Designing zeolite catalysts for shape-selective reactions: Chemical modification of surfaces for improved selectivity to dimethylamine in synthesis from methanol and ammonia

The relative contributions of external and intracrystalline acidic sites of small pore H-RHO zeolite for the selective synthesis of methylamines from methanol and ammonia have been studied. Nonselective surface reactions which produce predominantly trimethylamine can be eliminated by “capping” the external acidic sites with trimethylphosphite (TMP) and other reagents, thus improving the selectivity toward the formation of dimethylamine. For small pore zeolites, neither the zeolite pore size nor the internal acidic sites is significantly affected by this treatment. In situ infrared and MAS-NMR studies show that TMP reacts irreversibly with the zeolite acidic sites via a modified Arbusov rearrangement to form surface-bound dimethylmethylphosphonate

Metal Recovery Using Oxalate Chemistry: A Technical Review

Energy-efficient metal recovery and separation processes from a mixture of valuable metals are vital to the metallurgy and recycling industries. Oxalate has been identified as a sustainable reagent that can provide both the desired selectivity and efficient leaching capabilities for a variety of mixed metals under mild reaction conditions. The oxalate process has a great potential to replace many of the existing metal recovery processes that use inorganic acids such as sulfuric, hydrochloric, and nitric acids. In this Review, the use of oxalate chemistry in four major metal recovery applications is discussed, namely, spent lithium-ion batteries, spent catalysts, valuable ores, and contaminated and unwanted waste streams. Recycling of critical and precious metals from spent lithium-ion batteries and catalysts has significant economic opportunities. For efficient metals recovery, reaction conditions (e.g., temperature, pH, time, and concentration), metal–oxalate complex formation, oxidation and reduction, and metal precipitation must all be well-understood. This Review provides an overview from articles and patents for a variety of metal recovery processes along with insights into future process development

Relaxed Genetic Constraint is Ancestral to the Evolution of Phenotypic Plasticity

Phenotypic plasticity––the capacity of a single genotype to produce different phenotypes in response to varying environmental conditions––is widespread. Yet, whether, and how, plasticity impacts evolutionary diversification is unclear. According to a widely discussed hypothesis, plasticity promotes rapid evolution because genes expressed differentially across different environments (i.e., genes with “biased” expression) experience relaxed genetic constraint and thereby accumulate variation faster than do genes with unbiased expression. Indeed, empirical studies confirm that biased genes evolve faster than unbiased genes in the same genome. An alternative hypothesis holds, however, that the relaxed constraint and faster evolutionary rates of biased genes may be a precondition for, rather than a consequence of, plasticity’s evolution. Here, we evaluated these alternative hypotheses by characterizing evolutionary rates of biased and unbiased genes in two species of frogs that exhibit a striking form of phenotypic plasticity. We also characterized orthologs of these genes in four species of frogs that had diverged from the two plastic species before the plasticity evolved. We found that the faster evolutionary rates of biased genes predated the evolution of the plasticity. Furthermore, biased genes showed greater expression variance than did unbiased genes, suggesting that they may be more dispensable. Phenotypic plasticity may therefore evolve when dispensable genes are co-opted for novel function in environmentally induced phenotypes. Thus, relaxed genetic constraint may be a cause––not a consequence––of the evolution of phenotypic plasticity, and thereby contribute to the evolution of novel traits

Development of Silica-Immobilized Vaccines for Improving Thermo-Tolerance and Shelf-Life

Introduction. It is estimated that 50% of vaccines produced annu- ally are wasted because effectivity is dependent on protein structure and heat exposure disrupts the intermolecular interactions that maintain this structure. Since 90% of vaccines require a temperature- controlled supply chain, it is necessary to create a cold chain system to minimize vaccine waste. We have developed a more sustainable technology via the adsorption of Invasion Plasmid Antigen D (IpaD) onto mesoporous silica gels, improving the thermal stability of pro- tein-based therapeutics. Methods.xThe solution depletion method using UV-Vis was uti- lized to study the adsorption of IpaD onto silica gels. The silica-IpaD complex is heated above the denaturing temperature of the protein and then the IpaD is removed using N,N-Dimethyldodecylamine N-oxide (LDAO) and their secondary structure is tested using cir- cular dichroism (CD). Results. Pore diameter, pore volume and surface area were charac- terized for seven different silica gels. Silica gels designated as 6389, 6378, and 6375 had an adsorption percentage above 95% at pore volumes of 2.2, 2.8 and 3.8 cm3 mg-1, respectively. CD analyses con- firmed that the adsorbed IpaD after the heat treatment displayed a similar “W” shape CD signal as the native IpaD, indicating the con- servation of α-helices. In contrast, the unprotected IpaD after being exposed to high temperature shows a flat CD signal, demonstrating the loss of secondary structure. Conclusion. We have successfully increased the thermo-tolerance for IpaD using mesoporous silica and continue to further optimize mesoporous silica’s physiochemical properties to improve adsorption and desorption yields

From sulphur to perfume: spa and SPA at Monchique, Algarve

In the thermal village of Monchique, Algarve, different streams of water-related knowledge and practices coexisted for centuries. Those waters were traditionally known as águas santas (holy waters) and believed to have redemptive healing powers. In the seventeenth century, the Catholic church took control of the place, refashioned the bathing rituals, developed infrastructures and provided assistance to the patients, granting free treatment to the poor. In the nineteenth century, the state replaced the church and imposed that treatments should be provided by professionals trained in the scientific principles of medical hydrology. Secular and scientific as they were, clinical logbooks still allowed for the account of patients that embodied miracle-like redemptive cures ‘at the third bath’. People went to Monchique both for its magic and its medicine, bringing in the body ailments achieved in their lives of hard labour. They also went there for a socialising break while healing. From mendicants to rich landowners, coming mostly from the Algarve and neighbouring Alentejo, they crowded the place in summertime. In the twentieth century, as in other places in continental Europe, the spa evolved into a highly medicalised place that qualified for medical expenses reimbursements, which implied the eclipsing – at least from representation – of its leisure component. In the twenty-first century, a new trend of consumer-centred, market-based, post-water balneology with an emphasis on wellness and leisure reinvented the spa as place for lush and diversified consumption. This article argues that the seemingly contradictory systems (markets and medicine) coexist much in the same way that magic, religion and medicine coexisted in the old water sites. The new SPAs, rather than putting an end to the old spas, have enabled them to survive by reinventing thermal sites as places of attraction and leisure

Fungal iron availability during deep seated candidiasis is defined by a complex interplay involving systemic and local events

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