1, 5-Bis (2-hydroxyacetophenone)thiocarbohydrazone: A novel colorimetric and fluorescent dual-mode chemosensor for the recognition of fluoride

1,5-Bis (2-hydroxyacetophenone)thiocarbohydrazone (H₄L) has been synthesized and characterized by means of spectroscopic and single crystal X-ray diffraction methods. Interactions of the H₄L with a variety of anions were investigated using a combination of UV–visible and fluorescence spectroscopic methods in a biological competing solvent DMSO. The H₄L has a high degree of selectivity for fluoride over other anions. ¹H NMR titration experiments indicate that a deprotonation process is involved in the chemo sensing process.     

Conducting cryogel scaffold as a potential biomaterial for cell stimulation and proliferation

The aim of the study was to demonstrate the potential of the cryogelation technique for the synthesis of the conducting cryogel scaffolds which would encompass the advantages of the cryogel matrix, like the mechanical strength and interconnected porous network as well as the conductive properties of the incorporated conducting polymeric material, polypyrrole. The cryogels were synthesized using different combinations of oxidizing agents and surfactants like, sodium dodecyl sulfate (SDS)/ammonium persulfate (APS), SDS/iron chloride (FeCl₃), cetyl trimethyl ammonium bromide (CTAB)/APS, and CTAB/FeCl₃. The synthesized gels were characterized by scanning electron microscopic analysis for morphology, Fourier transform infrared spectroscopy for analyzing the presence of the polypyrrole (0.5–4 %) as nano-fillers in the gel. It was observed that the presence of these nano-fillers increased the swelling ratio by approximately 50 %. The synthesized conducting cryogels displayed high stress bearing capacity without being deformed as analysed by rheological measurements. The degradation studies showed 12–15 % degradation in 4 weeks time. In vitro studies with conducting and non-conducting cryogel scaffold were carried out to optimize the stimulation conditions for the two cell lines, neuro2a and cardiac muscle C2C12. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed approximately 25 and 15 % increase in the cell proliferation rate for neuro2a and C2C12 cell line, respectively. This was observed at a specific voltage of 100 mV and 2 V, for a specified duration of 2 h and 1 min, respectively for the conducting scaffold as compared to the control. This can play an important role in tissue engineering applications for cell lines where acquiring a high cell number and functionality is desired.     

Mechanisms for naphthalene removal during electrolytic aeration

Batch tests were performed to investigate chemical and physical processes that may result during electrolytic aeration of a contaminated aquifer using naphthalene as a model contaminant. Naphthalene degradation of 58-66% took place electrolytically and occurred at the same rates at a pH of 4 and 7. 1,4-naphthoquinone was identified as a product of the electrolysis. Stripping due to gases produced at the electrodes did not result in any naphthalene loss. Hydrogen peroxide (which may be produced at the cathode) did not have any effect on naphthalene, but the addition of ferrous iron (which may be present in aquifers) resulted in 67-99% disappearance of naphthalene. Chlorine (which may be produced from the anodic oxidation of chloride) can effectively degrade naphthalene at pH of 4, but not at a pH of 7. Mono-, di- and poly chloronaphthalenes were identified as oxidation products. Ferric iron coagulation (due to the oxidation of ferrous iron) did not significantly contribute to naphthalene loss. Overall, electrolytic oxidation and chemical oxidation due to the electrolytic by-products formed are significant abiotic processes that could occur and should be accounted for if bioremediation of PAH-contaminated sites via electrolytic aeration is considered. Possible undesirable products such as chlorinated compounds may be formed when significant amounts of chlorides are present.     

Effect of Cryogenic Pre-Treatment on Breakage Characteristics of Rocks

Improvement of energy efficiency in comminution of rocks using various pretreatment methods is being explored worldwide. This paper presents experimental data on breakage characteristics of granite and sandstone using cryogenic pre-treatment. The samples were treated with varying duration of immersion in liquid nitrogen. Combined pretreatment using oven heating followed by quenching in liquid nitrogen were also explored. The results indicate that using cryogenic pretreatment uniaxial tensile strength of granite can be decreased by more than 40% while in uniaxial compressive strength about 28% reduction is possible. For sandstone as much as 33% reduction in uniaxial compressive strength was observed.

     

Process performance and change in sludge characteristics during anaerobic digestion of sewage sludge with ozonation.

A new process configuration combining anaerobic digestion with ozonation, and operated at long SRT, was studied with the objective of on-site reduction in sludge quantity and improving biogas recovery. The process performance with respect to solid reduction efficiency and other important process parameters like accumulation of inorganic solids, changes in sludge viscosity and dewatering characteristics were evaluated from the data of long term pilot scale continuous experiments conducted using a mixture of primary and secondary municipal sewage sludge. Due to sludge ozonation and long SRT, high VSS degradation efficiency of approximately 80% was achieved at a reactor solid concentration of 6.5%. A high fraction of inorganic solid (>50%) consisting mainly of acid insoluble and iron compounds was found to accumulate in the reactor. The high inorganic content accumulated in the digested sludge did not, however, contribute to the observed increase in sludge viscosity at high solid concentration. The sludge viscosity was largely found to depend on the organic solid concentration rather than the total solid content. Moreover, higher inorganic content in the digested sludge resulted in better sludge dewaterability. For a quick assessment of the economic feasibility of the new process, an economic index based on the unit cost of digested sludge disposal to unit electric cost is proposed.