Adsorption at various interfaces has concerned scientists since the beginning of this century. This phenomenon underlies a number of extremely important processes of utilitarian significance. The ...technological, environmental and biological importance of adsorption can never be in doubt. Its practical applications in industry and environmental protection are of paramount importance. The adsorption of substrates is the first stage in many catalytic processes. The methods for separation of mixtures on a laboratory and on an industrial scale are increasingly based on utilising the change in concentration of components at the interface. Moreover, such vital problems as purification of water, sewages, air and soil are involved here too. On the other hand, many areas in which technological innovation has covered adsorption phenomena have been expanded more through art and craft than through science. A basic understanding of the scientific principles is far behind; in part because the study of interfaces requires extremely careful experimentation if meaningful and reproducible results are to be obtained. In recent years, however, considerable effort has been increasingly directed toward closing the gap between theory and practice. Crucial progress in theoretical description of the adsorption has been achieved, mainly through the development of new theoretical approaches formulated on a molecular level, by means of computer simulation methods and owing to new techniques which examine surface layers or interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and heterofullerenes, microporous glasses and nanoporous — both carbonaceous and inorganic — materials. Nanostructured solids are very popular in science and technology and have gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal properties. Although the development of adsorption up to the 1918s has been following rather a zig–zag path, this arm of surface science is now generally considered to have become a well-defined branch of physical science representing an intrinsically interdisciplinary area between chemistry, physics, biology and engineering. This review presents in brief the history of adsorption and highlights the progress in theoretical description of the phenomenon under consideration. The paper deals with the above problems critically, showing the development of adsorption, presenting some of the latest important results and giving a source of up-to-date literature on it. Moreover, in this paper the most important aspects are overviewed referring to today's trends and visions in application of adsorption science in industry, environmental protection and in environmental analysis.
The relationship between development of
adsorption theory and adsorption practice is pointed out. Current understanding and perspectives pertaining to applications of adsorption phenomena on laboratory and on industrial scale as well as environmental protection are discussed and illustrated by means of a few spectacular examples.
The transition from petroleum to biorenewable sources of carbon to meet our energy and chemical feedstock needs is difficult, in part because these sources are so different, with petroleum being ...under-functionalized and biomass being over-functionalized relative to commercial chemicals. However, target lists such as the US Department of Energy’s Top 10 have converged efforts to develop the technologies needed to manufacture the most important feedstocks accessible from biorenewables. Less well defined but equally important to the economic viability of an integrated biorefinery are low-volume, high-value product streams, which would help offset the capital costs of a biorefinery. In this Review, we attempt to bring together some of the advances that could fill these niche areas, with a focus on the conversion of cellulosics into chemicals using homogeneous catalysis. The products range from high-value jet fuels to monomers for high-performance polymers and materials to pharmaceutical intermediates and cover a broad range of structural complexities.A move away from fossil fuels as an energy source will also require a move to new sources for important chemical feedstocks. This Review considers the use of homogeneous catalysis to convert cellulosics into low-volume, high-value chemicals that are currently derived from crude oil.
In the last decade, vitamin D was in the spotlight in many fields of research. Despite numerous publications, its influence on reproductive health remains ambiguous. This paper presents an up-to-date ...review of current knowledge concerning the role of cholecalciferol in human reproduction. It covers various infertility issues, such as polycystic ovary syndrome, endometriosis, myoma-induced infertility, male infertility, premature ovary failure and in vitro fertilization techniques. Vitamin D deficiency, defined as serum concentration of 25-hydroxycalciferol of less than 50 nmol/L, is commonly noted more frequently than only in fertility clinic patients. It is a global trend that is observed in all age groups. The results of original publications dated up to 2015 have been summarized and discussed in a critical manner. Most experts agree that vitamin D supplementation is a necessity, particularly in women suffering from obesity, insulin resistance or small ovarian reserve, as well as in men with oligo- and asthenozoospermia if serum concentration should fall below 50 nmol/L (normal range up to 125 nmol/L). High concentration of vitamin D and its metabolites in decidua during the 1st trimester suggests its important role in the implantation process and a local immunological embryo-protection. On the other hand, evidence-based research did not prove a significant difference so far in ovulation stimulation or embryo development depending on vitamin D level. In one of the publications, it was also found that vitamin D binding protein (VDBP) has a molecular similarity to anti-sperm antibodies, and another one concluded that both low (<50 nmol/L) and high (>125 nmol/L) concentration of vitamin D are associated with decreased number and quality of spermatozoa in semen. Vitamin D is definitely not a Trojan Horse in reproductive health, since there were no adverse effects reported for vitamin D intake of up to 10,000 IU/day, but to proclaim it the Golden Fleece, more evidence is needed.
The study was conducted to investigate secretory activity and define the paracrine potential of mesenchymal stem cells from human umbilical cord and amniotic membrane (UC-MSCs and AM-MSCs, ...respectively).
UC-MSCs (n = 6) were obtained from tissue explants using an adherent method after two weeks of incubation. AM-MSCs (n = 6) were obtained by digestion with tripsin and collagenase. MSC phenotype was confirmed in vitro by performing flow cytometry, differentiation assays and vimentin staining. Supernatants were collected after 48 h culturing in serum-free conditions and the following concentrations were determined: epidermal growth factor (EGF), interleukin (IL)-6, IL-10, tumor necrosis factor-α, transforming growth factor-β (TGF-β), vascular endothelial growth factor-α (VEGF-α) and metalloproteinase (MMP) 1, 8 and 13, using multiplex supernatant cytokine assay. Data were compared with adipose tissue derived MSCs (AD-MSCs, n = 6).
Both UC-MSC and AM-MSC populations were positively identified as MSCs by flow cytometry and differentiation potential into bone, cartilage and adipose tissue. Using a multiple cytokine detection assay, we proved that both UC-MSCs and AM-MSCs show high secretive capacity. However, the secretion profile differed between cells from various sources. UC-MSCs showed significantly higher production of TGF-β and lower production of VEGF-α, compared to AD-MSCs (P = 0.004) and AM-MSCs (P = 0.039) and lower levels of EGF (P = 0005). AM-MSCs showed significantly lower levels of MMP-8 than UC-MSCs (P = 0.024); however, there was no difference in levels of released cytokines compared to AD-MSCs.
AM-MSCs show similar IL production as AD-MSCs, while UC-MSCs have a significantly different profile, which suggests diverse biological potential of both cell types for immunomodulative and regenerative therapy.
This paper examines whether the effects of oil market shocks on economic activity and exchange rates in oil-exporting countries depend on the stage of economic development or the scale of oil ...exports. Within the framework of block-exogenous Interacted Panel Vector Autoregression (IPVAR), we show that both oil price and oil price uncertainty shocks affect the economies of oil-exporting countries. The responses of domestic variables to oil market shocks are heterogeneous across countries and the scale of these responses depend on the level of economic development. In general, the reaction of emerging market economies is more prominent than that of advanced economies. The combined contribution of oil market shocks to exchange rate volatility is inversely associated with the stage of economic development, but no such relation is observed for industrial production. The results obtained are robust to conditioning the responses on the scale of oil exports, restricting the sample to the non-covid pandemic period, and using the alternative measure for oil price uncertainty.
•Oil-exporting countries are susceptible to both oil price and uncertainty shocks•The interacted panel VAR model is used in order to embed country characteristics•The responses of emerging market economies are more prominent and longer lasting•Oil market shocks contribute to exchange rate volatility•The contribution is inversely associated with the stage of economic development
A B(C6F5)3-catalyzed method for the selective conversion of unsaturated carbohydrates to cyclopentanes and cyclopropanes is disclosed. Catalyst activation of tertiary silanes generates the ion pair ...(C6F5)3B–HROSi2 whose components synergistically activate C–O bonds for diastereoselective C–C bond formation. Sila-THF cations are invoked as key intermediates facilitating carbocyclizations. Complex chiral synthons are thereby obtained in a single pot.
This paper offers a novel approach to the estimation of an active component of reserves making use of a time-varying coefficient model estimated with Bayesian techniques. The approach substantially ...extends the time and country coverage of estimates beyond that available under the existing approach. We find that the estimates of an active component for 20 countries over 1995–2017 period are highly correlated with those obtained from the existing approach. The new estimates are cross-checked against the available data on FX market interventions in Argentina, Chile, the Czech Republic, Mexico, Russia and Turkey. We demonstrate that these estimates are a better proxy of FX interventions than simple changes in reserves and are at least as good as the estimates from the existing approach. Our novel approach contributes to a better understanding of changes in FX reserves in many countries, including large reserve holders for which the relevant data are hardly available.
•A novel approach to the estimation of an active component of reserves is developed.•A time-varying coefficient model is estimated with Bayesian techniques.•An active component is obtained for 20 countries over 1995–2017, including China.•The new approach overcomes the scarce data problem plaguing the existing approach.•The estimates are a better proxy of FX interventions than simple changes in reserves.
Acyclic quaternary carbons by conjugate addition: The first examples of catalytic enantioselective conjugate additions of aryl and alkyl units that generate acyclic all‐carbon quaternary stereogenic ...centers have been developed (see scheme). The requisite organoaluminum reagents can either be prepared in situ from easily available organolithiums or purchased at low cost.
The effective treatment of perianal fistulizing Crohn's disease is still a challenge. Local administration of mesenchymal stromal cells (MSCs) is becoming a part of accepted treatment options. ...However, as a fledgling technique, it still can be optimized. A new trend in translational research, which is in line with "One Health" approach, bases on exploiting parallels between naturally occurring diseases affecting humans and companion animals. Canine anal furunculosis (AF) has been indicated as condition analogous to human perianal Crohn's disease (pCD). This narrative review provides the first comprehensive comparative analysis of these two diseases based on the published data. The paper also outlines the molecular mechanisms of action of MSCs which are likely to have a role in modulating the perianal fistula niche in humans, and refers them to the current knowledge on the immunomodulatory properties of canine MSCs. Generally, the pathogenesis of both diseases shares main determinants such as the presence of genetic predispositions, dysregulation of immune response and the relation to intestine microbiota. However, we also identified many aspects which should be further specified, such as determining the frequency of true fistulas formation in AF patients, elucidating the role of TNF and Th17 pathway in the pathogenesis of AF, or clarifying the role of epithelial-to-mesenchymal transition phenomenon in the formation of canine fistulae. Nevertheless, the available data support the hypothesis that the results from testing cell therapies in dogs with anal furunculosis have a significant translational value in optimizing MSC transplants procedures in pCD patients.
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