Effects of Cr(III) organic compounds on Lactobacillus plantarum

Biotransformation of Cr(VI) to less toxic Cr(III) has been known to produce insoluble Cr(III) compounds and soluble Cr(III) organic complexes. However, recent research reports have indicated that Cr(III) organic complexes are relatively stable in the environment. Little has been reported on the fate and toxic effects of Cr(III) organic compounds on organisms. In this study, the toxic effects of the soluble Cr(III) organic complexes [Cr(III) citrate, Cr(III) histidine, Cr(III) lactate and Cr(III) glutamate] to a local strain of Lactobacillus plantarum isolated from sauerkraut was investigated. Growth inhibition, viable cell count and lactic acid inhibition were measured to determine the toxicity potential of the test compounds. The EC₅₀ values of Cr(III) citrate, Cr(III) histidine, Cr(III) lactate, and Cr(III) glutamate, calculated from the percent growth inhibition were found to be 56 mg L^?1, 70 mg L^?1, 81 mg L^?1, and 85 mg L^?1, respectively. Similar trend was observed in the viable cell counts and lactic acid production. Cr(VI) was observed to be more toxic than the Cr(III) organic compounds, while inorganic Cr(III) was the least toxic. The severity seemed to increase with increase in chromium compounds’ concentration. The results showed that Cr(III) citrate was the most toxic Cr(III) organic compound, while Cr(III) glutamate was the least.     

Sustainable development in East Africa: impact evaluation of regional agricultural development projects in Burundi,Kenya, Rwanda,Tanzania, and Uganda

Investments in agricultural technologies, capacity building and policy harmonization are needed to support sustainable development across Africa. Regional development projects can facilitate the adoption of agricultural technologies and innovations across nation-state borders and generate benefits for shared prosperity. This paper uses panel data from 1,160 smallholder households including beneficiaries and non-beneficiaries from five countries in East Africa - Burundi, Kenya, Rwanda, Tanzania, and Uganda. From a pool of over 90 projects implemented over a span of 15 years, 23 regional projects are included in this study. The major economic benefits to smallholder participants are higher crop productivity and income, access to adaptable technologies, access to markets, higher livestock and milk production, gender equality, enhanced food security, resilience and capacity building for uptake and scaling up of future innovation platforms. For example, the adoption of low-cost tissue culture banana by the beneficiaries increased their incomes by 15% in Rwanda while the adoption of appropriate land and water management technologies increased the potato yields from 2.8 tons (USD 2,840/ha) to over 7.5 tons (USD 7,410/ha) in Kenya. The beneficiaries ensured value added to commodities like bananas (for export) and orange-fleshed sweet potatoes (a nutrition-sensitive intervention for enhancing domestic intake of vitamin A) in Burundi, Kenya, Rwanda and Uganda. Additionally, milk production increased from 6 to 11 L per cow per day in Uganda and from 6 to 8 L per cow per day in Tanzania, with increases in sales generating USD 115 per cow per month above the non-beneficiaries. These results are supported by previous studies on technology adoption, investments in agriculture and well-being outcomes. Our findings with the higher farm income Difference-in-Differences (DiD) estimator for the female beneficiaries compared to male beneficiaries might have important implications for investing in regional development projects that will close the gender gap in agricultural productivity in Africa. Regional projects can also support post-conflict development efforts for food security and peace in fragile contexts such as in Burundi. Our findings might serve as an input to the African Union's Comprehensive Africa Agriculture Development Programme, localization of the United Nations Sustainable Development Goals related to food security and agriculture in Africa and an input to monitoring, evaluation and learning.     

Fluoride removal studies using virgin and Ti (IV)-modified Musa paradisiaca (plantain pseudo-stem) carbons

The preparation of carbons in virgin and Ti-modified forms under controlled conditions at low temperature from plantain pseudo-stem (Musa paradisiaca) was achieved. These prepared carbons were characterized for instrumental studies such as BET, FTIR, XRD, SEM with EDS and TGA to understand the chemistry and modification. The determination of IEP and pH_ZPC established the presence of positive surface sites on the virgin (VMPC) and Ti-modified (TiMPC) carbons to facilitate the sorption of fluoride. The fluoride removal efficiency as a function of time, pH, dose, initial fluoride concentration, temperature, and co-ion intervention was studied. The maximum fluoride removal of about 81.2 and 97.7% was achievable with VMPC and TiMPC, respectively, after 20 min at the pH of 2.04 and continued for the equilibrium of 60 min. Temperature was found to be influential both by way of initial increase followed by a decrease in the fluoride uptake of MPCs. Regeneration was very consistent up to 7 cycles with the residual fluoride concentration below the WHO guide line of 1.5 mg L^?1. Highest intervention due to hydrogen carbonate ions was observed during the fluoride removal process. Kinetic (pseudo-first-order, pseudo-second-order, and intra-particle diffusion) and isotherm models (Langmuir, Freundlich, and DKR) were checked for their compliance with the present sorption system. These low temperature synthesized MPCs are found to be effective candidates in the process of fluoride abatement in water.

     

Moving towards urban sustainability in Kenya: a framework for integration of environmental,economic, social and governance dimensions

Global urban development is increasingly becoming an aspect of focus as nations fight sustainability challenges. A review of the current literature on urban sustainability suggests that research on development of cities, in both developed and developing countries, is growing fast, with an emphasis on sustainable development. However, very little of this research contains an integrated framework to systematically identify and examine the various dimensions of urban sustainability and to measure and evaluate them appropriately. Cities are more than the sum of their sectors, and are complex and interdependent systems on whose dynamics the quality of life of millions of human beings and a good part of the economy depend. Environmental, economic, social and governance problems can create formidable barriers to urban sustainability. Governance remains a critically important dimension of urban sustainability, especially when discussing urbanization in developing countries, given rapid population movements and imbalances in socio-economic development. Understanding how cities function is fundamental to resolving these imbalances. The aim of this paper is to provide a review and analysis of the concept of urban sustainability and to propose the development of a holistic framework through integration of environmental, economic, social, and governance dimensions of sustainability. Such a review would make it possible to understand the complex dynamics of the four dimensions and to assess the progress and challenges in moving towards urban sustainability, taking the case of Nairobi, Kenya, as an example. The paper argues that, for urban sustainability in developing countries, more emphasis should be placed on the governance dimension, because this is where the biggest challenge exists, with increasing needs for immediate management of rapid urbanization.     

斯里兰卡CKDu病区地下水源饮用水关键问题及解决策略

不明原因肾病(CKDu)是斯里兰卡亟需解决的重要民生问题,其地下水源饮用水中的溶解性污染物可能是重要的致病原因。系统分析了北部中心省内高、低、非发病区及对照区 (HR、LR、NR、CR)干湿季地下水的水化学特征和DOM特性,结果表明：地下水主要呈Ca-Mg-HCO₃型,硬度和F⁻超标率较高,是地下水作为饮水安全保障最关键的指标;地下水中DOM主要为自生源,芳香性和腐熟化程度较低,主要为富里酸、腐殖酸和小分子蛋白质类物质;湿季DOM浓度较高,是Fe浓度增加的关键原因;而干季地下水中微生物活性较高,腐殖质和蛋白质发生分解,小分子络氨酸/赖氨酸的浓度增加。同时,发现不同区域地下水中DOM的生物利用性表现为HR−1,芳香性较高。有机无机的相互作用导致赋存形态、生物可利用性的变化可能是CKDu致病的重要原因。针对以上问题,提出“吸附-除F-软化-NF-消毒”的处理策略,通过有机物吸附处理、阴离子交换除F、软化除硬分离预处理及NF深度处理等技术有效解决地下水中DOM、F⁻、Ca²⁺和Mg²⁺超标的问题,实现饮用水的供给。本研究全面分析了CKDu病区地下水中的污染物组成,并提出解决策略,可为斯里兰卡饮用水安全保障提供支撑。     

Song rates of dark-eyed juncos do not increase when females are fertile

Frequency of singing by birds may vary with reproductive stage in ways that reflect variation in the functions of song in intersexual and intrasexual communication. In dark-eyed juncos (Junco hyemalis) high-amplitude song is produced only by males. To investigate the function of this song, we tested whether fertility of females affected singing by their mates or by neighboring males. Using focal observations, song censuses, and radiotracking data, we determined whether song production varied between and among periods when females were fertile and non-fertile. Our findings show that males do not increase song production when their mates are fertile, nor do they increase song production when neighboring females are fertile. These results suggest that male juncos do not signal their intent to defend territories (or mates) more when females are fertile and that they do not use song to advertise to specific potential participants in extra-pair fertilizations. Received: 13 February 1997 / Accepted after revison: 2 May 1997     

The simultaneous stripping of arsenic and selenium from wastewaters using hollow-fibre supported liquid membranes

The extraction of total arsenic and selenium using hollow-fibre supported liquid membranes (HFSLMs), with specific interest in the optimal conditions for the extraction in wastewater, is reported. The extraction time, type of liquid membrane, sample and donor pH and stirring rate were optimised, and thereafter, the developed method was tested in real wastewater samples. The optimal HFSLMs adopted, after optimisation tests, comprised of Aliquat 336, 0.8 M NaOH, 200 rpm and 80 min as the extractant, stripping phase, stirring rate and reaction time, respectively. The developed method had reasonable-to-high extraction efficiencies in real wastewater samples with the final effluent recording as high as 73 and 78 % removal efficiencies for Se and As, respectively. Considering the initial concentrations found in the samples, use of this developed method could bring down the concentrations to levels admissible by the United States Environmental Protection Agency (US-EPA) and World Health Organisation (WHO).     

Ion-imprinted polymers for environmental monitoring of inorganic pollutants: synthesis, characterization, and applications

Ion imprinting has become one of the fast-growing technologies that have gained a lot of attention recently especially in the area of materials science. One of them is called the ion-imprinted polymers (IIPs). The IIPs are synthesized on the principles of enzyme phenomenon whereby a polymer is altered by a polymerization that takes place in the presence of a template that will be later removed to create cavities that will recognize only the analyte of interest. This specific and selective affinity for the target species decreases the chances of competition with other different types of ions. The imprinting technique started with the discovery of the bulk polymerization method where by the monomer, initiator, crosslinker, and template are mixed together and allowed to polymerize, and then the resulting polymer is ground and sieved to get particles with sizes suitable for the polymer's application. The IIPs have got some attractive qualities for use in environmental applications which include their stability and inexpensiveness and have a wide range of synthesis options with each suiting a certain unique application. Apart from environmental work, IIPs have applications in many other areas such as in membranes, in drug delivery, and in biosensors as alternatives to antibodies just to mention a few. This review focuses on the synthesis, types of imprinting, characterization, and applications of IIPs.     

Investigating the chromium status,heavy metal contamination,and ecological risk assessment via tannery waste disposal in sub-Saharan Africa (Kenya and South Africa)

Environmental Science and Pollution Research - To mitigate the negative environmental and public health concerns associated with increased industrial discharges amid the rapid industrial growth,...