Poly (vinyl alcohol)/poly (acrylamide‐ co ‐diallyldimethyl ammonium chloride) semi‐IPN hydrogels for ciprofloxacin hydrochloride drug delivery

Herein, the authors developed a new and potential semi‐interpenetrating polymer network (semi‐IPN) hydrogels of poly vinyl alcohol (PVA), acryl amide and diallyldimethyl ammonium chloride employing chemical cross‐linker N, N''‐methylene bisacrylamide (NNMBA) and ammonium persulphate as an initiator by radical polymerisation. To analyse the copolymer formation between two monomers and IPN cross‐linking reaction, the resulting hydrogel was characterised by Fourier transform infrared spectroscopy and the surface morphology was analysed using scanning electron microscopy. Differential scanning calorimetry and X‐ray diffraction studies were also carried out for investigating drug loading and distribution and swelling experiments were carried out for the uptake of water. In vitro release of ciprofloxacin hydrochloride from hydrogel was performed at intestinal conditions. The amount of PVA, NNMBA and total monomer concentration was found to strongly control the drug release behaviour from the hydrogels.Inspec keywords: hydrogels, polymer blends, biomedical materials, drug delivery systems, polymerisation, Fourier transform infrared spectra, surface morphology, scanning electron microscopy, differential scanning calorimetry, X‐ray diffraction, swelling, biological organs, ammonium compoundsOther keywords: PVA‐poly(acrylamide‐co‐diallyldimethyl ammonium chloride) semiIPN hydrogels, ciprofloxacin hydrochloride drug delivery, semiinterpenetrating polymer network hydrogels, polyvinyl alcohol, acryl amide, diallyldimethyl ammonium chloride, chemical crosslinker N,N''‐methylene bisacrylamide, ammonium persulphate, radical polymerisation initiator, NNMBA, copolymer formation, IPN crosslinking reaction, Fourier transform infrared spectroscopy, surface morphology, scanning electron microscopy, differential scanning calorimetry, X‐ray diffraction, drug loading, drug distribution, swelling, water uptake, in vitro ciprofloxacin hydrochloride release, intestinal conditions, total monomer concentration, drug release behaviour     

Removal of sulfide in integrated anaerobic–aerobic wastewater treatment system

In recent years, the stipulations fixed by regulatory bodies have become stringent to keep environmental pollution under control. Normally COD and BOD are the parameters monitored to determine the efficiency of any treatment system. But in many cases, industrial wastewater may contain sulfate along with other organic constituents. Sulfate, if present in the wastewater, will be converted to H₂S under anaerobic conditions and this is hazardous. Subsequently, if the same wastewater is treated under aerobic conditions, a part of the air supplied will be utilized for oxidation of sulfide back to sulfate which leads to reduced efficiency of the aerobic treatment. The released wastewater with high sulfate levels will be going into the environment, which is undesirable. Methods are reported in the literature for the removal of sulfate and sulfide before and after anaerobic treatment respectively. Most of these methods are chemical which are either costly or impracticable. Therefore, a novel approach for removing sulfate or sulfide in the treatment scheme is required. In the present communication, studies are undertaken by designing an innovative stripper system where sulfide is removed to the extent of 60 to 70% before aerobic treatment. The parameters involved in design and operation of the stripper, such as airflow rate, liquid flow rate, liquid to air ratio, and pH profile, are optimized. It is a physical system in which air and waste water are passed as counter currents. The treated wastewater from the stripper, which contains less sulfide, may be post-treated in the aerobic system before final discharge. Hydrogen sulfide can be efficiently removed by coupling this type of stripper to existing anaerobic systems. The system can be efficiently used in existing treatment plants or in new designs to control sulfide (free sulfide generated in an anaerobic reactor in the case of wastewaters having high sulfate inhibits methanogenesis, resulting in reduced performance of the anaerobic process) generated in anaerobic reactors and to optimize the air and oxygen requirements in the aerobic system.     

Nanostructured Carbon Nitrides for CO2 Capture and Conversion

Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO₂ capture and its reduction into clean and green low-carbon fuels and valuable chemical feedstock by using sustainable and intermittent renewable energy sources of sunlight and electricity through the heterogeneous photo(electro)catalysis. Here, the latest research results in this field are summarized, including implementation of novel functionalized nanostructured CNs and their hybrid heterostructures in meeting the stringent requirements to raise the efficiency of the CO₂ reduction process by using state-of-the-art photocatalysis, electrocatalysis, photoelectrocatalysis, and feedstock reactions. The research in this field is primarily focused on advancement in the synthesis of nanostructured and functionalized CN-based hybrid heterostructured materials. More importantly, the recent past has seen a surge in studies focusing significantly on exploring the mechanism of their application perspectives, which include the behavior of the materials for the absorption of light, charge separation, and pathways for the transport of CO₂ during the reduction process.     

Laminar compressible MHD (magneto hydro dynamic) boundary layers

A laminar compressible magnetohydrodynamic boundary layer flow over a flat-plate has been examined. The effects of electromagnetic fields on the boundary layers are presented.     

Binding of mouse and rabbit iron-59 transferrins to lactating mouse mammary epithelial cells.

The binding of mouse and rabbit transferrins to lactating mouse mammary epithelial cells was tested in a 59Fe-protein-binding assay. The homologous and heterologous binding was slow during the first 30 min, after which the uptake steadily increased. In ligand concentration-dependent saturation studies, the heterologous rabbit protein showed a high degree of binding and required approximately 9.7 ng of ligand to saturate approximately 2 x 10(6) cells. The homologous mouse protein demonstrated a low degree of binding and failed to demonstrate saturation at the above ligand concentration. Scatchard plot for homologous binding data was nonlinear and implied a low (1.08 x 10(-10) M) and a high (1.82 x 10(-9) M) affinity interaction mechanism. However, the plot for heterologous binding was linear and characterized by one high affinity (1.0 x 10(-9) M) binding interaction. A total of 11,000 and 19,600 binding sites per cell were estimated for mouse and rabbit proteins, respectively. These data suggest a binding crossreactivity between mouse and rabbit transferrins. A high affinity binding mechanism seems to be conserved in proteins from both species; however, an additional low affinity binding was present only in the homologous system.     

The development of risk assessment models for carpal tunnel syndrome: a case-referent study

The present study developed risk assessment models for carpal tunnel syndrome (CTS) which can provide information of the likelihood of developing CTS for an individual having certain personal characteristics and occupational risks. A case-referent study was conducted consisting of two case groups and one referent group: (1) 22 work-related CTS patients (W-CTS), (2) 25 non-work related CTS patients (NW-CTS), and (3) 50 healthy workers (HEALTHY) having had no CTS history. The classification of CTS patients into one of the case groups was determined according to the type of insurance covering their medical costs. Personal characteristics, psychosocial stresses at work, and physical work conditions were surveyed by using a questionnaire tailor-designed to CTS (reliability of each scale > or = 0.7). By contrasting the risk information of each case group to that of the referent group, three logistic regression models were developed: W-CTS/HEALTHY, NW-CTS/HEALTHY, and C-CTS/HEALTHY (C-CTS, the combined group of W-CTS and NW-CTS). ROC analysis indicated that the models have satisfactory discriminability (d' = 1.91 to 2.51) and high classification accuracy (overall accuracy = 83-89%). Both W-CTS/HEALTHY and C-CTS/HEALTHY include personal and physical factors, while NW-CTS/HEALTHY involves only personal factors. This suggests that the injury causation of NW-CTS patients should be attributable mainly to their 'high' personal susceptibility to the disorder rather than exposure to adverse work conditions, while that of W-CTS patients be attributable to improper work conditions and CTS-prone personal characteristics in combination.     

X-ray absorption and micro X-ray fluorescence spectroscopy investigation of copper and zinc speciation in biosolids

Despite its pivotal role in determining the risks and time frames associated with contaminant release, metal speciation remains a poorly understood aspect of biosolids chemistry. The work reported here used synchrotron-based spectroscopy techniques to investigate the speciation of copper and zinc in a range of Australian biosolids. High resolution element mapping of biosolids samples using micro X-ray fluorescence spectroscopy revealed considerable heterogeneity in key element associations, and a combination of both organic and inorganic copper and zinc binding environments. Linear combination fitting of K-edge X-ray absorption spectra indicated consistent differences in metal speciation between freshly produced and stockpiled biosolids. While sulfide minerals play a dominant role in metal binding in freshly dewatered biosolids, they are of lesser importance in dried biosolids that have been stockpiled. A degree of metal binding with iron oxide minerals was apparent but the results did not support the hypothesis that biosolids metals are chiefly associated with iron minerals. This work has potential implications for the long-term stability of metals in biosolids and their eventual fate following land application.