Enzymatic saccharification and fermentation of paper and pulp industry effluent for biohydrogen production

Paper and pulp industry effluent was enzymatically hydrolysed using crude cellulase enzyme (0.8–2.2FPU/ml) obtained from Trichoderma reesei and from the hydrolysate biohydrogen was produced using Enterobacter aerogenes. The influence of temperature and incubation time on enzyme production was studied. The optimum temperature for the growth of T. reesei was found to be around 29 °C. The enzyme activity of 2.5 FPU/ml was found to produce about 22 g/l of total sugars consisting mainly of glucose, xylose and arabinose. Relevant kinetic parameters with respect to sugars production were estimated using two fraction model. The enzymatic hydrolysate was used for the biohydrogen production using E. aerogenes. The growth data obtained for E. aerogenes were fitted well with Monod and Logistic equations. The maximum hydrogen yield of 2.03 mol H₂/mol sugar and specific hydrogen production rate of 225 mmol of H₂/g cell/h were obtained with an initial concentration of 22 g/l of total sugars. The colour and COD of effluent was also decreased significantly during the production of hydrogen. The results showed that the paper and pulp industry effluent can be used as a substrate for biohydrogen production.     

Effect of the Strain Rate and Microstructure on Damage Growth in Aluminum

Materials used in soldier protective structures, such as armor, vehicles and civil infrastructures, are being improved for performance in extreme dynamic environments. Nanocrystalline metals show significant promise in the design of these structures with superior strengths attributed to the dislocation-based and grain-boundary-based processes as compared to their polycrystalline counterparts. An optimization of these materials, however, requires a fundamental understanding of damage evolution at the atomic level. Accordingly, atomistic molecular dynamics simulations are performed using an embedded-atom method (EAM) potential on three nano-crystalline aluminum atom systems, one a Voronoi-based nano-crystalline system with an average grain size of 10 nm, and the other two single crystals. These simulations are performed under the condition of uniaxial expansion at several strain rates ranging from 10⁶s^-1 to 10¹⁰s^-1. Results for the effective stress are discussed with the aim of establishing the role of the strain rate and microstructure on the evolution of the plastic strain and void volume fraction and the eventual loss of stress carrying capability of the atom systems.     

Influence of surface modification on the apatite formation and corrosion behavior of Ti and Ti-15Mo alloy for biomedical applications

Commercially pure Ti and Ti-15Mo specimens were subjected to alkali-hydrogen peroxide and subsequent heat treatment to produce a nanoporous titanate gel layer with anatase phase. The surface morphology of the untreated, alkali-hydrogen peroxide treated and alkali-hydrogen peroxide heat treated specimens before and after 7 days of immersion in simulated body fluid was characterized using X-ray Diffractometer (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The formation of nanoporous titanate gel layer and the growth of apatite layer over the surface modified specimens after 7 days of immersion in simulated body fluid were confirmed. Further, the electrochemical corrosion behavior of all the specimens was examined using potentiodynamic polarization and electrochemical impedance spectroscopic techniques.     

Determination of the number of containers,production kanbans and withdrawal kanbans; and scheduling in kanban flowshops - Part 1

In the first part of this paper, we consider a kanban-controlled flowshop and present recursive equations for time-tabling of containers in a given sequence. The flowshop is characterized by the following: a production batch of a part-type (or job) divided into kanban lots or containers; production kanbans to control the loading of containers on machines or workstations; withdrawal kanbans to regulate the movement of containers between two consecutive buffer storages; periodic material handling of containers; dual blocking mechanisms operative on workstations and material handling; and sequence-dependent set-up times of containers. Considering different types of problems, recursive equations have been developed for time-tabling of containers in a given sequence.     

CORROSION INHIBITION OF CARBON STEEL IN LOW CHLORIDE MEDIA BY AN AQUEOUS EXTRACT OF HIBISCUS ROSA-SINENSIS LINN

The inhibition efficiency (IE) of an aqueous extract of white flower, namely, Hibiscus rosa-sinensis Linn., in controlling corrosion of carbon steel immersed in an aqueous solution containing 60 ppm of Cl^-has been evaluated by the mass loss method. The flower extract (FE) shows good IE. In the presence of Zn²⁺, excellent IE is shown by the flower extract. A synergistic effect exists between the flower extract and Zn²⁺. The mechanistic aspects of corrosion inhibition have been investigated by polarization study and AC impedance spectra. Polarization study reveals that the formulation consisting of flower extract and Zn²⁺ functions as a mixed inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. The active principle in the flower extract is quercetin-3-O-glucoside. This has been confirmed by UV-visible absorption spectra. The protective film formed on the metal surface has been analyzed by FT-IR and AFM spectra. It is found that the protective film consists of Fe²⁺-quercetin-3-O-glucoside complex and Zn(OH)₂.     

Confocal ultrafast pump-probe spectroscopy: a new technique to explore nanoscale composites

This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe technique, able to study the photophysics of different structured materials with nanoscale resolution. This tool offers many advantages over standard stationary microscopy techniques because it directly interrogates excited state dynamics in molecules, providing access to both radiative and non-radiative deactivation processes at a local scale. In this paper we present a few different examples of its application to organic semiconductor systems. The first two are focussed on the study of the photophysics of phase-separated polymer blends: (i) a blue-emitting polyfluorene (PFO) in an inert matrix of PMMA and (ii) an electron donor polythiophene (P3HT) mixed with an electron acceptor fullerene derivative (PCBM). The experimental results on these samples demonstrate the capability of the technique to unveil peculiar interfacial dynamics at the border region between phase-segregated domains, which would be otherwise averaged out using conventional pump-probe spectroscopy. The third example is the study of the photophysics of isolated mesoscopic crystals of the PCBM molecule. Our ultrafast microscope could evidence the presence of two distinctive regions within the crystals. In particular, we could pinpoint for the first time areas within the crystals showing photobleaching/stimulated emission signals from a charge-transfer state.     

Influence of Si nanoparticles on the electrochemical behavior of organic coatings on carbon steel in chloride environment

Scanning electrochemical microscopy (SECM) is an excellent technique to detect electrochemical processes with high spatial resolution. In this work, the effect of silicon (Si) nanoparticles on the corrosion protection performance of epoxy-coated steel was examined by electrochemical impedance spectroscopy (EIS) and SECM analysis. The EIS was performed in continuous immersion in 0.1?M NaCl_(aq) solution. The addition of Si nanoparticles increased the coating film resistance (R _f) and the charge transfer resistance (R _ct) of coated steel. SECM mapping and line scan analysis was performed in order to estimate the coating performance with Si nanoparticles in 0.1?M NaCl_(aq) solution. SECM results indicated that the tip current at ?0.70?V was decreased by the addition of Si nanoparticles in epoxy film. These results suggested that the dissolved oxygen (DO) was consumed by anodic dissolution of Si nanoparticles. Surface analysis showed that the Si was enriched at the scratched region of the coated steel after a corrosion test. From these results, Si was dissolved as Si ⁿ⁺ and transferred to the scratched area, and then consumed the DO in the solution. Thus, the anodic dissolution of Fe at the scratched area was suppressed by the Si nanoparticles, which implies the sacrificial effect of Si from the coating against the steel corrosion. Hence, it was concluded that the Si nanoparticles had a beneficial effect on enhancing the corrosion resistance of the coated steel.     

Collective cell guidance by cooperative intercellular forces

Cells comprising a tissue migrate as part of a collective. How collective processes are coordinated over large multi-cellular assemblies has remained unclear, however, because mechanical stresses exerted at cell-cell junctions have not been accessible experimentally. We report here maps of these stresses within and between cells comprising a monolayer. Within the cell sheet there arise unanticipated fluctuations of mechanical stress that are severe, emerge spontaneously, and ripple across the monolayer. Within that stress landscape, local cellular migrations follow local orientations of maximal principal stress. Migrations of both endothelial and epithelial monolayers conform to this behaviour, as do breast cancer cell lines before but not after the epithelial-mesenchymal transition. Collective migration in these diverse systems is seen to be governed by a simple but unifying physiological principle: neighbouring cells join forces to transmit appreciable normal stress across the cell-cell junction, but migrate along orientations of minimal intercellular shear stress.     

Synthesis of hydrophilic superparamagnetic magnetite nanoparticles via thermal decomposition of Fe(acac), in 80 vol% TREG + 20 vol% TREM

In this paper, we report single step synthesis of hydrophilic superparamagnetic magnetite nanoparticles by thermolysis of Fe(acac)3 and their characterization of the properties relevant to biomedical applications like hyperthermia and magnetic resonance imaging (MRI). Size and morphology of the particles were determined by Transmission electron microscopy (TEM) while phase purity and structure of the particles were identified by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Magnetic properties were evaluated using vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The as prepared nanoparticles were found to be superparamagnetic with the blocking temperature of 136 K and were easily suspendable in water. Cytotoxicity studies on human cervical (SiHa), mouse melanoma (B16F10) and mouse primary fibroblast cells demonstrated that up to a dose of 0.1 mg/ml, the magnetite nanoparticles were nontoxic to the cells. To evaluate the feasibility of their uses in hyperthermia and MRI applications, specific absorption rate (SAR) and spin-spin relaxation time (T2) were measured respectively. SAR has been calculated to be above 80 Watt/g for samples with the iron concentration of 5-20 mg/ml at 10 kA/m AC magnetic field and 425 kHz frequency. r2 relaxivity value was measured as 358.4 mM(-1)S(-1) which is almost double as compared to that of the Resovist, a commercially available MRI contrast agent. Thus the as-prepared magnetite nanoparticles may be used for hyperthermia and MRI applications due to their promising SAR and r2 values.