The Transformation of Inorganic and Methylmercury in the Presence of l-Cysteine Capped CdSe Nanoparticles

Transformations of mercury (Hg) forms in the aquatic environment is a crucial aspect of Hg fate, transport and the bioaccumulation of methylmercury (CH3Hg; MeHg), which is the form that drives most human health concerns. Transformations between Hg forms on surfaces have been inadequately studied but here we report on the interaction of inorganic Hg (HgII) and MeHg with chalcogenide nanoparticles (NPs); specifically L-cysteine capped CdSe nanocrystals. The study sheds light on the transformation of the Hg species and the interaction mechanisms, by examining the product composition, reaction mass balance and the distribution between the liquid and solid phase. The results showed that the quenching of the photoluminescence (PL) of CdSe NPs was greater for HgII than MeHg, and that HgII caused significant PL quenching even when its concentration was in the nM range. Over 90% of HgII was found associated with the solid phase while most MeHg existed in the liquid phase in the experimental solutions. No dimethylmercury ((CH3)2Hg; DMeHg) was produced from the interaction of MeHg and the NPs, in contrast to findings with microparticles. However, a fast and complete MeHg transformation into HgII occurred when the MeHg + NPs mixture was exposed to light. A scheme for the MeHg degradation was derived and is presented, and it was concluded that the precipitation of HgSe accelerated the MeHg degradation. These results provide insight into the abiotic pathways for MeHg degradation in environmental waters in the presence of NPs.

Proton-transfer-reaction mass spectrometry (PTR-MS) for online monitoring of glucose depletion and cell concentrations in HEK 293 gene therapy processes

Objectives The applicability of proton-transfer-reaction mass spectrometry (PTR-MS) as a versatile online monitoring tool to increase consistency and robustness for recombinant adeno-associated virus (rAAV) producing HEK 293 bioprocesses was evaluated. We present a structured workflow to extract process relevant information from PTR-MS data. Results Reproducibility of volatile organic compound (VOC) measurements was demonstrated with spiking experiments and the process data sets used for applicability evaluation consisted of HEK 293 cell culture triplicates with and without transfection. The developed data workflow enabled the identification of six VOCs, of which two were used to develop a soft sensor providing better real-time estimates than the conventional capacitance sensor. Acetaldehyde, another VOC, provides online process information about glucose depletion that can directly be used for process control purposes. Conclusions The potential of PTR-MS for HEK 293 cell culture monitoring has been shown. VOC data derived information can be used to develop soft sensors and to directly set up new process control strategies.

Building a mathematical model of technological processes in the acetic acid synthesis reactor

The result of the study reported in this paper is the proposed mathematical model of technological processes occurring in the reactor for acetic acid synthesis. The initial parameters of the reactor considered were the value of the concentration of acetic acid at the reactor outlet, temperature, the level of reaction mass, and pressure in the reactor. The input parameters included the amount of methanol and carbon monoxide supplied. Material and thermal balances of reactor technological processes were used to construct the mathematical model of the reactor. Fisher criterion was applied to test the mathematical model for adequacy. At the specified 5 % level of significance, the value of Fisher criterion for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for a stationary mode. The reproducibility of the modeling results was tested using the Cochran criterion. The value of the Cochrane criterion, at the predefined 5 % level of significance, for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for different modes. The relative error for the modeled output parameters was calculated. The relative error of the initial parameters did not exceed the level of 10 %. The model built makes it possible to calculate with satisfactory accuracy the value of the concentration of acetic acid at the reactor output, the temperature and level of the reaction mass in the reactor under a stationary mode. The resulting model could be used to automate the control of technological processes in the acetic acid synthesis reactor under a stationary mode. The study results open additional opportunities to manage the stationary mode of the reactor

Reconstruction of the hardware design for isopropylbenzene production for the production of ethylbenzene

The hardware design of the rectification unit for the production of isopropylbenzene in the presence of the AlCl3 catalyst is considered, the use of which has a number of problems associated with its corrosiveness, rapid deactivation, the complexity of regeneration, etc. One of the possible solutions to the listed technological disadvantages is the use of heterogeneous zeolite-containing catalysts. In this case, during the reconstruction of the existing production of isopropylbenzene in the technological scheme of separation of alkylate, three rectification columns are released, which are expediently used to separate the alkylate of ethylbenzene production. To study the possibility of using the discharging distillation columns, a computational experiment was carried out using the Honeywell UniSim Design modeling system, in which a model of the alkylate separation unit for ethylbenzene production was formed. The NRTL method was used as a mathematical package for calculating the thermodynamic properties of the mixture components. As a result of modeling the operation of the alkylate separation unit for each distillation column, the optimal operating process parameters were obtained: pressure of the top and bottom of the column, reflux ratio, temperature profile along the height of the column. The calculated material balance of the technological scheme shows that in the first distillation column, complete separation of benzene from the alkylation reaction mass is achieved, the second column ensures the production of commercial ethylbenzene, and in the third column, a fairly clear separation of diethylbenzene from the remaining components of the mixture is obtained. The performed computational experiment showed that for the organization of the stable operation of the technological scheme for the separation of alkylate in the production of ethylbenzene, it is possible to use all the considered distillation columns without changing their design parameters at a load on the reaction mass of alkylation of about 60 t / h.

Усиление внутреннего слоя многослойного композита базальтопластиком в виде сотовой структуры

In our studies we present a multilayer structure consisting of outer layers of two-ply basalt composed of basalt fabric impregnated with an epoxy compound and an inner layer of polyurethane reinforced with basalt, having the same composition, formed in conjugate hexagonal prisms, and forming a cellular framework. The main part describes the technological sequence of obtaining basalt face layers, basalt hexagonal cellular frame, and filling it with a liquid reaction mass of rigid polyurethane system. The formation of a single multilayer composite structure is shown. We also present the results of the experimental research of strength of a laminated composite and its inner layer without facing layers when tested for static bending with concentrated load increasing at a constant rate and compression testing up to 10% of relative deformation. It describes the effect of the size of hexagonal prismatic cells of the frame on the physical and mechanical characteristics of the middle layer. The reduction of the cell size results in the increase of the composite strength. The dependence of the composite density on the size of the cells of the basalt frame has been studied.

PALLADIUM-CATALYZED ALKOXYCARBONYLATION OF ARYL BROMIDES AT ATMOSPHERIC PRESSURE

Исследование развивает направление каталитического алкоксикарбонилирования арилбромидов в жидкой фазе при атмосферном давлении. В качестве каталитической системы предложена система на основе бисацетонитрилхлорида палладия, стабилизированного в промышленной полистирольной сетке MN100. В ходе исследования было изучено влияние природы фосфинового лиганда, температуры реакционной массы, а также соотношения субстрат: катализатор на скорость и интегральную селективность процесса жидкофазного алкоксикарбонилирования пара-броманизола газообразным оксидом углерода (II). Исследована активность процесса в присутствии трифенилфосфина, трифенилфосфиноксида и 4,5-бис(дифенилфосфино)-9,9-диметилксантана. The study develops the direction of catalytic alkoxycarbonylation of aryl bromides in the liquid phase at atmospheric pressure. A catalyst based on palladium bisacetonitrile chloride stabilized in an industrial MN100 polystyrene mesh is proposed as a catalytic system. In the course of the study, the influence of the nature of the phosphine ligand, the temperature of the reaction mass was studied. The effect of the substrate-to-catalyst ratio on the rate and integral selectivity of the liquid-phase alkoxycarbonylation of para-bromanisole with carbon (II) oxide gas was also studied. The activity of the process was studied in the presence of triphenylphosphine, triphenylphosphinoxide, and in the presence of 4,5-bis (diphenylphosphino)-9,9-dimethylxanthane.

DEVELOPMENT OF THE METHOD AND OPTIMIZATION OF THE COMPOSITION AND MODES OF OBTAINING THE BIODEGRADABLE GREASE WITH THE LITHIUM-CALCIUM THICKENER

It is noted that the development of biodegradable lubricants is an integral part of the development of a modern “green” economy. The distinctive features of the proposed method are described for producing a biodegradable grease on a mixed lithium-calcium thickener, providing for the introduction of alkaline initial components of the dispersed phase (lithium hydroxide monohydrate and calcium hydroxide) into the reaction mass not in the form of their aqueous solutions, but in a powdery state, and the exception of prolonged exposure to water and high temperature on a component of a dispersion medium of plant origin (rapeseed oil) in the process of lubricant synthesis. Along with this, it was proposed to use a highly refined oil of group III according to the API (American Petroleum Institute) standard as a mineral component of the dispersion medium. This provides, in aggregate, the higher stability of the rheological and tribological characteristics of the grease (for at least 12 months) at a given level of biodegradability. The experimental-statistical mathematical model of the process of obtaining the biodegradable lithium-calcium grease is developed, which makes it possible to determine the parameters of the component composition (the content of the mixed lithium-calcium thickener in the grease and the content of lithium stearate in the mixed thickener) and the synthesis modes (the heat treatment temperature of the reaction mass) to achieve the given level of the main characteristics of the finished grease (penetration, dropping point) while ensuring its biodegradability of at least 80 %.