Crystallization as a mass transfer phenomenon

A simple model is assumed for the growth of crystals from solution. It is based on an assumption that the crystal growth depends mainly on two consecutive steps, i.e. diffusion and surface reaction. A calculation procedure is presented for the determination of rate constants for these steps. A newly proposed method was compared with a previous one for the case of the growth of CuSO₄·5H₂O crystals in a fluidized bed crystallizer. The obtained mass transfer coefficients were correlated by means of the Froessling equation.     

On the possibility of increasing the safety of nuclear weapons

All-Russian Research Institute of Experimental Physics, Arzamas-16, 607200. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 2, pp. 169–171, March–April, 1995.     

Historical perspectives on gas hydrates and citation impact analysis

Gas hydrates, or clathrate hydrates, is a multidisciplinary field of research involving potential applications to the oil and gas industry, energy security, and innovative technological applications with literature referenced back to 1810. The field of gas hydrates or clathrate hydrates has progressed over the past several decades from academic curiosity-driven research to industrially relevant research related to flow assurance and methane hydrates in nature as an energy resource. In the recent few decades, several innovative and sustainable applications have emerged with gas hydrate or clathrate hydrate as a technology enabler. In this work, I present a bibliometric analysis of the field of gas hydrates or clathrate hydrates for the period from 1901 to 2020 from the Web of Science core collection database of Clarivate Analytics. In total, 12 152 journal publications (review and original research articles) were analyzed from Web of Science core collection database spanning 121 years (1901–2020). Top countries, top cited review articles, and original research articles along with top source titles (journals) are identified and highlighted. In addition, the field classifications and citation rate trends have been analyzed and presented. Network visualization maps are presented for countries, sources, and organizations by analysing citations in VOSviewer. Co-occurrence analysis is performed to identify the top keywords and their links through network visualization based on VOSviewer.     

Bibliometrics in glass and other sciences: A Plea for reason

We show a scientometric analysis for glass researchers and compare it with those for researchers in two fashionable research topics, representing the science-push area “graphene” and the market-pull area “lithium ion battery (LIB)”. We also present similar statistics for two widely different macro fields, “materials science” (which contains the other three) and “mathematics”. While productivity (number of published articles) of a researcher and his/her H-index are found to be correlated, these correlations are very different for different research fields, depending on their size, fragmentation, interdisciplinarity, and on the community's publication and citation culture. We also explore the correlation between citation statistics and scientific quality and find it to be elusive. While certain bibliometric indexes indeed indicate how active, prolific, and visible a researcher (or a research group) is, we argue that quality—evaluated by the originality, strength, reproducibility and relevance of the findings of a researcher's publications (as judged by peer review)—is much more important than the number of published articles and citations, and this is where efforts must be concentrated by researchers and evaluating bodies.     

Structural control of rubber modified thermoplastic as produced by the mass process

Commercially important polyblends can be produced by a mass process which proceeds via the dispersion of a rubber solution phase. During the process several distinct stages can be identified and structural variation of the final polymer is achieved by controlled agitation. The relationship between the nature and structure of the dispersed phase and the mechanical properties of the polyblend are illustrated and discussed in the light of current theories of impact enhancement.     

Surface mass transfer processes using peat as an adsorbent for dyestuffs

The factors affecting the initial rate of Telon Blue (Acid) dye adsorption onto peat have been investigated. The surface mass transfer coefficients for the rate of dye removal from solution have been determined and correlated as the dimensionless mass transfer term Sh/Sc^0.33. The function Sh/Sc^0.33 has been correlated with respect to four variables, namely, agitation, initial dye concentration, peat particle size range and the temperature of the dye solution. The mass transfer term varies with T^5.5, d_p^0.13, c_o^?1.1 and R.P.M.^0.26; consequently temperature has the most pronounced effect on the mass transfer coefficient.     

Microbial degradation of the detoxification products of mustard from the Russian chemical weapons stockpile

This work was undertaken to examine the possibility of biodegradation of the organic components of the ‘reaction masses’ (detoxification products) generated by destruction of the chemical warfare agent mustard. The composition of these components was analysed by gas chromatography and mass spectrometry. The major components formed during chemical detoxification were identified as 1,4‐perhydrothiazine derivatives. N‐(2‐Hydroxyethyl)‐2‐methyl‐1,4‐perhydrothiazine hydrochloride and N‐(2‐hydroxyethyl)‐3‐methyl‐1,4‐perhydrothiazine hydrochloride were predominant (about 70% of total 1,4‐perhydrothiazine derivatives). Pseudomonas putida strains that used some organic components of the mustard reaction masses as carbon sources for growth were isolated and selected. Growth cessation in this medium (with organic carbon still available) was due to the depletion of bioutilisable substrates, primarily monoethanolamine and ethylene glycol (the residual components of the detoxifying mixture). 1,4‐Perhydrothiazine derivatives were not used as carbon sources for growth of P putida strain SH1, but their concentration decreased during bacterial growth with monoethanolamine and ethylene glycol as the carbon substrates. It is suggested that 1,4‐perhydrothiazines undergo transformation by the microbial cells under these conditions. Copyright © 2005 Society of Chemical Industry     

Longitudinal diffusion and resistance to mass transfer as causes of nonideality in chromatography

The mechanisms of band broadening in linear, nonideal chromatography are examined. A development is presented of a rate theory for this process, wherein nonideality is caused by axial molecular diffusion; axial eddy diffusion; finiteness of transfer coefficient. The correspondence with the plate theory is given, so that the results can also be expressed in heights equivalent to a theoretical plate.The plate theory has been extended to the case of a finite volume of feed; the requirement for this feed volume to be negligible has been examined and a method is presented for evaluating concentration profiles obtained with a larger volume of feed.An analysis is given of experimental results, whereby the relative contributions to band broadening for various cooperating mechanisms could be ascertained.     

Evaporative analyser as a mass detector in the size-exclusion chromatography of coal extracts

The applicability of the evaporative analyser in the size-exclusion chromatography (SEC) of coal derivatives has been explored. The detector, in which the intensity is measured for the light scattered from the finely divided solute particles resulting from evaporation of droplets of chromatographic eluate, is mass responsive, sensitive, and linear for both narrow and gross coal-extract fractions. For molecular masses above 300 the mass response is almost uniform, and there are considerable advantages over the detectors commonly used in SEC. Application to lower molecular mass coal materials is limited by the evaporation of solute along with solvent in the detector.     

Mass transfer studies on multiple emulsion as a controlled mass release system

A novel type of multiple emulsions which contain a microemulsion in macrodroplets, was prepared by a two-step emulsification procedure. Mineral oil was used as the oil phase with a mixture of Aerosol OT and Span 20 as primary emulsifiers. A water-in-oil microemulsion was prepared by gradual addition of water in oil containing both these emulsifiers. This microemulsion system, when dispersed in an aqueous solution containing secondary emulsifier, produces water-in-oil-in-water (W/O/W) multiple emulsions. The release rate of solute dissolved in the internal aqueous phase was measured using the dialysis technique. A theoretical model describing the diffusion of a multiple emulsion system was developed, which predicts the half-life for 50% of the internal solute to diffuse to the external phase. Experimental results showed the stability of multiple emulsions improved significantly upon using a thermodynamically stable microemulsion as a primary emulsion and a polymeric surfactant as a secondary emulsifier. As a resull, half-life of these multiple emulsions is greater than that of conventional multiple emulsions.     

On the use of choking as a boundary for fast fluidizationsimulation of counter-diffusional mass transfer

Fast fluidization is widely regarded as a flow regime between the dilute and dense-phase transport regimes in upward flow of gas-particle suspensions where choking does not occur and the system is insensitive to changes in superficial gas velocity and solids flux. Among the attempts in recent years to predict the boundaries of the fast fluidization regime, the use of the concept of choking appears to be most popular. This paper examines the validity of the use of choking as a boundary for fast fluidization. It is shown that this approach arises from the confusion in the definition of choking. Alternative methods are discussed which would enablebetter prediction of the boundaries of fast fluidization.     

Carbon fibre cloth as an electrode material: electrical conductivity and mass transfer

The paper deals with carbon fibre cloth electrodes, employed in the fabrication of composite materials. The electrical conductivity of single bundles, groups of bundles and cloth is studied. Ohm's law applies to the electrical conduction in the direction of the fibre length, but bundle conductivity decreases with the number of fibres in the bundle. Electrochemical mass transfer between a flowing electrolyte and a cloth arranged as a flow-through or a flow-by porous electrode indicates the existence of double porosity in the material. Due to double porosity, only the external surface of the cloth works as an electrode. This finding shows that the material is not suitable for such an application.     

Polymerized ionic liquids-based hydrogels with intrinsic antibacterial activity: Modern weapons against antibiotic-resistant infections

In this study, the inherent antibacterial activity of 11 different polymerized ionic liquids (PILs)-based hydrogels as well as their corresponding monomers was examined in an extensive screening. The methicillin-resistant Staphylococcus aureus Xen 30 (MRSA Xen 30) and Pseudomonas aeruginosa Xen 5 (P. aeruginosa Xen 5) were chosen as test microorganisms. Both are typical representatives of gram-positive and gram-negative bacteria, respectively. Six of the 11 tested monomers were able to eradicate more than 80% of P. aeruginosa Xen 5 cells in suspension. Unfortunately, the anionic, neutral and zwitterionic representatives lost their function after polymerization. However, the cationic gels retained their antibacterial activity with nearly 100% eradication of selected microorganisms - even at the smallest amount tested. Bactericidal activity against gram-positive MRSA Xen 30 was high when the bacteria were treated with the imidazolium-based monomers. Five of the tested compounds showed rather limited bactericidal activity <50% killed bacteria. The weak antibacterial activities could be significantly increased by crosslinking them to three-dimensional networks. As a result, all the hydrogels possessed strong killing efficiencies of at least 68% and were able to maintain this activity even at low hydrogel volume fractions. These findings are very promising for the development of new antibacterial materials for medical applications, for example, stent coatings.     

Development and experimental evaluation of aerodynamic lens as an aerosol inlet of single particle mass spectrometry

This study described a development and an experimental evaluation of an efficient aerodynamic lens inlet of the single particle mass spectrometry. Several key designing parameters and systematic factors were investigated for the whole lens system through a full numerical simulation. From many tests for various designs of the system, we showed that Mach number was not an independent parameter but interrelated well with flow Reynolds numbers and pressures upstream of the orifices. By manipulating the parameters, we showed for the first time a possibility that there exist a universal correlation between optimal Stokes number and a new factor incorporating the other dimensionless variables and a design parameter. The universality was confirmed by the full simulation results. We demonstrated that the new design of the system was capable of focusing ultrafine aerosols in the size range of 30–700 nm. At two different operating conditions, the formations of sub-millimeter beams of 30–300 nm NaCl aerosols are verified by light scattering imaging as well as microprobe observation of deposited aerosol beams. Finally, the measured sizes of aerosol beams agree reasonably well with those from the simulations as a function of particle size.