Formation of the bubble structure in the 26Li<Subscript>2</Subscript>O · 74SiO<Subscript>2</Subscript> glass

The formation of a bubble structure in the glass of composition 26Li₂O · 74SiO₂ is investigated. The stable reproducible characteristics of the bubble structure are obtained, namely, dependences of the number of bubbles on the conditions of glass synthesis, i.e., the synthesis temperature, the synthesis time, and the type of initial reagents. It is shown that the number of bubbles decreases with an increase in the height of the sample (glass melt in the crucible), as well as with an increase in the synthesis temperature at a fixed synthesis time or with an increase in the synthesis time for each specific temperature. The bubble size distribution curves are obtained for all synthesis conditions. The reproducible bubble structure is determined for each layer of the glass sample, which is subsequently used in studying the kinetics of heterogeneous nucleation.     

Influence of the presence of bubbles on the parameters of crystal nucleation in the 26Li<Subscript>2</Subscript>O · 74SiO<Subscript>2</Subscript> glass

The crystal nucleation in the glass of composition (mol %) 26Li₂O · 74SiO₂ has been investigated in the cases of homogeneous and heterogeneous nucleation. Parameters of homogeneous nucleation, such as the stationary nucleation rate I _st, the time of nonstationary nucleation τ, and the crystal growth rate U, have been determined. The temperature dependences of these parameters have been constructed. The surface energy σ at the nucleus-glass melt interface has been determined, and its temperature dependence has been obtained. The surface energy σ has been evaluated using the graphical method for solving the transcendental equation derived by transforming the relationships for the stationary crystal nucleation rate and the time of nonstationary crystal nucleation. The critical nucleus sizes r* and the free energy of formation of the critical nucleus Φ* have been determined. The heterogeneous nucleation on bubbles specially produced in the glass has been studied. It has been demonstrated that the presence of bubbles in the initial glass does not affect the crystal growth rate and substantially changes the nonstationary nucleation rate. The largest contribution to the change in the nucleation rate is made by “active” bubbles (filled by water vapor) formed in the glasses synthesized with the use of hydrated silicon dioxide.     

Market Basket Analysis: A New Tool in Ecology to Describe Chemical Relations in the Environment—A Case Study of the Fern <Emphasis Type="Italic">Athyrium distentifolium</Emphasis> in the Tatra National Park in Poland

In this study, the novel data mining technique Market Basket Analysis (MBA) was applied for the first time in biogeochemical and ecological investigations. The method was tested on the fern Athyrium distentifolium, in which we measured concentrations of the elements Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn. Plants were sampled from sites with different types of bedrock in the Tatra National Park in Poland. MBA was used to investigate whether specimens of Athyrium distentifolium that contain elevated levels of certain elements occur more frequently on a specific type of bedrock and to identify relationships between the type of bedrock and the concentrations of the elements in this fern. The results were compared with those of the commonly used principal component and classification analysis (PCCA) technique. MBA and PCCA ordination both yielded distinct groups of ferns growing on different types of bedrock. Although the results of MBA and PCCA were similar, MBA has the advantage of being independent of the size of the data set. In addition, MBA revealed not only dominant elements but, in the case of limestone bedrock, also showed very low concentrations of Cd, Fe, Mn, and Pb in ferns growing on this type of parent material. MBA, thus, appeared to be a promising data mining method to reveal chemical relations in the environment as well as the accumulation of chemical elements in bioindicators. This technique can be used to reveal associations and correlations among items in large data sets collected on a national or even larger scale.     

Immunotherapy in Advanced Prostate Cancer—Light at the End of the Tunnel?

Immunotherapeutic treatment approaches are now an integral part of the treatment of many solid tumors. However, attempts to integrate immunotherapy into the treatment of prostate cancer have been disappointing so far. This is due to a highly immunosuppressive, “cold” tumor microenvironment, which is characterized, for example, by the absence of cytotoxic T cells, an increased number of myeloid-derived suppressor cells or regulatory T cells, a decreased number of tumor antigens, or a defect in antigen presentation. The consequence is a reduced efficacy of many established immunotherapeutic treatments such as checkpoint inhibitors. However, a growing understanding of the underlying mechanisms of tumor–immune system interactions raises hopes that immunotherapeutic strategies can be optimized in the future. The aim of this review is to provide an overview of the current status and future directions of immunotherapy development in prostate cancer. Background information on immune response and tumor microenvironment will help to better understand current therapeutic strategies under preclinical and clinical development.     

Si-filled ceramic composite by thermal explosion in the Al–SiO<Subscript>2</Subscript> system

Si-filled ceramic composite was prepared through thermal explosion in the Al–SiO₂ system. The material can be expected to find its application to reprocessing quartz wastes into cermets to be used in microelectronic devices.     

The Treatment of Dyslipidemia—What's Left in the Pipeline?

Dyslipidemia is a pathological alteration of serum lipid levels. The most common forms are either elevations of triglycerides or low density lipoprotein cholesterol associated with a reduction of high density lipoprotein cholesterol. Most frequently both forms of lipid disorders are combined. Elevations of free fatty acid blood levels are commonly not subsumed under the term dyslipidemia. However, free fatty acids should also be considered, as they are frequently associated with dyslipidemia and represent a risk factor for cardiovascular diseases. Dyslipidemias are among the major etiologic factors for arterial occlusive diseases. Resulting in fatal implications such as stroke and coronary heart disease, dyslipidemias contribute to the most prevalent causes of death. Lowering of low density lipoprotein and raising of high density lipoprotein cholesterol levels have been shown in both epidemiologic and intervention studies to decrease mortality. Established treatments of dyslipidemias are statins and fibrates. However, recent research has established some new potential therapeutic targets which are currently investigated in clinical trials. New therapeutic approaches include subtype selective, dual, and pan-agonists of the peroxisome proliferator activated receptor, inhibitors of the cholesterol ester transfer protein, Acyl-CoA-cholesterol-acyltransferase, squalene synthase, microsomal triglycerid-transfer-protein, and cholesterol absorption. Clinical implications of new drugs under investigation are discussed in this review.     

Reductive amination of monoethanolamine in the presence of the NiCo/BPO<Subscript>4</Subscript> · γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst: Process optimization based on a mathematical model and calculation of the basic design parameters of the reactor

Based on experimental kinetic data for the reductive amination of monoethanolamine in the presence of the NiCo/BPO₄ · γ-Al₂O₃ catalyst, a mechanism of this process is suggested and the corresponding kinetic model is constructed. A mathematical model of the reactor process is developed, and this model is used to solve three process optimization problems. Optimal values of operating parameters are found, and these values are used in the calculation of basic dimensions of a commercial-scale reactor. The flexible process design suggested allows all of the three process variants corresponding to the three optimization problems to be carried out.     

Scheloribatid Mites as the Source of Pumiliotoxins in Dendrobatid Frogs<Superscript>†</Superscript>

The strawberry poison frog Dendrobates pumilio (Anura: Dendrobatidae) and related poison frogs contain a variety of dendrobatid alkaloids that are considered to be sequestered through the consumption of alkaloid-containing arthropods microsympatrically distributed in the habitat. In addition to ants, beetles, and millipedes, we found that adults of two species of oribatid mites belonging to the cohort Brachypylina, trophically a lower level of animal than ants and beetles, contain dendrobatid alkaloids. Gas chromatography/mass spectrometry (GC/MS) of hexane extracts of adult Scheloribates azumaensis (Oribatida: Acari) revealed the presence of not only pumiliotoxin 251D (8-hydroxy-8-methyl-6-(2′-methylhexylidene)-1-azabicyclo[4.3.0]nonane), but also precoccinelline 193C and another coccinelline-type alkaloid. From the corresponding extracts of an unidentified Scheloribates sp., pumiliotoxin 237A (8-hydroxy-8-methyl-6-(2′-methylpentylidene)-1-azabicyclo[4.3.0]nonane) was detected as a minor component, and identified by synthesis. The presence of related alkaloids, namely deoxypumiliotoxin 193H, a 6,8-diethyl-5-propenylindolizidine, and tentatively, a 1-ethyl-4-pentenynylquinolizidine, were indicated by the GC/MS fragmentation patterns, along with at least another six unidentified alkaloid components. Thus, one possible origin of pumiliotoxins, coccinellid alkaloids, and certain izidines found in poison frogs may be mites of the genus Scheloribates and perhaps related genera in the suborder Oribatida. Chemical Ecology of Oribatid Mites IV.     

A glucose derivative as natural alternative to the cyclohexane‐1,2‐diamine ligand in the anticancer drug oxaliplatin?

Having oxaliplatin as archetype, several platinum complexes with a carbohydrate moiety resembling the cyclohexane-1,2-diamine ligand of oxaliplatin have been prepared. As leaving groups, the anionic ligands iodide, oxalate, and malonate were utilized, and for comparison purposes the chloro complex was employed. All compounds were characterized by elemental analysis, nuclear magnetic resonance spectroscopy, and electrospray mass spectrometry. The crystal structure of (SP-4-3)-diiodo(2,3-diamino-2,3-dideoxy-D-glucose-kappa(2)N,N')platinum(II) was determined by X-ray diffraction. The affinity toward dGMP was assayed by capillary electrophoresis, revealing that the chloro complex shows the highest reactivity, followed by the iodo complex. In contrast, the binding kinetics of the dicarboxylato complexes are slower, with the malonato complex being the least reactive. Reactivity to dGMP in the cell-free system correlates with cytotoxicity in two of four human cancer cell lines as determined by means of the MTT assay. In three of the four cell lines, the chloro and the malonato complex are the most and the least active of the carbohydrate-Pt complexes, respectively, with IC(50) values differing only by factors of up to 3.2. Cytotoxicity of the chloro complex is one to two orders of magnitude lower than that of oxaliplatin, but still comparable to that of carboplatin in two of the four cell lines.     

KLK3 in the Regulation of Angiogenesis—Tumorigenic or Not?

In this focused review, we address the role of the kallikrein-related peptidase 3 (KLK3), also known as prostate-specific antigen (PSA), in the regulation of angiogenesis. Early studies suggest that KLK3 is able to inhibit angiogenic processes, which is most likely dependent on its proteolytic activity. However, more recent evidence suggests that KLK3 may also have an opposite role, mediated by the ability of KLK3 to activate the (lymph)angiogenic vascular endothelial growth factors VEGF-C and VEGF-D, further discussed in the review.     

Evidence of multi-component interaction in a V–Ce–HUSY catalyst: Is the cerium–EFAL interaction the key of vanadium trapping?

Cerium was introduced into a USY-based catalyst using three methodologies: precipitation, impregnation and ionic-exchange. The CeUSY catalysts were poisoned with vanadium and deactivated with steam at 1073 K. The catalysts were characterized by HRTEM-EDX, FTIR, BET, EPR, XPS and by the test of catalytic dehydration of 2-propanol. The results indicate that the presence of a V–Ce–EFAL multi-component interaction strongly affects the vanadium reduction and its migration, also inhibiting the cerium oxide sintering. HRTEM measurements with analysis of energy dispersive X-rays on the impregnated catalyst revealed a preferential V–Ce interaction in the extra framework aluminum (EFAL) domains. The FTIR results strongly support that this V–Ce–EFAL interaction occurs via hydroxyl groups. The impregnated catalysts showed greater vanadium tolerance than catalysts prepared by other methodologies of cerium introduction.     

Negative Effects of CO<Subscript>2</Subscript> in the Feed Stream on the Catalytic Performance of Precipitated Iron-Based Catalysts for Fischer–Tropsch Synthesis

Abstract  

Fischer–Tropsch synthesis was carried out over precipitated iron-based catalysts with different amounts of CO₂ in the feed stream while maintaining both total reaction pressure (1.5 MPa) and partial pressure of H₂ + CO (0.75 MPa) using an inert balance gas, N₂. The CO₂ in the feed stream decreased the rate of hydrocarbon formation, but it had no significant influence on the carbon number distribution of hydrocarbons. The CO₂ in the feed stream also suppressed CO₂ formation, decreasing both CO conversion and CO₂ selectivity. We attribute the decreased reaction rate to the partial competition in the adsorption behavior between CO and CO₂ as revealed in the temperature-programmed desorption.     

Reassessment of the Identity of the Blue Light Emitter in Copper‐Containing Pyrotechnic Flames – Is it really CuCl?

While it is commonly thought that the molecular species responsible for the emission of blue light in fireworks flames is CuCl, a review of the physicochemical data obtained on gaseous CuCl vapors indicates that the actual emitter is the trimer Cu₃Cl₃. The literature is reviewed with regard to this issue, and a few experiments which might resolve the question are proposed.     

SHS of α-Si<Subscript>3</Subscript>N<Subscript>4</Subscript> from fine Si powders in the presence of blowing agents

Explored was the effect of blowing agent (NH₄Cl + NH₄F mixtures) on the SHS of α-Si₃N₄ from a mixture of fine Si powder and α-Si₃N₄ used as an inert diluent. A prerequisite for a maximal specific surface of resultant Si₃N₄ powder was found to be perfect homogenization of starting Si-Si3N4 mixtures.     

Analysis of the Parameters of the Mössbauer Spectra and the Spectra of Nuclear Quadrupole Resonance of the Superconducting Ceramic YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7</Subscript>

The parameters of the Mössbauer spectra on ⁶⁷Cu(⁶⁷Zn), ⁶⁷Ga(⁶⁷Zn) isotopes, and the data of nuclear quadrupole resonance on an ¹⁷O isotope are anlayzed, and the lattice gradient of the electric field for the crystal lattice YBa₂Cu₃O₇ is calculated. It is shown that these parameters correspond to the model when the hole is predominantly in the sublattice of the oxygen chain.     

α-Amylase Mediates Host Acceptance in the Braconid Parasitoid <Emphasis Type="Italic">Cotesia flavipes</Emphasis>

Foraging parasitoids use chemical signals in host recognition and selection processes. Although, the volatiles play a relevant role in the localization by parasitoids of their hosts feeding on plants, the host identification process for acceptance occurs mainly during contact between the parasitoid and its host where host products related to feeding activities, fecal pellets and oral secretions, play a crucial role. The purpose of this study was to identify the nature of the contact kairomone(s) that mediate the acceptance for oviposition of the parasitoid Cotesia flavipes Cameron (Hymenoptera, Braconidae), which was released in Kenya in 1993 to control the invasive crambid Chilo partellus (Swinhoe). Using host and non-hosts of C. flavipes, we showed that it is mainly the oral secretions of the larvae that harbour the active compound(s) that mediate host acceptance for oviposition by C. flavipes. Using an integration of behavioral observations and biochemical approaches, the active compound of the oral secretions was identified as an α-amylase. Using synthetized α-amylases from Drosophila melanogaster (an insect model for which syntheses of active and inactive α-amylases are available), we observed that the conformation of the enzyme rather than its catalytic site as well as its substrate and its degradation product is responsible for host acceptance and oviposition mediation of C. flavipes females. The results suggest that the α-amylase from oral secretions of the caterpillar host is a good candidate for an evolutionary solution to host acceptance for oviposition in C. flavipes.     

Deactivation control through accelerated precoking for the CoMo/γAl<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts in thiophene hydrodesulfurization

Information on the degree of deactivation is very important for predicting catalyst life, from which the catalyst design could be further improved. The CoMo/Al₂O₃ catalysts, used for the hydrodesulfurization of light oil, are known to have a commercial operation time of around two years. Our goal was to establish the accelerated precoking conditions for obtaining a desired degree of deactivation for CoMo/Al₂O₃ catalysts. The effect of coking temperature on the catalytic activity for thiophene hydrodesulfurization was investigated for three coke precursors. Precoking with heavier precursors resulted in higher coke content and higher aromaticity as expected, i.e., in order of anthracene>naphthalene>cyclohexene. It is suggested that the established conditions of precoking for the commercial catalysts could provide a quantitive reference for evaluating the lifetime of any commercial catalysts.     

Phase relationships in the Na<Subscript>2</Subscript>ZnP<Subscript>2</Subscript>O<Subscript>7</Subscript>–LiKZnP<Subscript>2</Subscript>O<Subscript>7</Subscript> system

The phase relationships in the Na₂ZnP₂O₇–LiKZnP₂O₇ system are studied. They are represented by a mixture of the starting components in the subsolidus region. The eutectic was found at a temperature of 640°C and composition of 0.5LiKZnP₂O₇. The phase formation of this system is compared with the previously studied NaKZnP₂O₇–LiKZnP₂O₇ system. It is shown that a structural factor affects the geometry of the state diagrams.     

Identification of Δ<Superscript>7</Superscript> phytosterols and phytosteryl glucosides in the wood and bark of several <Emphasis Type="Italic">Acacia</Emphasis> speciesphytosterols and phytosteryl glucosides in the wood and bark of several <Emphasis Type="Italic">Acacia</Emphasis> species

The wood and bark of four Acacia species growing in Portugal, namely, A. longifolia, A. dealbata, A. melanoxylon, and A. retinodes, were investigated for their sterol content. The lipids fractions of the different wood and bark samples were isolated, and the sterols were identified and quantified by GC-MS. Two Δ⁷ sterols, specifically, spinasterol and dihydrospinasterol, were the main sterols found in considerable amounts, particularly in wood tissues (more than 0.5 g/kg of dry wood in the case of A. melanoxylon and A. retinodes). The corresponding unusual steryl glucosides were also identified in significant amounts in the wood and bark extracts.