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Therapeutic efficiency of amphiphilic methotrexate-camptothecin (MTX-CPT) prodrug compared to free drug mixture (MTX/CPT) has been investigated using all-atom molecular dynamics simulation and first principles density functional theory calculations. This comparison revealed that MTX-CPT prodrug tends to form spherical self-assembled nanoparticle (NP), while free MTX/CPT mixture forms rod-shape NP. These observations are attributed to a structural defect in the MTX-CPT prodrug and solvation free energies of MTX, CPT and MTX-CPT molecules. The results provided evidence that noncovalent interactions (NCIs) among the pharmaceutical drugs play a very important role in anticancer agents aggregation process, leading to enhanced stability of the self-assembled NPs. It is found that the stability of MTX-CPT self-assembled NP is greater than the MTX/CPT NP due to the synergistic effect of hydrogen bonding between monomers and solvent (water). Moreover, the noncatalyzed as well as catalyzed hydrolysis reactions of MTX-CPT prodrug are theoretically studied at the PCM(water)//M06-2X/6-31G(d,p) computational level to shed additional light on the role of acidic condition in tumor tissues. We found that the ester hydrolysis in mild acidic solutions is a concerted reaction. In an agreement between theory and experiment, we also confirmed that the activation energies of the catalyzed-hydrolysis steps are much lower than the activation energies of the corresponding steps in the noncatalyzed reaction. Thus, the MTX-CPT prodrug reveals very promising properties as a pH-controlled drug delivery system.

The difference in combustion performance between brown coal and black coal blended with Eucalyptus woodchip and woodchar in varying blending ratios were examined in the air and oxy firing conditions. On top of the experimental investigation using a drop tube furnace (DTF), a computational fluid dynamics (CFD) model was further developed to interpret these results, validated using the experimental data. The CFD model incorporates a comprehensive reaction for devolatilisation reaction to predict the gas release utilising predictions based on chemical percolation devolatilisation (CPD) model. The heterogeneous reactions are defined based on the intrinsic reaction model that accounts for the influence of char properties in chemical and pore diffusion reactions using a user-defined function (UDF). Moreover, the C–CO2 gasification reaction rate which is critical in an oxy-firing mode was further studied using the CFD tool to determine how the role of gasification varied for various fuel blends. Based on carbon burnout and average particle temperature profiles, the blending of woodchips is highly beneficial to the overall combustion performance in particular for low reactive black coal while its effect on brown coal is marginal. Woodchar and black coal are comparable with similar temperature plots and relatively constant burnout but it behaves relatively inert with a highly reactive brown coal. During oxy firing, increasing the woodchip content enhanced the effect of C–CO2 gasification due to its extremely large pre-exponential factor for the CO2 gasification reactivity which explains the improved burnout. The blending of woodchar caused a gradual reduction in the gasification extent for both coals explained by the low heating rates under which woodchar was pyrolysed and also due to the decrease in the peak particle temperature. However, the observed gasification was found to be less than the expected value based on the linear addition of the two single fuels for both biomass blends.

The “all in one” environmentally friendly sphingosine kinase inhibitor (SphKI) molecule could combine the advantages of various organic functional groups, and ambiphilic and amphipathic nature together for effective carbon dioxide (CO2) capture. The CO2 molecule interacts with various functional molecules including aromatic and multi-heteroatom (such as nitrogen and oxygen) systems through both physical and chemical absorption. In this study, the ability of SphKI with multiple reaction centers to bind CO2 is investigated using symmetry-adapted perturbation theory and a non-covalent interaction approach. The combination of these two analyses allowed us to explore the nature and strength of the SphKI⋯CO2 interactions. We found that the variety of functional groups in SphKI including guanidine, oxadiazole, phenyl, and alkyl groups allowed it to act as both an electrophile and a nucleophile (ambiphilic nature) for the CO2 physisorption. But on the other hand, the chemisorption of CO2 by SphKI only proceeded through the guanidine group in the polar head (hydrophilic) region. These results revealed that the interaction energy values are divided into physical interactions with a binding energy in the range of ∼2–32 kJ mol−1, which are mainly dominated by both electrostatic and dispersion contributions, and chemical interactions (∼16–45 kJ mol−1). Also, according to the amphipathic nature of SphKIs, a simple sphingosine-based membrane is proposed and shown to be stable by molecular dynamics simulation under aqueous conditions. By considering the chemical equilibrium between CO2 and water (H2CO3 (aq)), we used the proposed membrane to evaluate the large scale CO2-capturing efficacy of SphKIs. The simulation results showed that the CO2 molecules can diffuse into the hydrophobic phase of the SphKI membrane, while the H2CO3 molecules remain in the aqueous phase.

Introduction Mutations in the HFE gene have been shown to be associated with hemochromatosis which is observed in beta-thalassemia major. In this study, we determined the HFE gene mutations (C282Y and H63D) among b-thalassemia major patients to investigate the effect of these mutations on serum Ferritin levels. Material and methods In this cross-sectional study, a total of 105 b-thalassemia subjects with a history of regular blood transfusion were selected. They divided into two distinct groups according cut off 1000 ng/ml of serum Ferritin levels. The HFE gene mutant allele detected by RFLP-PCR. Results Of 105 thalassemia patients, 29 patients (14 male and 15 female) were heterozygote for H63D mutation, and just one male was homozygote, but for C282Y mutation just one heterozygote and one homozygote was detected, and overall 31% had coexistence of b-thal and HFE gene mutations. As expected, Ferritin levels significantly differed between groups (P = 0.001). Conclusion The impact of detection of HFE mutations could prognosis the likelihood of iron overload in multi-transfused patients, and allowing early diagnosis and proper management to overcome complications of iron overload in beta-thalassemia patients.

Aspergillus clavatus is a common environmental species known to cause occupational allergic disease in grain handlers. We have recently observed azole-resistant isolates of this fungus as a cause o...

Prior washing of coal is an essential step for the minimization of ash-related slagging and fouling inside a coal-fired boiler. With regard to the coal washing process, the recyclability of the washing reagent, usually water, is critical from both cost-effective and efficiency perspectives. This paper addresses the washing kinetics of water-soluble Na+ from two different low-rank Xinjiang coals using both fresh and used/recycled water to alleviate the ash-related fouling in low-rank coal-fired boilers. Apart from once-through fresh water washing, washing using recycled water via both multicycle single-stage and three-stage countercurrent processes was studied in detail to investigate the recyclability of water. Additionally, a modified shrinking core model (SCM) was developed to reveal the Na+ removal mechanism under all washing conditions. Our experimental results showed that the Na+ removal extent decreased with the recycling of used water due to an increase in the Na+ concentration in the recycled wate...

In this paper, an efficient HCl acid recovery method from the mixture of alkaline-earth-metal chlorides waste was demonstrated via co-pyrohydrolysis in a laboratory-scale horizontal furnace in a te...

High-purity 2-D α-Fe2O3 nanosheets and MgO nanosheets have been successfully fabricated with a high extraction yield of 45 and 25 wt %, respectively, from a brown coal fly ash, an otherwise valuele...

This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na 2 O in ash from 4.32 wt% to 0.85 and 0.19 wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5 wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25 wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4 kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acid-water two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1 kg/t coal and 48.1 kg/t coal for the three-stage water washing and acid-water two-stage washing process, respectively. Both are remarkably lower than 85.0 kg-water/t black coal. In terms of the power consumption, it decreased to ~ 9.4 kWh/t coal for the three-stage water washing process and further down to 5.8 kWh/t for the acid-water washing case, which was even slightly lower than 6.3 kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing > 2150–2520 ppm Na and/or

In this paper, utilization of Victorian brown coal in a drying - pyrolysis process to make products is techno-economically assessed. The pyrolysis process is coupled with the drying and briquette making processes in order to improve the overall efficiency and quality of the products. The pyrolysis process led to the production of char, liquid oil and hydrogen – rich, non-condensable gases. A steady-state Aspen Plus simulation model was developed that provides estimated mass and energy balances for the overall system. The effect of a change in the heating mode and heating medium of the dryer on the overall energy and overall product yields was examined. Additionally, the effect of a change in the pyrolysis gas composition and coal initial moisture were studied. Results revealed that the rotary drum dryer with hot flue gas as a heating medium showed the best performance in terms of the final yield of the pyrolysis products and CO2 emission rate. In the best case scenario using hot flue gas directly in a rot...

This study investigated the feasibility of integration of concentrated solar power (CSP) to low-rank coal pyrolysis process from the economic and technical perspective. Victorian brown coal is generally used in local power plants with low efficiency and great greenhouse gas emissions. Therefore, the development of low-emission technologies for an efficient use of such vast resources is paramount. The principal objective of this process is to upgrade Victorian brown coal to alternative fuels through a solar-assisted pyrolysis process. Upon a robust design of four different scenarios for the process integration, the effects of a variety of key variables have been examined, including different types of solar collectors, heat transfer fluids (HTF) and pyrolysis temperature. The plant operation analysis showed that integrating solar tower (ST) to provide heat for both coal drying and pyrolysis within the plant can save an average of 12.8% of the annual thermal energy demand. For the optimum solar tower design, it requires a solar multiple of 2, using carbonate salts as HTF, a design point DNI of 750 W/m2 and a heat storage capacity of 8 h to maximize its total solar energy output over a year. However, from an economical perspective, the use of solar tower for both drying and pyrolysis is economically infeasible. Instead, the parabolic trough solar collectors (PTC) designed to cover the heat required for coal drying only is most economically viable. It even shows a slightly better economic performance than the conventional pyrolysis process. The parabolic trough solar assisted pyrolysis process has the potential to reach a high net present value (NPV) of $81.1 million and a short payback period of 4.9 years, relative to an NPV of $52.8 million and a payback period of 5.1 years for the conventional pyrolysis process.

Objectives: Patients with cancer experience a lot of emotional, mental, social, and spiritual crises. However, not much has been done to meet these needs. The aim of this study was to evaluate the ...

A reaction model was developed to predict kinetic parameters and competition of Mg 2 + and Ca 2 + ions during carbonation in mild conditions, i.e. ambient temperature and up to 3 atm for the CO 2 partial pressure. The experimental carbonation results at different temperatures, Mg 2 + /Ca 2 + ratios, and atmospheric pressure were used to validate and predict the kinetic parameters of individual reactions in the aqueous phase by applying genetic algorithm and reactor modeling. This model showed a good agreement with experimental results, and satisfactorily predicted the competition between Mg 2 + and Ca 2 + and the formation of magnesian calcite (Mg N Ca (1 − N) CO 3 ). In addition, a sensitivity analysis was conducted based on the validated kinetic model to maximize the precipitation rates of Mg 2 + and Ca 2 + . It was found that the final yield for magnesian calcite is the highest for the Mg 2 + /Ca 2 + molar ratio of 1, referring to an equal concentration of two cations in the leachate. This suggests the strongest synergy between both cations for their co-precipitation. The optimum ammonia amount used as a pH-swing agent was found to be equal to the amount of ammonia released from the leaching stage in a closed loop leaching-carbonation. This amount of ammonia led to ~ 100% Mg 2 + and Ca 2 + precipitation along with the highest magnesian calcite precipitation yield.

This report examined the technical and economic feasibility of four process scenarios for the mineral carbonation of Victorian brown coal fly ash. The first two design scenarios aimed to compare the performance of two leaching agents, namely, ammonium chloride (NH4Cl) and a mixture of ammonium chloride and hydrochloric acid (NH4Cl + HCl), on product yields and cost, whereas the other two scenarios were designed to recycle the leaching residue via single or multi-stage leaching steps to co-produce a carbonate precipitate and cement additive-grade by-product. Detailed designs were developed in Aspen Plus to determine the technical and economic potential of the selected process configurations and identify the concept with the lowest overall costs relative to the product yields. As has been confirmed, the overall production costs and carbon dioxide (CO2) capture cost of the evaluated process scenarios range from ∼$61 to 333 per tonne of product and from $135 to 1091 per tonne of CO2, respectively. The process scenario that used NH4Cl + HCl as the leaching reagent had a significantly larger cost and a higher carbonation conversion compared to the other scenarios. The process configuration that recycled the leaching residue resulted in the lowest cost per tonne of fly ash and the lowest CO2 capture cost among the four proposed scenarios. The largest net present value (NPV) and the internal rate of return (IRR) as well as the shortest payback period for this scenario further confirmed its highest profitability. The NPV, IRR and payback period of $49 million, 53.4% and 2.3 years, respectively, could be achieved using Victorian brown coal fly ash in this scenario. A sensitivity analysis suggests that the change in the ammonium chloride price exerts the largest effect on the production cost. A 50% increase in the ammonium chloride cost could result in the production cost increasing by 29.5%. Additionally, the selling price of the carbon precipitate product and the production cost strongly affect the financial indices. However, the production of the cement-additive by-product exerts a marginal role on the process profit. The extra income created from the cement-additive by-product is counteracted by the larger cost related to the purchase and consumption of hydrochloric acid used in the final leaching stage.

Pyrolysis process is one of the potential routes to convert waste scrap tyres into high-value resources such as liquid oil that is low in oxygen and high in valuable hydrocarbons. Although many studies have been conducted, the understanding of the fundamental science underpinning the pyrolysis of scrap tyre chip is still far from complete. This paper has examined the mild pyrolysis of scrap tyre chips at 600 °C, in an integrated manner by examining the co-effects of several key parameters including heating rate, volatile residence time, tyre chip size and non-inert gases (CO2 and/or H2O) on the quality of tars. In particular, we aimed to elucidate the influences of particle temperature discrepancy to the surrounding gas environment and reactive gas on the tar yield and properties, under the simulated fixed-bed/rotary kiln condition that is either heated directly by hot flue gas or indirectly by reactor wall. It has been confirmed that, in a simulated fixed-bed reactor with the absence of carrier gas, the particle temperature discrepancy can be correlated exponentially to the secondary cracking extent of volatiles in a temperature discrepancy range of 100 °C. Upon an increase on the temperature discrepancy by either increasing the heating rate or tyre chip size, the inherent long-chain aliphatics preferentially underwent scission, cyclisation and polymerisation, enhancing the yields for both heavy aromatics and methane – rich light gases. The use of carrier gas (i.e. hot flue gas) is beneficial in improving tar yield and aliphaticity. As a convective heating source, it heated particles slowly and also swept out volatile vapours immediately, thereby minimising the secondary reactions. For the two major components, CO2 and steam in hot flue gas, CO2 is rather inert at 600 °C, while steam is reactive enough to reduce the heavy hydrocarbons via steam reforming reaction, upon the catalytic effect of the nascent char derived from scrap tyre chips. The hydrogenation of unsaturated alkene and aromatics was also improved, and even the methanation reaction of CO on the nascent char surface, thus leading to the overwhelming dominance of CH4 in the pyrolysis gas.

Objective The aim of the present study was to provide insight into the prevalence and susceptibility profiles of Candida species isolated from the dental plaque of Iranian immunocompetent patients. As a biofilm, Candida species are responsible for several disorders common to the oral cavity including gingivitis, dental caries, periodontitis, and the less common severe systemic infections specifically in immunosuppressed individuals. Method PCR-RFLP was performed to identify yeasts isolated from the dental plaques of 40 immunocompetent patients. Moreover, antifungal susceptibility testing was performed in according to CLSI guidelines (M27-A3). Results Among 40 yeasts isolated from the dental plaques of immunocompetent patients, Candida albicans was the most common species (92.5%), followed by P. kudriavzevii (7.5%). It is the first isolation of P. kudriavzevii from dental plaques and the first evaluation of antifungal effect of the new imidazole, luliconazole and echinocandins against these samples worldwide. Luliconazole, voriconazole, amphotericin B and anidulafungin showed the best activity with the lowest geometric mean (GM) 0.03, 0.06, 0.08 and 0.09 μg/ml, respectively, followed by miconazole (0.14 μg/mL), caspofungin (0.24 μg/mL) fluconazole (0.38 μg/mL) and itraconazole (0.5 μg/mL). Conclusion The current study demonstrated luliconazole and echinocandins displayed excellent activity against all Candida isolates from dental plaques, presenting promising and potent alternative for all oral Candidiasis.

The in vitro activity of tavaborole, an FDA-approved antifungal drug, was compared to that of four antifungal agents against 170 clinical fungal isolates originating from patients with onychomycosis. Tavaborole had low activity against all isolates compared to itraconazole, terbinafine, and fluconazole, the principal choices for treatment of onychomycosis. Thus, it appears that tavaborole is not a candidate for the treatment of onychomycosis due to Candida species, Aspergillus species, and dermatophytes.

This paper attempts to develop a modified chemical percolation devolatilization (M-CPD) model that can include heat transfer, primary pyrolysis and the secondary cracking reactions of volatiles together to describe the pyrolysis of waste scrap tyre chip, as well as to examine the influence of operating conditions on the scrap tyre pyrolysis product yields. Such a study has yet to be conducted in the past, thereby leading to a large knowledge gap failing to understand the pyrolysis of the coarse feedstock appropriately. To validate the developed model, a number of operating parameters including reactor configurations, carrier gas compositions (argon and argon blended with CO2 and/or steam), scrap tyre chip size (0.5–15.0 mm), terminal pyrolysis temperature (400–800 °C) and heating rate (10 °C/min and 110 °C/min) were examined in a lab-scale fixed-bed pyrolyser, with a particular focus on the secondary cracking extents of the liquid tar. Through both experimental investigation and modelling approach, it was found that significant secondary cracking extent occurred upon the increase in the feedstock size, heating rate and residence time. Upon the fast pyrolysis, the average temperature gap between the centres of the coarse particle and reactor wall could reach a maximum of 115 °C for the tyre chips of 6–15 mm. Consequently, its primary volatiles underwent the secondary cracking reaction at an overall extent of 17% at a terminal temperature of 600 °C and a fast heating rate of 110 °C/min. Consequently, the yield of light gases including methane was increased remarkably. The flow rate of inert carrier gas was also influential in the secondary cracking, in which a maximum tar yield (54 wt%) was reached at a carrier gas flow rate of 1.5 L/min. This indicates the occurrence of secondary cracking has been largely minimised. At a pyrolysis temperature of 600 °C, the addition of CO2 in the carrier gas had an insignificant effect on the product yield distribution under the slow heating scheme. In contrast, the addition of steam resulted in a slight increase of carbon monoxide, presumably due to the occurrence of gasification reaction.

In this paper, the properties and leaching propensity of weathered Victorian brown coal fly ash have been investigated. This study was conducted to assess if the weathered ash could replace fresh fly ash in mineral carbonation process. Through the use of a variety of advanced instruments, the mineralogical properties of weathered fly ash have been investigated. In addition, the leaching of such a fly ash in the mixture of ammonium chloride and sole hydrochloric acid has been examined. As has been confirmed, the weathered fly ash is dominated by hydrates and carbonates which were formed in aqueous landfilling system. These species were mostly poorly crystallized, and even loosely agglomerated into clusters in the weathered fly ash. Irrespective of the leaching reagent, the target Ca and Mg in weathered fly ash were more easily extracted than in the fresh ash counterpart under the same leaching conditions. In addition, for the use of either leaching agent, the temperature and time played little or marginal role on the extraction of target Ca and Mg out of the weathered fly ash sample. Decreasing the pH of the leaching agent is beneficial in enhancing the extraction of Ca and Mg, at a cost of a gradually lowered selectivity due to the simultaneous elution of impure elements. The optimum pH value was found to be around 4 for the mixture of NH 4 Cl + HCl, which maximized the extraction yields of Ca and Mg close to ~ 70% at a minimal elution of the impurities. This is attributed to the buffering property of NH 3 and its complexing capability to prevent the dissolution of impure elements. Instead, the use of sole HCl even at the same pH value as the mixture of NH 4 Cl + HCl resulted in a deep penetration of protons into particle inside, the intense breakage of ash cluster, and hence, the simultaneous dissolution of plenty of impurities.

In this paper, a closed-loop multistep process which allows leaching and precipitation of magnesium and calcium as carbonate from Victorian brown coal fly ash has been examined. Victorian brown coal fly ash has a distinctively high concentration of alkaline earth metals and low amounts of aluminum and silica. The main objective here is to clarify the dissolution kinetics of magnesium and calcium in regenerative ammonium chloride and subsequent carbonation of dissolved cations. Instead of a once-through test with fresh ammonium chloride, multiple locked circuits were adopted to assess the leaching capability of regenerated ammonium salt, as well as the accumulation of impurities upon the recycling and reuse of the leaching agent. As has been revealed, upon increasing cycles of ammonium chloride use, the extraction yields of both target cations decreased significantly. Their extraction by ammonium chloride was favored by the presence of the oxide form in the original ash sample, with the extraction of calci...

A model was developed to predict the synergistic effect of D2EHPA and Cyanex 302 on co-extraction of zinc and manganese. The experimental data of zinc and manganese extraction in pH range of 1–5, temperature of 23, 40 and 60 °C and different organic phase composition (D2EHPA and Cyanex 302) were used to propose correlations of distribution coefficients of zinc and manganese by multiple linear regression. The abilities of the model were examined by applying a case study on separation of zinc and manganese from spent alkaline battery by extraction. Effect of pH, temperature, extractant composition and phase volume were considered in the case study. Optimum operating conditions were determined for a multi-stage extraction column using the genetic algorithm as the optimization routine. These optimum operating conditions, including pH, extractant composition, temperature and phase volumetric ratio, were reported for an extraction unit with one, two, three and four equilibrium stages.

In this paper, we present a bacteria growth monitoring technique using a complementary metal-oxide semiconductor capacitive sensor. The proposed platform features a differential capacitive readout architecture with two interdigitized reference and sensing electrodes. These electrodes are exposed to pure Luria-Bertani (LB) medium and Escherichia Coli (E. Coli) bacteria suspended in the LB medium, respectively. In order to direct the solutions toward the electrodes, two microfluidic channels are implemented atop the electrodes through a direct-write assembly technique. We thereafter demonstrate and discuss the experimental results by using two different bacteria concentrations in the order of 10(6) and 10(7) per 1 mL in the LB medium.

The synergistic effect of Cyanex 302 on the extraction of zinc and manganese with D2EHPA in sulfate media was investigated. Experiments were carried out in the pH range of 1.0–5.0, temperature of 23, 40, and 60°C with sole D2EHPA and Cyanex 302 as extractant and D2EHPA to Cyanex 302 ratios of 1:3, 1:1, and 3:1. The experimental results showed that the co-extraction of zinc and manganese increased with increasing equilibrium pH and temperature. Increasing the D2EHPA to Cyanex 302 ratio in the organic phase, caused a left shifting of the extraction isotherm of zinc and a right shifting of the extraction isotherm of manganese. Thus, a better separation of zinc over manganese was achieved. At low pHs, the separation factor is low when pure D2EHPA is used as an extractant; however, using Cyanex 302 as a synergist, the separation factor increases and results in a better separation of zinc from manganese. Stoichiometric coefficient of zinc for single D2EHPA and Cyanex 302 and their mixture was calculated to be c...

We report ultrafast transient-grating measurements of crystals of the three-dimensional Dirac semimetal cadmium arsenide, Cd3As2, at both room temperature and 80 K. After photoexcitation with 1.5-eV photons, charge-carriers relax by two processes, one of duration 500 fs and the other of duration 3.1 ps. By measuring the complex phase of the change in reflectance, we determine that the faster signal corresponds to a decrease in absorption, and the slower signal to a decrease in the light's phase velocity, at the probe energy. We attribute these signals to electrons' filling of phase space, first near the photon energy and later at lower energy. We attribute their decay to cooling by rapid emission of optical phonons, then slower emission of acoustic phonons. We also present evidence that both the electrons and the lattice are strongly heated., 8 pages, 7 figures. Differs from the previous version in incorporating changes made during the review process and new appendices. Differs from the published version in including section headings and in omitting AIP copy-edits. No substantial differences in scientific conclusions from either version

The power output, fill factor (FF), and transient photoconduction characteristics of infrared photothermovoltaic devices comprising mainly semiconducting single-walled carbon nanotubes are studied as a function of incident optical power and temperature. Explicit analytical expressions for the electrical power and FF are derived and verified experimentally. An improvement in the figure of merit is found to counterbalance the effect of FF reduction on the output power under high illumination fluxes. The transient response is shown to be limited by the RC parameter and not by nanotube-associated heat transport processes.

Conformational changes in bovine serum albumin (BSA), Ca++-free α-lactalbumin(apo-α-lac), and Ca++-saturated α-lactalbumin(holo-ct-lac) were examined via Fourier transform infrared (FTIR) spectroscopy after pressure treatment up to 1270 MPa. BSA showed minimal irreversible secondary structural changes with pressurization, showing a slight loss of β-sheet structure in favor of α-helix. Apo-α-lac underwent major irreversible changes and exhibited infrared bands characteristic of aggregation upon decompression. Holo-α-lac showed extensive resistance to high pressure with no major structural changes. The rich disulfide content in BSA and the presence of Ca++ in holo-α-lac may play important roles in stabilizing these proteins against pressure denaturation.

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd3As2 crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. The room-temperature responsivity of the sensor is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the intrinsic bandwidth of the sensor is predicted to approach the terahertz range. The photocurrent depends on the optical power and modulation frequency. Our study demonstrates that crystalline Cd3As2 is a promising material for high-bandwidth and spectrally broad photosensing, imaging, and communication.

Pressure-induced conformational changes in D(2)O solutions of the two genetic variants of beta-lactoglobulin A (beta-lg A) and beta-lactoglobulin B (beta-lg B) and an equal mixture of both variants (beta-lg A+B) were studied by employing variable-pressure Fourier transform infrared (VP-FTIR) spectroscopy. Changes in the secondary structure of beta-lg A were observed at lower pressure compared to beta-lg B, indicating that beta-lg A had a more flexible structure. During the decompression cycle beta-lg A showed protein aggregation, accompanied by an increase in alpha-helical conformation. The changes in the secondary structure of beta-lg B with the pressure were minor and for the most part reversible. Upon decompression no aggregation in beta-lg B was observed. Increasing the pressure from 0.01 to 12.0 kbar of a solution containing beta-lg A+B resulted in substantial broadening of all major amide I bands. This effect was partially reversed by decreasing the hydrostatic pressure. beta-lg A+B underwent less aggregate formation than beta-lg A, possibly as a result of protein-protein interactions between beta-lg A and beta-lg B. Hence, it is likely that the functional or biological attributes of beta-lg proteins may be affected in different ways by hydrostatic pressure.

Our objective was to study skin disorders in neonates within the first 48 hours of life in Ahvaz, Iran. One thousand consecutive neonates were examined in a descriptional prospective cohort study for 1 year (2002–03). The rate of skin disorders and their relationship to age of gestation and sex were calculated and analyzed using the computerized program spss version 10 and chi-squared test (χ2). Our findings were Mongolian spots (71.3%), Epstein pearls (70.2%), sebaceous hyperplasia (43.7%), salmon patch (26.2%), hypertrichosis (25.7%), erythema toxicum (11.1%), milia (7.5%), desquamation (1.9%), hemangioma (1.3%), and miliaria (1.3%). The most frequent skin disorders were Mongolian spots, Epstein pearls, and sebaceous hyperplasia. Differences between our study findings and those of others may be based on racial differences and study method.

Highly luminescent, core–shell, single-walled carbon nanotube–poly[2-methoxy-5-(2′-ethylhexyloxy)−1,4-phenylene vinylene] (MEH-PPV) one-dimensional networks were synthesized by a multicycle unstable micellization method. The current–voltage data indicated that the charge transport within the nanowire network remained Ohmic, with the differential conductance scaling linearly with temperature in the temperature range of about 120 to 300 K. Further analysis based on the comparative study involving photoluminescence and Raman spectroscopic tests pointed to interchain interactions and nanotube–polymer interface as primary factors influencing the electronic characteristics of the processed samples. Likewise, steady-state photoconduction tests confirmed that the heterointerface played a dominant role behind the increased photoresponse induced by exciton annihilation at a low bias regime. The study helped us identify the underlying physical mechanisms that controlled the optical, electrical, and photoconduction properties of the MEH-PPV–carbon nanotube heteronetworks. Potentially, this will open a door to the development of next generation, low-cost, all-organic nanooptoelectronic devices and systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40029.

This work presents the concept of a monolithic concrete-integrated dye-synthesized photovoltaic solar cell for optical-to-electrical energy conversion and on-site power generation. The transport measurements carried out in the dark revealed the presence of VOC of ~190 mV and ISC of ~9 μA, induced by the electrochemical conversion of concrete-supplied ionic impurities at the electrodes. The current-voltage measurements performed under illumination at incident optical powers of ~46 mW confirmed the generation of electrical power of ~0.64 μW with almost half generated via battery effect. This work presents a first step towards realizing the additional pathways to low-cost electrical power production in urban environments based on a combined use of organic dyes, nanotitania and concrete technology.

Thermo-electric generators (TEGs) directly convert thermal into electrical energy and are the prime candidates for application in low-grade thermal energy/heat waste recovery. TEGs possess several critical advantages as they remain silent, highly reliable and lightweight, which make them uniquely suited for niche deployments in transportation, space satellites, electronics cooling and thermo-voltaic cells. With the efficiency in a few percent range, the efficiency-to-cost ratio remains poor, with the bottleneck traced back to the thermo-electric (TE) materials. PbTe and Bi2Te3, two key TE materials that are in commercial operation, have room temperature ZT of less than 1, whereas ZT exceeding 3 is required for a TEG to be economically viable. Until recently, the enhancement of ZT was mainly attained by introducing phonon scattering interfaces and rattling centers to slow heat transport. With thermal conductivity already approaching the fundamental limit of amorphous materials, further gain in ZT can be only realized by improving the thermo-electric power factor, S2, typically via costly band structure engineering or by means of quantum confinement. In this work, we instead focus on Cd3As2, a high performance 3D Dirac semimetal. Compared to other semimetals, Cd3As2 possess Dirac fermions that disperse linearly in k3-space and in turn, one of the largest electron mobilities known for crystalline materials, i.e. ~104-105cm2V-1s-1. The carrier back-scattering remains suppressed and the electrical transport is dominated by high-energy carriers that favorably affect the thermopower of Cd3As2. Since the power factor scales with the carrier mobility, μ, and weighted density-of-states effective mass, i.e. S2 ~ μ, and the lattice thermal conductivity is within amorphous limit for this material, Cd3As2 shows a strong potential for demonstrating high, device-favorable S and in turn ZT. A reduced temperature vapor-based crystallization pathway was developed to produce free standing, stochiometric 2D cm-size crystals in Cd3As2. In contrast to previous findings, the Seebeck coefficient is seen to initially rise linearly with T to reach a peak within ~ 300-400 K range which is followed by a decline with the shift in the trend attributed to the increase in the role of the ambipolar heat transfer as temperature increases.The primary mechanism of the minority carrier generation in our samples is attributed to phonon-assisted interband electronic transitions involving E and A1 bands. Possessing a very high room-temperature thermopowers of ~613 uV/K and amorphous limit thermal conductivity, bulk Cd3As2 is identified as another high promise phonon-glass electron-crystal TE material for development of next generation a high efficiency thermo-electric generators and refrigerators operating under normal conditions. Figure 1

Much of our food directly or indirectly originates from plant material; thus, detailed studies on plant contamination processes are an essential part of international environmental research. This overview attempts to identify and describe the most important parameters and processes affecting the behaviour of radionuclide transfer to plants. Many parameters influence these processes. These parameters are related to: (1) plant, (2) soil, (3) radionuclide, (4) climate and (5) time. Often there is no boundary between the factors and they are linked to each other. Knowledge of important factors in radionuclide transfer to plants can help to assess and prevent radiological exposure of humans. This knowledge can also help to guide researches and modelling related to transfer of radionuclides to food chain.

Vertically integrated graphene-semiconductor systems remain of significant technological importance for their promise to captivate new device physics and propel the development of advanced carbon-based opto-electronic devices. In this study, we carry out a series of bias-dependent transport, gate-dependent transport, and photoconduction measurements to probe the opto-electronic characteristics of metal-graphene-4H-SiC (0001) (Si-face) heterojunctions. The forward bias transport is found to deviate strongly from thermionic emission one as being controlled by the device circuitry and minority carrier injection mechanisms. An improved analytical model is offered and used to extract key junction parameters including series resistance of ∼80 kΩ, interface barrier height of ∼0.6 eV, and ideality factor of ∼6.1. The results of the photocurrent tests point to a light-assisted minority carrier injection as a key mechanism behind the photoconductive gain obtained in the devices subject to a weak, sub-bandgap cw-excitation.

Patterning graphene with noble metal plasmonic nanostructures to enhance and to manipulate the optical and electronic properties of graphene promises a variety of technological innovations in the field of nano-optoelectronics. In this report, we briefly revisit photoconduction experiments done recently on graphene plasmonic sensors and show that the excess electrical current generated in response to spatially non-uniform optical excitation is primarily induced by a photo-thermo-electric effect in the graphene itself. As this mechanism has nothing to do with the excess free carrier generation common with conventional semiconductors, the plasmonic nanostructures cannot be utilized to regulate the free carrier density and doping of graphene, in contrast to what has been proposed recently.

Time-dependent wet-processing of HiPCo nanotubes in ~ 0.5 M phosphoric acid and its effect on the structural, transport, infrared light absorption and photoconduction characteristics have been studied. Nanotubes were treated for nominal time intervals of 1, 2 and 3 h. The treatment is found to be a two-step process that initially results in the removal/partial replacement of most pre-existing C-O , O–H and CH x groups with phosphorous oxy and carbonyl groups. According to T-dependent current–voltage measurements, the differential conductance, G of nanotube network varies with temperature as ~ Ta, with a exhibiting a slight increase as a result of the treatment, attributed to a slight increase in disorder and not doping effects. The nanotubes processed for three hours also show an order of magnitude improvement in photoconduction response time compared to that of untreated tubes, with growth/decay characteristic time constants approaching a sub-second range.

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