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Molina, Natalia. A place at the Nayarit: how a Mexican restaurant nourished a community. California, 2022. 312p bibl index ISBN 9780520385481 cloth, $29.95; ISBN 9780520385498 pbk, $29.95 (cc)60-0911 TX909 CIP [...]

Rare earth elements (REE) play an integral part of modern life, from smartphones to satellites. Dubbed ‘critical metals’, the demand for REE has significantly increased, driven by the growth in global production for green technologies such as e-vehicles, solar panels, wind turbines, and other energy-economic infrastructure. Therefore, there is a need to explore alternative REE sources to ensure continued development of emerging green technologies. A possible alternative REE source is bauxite, which is soil that forms from intense weathering of aluminum oxide-rich rocks exposed to tropical climate. This paper investigates the REE enrichment and extraction potential from bauxite deposits in Paranas, Samar, Philippines. The sampling survey included collection of rock and soil on surface exposures, test pits, and drill cores from accessible portions of the bauxite mineral reservation site. The soil and parent rock samples collected were then subjected to various geochemical and mineralogical analyses. The main ore minerals of aluminum are gibbsite and boehmite; with minor goethite, hematite, and magnetite. Investigation of the geochemical composition of the bauxite reveals a total REE content of up to ~300 ppm, which is one of the highest REE and critical metal content among geological deposits in the country. These results will provide inputs in the design of a green and economical process to recover REE from bauxites. If the bauxite deposits prove to be a valuable REE resource, this study will help maximize the economic potential of the mineral resource in the Philippines and contribute to an economically efficient and environment-friendly way to produce e-tech elements for the country.

ABSTRACTRacket sports such as padel are characterised by a variety of specific displacements and behaviours on the court with the aim to cover spaces and take an offensive advantage during the point. The aim of this study was to analyse players’ location in offensive position when opponent hits the ball in different defensive zones. The sample included nine matches from a total of three top national indoor padel tournaments. Twenty-four male padel players performed the matches. Players and ball position was registered using a computerised motion tracking video system. Results showed a significant relation between offensive players’ movements (forward, backward or sideways) according to the position of the ball in defensive zones. Heat map and statistics analysis showed that regarding players’ width positioning, when the ball is in one corner of the defensive zone, both offensive players move to that side of the court. However, regarding players’ depth positioning, if one offensive player moves close to the net, his partner moves some metres back. Such knowledge may constitute a very important factor affecting tactic and task design for padel players and coaches and could be used as an important reference for others ball-over-net sports such as doubles tennis, doubles badminton, beach tennis or volleyball.

Idiopathic bronchiolitis obliterans organizing pneumonia (BOOP)[1,2] or cryptogenic organizing pneumonia[3] is a clinicopathologic entity of unknown origin characterized by the following: (1) the clinical presentation with a preceding flu-like illness [...]

Community-based participatory research (CBPR) is widely recognized as an effective approach to understand and address health inequities. Opportunities for public health practitioners and researchers to engage jointly with community partners in intensive colearning processes can build capacity for CBPR. Using active learning approaches that engage diverse partners can enhance partnership development, competence, and equity. Examination of such pedagogical approaches can strengthen understanding of their contributions to the effectiveness of CBPR capacity-building programs. This article describes a weeklong intensive course carried out by the Detroit Urban Research Center as the foundation for a yearlong training program to build the capacity of community-academic partnership teams to engage in CBPR in their own communities. The in-person CBPR course was developed and implemented by expert academic and community instructors and used an experiential action learning model that integrated CBPR principles and processes. We describe the course content and application of our collaborative, experiential action learning model to course design; present results from participant evaluation of course effectiveness, CBPR competence, and equitable partnership development; and examine the contributions of the pedagogical approach to outcomes central to successful CBPR. The participatory, formative course evaluation used multiple methods that included closed- and open-ended questionnaires to assess instructional effectiveness, participant competence on 12 core components of CBPR, and course impact on partner relationships. Evaluation findings suggest that an experiential action learning approach with attention to colearning, collaboration among diverse instructors and participants, and an environment that fosters and models equitable and trusting relationships can be effective in building CBPR capacity.

This paper proposes a simple solution for the stabilization of a mini-quadcopter carrying a 3DoF (degrees of freedom) manipulator robot in order to enhance its achievable workspace and application profile. Since the motion of the arm induces torques which degrade the stability of the system, in the present work, we consider the stabilization of both subsystems: the quadcopter and the robotic arm. The mathematical model of the system is based on quaternions. Likewise, an attitude control law consisting of a bounded quaternion-based feedback stabilizes the quadcopter to a desired attitude while the arm is evolving. The next stage is the translational dynamics which is simplified for control (nonlinear) design purposes. The aforementioned controllers are based on saturation functions whose stability is explicitly proved in the Lyapunov sense. Finally, experimental results and a statistical study validate the proposed control strategy.

Splenogonadal fusion is a rare entity found predominantly in males and often asymptomatic or mildly symptomatic. Here we report a case of symptomatic splenogonadal fusion in a female. She presented with abdominal pain and was found to have splenic torsion that required operative detorsion and partial splenectomy. We further review outcomes and prognosis of this benign condition in males which suggest that the abnormal ovary should be preserved in females with this rare anomaly.

La prueba de oro para el diagnóstico de la neumonía secundaria a Mycoplama pneumoniaees la detección de IgM en pruebas seriadas, ya que una prueba aislada para IgM tiene una sensibilidad del 31,8%. Al existir un cuadro clínico diferenciable de la neumonía por M. pneumoniaede otras etiologías es posible realizar un scoreclínico para su diagnóstico temprano.

C5 nerve root palsy is a rare and potentially debilitating complication of cervical spine surgery. Currently, however, there are no guidelines to help surgeons to prevent or treat this complication.We carried out a systematic review of the literature to identify the causes of this complication and options for its prevention and treatment. Searches of PubMed, Embase and Medline yielded 60 articles for inclusion, most of which addressed C5 palsy as a complication of surgery. Although many possible causes were given, most authors supported posterior migration of the spinal cord with tethering of the nerve root as being the most likely.Early detection and prevention of a C5 nerve root palsy using neurophysiological monitoring and variations in surgical technique show promise by allowing surgeons to minimise or prevent the incidence of C5 palsy. Conservative treatment is the current treatment of choice; most patients make a full recovery within two years.Cite this article: Bone Joint J2014;96-B:950–5.

Hydrologic, watershed, water resources, and climate‐related research conducted by the USDA–ARS Grazinglands Research Laboratory (GRL) are rooted in events dating back to the 1930s. In 1960, the 2927‐km2Southern Great Plains Research Watershed (SGPRW) was established to study the effectiveness of USDA flood control and soil erosion prevention programs. The size of the SGPRW was scaled back in 1978, leaving only the 610‐km2Little Washita River Experimental Watershed (LWREW) to be used as an outdoor hydrologic research laboratory. Since 1978, the number of measurement sites and types of instruments used to collect meteorologic and soil climate data have changed on the LWREW. Moreover, a second research watershed, the 786‐km2Fort Cobb Reservoir Experimental Watershed (FCREW), was added in 2004 to the GRL's outdoor research laboratories to further study the effects of agricultural conservation practices on selected environmental endpoints. We describe the SGPREW, FCREW, and LWREW and the meteorologic measurement network (historic and present) deployed on them, provide descriptions of measurements, including information on accuracy and calibration, quality assurance measures (where known), and data archiving of the present network, give examples of data products and applications, and provide information for the public and research communities regarding access and availability of both the historic and recent data from these watersheds.

Climate variability, changing land use and management, and dynamic policy environments are the main reasons why long‐term research is needed to understand and predict possible water quality outcomes to alternative future scenarios. Long‐term water quality data sets are needed to address these water issues. Such data sets were acquired by the USDA–ARS in three watersheds in Oklahoma: the Southern Great Plains Research Watershed (SGPRW), the Little Washita River Experimental Watershed (LWREW), and the Fort Cobb Reservoir Experimental Watershed (FCREW). We provide: (i) a description of these water quality data sets, (ii) the sample collection and processing procedures used and an assessment of the data quality, (iii) summary analyses of the variability in each data set, and (iv) details about how to access these data sets. Water quality data collection in the SGPRW began in the 1960s and continued through 1978, while that in the LWREW covered the 1960s to 1990 period. Data collection began in the FCREW in 2004 and continues through the present. The data were collected from streams, unit source watersheds, groundwater wells, and reservoirs. The water quality data described for a given site are generally complete for a given period of record; however, not all sites were monitored continuously and were not necessarily analyzed for the same water quality parameters. These data sets are expected to improve modeling and assessments of conservation practices in relation to climate variability, land use changes, and other environmental factors and may be useful in developing strategies to mitigate these environmental impacts.

It is essential to understand sediment and nutrient sources and their spatial and temporal patterns to design effective mitigation strategies. However, long‐term data sets to determine sediment and nutrient loadings are scarce and expensive to collect. The goal of this study was to determine seasonal patterns of suspended sediment (SS), total N (TN), and total P (TP) concentrations and loadings for three USGS gauge sites located at the Fort Cobb Reservoir Experimental watershed (FCREW) located in southwestern Oklahoma. Measured instantaneous discharge, SS, TN, and TP concentration data were used to develop lognormal water quality–discharge relationships. The water quality–discharge relationships were used to generate estimated seasonal concentrations and loads based on hourly or 30‐min interval discharge. The estimated concentrations and loads were used to determine seasonal patterns for SS, TN, and TP relative to the respective state water quality criteria. Decreasing and increasing monotonic trends were observed for the seasonal time series loads for all three sites, but they were insignificant based on the Spearman test (α = 0.05). The largest loads were estimated during the wet springs and summers. The study SS, TN, and TP target concentrations were exceeded in one season or another. The study results showed that the priority locations to implement the TN and TP conservation practices were the Lake Creek and Willow Creek subwatersheds during the winter and spring seasons. Common practices to mitigate nutrients and suspended sediments include nutrient management, no‐till, conversion of cultivated land to pasture, riparian buffers, and animal exclusion.

The increase in the therapeutic arsenal in the last 20 years, has given rise to changes in treating colorectal cancer (CRC) with only pyrimidines to combine several cytotoxic drugs. However, the present question is to determine the optimal sequence of this combination. This review presents an update of data on chemical and clinical features of chemotherapy used for colorectal cancer and the mechanisms of cellular resistance and potential predictive and prognostic biomarkers, which may contribute to a better selection of a therapeutic strategy.

Objective.Granulomatosis with polyangiitis (Wegener’s; GPA) and other antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are rare in childhood and are sometimes difficult to discriminate. We compared use of adult-derived classification schemes for GPA against validated pediatric criteria in the ARChiVe (A Registry for Childhood Vasculitis e-entry) cohort, a Childhood Arthritis and Rheumatology Research Alliance initiative.Methods.Time-of-diagnosis data for children with physician (MD) diagnosis of AAV and unclassified vasculitis (UCV) from 33 US/Canadian centers were analyzed. The European Medicines Agency (EMA) classification algorithm and European League Against Rheumatism/Paediatric Rheumatology International Trials Organisation/Paediatric Rheumatology European Society (EULAR/PRINTO/PRES) and American College of Rheumatology (ACR) criteria for GPA were applied to all patients. Sensitivity and specificity were calculated (MD-diagnosis as reference).Results.MD-diagnoses for 155 children were 100 GPA, 25 microscopic polyangiitis (MPA), 6 ANCA-positive pauciimmune glomerulonephritis, 3 Churg-Strauss syndrome, and 21 UCV. Of these, 114 had GPA as defined by EMA, 98 by EULAR/PRINTO/PRES, and 87 by ACR. Fourteen patients were identified as GPA by EULAR/PRINTO/PRES but not by ACR; 3 were identified as GPA by ACR but not EULAR/PRINTO/PRES. Using the EMA algorithm, 135 (87%) children were classifiable. The sensitivity of the EMA algorithm, the EULAR/PRINTO/PRES, and ACR criteria for classifying GPA was 90%, 77%, and 69%, respectively, with specificities of 56%, 62%, and 67%. The relatively poor sensitivity of the 2 criteria related to their inability to discriminate patients with MPA.Conclusion.EULAR/PRINTO/PRES was more sensitive than ACR criteria in classifying pediatric GPA. Neither classification system has criteria for MPA; therefore usefulness in discriminating patients in ARChiVe was limited. Even when using the most sensitive EMA algorithm, many children remained unclassified.

We investigate the long-term dynamics of spin textures prepared by cooling unmagnetized spinor gases of F = 1 87Rb to quantum degeneracy, observing domain coarsening and a strong dependence of the equilibration dynamics on the quadratic Zeeman shift q. For small values of |q|, the textures arrive at a configuration independent of the initial spin-state composition, characterized by large length-scale spin domains and the establishment of easy-axis (negative q) or easy-plane (positive q) magnetic anisotropy. For larger Iql, equilibration is delayed as the spin-state composition of the degenerate spinor gas remains close to its initial value. These observations support the mean-field equilibrium phase diagram predicted for a ferromagnetic spinor Bose-Einstein condensate and also illustrate that equilibration is achieved under a narrow range of experimental settings, making the F = 1 87Rb gas more suitable for studies of nonequilibrium quantum dynamics. [ABSTRACT FROM AUTHOR]

Abstract: In order to address the social, physical and economic determinants of urban health, researchers, public health practitioners, and community members have turned to more comprehensive and participatory approaches to research and interventions. One such approach, community-based participatory research (CBPR) in public health, has received considerable attention over the past decade, and numerous publications have described theoretical underpinnings, values, principles and practice. Issues related to the long-term sustainability of partnerships and activities have received limited attention. The purpose of this article is to examine the experiences and lessons learned from three Urban Research Centers (URCs) in Detroit, New York City, and Seattle, which were initially established in 1995 with core support from the Centers for Disease Control and Prevention (CDC). The experience of these Centers after core funding ceased in 2003 provides a case study to identify the challenges and facilitating factors for sustaining partnerships. We examine three broad dimensions of CBPR partnerships that we consider important for sustainability: (1) sustaining relationships and commitments among the partners involved; (2) sustaining the knowledge, capacity and values generated from the partnership; and (3) sustaining funding, staff, programs, policy changes and the partnership itself. We discuss the challenges faced by the URCs in sustaining these dimensions and the strategies used to overcome these challenges. Based on these experiences, we offer recommendations for: strategies that partnerships may find useful in sustaining their CBPR efforts; ways in which a Center mechanism can be useful for promoting sustainability; and considerations for funders of CBPR to increase sustainability.

Abstract: An experimental apparatus was developed to investigate the supercooling phenomenon of water inside cylindrical capsules used for a cold storage process. The coolant is a water–alcohol mixture controlled by a constant temperature bath (CTB). Temperatures varying with time are measured inside and outside the capsule. Cylinders with an internal diameter and thickness of 45 and 1.5 mm, respectively, were made from four different materials: acrylic, PVC, brass, and aluminum. The supercooling period of the water and the nucleation temperature were investigated for different coolant temperatures. The supercooling and nucleation probabilities are shown as a function of the coolant temperature for the four different materials.

The bulk radical polymerization of three methacrylic monomers, butyl, dodecyl, and 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate, were studied in the dark period after previous illumination by ultraviolet light at λ = 365 nm. An important postpolymerization process took place in all the polymerization reactions. This indicates that, even at low monomer conversions, a certain and nonnegligible radical concentration remains after switching off radical production. Monomer concentration measurements by FT-IR spectroscopy in the dark period showed that long-lived radicals continued the polymerization up to conversions that, in some cases, were higher than 70%. The half-lifetimes of these macroradicals ranged from 300 to 14000 s. Kinetic expressions were developed to determine the fraction of living and dead polymer during the course of the postpolymerization. The SEC traces of the resulting polymers showed bimodal molecular weight distributions and extremely high-molecular-weight polymers obtained in the post-effect period. By means of both kinetic results and molecular weight distribution, the values of the radical concentration in the dark period, the average termination rate coefficient of the macroradicals, and the transfer constant to the monomer were determined for the different polymerizations reactions carried out.

Dimethyl gold complexes bonded to partially dehydroxylated MgO powder calcined at 673 K were synthesized by adsorption of Au(CH3)2(acac) (acac is C5H7O2) from n-pentane solution. The synthesis and subsequent decomposition of the complexes by treatment in He or H2 were characterized with diffuse reflectance Fourier transform infrared (DRIFT), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopies. The XANES results identify Au(III) in the supported complexes, and the EXAFS and DRIFTS data indicate mononuclear dimethyl gold complexes as the predominant surface gold species, consistent with the lack of Au−Au contributions in the EXAFS spectrum and the presence of νas(CH3) and νs(CH3) bands in the IR spectrum. EXAFS data show that each complex is bonded to two oxygen atoms of the MgO surface at an Au−O distance of 2.16 Å. The DRIFT spectra show that reaction of Au(CH3)2(acac) with MgO at room temperature also formed Mg(acac)2 and H(acac) species on the support. Treatment of the dimethyl gold complexes in He or H2 at increasing temperatures varying from 373 to 573 K removed CH3 ligands and caused aggregation forming zerovalent gold nanoclusters of increasing size, ultimately with an average diameter of about 30 Å. Analysis of the gas-phase products during the genesis of the gold clusters indicated formation of CH4 (consistent with removal of CH3 groups) and CO2 at 473−573 K, associated with decomposition of the organic ligands derived from acac species. O2 and CO2 were also formed in the decomposition of ubiquitous carbonates present on the surface of the MgO support.

The effect of diffusion on linear, step-growth polymerizations has been quantified via “chain-by-chain” simulations of the polymerization process and a diffusion model consistent with reptation theories. The results show that diffusion limitations can narrow the molecular weight distribution and alter the way it evolves during polymerization; e.g., when diffusion is the limiting step, the polydispersity index (PDI1 = Mw/Mn) converges to a value of ~1.3 at complete conversion. Nevertheless, diffusion limitations have little effect on the time dependence of conversion. Consequently (for this type of polymerization), modeling of diffusion phenomena is important only when an accurate calculation of the MWD is needed. We also show that the numerical value of the Hatta number, at the point of entanglement (ϕ), can be used to determine whether diffusion limitations are likely to be important in a given system. Guidelines for the estimation of ϕ are given.

Cathodoluminescent (CL) powders of zinc aluminate activated with samarium ions have been prepared by a co-precipitation chemical process. Different doping concentrations in the start mixture and sintering temperatures for the precipitated powder were studied. It was observed that the crystalline characteristics of the powders depend upon the sintering temperature. For temperatures higher than 450 °C, the powders presented the cubic spinel phase with a lattice parameter value of 8.0756 Å, and grain sizes from 50 to 100 nm with semispherical shape. The CL emission spectra showed broad bands localized at 564, 602, 644, and 703 nm associated with 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2, and 4G5/2 → 6H11/2 transitions in the Sm3+ ions, respectively. Concentration quenching of the cathodoluminescence occurred at about 4.26 at% of the activator (Sm) concentration inside the sintered powders. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Studies were conducted to examine the effect of two vesicant chemical warfare agents (VCWA), one of them an arsenical, on cytokine gene expression in normal human epidermal keratinocyte (NHEK) cells. We tested 2,2′-dichlorethylsulfide (sulfur mustard, military designation HD) and 2,chlorovinyldichloroarsine (Lewisite, military designation L), which have significant differences in their chemical, physical, and toxicological properties. Human tumor necrosis factor-alpha (hTNF-α) cytokine was detected by using the enzyme-linked immunosorbent assay, a protein multiplex immunoassay, Luminex100™, and reverse transcription-polymerase chain reaction (RT-PCR). The messenger RNA expression of hTNF-α was determined to provide a semi-quantitative analysis. HD-stimulated NHEK induced secretion of hTNF-α in a dose-dependent manner. Dose response effect of Lewisite decreased hTNF-α levels. Time-response data indicated that the maximum response for HD occurred at 24 h with an associated cytotoxic concentration of 10–4mol/L. NHEK cells stimulated with 10–4mol/L HD for 24 h at 37°C increased detectable levels of hTNF-α from 5 to 28 ng/ml at an index of cell viability between 85 to 93% as detected by Luminex100™. Our results indicated that the increased levels of hTNF-α by HD are dependent on the primary cultures, cell densities, and chemical properties of the stimulation. Lewisite under the same conditions as HD caused a reduction of hTNF-α from control levels of 1.5 ng/ml to 0.3 ng/ml after stimulation (10–4mol/L), with an index of cell viability of ∽34%. We analyzed the transcriptional of hTNF-α gene and found that HD (10–6to 10–4mol/L) activates hTNF-α gene in cultured NHEK and that L at 10–6to 10–4mol/L markedly reduces hTNF-α gene. We conclude that the pro-inflammatory mediator, hTNF-α, could be a potential biomarker for differentiating between exposure of HD or L.

This review covers the general roles of members of the cysteine protease family of caspases in the process of apoptosis (programmed cell death) looking at their participation in both the “extrinsic” cell death receptor and the “intrinsic” mitochondrial cell death pathways. It defines the difference between initiator and effector caspases and shows the progression of caspase activations that ends up in the apoptotic cell death and elimination of a damaged cell. The review then presents what is currently know about the participation of caspases in the programmed cell death of inner ear sensory cells during the process of normal development and maturation of the inner ear and their importance in this process as illustrated by the results of caspase-3 gene knockout experiments. The participation of specific caspases and the sequence of their activation in the elimination (apoptosis) of damaged sensory cells from adult inner ears after an injury that generates oxidative stress are reviewed. Both the possibility and the potential efficacy of caspase inhibition with a broad-spectrum pancaspase inhibitor as an interventional therapy to treat and rescue oxidative stress-damaged inner ear sensory cells from apoptosis are presented and discussed.

A series of methacrylic copolymers was prepared by radical polymerization of the monomers 2-ethoxyethyl methacrylate and 2-hydroxyethyl methacrylamide and a small quantity of a cross-linking agent ethylene glycol dimethacrylate. Water swelling of the membranes, mechanodynamical analysis, density measurements, and ATR-FTIR studies were performed on the copolymers. High vacuum pressure techniques were used to evaluate the flow of He, O2, N2, CO2, CH4, CH3CH3, and CH2CH2 through these membranes, and solubility, diffusivity, and permeability coefficients were determined. The effect of the increase of the amount of methacrylamide in the copolymer on transport properties, glass transition, fractional free volume, cohesive energy density, and specific interactions has been studied and is reported in this work.

The reaction of Au(CH3)2(acac) with the partially dehydroxylated surface of γ-Al2O3 (calcined at 673 K) and the subsequent formation of supported gold clusters upon treatment of the supported species in He at various temperatures and 1 atm were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectorscopies, and X-ray absorption near edge structure (XANES). The IR spectra show that Au(CH3)2(acac) reacts readily at room temperature with both surface OH groups and coordinatively unsaturated aluminum sites of the γ-Al2O3 surface, forming supported mononuclear gold complexes and {Al}−acac species (where the braces refer to surface Al sites). EXAFS data demonstrate the formation of mononuclear gold complexes as the predominant surface gold species, confirmed by the lack of Au−Au contributions in the EXAFS spectra. The mononuclear complex is represented as {AlO}2−Au^III(CH3)2, with the Au−O bonding distance being 2.15 Å. Treatment of {AlO}2−Au^III(CH3)2 in He at 323 K and 1 atm led to formation of supported Au(III) oxide in the form of highly dispersed clusters. Further treatment of the samples led to the formation of metallic gold clusters of increasing size, ultimately those with an average diameter of about 30 Å. The {Al}−acac groups were converted to {Al}−acetate groups upon treatment in He at 423 K; further treatment at increasing temperatures removed all the organic ligands from the surface. The results provide the first evidence of the reaction of a metal acetylacetonate complex with an oxide surface that is characterized by essentially all the resultant surface species.

Gold clusters on the surface of MgO powder (calcined at 673 K) were prepared from adsorbed [Au(CH3)2(acac), where acac is C5H7O2] and characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES). One sample initially contained gold predominantly in the form of clusters approximated as Au6 on the basis of the EXAFS data showing first- and second-shell Au−Au coordination numbers of 4.0 ± 0.4 and 1.0 ± 0.1, respectively. The other sample initially contained larger clusters, with an average diameter of about 30 Å (containing about 100 atoms each, on average), as shown by the EXAFS first- and second-shell Au−Au coordination numbers of 9.4 ± 0.9 and 3.5 ± 0.4, respectively. The samples, in each of the three gases CO, O2, and He and in the presence of CO + O2 during CO oxidation catalysis, were investigated by EXAFS spectroscopy and XANES in a cell that was also a flow reactor. Data obtained during steady-state CO oxidation indicate the presence of gold clusters with an average diameter of about 30 Å, regardless of the initial size of the supported clusters. The XANES results demonstrate the simultaneous presence of both zerovalent and cationic gold in these catalysts.

An experimental study of the diffusion and permeability coefficients of helium, oxygen, and nitrogen in membranes prepared by solvent casting of commercial poly(vinyl chloride) (PVC) is reported. Transport parameters are very sensitive to the densification of PVC so that at 25 °C a sharp drop in the values of the permeability and solubility coefficients during the first week takes place. The variation of the transport parameters with aging time is nearly negligible after one month. Molecular dynamics methods were used to simulate a host matrix of poly(vinyl chloride) with density similar to that of the aged polymer. The application of the transition states approach to the simulation of the diffusion of gases in poly(vinyl chloride) gives values of the diffusion coefficient somewhat lower than the experimental ones for oxygen and nitrogen and higher for helium. Gas solution in poly(vinyl chloride) was simulated by means of a Monte Carlo cycle that inserts, with probability pin, or removes, with probability pre, particles of diffusant at randomly selected positions within the polymeric matrix. The values of the permeability coefficients calculated from the simulated diffusion and solubility coefficients are in very good agreement with the experimental results.

Two new monomers, cis-(2-phenyl-1,3-dioxan-5-yl) methacrylate (CPDM) and trans-(2-phenyl-1,3-dioxan-5-yl) methacrylate (TPDM), have been synthesized. The stereochemical configuration in both monomers was unequivocally assigned by correlation ¹H−¹³C NMR experiments. The radical polymerization reactions of both monomers were studied by ultraviolet spectroscopy and electron paramagnetic resonance spectroscopy to determine the polymerization rate parameter kp/kt^1/2 and the absolute propagation and termination rate constants (kp and kt) at different temperatures. The values of kp/kt^1/2 lie in the range 0.40−0.55 L^1/2/(mol^1/2 s^1/2) for CPDM and 0.29−0.37 L^1/2/(mol^1/2 s^1/2) for TPDM at temperatures between 45 and 70 °C, showing that the polymerization rate of the cis monomer with the substituents in equatorial−axial positions on the dioxane ring is higher than that of its trans counterpart with the phenyl and ester residue in equatorial positions on the dioxane ring. Using EPR measurements of the polymer radical concentrations, similar values for kp were obtained for both trans and cis monomers, whereas the termination rate constant of the trans monomer was about twice that of the cis monomer at the same temperature.

Chitosan is very efficient at removing vanadium from dilute solutions:  sorption capacity can reach 400−450 mg V g^-1 under optimum experimental conditions, which correspond to pH 3. In acidic solutions, the chitosan's amine groups are protonated, and vanadate anions can be exchanged with counterions bound to −NH3⁺ sites. A correlation is observed between the speciation diagram and the sorption isotherms, and it appears that decavanadate species are more favorable to sorption than other anionic vanadate species. Selecting experimental conditions under which decavanadate ions are the predominant form of vanadium results in enhanced sorption capacities and improved sorption kinetics. The results obtained in the study of vanadate desorption confirm the high affinity of chitosan for these polyoxoanions.

The temperature dependence of the α and β relaxations of poly(2-phenyl-5-acryloxymethyl-5-ethyl-1,3-dioxacyclohexane) is studied by broad-band dielectric spectroscopy. The strength of the α relaxation decreases with increasing temperature, pointing to an onset temperature (Δεα = 0) of ca. 97 °C. Seen from the high-temperature side, the α relaxation starts with zero intensity at the onset temperature and steeply increases with decreasing temperature until it levels off in the vicinity of Tg. Whereas in the glassy state the strength of the β relaxation is only slightly dependent on temperature, it undergoes a strong increase at temperatures above Tg. Arrhenius plots of both relaxations show that the β process remains operative at temperatures above the onset temperature of the α relaxation. The temperature dependence of the stretch exponent does not show a definite trend, most of the values obtained lying in the interval 0.3−0.5.

Site-isolated [Ir4(CO)12] on the surface of TiO2 powder (calcined at 200 or 400 °C) was prepared by deposition of [Ir4(CO)12] from n-hexane solution and, alternatively, by reductive carbonylation of TiO2-supported [Ir(CO)2(acac)] in the presence of CO at 1 atm and 100 °C. The preparation of the supported clusters and their subsequent decarbonylation by treatment in He or H2 were characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The first-shell Ir−Ir coordination number representing the supported iridium carbonyl clusters was found to be 3.0 ± 0.3, with an Ir−Ir bond distance of 2.68 ± 0.03 Å, consistent with X-ray diffraction data characterizing crystalline [Ir4(CO)12]. Decarbonylation in He at 300 °C gave TiO2-supported clusters retaining the tetrahedral Ir4 frame of the precursor [Ir4(CO)12], with an Ir−Ir first-shell coordination number of 3.0 ± 0.3. In contrast, decarbonylation of TiO2-supported [Ir4(CO)12] in H2 at 300 °C led to (nonuniform) aggregated iridium clusters with an Ir−Ir first-shell coordination number of 5.0 ± 1.0, a second-shell Ir−Ir coordination number of 2.0 ± 0.5, and a third-shell Ir−Ir coordination number of 7.0 ± 1.0. The chemistry on the TiO2 surface is consistent with the known solution and surface chemistry of iridium carbonyls. The site-isolated tetrairidium clusters on TiO2 are among the simplest and best-defined supported metals.

The diffusivity, permeability, and solubility coefficients of O2, N2, CO2, and CH4 have been measured in PVC and in four samples of PVC functionalized with mercapto pyridine groups up to 6.8, 11, 21, and 46 mol %. It has been found that the permeability of all four gases progressively increases by a factor of more than 4 because of a similar increase in the diffusion coefficients. In addition, permeability selectivity augments significantly for the gas pair O2/N2 and only slightly for the pair CO2/CH4. The structural changes in the modified samples have been monitored by means of density and Tg determinations and FFV calculations, which are a measure of interchain spacing and chain stiffness. An interpretation of the changes seen in the gas transport properties of modified PVC samples has been proposed in terms of the structural changes introduced by the progressive functionalization of the PVC chains.

Gold nanoclusters on MgO powder were prepared from adsorbed [Au(CH3)2(C5H7O2)] and characterized by infrared and X-ray absorption spectroscopies. Treatment of the samples in He or H2 at increasing temperatures removed CH3 and C5H7O2 ligands and caused the gold to aggregate into nanoclusters of increasing size, ultimately those with the properties of metallic gold. Treatment in He at 373 K gave clusters that are inferred to be nearly monodisperse Au6, with first- and second-shell Au−Au coordination numbers of 4.0 ± 0.4 and 1.0 ± 0.1, respectively, corresponding to Au6 octahedra.

The transport of argon in membranes of poly(bisphenol A carbonate-co-4,4‘-(3,3,5-trimethylcyclohexylidene)diphenol carbonate), under differences of pressure, Δp, lying in the interval 8−160 cmHg and in the temperature range 30−55 °C, is described. The experimental values of the permeability and diffusion coefficients at 30 °C and Δp = 76 cmHg are 4.5 barrers and 3.0 × 10^-8 cm² s^-1, respectively. The values of these parameters are nearly independent of the differences of pressure between the two faces of the membrane. The permeability and the diffusion coefficients obey Arrhenius behavior with activation energies of 3.7 and 6.7 kcal mol^-1, respectively. The permeation of argon in the membranes was simulated using the transition-state approach. Good agreement between simulated and experimental results is found by assuming that the polymer chains of the membrane fluctuate around equilibrium positions with a root-mean-square deviation Δ of 0.3 Å at 40 °C. Comparison of the experimental and simulated values for the diffusion and solubility coefficients suggests that the value of Δ increases with temperature at a rate of 0.005 Å K^-1.

Thermoelastic networks were prepared by end-linking hdroxyl-terminated poly(neopentylglycol hexafluoroglutarate) using tris(p-isocyanate phenyl) thiophosphate as cross-linking agent. The plot of birefringence versus stress exhibits negative deviations from linearity at elongation ratios larger than 1.9. The value of the optical configuration parameter Δa is 2.98 ų at 5 °C. Theoretical calculations carried out using the rotational isomeric state model give for this parameter the value of 2.24 ų, in fair agreement with the experimental results. The cause of the strong discrepancies between the theoretical and experimental results observed for the optical configuration parameter of polyesters containing phenyl groups in the acid residue is discussed.

Three experiments evaluated the effects of dietary Se and vitamin E on the ultrastructure of spermatozoa, ATP concentration of spermatozoa, and the effects of adding sodium selenite to semen extenders on subsequent sperm motility. The experiment was a 2 × 2 arrangement of treatments in a randomized complete block design. A total of 10 mature boars were fed from weaning to 18 mo of age diets fortified with two levels of supplemental Se (0 or .5 ppm) or vitamin E (0 or 220 IU/kg diet). The nonfortified diets contained .06 ppm Se and 4.4 IU vitamin E/kg. In Exp. 1, the spermatozoa from all boars were examined by electron microscopy. Vitamin E had no effect on structural abnormalities in the spermatozoa. When the low-Se diet was fed the acrosome or nuclei of the spermatozoa was unaffected, but the mitochondria in the tail midpiece were more oval with wider gaps between organelles. The plasma membrane connection to the tail midpiece was not tightly bound as when boars were fed Se. Immature spermatozoa with cytoplasmic droplets were more numerous when boars were fed the low-Se diet, but the occurrence of midpiece abnormalities occurred in boars fed diets with or without Se or vitamin E. Our results suggest that Se may enhance spermatozoa maturation in the epididymis and may reduce the number of sperm with cytoplasmic droplets. In Exp. 2, the concentration of ATP in the spermatozoa was evaluated in the semen of all treatment boars. When the low-Se diet was fed, ATP concentration was lower (P< .01), whereas vitamin E had no effect on ATP concentration. Experiment 3 investigated the effect of diluting boar semen with a semen extender with sodium selenite added at 0, .3, .6, or .9 ppm Se. Three ejaculates from each boar were used to evaluate these effects on sperm motility to 48 h after dilution. Sperm motility declined (P< .01) when Se was added to the extender, and this decline was exacerbated as the concentration of added Se increased (P< .01). The added Se was demonstrated to be tightly adhered to the spermatozoa. Overall, these results suggest that low Se-diets fed to boars resulted in abnormal spermatozoal mitochondria, a lower ATP concentration in the spermatozoa, and a loose apposition of the plasma membrane to the helical coil of the tail midpiece, but no effect from inadequate vitamin E was demonstrated. Adding sodium selenite to the semen extender reduced sperm cell motility.

An experiment involving a total of 61 crossbred boars evaluated the effects of dietary Se and vitamin E on spermatogenic development at various stages of sexual development and the prostaglandin F2α(PGF2α) content in the seminal vesicle and prostate glands at 18 mo of age. The experiment from 5.4 to 9 mo of age was conducted as a 2 × 2 factorial in a randomized complete block design. Dietary Se at 0 or .5 ppm was the first factor and vitamin E at 0 or 220 IU/kg diet was the second. From 9 to 18 mo of age, a group of sexually active and inactive boars was a third factor. Treatment diets were fed from weaning (28 d of age) to the end of the experiment. Three boars per treatment group at 5.4 (105 kg BW), 6.2 (130 kg BW), and 9.0 (150 kg BW) mo of age were killed and the testes collected. From 9 to 18 mo of age, three boars from each dietary treatment group were used for semen collection, and another set of three to four boars from each treatment group remained sexually inactive. At 18 mo, both sets of boars were killed and their testes, prostates, and seminal vesicles were collected. The testis at each age was evaluated for sperm reserve numbers and germ and Sertoli cell populations. At 5.4 or 6.2 mo of age, testicular sperm reserves were not affected by dietary Se (P> .15), at 9.0 mo of age there was a trend for a higher (P< .10) number of sperm reserves, and by 18 mo of age the Se-fed boars had higher (P< .01) numbers of sperm reserves. Vitamin E had no effect (P> .15) on testicular sperm reserves at any age period. Boars fed dietary Se had a greater number of Sertoli cells (P< .01) and round spermatids (P< .01) at 6.2 mo of age, but by 18 mo of age the boars fed Se had more Sertoli cells (P< .05), more secondary spermatocytes (P< .01), and more round spermatids (P< .05). Vitamin E did not affect Sertoli or germ cell populations at the various ages. Boars at 18 mo of age had lower PGF2αconcentrations in the prostate (P< .05) and seminal vesicles (P< .01) when vitamin E was fed, whereas Se had no effect. Sexually active boars had lower PGF2alpha concentrations in the seminal vesicles (P< .01) than sexually inactive boars, but there was no effect (P> .15) of sexual activity on the number of Sertoli cells, primary or secondary spermatocytes, or round spermatids. Our results indicate that Se has a role in establishing the number of boar spermatozoal reserves and Sertoli cells, whereas supplemental vitamin E did not affect these criteria.

We have fabricated and characterized Yba2Cu3O7−δ-Ba2HoSbO6a realized high Tcsuperconductor - ceramic insulator composite system in which particles of the superconductor and ceramic insulator could coexist with well defined separated phases left intact by stringent processing conditions. All the composites exhibit superconductivity at 92K. EDX analysis show that element% and atomic% of the composites are in a good agreement with those of their respective components. SEM studies show homogenous surface morphology and particle size distribution. There is no detectable interface interaction between component grains and Ba2HoSbO6grains are distinguishably distributed in the Yba2Cu3O7−δmatrix.