Reductive dehalogenation of chlorinated aromatic and aliphatic hydrocarbons under anaerobic conditions

The process of reductive dehalogenation involves the removal of a halogen substituent from a molecule with the concurrent addition of electrons to the molecule, resulting in a more reduced and often less toxic product. Anaerobic bacteria have the potential to utilize hazardous chlorinated aromatic and aliphatic hydrocarbons as electron acceptors in metabolic reductive dehalogenation processes. In experiments performed with chlorinated aromatic compounds a highly enriched anaerobic culture stoichiometrically converted 2,4,6-trichlorophenol (2,4,6-TCP) to 4-monochlorophenol. Dehalogenation occurred only in alkaline media (pH 8-9) at concentrations of 2,4,6-TCP up to 1 mM. Data indicated that the dehalogenating organism did not fit into any of the typical metabolic classifications of anaerobic bacteria: methanogenic, sulfidogenic, nitrate-reducing, metal-reducing, or fermentative. Data suggested that dehalogenation was linked to growth and proceeded as a respiratory process. The organism was capable of utilizing a number of supplementary chlorinated compounds as electron acceptors, in addition to the 2,4,6-trichlorophenol. Experiments performed with chlorinated aliphatic compounds involved soil microcosms from a perchloroethylene (PCE) contaminated site. The approach was to provide slowly fermentable compounds, which are not widely used by bacteria, as a source of low potential electrons. The data obtained show that N-Z-Soy Peptone, xanthan gum, polyethylene glycol-60, Tween-80, xanthine, crude DNA, and a volatile fatty acid mix were all able to support dehalogenation as far as cis-dichloroethylene. Additionally, the data show that xanthan gum was able to carry the dehalogenation process past dichloroethylene to vinyl chloride, with no perchloroethylene or trichloroethylene remaining. The active population was able to dehalogenate up to 250 μM PCE (about 40 ppm). Inhibitor experiments performed with molybdate and bromo-ethane sulfonic acid suggested that part of the active population consisted of sulfidogenic bacteria, while methanogens did not play a significant role in the dehalogenation activity. Taken together the results of these studies investigating the reductive dehalogenation of chlorinated aromatic and aliphatic compounds under anaerobic conditions demonstrate that bacteria which play significant roles in the dehalogenation processes come from diverse metabolic backgrounds which include fermentative, sulfidogenic, and actual chlorinated-compound-respiring organisms

Leading Through Crisis: The COVID-19 Pandemic’s Impact on the School Principalship, A Delphi Study

This dissertation study examined the impacts of the COVID-19 Pandemic on the K-12 School Principalship and attempted to forecast the future of the principalship post-Pandemic. Using a forecasting method known as the Delphi Technique, I solicited public K-12 principals working in the Commonwealth of Virginia with at least 3 years of administrative experience to serve as participants. In total, 26 practicing principals completed three questionnaires offering their expert opinions on pre-Pandemic roles and responsibilities of the school principal and how those roles were impacted throughout the Pandemic. Additionally, the participants made predictions about the future of the school principalship. Findings revealed the top three pre-Pandemic roles and responsibilities were building relationships, instructional leadership, and promoting school safety. Participants also explained that their job throughout the Pandemic evolved from supervising virtual instruction, to monitoring COVID-19 mitigation strategies, to managing teacher absenteeism and increased student disciplinary infractions. Participants forecasted that each of the following will be long term challenges (lasting more than five years) for school principals: decreased student achievement, low morale among teachers, student social emotional challenges, and teacher shortages

Cardiovascular and hepatic toxicity of cocaine: potential beneficial effects of modulators of oxidative stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy

Economic Evaluation of Teacher Induction Programs: A Toolkit How-to Guide

Research shows that teacher induction programs can be effective as measured by a number of outcomes. However, research also shows that teacher induction programs vary greatly from one district to another. Furthermore, there is no research that examines teacher induction programs with respect to costs and benefits. Educational leaders and stakeholders do not need to wait on formal institutional research to do such an economic evaluation. This how-to guide, in combination with a comprehensive report, the Teacher Induction Program Cost Matrix and the Teacher Induction Program Benefit-Cost Workbook, comprises a toolkit designed to allow school and district leaders to conduct an economic evaluation of their teacher induction program

Economic Evaluation of Teacher Induction Programs: A Report

Research shows that teacher induction programs can be effective as measured by a number of outcomes. However, research also shows that teacher induction programs vary greatly from one district to another. Furthermore, there is no research that examines teacher induction programs with respect to costs and benefits. Educational leaders and stakeholders do not need to wait on formal institutional research to do such an economic evaluation. This report, in combination with a How-to-Guide, the Teacher Induction Program Cost Matrix and the Teacher Induction Program Benefit-Cost Workbook, comprises a toolkit designed to allow school and district leaders to conduct an economic evaluation of their teacher induction program

Variabilidad genética y caracterización espermática de las poblaciones en cautiverio del Tapir Centroamericano (Tapirus bairdii) en Panamá.

El Tapir (mamífero de mayor tamaño de Centroamérica) se encuentra en peligro de extinción. Una de las dificultades que se presentan para su conservación es el alto costo económico que representa el planeamiento e implementación de planes de preservación de un número mínimo de animales para mantener la variabilidad genética que garantice la supervivencia de la especie. Además, se requiere mucho esfuerzo para su reproducción en cautiverio y es difícil mantener poblaciones de este tipo que se "auto-sustenten" genéticamente. Esto es debido al limitado espacio disponible que no permite mantener poblaciones suficientemente grandes para evitar los impactos negativos de la endogamia ni la disminución de la variabilidad debido a la deriva genética. Los desarrollos biotecnológicos en el campo de la reproducción, ofrecen alternativas muy interesantes y únicas para el mejoramiento genético y el rescate de diferentes especies animales. Entre los objetivos de este estudio están: 1) caracterizar el nivel de variabilidad genética y endogamia presentes en las poblaciones de tapires en cautiverio de Panamá y 2) caracterizar la biología reproductiva del macho del tapir. Para tal fin, se recolectaron muestras de semen por electroeyaculación, sangre y pelo de todos los individuos. Se realizaron estudios moleculares, a partir de DNA extraído de las muestras de sangre, utilizando la técnica de microsatélites (mediante la técnica de PCR con cola M13) para determinar la variabilidad genética de los individuos y el nivel de endogamia presente en las poblaciones estudiadas. Los estudios relacionados a la caracterización espermática de la especie consistieron en la determinación de características generales del eyaculado más las características morfológicas del esperma, llevados a cabo por primera vez a nivel mundial gracias a este proyecto. Los resultados indican que el nivel de variabilidad genética presente en estas pobiaciones refleja la variabilidad presente en las poblaciones silvestres y, hasta el momento, no se ha visto afectado por la endogamia. Con respecto a las características espermáticas, las poblaciones presentan teratospermía, sin embargo, esto parece no estar relacionado a los niveles de variabilidad genética, sino a factores de manejo como la dieta, y no ha afectado la capacidad reproductiva de los individuos por el momento. Este estudio es un medio para desarrollar técnicas y planes de manejo que se conviertan en una garantía para la conservación de la biodiversidad genética de esta especie en peligro de extinción

How can Small- and Medium-sized Enterprises (SMEs) Successfully Evolve? Lessons learned from Apparel and Textile SMEs in Biella, Italy

Despite SMEs significant contribution to a nation\u27s economy in terms of the number of firm establishment and employment, only 50% of SMEs in the U.S. survive five years. Compared to SMEs in other countries, many Italian firms started as small family businesses in a district and have evolved into a global firm such as Ermenegildo Zegna. To understand how SMEs can evolve successfully, it is critical to learn from successful Italian apparel/textile firms that started as SMEs. Built on the life cycle model of new SMEs, the purpose of this study is to explore the evolution patterns of successful apparel and textile firms in Biella, Italy and analyze the characteristics of successful firms. Analyses of thirteen interviewed firms revealed that branding (3rd stage) and internationalization activities (4th stage) emerged very early. The findings collectively suggest that to successfully evolve, SMEs need to focus on branding, globalization, innovation and sustainable initiatives

Switching on microglia with electro-conductive multi walled carbon nanotubes

We explored the mechanisms underlying microglia cell-carbon nanotube interactions in order to investigate whether electrical properties of Carbon-Nanotubes (CNTs) could affect microglia brain cells function and phenotype. We analyzed the effects induced by highly electro-conductive Multi-Walled-Carbon-Nanotubes (a-MWCNTs), on microglia cells from rat brain cortex and compared the results with those obtained with as prepared not conductive MWCNTs (MWCNTs) and redox-active Double-Walled-Carbon-Nanotubes (DWCNTs). Cell viability and CNT capacity to stimulate the release of nitric oxide (NO), pro-inflammatory (IL-1b, TNF-a) and anti-inflammatory (IL-10, TGF-b1) cytokines and neurotrophic factors (mNGF) were assessed. Electro-conductive MWCNTs, besides not being cytotoxic, were shown to stimulate, at 24 h cell exposure, classical "M100 microglia activation phenotype, increasing significantly the release of the main pro-inflammatory cytokines. Conversely, after 48 h cell exposure, they induced the transition from classical "M100 to alternative "M200 microglia phenotype, supported by anti-inflammatory cytokines and neuroprotective factor mNGF release. The analysis of cell morphology change, by tubulin and CD-206 þ labelling showed that M2 phenotype was much more expressed at 48 h in cells exposed to a-MWCNTs than in untreated cells. Our data suggest that the intrinsic electrical properties of CNTs could be exploited to modulate microglia phenotype and function stimulating microglia anti-inflammatory potential

STRUCTURAL AND FUNCTIONAL CHARACTERIZATION OF THE PANAMANIAN GOLDEN FROG (ATELOPUS ZETEKI) SPERMATOZOA – IMPACT OF MEDIUM OSMOLALITY AND CRYOPRESERVATION ON MOTILITY AND CELL VIABILITY

The Panamanian Golden Frog (Atelopus zeteki, Anura: Bufonidae), an endemic species from Panama, is critically endangered and believed to be extinct from the wild. Infectious disease, habitat destruction and pet trade are among the major causes of the populations decline. Conservation initiatives in Panama and the US have established captive breeding programs for the species but there is still much to be learned about its reproductive physiology to manage and sustain populations using Assisted Reproductive Technologies (ARTs). The main objectives of this dissertation were: 1) characterize the general sperm parameters and assess the effect of hormonal stimulation on motility, forward progressive motility, DNA integrity, sperm morphology and seasonality; 2) identify the effect of extracellular conditions, mainly dilution and temperature, on motility, forward progressive motility, duration of motility, morphology and DNA integrity; and 3) evaluate the effect of cryoprotectants on motility, forward progressive motility and sperm DNA integrity before and after freezing. Results demonstrated that: 1) A. zeteki sperm morphology is similar to that described in other Bufonids; the species successfully produces high quality spermatozoa when stimulated with intraperitoneal injection of Amphiplex, GnRH and hCG; hormonal stimulation is not detrimental to the motility parameters, cell morphology or DNA integrity; and, there is no seasonal effect on the response to the hormonal stimulation. These results indicate that the use of hormone treatments can be included in captive breeding programs to safely collect good quality sperm; 2) dilution of spermic urine in water highly reduces sperm motility, forward progressive motility, DNA and morphological integrity while storage of spermic urine at 4 °C preserves sperm quality for at least 46 min after collection; and 3) some recovery of viable A. zeteki spermatozoa after cryopreservation can be achieved by equilibrating the ARS-diluted samples for 5 min at 4 °C in CPA3-REY, using step-wise cooling before plunging the samples in LN2. Collective results offer missing information on the reproductive biology of the male A. zeteki and lead to the application of ARTs for the captive management of this charismatic but critically endangered species