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Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications

Nano Research 2019年第5期12卷 1041-1047页

作者： Md Tanvir Hasan Roberto Gonzalez-Rodriguez Conor Ryan Kristof Pota Kayla Green jeffery l.coffer Anton V.Naumov Department of Physics and Astronomy Texas Christian UniversityTCU Box 298840Fort WorthTexas 76129USA Department cf Chemistry and Eiochemistry Texas Christian UniversityTCU Box 298860Fort WorthTexas 76129USA

In this work,we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal *** and optical properties of as-produced NGQDs are further modified using controlled ozone ***-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and/D//G Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen *** with structural modifications,GQDs experience decrease in ultraviolet-visible (UV-vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR)(up to 45 min treatment) *** allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase,while controlled emission quenching was achieved by either blue laser or thermal *** Oz-NGQDs were further used to form a photoactive layer of solar calls with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current *** study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.

关键词： nitrogen-doped graphene quantum dots ozone treatment optical properties photovoltaics solar cells

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looking ahead to significant improvements in mining safety and health through innovative research and effective diffusion into the industry

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International Journal of Mining Science and Technology 2015年第3期25卷 325-332页

作者： jeffery l.Kohler The Pennsylvania State University

Mining safety and health improvements over the past decades are remarkable by many metrics, and yet the expectation of society, and the goal of the mining industry, is zero harm. If we examine the underlying enablers for the significant gains that have been achieved, the key role that research to help understand the causes of problems and to develop lasting solutions is clear. Many of the remaining challenges have been resistant to solutions by various approaches. Some, such as fatalities and injuries from ground control or powered haulage are prominent year after year. Different approaches are indicated and new solutions will be required if we are to achieve a goal of zero harm. These will originate with research, but into which topics, and what are some of these different approaches? This paper examines the current state of mine safety in the United States and highlights areas of significant opportunity for research that will lead to solutions. The likely direction of research that will enable realization of the ‘‘zero harm'' goal is described in terms of evolutionary and revolutionary approaches. Both are important, but the author's view is that some of the largest gains will be made with trans-disciplinary approaches that break from the past. Topical areas of research are suggested and several research questions are given to illustrate the direction of future research in mining safety and health.

关键词： Mining safety Mining health Mining research Health and safety management systems

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Endocrine impact of Helicobacter pylori:Focus on ghrelin and ghrelin o-acyltransferase

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World Journal of Gastroenterology 2011年第10期17卷 1249-1260页

作者： Penny l jeffery Michael A McGuckin Sara K linden Mucosal Diseases Program Mater Medical Research InstituteMater Health Services Mucosal Immunobiology and Vaccine Center Sahlgrenska AcademyUniversity of Gothenburg

Ghrelin is predominantly produced by the gastric enteroendocrine cell compartment and is octanoylated by the recently discovered ghrelin o-acyltransferase （GOAT） before secretion into the bloodstream. This octanoylation is essential for many of the biological properties of ghrelin including appetite stimulation and anti-inflammatory properties as only the acylated form of ghrelin binds to the ghrelin receptor, the growth hormone secretagogue receptor （GHS-R）. Given the gastric location of ghrelin production, it is perhaps not surprising that insult to the gastric mucosa affects circulating ghrelin levels in humans. Helicobacter pylori （H. pylon） infects more than fifty percent of the world＇s population and once established within the gastric mucosa, can persist for life. Infection is associated with chronic gastritis, gastric atrophy and ulceration, reduced appetite and a lower body mass index （BMI）. The large majority of studies investigating levels of circulating ghrelin and ghrelin expression in the stomach in patients with H. pylori infection indicate that the bacterium has a negative impact on ghrelin production and/or secretion. Eradication of infection restores ghrelin, improves appetite and increases BMI in some studies, however, a causative relationship between H. pylori-associated serum ghrelin decline and food intake and obesity has not been established. Most studies measure total ghrelin in the circulation although the measurement of the ratio of acyl/total ghrelin gives a clearer indication that the ghrelin acylation process is altered during infection and atrophy. GOAT is essential for the production of biologically-active, acyl ghrelin and the impact of H. pylori on GOAT expression and activity will be highly informative in the future.

关键词： Appetite Ghrelin Ghrelin o-acyltransferase Helicobacterpylori Infection Inflammation Obesity

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Old dogs with new tricks:intra-axonal translation of nuclear proteins

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Neural Regeneration Research 2015年第10期10卷 1560-1562页

作者： jeffery l.Twiss Tanuja T.Merianda Department of Biological Sciences University of South Carolina Department of Neurobiology and Anatomy Drexel University College of Medicine

Many different types of polarized eukaryotic cells have been shown to segregate synthesis for some protein subpopulations to cytoplasmic domains distant from their *** neurons,these distances can be tens-to-thousands ... 详细信息

关键词： HMGN Old dogs with new tricks RNA

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Intra-axonal protein synthesis–a new target for neural repair?

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Neural Regeneration Research 2016年第9期11卷 1365-1367页

作者： jeffery l.Twiss Ashley l.Kalinski Rahul Sachdeva John D.Houle Department of Biological Sciences University of South Carolina Department of Neurobiology and Anatomy Drexel University College of Medicine

Although initially argued to be a feature of immature neurons with incomplete polarization, there is clear evidence that neurons in the peripheral nervous system retain the capacity for intra-axonal protein synthe- sis well into adulthood. This localized protein synthesis has been shown to contribute to injury signaling and axon regeneration in peripheral nerves. Recent works point to potential for protein synthesis in axons of the vertebrate central nervous system, mRNAs and protein synthesis machinery have now been docu- mented in lamprey, mouse, and rat spinal cord axons. Intra-axonal protein synthesis appears to be activated in adult vertebrate spinal cord axons when they are regeneration-competent. Rat spinal cord axons regen- erating into a peripheral nerve graft contain mRNAs and markers of activated translational machinery. Indeed, levels of some growth-associated mRNAs in these spinal cord axons are comparable to the regen- erating sciatic nerve. Markers of active translation tend to decrease when these axons stop growing, but can be reactivated by a second axotomy. These emerging observations raise the possibility that mRNA transport into and translation within axons could be targeted to facilitate regeneration in both the peripheral and central nervous systems.

关键词： mRNA transport translational control RNA binding protein axon regeneration spinal cord injury peripheral nerve injury

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Dish-like higher-ordered palladium nanostructures through metal ion-ligand complexation

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Nano Research 2018年第6期11卷 3442-3452页

作者： Xi Yin Miao Shi Kam Sang Kwok Haidong Zhao Danielle l. Gray jeffery A. Bertke Hong Yang Department of Chemical and Biomolecular Engineering University of Illinois at Urbana-Champaign MC-712 206 Roger Adams I Laboratory 600 S. Matthews Avenue Urbana Illinois 61801 USA George l. Clark X-ray Facility University of Illinois at Urbana-Champaign 505 S. Matthews Avenue Urbana Illinois 61801 USA

Unlike nucleation and growth in simple precipitation processes, described by the classical theory, metal nanoparticles formed in organic solvents with capping ligands often involve chemical reactions that occur homogeneously in solution or heterogeneously on the metal surface. These chemical reactions lead to the formation of intermediates that occurs in the process of deposition onto nuclei during the reduction. The understanding of these chemical reactions would enable a better design of functional metal nanocrystals, even those with unconventional hierarchical morphologies. In this study, we report the formation of dish-shaped nanostructures of palladium （Pd） obtained from palladium acetylacetonate （Pd（acac）2） in the presence of oleylamine and oleic acid. The process was correlated with the kinetic-controlled evolution of two-dimensional （2D） Pd nanosheets. The formation of Pd-ligand complexes was revealed using single-crystal X-ray diffraction, ultraviolet-visible spectroscopy, and mass spectrometry. These intermediates affected the formation kinetics of the 2D nanostructures and higher-ordered morphology of the nanodishes.

关键词： palladium nanoplates two-dimensional materials. complexation nucleation growth

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EASE-DGGS:a hybrid discrete global grid system for Earth sciences

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Big Earth Data 2022年第3期6卷 340-357页

作者： jeffery A.Thompson Mary J.Brodzik Kevin A.T.Silverstein Mason A.Hurley Nathan l.Carlson Minnesota Supercomputing Institute University of MinnesotaMinneapolisMNUSA GEMS Informatics Initiative University of MinnesotaMinneapolisMNUSA National Snow and Ice Data Center Cooperative Institute for Research in Environmental SciencesUniversity of ColoradoBoulderCOUSA

Although we live in an era of unprecedented quantities and access to data,deriving actionable information from raw data is a hard *** observation systems(EOS)have experienced rapid growth and uptake in recent decades,and the rate at which we obtain remotely sensed images is *** significant effort and attention has been devoted to designing systems that deliver analytics ready imagery faster,less attention has been devoted to developing analytical frameworks that enable EOS to be seamlessly integrated with other data for quantitative *** global grid systems(DGGS)have been proposed as one potential solution that addresses the challenge of geospatial data integration and ***,we propose the systematic extension of EASE-Grid in order to provide DGGS-like characteristics for EOS data *** describe the extensions as well as present implementation as an application programming interface(API),which forms part of the University of Minnesota’s GEMS(Genetic x Environment x Management x Socioeconomic)Informatics Center’s API portfolio.

关键词： Discrete global grid systems DGGS EASE Grid coordinate reference systems

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Effect of drought stress on male fertility restoration in A3 CMS-inducing cytoplasm of sorghum

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The Crop Journal 2017年第4期5卷 282-289页

作者： Valentin V.Kozhemyakin lev A.Elkonin jeffery A.Dahlberg Department of Biotechnology Agricultural Research Institute of South-East Region Tulaikov Street 7 Saratov 410010 Russia Kearney Agricultural Research & Extension (KARE) 9240 South Riverbend Avenue Parlier CA 93648 USA

Use of cytoplasmic male sterility (CMS) in hybrid breeding requires effective male fertility-restoring lines. In sorghum, very few restoring lines that can restore fertility in A_3 CMS have been reported. To identify the reasons for this deficiency, F_1 and F_2 hybrids of an A_3 CMS line crossed with the line IS1112C, a donor of fertility-restoring (Rf) genes for A_3 cytoplasm, and testcrosses of fertile plants to A_3CMS lines were grown under contrasting water availability regimes in dryland and irrigated field plots. In the irrigated plots the frequency of fertile plants in testcrosses was twice that in dryland plots (P le plants from the F_2 family grown in the irrigated plots showed significantly higher restoration ability than fertile plants from the same family grown in dryland plots. F_3 plants from the F_2 family grown in irrigated plots yielded on average a sixfold higherfrequency of fertile plants in testcrosses than F_3 plants derived from dryland plots (P lity of testcross hybrids correlated negatively with air vapor pressure deficit (VPD) at flowering (r = - 0.96; P lation of Rf genes for A_3 cytoplasm.

关键词： Sorghum bicolor (l.) Moench Cytoplasmic male sterility A3 cytoplasm Fertility-restoring genes Epigenetics Vapor pressure deficit

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Selection and quality assessment of landsat data for the North American forest dynamics forest history maps of the US

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International Journal of Digital Earth 2016年第10期9卷 963-980页

作者： Karen Schleeweis Samuel N.Goward Chengquan Huang John l.Dwyer Jennifer l.Dungan Mary A.lindsey Andrew Michaelis Khaldoun Rishmawi jeffery G.Masek Forest Inventory and Analysis US Forest ServiceRocky Mountain Research StationOgdenUTUSA Department of Geographical Sciences University of MarylandCollege ParkMDUSA U.S.Geological Survey Earth Resources Observation and Science(EROS)Center Sioux FallsSDUSA NASA Ames Research Center Moffett FieldCAUSA Climate Program Office NOAAWashingtonDCUSA NASA Ames Research Center University Corporation Monterey BayMoffett FieldCAUSA NASA Goddard Space Flight Center GreenbeltMDUSA

Using the NASA Earth Exchange platform,the North American Forest Dynamics(NAFD)project mapped forest history wall-to-wall,annually for the contiguous US(1986–2010)using the Vegetation Change Tracker *** with any effort to identify real changes in remotely sensed time-series,data gaps,shifts in seasonality,misregistration,inconsistent radiometry and cloud contamination can be sources of *** discuss the NAFD image selection and processing stream(NISPS)that was designed to minimize these sources of *** NISPS image quality assessments highlighted issues with the landsat archive and metadata including inadequate georegistration,unreliability of the pre-2009 l5 cloud cover assessments algorithm,missing growing-season imagery and paucity of clear *** maps of landsat 5–7 image quantities and qualities are presented that offer novel perspectives on the growing-season archive considered for this *** 150,000+landsat images were considered for the NAFD ***,one high quality cloud-free image in each year or a total of 12,152 images would be ***,to accommodate data gaps and cloud/shadow contamination 23,338 images were *** 220 specific path-row image years no acceptable images were found resulting in data gaps in the annual national map products.

关键词： landsat forest cover change time-series mapping forest disturbance North American forest dynamics nasa earth exchange

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Hybrid energy module for remote environmental observations, experiments, and communications

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Advances in Polar Science 2020年第3期31卷 156-166页

作者： Misha B.KRASSOVSKI jeffery S.RIGGS Chris TAVINO Stan D.WUllSCHlEGER Susan l.HEINZ Environmental Sciences Division Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTN 37831-6290USA Integrated Operations Support Division Oak Ridge National LaboratoryOak RidgeTN 37831-6290USA laboratory Modernization Division Oak Ridge National LaboratoryOak RidgeTN 37831-6290USA

Increased concerns about climate change have led to a significant expansion of monitoring, observational, and experimental sites in remote areas of the world. Meanwhile, advances in technology and availability of low-power equipment have allowed increasingly sophisticated measurements with a wide variety of instruments. However, the deployment and use of these technologies in remote locations is often restricted not only by harsh environmental conditions, but also by the availability of electrical power and communication options. In some cases, research stations and military installations can provide power for scientific equipment, data acquisition, storage, and transmission. Clustering of research sites near existing infrastructure has had the unintended consequence of limiting a spatial understanding of large geographic regions. Fortunately, the modern market offers many power and communication solutions, but most of them are oriented toward large industrial applications. Use of those solutions to power a research site is limited because of their cost and need for significant modification for the specific research purposes. Each study has its own unique power requirements and needs for proper instrumentation. A power and communication solution for a vast majority of implementations with or without modification would be of considerable benefit. This article describes design of a universal, scalable hybrid energy module for the Next-Generation Ecosystem Experiments Arctic project(https://***/). Two modules were built, and the authors describe their implementation and findings over a 2-year period at a remote field site on the Seward Peninsula in western Alaska, USA.

关键词： solar energy wind energy communications power sources alternative energy NGEE Arctic

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