Moment Of Reaction Research Articles

Photocatalytic Easy Recovery of Orthophosphates Contaminants in Water Using Amberlite‐732 Cationic‐Resin Exchanged by Ce3+and Ce3+‐Au3+ Species

AbstractThis report discusses the efficiency of photo‐recovery of orthophosphate anions in water under visible irradiation using materials containing amorphous carbon, ceria and gold‐ceria species. Catalysts were obtained by the exchange of Amberlite‐732 polymeric‐resin with isolated Ce(III) and co‐mixing of Ce(III)‐Au(III) cations. Syntheses were developed for molar ratios Ce(III)/3H+=100 and Au(III)‐Ce(III)/3H+=0.01. Solids were treated at 800 °C under Air or Ar atmosphere then characterized by: X‐ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy coupled to energy‐dispersive X‐ray spectroscopy (EDS), X‐ray photoemission spectroscopy (XPS) and UV‐visible spectroscopy. By XRD, non‐stoichiometric Ce2.658S4 sulfide and particles of metallic gold are identified in Ce‐Au‐Amb‐Ar and in the case of Ce‐Au‐Amb‐Air, mixture of CeO2 and Au0 is clearly observed. Moreover, XPS study of Ce3d emission spectra showed well resolved electronic states of the spin‐orbit Ce3d5/2 and Ce3d3/2 levels in the Ce4+ and Ce3+ oxidation states confirming coexistence of Ce(IV)/Ce(III). On the surfaces of both Ce‐Au‐Amb‐Air and Ce‐Au‐Amb‐Ar, XPS revealed metallic Au species. A certain amount of carbon, identified by EDS and XPS, corresponds to poorly ordered carbon formed by the resin decomposition during thermal treatments under Air and Ar. The UV‐vis spectroscopy was valuable to quantify the remaining PO43− anions in solution (at each moment of reaction) using “Molybdenum Blue” method. Photo‐recovery of orthophosphates under visible irradiation yields optimal trapping of ∼75 % of PO43− on Ce‐Au‐Amb‐Ar, attributed to a catalyst surface enrichment with Ce3+ species, which promoted structural oxygen vacancies.

Dynamics of nanoscale thin liquid films during coalescence and chemical reaction of droplets

The understanding of flow characteristics and interface structure evolution during the chemical reaction of droplets are important for many industrial processes. In this paper, qualitative observation and quantitative measurement are implemented at the region near the contact line of acetic acid and ammonium hydroxide droplets to study the flow field and interface evolution during the neutralization reaction of these testing fluids by an observation technique based on evanescent wave illumination. A three-dimensional sub-region method for characterizing the interface structure of the thin liquid film during droplet reaction is developed. The interface structures and velocity fields of the thin liquid films obtained by this method reveal that at the moment of reaction the mesoscopic interface structure deforms severely and the convex interfaces appear at the central regions due to the impact of the initial kinetic energy and the chemical reaction of droplets. Meanwhile, the reaction rate is found to decrease exponentially with the increase of height in the thin liquid film. The work provides valuable information for further understanding the mechanisms of formation and transport of the mesoscale interface structure during chemical reactions.

Design of Deep Learning Model for Task-Evoked fMRI Data Classification.

Machine learning methods have been successfully applied to neuroimaging signals, one of which is to decode specific task states from functional magnetic resonance imaging (fMRI) data. In this paper, we propose a model that simultaneously utilizes characteristics of both spatial and temporal sequential information of fMRI data with deep neural networks to classify the fMRI task states. We designed a convolution network module and a recurrent network module to extract the spatial and temporal features of fMRI data, respectively. In particular, we also add the attention mechanism to the recurrent network module, which more effectively highlights the brain activation state at the moment of reaction. We evaluated the model using task-evoked fMRI data from the Human Connectome Project (HCP) dataset, the classification accuracy got 94.31%, and the experimental results have shown that the model can effectively distinguish the brain states under different task stimuli.

Характеристики конічних підвісів з поздовжніми глухими мікроканавками постійної ширини і різним профілем по глибині

Gas bearings with longitudinal grooves are successfully used in high-speed spindle units of drilling and grinding machines, processing equipment for processing crystals and precision instruments. But a small viscosity and compression of gas requires a detailed study of all factors that affect their work. The reliability of gas bearings depends on the compliance of the calculated values of the lifting force, the moment of reaction and the rigidity of the working gas layer from the external load, and the economy — on the gas flow. Engineers and scientists constantly search for structures and methods for calculating gas bearings with maximum power characteristics with minimal gas consumption. This is achieved using external chokes, a combination of external and internal throttling of the gas flow. The use of gas bearings with longitudinal grooves is determined by the manufacturability of their manufacture and high reliability in operation. But bearings of this type are significantly inferior in their characteristics to bearings with pressure regulators outside the carrier gas layer with a relative bearing length of l £ 3. To improve the characteristics of bearings with longitudinal grooves, it is necessary to reduce costs and harmful circular flow of gas in the working gap from the section of increased pressure to the lower side. This is achieved by using variable profile grooves with a maximum depth of grooves in the compressed gas supply zone for working of gas bearings. The proposed application of stepped longitudinal micro-grooves and micro-grooves, the depth of which varies according to the linear law with the maximum depth at the line of pressure of compressed gas into the working gaps of the conical bearing, leads to an increase in the efficiency of Eε (Kε*/Q* ratio) of the use of tapered bearings in spindle units, devices and etc. from 13,9 to 16,8 % for α = 2° and from 1,2 to 16,5 % for α = 6° and reduces the radial displacement of the axis of the shaft with the coaxial with the body of the position by 17…27 % compared with the bearings with the micro-grooves constant depth (with the same external load), which increases the reliability of the work of the spindle units. The profile of longitudinal micro-grooves has an insignificant effect on the angular and axial stiffness of the bevel bearing and greatly affects the radial stiffness.

Crosslinkable deoxidizing hybrid adhesive of epoxy–diacid for electrical interconnections in semiconductor packaging

AbstractFor electrical interconnections in semiconductor packaging, epoxy‐based pastes have recently attracted considerable interest due to their excellent adhesion to various substrates and their reasonable electrical and mechanical properties, especially when combined with deoxidizing agents (to remove metallic oxides). Here, epoxy–diacid‐based hybrid pastes were examined to achieve a deoxidizing capability for eliminating Sn‐based solder oxides and adhesion between microchip and substrate as a one‐step process. Onset, exothermic peak and end temperatures of the reaction between epoxy and diacids were systematically probed using DSC, rheometry and Fourier transform infrared (FTIR) spectroscopy. The last moment of the adhesive reaction during heating substantially enhanced the thermal and mechanical properties of the epoxy–diacid adhesive despite the absence of exothermic enthalpy detected by DSC. The glass transition temperature (Tg) and Young's modulus gradually decreased as a function of aliphatic chain length of diacids except when the length was extremely short and voids were produced. Soldering (wetting) and deoxidizing capabilities of the hybrid adhesive were observed via optical microscopy and FTIR. The correlation between the reaction, Tg, conversion and viscosity was also investigated. Lastly, complete wetting and electrical interconnection with good mechanical robustness were achieved for a commercial chip/substrate set by flip‐chip bonding. © 2018 Society of Chemical Industry

Influence of gait speed on free vertical moment during walking

Free vertical moment (FVM) of ground reaction is recognized to be a meaningful indicator of torsional stress on the lower limbs when walking. The purpose of this study was to examine whether and how gait speed influences the FVM when walking. Fourteen young healthy adults performed a series of overground walking trials at three different speeds: low, preferred and fast. FVM was measured during the stance phase of the dominant leg using a force platform embedded in a 10 m-long walkway. Transverse plane kinematic parameters of the foot and pelvis were measured using a motion capture system. Results showed a significant decrease in peak abduction FVM (i.e., resisting internal foot rotation) and an increase in peak adduction FVM (i.e., resisting external foot rotation), together with an increase in gait speed. Concomitantly, we observed a decrease in the foot progression angle and an increase in the peak pelvis rotation velocity in the transverse plane with an increase in gait speed. A significant positive correlation was found between the pelvis rotation velocity and the peak adduction moment, suggesting that pelvis rotation influences the magnitude of adduction FVM. Furthermore, we also found significant correlations between the peak adduction FVM and both the step length and frequency, indicating that the alterations in FVM may be ascribed to changes in these two key variables of gait speed. These speed-related changes in FVM should be considered when this parameter is used in gait assessment, particularly when used as an index for rehabilitation and injury prevention.

Smoluchowski Reaction Kinetics for Reactions of Any Order

In 1917, Marian von Smoluchowski presented a simple mathematical description of diffusion-controlled reactions on the scale of individual molecules. His model postulated that a reaction would occur when two reactants were sufficiently close and, more specifically, presented a succinct relationship between the relative proximity of two reactants at the moment of reaction and the macroscopic reaction rate. Over the past century, the Smoluchowski reaction theory has been applied widely in the physical, chemical, environmental, and, more recently, biological sciences. Despite the widespread utility of the Smoluchowski theory, it only describes the rates of second order reactions and is inadequate for describing higher order reactions for which there is no equivalent method for theoretical investigation. In this paper, we derive a generalized Smoluchowski framework in which we define proximity in the context when more than two reactants are involved. We derive the relationship between the macroscopic reaction rate and the critical proximity at which a reaction occurs for higher order reactions. Using this theoretical framework and through numerical experiments, we explore various peculiar properties of multimolecular diffusion-controlled reactions which, due to there being no other numerical method of this nature, have not been previous reported.

Free moment patterns, transversal plane joint loading and injury risk in running

The free moment (FM) of ground reaction is applied by runners to the ground in order to control whole body angular momentum in the transversal plane of movement. The FM is a dominant component of l...

Parametric resonances in the two-to-one resonant beams on elastic foundation

The nonlinear vibration of the inextensional beam on the elastic foundation under parametric resonance and two-to-one internal resonance is investigated. Considering the inextensional condition and the second-order moment of the subgrade reaction, the extended Hamilton principle is applied to derive the motion equation of the beam on elastic foundation. Then the multimodal discretization and the method of multiple scales are used to obtain the modulation equations. The nonlinear response is examined by means of the frequency- and force–response curves. It is shown that the two-mode solution is born when the single-mode solution undergoes the pitchfork bifurcation. The shooting method and numerical simulations are applied to investigate the dynamic solutions. Particular attention is placed on the effects of the cut-off frequency on the nonlinear response.

Dynamic modeling of the finite-length beam on the elastic foundation

In civil engineering, the vibration problem of the beam on the elastic foundation plays an important role in the analysis of some soil-structure interaction problems. Considering the inextensional condition, the motion equation of the beam on the elastic foundation is derived via the Newtons method and Hamilton principle. Due to the second-order moment of the subgrade reaction, the equation of motion includes the quadratic nonlinearity. Moreover, the primary resonance of the beam on the elastic foundation is investigated, and the effect of the second-order moment on the nonlinear response is examined.

Three-to-One Resonant Responses of Inextensional Beams on the Elastic Foundation

The large amplitude vibrations of the inextensional beam resting on the elastic foundation under three-to-one internal resonance are investigated. The inextensional condition and multimodal discretization are used to obtain the equation of in-plane motion and modulation equations. Due to the second-order moment of the subgrade reaction, the quadratic nonlinearity is included in the present model. Moreover, this moment destroys the conservative character of the system. The nonlinear response and the associated stability are examined by means of frequency (force)-response curves, and the shooting method is applied to investigate the dynamic solutions. Particular attention is placed on the effects of the cut-off frequency and boundary conditions. The results show that the cut-off frequency and boundary conditions do not significantly affect the contribution of nonresonant modes to the nonlinear coefficients. Moreover, the effects of foundation models on the three-to-one resonant dynamics of the beam are discussed.

Large amplitude vibration and parametric instability of inextensional beams on the elastic foundation

The nonlinear vibration and parametric instability of the inextensional beam on the elastic foundation are investigated. Considering the inextensional condition and second-order moment of the subgrade reaction, the motion equation of the beam on the elastic foundation is obtained via the Hamilton principle. Then the Galerkin method is applied to obtain the discretized model. The periodic motion is examined by means of the continuation method. Whereas, the numerical simulation is performed to study the nonperiodic motion, particular attention is placed on the nonlinear response of two resonant beams and the parametric instability. Finally, the effects of the boundary conditions and foundation models on the nonlinear vibration of the beams are discussed.

Laser Induced Potential Energy Surface Crossing in Ion-Molecule Reactions: Application to Li++CH4

Abstract Laser ion-molecule reaction interaction through long range dipole moments leads to potential energy surface crossings. We will show here by using gauge representation (electric field gauge) for wave length λ = 20.6 μm, Intensity I = 5×1012 W/cm2, I = 1×1013 W/cm2, I = 3×1013 W/cm2, that we can create laser induced potential energy surface crossing in the virtual transition state region (4.a.u.) where the dipole moment changes sign. We illustrate such effects for the Li H + CH3 + ↔ Li+ + CH4 reaction which takes the form of inverted Morse (without a barrier) using ab-initio methods for calculating the reaction path and the permanent dipole moment of this ion-molecule reaction.

Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites

Based on a consistent set of empirical interatomic potentials, static structure energy calculations of various Al/Si configurations in the supercell of Mg-cordierite and Monte Carlo simulations the phase transition between the orthorhombic and hexagonal modifications of cordierite (Crd) is predicted at 1623 K. The temperature dependences of the enthalpy, entropy, and free energy of the Al/Si disorder were calculated using the method of thermodynamic integration. The simulations suggest that the commonly observed crystallization of cordierite in the disordered hexagonal form could be related to a tendency of Al to occupy T1 site, which is driven by local charge balance. The increase in the Al fraction in the T1 site over the ratio of 2/3(T1): 1/3(T2), that characterizes the ordered state, precludes formation of the domains of the orthorhombic phase. This intrinsic tendency to the crystallization of the metastable hexagonal phase could have significantly postponed the formation of the association of orthorhombic cordierite and orthopyroxene over the association of quartz and garnet in metapelites subjected to granulite facies metamorphism. The textures of local metasomatic replacement (the formation of Crd + Opx Or Spr + Crd symplectites between the grains of garnet and quartz) indicate the thermodynamic instability of the association of Qtz + Grt at the moment of the metasomatic reaction. This instability could have been caused by the difficulty of equilibrium nucleation of orthorhombic cordierite.

Acrosome Reaction of Mouse Epididymal Sperm on Oocyte Zona Pellucida

To improve assessment of the acrosome reaction of mouse epididymal sperm, we employed anti-Izumo1 antibody instead of antibodies against acrosomal proteins. The acrosomal states among acrosome-intact, spontaneously acrosome-reacted, truly acrosome-reacted, and probably dead and/or membrane-damaged sperm were clearly distinguished by combined application of anti-Izumo1 antibody, DNA dye Hoechst 33342, and monoclonal antibody MN7 to paraformaldehyde-fixed sperm. When the acrosome reaction of capacitated epididymal sperm on the oocyte zona pellucida was examined using anti-Izumo1 antibody, approximately 20% of sperm bound onto the zona pellucida were acrosome-reacted 30 min after insemination. We also observed the moment of the acrosome reaction of live sperm on the zona pellucida by time-lapse monitoring using fluorescein isothiocyanate-conjugated anti-Izumo1 antibody.

The First Holocomplex Structure of Ribonucleotide Reductase Gives New Insight into its Mechanism of Action

Ribonucleotide reductase is an indispensable enzyme for all cells, since it catalyses the biosynthesis of the precursors necessary for both building and repairing DNA. The ribonucleotide reductase class I enzymes, present in all mammals as well as in many prokaryotes and DNA viruses, are composed mostly of two homodimeric proteins, R1 and R2. The reaction involves long-range radical transfer between the two proteins. Here, we present the first crystal structure of a ribonucleotide reductase R1/R2 holocomplex. The biological relevance of this complex is based on the binding of the R2 C terminus in the hydrophobic cleft of R1, an interaction proven to be crucial for enzyme activity, and by the fact that all conserved amino acid residues in R2 are facing the R1 active sites. We suggest that the asymmetric R1/R2 complex observed in the 4A crystal structure of Salmonella typhimurium ribonucleotide reductase represents an intermediate stage in the reaction cycle, and at the moment of reaction the homodimers transiently form a tight symmetric complex.

Quantitative Investigation of Torsional Loading of the Tibia during Quick Change of Running Direction

No quantitative information has been reported about tibial loading during quick changes of direction (cutting) during locomotion. The purpose of the present study was to reveal quantitatively the characteristics of tibial torsional loading during zigzag running (ZR) using open-step quick cuts in comparison with straightforward running (SR). Seven adult male subjects were asked to perform SR and ZR at their maximum effort. Ground reaction force (GRF) and 3D motion data were synchronized and sampled during the course of each trial. For tibial loading analysis, net axial moments acting at both (distal and proximal) ends of the tibia were calculated using inverse dynamics. These axial moments were determined as tibial torsional moment based on the assumption that these moments matched well with each other during the stance phase of running (quasi equilibrium assumption). In the present results, the principal direction of the torsional moments seen in the ZR (external/internal rotational loading of the proximal/distal tibia) was opposite to the direction seen in the SR. The mean peak moment as well as angular impulse for the ZR was significantly larger than for the SR (28.8±8.5Nm vs 16.0±8.1Nm, P<0.05; 4.48±1.71Nms vs 1.34±0.69Nms, P<0.01). These results suggested that tibiae tend to be continuously loaded in greater torsion in the opposite direction during the stance phase of open-step cutting compared to straightforward running. Peak moments obtained from individual ZR trials could be successfully regressed with 1) the free moment of ground reaction, 2) shank transversal rotation, and 3) shank sideward tilt (R=0.838, P<0.001). The modifications of these factors would be effective for the reduction of tibial torsional loading during open-step cutting maneuvers.

Coupling of conformational folding and disulfide-bond reactions in oxidative folding of proteins.

The oxidative folding of proteins consists of conformational folding and disulfide-bond reactions. These two processes are coupled significantly in folding-coupled regeneration steps, in which a single chemical reaction (the "forward" reaction) converts a conformationally unstable precursor species into a conformationally stable, disulfide-protected successor species. Two limiting-case mechanisms for folding-coupled regeneration steps are described. In the folded-precursor mechanism, the precursor species is preferentially folded at the moment of the forward reaction. The (transient) native structure increases the effective concentrations of the reactive thiol and disulfide groups, thus favoring the forward reaction. By contrast, in the quasi-stochastic mechanism, the forward reaction occurs quasi-stochastically in an unfolded precursor; i.e., reactive groups encounter each other with a probability determined primarily by loop entropy, albeit modified by conformational biases in the unfolded state. The resulting successor species is initially unfolded, and its folding competes with backward chemical reactions to the unfolded precursors. The folded-precursor and quasi-stochastic mechanisms may be distinguished experimentally by the dependence of their kinetics on factors affecting the rates of thiol--disulfide exchange and conformational (un)folding. Experimental data and structural and biochemical arguments suggest that the quasi-stochastic mechanism is more plausible than the folded-precursor mechanism for most proteins.

The Plane Asymmetric Problem of Impact of a Solid Obtuse Wedge on the Surface of a Compressible Fluid

The plane problem of vertical impact of a solid obtuse wedge, with sides having different inclinations to the surface of a compressible fluid, onto this surface, is analyzed. The solution of the mixed boundary-value problem is reduced to solving an infinite set of linear integral Volterra equations of the second kind for the coefficients of the expansion of the hydrodynamic pressure into a Fourier series by employing methods of integral Laplace transformations in time, separation of variables an expansion into cosine and sine Fourier series. A numerical example of the time dependence of the fluid force, moment of reaction, angle of symmetry and Mach numbers of the sides of submerging wedges of different mass at different deadrise angles is presented.

Collectivisation, révoltes paysannes et politiques gouvernementales [à travers les rapports du GPU d'Ukraine de février-mars 1930

Andrea Graziosi, Collectivization, peasant revolts and government policies through the reports of the Ukrainian GPU (February-March 1930). Seventeen up to now unpublished reports from the former party archives are presented to the reader. They were addressed to the Soviet leadership by the Ukrainian GPU in the cmcial moment of the peasants' reaction to the first wave of collectivization and dekulakization (February-March, 1930). The introductive essay discusses first the genera] interpretative problems they raise, focusing especially on the relationships between 1918-1921 and 1929- 1933, seen as two acts of the same peasant war. It then analyses the specific contributions these reports give to our knowledge of those cmcial months. The essay is concluded by a brief assessment of Western scholarship on collectivization before the opening of Russian archives.