Welding of precipitation-hardening stainless steels

Welding of precipitation hardening stainless steel

Photocatalytic Degradation of Selected Organophosphorus Pesticides Using Titanium Dioxide and UV Light

The photocatalytic degradation of five selected organophosphorus pesticides (OPPs), azinphos methyl, azinphos ethyl, disulfoton, dimethoate, and fenthion, has been investigated using TiO2 (photocatalyst) and UV irradiation. The addition of H2O2 (oxidant agent) into the illuminated aquatic suspensions was also surveyed. The degradation kinetics was studied under different experimental conditions such as pesticides’ and catalyst’s concentration. Experiments were performed in a Pyrex UV laboratory-constructed photoreactor equipped with 4 × 18 W low-pressure Hg lamps emitting at 365 nm (maximum intensity 14.5 mW cm−2 at distance 15 cm). The concentration of pesticides was determined by GC-NPD means. The extent of pesticide mineralization was assessed through TOC measurements. The results demonstrated that photolysis of target organophosphates in the absence of catalyst or oxidant is a slow process resulting in incomplete mineralization. Contradictory, studied pollutants were effectively degraded in the presence of TiO2; evolution of inorganic heteroatoms (SO42−, PO43−, NO2−, NO3−, and NH4+) as final products provided evidence that pesticide deterioration occurred. The photolysis efficiencies decreased in the order: disulfoton > azinphos ethyl > azinphos methyl > fenthion > dimethoate. Furthermore, a synergistic effect was observed with the addition of H2O2 in the pesticide-TiO2 suspensions. In all cases examined, reduction process appeared to follow pseudo first-order kinetics (Langmuir-Hinshelwood model). In conclusion, both catalytic systems investigated (UV-TiO2 and UV-TiO2-H2O2) have good potential for small-scale applications

Effects on the Photosynthetic Activity of Algae after Exposure to Various Organic and Inorganic Pollutants: Review

Algal studies remain necessary for risk assessment and their utility in ecotoxicology is the evaluation of lethal and sub-lethal toxic effects of potential toxicants on inhabitants of several ecosystems. Effects on algal photosynthetic apparatus caused by various chemical species have been extensively studied. The present chapter summarizes the published data concerning the toxicity of various organic and inorganic pollutants such as oils, pesticides, antifoulants and metals on photosynthesis of aquatic primary producers. Biochemical mode of action resulting in the disruption of photosynthesis depends on the chemical’s nature and the characteristics of the exposed microorganism. Observed differences in response and sensitivity by different species to the same toxicant were attributed to several algal characteristics including photosynthetic capacity, pigment type, cellular lipid and protein content, and cell size. Single species bioassays either for one chemical alone or in mixture have been well reported and tolerance of both marine and freshwater water-column phytoplaktonic species has been examined. Adequate published information on multispecies tests (communities) in laboratory and field studies exists. However, risk assessment on photosynthesis of microbenthic periphyton is inadequate, though it is essential especially for hydrophobic organic molecules. Further studies are required to evaluate the adverse effects of metabolites on aquatic microalgae

Bringing ethnomathematics to elementary school teachers in Papua New Guinea: a design-based research project

After 40 years of ethnomathematics research in Papua New Guinea and policies encouraging ethnomathematics in schools, it was time to look at professional learning for teachers so they could effectively implement the policies. Within a design-based research methodology, we designed a set of interlinked principles, tried them in several workshops for teachers, and revised the principles to take account of needs based on reflexivity and evaluations. We developed a manual to use in the workshops. We are continuing this research through several different phases, moving from direct delivery of the professional learning to teachers in various provinces and ecologies to delivery to trainers who then teach the teachers in three provinces, and finally by technology delivery. Early evaluation data suggest that the key principles showing the importance of culture, language and mathematical thinking in the teaching of early mathematics are sound. Workshops have been well received as teachers inquire into the mathematics of their own cultures. The need for a stronger understanding of early mathematics learning in general has been identified. The use of video of cultural practice and of young children learning to count and investigate has had a significant impact

Toxic Effects of the Organophosphorus Insecticide Fenthion on Growth and Chlorophyll Production Activity of Unicellular Marine Microalgae Tetraselmis suecica: Comparison between Observed and Predicted Endpoint Toxicity Data

This chapter provides the results of a laboratory ecotoxicological study conducted to assess the acute toxicity of the organophosphorus pesticide fenthion toward the marine microalgal species Tetraselmis suecica. Bioassays were performed, and algal densities and chlorophyll pigments fractions were measured in the exponential phase after 96 h of exposure to fenthion. Two quantitative structure activity relationships (QSARs) were used to estimate the toxicity of 13 primary metabolites and degradation products of fenthion toward the selected organism; the first was based on the use of the n-octanol/water partition coefficient, whereas the second was based on the solubility of the compound in water. Results revealed that fenthion can have marked effects on the growth and photosynthesis of the target primary producers of marine ecosystems T. suecica. The parent pesticide toxicant was found not toxic to the tested algal species up to 1.00 mg L−1, while higher treatment concentrations not only affected algal densities and significantly decreased specific growth rate values (μ) (p < 0.05) but also decreased the contents of photosynthetic pigments. The comparison between the observed and the predicted toxicity values of the parent compound fenthion indicated that the predictive capability of the QSARs applied can be considered highly satisfactory. Consequently, both QSAR models were used for the prediction of toxicity data of fenthion’s principal metabolites and degradation products

Is the United States Claims Court Constitutional?

This article will deal with two major constitutional problems that have resulted from the creation of the Claims Court. The first issue is the constitutionality of the appointment of existing Court of Claims Commissioners to be judges on the Claims Court during a four-year transition period. By legislatively designating the persons who are to serve as judges on the new court, Congress has usurped the presidential appointment power. The second issue relates to the constitutional status of the Claims Court. The Court of Claims which it replaces was created under article III of the Constitution, and the judges on it were therefore entitled to life tenure and salaries that could not be reduced during their terms in office. The new Claims Court, on the other hand, is designated by Congress as an article I court; the judges are to be appointed for only fifteen year terms, and their salaries are subject to control by Congress. The new court exercises full judicial authority, however, and has jurisdiction over cases of national importance in which the government of the United States has a great financial stake. Although the analysis of this issue is far from simple, this author concludes that Congress has exceeded its constitutional authority by failing to comply with the requirements of article III of the Constitution in establishing the Claims Court

Busy Streets Theory: The Effects of Communityâ engaged Greening on Violence

Lack of maintenance on vacant neighborhood lots is associated with higher levels of depression, anxiety, and stress for nearby residents. Overgrown grasses and dense brush provide hiding spots for criminals and space to conduct illicit activities. This study builds upon previous research by investigating greening programs that engage community members to conduct routine maintenance on vacant lots within their neighborhoods. The Clean & Green program is a communityâ based solution that facilitates residentâ driven routine maintenance of vacant lots in a midsized, Midwestern city. We use mixed effects regression to compare assault and violent crime counts on streets where vacant lot(s) are maintained by community members (N = 216) versus streets where vacant lots were left alone (N = 446) over a 5â year timeframe (2009â 2013). Street segments with vacant lots maintained through the Clean & Green program had nearly 40% fewer assaults and violent crimes than street segments with vacant, abandoned lots, which held across 4 years with a large sample and efforts to test counterfactual explanations. Communityâ engaged greening programs may not only provide a solution to vacant lot maintenance, but also work as a crime prevention or reduction strategy. Engaging the community to maintain vacant lots in their neighborhood reduces costs and may increase the sustainability of the program.HighlightsBlighted and abandoned properties generate substantial costs and risk for postindustrial cities.Communityâ engaged maintenance of properties can reduce blight and increase social cohesion.We compare levels of crime on streets with â greenedâ versus unmaintained vacant lots.Community greened lots may reduce blight and crime at lower cost to cities and build social capital.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146412/1/ajcp12270_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146412/2/ajcp12270.pd

Integrated supercritical fluid extraction and bioprocessing

ABSTRACT Supercritical fluids are increasingly being used and promoted at a laboratory and pilot scale to produce high value, natural bioactives from biologically based raw materials. Supercritical CO 2 is overwhelmingly the solvent of choice for these operations, but is largely limited to the processing of dry raw materials and the extraction of low polarity, low molecular weight compounds. The use of co-solvents and the use of alternative &apos;near-critical&apos; extraction fluids such as dimethyl ether show potential to mitigate these limitations. Commercialisation of new supercritical extraction processes has arguably been limited because the supercritical extraction process has been developed in isolation of other processing steps necessary to achieve a successful product. This study reviews recent developments in integrated processing that incorporate the use of supercritical fluids for bioseparations and in particular process schemes that produce high value natural bioactives. Integrated processes include prior operation (fermentation, extraction, enzyme pre-treatment, physical fractionation or size reduction) followed by supercritical extraction or fractionation and processes in which operations are carried out in situ in supercritical fluids (supercritical chromatography, enzymatic conversion, precipitation and coating of solutes). The use of co-solvents and alternative extraction solvents in these processes is discussed. Prospects for future developments are also discussed

Perpetrating Cyber Dating Abuse: A Brief Report on the Role of Aggression, Romantic Jealousy and Gender

There is increasing evidence that the use of elec-tronic communication technology (ECT) is being integrated into romantic relationships, which can be used as a medium to control a romantic partner. Most research focuses on the vic-tims of cyber dating abuse, however, we focused on the factors that predict perpetration of cyber dating abuse. We explored whether aggression (verbal aggression, physical aggression, anger and hostility), romantic jealousy (emotional, cognitive and behavioral jealousy), and gender predicted perpetration of cyber dating abuse (n = 189). We found that hostility, behav-ioral jealousy and gender significantly predicted perpetration of cyber dating abuse. The findings of this study contribute to our understanding of the psychological factors that drive cyber dating abuse in romantic relationships