Cryptosporidium Log-inactivation with Ozone Using Effluent CT10, Geometric Mean CT10, Extended Integrated CT10 and Extended CSTR Calculations

The draft Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) contains Cryptosporidium log-inactivation CT tables (ozone-in-water concentration [residual], “C” times contact time, T). Depending on water temperature, Cryptosporidium CT values that are listed are 15 to 25 times greater than CT values for equivalent Giardia log-inactivation credit. The elevated operating dose required for Cryptosporidium log-inactivation credit has the potential to increase disinfection by-product (DBP) formation (e.g., bromate). Calculating CT value accurately will minimize ozone dose, which will decrease operating cost and lower DBP formation, and at the same time maintain disinfection protection through implementation of scientifically based safety factors. Various methods are available for calculating CT value. The method chosen depends largely on the available information concerning ozone residual characteristics and hydrodynamic features of the ozone contactor, plus local regulatory requirements. Four methods are discussed in this paper. Each method can be used to calculate Giardia, virus, and Cryptosporidium log-inactivation credit.     

Computer Simulations and Network-Based Profiling of Binding and Allosteric Interactions of SARS-CoV-2 Spike Variant Complexes and the Host Receptor: Dissecting the Mechanistic Effects of the Delta and Omicron Mutations

In this study, we combine all-atom MD simulations and comprehensive mutational scanning of S-RBD complexes with the angiotensin-converting enzyme 2 (ACE2) host receptor in the native form as well as the S-RBD Delta and Omicron variants to (a) examine the differences in the dynamic signatures of the S-RBD complexes and (b) identify the critical binding hotspots and sensitivity of the mutational positions. We also examined the differences in allosteric interactions and communications in the S-RBD complexes for the Delta and Omicron variants. Through the perturbation-based scanning of the allosteric propensities of the SARS-CoV-2 S-RBD residues and dynamics-based network centrality and community analyses, we characterize the global mediating centers in the complexes and the nature of local stabilizing communities. We show that a constellation of mutational sites (G496S, Q498R, N501Y and Y505H) correspond to key binding energy hotspots and also contribute decisively to the key interfacial communities that mediate allosteric communications between S-RBD and ACE2. These Omicron mutations are responsible for both favorable local binding interactions and long-range allosteric interactions, providing key functional centers that mediate the high transmissibility of the virus. At the same time, our results show that other mutational sites could provide a “flexible shield” surrounding the stable community network, thereby allowing the Omicron virus to modulate immune evasion at different epitopes, while protecting the integrity of binding and allosteric interactions in the RBD–ACE2 complexes. This study suggests that the SARS-CoV-2 S protein may exploit the plasticity of the RBD to generate escape mutants, while engaging a small group of functional hotspots to mediate efficient local binding interactions and long-range allosteric communications with ACE2.     

Oxidation with air of cyclohexanone to carboxylic diacids on carbon catalysts

Carbons derived from phenolic resins were used as catalysts for the aqueous phase oxidation of cyclohexanone at 140°C under air pressure. The reaction yielded mainly adipic, glutaric and succinic acids. The samples were modified by heat treatments in CO₂, air or N₂ at different temperatures and characterized to determine their surface area and porosity and to evaluate the functional groups on the surface. Treatments under CO₂ or air increased the oxidation activity. The selectivity to adipic acid was maximum (33%) after activation in air which greatly increased the surface concentration of oxygen-containing functional groups. However, it was not possible to attribute the selectivity to specific acidic, neutral or basic groups present at the surface of carbons. This revised version was published online in June 2006 with corrections to the Cover Date.     

新一代高性能通用型内外墙苯丙乳液

水性乳胶漆的特点是：环保、安全和卓越的性能。乳液作为乳胶漆中非常重要的成分,对乳胶漆的性能有着决定性的作用,高的玻璃化转变温度（Tg）和乳液成膜性是一对矛盾。如何解决？罗门哈斯多年来在涂料行业的经验和技术积累基础上,应用交联技术和采用优化的稳定性配方,开发出新一代的通用型苯丙乳液百历摩^TM（Primal^TM）AS-2010,解决了成膜性与诸多抗性之间的矛盾。     

Three-dimensional microstructural changes in the Ni–YSZ solid oxide fuel cell anode during operation

Microstructural evolution in solid oxide fuel cell (SOFC) cermet anodes has been investigated using X-ray nanotomography along with differential absorption imaging. SOFC anode supports composed of Ni and yttria-stabilized zirconia (YSZ) were subjected to extended operation and selected regions were imaged using a transmission X-ray microscope. X-ray nanotomography provides unique insight into microstructure changes of all three phases (Ni, YSZ, pore) in three spatial dimensions, and its relation to performance degradation. Statistically significant 3D microstructural changes were observed in the anode Ni phase over a range of operational times, including phase size growth and changes in connectivity, interfacial contact area and contiguous triple-phase boundary length. These observations support microstructural evolution correlated to SOFC performance. We find that Ni coarsening is driven by particle curvature as indicated by the dihedral angles between the Ni, YSZ and pore phases, and hypothesize that growth occurs primarily by means of diffusion and particle agglomeration constrained by a pinning mechanism related to the YSZ phase. The decrease in Ni phase size after extended periods of time may be the result of a second process connected to a mobility-induced decrease in the YSZ phase size or non-uniform curvature resulting in a net decrease in Ni phase size.     

Sorbent injection into a slipstream baghouse for mercury control: Project summary

A project led by the Energy and Environmental Research Center to test and demonstrate sorbent injection as a cost-effective mercury control technology for utilities burning lignites has shown effective mercury capture under a range of operating conditions. Screening, parametric, and long-term tests were carried out at a slipstream facility representing an electrostatic precipitator–activated carbon injection–fabric filter configuration (called a TOXECON™ in the United States). Screening tests of sorbent injection evaluated nine different sorbents, including both treated and standard activated carbon, to compare mercury capture as a function of sorbent injection rate. Parametric tests evaluated several variables including air-to-cloth (A/C) ratio, flue gas temperature, cleaning frequency, and dust loading to determine the effect on mercury control and systems operation. Long-term tests (approximately 2 months in duration) evaluated the sustainability of systems operation.     

Controlled oxidation of hydrocarbons by the membrane-bound methane monooxygenase: the case for a tricopper cluster

[Figure: see text]. The growing need for inexpensive methods to convert methane to methanol has sparked considerable interest in methods that catalyze this process. The integral membrane protein particulate methane monooxygenase (pMMO) mediates the facile conversion of methane to methanol in methanotrophic bacteria. Most evidence indicates that pMMO is a multicopper enzyme, and these copper ions support redox, dioxygen, and oxo-transfer chemistry. However, the exact identity of the copper species that mediates the oxo-transfer chemistry remains an area of intense debate. This highly complex enzyme is notoriously difficult to purify because of its instability outside the lipid bilayer and tendency to lose its essential metal cofactors. For this reason, pMMO has resisted both initial identification and subsequent isolation and purification for biochemical and biophysical characterization. In this Account, we describe evidence that pMMO is a multicopper protein. Its unique trinuclear copper cluster mediates dioxygen chemistry and O-atom transfer during alkane hydroxylation. Although a recent crystal structure did not show this tricopper cluster, we provide compelling evidence for such a cluster through redox potentiometry and EPR experiments on the "holo" enzyme in pMMO-enriched membranes. We also identify a site in the structure of pMMO that could accommodate this cluster. A hydrophobic pocket capable of harboring pentane, the enzyme's largest known substrate, lies adjacent to this site. In addition, we have designed and synthesized model tricopper clusters to provide further chemical evidence that a tricopper cluster mediates the enzyme's oxo-transfer chemistry. These biomimetic models exhibit similar spectroscopic properties and chemical reactivity to the putative tricopper cluster in pMMO. Based on computational analysis using density functional theory (DFT), triangular tricopper clusters are capable of harnessing a "singlet oxene" upon activation by dioxygen. An oxygen atom is then inserted via a concerted process into the C-H bond of an alkane in the transition state during hydroxylation. The turnover frequency and kinetic isotope effect predicted by DFT show excellent agreement with experimental data.     

Electrochemical behavior of Ge and GeX2 (X = O, S) glasses: Improved reversibility of the reaction of Li with Ge in a sulfide medium

Sulfide glasses have been considered as new anode materials for lithium-ion batteries because their high ionic conductivity (approximately ≥10⁻⁴ S/cm) (more than one order of magnitude higher than oxide glasses (approximately ≤10⁻⁶ S/cm)) was expected to accelerate Li⁺ ion insertion into and extraction from anode materials during charge and discharge reactions. This intrinsic property can yield the reversible lithium-alloying reaction by minimizing the aggregation of lithium-alloy phases leading to the improvement of cycling behavior. To examine sulfide glasses as new anode materials, GeS₂ glass was chosen for study in this work due to its stability in air-atmospheres. The electrochemical properties of the GeS₂ glass were compared with those of the Ge metal and GeO₂ glass. The initial insertion of lithium into the GeX₂ (X = O, S) glasses leads to the formation of Li₂X (X = O, S) phases associated with the irreversible capacity on the first cycle. The improved reversibility of the reaction of lithium with Ge was observed in the Li₂S medium rather than Li₂O one, which leads to the improvement of cycle performance in the GeS₂ glass anode.     

Changing perceptions of hunger on a high nutrient density diet

Background  

People overeat because their hunger directs them to consume more calories than they require. The purpose of this study was to analyze the changes in experience and perception of hunger before and after participants shifted from their previous usual diet to a high nutrient density diet.