The facile synthesis, characterization and evaluation of photocatalytic activity of bimetallic FeBiO3 in natural sunlight exposure

In an effort to develop sunlight active photocatalysts for environmental remediation, a phase pure bimetallic oxide, FeBiO₃, was synthesized by a facile route.

Synthesis, characterization and visible light photocatalytic activity of Cr3+, Ce3+and N co-doped TiO2for the degradation of humic acid

The synthesis, characterization and photocatalytic activity of Cr³⁺and Ce³⁺co-doped TiON (N-doped TiO₂) for the degradation of humic acid with exposure to visible light is reported.

Enhanced photocatalytic activity of V₂O₅-ZnO composites for the mineralization of nitrophenols

In an effort to enhance the photocatalytic activity of ZnO in natural sunlight, V2O5-ZnO nanocomposites were synthesized by co-precipitation technique. The characterization of the synthesized powders by FESEM, XRD and UV-visible diffuse reflectance spectroscopy (DRS) revealed that the both V2O5 and ZnO retain their individual identity in the composites but the increasing concentration of V2O5 affect the particle size of ZnO. As estimated by photoluminescence spectroscopy, in comparison to pure ZnO, the presence of V2O5 significantly suppressed the charge carrier's recombination process. The photocatalytic activity of the synthesized powders was evaluated for the degradation/mineralization of three potential nitrophenol pollutants (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol). The synthesized composites showed significantly higher activity for both degradation and mineralization of nitrophenols compared to pure ZnO. The progress of the degradation process was evaluated by HPLC while mineralization was monitored by TOC analysis. The degradation/mineralization route was estimated by identifying the intermediates using GC-MS. The correlation of the experimental data revealed that the position of NO2 group in 2- and 4-nitrophenol significantly affect the rate of degradation. The identification of hydroxyl group containing intermediates in the degradation of 4-NP confirmed the formation and vital role of hydroxyl radicals in degradation process. The rapid mineralization of nitrophenol substrates pointed out superoxide anions as major contributors in degradation and mineralization process. The assessment of the release of relevant ions (NO2(-), NO3(-), ONOO(-) and NH4(+)) during the degradation process assisted in identifying the plausible interaction sites.

Morphology controlled bulk synthesis of disc-shaped WO3 powder and evaluation of its photocatalytic activity for the degradation of phenols

The surfactant assisted synthesis of disc-shaped WO3 powder and its photocatalytic performance in sunlight exposure is reported. UV-vis DRS, XRD and FESEM characterized the synthesized WO3. The synthesized powder exhibited a bandgap of ∼2.55eV with cubic lattice and high crystallinity. The photocatalytic activity of the synthesized WO3 was examined for the degradation of phenol, resorcinol, 2-chlorophenol and 2-nitrophenol in complete spectrum and visible segment of sunlight. The highly efficient degradation/mineralization of 2-chloro and 2-nitrophenol compared to that of phenol and resorcinol, under identical experimental conditions, suggested the regulatory role of substituents attached to the aromatic ring in degradation/mineralization process. The time-scale HPLC degradation profiles, identification of intermediates by GC-MS and removal of organic carbon during the course of reaction were utilized to approximate the possible route of degradation/mineralization of phenolic substrates. The measurement of the anions released during the photocatalytic process was used to identify the nature of the major oxidants (O2(•-), OH(•)) and the possible interaction sites. A significant decrease in the photocatalytic activity of synthesized WO3, ∼50%, was observed in visible portion of sunlight however, a sustained activity was observed in the repeated exposures.

Novel p53 codon 240 Ser > Thr coding region mutation in the patients of oral squamous cell carcinoma (OSCC)

Chewing habits of tobacco, betel quid (paan), and betel nut (chhaliya) are common traditions in Pakistan. Different other preparations and combination of flavors with tobacco, paan, and chhaliya ingredients are commonly available in the market and have received considerable attention as sources of carcinogens that promote OSCC. Mutagens can damage DNA and generate promutagenic lesions. The germ line mutation/polymorphism of p53 gene has been reported to be involved in multiple steps of carcinogenesis. This study aims to find out the loss of TP53 functions due to mutation/polymorphism caused by genomic alteration and interaction with tobacco-related ingredients.Tissue and blood specimens from 260 OSCC patients were collected and compared with blood samples of 260 age- and sex-matched controls. Mutations in exons 2-11 of p53 gene were examined by PCR-SSCP and directly sequenced.A novel mutation was found in exon 7 of p53 gene. This mutation was observed in the tumors of the OSCC patients. The blood samples of the patients and the controls did not show the nucleotide change in this region. The "AGT" to "ACT" missense mutation was identified at position 719 at TP53. This results in the substitution of amino acid serine with threonine at codon 240 of p53 protein.This novel missence mutation in the DNA-binding domain indicated that the DNA structure may be damaged by the use of exogenous DNA-damaging agents, including tobacco-related carcinogens present in gutka, niswar, and manpuri, which may result in the loss of p53 protein function.

Synthesis, characterization and photocatalytic activity of Al₂O₃-TiO₂ based composites

The synthesis, characterization and photocatalytic performance of non-traditional Al₂O₃-TiO₂-based photocatalysts is reported. Al₂O₃-TiO₂ support was loaded with various fractions of CuO and ZrO₂. A sound agreement was observed between the bandgaps of synthesized powders measured by UV-Visible diffuse reflectance spectroscopy (DRS) in the solid phase and UV-Visible spectroscopy in the aqueous medium. X-ray diffraction (XRD) analysis revealed the composite nature of the catalysts with the retention of individual identity of each component. The average crystallite size of the individual component was found to be in the range of 20 to 40 nm. Scanning electron microscopy (SEM) analysis authenticated the presence of CuO and ZrO₂ at the surface of Al₂O₃-TiO₂ support, while Rutherford Back Scattering Spectroscopy (RBS) confirmed the quantity of the modifiers as per theoretical calculations. The composites showed an enhanced photocatalytic activity in sunlight compared to Al₂O₃-TiO₂ for the degradation of dyes. Efforts were made to elucidate the enhanced sunlight response of the synthesized composite catalysts compared to Al₂O₃-TiO₂. As monitored by ion chromatography (IC), the synthesized photocatalysts completely mineralized the dyes leaving behind inorganic ions in solution. The kinetics of photocatalytic degradation of dyes was evaluated for optimum correlation with the existing models. The stability of the photocatalysts against the photo-corrosion was monitored by analyzing the samples for respective metals in solution after sunlight exposure. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

Ce3+ impregnated ZnO: a highly efficient photocatalyst for sunlight mediated mineralization

The surface of pre-synthesized hexagonal ZnO was tailored by Ce³⁺ states.

The high strain-rate behaviour of selected tissue analogues

The high strain-rate response of four readily available tissue simulants has been investigated via plate-impact experiments. Comparison of the shock response of gelatin, ballistic soap (both sub-dermal tissue simulants), lard (adipose layers) and Sylgard(®) (a potential brain simulant) allowed interrogation of the applicability of such monolithic tissue surrogates in the ballistic regime. The gelatin and lard exhibited classic linear Hugoniot equations-of-state in the US-uP plane; while for the ballistic soap and Sylgard(®) a polymer-like non-linear response was observed. In the P/σX-v/v0 plane there was evidence of separation of the simulant materials into distinct groups, suggesting that a single tissue simulant is inadequate to ensure a high-fidelity description of the high strain-rate response of complex mammalian tissue. Gelatin appeared to behave broadly hydrodynamically, while soap, lard and Sylgard(®) were observed to strengthen in a material-dependent manner under specific loading conditions at elevated shock loading pressures/stresses. This strengthening behaviour was tentatively attributed to a further polymeric-like response in the form of a re-arrangement of the molecular chains under loading (a steric effect). In addition, investigation of lateral stress data from the literature showed evidence of operation of a material-independent strengthening mechanism when these materials were stressed above 2.5-3.0GPa, tentatively linked to the generically polymeric-like underlying microstructure of the simulants under consideration.

Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) depolymerase from Aspergillus sp. NA-25

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) degrading thermophilic fungus was isolated from soil sample collected from waste disposal site, Islamabad, Pakistan. It was able to grow efficiently on a medium containing PHBV as a sole source of carbon and has been identified as Aspergillus sp. NA-25 by 18S rRNA. Using 9% of inoculum maximum production of PHBV depolymerase was observed at 45 degrees C, pH 7.0 in the presence of 0.2% lactose as an additional carbon source. PHBV depolymerase was purified by precipitation with 80% ammonium sulfate and gel filtration chromatography on Sephadex G-75. The four enzyme forms obtained after gel filtration were analyzed on SDS-PAGE and their molecular weights (36, 68, 72 and 90 kDa) were determined. They were characterized on the basis of effect of different temperatures, pH, metal ions and different reagents on the PHBV activity and stability. It is obvious that the fungal strain Aspergillus sp. NA-25 is capable of degrading PHBV with the help of different types of depolymerases.

Degradation of polyisoprene rubber by newly isolated Bacillus sp. AF-666 from soil

Various microorganisms were screened for their ability to degrade polyisoprene rubber (natural rubber latex gloves). Strain AF-666, newly isolated from a soil sample, was selected as the best strain having the ability to grow on polyisoprene containing plates. The strain identified as Bacillus sp. AF-666, was found to degrade polyisoprene rubber, both on basal agar plates (latex overlay) as well as in liquid medium. Qualitative analysis of degradation was done through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy SEM showed changes in surface morphology, like appearance of pits and cracks, and marked difference in transmittance spectra of test and control due to changes in the functional groups, was detected through FTIR. CO2 evolution as a result of rubber degradation, was calculated gravimetrically by Sturm Test. About 4.43 g/1 of CO2 was produced in case of test, whereas, 1.57 g/1 in case of control. The viable number of cells (CFU/ml) was also higher in test than in control. Present study may provide an opportunity for further studies on the applications of biotechnological processes as a tool for rubber waste management.

Sero-epidemiology of peste des petits ruminants (PPR) in Pakistan

A sero survey was conducted during 2005-2006 to estimate the sero prevalence of PPR in the small ruminant population of Pakistan. A total of 2798 samples were collected including goats (1979) and sheep (819) from villages in 27 randomly selected districts. These were tested by cELISA for PPRV and true prevalence estimates were calculated by Rogan and Gladen estimator. Overall, 1273 (45.5%) were found positive; 980 (49.5%) of 1979 samples from goats and 293 (35.8%) of 819 serum samples from sheep were positive. The true sero-prevalence of PPR was estimated to be 48.5% (95% CI, 46.6-50.3), and 52.9% (95% CI, 50.7-55.1) and 37.7 (95% CI, 34.4-41.0) for goats and sheep, respectively. PPR virus is widely distributed all across Pakistan and has become an endemic infection of small ruminants. Since it is one of the leading causes of morbidity and mortality in small ruminants, it poses a serious threat to food security and the rural economy in Pakistan.

Characterization of a novel lipase from Bacillus sp. isolated from tannery wastes

Kinetics of a lipase isolated from Bacillus sp. was studied. The enzyme showed maximum activity at pH 9 and temperature 60°C. The Michaelis constant (KM 0.31 mM) obtained from three different plots i.e., Lineweaver-Burk, Hanes-Wolf and Hofstee, was found to be lower than already reported lipases that confirmed higher affinity of the enzyme for its substrate p-NPL (p-nitrophenyl laurate). Vmax of the enzyme was found to be 7.6 µM/mL/min. Energy of activation calculated from Arrhenius plot was found to be 20.607 kJmol(-1). Activation enthalpy (ΔH*) had negative trend and the value for the hydrolysis of p-NPL by the enzyme at optimum temperature was -2.748 kJmol(-1). Activation entropy (ΔS*) and free energy of activation (ΔG*) of the enzyme were found to be 1.468 Jmol(-1)K(-1) and -3.237 kJmol(-1), respectively at optimum temperature. Low value of Q10 (0.04788) shows high catalytic activity of the enzyme. Mn(2+), Fe(2+) and Mg(2+) enhanced the lipase activity whereas Cu(2+), Na(+) and Co(2+) inhibited the enzyme activity. However, the enzyme activity was not affected significantly by K(+) ions. EDTA and SDS also significantly inhibited the lipase activity. Activity of the enzyme was increased in n-hexane while decreased with increase in concentration of acetone, chloroform, ethanol and isopropanol.

Use of a pedicled flap for reconstruction of extensive soft tissue defects around elbow

OBJECTIVE

To determine the reliability of pedicled latissimus dorsi flap for reconstruction of extensive defects around the elbow in terms of flap survival and coverage of exposed bones, vessels or nerves.

STUDY DESIGN

Case series.

PLACE AND DURATION OF STUDY

Department of Plastic and Reconstructive Surgery at Shaikh Zayed Hospital, from February 2003 to January 2008.

METHODOLOGY

Patients with extensive traumatic wounds around the elbow and wounds secondary to release of postburn elbow contracture were included. Patients above 60 years of age with previous history of myocardial infarct, heart failure, chronic obstructive pulmonary disease or insulin dependent diabetes were excluded. Pedicled latissimus dorsi flap was used for defect reconstruction. Overall flap survival and postoperative complications were the outcome measures.

RESULTS

There were 28 patients, including 20 males and 8 females, age ranging from 17 to 60 years. Evaluation of the defect considering extent of tissue loss, depth of the defect and exposed vital structure was done. Myocutaneous flap was used in 4 (14%) patients. Muscle only flap was used in 24 patients (86%). Twenty five (90%) flaps survived completely and 3 (10%) had partial loss. Other minor complications were partial graft loss seen in 3 (10%) patients and wound infection seen in 2 (7%) patient. There was no considerable morbidity at donor site and all patients had satisfactory healing.

CONCLUSION

Pedicled latissimus dorsi flap is a reliable and safe option for resurfacing extensive soft tissue defects of arm, elbow and forearm.