potassium chloride and ammonium chloride as templates. Owing to the large specific surface area, rich defects and the high exposure of active sites, the proposed d-NC nanozymes exhibited excellent peroxidase-like activity. The d-NC nanozymes possess maximal reaction velocity and their specific activity is 9.4-fold higher than that of nitrogen-doped carbon nanozymes, indicating that the induced defects can boost the catalytic performance. Benefited from the good peroxidase-like activities of d-NC nanozymes, the colorimetric sensing platforms were constructed for the detection of urease activity and fluoride ion, exhibiting satisfactory stability and selectivity. This study not only offers a way to synthesize carbon nanozymes with improved enzyme-like activities but also broadens their applications in colorimetric biosensing.

Effect of resin staging on frontal polymerization of dicyclopentadiene

AbstractIn thermal frontal polymerization (FP), ambient temperature and staging conditions highly affect the resin behavior and front properties. This study describes the effect of staging conditions and resin reactivity on frontal ring opening metathesis polymerization of dicyclopentadiene in presence of phosphite‐inhibited second‐generation Grubbs catalyst. An experimental setup is designed to characterize and understand the effect of inhibitor concentration, incubation time, and incubation temperature on front velocity, activation time, and front temperature of the FP reaction. The results reveal that front properties are influenced by various factors, including available energy density of resin, stability of catalyst‐inhibitor complex, resin temperature, and resin viscosity. An increase in staging temperature results in lower pot lives but faster gelation process and activation of FP reaction. Additionally, increasing the inhibitor concentration leads to slower fronts, higher activation times, and longer pot lives. The results of this study can be extended to other FP systems and can be used in design of new manufacturing processes and applications using FP.

Microfabricated potentiometric sensor for personalized methacholine challenge tests during the COVID-19 pandemic

The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary function labs or doctors’ offices. Methacholine (MCH) acts by inducing airway tightening/bronchoconstriction, and more importantly, MCH is hydrolyzed by cholinesterase enzyme (ChE). Recently, the American Thoracic Society raised concerns about pulmonary function testing during the COVID-19 pandemic due to recently reported correlation between cholinesterase and COVID-19 pneumonia severity/mortality, and it was shown that cholinesterase levels are reduced in the acute phase of severe COVID-19 pneumonia. This work describes the microfabrication of potentiometric sensors using copper as the substrate and chemically polymerized graphene nanocomposites as the transducing layer for tracking the kinetics of MCH enzymatic degradation in real blood samples. The in-vitro estimation of the characteristic parameters of the MCH metabolism [Michaelis–Menten constant (Km) and reaction velocity (Vmax)] were found to be 241.041 μM and 56.8 μM/min, respectively. The proposed sensor is designed to be used as a companion diagnostic device that can (i) answer questions about patient eligibility to perform methacholine challenge tests, (ii) individualize/personalize medical dosing of methacholine, (iii) provide portable and inexpensive devices allowing automated readouts without the need for operator intervention (iv) recommend therapeutic interventions including intensive care during early stages and reflecting the disease state of COVID-19 pneumonia. We hope that this methacholine electrochemical sensor will help in assaying ChE activity in a “timely” manner and predict the severity and prognosis of COVID-19 to improve treatment outcomes and decrease mortality.

Synergistic effects in Mn-Co mixed oxide supported on cordierite honeycomb for catalytic deep oxidation of VOCs

A series of Co-Mn mixed oxide catalyst supported on a cordierite monolith was facilely synthesized by ultrasonic impregnation. Its catalytic performance was evaluated in the combustion of toluene, ethyl acetate and its mixture. It was observed that with incorporating Mn into Co3O4, the formation of solid solution with spinel structure could significantly improve the catalytic activity of pure phase Co3O4. And the monolithic Co0.67Mn0.33Ox catalyst showed the best catalytic performance in the catalytic oxidation of toluene and ethyl acetate which could be completely oxidized at 220 and 180°C respectively under the reaction velocity (WHSV) about 45,000 mL/(g•hr) and pollutant concentration of 500 ppmV. The total conversion temperature of the VOCs mixture was at 230°C (500 ppmV toluene and 500 ppmV ethyl acetate) and determined by the temperature at which the most difficult molecule was oxidized. The excellent catalytic performance of monolithic Co0.67Mn0.33Ox was attributed to the higher content of Mn3+, Co3+, surface adsorbed oxygen and better redox ability. The prepared catalyst showed the good mechanical stability, reaction stability, and good adaptability to different reaction conditions.

Kinetic Studies of Aspergillus ficuum Tannase Enzyme and its Application in Detannification of Grape Juice

This investigation was carried out to study the characterization and kinetics of the partially purified Aspergillus ficuum tannase enzyme for commercial scale application in the clarification and detannification of juices like grape. pH, temperature and optimum substrate concentration were determined for the tannase enzyme activity from Aspergillus ficuum. Also, the Crude and partial purified enzyme were tested for detannification grape juice quality characteristics. Results evidenced that it was found that the optimum partial purified tannase parameters were: temperature 50 oC, PH 5.5 and substrate concentration 1.6% as a tannic acidwith 6.155 specific activities of partial purified tannase enzyme with 225.46% relative activity higher than its control. The tannase enzyme showed a higher temperature and lower pH optima than the soluble enzyme and showed 81.61% and 66.36 % tannin removal from grape juice by crude enzyme and partial purified enzyme treatment, respectively at 37 oC, which has not been reported earlier. Also, maximum velocity of reaction (Vmax) and Michaeli’s constant (Km) values were 0.72 and 1.45 for partially purified tannase enzyme activity, respectively. Overall the quality of grape juice was better in partial pure tannase treated juice compared with untreated and crude enzyme treated juice. The present study exposed thatthis enzyme could demonstrate a valuable tool for a number of biotechnological applications. Also, the application of this enzyme on juice clarification also states that it can be employed in fruit juice processing for removal of tannin efficiently.

(Invited) On the Effective Design of Electrochemical Interfaces for Solar Production of Fuels

Extensive research has been conducted on man-made systems for the solar production of fuels in which many different chemical and physical constructs and prototypes have been assembled to demonstrate the possibility of creating fuels from sunlight. These efforts comprise a broad array of chemical and electrochemical work that originates in the Fujishima and Honda work on photoelectrochemical water splitting and has moved on to molecular-based catalysts for water splitting as well as designed nanostructures of semiconductors for light absorption and charge separation.This presentation examines how the mechanistic design of these systems for solar fuels production constrain and define the chemistry and electrochemistry of the solid and molecular components required for effective operation. It will also identify alternative approaches that show promise. The discussion will begin with design analyses of the photosynthetic system for carbon fixation and man-made photosystems for the oxidation of water as a sacrificial electron donor for fuels production. It will be shown how the kinetics inherent in their operational design imposes demands upon the photosystem components, in particular the catalyst TOF and TON figures. With this collection of designs, full structures for water or carbon dioxide reduction can be composed and consequent demands upon catalysts can be quantified.While many research systems for solar photoconversion are given as examples of “artificial photosynthesis,” few actually take full advantage of the important design principles that underlie the effectiveness of photosynthesis as a means of transducing solar energy into the biochemistry of a life form. A tracing of the flow of energy and charge through the photosynthetic reaction centers and then to RuBisCO for CO2 fixation reveals the significance of impedance matching at various coupling points in the system. A direct coupling of Photosystem II with the oxygen evolving catalyst is evident as is indirect coupling at other points where protons and redox agents are produced and their diffusion creates a Nernstian concentration potential at distant locations to initiate further reaction. These types of coupling are of consequence in man-made systems.The oxidation of water provides the electrons and protons for solar driven reduction reactions, whether it be natural or artificial. Nature has its own oxygen evolving complex in photosynthesis to effect this reaction and there are many man-made structures that have been assembled and studied to oxidize water as well. A kinetic design of the natural system will be drawn in this presentation that will be compared with the kinetic designs of representative artificial systems and a critique will be made. These include semiconductor photoelectrolysis of water, dye sensitized electrochemical water oxidation, molecular water oxidation catalysts, and particulate and nanostructured systems for water splitting. The relationship between the kinetic design of the system and the component solids, catalysts and associated species will be shown.The catalytic reduction of CO2 or water to a fuel are wide spread and dynamic areas of research. Whereas the electrochemistry of water reduction to hydrogen has long been an object of study, the catalysis of CO2 reduction is much less developed. Molecular catalysts are being sought for this role as are interfacial metal deposits with both being accompanied by theoretical backing. Given the recognition and analysis of the various designs identified in this discussion, a more effective effort can be made in the development of photosystems for production of these fuels. They can help define not only the form of the catalyst, be it solid or molecular, but also its required reaction velocity and durability.

Hydrolysis of Lignocellulosic Biomass in Hot-Compressed Water with Supercritical Carbon Dioxide.

This study investigated the decomposition behavior of bamboo under hydrothermal and hydrolysis conditions with H2O/CO2 in a semicontinuous-flow reactor at 9.8 MPa. At 255 °C, with and without CO2, xylan in bamboo completely decomposed into xylo-oligosaccharide (XOD). The yield of glucan degradation products with CO2 was significantly higher compared with that under the hydrothermal reaction (25.7 vs 14.9 wt %, respectively). The reaction rate of glucan decomposition with CO2 was slightly higher than the rate of hydrothermal reaction (kH2O/CO2/kH2O = 1.3). Increasing the fluid velocity of the hydrothermal reaction (3–10 mL/min) significantly accelerated the solubilization rate, but the ultimate yield of the soluble fraction was unchanged. The ultimate yield of the soluble fraction was slightly affected by physical effects. Hydrolysis with CO2 under severe conditions exhibited effective degradation of glucan. The catalytic activity of the H2O/CO2 system under hydrolysis can be explained by the system’s chemical effect.

Temperature effect in physicochemical and bioactive behavior of biogenic hydroxyapatite obtained from porcine bones

Biogenic hydroxyapatite (BHAp) is a widely used material in the biomedical area due to its similarities with the bone tissue mineral phase. Several works have been spotlighted on the thermal behavior of bone. However, little research has focused on determining the influence of calcination temperature in the physicochemical and bioactive properties of BHAp. In this work, a study of the physicochemical properties’ changes and bioactive response of BHAp produced from porcine femur bones using calcination temperatures between 900 to 1200 °C was conducted. The samples’ structural, morphological, and compositional changes were determined using XRD, SEM, and FTIR techniques. XRD results identified three temperature ranges, in which there are structural changes in BHAp samples and the presence of additional phases. Moreover, FTIR results corroborated that B-type substitution is promoted by increasing the heat treatment temperature. Likewise, samples were immersed in a simulated biological fluid (SBF), following the methodology described by Kokubo and using ISO 23317:2014 standard, for 3 and 7 days. FTIR and SEM results determined that the highest reaction velocity was reached for samples above 1000 °C, due to intensity increasing of phosphate and carbonate bands and bone-like apatite morphologies, compared to other temperatures evaluated.

An SIR-type epidemiological model that integrates social distancing as a dynamic law based on point prevalence and socio-behavioral factors

Modeling human behavior within mathematical models of infectious diseases is a key component to understand and control disease spread. We present a mathematical compartmental model of Susceptible–Infectious–Removed to compare the infected curves given by four different functional forms describing the transmission rate. These depend on the distance that individuals keep on average to others in their daily lives. We assume that this distance varies according to the balance between two opposite thrives: the self-protecting reaction of individuals upon the presence of disease to increase social distancing and their necessity to return to a culturally dependent natural social distance that occurs in the absence of disease. We present simulations to compare results for different society types on point prevalence, the peak size of a first epidemic outbreak and the time of occurrence of that peak, for four different transmission rate functional forms and parameters of interest related to distancing behavior, such as: the reaction velocity of a society to change social distance during an epidemic. We observe the vulnerability to disease spread of close contact societies, and also show that certain social distancing behavior may provoke a small peak of a first epidemic outbreak, but at the expense of it occurring early after the epidemic onset, observing differences in this regard between society types. We also discuss the appearance of temporal oscillations of the four different transmission rates, their differences, and how this oscillatory behavior is impacted through social distancing; breaking the unimodality of the actives-curve produced by the classical SIR-model.

A Kinetic Study in Fermentation of Cocoa Pod Husk using Zymomonas Mobilis

In many years, bioethanol research has been an outstanding topic because of renewable energy issue. The aim of this research is focused on utilization of cocoa pod husk as a feedstock for bioethanol production through fermentation using Z. mobilis. Moreover, the kinetic model of cocoa pod husk fermentation using Z. mobilis as a microorganism was also preformed in this study. Fermentation of cocoa pod husk was carried out at room temperature for 0, 2, 4, 6, and 8 days of reaction. The bacteria were also varied with 8%, 10%, 12%, 14%, and 16% (v/v) of concentration towards the substrate mixture. The kinetic model was conducted by Michaelis – Menten equation followed by Eadie-Hofstee plot and batch kinetic data plot for its fitting parameter technique. The result of this study indicates that the slow reaction has occurred regarding the low value of conversion and small value of maximum reaction velocity. The highest conversion was achieved on the 8th day with 14% (v/v) of bacteria concentration that is 10.65%. The maximum velocity of reaction for 16% (v/v) of bacteria addition was obtained at approximately 0.0017 mol/L.hour.

Simultaneously enhanced reaction temperature and velocity of self-propagating high-temperature synthesis via Joule-heat induced multi-channel heat flow

Simultaneous enhancement of reaction temperature and velocity of self-propagating high-temperature synthesis is still a challenge. Here, we propose a general method based on the Joule-heat induced multi-channel heat flow to simultaneously increase the reaction temperature and velocity of self-propagating high-temperature synthesis. A designed surface structure induces multi-channel Joule-heat accumulation at the surface of reaction components and subsequently multi-channel heat flow during the self-propagating processes. Multi-channel heat flow leads to the formation of two combustion stages: the self-propagating process and the Joule-heat induced grain growth, leading to an enhancement of the maximum reaction temperature up to 67%. Meanwhile, multi-channel heat flow will reduce the propagation distance of the reaction wave and the heat conduction between heat flow channels will increase the temperature of the reaction components, in turn, resulting in an increase in the reaction velocity that is five times higher. We expect that our findings will pave the way for the future application of self-propagating high-temperature synthesis in industries.

Construction of the Core–Shell Tourmaline@ZnO Micro-nano Structure Towards the Highly Efficient Degradation of Organic Pollutants

In this research, unique Tourmaline@ZnO micro-nano structure were constructed by surface-coating using uniform precipitation, with tourmaline particles as the inner core and nano-zinc oxide as the outer layer. In order to explore the optimized preparation conditions towards the highly efficient degradation of organic pollutant, the preparative experiments were implemented based on the two most crucial processing parameters: growth temperature and dosage of tourmaline. The structure, morphology and surface analysis of as-prepared core–shell composites were systemically characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller and x-ray photoelectron spectroscopy measurements, then the optical and optoelectrical properties were tested by ultraviolet–visible spectroscopy, photoluminescence spectroscopy and electrochemical performance. The photocatalysis performances were evaluated by selecting methyl orange as the model dye under the irradiation of a xenon lamp. In the case of a growth temperature of 100°C and tourmaline introduction amount of 3 wt.%, the correlated investigations confirmed that the hybrid tourmaline@nano-ZnO product achieved the most efficient degradation efficiency of 90% and the fastest reaction velocity of 0.8889 h−1 respectively within 2 h, with an enhancement of 9% and 36% compared to pure ZnO (the degradation rate was 81% and reaction rate was 0.6521 h−1). The tourmaline core was confirmed to make important contributions to the growth morphology and degradation performance of ZnO-based photocatalytic materials. The introduction of tourmaline will play a key role in the properties modification of metal oxide.

Direct Measurement of Initial Rate of Enzyme Reaction by Electrokinetic Filtration Using a Hydrogel-plugged Capillary Device.

A novel electrokinetic filtration device using a plugged hydrogel was developed to directly measure the initial rate of enzyme reactions. In the proposed method, the enzyme reaction proceeded only for a short time when the substrate was passed through a thin layer of enzyme trapped by the hydrogel without any lag times for mixing and detection. In experimental conditions, alkaline phosphatase (enzyme) was filtrated at a cathodic-side interface of the plugged hydrogel by molecular sieving effect, providing the thin enzyme zone whose thickness was approximately 100 μm. When 4-methylumberiferyl phosphate (substrate) was electrokinetically introduced into the device after trapping the enzyme, 4-methylumberiferone (product) was generated by the enzyme reaction for only 1.26 s as the substrate passed through the trapped enzyme zone. As a result, the initial rate of the enzyme reaction could be directly calculated to 31.0 μM/s by simply dividing the concentration of the product by the tunable reaction time. Compared to the initial rate obtained by mixing the enzyme and substrate solutions, the value of the maximum velocity of the enzyme reaction was 30-fold larger than that in the mixing method due to the preconcentration of the enzyme by trapping. The Michaelis-Menten constant in the proposed method was 2.7-fold larger than that in the mixing method, suggesting the variation of changes in the equilibrium of complex formation under the experimental conditions.