Solid state fermentation of lipopeptide antibiotic iturin A by using a novel solid state fermentation reactor system

A new solid state fermentation reactor (SSFR) for solid substrate was used for the production of lipopeptide antibiotic iturin A using Bacillus subtilis RB14-CS. Solid state fermentation (SSF) is the technique of cultivation of microorganisms on solid and moist substrates in the absence of free water. SSF has shown much promise in the development of several bioprocesses and products because of their several advantages like absence of free water that allows simplified downstream processing and low cost. SSFR allows agitation of the SSF culture with improved temperature control and air supply. Interestingly, when okara, the widely available waste product from the tofu industries, was used as the solid substrate for the SSFR, no iturin A production was observed. However, without agitation, production of iturin A was observed in the SSFR but the production level remained low. The low production of iturin A was found to be due to the heat generation and excess temperature rise inside the reactor system during the fermentation process. Maintaining the temperature within a range of 25–30°C, production of iturin A was significantly improved in the SSFR. This was comparable to the laboratory scale production, and signifies the potential application of the SSFR for SSF.     

Modeling carbon sequestration under zero-tillage at the regional scale. II. The influence of crop rotation and soil type

For policy decisions with respect to CO₂-mitigation measures in the agricultural sector, national and regional estimations of the efficiency of such measures are required. The conversion of ploughed cropland to zero-tillage is discussed as an option to reduce CO₂ emissions and promises at the same time effective soil and water conservation. Based on the upscaling of simulation results with the soil and land resources information system SLISYS-BW, estimations of CO₂-mitigation rates in relation to crop rotations and soil type have been made for the state of Baden-Württemberg (Germany). The results indicate considerable differences in the CO₂-mitigation rates between crop rotations ranging from 0.48 to 0.03 Mg C ha⁻¹ a⁻¹ for winter cereals–spring cereals–rape rotations and winter cereals–spring cereals–corn silage rotations, respectively. The efficiency of the crop rotations is strongly related to the total carbon input and in particular the amount of crop residues. Among the considered soil types, highest CO₂-mitigation rates are associated with Cumulic Anthrosols (0.62 Mg C ha⁻¹ a⁻¹) and the lowest with Gleysols (−0.01 Mg C ha⁻¹ a⁻¹). An agricultural extensification scenario with conventional plowing but conversion of the presently applied intensive crop rotations to a clover–clover–winter cereals rotation indicated a CO₂-mitigation potential of 466 Gg C a⁻¹. However, the present high market prices for cereals and increasing demand for energy production from biomass encourages an intensification of the agricultural production and an excessive removal of biomass which in future will seriously reduce the potential for carbon sequestration on cropland.     

Large eddy simulation of dispersion around an isolated cubic building: evaluation of localized dynamic k_\mathrm{SGS}-equation sub-grid scale model

In the present study, the prediction accuracy of a dynamic one-equation sub-grid scale model for the large eddy simulation of dispersion around an isolated cubic building is investigated. For this purpose, the localized dynamic $k_\mathrm{SGS} $ -equation model (LDKM) is employed and the results are compared with the available experimental data and two other classic sub-grid scale models, namely, standard Smagorinsky–Lilly model (SSLM) and dynamic Smagorinsky–Lilly model (DSLM). It is shown that the three SGS models give results in good agreement with experiment. However, near the ground level of the leeward wall, dimensionless time-averaged concentration, $\langle K\rangle $ , profile is not quite similar to the experimental data. It is also demonstrated that the LDKM predicts the values of $\langle K\rangle $ on the roof, leeward and side walls more acceptably than the SSLM and DSLM. Whereas, the streamwise elongation of time-averaged structures of the plume shape is more over-estimated with the LDKM than with the other two SGS models. In terms of numerical difficulty, the LDKM is found to be stable and computationally reasonable. In addition, it does not suffer from a flow dependent constant such as the Smagorinsky coefficient employed in the SSLM model.     

Mid-depth oil concentration due to vertical oil dispersion in a regular wave field

An experimental program is organized to investigate the vertical oil dispersion of surface oil spills in a regular wave field. Various waves characteristics and different volumes of oil spills are tested to assess the oil concentration variations at two sampling stations. It is found that the oil concentration due to vertical oil dispersion follows an ascending diagram to reach a maximum and then decreases while oil slick passes the location. The maximum mid-depth oil concentration (C_max) at the farther sampling station is 30–50 % less than the concentration at the closer sampling station to the spill location. A 50 % increase in oil spill volume causes 30–60 % growth in oil concentrations. The relations between oil concentration and important parameters such as wave characteristics, amount of spilled oil and the distance of sampling stations from the spill location are indicated and also oil concentration variations are quantified. Two equations are derived through statistical analysis of the obtained experimental data, which estimate the magnitude and time of maximum oil concentration.     

Sonocatalytic degradation of tetracycline antibiotic in aqueous solution by sonocatalysis

Tetracycline (TC), one of the most common antibiotics, is often poorly bio-degraded in conventional wastewater treatment plants. In this study, the sonocatalytic degradation of TC was investigated using TiO₂ nano-particles as catalyst. The effect of pH, initial TC concentrations, reaction times, and H₂O₂ concentrations were evaluated. The efficacy of ultrasonic irradiation alone in the removal of this pollutant was negligible but removal efficiency increased upon addition of TiO₂ up to 250 mg L^?1; increase of pH and initial TC concentration attenuated TC degradation. Addition of H₂O₂ raised the removal efficiency so that complete removal of TC was achieved within 75 min.     

The Toxicology of Silica Nanoparticles: A Review

Silica nanoparticles are increasingly used in industrial, cosmetics, and medical applications. Workers in nanosilica production industries, laboratory personnel in drug production industries, patients taking drugs with nanosilica in its formulations, and everyone in society who uses cosmetics are potentially at risk to health effects induced by silica nanoparticles. Like other nanomaterials, nanosilica has unique physical and chemical properties that modify its toxic effects compared to bulk silica or microparticles of silica. Nanosilica toxicology has been studied by various in vitro and in vivo protocols and on humans, studies which are collected and summarized in the present publication. The toxic effects are outlined based on the type of body compartment, viz. cardiovascular, dermal, respiratory, neural, hepatic, genetic, immune, reproductive, and renal system. Further information, especially the experimental protocols and toxicological endpoints, are summarized in tables.     

Synthesis and antithyroid activity of 6‐n‐propyl‐5‐arylazo‐2‐thiouracils †

The synthesis of several 6‐n‐propyl‐5‐arylazo‐2‐thiouracil derivatives was achieved. The antithyroid activity of these derivatives has been determined using iodine‐125‐thiocyanate discharge technique in rats, and 6‐n‐propyl‐2‐thiouracil (PTU) as a standard. None of the 5‐arylazo‐2‐thiouracil analogs showed antithyroid activity as compared to PTU. The structure‐activity relationships (SAR) of position 5 in the PTU molecule and the requirements for better binding to the proposed receptor are discussed.     

Prevalence of anaemia among children living in five communities in and near Karachi,Pakistan

The primary objectives of this research were to estimate the prevalence of anaemia and low haematocrit among preschool children living in Karachi. Through a geographically stratified design, 349 children aged 36–60 months were selected, from five communities in and near Karachi. Blood samples were drawn from children and a questionnaire was administered to evaluate various demographic and socioeconomic characteristics. Chi-square test and multiple logistic regression procedures were used to compare the prevalence of anaemia and low haematocrit among various strata. The overall prevalence of anaemia and low haematocrit were 55.9 and 48.4%, respectively. Children living in the rural community had the highest prevalence of anaemia (78.7%) and low haematocrit (63.8%). Children aged 36–48 months had also higher prevalence of anaemia and low haematocrit. Children's nutritional status was significantly associated with both anaemia and low haematocrit. We recommend appropriate interventions to reduce the burden of these conditions in Pakistan.