Effect of aluminum oxide doping on the structural, electrical, and optical properties of zinc oxide (AOZO) nanofibers synthesized by electrospinning

Lotus, A.F.,Kang, Y.C.,Walker, J.I.,Ramsier, R.D.,Chase, G.G. Elsevier 2010 Materials science and engineering B. Advanced Func Vol.166 No.1

Zinc oxide nanofibers doped with aluminum oxide were prepared by sol-gel processing and electrospinning techniques using polyvinylpyrrolidone (PVP), zinc acetate and aluminum acetate as precursors. The resulting nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy, and current-voltage (I-V) properties. The nanofibers had diameters in the range of 60-150nm. The incorporation of aluminum oxide resulted in a decrease in the crystallite sizes of the zinc oxide nanofibers. Aluminum oxide doped zinc oxide (AOZO) nanofibers exhibited lower bandgap energies compared to undoped zinc oxide nanofibers. However, as the aluminum content (Al/(Al+Zn)x100%) was increased from 1.70at.% to 3.20at.% in the electrospinning solution, the bandgap energy increased resulting in lower conductivity. The electrical conductivity of the AOZO samples was found to depend on the amount of aluminum dopant in the matrix as reflected in the changes in oxidation state elucidated from XPS data. Electrospinning was found to be a productive, simple, and easy method for tuning the bandgap energy and conductivity of zinc oxide semiconducting nanofibers.

High-resolution metabolomics of occupational exposure to trichloroethylene

Walker, Douglas I,Uppal, Karan,Zhang, Luoping,Vermeulen, Roel,Smith, Martyn,Hu, Wei,Purdue, Mark P,Tang, Xiaojiang,Reiss, Boris,Kim, Sungkyoon,Li, Laiyu,Huang, Hanlin,Pennell, Kurt D,Jones, Dean P,Rot Oxford University Press 2016 International journal of epidemiology Vol.45 No.5

<P><B>Background:</B> Occupational exposure to trichloroethylene (TCE) has been linked to adverse health outcomes including non-Hodgkin’s lymphoma and kidney and liver cancer; however, TCE’s mode of action for development of these diseases in humans is not well understood.</P><P><B>Methods:</B> Non-targeted metabolomics analysis of plasma obtained from 80 TCE-exposed workers [full shift exposure range of 0.4 to 230 parts-per-million of air (ppm<SUB>a</SUB>)] and 95 matched controls were completed by ultra-high resolution mass spectrometry. Biological response to TCE exposure was determined using a metabolome-wide association study (MWAS) framework, with metabolic changes and plasma TCE metabolites evaluated by dose-response and pathway enrichment. Biological perturbations were then linked to immunological, renal and exposure molecular markers measured in the same population.</P><P><B>Results:</B> Metabolic features associated with TCE exposure included known TCE metabolites, unidentifiable chlorinated compounds and endogenous metabolites. Exposure resulted in a systemic response in endogenous metabolism, including disruption in purine catabolism and decreases in sulphur amino acid and bile acid biosynthesis pathways. Metabolite associations with TCE exposure included uric acid (<I>β</I> = 0.13, <I>P</I>-value = 3.6 × 10<SUP>−5</SUP>), glutamine (<I>β</I> = 0.08, <I>P</I>-value = 0.0013), cystine (<I>β</I> = 0.75, <I>P</I>-value = 0.0022), methylthioadenosine (<I>β</I> = −1.6, <I>P</I>-value = 0.0043), taurine (<I>β</I> = −2.4, <I>P</I>-value = 0.0011) and chenodeoxycholic acid (<I>β</I> = −1.3, <I>P</I>-value = 0.0039), which are consistent with known toxic effects of TCE, including immunosuppression, hepatotoxicity and nephrotoxicity. Correlation with additional exposure markers and physiological endpoints supported known disease associations.</P><P><B>Conclusions:</B> High-resolution metabolomics correlates measured occupational exposure to internal dose and metabolic response, providing insight into molecular mechanisms of exposure-related disease aetiology.</P>

A central role for PBP2 in the activation of peptidoglycan polymerization by the bacterial cell elongation machinery

Rohs, Patricia D. A.,Buss, Jackson,Sim, Sue I.,Squyres, Georgia R.,Srisuknimit, Veerasak,Smith, Mandy,Cho, Hongbaek,Sjodt, Megan,Kruse, Andrew C.,Garner, Ethan C.,Walker, Suzanne,Kahne, Daniel E.,Bern Public Library of Science 2018 PLoS genetics Vol.14 No.10

<▼1><P>Cell elongation in rod-shaped bacteria is mediated by the Rod system, a conserved morphogenic complex that spatially controls cell wall assembly by the glycan polymerase RodA and crosslinking enzyme PBP2. Using <I>Escherichia coli</I> as a model system, we identified a PBP2 variant that promotes Rod system function when essential accessory components of the machinery are inactivated. This PBP2 variant hyperactivates cell wall synthesis in vivo and stimulates the activity of RodA-PBP2 complexes in vitro. Cells with the activated synthase also exhibited enhanced polymerization of the actin-like MreB component of the Rod system. Our results define an activation pathway governing Rod system function in which PBP2 conformation plays a central role in stimulating both glycan polymerization by its partner RodA and the formation of cytoskeletal filaments of MreB to orient cell wall assembly. In light of these results, previously isolated mutations that activate cytokinesis suggest that an analogous pathway may also control cell wall synthesis by the division machinery.</P></▼1><▼2><P><B>Author summary</B></P><P>The cell wall of bacteria determines their shape and protects them from osmotic lysis. Two enzymatic activities are required for cell wall synthesis: glycan polymerization and crosslinking. A major new family of glycan polymerases was recently discovered and was proposed to work in complex with crosslinking enzymes called penicillin-binding proteins (PBPs). How the activities of these enzymes are coordinated to prevent the toxic generation of uncrosslinked glycans has remained unknown. Our analysis of the cell elongation system of <I>Escherichia coli</I> has revealed that this coupling is mediated by changes in the PBP that activate glycan chain synthesis by the polymerase. Furthermore, we present genetic evidence that this activation event is mediated by a component of the elongation machinery with a previously unknown function. Discovery of this activation pathway provides new mechanistic insight into the cell wall biogenesis process and identifies a new avenue to disrupt it for antibiotic development.</P></▼2>

Investigation of the depolarisation transition in Bi-based relaxor ferroelectrics

Woodward, David I.,Dittmer, Robert,Jo, Wook,Walker, David,Keeble, Dean S.,Dale, Matthew W.,Rö,del, Jü,rgen,Thomas, Pam A. American Institute of Physics 2014 JOURNAL OF APPLIED PHYSICS - Vol.115 No.11

Blockade of cannabinoid 1 receptor improves GLP-1R mediated insulin secretion in mice

Gonzalez-Mariscal, I.,Krzysik-Walker, S.M.,Kim, W.,Rouse, M.,Egan, J.M. North-Holland 2016 Molecular and cellular endocrinology Vol.423 No.-

<P>The cannabinoid 1 receptor (CBI) is an important regulator of energy metabolism. Reports of in vivo and in vitro studies give conflicting results regarding its role in insulin secretion, possibly due to circulatory factors, such as incretins. We hypothesized that this receptor may be a regulator of the entero-insular axis. We found that despite lower food consumption and lower body weight postprandial GLP-1 plasma concentrations were increased in CB1(-/-) mice compared to CB1(+/+) mice administered a standard diet or high fat/sugar diet. Upon exogenous GLP-1 treatment, CB1(-/-) mice had increased glucose stimulated insulin secretion. In mouse insulinoma cells, cannabinoids reduced GLP-1R-mediated intracellular CAMP accumulation and subsequent insulin secretion. Importantly, such effects were also evident in human islets, and were prevented by pharmacologic blockade of CB1. Collectively, these findings suggest a novel mechanism in which endocannabinoids are negative modulators of incretin-mediated insulin secretion. (C) 2015 Elsevier Ireland Ltd. All rights reserved.</P>

Studies on the Fluidised Bed Reactor for Wastewater Treatment

BAEK, N. H.,Walker, I. 한국화학공학회 1980 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.18 No.2

이 유동층 폐수처리 방법은 처리능력이 한계점에 이른 기존시설의 확충, 탈질화반응(Denitrification), 산업폐수 처리 등에 응용될 수 있는 공정이다. 주된 특징으로는 박테리아나 원생동물의 성장을 돕고 처리 유용면적을 증대시키기 위해 망상형(reticulated) 유동입자를 사용하고, 그 안에서 호기성 소화(Aerobic Digestion)와 혐기성 소화(Anaerobic Digestion)를 시킬 수 있으며 직접 매립할 수 있는 고밀도의 sludge(5-7%)를 얻을 수 있다. 초기 시험단계인 만큼 값싸고 적절한 유동입자의 확보, 폐수의 시간적·계절적 변화에 따른 영향 규명, 수학적 모델 개발 등 많은 연구가 계속되어야 하지만 기존 공정에 비해 경제성이 높을 것으로, 본 실험연구를 통해 사료된다. This fluidized process seems very promising additions to the range of systems which can be used to up-rate existing sewage treatment plants, for denitrification, and to deal with industrial wastes. Because it retains such an active biomass within supporting particles, it will offer both aerobic digestion find anaerobic one. Concentrated sludges (5-7% dry solids) may be produced for direct land disposal. The ability of this system is still to be tested in such aspects as cheaper and suitable particles and capapility of handling both diurnal and storm flow. However it will show savings in total cost when compared with conventional system.

Source signatures from combined isotopic analyses of PM_2.5 carbonaceous and nitrogen aerosols at the peri-urban Taehwa Research Forest, South Korea in summer and fall

Lim, Saehee,Lee, Meehye,Czimczik, Claudia I.,Joo, Taekyu,Holden, Sandra,Mouteva, Gergana,Santos, Guaciara M.,Xu, Xiaomei,Walker, Jennifer,Kim, Saewung,Kim, Hyun Seok,Kim, Soyoung,Lee, Sanguk Elsevier 2019 Science of the Total Environment Vol.655 No.-

<P><B>Abstract</B></P> <P>Isotopes are essential tools to apportion major sources of aerosols. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM<SUB>2.5</SUB> at Taehwa Research Forest (TRF) near Seoul Metropolitan Area (SMA) during August–October 2014. PM<SUB>2.5</SUB>, TC, and TN concentrations were 19.4 ± 10.1 μg m<SUP>−3</SUP>, 2.6 ± 0.8 μg C m<SUP>−3</SUP>, and 1.4 ± 1.4 μg N m<SUP>−3</SUP>, respectively. The δ<SUP>13</SUP>C of TC and the δ<SUP>15</SUP>N of TN were − 25.4 ± 0.7‰ and 14.6 ± 3.8‰, respectively. EC was dominated by fossil-fuel sources with F<SUB>ff</SUB> (EC) of 78 ± 7%. In contrast, contemporary sources were dominant for TC with F<SUB>c</SUB> (TC) of 76 ± 7%, revealing the significant contribution of contemporary sources to OC during the growing season. The isotopic signature carries more detailed information on sources depending on air mass trajectories. The urban influence was dominant under stagnant condition, which was in reasonable agreement with the estimated δ<SUP>15</SUP>N of NH<SUB>4</SUB> <SUP>+</SUP>. The low δ<SUP>15</SUP>N (7.0 ± 0.2‰) with high TN concentration was apparent in air masses from Shandong province, indicating fossil fuel combustion as major emission source. In contrast, the high δ<SUP>15</SUP>N (16.1 ± 3.2‰) with enhanced TC/TN ratio reveals the impact of biomass burning in the air transported from the far eastern border region of China and Russia. Our findings highlight that the multi-isotopic composition is a useful tool to identify emission sources and to trace regional sources of carbonaceous and nitrogen aerosols.</P> <P><B>Highlights</B></P> <P> <UL> <LI> For PM<SUB>2.5</SUB>, the average δ<SUP>13</SUP>C of TC and δ<SUP>15</SUP>N of TN were −25.4 ± 0.7‰ and 14.6 ± 3.8‰respectively. </LI> <LI> EC and TC were dominated by fossil-fuel (78 ± 7%) and contemporary (76 ± 7%) sources, respectively. </LI> <LI> Low δ<SUP>15</SUP>N (7.0 ± 0.2‰) with high TN concentration was evident in air masses from Shandong province. </LI> <LI> Multi-isotopic composition is useful to trace regional sources of PM<SUB>2.5</SUB> aerosol. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>δ<SUP>13</SUP>C of TC versus f<SUB>M</SUB> (EC) for different levels of δ<SUP>15</SUP>N of TN observed at Taehwa Research Forest (TRF) and Gosan Climate Observatory (GCO). TRF samples were classified into groups according to air mass origin.</P> <P>[DISPLAY OMISSION]</P>

An eight-user UMTS channel unit Processor for 3GPP base station applications

Prokop, T.,Thomas, C.,Bickerstaff, M.,Niemasz, J.,Bernadac, P.,Saintot, P.,Laufer, R.,Bescher, D.,Michel, R.,Walker, B.,Derriennic, F.,Burban, N.,Le Pape, E.,Moreau, J.P.,Cha, I.,Angioni, S.,Mhirsi, K IEEE 2004 IEEE journal of solid-state circuits Vol.39 No.9

We present a multi-user W-CDMA baseband channel unit processor for cellular base station applications. The ASIC is compliant with the 3GPP/UMTS standard and exceeds 3GPP minimum requirements for high-speed data by 2.2-6.2 dB. It supports up to eight users simultaneously, with a mix of voice and data services and a maximum uplink data rate of 384 kb/s and maximum downlink data rate of 2 Mb/s. The ASIC implements preamble detection, searching, demodulation RAKE-finger processing, channel coding/decoding for voice and data services, and transmission functions. It is coupled to a DSP to form a complete channel element for eight users.

Preliminary Thermal and Hydraulic Analysis on the ITER Upper Diagnostic Port Plug During Normal Operation and Baking

Pak, S.,Cheon, M.-S.,Lee, H.G.,Kalish, M.R.,Pitcher, C.S.,Walker, C.I. AMERICAN NUCLEAR SOCIETY, INC. 2009 Fusion science and technology Vol.56 No.1

Juniper Berries Regulate Diabetes and Obesity Markers Through Modulating PPARα, PPARγ, and LXR: In Vitro and In Vivo Effects

Hee-Sung Chae,Olivia Dale,Tahir M. Mir,Mohammad K. Ashfaq,Bharathi Avula,Larry A. Walker,Ikhlas A. Khan,Shabana I. Khan 한국식품영양과학회 2023 Journal of medicinal food Vol.26 No.5

The berries of Juniperus communis have been traditionally used for therapeutic purposes. They have been reported to possess various pharmacological effects such as anti-inflammatory, hypoglycemic and hypolipidemic activities. In this study, a methanolic extract of J. communis berries (JB) was evaluated for its effects on peroxisome proliferator-activated receptors alpha and gamma (PPARα and PPARγ), liver X receptor (LXR), glucose uptake and lipid accumulation using various cellular systems. At a concentration of 25 μg/mL, JB caused 3.77-fold activation of PPARα, 10.90-fold activation of PPARγ, and 4.43-fold activation of LXR in hepatic cells. JB inhibited (11%) the adipogenic effect induced by rosiglitazone in adipocytes and increased glucose uptake (90%) in muscle cells. In high-fat diet (HFD) fed mice, JB at a dose of 25 mg/kg body weight exhibited a 21% decrease in body weight. Fasting glucose levels in mice treated with 12.5 mg/kg of JB were significantly decreased (39%) indicating its efficacy in regulating hyperglycemia and obesity induced by HFD thus ameliorating the symptoms of type 2 diabetes. A series of energy metabolic genes, including Sirt1 (2.00-fold) and RAF1 (2.04-fold), were upregulated by JB, while rosiglitazone regulated the hepatic PPARγ only. Phytochemical analysis of JB indicated presence of a number of flavonoids and biflavonoids which seem to be responsible for the observed activity. It was concluded that JB acted as a multiple agonist of PPARα, PPARγ and LXR without the undesired effect of adipogenesis and exhibited the property of enhancing glucose uptake. The regulation of PPARα, PPARγ and LXR seems to be through Sirt1 and RAF1. In vivo results confirmed the antidiabetic and antiobesity potential of JB and indicated its utility in metabolic disorder and type 2 diabetes.