Block Copolymer Nanostructures and Their Applications: A Review

Block copolymer nanostructures are smart, intelligent, and environment sensitive nanostructures designed to respond in a controlled manner to an external stimulus. Block copolymer nanostructures are being extensively utilized in pharmaceutical field, nanotechnology, and inforensics. Upon micellization, the hydrophobic core of block copolymer nanostructures region serves as a reservoir for hydrophobic medication, which can be loaded by chemical, physical, or electrostatic means. DNA combined with synthetic block copolymer nanostructure enhances the chemical and biological behaviors of biomacromolecule and at the same time completely suppress undesirable properties. Novel Nanoelectromechanical Systems/Microelectromechanical Systems (NEMS/MEMS) devices are being realized using block copolymer nanostructures and DNA combined with inorganic material nanoparticles and small organic moieties.     

Synthesis of augmented biofuel processes using solar energy

A method for synthesizing augmented biofuel processes, which improve biomass carbon conversion to liquid fuel (η_carbon) using supplemental solar energy as heat, H₂, and electricity is presented. For a target η_carbon, our method identifies augmented processes requiring the least solar energy input. A nonconvex mixed integer nonlinear programming model allowing for simultaneous mass, heat, and power integration, is built over a process superstructure and solved using global optimization tools. As a case study, biomass thermochemical conversion via gasification/Fischer–Tropsch synthesis and fast‐hydropyrolysis/hydrodeoxygenation (HDO) is considered. The optimal process configurations can be categorized either as standalone (η_carbon ≤ 54%), augmented using solar heat (54% ≤ η_carbon ≤ 74%), or augmented using solar heat and H₂ (74 ≤ η_carbon ≤ 95%). Importantly, the process H₂ consumption is found to be close to the derived theoretical minimum values. To accommodate for the intermittency of solar heat/H₂, we suggest processes that can operate at low and high η_carbon. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2533–2545, 2014     

A novel approach to combine features for salient object detection using constrained particle swarm optimization

Despite significant amount of research works, the best available visual attention models still lag far behind human performance in predicting salient object. In this paper, we present a novel approach to detect a salient object which involves two phases. In the first phase, three features such as multi-scale contrast, center-surround histogram and color spatial distribution are obtained as described in Liu et al. model. Constrained Particle Swarm Optimization is used in the second phase to determine an optimal weight vector to combine these features to obtain saliency map to distinguish a salient object from the image background. To achieve this, we defined a simple fitness function which highlights a salient object region with well-defined boundary and effectively suppresses the background regions in an image. The performance is evaluated both qualitatively and quantitatively on a publicly available dataset. Experimental results demonstrate that the proposed model outperforms existing state-of-the-art methods in terms of precision, recall, F -measure and area under curve.     

Parametric Understanding of Electro-Chemical Buffing (ECB) Using Current-Voltage Characterization

In recent times, the electro-chemical buffing (ECB) process is being used as a substitute for electro-polishing as it gives a clean and hygienic surface with nano-scale surface finish. This environmentally friendly process finds applications in polishing of ultra-high vacuum systems, niobium SRF cavity and high-purity components. Despite being known over a long time, the process mechanism involving passive layers formation and consequent nano-metric finish generation have not been discussed adequately in the open domain. This article, therefore, focuses on the characterization of ECB process by capturing current-voltage (I-V) relationship as a function of processing parameters. The parametric settings that give the largest passive zone as obtained from the I-V relationship, have been explored in detail using response surface methodology-based experimentation. The I-V characterization shows that the width of passive or constant current region is the largest for 10% concentration of electrolyte, 100 μm inter-electrode gap, 25 LPH flow of electrolyte and 900 rpm of buff-head. A higher surface finish improvement and minimum surface roughness of 30.66 nm is achieved at comparatively moderate concentration and high flow rate of electrolyte, smaller inter-electrode gap and high rotational speed of the buff-head in the ECB process.     

Editorial

AT&T Bell Laboratories     

Spindle cell carcinoma of right lower alveolus. A case report

A case report of spindle cell carcinoma of the right mandibular alveolus is reported, which clinically mimicked a squamous cell carcinoma. Careful histological interpretation is necessary for successful treatment of such tumors. The use of radiation therapy after radical neck dissection is also stressed upon.     

Interdomain interactions between the hydrophilic domains of the mannitol transporter of Escherichia coli in the unphosphorylated and phosphorylated states

Interdomain interactions in the mannitol-specific enzyme II of the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli play a key role in the mechanism of mannitol transport across the membrane [Boer et al. (1995) Biochemistry 34, 3239-3247; Loikema et al. (1991) Biochemistry 30, 6716-6721]. In this study, we focus on the interaction between the hydrophilic A and B domains and try to determine those as a function of the phosphorylation state of the enzyme. To this end, unfolding studies on the subcloned domains IIAmtl and IIBmtl, as well as on the binary combination IIBAmtl, were performed, both in the unphosphorylated and in the phosphorylated states, using GuHCl and heat as the denaturant. It is shown that IIAmtl and IIBmtl, as well as P-IIAmtl and P-IIBmtl, unfold according to a two-state mechanism but that IIBAmtl and P2-IIBAmtl do not exhibit such behavior. Two transitions are observed instead, indicating a lack of strong positive cooperative interactions. DSC studies of the unphosphorylated proteins showed a destabilization of the B domain in IIBAmtl with respect to the free IIBmtl as indicated by a lowereing of the melting temperature and a lower enthalpy of unfolding. Furthermore, it is shown that phosphorylation has a destablilizing effect on both IIAmtl and IIBAmtl but not on IIBmtl. Possible explanations for this behavior and the biological relevance of the destabilizing forces in IIBAmtl are discussed.     

A Novel Fullerene Hydroxamic Acid for the Liquid-Liquid Extraction, Separation, Preconcentration, and Spectrophotometric and ICP-AES Determination of Vanadium

A new reagent N-phenyl-(1,2 methanofullerene C₆₀)61-formohydroxamic acid (PMFFA) is reported for extraction and trace determination of vanadium(V) in nutritional and biological substrates. The extraction mechanism of vanadium from 6 M HCl media is investigated. The influence of PMFFA, diverse ions, and temperature on the distribution constant of vanadium examined. The over all stability constant (log β₂K_e) and extraction constant (K_ex) are 20.89 ± 0.02 and 8.0 ± 0.02 × 10^-15, respectively in chloroform. The thermodynamics parameters are calculated and kinetics of vanadium transport is discussed. The system obeys Beer's law in the range of 3.2-64.0 ng mL^-1 of vanadium(V). The molar absorptivity is 7.96 × 10⁵ L mol^-1 cm^-1, at 510 nm. The PMFFA-vanadium(V) complex chloroform extract in chloroform was directly inserted into plasma for ICP-AES measurement, which increases the sensitivity by 50 folds and obey Beer's law in the range of 50-1200 pg mL^-1 of vanadium(V). The method is applied for determination vanadium in real standard samples, sea water, and environmental samples.     

Specific ventilation distribution in microgravity

We studied the contribution of inter- and intraregional inhomogeneities of specific ventilation (delta V/Vo) from the rebreathing inert gas trace in microgravity and on Earth. The rebreathing tests were carried out by four astronauts before, during, and after the 10-day Spacelab D-2 mission. Starting from functional residual capacity, the rebreathing maneuver consisted of eight reinspirations from a bag filled with 1.8-2.2 liters of test gas mixtures containing approximately 5% argon. The rate of argon equilibration in the rebreathing bag, termed RBeq, was quantified by determining the logarithm of the actual minus the equilibrated argon concentrations normalized to the inspired minus the equilibrated argon concentrations. A compartmental model of the lung (S. Verbanck and M. Paiva. J. Appl. Physiol. 76: 445-454, 1994) was used to validate the method for determining RBeq and to simulate the influence of intra- and interregional delta V/Vo inhomogeneities on the RBeq curve. The comparison between the experimental Earth-based and microgravity RBeq curves and model simulations shows that gravity-independent delta V/Vo inhomogeneity is at least as large as gravity-dependent delta V/Vo inhomogeneity.