Unravelling the Molecular Structure and Confining Environment of an Organometallic Catalyst Heterogenized within Amorphous Porous Polymers

The catalytic activity of multifunctional, microporous materials is directly linked to the spatial arrangement of their structural building blocks. Despite great achievements in the design and incorporation of isolated catalytically active metal complexes within such materials, a detailed understanding of their atomic-level structure and the local environment of the active species remains a fundamental challenge, especially when these latter are hosted in non-crystalline organic polymers. Here, we show that by combining computational chemistry with pair distribution function analysis, 129 Xe NMR, and Dynamic Nuclear Polarization enhanced NMR spectroscopy, a very accurate description of the molecular structure and confining surroundings of a catalytically active Rh-based organometallic complex incorporated inside the cavity of amorphous bipyridine-based porous polymers is obtained. Small, but significant, differences in the structural properties of the polymers are highlighted depending on their backbone motifs.

Abiotic reduction of nitrite by Fe(II): a comparison of rates and N2O production

Abiotic reduction of nitrite (NO₂^-) by Fe(II) species (i.e., chemodenitrification) has been demonstrated in a variety of natural environments and laboratory studies, and is a potentially significant source of atmospheric nitrous oxide (N₂O) emissions. It is, however, unclear how chemodenitrification rates and N₂O yields vary among heterogeneous Fe(II) species under similar conditions and whether abiotic reduction competes with biological NO₂^- reduction. Here, we measured rates of NO₂^- reduction and extents of N₂O production by several Fe(II) species under consistent, environmentally relevant conditions (i.e., pH 7.0, bicarbonate buffer, and 0.1 mM NO₂^-). Nitrite reduction rates varied significantly among the heterogeneous Fe(II) species with half-lives (t_1/2) ranging from as low as an hour to over two weeks following the trend of goethite/Fe(II) ∼ hematite/Fe(II) ∼ magnetites > maghemite/Fe(II) > sediment/Fe(II). Interestingly, we observed no clear trend of increasing NO₂^- reduction rates with higher magnetite stoichiometry (x = Fe²⁺/Fe³⁺). Nitrogen recovery as N₂O also varied significantly among the Fe species ranging from 21% to 100% recovery. We further probed both chemodenitrification and biological denitrification in the absence and presence of added aqueous Fe(II) with a sediment collected from the floodplain of an agricultural watershed. While abiotic NO₂^- reduction by the sediment + Fe(II) was much slower than the laboratory Fe(II) species, we found near complete mass N balance during chemodenitrification, as well as evidence for both abiotic and biological NO₂^- reduction potentially occurring in the sediment under anoxic conditions. Our results suggest that in redox active sediments and soils both chemodenitrification and biological denitrification are likely to occur simultaneously, and that agricultural watersheds may be significant sources of N₂O emissions.

Reduction of PCE and TCE by magnetite revisited

Here we revisit whether the common mixed-valent Fe mineral, magnetite, is a viable reductant for the abiotic natural attenuation of perchloroethylene (PCE) and trichloroethylene (TCE) in anoxic groundwater plumes. We measured PCE and TCE reduction by stoichiometric magnetite as a function of pH and Fe(ii) concentration. In the absence of added Fe(ii), stoichiometric magnetite does not reduce PCE and TCE over a three month period under anoxic conditions. When Fe(ii) is added to magnetite suspensions, PCE and TCE are reduced under Fe(ii) and pH conditions that appear to be controlled by the solubility of ferrous hydroxide, Fe(OH)2(s). Reduction rates are slow with only 1 to 30% carbon products (primarily acetylene) accumulating over several months. We conducted a similar set of experiments with Fe(OH)2(s) alone and found that, compared to in the presence of magnetite, Fe(OH)2(s) reduces PCE and TCE only at Fe(ii) concentrations that are too high (≥13 mM, 726 mg L-1) to be representative of natural aquifer conditions. Our results suggest that magnetite present in aquifer sediments alone is unlikely to reduce PCE and TCE sufficiently fast to contribute to natural attenuation of PCE and TCE. The lack of compelling evidence for PCE and TCE reduction by magnetite raises important questions regarding the current application of using magnetic susceptibility as a potential indicator for abiotic natural attenuation. Dynamic conditions and high Fe(ii) concentrations that favor active precipitation of minerals, such as Fe(OH)2(s) in the presence of magnetite (or other Fe minerals), however, may lead to PCE and TCE reduction that could help attenuate PCE and TCE plumes.

International allied health education and cross-cultural perspectives

International partnerships develop long-lasting friendships among colleagues. This is a dividend that is of immense value in this otherwise terribly divided globe with health care issues being a major concern. The framework and lessons learned proposed herein should be of value to individuals in colleges and universities to promote a true learning experience for both partners that are enduring and replicable models of international cooperation.

Gonadotropin-releasing hormones in the brain and pituitary of the teleost, the white sucker

The present study investigated GnRH forms within the brain of a representative of the order Cypriniformes, the white sucker, Catostomus commersoni, using HPLC, RIA, and immunocytochemistry. Several immunoreactive (ir) GnRH forms were identified in the brain of the white sucker by chromatography and radioimmunoassay, including ir-salmon GnRH, ir-lamprey GnRH-I and -III, and ir-chicken GnRH-II. Results from immunocytochemical studies were consistent with multiple GnRH forms distributed in different patterns, particularly for fibers. Neuronal perikarya containing ir-salmon GnRH and ir-lamprey-like GnRH were found laterally within the preoptic area and rostral hypothalamus. Cells containing exclusively ir-salmon GnRH appeared slightly more rostrally, but in the same region. Fibers containing ir-salmon GnRH and ir-lamprey-like GnRH were seen throughout the caudal telencephalon and extended into the diencephalon, toward the pituitary. Fibers containing ir-chicken-II-like GnRH were also seen in the caudal telencephalon, but were concentrated more dorsally in the diencephalon. Within the pituitary, fibers containing ir-salmon GnRH and ir-lamprey-like GnRH entered the neurohypophysis, but differed in their destinations. Fibers containing ir-salmon GnRH remained within the neurohypophysis, while fibers containing ir-lamprey-like GnRH targeted adenohypophyseal tissue. These findings are consistent with the hypothesis that multiple GnRH forms with multiple functions exist within the brain and pituitary of teleosts and provide further evidence of a lamprey-like GnRH within an early evolved teleost species.

A model for design of health administration curriculum and instruction

Faculty members in health administration programs as in other professional programs tend to be trained in content appropriate to their field rather than as educators. Enhancement of the teaching skills of faculty will potentially improve the quality of the students' educational experience. Of particular note is the tendency of faculty to teach at the basic knowledge level and expect students to perform at the application and problem-solving levels. The purpose of this paper is to aid faculty in health administration improve their teaching activities and student evaluation. This goal will be accomplished through presentation of a model for systematic design of curriculum application of this model at the course and lesson levels.

Within herd comparison of teat dipping and dry cow therapy with only selective dry cow therapy in six herds

A within herd comparison of teat dipping and dry cow therapy (full treatment) with only selective dry cow therapy (partial treatment) was carried out in six commercial dairy herds for a two year period. In four herds, the incidence of clinical mastitis was 2 to 12 per cent higher in the partial treatment group. In another herd, in which the pattern of clinical mastitis isolates was unusual in that minor pathogens were isolated from 30 per cent of mastitis cases, the incidence was 43 per cent higher in the partial treatment group. In the remaining herd the incidence was 10 percent higher in the full treatment group. Streptococcus uberis mastitis was more common in the partial treatment groups of five herds; coliform mastitis was more common in the full treatment groups of two herds and similar in both groups in the other herds. High rates of coliform mastitis were associated with poor herd environmental conditions but this was not true for Strep uberis mastitis. Rates of staphylococcus aureus and Strep dysgalactiae mastitis were low in all herds. The level of major pathogen infection in cows completing the trial in all herds increased in the partial treatment group from 5 per cent of quarters at the start to 12 per cent at the finish of the trial. In the full treatment group, however, there was only a small increase in this level. In contrast, levels of Corynebacterium bovis infection increased by 17 per cent in both treatment groups. Continued use of teat dipping and dry cow therapy was associated with a higher rate of coliform mastitis in two of the three herds where there were poor standards of hygiene and husbandry.

Laboratory staff development practices: a statewide study

A statewide survey of staff development practices in New York State was completed to: 1) assess the current staff development practices for laboratory personnel in a variety of health care delivery settings; 2) determine the importance of selected laboratory practices to the professional growth of the laboratory staff; 3) make recommendations for staff development practices based on research findings. The study results are based on responses to a 1978 mail survey to laboratory staff employed in New York State. The most significant findings were that in over half of the laboratory settings surveyed three of six general types of laboratory staff development practices were nonexistent. Furthermore, regardless of size and/or type of laboratory setting, there were rare opportunities for staff development. The findings have implications for level of job satisfaction, level of professionalism, and even performance appraisal.

An automated admissions system for allied health schools

An automated system for admissions of allied health students was developed to facilitate the progress of admissions for applicants to the programs of study at the State University of New York at Buffalo. The data collection process has removed the tedious clerical functions of admissions from the faculty. Summary information is provided for each applicant in the form and at the time each program requests it. Data will be retained as a base for a student information system. Information retrieval and research capability is enhanced.

A volume sensor for a pneumatically driven LVAD

The volume sensor has proven to be a valuable tool in the operation and characterization of our pneumatically driven LVAD. It compensates for the decoupling between driver and LVAD that occurs in pneumatically actuated LVADs due to gas compressibility. Uses to which we have put the volume sensor represent only a small fraction of the potential applications. Additional uses contemplated include: Use as an alternate or backup for the R-wave detection network currently used to achieve synchronization with the natural heart. This could be done by starting the LVAD ejection phase when the filling flow rate drops below a given threshold, indicating that the left ventricle has finished filling the LVAD. Use for feedback for closed loop control of plate motion. Such control could reduce actuation delays without overdriving the LVAD. Use as a diagnostic tool to aid in the study of the LVAD and its interaction with the cardiovascular system. When used in conjunction with information on left ventricular, aortic, and drive pressures, it is possible to determine the resistance, inertia and compliant characteristics of the major elements of the LVAD and the vascular system to which it is joined.