Reversible ATP-dependent inactivation of adipose diacylglycerol acyltransferase

Diacylglycerol acyltransferase from rat adipose tissue is shown to be inactivated by 30 to 40% upon incubation with adenosine 5′-triphosphate (ATP) and Mg²⁺. The activity responsible for this inactivation is associated with the cytosolic fraction, specific for ATP, prevented when ATP is substituted by β,γ-methylene-ATP, and partially blocked by 1 mM ethylenediaminetetraacetate or 40 mM NaF, but not by inhibitors of adenosine 3′,5′-cyclic-monophosphate (cAMP)-dependent protein kinase and/or protein kinase C (PKC). The cytosolic activity cannot be mimicked by (cAMP)-protein kinase nor by PKC. Inactivated diacylglycerol acyltransferase from ATP/cytosol-treated microsomes can be reactivated by incubation with partially purified protein phosphate from rat liver, and can be inactivated again by further addition of ATP in the presence of cytosol. The results suggest the existence in adipose tissue of a protein kinase other than cAMP-protein kinase or PKC, which may be involved in the regulation of triacylglycerol synthesis.     

Reversible carbonylation/decarbonylation of zeolite-entrapped tetrairidium clusters

Iridium carbonyl clusters in NaY zeolite have been prepared from adsorbed [Ir(CO)₂(acad)]. The infrared spectra and the yellow color of the sample are consistent with the formation of Ir₄(CO)₁₂] in the zeolite cages, presumably the product of reductive carbonylation of the mononuclear precursor. The iridium carbonyl cluster in the zeolite could be decarbonylated by treatment with flowing H₂ at 300 ° C and 1 atm and recarbonylated by treatment with CO at 40 °C and 1 atm. The carbonylation/decarbonylation process is reversible, provided that the temperature of the decarbonylation is low, which suggests that the decarbonylated clusters may be Ir₄. Treatment of the sample in H₂ at 425 ° C and 1 atm led to the formation of particles or iridium metal outside the zeolite pores.     

Reversible inactivation of the CG specific SssI DNA (cytosine-C5)-methyltransferase with a photocleavable protecting group

Caging of proteins by conjugation with a photocleavable group is a powerful approach for reversibly blocking enzymatic activity. Here we describe the covalent modification of the bacterial SssI DNA methyltransferase (M.SssI) with the cysteine-specific reagent 4,5-dimethoxy-2-nitrobenzylbromide (DMNBB). M.SssI contains two cysteine residues; replacement of the active-site Cys141 with Ser resulted in an approximately 100-fold loss of enzymatic activity; this indicates an important role for this residue in catalysis. However, replacement of Cys368 with Ala did not affect methyltransferase activity. Treatment of the Cys368Ala mutant enzyme with DMNBB led to an almost complete loss of activity. Irradiation of the inactivated enzyme with near-ultraviolet light (320-400 nm) restored 60 % of the catalytic activity. This indicates that caging by DMNBB can be used for the reversible inactivation of M.SssI.     

Reversible Weight Change of Acceptor-Doped BaTiO3

The oxygen vacancy concentration of BaTiO₃ doped with acceptors (Cr to Ni) is determined gravimetrically as a function of the O₂ partial pressure during and after annealing at 700° to 1300°C. The oxygen vacancy concentration of these materials is larger than that of undoped and donor-doped BaTiO₃. The oxygen vacancies are doubly ionized and they compensate the acceptors of lower valence. Both the vacancy concentration and the valence of the acceptor dopants depend on the annealing conditions. The electronic energy levels of the acceptors within the BaTiO₃ band gap are derived from the gravimetric measurements. The electrical properties of the acceptor-doped ceramics are favorable for base-metal-electrode multilayer capacitors, which require sintering in reducing atmospheres.     

羧甲基壳聚糖病毒灭活/去除工艺验证

目的对羧甲基壳聚糖病毒灭活/去除工艺进行验证。方法模拟生产条件,选择猪细小病毒(porcine parvovirus,PPV)、伪狂犬病病毒(pseudo rabies virus,PRV)、鸭肝炎病毒Ⅰ型(duck hepatitis virus-Ⅰ,DHV-Ⅰ)、牛滤过性腹泻病毒(bovine viral diarrhea virus,BVDV)作为指示病毒,采用高温碱化和醇洗灭活/去除病毒,Karber法计算病毒滴度,荧光PCR检测病毒灭活/去除效果。结果 3批甲壳素经碱化反应处理,PRV、PPV、BVDV、DHV-Ⅰ的平均灭活对数值分别为≥6.736、≥6.597、≥6.138和≥5.806 log TCID50/0.1 ml;3批羧甲基壳聚糖经醇洗处理,PRV、PPV、BVDV、DHV-Ⅰ的平均灭活对数值分别为≥6.763、≥6.569、≥6.167和≥5.587 log TCID50/0.1 ml。碱化反应与醇洗处理前感染PRV、PPV、BVDV、DHV-Ⅰ样品荧光PCR检测平均Ct值分别为23.465、23.387,24.873、24.706,26.887、25.376,27.386、24.629,处理后样品的荧光PCR检测平均Ct值均40。结论羧甲基壳聚糖经高温碱化和醇洗反应处理均能有效灭活病毒,保证了产品的安全性。     

Pd/C催化剂失活原因探讨

从PTA加氢精制反应原理探讨了Pd C催化剂失活原因及解决方法。生产过程中的工艺参数控制 ,操作和原料质量是影响Pd C催化剂活性的主要因素 ,稳定反应器操作 ,更换腐蚀严重的管线及设备 ,提高保护床层高度 ,用强碱液冲洗反应器床层等可再生和延长Pd C的寿命     

Reversible Stress-Induced Martensitic Transformation in ZrO2

Optical observations and X-ray measurements were used to detect the martensitic transformation of tetragonal ZrO₂ to the monocline structure during room-temperature stressing of Mg-PSZ. The transformation occurs at stresses as low as ∼200 MPa and is reversible. Additional observations of transformation around Vickers indentations and cracks suggest that application of much higher stresses prevents the reverse transformation on unloading.     

High pressure CO2 inactivation of food: A multi-batch reactor system for inactivation kinetic determination

A multi-batch apparatus was developed for investigating food inactivation by high-pressure CO₂, both for performing preliminary studies on CO₂–substrate interactions and for measuring the inactivation kinetics of the microorganisms suspended in food matrices. Experiments were carried out for inoculated liquid growth medium and fruit juices, using the yeasts Saccharomyces cerevisiae ATCC 9763 and Pichia awry wild type as test microorganisms. Different combinations of temperature (38 and 32 °C), pressure (90 and 75 bar) and treatment time were investigated. The logarithmic inactivation kinetic curves showed a quite linear behavior with a slope change in some cases. It was also shown that the pasteurization degree of the considered foodstuffs depends on the physical–chemical properties of the treated substrate.The proposed multi-reactors system allows to save both working time and materials, giving a better collection of experimental data in terms of reliability and homogeneity.     

Reversible Transformation and Elastic Anisotropy in Mg-ZrO2

Mechanical loading of polycrystalline ZrO₂ ceramics causes reversible, out-of-plane distortions at free surfaces that are parallel to the direction of applied stress. These distortions have been measured using optical interference microscopy, and the separate contributions due to elastic anisotropy and reversible mantensitic tranformation have been identified.     

Microbial inactivation of paprika using high-pressure CO2

Herein, we describe the use of high-pressure CO₂ for the inactivation of the natural bio-burden of paprika and an evaluation of its effects on product quality. The treatments were carried out with a continuous flow of CO₂ through a bed of paprika, varying the initial moisture (<35%), pressure (60-300 bar), temperature (<95 °C) and exposure time (10-150 min). Comparison was made with thermal treatment at the same temperature and moisture levels to isolate the effects of the CO₂. It was difficult to achieve a total elimination of the highly resistant spores due to the low water activity of the medium. The paprika did not appear to exert a protective effect. Neither the use of techniques to improve the CO₂-paprika contact nor pressure cycling had any effect. The most influential parameters were the initial water content and temperature, presumably due to their contributions to the activation/germination of spores, making these microbes vulnerable to CO₂ attack. However, we found that their values should be kept under 25-30% and 85-90 °C, respectively, to avoid a loss of product quality. Pressure could be maintained at relatively low levels (60-100 bar) because it did not significantly contribute to any of the possible CO₂ sporicidal mechanisms and at higher values caused oleoresin extraction. Under these conditions, treatment times on the order of 30-45 min were sufficient to achieve the disinfection and total count reduction required by the most exigent clients. The treated paprika retained its colour category and its final humidity was within the legal levels for secure storage. Therefore, the method could be a useful alternative to traditional moist-heat treatments or hydrostatic processes.     

Electrical-Triggered Multicolor Reversible Color-Changing Ag Nanoparticles/Reduced Graphene Oxide/Polyurethane Conductive Fibers

Smart color-changing fibers attract much attention owing to their importance as a component of flexible electronics. A facile and scalable method of multicolor reversible electro–thermochromic Ag nanoparticles/reduced graphene oxide/polyurethane conductive fiber (ETC AgNPs/rGO/PU conductive fiber) is fabricated, which contains the polyurethane (PU) as the inner layer, reduced graphene oxide (rGO) with Ag nanoparticles (AgNPs) as the conductive layer, and thermochromic paste as the outermost layer. It possesses excellent electrothermal and color-changing properties and rapidly generates Joule heat at 0.5 V, which makes the fiber surface temperature reach 39.81 °C rapidly. The color switching rate is fast and changes from green to yellow within 2 s. During the process of 250 times on/off voltage, ETC AgNPs/rGO/PU conductive fibers still maintain excellent electrical and thermal properties and color change stability; even in the washing, strong acid, and strong alkali environment, they still have excellent durability. This human subjective adjustable electrical–thermal–color multi-level induced modulation makes it possible to be applied to smart wearable fields such as visual camouflage, personal thermal management, and active information transfer.     

Use of thermolysin metalloprotein affinity metal chromatography in the decontamination of actinide-bearing solutions

Thermolysin metalloprotein affinity metal chromatography (MAMC) has been shown to be effective for the removal and concentration of lanthanide and actinide ions from aqueous solution. Using solution of trivalent lanthanide ions of appropriate radii and of Th⁴⁺ and UO ions as models, the calciumbinding sites of immobilized thermolysin have shown appreciable potential for the decontamination of actinide-bearing waster solutions. The zinc-binding site of the affixed protein may also be used for the removal and concentration of divalent transition metal ions.     

Reversible electrochemical insertion of anions in poly-p-phenylene from aqueous electrolytes

Poly-p-phenylene (PPP) was synthesized from benzene according to the Kovacic method. Electrodes were made from this electronic insulator by cold- or hot-pressing of the loose, brown powder, under the addition of 7.5 wt. % soot (Corax L^®, Degussa AG). The electrochemical insertion and removal of anions HSO⁻₄, ClO⁻₄ in this material in aqueous solutions of the corresponding acids was investigated by slow cyclic voltammetry.

Initially, only a surface layer of about 0.1 mm thickness takes part in the electrochemical processes, which are reversible. A maximum concentration of anions in the solid of [(−C₆H₄−)⁺₇ A⁻] is attainable. The maximum degree of insertion is equal to 0.14. The insertion potential U_I shifts strongly into the negative direction with increasing concentration c of the acid. A linear U_I/c relationship is observed as in the case of graphite, where the intercalation potential is more positive by 20–200 mV for the same electrolyte. The round trip current efficiency for the insertion/removal cycle increases with increasing acid concentration attaining 100% in 14 M H₂SO₄ or 11.3 M CHlO₄. For a given concentration, increases in the same order as with graphite (H₂SO₄ < HClO₄ < HBF₄), being somewhat lower for a given electrolyte composition. From anodic current limitation (j_lim = 5–10 mA cm⁻²), a diffusion coefficient of about D = 2 × 10⁻⁷ cm² s⁻¹ is derived for the transport of anions in the bulk of PPP. The striking similarity of our results to former findings with graphite is thoroughly discussed. Some general conclusions are derived thereof.     

Reversible Electrochemical Control over Photoexcited Luminescence of Core/Shell CdSe/ZnS Quantum Dot Film

Semiconductor quantum dots (QDs) are widely used in light-emitting diodes and solar cells. Electrochemical modulation is a good way to understand the electrical and optical properties of QDs. In this work, the effects of electrochemical control on photoluminescence (PL) spectra in core/shell CdSe/ZnS QD films are studied. The results show different spectral responses for surface emission and core emission when a negative electrochemical potential is applied: the core emission is redshifted while the surface emission is blueshifted. The former is attributed to the electrostatic expansion of the excitonic wave function, due to the asymmetric distribution of adsorbed cations on the surface of the dots. The latter is attributed to the occupation of lower surface states by the injected electrons, i.e., the photoexcited electrons are more likely to be trapped onto higher surface states, leading to a blueshift of the surface emission. Both the spectral shift and the accompanying PL-quenching processes are reversible by resetting the potential.     

Reversible photochromic nanofibrous membranes with excellent water/windproof and breathable performance

Electrospun nanofibrous membranes (NFMs) with outstanding photochromic property, waterproof, and breathability have attracted considerable interest owing to their multifunctional applications in intelligent clothing, self‐cleaning, and protection. However, great challenges still remain in creating such functional materials. A novel waterproof–breathable membrane with robust photochromic property is fabricated by introducing photochromic microcapsule (PM) into electrospun thermoplastic polyurethanes (TPU) membranes. Compared with the pristine TPU NFMs, the composite TPU/PM membranes are endowed with reversible photochromic properties. In addition, the composite membranes not only exhibited a water contact angle of 137° and a milk contact angle of 130°, but also had integrated properties of modest water vapor transmittance rate of 19,278 g m^?2 day^?1, high air permeability of 962 mm s^?1, low waterproofness of 2.813 kPa, and comparable tensile strength of 12.08 MPa. Furthermore, the convenience and efficiency of this fabrication process will allow for large‐scale production of the multifunctional NFMs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46342.     

Reversible sorption–desorption of NOx by mixed oxides under various atmospheres

Characteristics of MnO_y–ZrO₂ and Pt–ZrO₂–Al₂O₃ as reversible sorbents of NO_x were investigated under dynamic changes in atmosphere. These sorbents can be used reversibly with a change of C₃H₈ concentration in the reaction gases. Catalytic reduction of NO occurred in the presence of propane, which was more pronounced on Pt–ZrO₂–Al₂O₃ than on MnO_y-ZrO₂ due to high activity of Pt surface for this reaction on MnO_y in MnO_y–ZrO₂. The sorption was observed as soon as the atmosphere changed from a reducing to an oxidizing one. This implies that a high equilibrium partial pressure of O₂ is necessary for NO uptake since the sorbed NO⁻₃ species becomes stable. The beginning of NO_x desorption atmospheres was somewhat dependent on the amount of stored NO_x. The presence of propane in the gas phase strongly affected the characteristic sorption and desorption properties of MnO_y–ZrO₂ and Pt–ZrO₂–Al₂O₃. The sorption and desorption properties are different for MnO_y–ZrO₂ and Pt–ZrO₂–Al₂O₃, since the noble metal or metal oxide possesses unique activity for the NO reaction with C₃H₈ and the amount of oxygen available for oxidative sorption of NO.     

Reversible isomerisation of alkyl aromatics

The isomerisation of different alkyl naphthalenes under the influence of anhydrous sulphonic acids, other Friedel-Crafts and Lewis acid catalysts has been studied, where the alkyl groups undergo rearrangement during the isomerisation process. Isomerisation of benzylnaphthalenes, in presence of phenol and naphthols, resulted in the alkylation of such solvent nuclei, giving benzylphenols and benzylnaphthols together with the normal products of isomerisation.     

Reversible collapse and Mg release of de- and rehydroxylated homoionic cis-vacant montmorillonites

Homoionic Na⁺, Ca²⁺, Sr²⁺, Li⁺, Cu²⁺ and Zn²⁺ samples of the <2 μm fraction of a cis-vacant montmorillonite from Linden (Bavaria) were steam treated at 200°C (≈1.5 MPa), 240°C (≈3.3 MPa) and 300°C (≈8.0 MPa) after dehydroxylation at temperatures up to 630°C. Cation exchange capacity (CEC) measurements, determination of exchangeable cations and X-ray diffraction (XRD), supplemented by thermoanalytical investigations of the evolved water in a thermobalance linked to a mass spectrometer, infrared (IR) and electron spin resonance (ESR) spectroscopy were employed to obtain information about the state of expandability and structural changes of swellable montmorillonite and the sites of interlayer and octahedral cations after heating and rehydroxylation.The XRD pattern of the initial samples showed a well-defined (001) reflection according to the interlayer cation and its hydration state under laboratory atmosphere. After dehydroxylation the pattern exhibited (001) reflections between 9.6 and 9.8 Å, corresponding to a collapsed structure for all samples. The Na⁺-, Ca²⁺- and Sr²⁺-rich montmorillonites regained partial expandability after rehydroxylation at 200°C and full expandability after rehydroxylation at 300°C if the dehydroxylation temperature was less than 630°C. Rehydroxylation at 300°C of the Cu²⁺- and Zn²⁺-rich montmorillonites did not cause reexpansion, whereas the Li⁺-rich samples recovered a partial swellability after rehydroxylation at 240°C and nearly the full swellability after rehydroxylation at 300°C.The Li⁺-, Cu²⁺- and Zn²⁺-rich samples underwent a strong CEC reduction due to migration of the interlayer cations into the 2:1 layer before dehydroxylation started. After rehydroxylation under water steam Cu²⁺- and Zn²⁺-rich samples released 16–30 meq/100 g of Mg²⁺ from the structure, increasing with the steam temperature. Mg²⁺ release was not observed for the Li⁺-rich montmorillonite.     

Reversible thermochromic behavior and mechanism of Congo red/palygorskite nanohybrid induced by mechanochromism

Journal of Porous Materials - To better understand the effect of the interaction of dye molecules at the interface of clays on thermochromism, we report here a new preparation strategy for a...