The electrochemistry of lead dioxide formed on lead and lead alloys in sulphuric acid

The electrochemistry of lead dioxide has been studied using the techniques of linear sweep voltammetry, potentiostatic pulse experiments and a.c. impedance measurements. A morphological examination was also carried out using the technique of scanning electron microscopy. The formation of lead dioxide was investigated on both the flat lead/lead alloy electrode and the porous electrode which was produced by oxidation of a standard automotive positive paste on a lead/lead alloy base. The electrochemistry of the pure lead electrode (both flat and porous) was investigated and the effect on this of various alloy additions was observed. The alloys used, all of potential industrial importance, were lead-antimony, lead-bismuth, lead-calcium-tin and lead-calcium-tin-bismuth at various levels of bismuth addition. An a. c. study of Pb-Ca-Sn-Mg-Al is also included. The effect of antimony addition to lead has been isolated as the production of a secondary oxidation layer. This provides an explanation for the superior active material retention of antimony containing grids in the lead-acid battery, the relatively large material development with the antimonial alloy giving rise to a more mechanically sound function between grid and paste. The formation of this extra corrosion layer on antimonial lead may also explain the high degree of top bar corrosion which occurs in the oxygen region of the battery. The commercial significance of bismuth as a grid alloying ingredient has been highlighted and'a useful bismuth concentration range determined for both lead and lead-calcium-tin alloys

The Impact of Pedestrian Crossing Flags on Driver Yielding Behavior in Las Vegas, NV

Walking is the most affordable, accessible, and environmentally friendly method of transportation. However, the risk of pedestrian injury or death from motor vehicle crashes is significant, particularly in sprawling metropolitan areas. The purpose of this study was to examine the effect of pedestrian crossing flags (PCFs) on driver yielding behaviors. Participants crossed a marked, midblock crosswalk on a multilane road in Las Vegas, Nevada, with and without PCFs, to determine if there were differences in driver yielding behaviors (n = 160 crossings). Trained observers recorded (1) the number of vehicles that passed in the nearest lane without yielding while the pedestrian waited at the curb and (2) the number of vehicles that passed through the crosswalk while the pedestrian was in the same half of the roadway. ANOVA revealed that drivers were significantly less likely to pass through the crosswalk with the pedestrian in the roadway when they were carrying a PCF (M = 0.20; M = 0.06); drivers were more likely to yield to the pedestrian waiting to enter the roadway when they were carrying a PCF (M = 1.38; M = 0.95). Pedestrian crossing flags are a low-tech, low-cost intervention that may improve pedestrian safety at marked mid-block crosswalks. Future research should examine driver fade-out effects and more advanced pedestrian safety alternatives

Quantum Chemical Lipophilicities of Antimalarial Drugs in Relation to Terminal Half-Life

According to the WHO, artemisinin-based combination therapies (ACTs) have been integral to the recent reduction in deaths due to Plasmodium falciparum malaria. ACT-resistant strains are an emerging problem and have evolved altered developmental stages, reducing exposure of the most susceptible stages to artemisinin drugs in popular ACTs. Lipophilicity, log Kow, is a guide in understanding and predicting pharmacokinetic properties such as terminal half-life which alters drug exposure. Consistent log Kow values are not necessarily available for artemisinin derivatives designed to extend terminal half-life, increase bioavailability, and reduce neurotoxicity. For other drugs used in ACTs, an assortment of experimental and computational log Kow values are available in the literature and in some cases, do not account for subtle but important differences between closely related structures such as between diastereomers. Quantum chemical methods such as density functional theory (DFT) used with an implicit solvent model allow for consistent comparison of physical properties including log Kow and distinguish between closely related structures. To this end, DFT, B3LYP/6-31G(d), with an implicit solvent model (SMD) was used to compute ΔGowo and ΔGvowo for 1-octanol–water and olive oil–water partitions, respectively, for 21 antimalarial drugs: 12 artemisinin-based, 4 4-aminoquinolines and structurally similar pyronaridine, and 4 amino alcohols. The computed ΔGowo was close to ΔGowo calculated from experimental log Kow values from the literature where available, with a mean signed error of 2.3 kJ/mol and mean unsigned error of 3.7 kJ/mol. The results allow assignment of log Kow for α-and β-diastereomers of arteether, and prediction of log Kow for β-DHA and five experimental drugs. Linear least square analysis of log Kow and log Kvow versus terminal elimination half-life showed strong linear relationships, once the data points for the 4-aminoquinoline drugs, mefloquine and pyronaridine were found to follow their own linear relationship, which is consistent with their different plasma protein binding. The linear relationship between the computed log Kvow and terminal elimination half-life was particularly strong, R2 = 0.99 and F = 467, and can be interpreted in terms of a simple pharmacokinetic model. Terminal elimination half-life for β-DHA and four experimental artemisinin drugs were estimated based on this linear relationship between log Kvow and terminal t1/2. The computed log Kow and log Kvow values for epimers α- and β-DHA and α and β-arteether provide physical data that may be helpful in understanding their different pharmacokinetics and activity based on their different molecular geometries. Relative solubility of quinine and quinidine are found to be sensitive to thermal corrections to enthalpy and to vibrational entropy and do not follow the general trend of longer terminal t1/2 with greater predicted log Kow. Geometric relaxation of α- and β-DHA in solvent and inclusion of thermal correction for enthalpy and entropy results in correct prediction that α-DHA is favored in aqueous environments compared to β-DHA. Predictions made regarding experimental drugs have implications regarding their potential use in response to artemisinin drug-resistant strains

DVT Presentations to an Emergency Department: A Study of Guideline Based Care and Decision Making.

Pre-test probability scoring and blood tests for deep venous thrombosis (DVT) assessment are sensitive, but not specific leading to increased demands on radiology services. Three hundred and eighty-five patients presenting to an Emergency Department (ED), with suspected DVT, were studied to explore our actual work-up of patients with possible DVT relating to risk stratification, further investigation and follow up. Of the 205 patients with an initially negative scan, 36 (17.6%) were brought for review to the ED Consultant clinic. Thirty-four (16.6%) patients underwent repeat compression ultrasound with 5 (2.4%) demonstrating a DVT on the second scan. Repeat compression ultrasound scans were performed on 34 (16.6%) patients with an initially negative scan, with essentially the same diagnostic yield as other larger studies where 100% of such patients had repeat scanning. Where there is ongoing concern, repeat above-knee compression ultrasound within one week will pick up a small number of deep venous thromboses

O PROESDE E A EXTENSÃO UNIVERSITÁRIA EM SANTA CATARINA

A pesquisa que se apresenta é um projeto de tese de doutorado, que tem como objetivo geral a análise da extensão universitária como contribuição para o desenvolvimento regional, tendo como pano de fundo o Programa de Educação Superior para o Desenvolvimento Regional, PROESDE, em Santa Catarina. Trata-se de uma pesquisa em andamento, portanto, com estudos não finalizados. Pretendese, por meio do método indutivo, estudar as políticas públicas para o Ensino Superior no Brasil e em Santa Catarina, pesquisar o Programa PROESDE nas Universidades do Sistema ACAFE, atores e interventores para a sua criação e desenvolvimento, descrever o contexto histórico e conceitual da extensão universitária no Brasil, além de realizar pesquisa qualitativa, por intermédio de entrevistas com roteiro semiestruturado em diálogo com a ótica sociológica de Pierre Bourdieu, com os agentes das diferentes Universidades do Sistema ACAFE, a fim de investigar o quanto o referido Programa impactou suas vidas. O PROESDE é um programa de educação superior para o desenvolvimento regional, (dentre os demais programas de oferecimento de bolsa que fazem parte do Programa UNIEDU, fundamentado pelos artigos 170 e 171 da Constituição Estadual), criado pelo Estado de Santa Catarina (regulamentado pela Portaria Normativa 2180/SED/2020), que tem como objetivo: “a concessão de bolsas de estudo para estudantes matriculados em Cursos de Graduação em áreas estratégicas e de Licenciatura, sob a coordenação da Diretoria de Políticas e Planejamento Educacional - DIPE, da Secretaria de Estado da Educação - SED.” (SANTA CATARINA, UNIEDU, 2021). Beneficia estudantes matriculados em cursos nas Instituições de Ensino Superior mantidas por Fundações Educacionais instituídas por Lei Municipal. Deve promover o ensino, a pesquisa e a extensão, em articulação com a formação acadêmica e o desenvolvimento educacional e socioeconômico da região, por meio de Projetos de Extensão. (SANTA CATARINA, UNIEDU, 2021). O benefício econômico ao estudante resulta na gratuidade da mensalidade do curso de graduação, no limite de até 02 (dois) salários mínimos, durante o período de 01 ano. No País, 88% das Instituições de Ensino Superior são particulares. Em 2018, o mercado das IES particulares concentrou 75% das matrículas. (BRASIL, ABMES, 2019). Em Santa Catarina, o PROESDE é de fundamental importância para muitos jovens, o que faz com que pesquisas relacionadas ao tema devam ser incentivadas, pois, reconhece-se a estreita relação entre o desenvolvimento socioeconômico de uma região e o grau de escolaridade da população, além do crescimento pessoal e prático-profissional que traz a participação em um projeto de extensão, tudo isso, atrelado ao fato de que a maioria das pessoas depende de auxílio econômico para cursar o ensino superior, diante da escassez de universidades públicas para a demanda que se apresenta

In Defense of Sarah Lawrence College

The following letters were written in response to a recent attack in the media on Sarah Lawrence. They were sent, as a group, to the Coordinating Council of the National Women\u27s Studies Association. The staff of the Women\u27s Studies Newsletter has decided to give them national circulation

Preventive Benefits of U.S. Childcare Subsidies in Supervisory Child Neglect

Using data from age 3 of the Fragile Families and Child Wellbeing Study, the current study explores the complex relationships between U.S. child care subsidies and neglect. Specifically, the study examines two research questions: (1) Are U.S. child care subsidies associated with selfreported neglect among low-income mothers? (2) What individual types of self-reported neglect are significantly reduced by receipt of child care subsidy? Using negative binomial regression examining the relationships among mothers who were income-eligible for child care subsidy, we found that child care subsidy was associated with lower levels of supervisory neglect, indicating an important role of subsidy in the lives of low-income families