Screening and optimization of media constituents for decolourization of Mordant Blue-9 dye by Phanerochaete chrysosporium

Decolourization of Mordant Blue-9 (MB-9) by the white-rot fungi Phanerochaete chrysosporium MTCC 787 was investigated by screening and optimization of the media constituents used for growing the fungus. Both % decolourization and specific removal of MB-9 by the fungus were taken as the responses to screen and optimize the media constituents using statistically valid Plackett–Burman and response surface methodology (RSM) design of experiments, respectively. Amongst the media constituents screened, glucose, veratryl alcohol, KH₂PO₄ and CaCl₂ were selected as the most important (P value < 0.05) media constituents for MB-9 dye decolourization; the other media constituents, viz. MgSO₄, tween 20, NH₄Cl₂ and inoculum size were, however, found to be insignificant in the study. Central composite design followed by RSM used in optimizing the important media constituents for enhancing the decolourization of MB-9 dye revealed optimum combinations of glucose, 13.46 g l⁻¹; veratryl alcohol, 9.30 mM; KH₂PO₄, 24.52 g l⁻¹; CaCl₂, 2.18 g l⁻¹; MgSO₄, 9.89 g l⁻¹; NH₄Cl₂, 4.68 g l⁻¹; tween 20, 0.050% and inoculum size, 0.8 OD₆₅₀, which gave a maximum % dye decolourization of 100% and specific dye removal of 0.1571 mg U⁻¹.     

Enhancing stress corrosion cracking resistance in Al-Zn-Mg-Cu-Zr alloy through inhibiting recrystallization

The aim of the work was to inhibit recrystallization in Al-Zn-Mg-Cu-Zr alloy and to evaluate the stress corrosion cracking (SCC) behavior of the alloy in the peak aged condition. For this purpose, scandium addition was made to an Al-Zn-Mg-Cu-Zr alloy as the former inhibits recrystallization. The scandium-containing alloy was heat-treated to peak aged condition and compared with the base peak aged alloy which contained recrystallized grains. The SCC susceptibilities of the alloys were evaluated using slow strain rate testing (SSRT) and U-bend techniques. While, the base alloy having recrystallized grains showed drastic loss in ductility in the corrosive environment (3.5 wt.% NaCl solution), the scandium-containing alloy having un-recrystallized and fine grains showed no significant loss in ductility in the similar environment. The fracture surface analysis revealed typical intergranular cracking of recrystallized grains in the base alloy, whereas in the scandium-containing alloy predominant ductile failure was observed. Thus, the study clearly indicated that inhibiting recrystallization in Al-Zn-Mg-Cu-Zr alloy through scandium addition, the SCC resistance of the alloy can be substantially improved even in the peak aged condition.     

Biomedical Nanomagnetics: A Spin Through Possibilities in Imaging, Diagnostics, and Therapy

Biomedical nanomagnetics is a multidisciplinary area of research in science, engineering and medicine with broad applications in imaging, diagnostics and therapy. Recent developments offer exciting possibilities in personalized medicine provided a truly integrated approach, combining chemistry, materials science, physics, engineering, biology and medicine, is implemented. Emphasizing this perspective, here we address important issues for the rapid development of the field, i.e., magnetic behavior at the nanoscale with emphasis on the relaxation dynamics, synthesis and surface functionalization of nanoparticles and core-shell structures, biocompatibility and toxicity studies, biological constraints and opportunities, and in vivo and in vitro applications. Specifically, we discuss targeted drug delivery and triggered release, novel contrast agents for magnetic resonance imaging, cancer therapy using magnetic fluid hyperthermia, in vitro diagnostics and the emerging magnetic particle imaging technique, that is quantitative and sensitive enough to compete with established imaging methods. In addition, the physics of self-assembly, which is fundamental to both biology and the future development of nanoscience, is illustrated with magnetic nanoparticles. It is shown that various competing energies associated with self-assembly converge on the nanometer length scale and different assemblies can be tailored by varying particle size and size distribution. Throughout this paper, while we discuss our recent research in the broad context of the multidisciplinary literature, we hope to bridge the gap between related work in physics/chemistry/engineering and biology/medicine and, at the same time, present the essential concepts in the individual disciplines. This approach is essential as biomedical nanomagnetics moves into the next phase of innovative translational research with emphasis on development of quantitative in vivo imaging, targeted and triggered drug release, and image guided therapy including validation of delivery and therapy response.     

Effects of low-level chlorination on zebra mussel,Dreissena polymorpha

Mortality pattern of different size groups (5-20 mm shell lengths) of the zebra mussel Dreissena polymorpha (Pallas), was studied in the laboratory under different chlorine concentrations (0.25-3.0 mgl(-1)). Results showed that exposure time for 100% mortality of mussels significantly decreased with increasing chlorine concentration. For example, mussels in the 10mm size group exposed to 0.25mg l(-1) chlorine residual took 1080h to reach 100% mortality whereas those exposed to 3 mg l(-1) chlorine took 252 h. All size groups (between 5 and 20 mm shell length) took identical exposure time to reach 100% mortality at given chlorine concentration (between 1 and 3mg l(-1)). The effect of acclimation temperature on D. polymorpha mortality in the presence of chlorine was significant. For example, 1026 h is required to reach 95% mortality using 0.5mg l(-1) residual chlorine at 10 degrees C, compared to 456h at 0.50 mg l(-1) chlorine and 25 degrees C. Resistance of D. polymorpha to chlorine appeared to be lower than that for other mussel species in The Netherlands viz., Mytilus edulis L. and Mytilopsis leucophaeata (Conrad). The present study also suggests that 100% mortality data for European populations of D. polymorpha at different chlorine concentrations are similar to those for the North American populations.     

Characterization and Mechanical Performance of the Mg-Stabilized β-Ca3(PO4)2 Prepared from Mg-Substituted Ca-Deficient Apatite

The preparation of Mg-stabilized β-tricalcium phosphate (β-TCP) was carried out by an aqueous precipitation method and the characterization of the powders was performed by powder X-ray diffraction, FT-IR spectra, Raman spectroscopy, and elemental analysis. The transformation of calcium-deficient apatite into β-TCP has occurred in the range of 700°–800°C. The calculated values for lattice parameters confirm the stabilization role played by Mg. The thermal stability of the Mg-stabilized β-TCP powders was evident until 1400°C, thus broadening the sintering temperature range without transformation into the undesirable α-TCP. Accordingly, the mechanical properties of the Mg-stabilized β-TCP were improved in comparison with those of pure β-TCP.     

Perfluorinated compounds in the plasma of loggerhead and Kemp's ridley sea turtles from the southeastern coast of the United States

Perfluorinated compounds (PFCs) have been measured in blood of humans and wildlife and are considered globally distributed contaminants. We examined 12 PFCs in the plasma of 73 loggerhead sea turtles (Caretta caretta) and 6 Kemp's ridley sea turtles (Lepidochelys kempii) captured from inshore waters of Core Sound, North Carolina (NC), and offshore waters of South Carolina, Georgia, and Florida (SC-FL). Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the dominant compounds, with respective mean concentrations of 11.0 ng/mL and 3.20 ng/mL for loggerhead turtles and 39.4 ng/mL and 3.57 ng/mL for Kemp's ridley turtles. Mean PFOS concentrations were 2- to 12-fold higher than typical mean sigmaPCB concentrations (approximately 5 ng/g wet mass) measured previously in sea turtle blood. More than 79% of the samples had detectable levels of perfluorocarboxylates (PFCAs) with 8-12 carbons, whereas only 17% or less of samples had detectable levels of PFCAs with 6 or 7 carbons. No samples had detectable levels of PFCAs with 4 or 5 carbons. In loggerhead turtles, sigmaPFC concentrations were not influenced by sex (p > 0.05), but were higher in turtles captured from inshore waters of NC than in turtles from offshore waters of SC-FL (p = 0.009). A backward stepwise multiple regression model showed that sigmaPFC concentrations were (1) significantly higher in Kemp's ridley turtles than loggerhead turtles (p < 0.0001), (2) higher in larger turtles (p = 0.018; carapace length used as a proxy for age), and (3) higher in turtles captured toward the north (p = 0.006). These findings suggest that bioaccumulation of PFCs in sea turtles is influenced by species, age, and habitat.     

Photocurrent imaging of charge transport barriers in carbon nanotube devices

The realization of high-performance electrical devices incorporating single-wall carbon nanotubes critically depends on the minimization of charge transport barriers in the tubes and at the contacts. Herein we demonstrate photocurrent imaging as a fast and effective tool to locate such barriers within individual metallic nanotubes contacted by metal electrodes. The locally induced photocurrents directly reflect the existence of built-in electric fields associated with the presence of depletion layers at the contacts or structural defects along the tubes.     

Optical TDM sorting networks for high-speed switching

The general time-space-time switching problem in telecommunications requires the use of multichannel time slot interchangers. We propose two multichannel time slot sorters which sort N² time-division multiplexed (TDM) optical inputs, arranged as N frames with N time slots per frame using O(Nlog²N) optical switch elements. The TDM optical inputs are sorted in place without expanding the space-time fabric into a space-division switch. The hardware components used are 2×2 optical switches (LiNbO₃ directional couplers) and optical delay lines connected in a feedforward fashion. Two space-time variants of the spatial odd-even merge algorithm are used to design the sorters. By maintaining the number of shift-exchange operations invariant at each stage, the proposed sorters use fewer switches than previously proposed sorters using switches with feedback line delays. The use of local control at each 2×2 switch makes the proposed sorters more practical for high-speed optical inputs than Benes-based time slot permuters with global control and high latency, which affects interframe distance. Both time slot sorters support pipelining of input frames and sorted outputs are available at each time slot after an initial frame delay. The proposed sorters find practical application in the time-domain equivalents of space-division, nonblocking, self-routing packet switches using the sort-banyan architecture, such as the Starlite switch, Sunshine switch, etc