Electrochemical quantification of d-glucose during the production of bioethanol from thermo-mechanically pre-treated wheat straw.

Mechanical pre-treatment (disc refining) of wheat straw, at both atmospheric and elevated pressure, is shown to be an efficient process to access fermentable monosaccharides, with the potential to integrate within the infrastructure of existing first-generation bioethanol plants. The mild, enzymatic degradation of this sustainable lignocellulosic biomass affords ca. 0.10-0.13 g/g (dry weight) of d-glucose quantifiable voltammetrically in real time, over a two hundred-fold range in experimental laboratory scales (25 mL to 5.0 L), with pressure disc refining of the wheat straw enabling almost twice the amount of d-glucose to be generated during the hydrolysis stage than experiments using atmospheric refining (0.06-0.09 g/g dry weight). Fermentation of the resulting hydrolysate affords 0.08-0.10 g/g (dry weight) of ethanol over similar scales, with ethanol productivity at ca. 37 mg/(L h). These results demonstrate that minimal cellulose decomposition occurs during pressure refining of wheat straw, in contrast to hemicellulose, and suggest that the development of green, mechanochemical processes for the scalable and cost-effective manufacture of second-generation bioethanol requires improved cellulose decomposition.

Regular Solution Theory for Polymer Permeation Transients: A Toolkit for Understanding Experimental Waveshapes.

The accurate measurement of permeation is important at the product design stage for a variety of industries as diverse as conveyance methods for oil and gas produced fluids, such as mixtures of carbon dioxide, methane, hydrogen sulfide, water, and hydrocarbons, and in polymer-lined, unbonded flexible risers and flow lines through connectors and valves, hydrogen and methane gas carrying domestic lines, hydrogen storage tanks, sulfur hexafluoride circuit breakers for high power-carrying lines, oxygen through display technology, and drug delivery. It would also be appropriate to monitor the permeation rate through the polymer, composite, and elastomeric layers during the in-service times where applications allow. In the future, any alteration in the short term and long-term transport rates could be analyzed in terms of an initial alteration or degradation of the polymeric materials and, in some cases, metallic components. Crucially, such measurements would serve as an early warning system of any change in a polymeric material that could result in the loss of function of the fluid of a gas containing barrier material. Most experimental determinations are made through recording flux transients (varying flux) through permeation cells in which a polymer membrane or film separates a donor compartment (usually an infinite supply) and an acceptor compartment and in which membrane transport is considered to be slow. Treatment of the resulting experimental data is usually, but not always, undertaken through comparison with a steady-state model based on Fickian diffusion through the membrane, so as to extract the membrane permeability, the diffusion coefficient of the permeant, and the solubility of the permeant in the membrane phase. However, in spite of these measurements being undertaken routinely using closed cell manometric or continuous flow methods, there is a lack of literature in which experimental flux transients are provided, and in several cases, it is clear that the experimental data do not conform to the expected model of slow, Fickian diffusion through the membrane, even though experiments are performed at temperatures much higher than the glass transition temperature of the polymer membrane. In this paper, we first re-examine the classical model for an infinite source and extend it to account for (1) molecular interactions between membrane and permeant, using regular solution theory, (2) slow transport in the acceptor phase, and (3) slow kinetics across the membrane|acceptor interface. We demonstrate that all three aspects can cause permeation flux transients to exhibit unusual, nonclassical waveshapes, which have nevertheless been experimentally realized without rationalization. This enables the development of an algorithmic toolkit for the interpretation of permeation flux transients, so as to provide reliable and accurate data analysis for experimentalists.

Febrile illness in a young traveler: dengue fever and its complications.

BACKGROUND: Dengue fever, a tropical disease once confined mostly to endemic areas in developing countries, is becoming more prevalent. Globalization has led to an increased incidence of the virus both in foreign travelers returning home and local outbreaks in traditionally nonendemic areas, such as the southern United States and southern Europe. Advances in diagnostic tests, therapies, and vaccines for dengue virus have been limited, but research is ongoing. OBJECTIVES: To review the current literature regarding the diagnosis and management of dengue fever. CASE REPORT: This case report describes a young woman returning from Central America with many of the common signs and symptoms who was misdiagnosed both abroad and at home. We explore the epidemiology, disease course, complications, and treatment of dengue fever. CONCLUSION: Emergency physicians should consider dengue fever in patients with acute febrile illnesses, especially among those with recent travel.

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths.

A product-scalable, catalytically mediated flow system has been developed to perform Suzuki-Miyaura reactions under a microwave heating regime, in which the volumetric throughput of a Pd-supported silica monolith can be used to increase the quantity of the product without changing the optimal operating conditions. Two silica monoliths (both 3 cm long), with comparable pore diameters and surface areas, were fabricated with diameters of 3.2 and 6.4 mm to give volumetric capacities of 0.205 and 0.790 mL, respectively. The two monoliths were functionalized with a loading of 4.5 wt % Pd and then sealed in heat-shrinkable Teflon(®) tubing to form a monolithic flow reactor. The Pd-supported silica monolith flow reactor was then placed into the microwave cavity and connected to an HPLC pump and a backpressure regulator to minimize the formation of gas bubbles. The flow rate and microwave power were varied to optimize the reactant contact time and temperature, respectively. Under optimal reaction conditions the quantity of product could be increased from 31 mg per hour to 340 mg per hour simply by changing the volumetric capacity of the monolith.

Electrochemically Induced Mesomorphism Switching in a Chlorpromazine Hydrochloride Lyotropic Liquid Crystal.

The discovery of electrochemical switching of the Lα phase of chlorpromazine hydrochloride in water is reported. The phase is characterized using polarizing microscopy, X-ray scattering, rheological measurements, and microelectrode voltammetry. Fast, heterogeneous oxidation of the lyotropic liquid crystal is shown to cause a phase change resulting from the disordering of the structural order in a stepwise process. The underlying molecular dynamics is considered to be a cooperative effect of both increasing electrostatic interactions and an unfolding of the monomers from "butterfly"-shaped in the reduced form to planar in the oxidized form.

Solution-processable and photopolymerisable TiO2 nanorods as dielectric layers for thin film transistors.

We report the fabrication of a solution-processed n-type Thin Film Transistor (TFT) with current on/off ratios of 104, a turn-on voltage (V ON) of 1.2 V and a threshold voltage (V T) of 6.2 V. The TFT incorporates an insoluble and intractable dielectric layer (k = 7-9) prepared in situ from solution-processed and then photopolymerised ligand-stabilised, inorganic/organic TiO2 nanorods. A solution processed zinc oxide (ZnO) layer acts as the semiconductor. The new surface-modified TiO2 nanorods were synthesised using a ligand replacement process with a monolayer coating of photopolymerisable 10-undecynylphosphonic acid (10UCYPA) to render them both soluble in common organic solvents and be photopolymerisable using UV-illumination after having been deposited on substrate surfaces from solution and drying.

Grazing incidence X-ray diffraction of a photoaligned nematic semiconductor.

Grazing incidence X-ray diffraction is used to find the thin film morphology of an extended molecule with an irregular alternating fluorene-thiophene structure, which is used to obtain linearly polarized electroluminescence and the photovoltaic effect. The material has a room temperature nematic glassy phase and is uniaxially aligned in the plane of the film using photoalignment techniques. Two distinct intermolecular separations of 0.45 and 1.5 nm are identified showing that the molecules are lamellar. The lamellae stack with only local order and the two short axes of the lamellae have no preferred orientation at the surface or bulk of the film. Neighboring molecules show a wide range of longitudinal displacements along the axis of the director, as expected for a nematic liquid crystal with no positional order. There is, however, a dominant feature corresponding to a longitudinal offset of 0.51 nm. Unlike some other fluorene-containing semiconductors where microphase separation of the side chains inhibits close packing of neighboring molecules, the lamellar structure and 0.45 intermolecular spacing found here allows pi-pi intermolecular interactions for efficient carrier transport. We obtain a room temperature hole mobility up to 3.4 x 10-3 cm2 V-1 s-1 using a time-of-flight technique.

Lyotropic 'hairy' TiO2 nanorods.

We report the synthesis of the first stable, solution-processable and photocrosslinkable hybrid organic/inorganic titanium dioxide nanorods as 'hairy rods' coated with phosphonate ligands with photoreactive coumarin groups located in a terminal position. The relationships between the chemical structure of the diethyl-ω-[(7-oxycoumaryl)-n-alkyl]phosphonate ligands on the ligand exchange rate (LER) and the solubility of the resultant ligand-stabilized titanium dioxide nanorods in organic solvents are elucidated. These TiO2 nanorods, with an organic ligand coating, are short enough (aspect ratio = 5-8) to be dissolved in chlorobenzene at high concentrations, but long enough to form lyotropic nematic liquid crystals. These colloidal solutions are used to deposit a thin, uniform layer of hybrid organic/inorganic TiO2 nanorods with their long axes in the plane of a flat, smooth substrate through a self-organization process. Standard photolithographic patterning creates an insoluble dielectric layer of the desired thickness, smoothness and uniformity and with a dielectric constant of sufficient magnitude, k = 8, suitable for the fabrication of multilayer, plastic electronic devices using solution-based fabrication techniques, such as ink-jet printing, used in roll-to-roll manufacturing.

Dynamics of the size distribution of CdTe quantum dot ensembles during growth in liquid and crystalline phases.

We recently reported that the growth rate of colloidal CdTe nanoparticles decreases by orders of magnitude when the particles undergo a phase transition from liquid to crystal. The dynamics of nanoparticle growth are dominated by this factor rather than the size dependence of the chemical potential. Herein we discuss how the phase transition affects the size distribution and photoluminescence quantum efficiency of the nanoparticles. We suggest that the absorption linewidth is a better monitor of size distribution than the photoluminescence linewidth because the photoluminescence quantum efficiency, which affects the latter via energy transfer, varies substantially with reaction time. We find that the size distribution broadens in the early stages of growth possibly because of inhomogeneities in the phase transition radius or because particles nucleated at later times coalesce with nanocrystals. The quantum efficiency is enhanced when tellurium is depleted in the reaction solution, giving a cadmium-enriched surface. Batches with high initial tellurium and cadmium concentrations show a substantial amount of delayed nucleation, lower quantum efficiency and some anisotropic growth.

Polymer network hole transport layers based on photochemically cross-linkable N'N'-diallyl amide tri-N-substituted triazatruxene monomers.

Novel phtotpolymerisable hole-transport layers based on novel triazatruxenes incorporating six non-conjugated dienes as photo cross-linkable end-groups attached to flexible, aliphatic spacers have been synthesised using simple one-step substitution reactions. Hole-only test devices, fabricated using a combination of solution-deposition, spin-coating and initiator-free photochemical cross-linking of these photopolymerisable triazatruxenes, exhibit almost identical current density vs. voltage profiles before and after cross-linking, and as such, represent a promising new class of hole-transport layer for plastic electronic devices.

LRSim: A Linked-Reads Simulator Generating Insights for Better Genome Partitioning.

Linked-read sequencing, using highly-multiplexed genome partitioning and barcoding, can span hundreds of kilobases to improve de novo assembly, haplotype phasing, and other applications. Based on our analysis of 14 datasets, we introduce LRSim that simulates linked-reads by emulating the library preparation and sequencing process with fine control over variants, linked-read characteristics, and the short-read profile. We conclude from the phasing and assembly of multiple datasets, recommendations on coverage, fragment length, and partitioning when sequencing genomes of different sizes and complexities. These optimizations improve results by orders of magnitude, and enable the development of novel methods. LRSim is available at https://github.com/aquaskyline/LRSIM.

Silicon diimide gel as an efficient stationary phase in thin layer chromatography for acid-sensitive organic compounds.

We report the use of mesoporous silicon diimide gel as a basic stationary phase in thin layer chromatography for the characterisation and purification of acid-sensitive compounds. The gel is prepared by a simple sol-gel process and exhibits a large specific surface area, almost monodisperse pores and basic properties due to free-hanging amine groups.

Reversible optical switching memristors with tunable STDP synaptic plasticity: a route to hierarchical control in artificial intelligent systems.

Optical control of memristors opens the route to new applications in optoelectronic switching and neuromorphic computing. Motivated by the need for reversible and latched optical switching we report on the development of a memristor with electronic properties tunable and switchable by wavelength and polarization specific light. The device consists of an optically active azobenzene polymer, poly(disperse red 1 acrylate), overlaying a forest of vertically aligned ZnO nanorods. Illumination induces trans-cis isomerization of the azobenzene molecules, which expands or contracts the polymer layer and alters the resistance of the off/on states, their ratio and retention time. The reversible optical effect enables dynamic control of a memristor's learning properties including control of synaptic potentiation and depression, optical switching between short-term and long-term memory and optical modulation of the synaptic efficacy via spike timing dependent plasticity. The work opens the route to the dynamic patterning of memristor networks both spatially and temporally by light, thus allowing the development of new optically reconfigurable neural networks and adaptive electronic circuits.

Pancreatic ß cell identity requires continual repression of non-ß cell programs.

Loss of ß cell identity, the presence of polyhormonal cells, and reprogramming are emerging as important features of ß cell dysfunction in patients with type 1 and type 2 diabetes. In this study, we have demonstrated that the transcription factor NKX2.2 is essential for the active maintenance of adult ß cell identity as well as function. Deletion of Nkx2.2 in ß cells caused rapid onset of a diabetic phenotype in mice that was attributed to loss of insulin and downregulation of many ß cell functional genes. Concomitantly, NKX2.2-deficient murine ß cells acquired non-ß cell endocrine features, resulting in populations of completely reprogrammed cells and bihormonal cells that displayed hybrid endocrine cell morphological characteristics. Molecular analysis in mouse and human islets revealed that NKX2.2 is a conserved master regulatory protein that controls the acquisition and maintenance of a functional, monohormonal ß cell identity by directly activating critical ß cell genes and actively repressing genes that specify the alternative islet endocrine cell lineages. This study demonstrates the highly volatile nature of the ß cell, indicating that acquiring and sustaining ß cell identity and function requires not only active maintaining of the expression of genes involved in ß cell function, but also continual repression of closely related endocrine gene programs.

Nfib Regulates Transcriptional Networks That Control the Development of Prostatic Hyperplasia.

A functional complex consisting of androgen receptor (AR) and forkhead box A1 (FOXA1) proteins supports prostatic development, differentiation, and disease. In addition, the interaction of FOXA1 with cofactors such as nuclear factor I (NFI) family members modulates AR target gene expression. However, the global role of specific NFI family members has yet to be described in the prostate. In these studies, chromatin immunoprecipitation followed by DNA sequencing in androgen-dependent LNCaP prostate cancer cells demonstrated that 64.3% of NFIB binding sites are associated with AR and FOXA1 binding sites. Interrogation of published data revealed that genes associated with NFIB binding sites are predominantly induced after dihydrotestosterone treatment of LNCaP cells, whereas NFIB knockdown studies demonstrated that loss of NFIB drives increased AR expression and superinduction of a subset of AR target genes. Notably, genes bound by NFIB only are associated with cell division and cell cycle. To define the role of NFIB in vivo, mouse Nfib knockout prostatic tissue was rescued via renal capsule engraftment. Loss of Nfib expression resulted in prostatic hyperplasia, which did not resolve in response to castration, and an expansion of an intermediate cell population in a small subset of grafts. In human benign prostatic hyperplasia, luminal NFIB loss correlated with more severe disease. Finally, some areas of intermediate cell expansion were also associated with NFIB loss. Taken together, these results show a fundamental role for NFIB as a coregulator of AR action in the prostate and in controlling prostatic hyperplasia.

Charge-transport in crystalline organic semiconductors with liquid crystalline order.

We report the design and synthesis of a liquid crystalline material exhibiting highly ordered smectic phases and high charge carrier-mobility; by a process known as "paramorphosis" highly ordered smectic phases can be transferred to the amorphous crystalline state on crystallisation without the formation of significant crystal grain boundaries and deep traps.

General method of preparation of mesoporous M/Si3N4 nano-composites via a non-aqueous sol-gel route.

We report a general method for the preparation of transition-metal silicon nitride nanocomposites; for example, mesoporous Pd-Si3N4 nanocomposite materials with high surface area were prepared by pyrolysis of a silicon palladium imide-chloride complex which was synthesized by reaction of silicon diimide gel with palladium chloride. These porous nanocomposites catalyse organic reactions.

Stokes parameter studies of spontaneous emission from chiral nematic liquid crystals as a one-dimensional photonic stopband crystal: experiment and theory.

The helical structure of uniformly aligned chiral nematic liquid crystals results in a photonic stopband for only one sense of circular polarization. The spectroscopic Stokes polarimeter is used to analyze spontaneous emission in the stopband. Highly polarized photoluminescence is found and the polarization properties vary with the excitation wavelength. Spontaneous emission is enhanced at the stopband edge and this Purcell effect is greater on excitation at wavelengths where the absorption coefficient is low. This is interpreted as greater overlap between the excited molecules and the electrical modal field of the resonant modes at the stopband edge. Photoluminescence detected from the excitation face of the liquid crystal cell is less polarized because of photon tunneling. Fermi's golden rule in conjunction with Stokes vectors is used to model the polarization of emission taking multiple reflections at the interfaces of the cell into account. The discrepancy between the experiment and the theoretical model is interpreted as direct experimental evidence that virtual photons, which originate from zero point fluctuations of quantum space, are randomly polarized.

Studies on the sulfation of cellulose α-lipoate and ability of the sulfated product to stabilize colloidal suspensions of gold nanoparticles.

A versatile method for the synthesis of cellulose α-lipoate with a low degree of substitution (DS) has been developed using N,N-dimethylacetamide (DMA)/LiCl as a solvent and N,N'-carbonyldiimidazole (CDI) as an esterification reagent. The cellulose α-lipoate with DS of α-lipoate groups of 0.26 was converted with sulfur trioxide-pyridine complex in dimethyl sulfoxide (DMSO) as solvent. The sulfation is accompanied by an unexpected partial oxidation of the disulfide moiety leading to the formation of the corresponding stereoisomers of S-oxides. The resulting mixture of water-soluble cellulose α- and ß-lipoate sulfate possesses a DS of sulfuric acid half ester groups of 1.78. This cellulose-α/ß-lipoate sulfate derivative can be used as an effective stabilizer and solubilizer for the formation of colloidal suspensions of gold nanoparticles formed in situ in aqueous solution.

Green synthesis of highly concentrated aqueous colloidal solutions of large starch-stabilised silver nanoplatelets.

A simple, environmentally friendly and cost-effective method has been developed to prepare a range of aqueous silver colloidal solutions, using ascorbic acid as a reducing agent, water-soluble starch as a combined crystallising, stabilising and solubilising agent, and water as the solvent. The diameter of silver nanoplatelets increases with higher concentrations of AgNO3 and starch. The silver nanoparticles are also more uniform in shape the greater the diameter of the nanoparticles. Colloidal solutions with a very high concentration of large, flat, hexagonal silver nanoplatelets (~230 nm in breadth) have been used to deposit and fix an antibacterial coating of these large starch-stabilised silver nanoplates on commercial cotton fibres, using a simple dip-coating process using water as the solvent, in order to study the dependence of the antibacterial properties of these nanoplatelets on their size.