Quantification of the morphological transition in cadmium selenide nanocrystals as a function of reaction temperature

Controlling the morphology of semiconductor nanocrystals has typically relied on controlling the concentration and species of surface ligands utilized in synthesis. Specific shapes, such as branched structures are of particular interest as the light harvesting and charge separating layer in a photovoltaic device. In this work we quantify how changes in the reaction temperature affect the resulting morphology of the nanocrystals. The narrowness of the temperature range over which the morphological transition occurred provides guidance to the tolerances necessary in the synthesis of CdSe utilized in commercial devices on a large scale.     

Inspection of lymph nodes for caseous lymphadenitis and its effect on the density of microbes on sheep carcasses

This study aimed to measure the amount of microbial contamination caused by inspecting the lymph nodes of adult sheep carcasses for caseous lymphadenitis (CLA). Surface swabs from carcasses pre-inspection (N=296) and post-inspection (N=296) were obtained for enumeration of indicator organisms at three commercial abattoirs. At the scapular site, inspection doubled the probability of detecting E. coli (Pr before=0.35, Pr after=0.67) and increased the expected count of E. coli from 2cfu/cm(2) to 13cfu/cm(2). Inspection at the rump site increased the probability of detecting E. coli by 1.1 times (Pr before=0.84, Pr after=0.93) and increased the expected count from 32cfu/cm(2) to 45cfu/cm(2). Effects were also observed for Enterobacteriaceae and total viable count. The findings show that routine inspection of adult sheep carcasses for CLA has a detrimental impact on carcass microbiological traits.     

Sequestration of zinc from zinc oxide nanoparticles and life cycle effects in the sediment dweller amphipod Corophium volutator

We studied the effects of ZnO nanoparticles [ZnO NPs, primary particle size 35 ± 10 nm (circular diameter, TEM)], bulk [160 ± 81 nm (circular diameter, TEM)], and Zn ions (from ZnCl(2)) on mortality, growth, and reproductive endpoints in the sediment dwelling marine amphipod Corophium volutator over a complete lifecycle (100 days). ZnO NPs were characterized by size, aggregation, morphology, dissolution, and surface properties. ZnO NPs underwent aggregation and partial dissolution in the seawater exposure medium, resulting in a size distribution that ranged in size from discrete nanoparticles to the largest aggregate of several micrometers. Exposure via water to all forms of zinc in the range of 0.2-1.0 mg L(-1) delayed growth and affected the reproductive outcome of the exposed populations. STEM-EDX analysis was used to characterize insoluble zinc precipitates (sphaerites) of high sulfur content, which accumulated in the hepatopancreas following exposures. The elemental composition of the sphaerites did not differ for ZnO NP, Zn(2+), and bulk ZnO exposed organisms. These results provide an illustration of the comparable toxicity of Zn in bulk, soluble, and nanoscale forms on critical lifecycle parameters in a sediment dwelling organism.     

Speciation and distribution of alkali,alkali earth metals and major ash forming elements during gasification of fuel cane bagasse

Gasification of fuel cane bagasse, the waste residue from fuel cane, a hybrid of wild and commercial clones of sugar cane, was carried out in a novel 50 kWe air-blown autothermal downdraft gasifier. The speciation and distribution of alkali, alkali earth metals and major ash forming elements during gasification were investigated to evaluate the extent of volatilisation of these elements into the syngas and to determine the likely impact on syngas fuelled solid oxide fuel cell systems. Also assessed was the potential for defluidisation of the fuel bed due to agglomerate and deposit formation. Chemical fractionation studies showed that 30% of the potassium was captured by aluminosilicates and was retained in the ash, thereby reducing the alkali loading in the syngas and that more than 50% of the alkali earth metals were released to the syngas. In contrast, although the major ash forming elements were transformed from acid insoluble to acid soluble forms during gasification they remained hard bound in the ash and less than 30% of each one was released into the gas phase. The composition of clinkers and agglomerates produced during gasification was investigated by SEM-EDX and XRD which confirmed the presence of the eutectic systems KAlSi₂O₆–SiO₂, KAlSi₂O₆–CaMgSi₂O₆–SiO₂ and CaMgSi₂O₆–NaAlSi₃O₈. A preliminary model of the distribution behaviour during gasification of the ash forming elements has been developed.     

Influence of an Electric Field on the Burning Behavior of Solid Fuels and Propellants

An experimental study on the effects of an applied external electric field on the combustion behavior of solid fuels and solid propellants has been conducted. In an opposed flow burning configuration, application of an electric field was shown to extinguish a paraffin fuel and gaseous oxygen flame over a broad range of operating conditions. When subjected to the electric field, burning paraffin fuel strands were found to extinguish at various axial locations relative to the exit of the oxidizer gas jet. Extinguishment location was found to be a function of field strength as well as electrode surface area, while changes in polarity did not significantly alter the results. In addition, the combustion behaviors of two composite solid rocket propellants were studied while subjected to an external electric field. Both propellants were based on HTPB/AP combinations, with one propellant containing aluminum and the other being non‐aluminized. Application of an electric field to the composite solid rocket propellant strands demonstrated decreases in propellant burning rate under all operating conditions for both propellants including changes in polarity. The flame structure of the aluminized propellant was examined closely as the luminosity, flame length, and flame width varied significantly with field strength and burning location of the strand relative to the electrodes.     

Complementary integrated circuits on plastic foil using inkjet printed n- and p-type organic semiconductors: Fabrication,characterization, and circuit analysis

Complementary thin-film transistor circuits composed of 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS–PEN) and a rylene carboxylic diimide derivative for p- and n-channel thin-film transistors (TFTs) were fabricated on flexible foils. The so-called staggered TFT configuration is used, meaning that the semiconductors layers are deposited last. The work-function of the injecting gold electrodes were modified using several self-assembled monolayers (SAMs). For optimized contacts the mobility of the n- and p-channel TFTs was 0.5 cm²/Vs and 0.2 cm²/Vs, respectively. Strongly degraded performance is obtained when the n-channel material was printed on contacts optimized for the p-channel TFT, and vice versa. This illustrates that for CMOS circuits we need careful work-function engineering to allow proper injection for both electrons and holes. We show for the first time that by using a bimolecular mixture for the SAM we can systematically vary the work function, and demonstrate how this affects the performance of discrete n-type and p-type transistors, as well as CMOS inverters and ring oscillators. Under optimal processing conditions we realized complementary 19-stage ring oscillators with 10 μs stage delay operating at 20 V.     

N,7,7‐Tricyanoquinomethanimine (TCQMI) Based Organic Magnetic Materials

The synthesis and characterization of a new family of magnetic materials based on the electron accepting cyanocarbon N,7,7‐tricyanoquinomethanimine, TCQMI, its radical anion [TCQMI], and its σ‐dimer, σ‐[TCQMI]₂^2?, are reported. [Fe^IIICp*₂][TCQMI] (where Cp* is pentamethylcyclopentadienide) forms parallel chains of alternating [TCQMI]^?? and [FeCp*₂]^?+ and magnetically orders at 3.4 K as a weak ferromagnet. M[TCQMI]₂?zCH₂Cl₂ (M = V, Fe) are amorphous solids with [TCQMI]^?? coordinated to metal centers through the nitrile groups. The Fe compound magnetically orders as a weak ferromagnet at ≈4 K, whereas the V compound shows no evidence of magnetic ordering. {[Mn^IIITPP]⁺}₂[TCQMI]₂^2? (TPP = tetraphenylporphyrin) results from the reaction of TCQMI with Mn^IITPP(py) due to the formation of the [TCQMI]₂^2? σ‐dimer in situ, and is a weak ferromagnet below 3.7 K. The lack of magnetic ordering in V[TCQMI]₂?zCH₂Cl₂ is not currently understood, and is in strong contrast to V[TCNE]₂?zCH₂Cl₂, which magnetically orders above room temperature.     

Myeloid-Derived Suppressor Cells Gain Suppressive Function during Neonatal Bacterial Sepsis

Neonates are at an increased risk of an infectious disease. This is consistent with an increased abundance of myeloid-derived suppressor cells (MDSCs) compared with older children and adults. Using a murine model of neonatal bacterial sepsis, we demonstrate that MDSCs modulate their activity during an infection to enhance immune suppressive functions. A gene expression analysis shows that MDSCs increased NOS2, Arg-1 and IL-27p28 expression in vitro and in vivo in response to Escherichia coli O1:K1:H7 and this is regulated at the level of the gene expression. Changes in the effector gene expression are consistent with increased enzymatic activity and cytokine secretion. The neonatal MDSCs express toll-like receptor (TLR) 2, 4 and 5 capable of recognizing pathogen-associated molecular patterns (PAMPS) on E. coli. However, a variable level of effector expression was achieved in response to LPS, peptidoglycan or flagellin. Individual bacterial PAMPs did not stimulate the expression of Arg-l and IL-27p28 equivalently to E. coli. However, the upregulation of NOS2 was achieved in response to LPS, peptidoglycan and flagella. The increased immune suppressive profile translated to an enhanced suppression of CD4+ T cell proliferation. Collectively, these findings increase our understanding of the dynamic nature of MDSC activity and suggest that these cells abundant in early life can acquire activity during an infection that suppresses protective immunity.     

Measuring degradation rates of PV systems without irradiance data

A method to report photovoltaic (PV) system degradation rates without using irradiance data is demonstrated. First, a set of relative degradation rates are determined by comparing daily AC final yields from a group of PV systems relative to the average final yield of all the PV systems. Then, the difference between relative and absolute degradation rates is estimated using a Bayesian statistical analysis. This approach is verified by comparing to methods that utilize irradiance data. This approach is significant because PV systems are often deployed without irradiance sensors, so the analysis method described here may enable measurements of degradation using data that were previously thought to be unsuitable for degradation studies. Copyright © 2013 John Wiley & Sons, Ltd.