Ultrathin molybdenum diselenide nanosheets anchored on multi-walled carbon nanotubes as anode composites for high performance sodium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Zhian; Yang, Xing; Fu, Yun; Du, Ke

2015-11-01

Ultrathin molybdenum diselenide nanosheets are decorated on the surface of multi-walled carbon nanotubes (MWCNT) via a one-step hydrothermal method. Uniform MoSe2 nanosheets are firmly anchored on MWCNT according to the characterizations of scanning electron microscope (SEM), transmission electron microscope (TEM). When evaluated as anodes for sodium storage, the MoSe2@MWCNT composites deliver a reversible specific capacity of 459 mAh g-1 at a current of 200 mA g-1 over 90 cycles, and a specific capacity of 385 mAh g-1 even at a current rate of 2000 mAh g-1, which is better than the MoSe2 nanosheets. The enhanced electrochemical performance of the MoSe2@MWCNT composites can be ascribed to the synergic effects of MoSe2 nanosheets and MWCNT. The high capacity and good rate performance reveal that the MoSe2@MWCNT composites are very promising for applications in sodium-ion batteries.

"Fleshing Out Consensus": Radical Pragmatism, Civil Rights, and the Algebra Project

ERIC Educational Resources Information Center

Wahman, Jessica

2009-01-01

It has been said that pragmatism's "merely instrumental" truths fail to motivate radical change whereas absolute ideals make excellent guiding and driving forces for justice. However, in "Radical Equations: Math Literacy and Civil Rights," Robert Moses speaks of the radical success of pragmatic principles, used in the Civil Rights Movement, that…

Evaluation of Progress, Bilingual Mini-Head Start, November 1973.

ERIC Educational Resources Information Center

McConnell, Beverly

A 5-year experimental project, the Bilingual Mini Head Start program is an early education program for children of migrant farm workers. The program has 2 components: the mobile and the stationary components. In the stationary program, 2 year-round centers are operated in Connell and Moses Lake (Washington). These centers' purpose is to…

Multidisciplinary Obstetric Simulated Emergency Scenarios (MOSES): Promoting Patient Safety in Obstetrics with Teamwork-Focused Interprofessional Simulations

ERIC Educational Resources Information Center

Freeth, Della; Ayida, Gubby; Berridge, Emma Jane; Mackintosh, Nicola; Norris, Beverley; Sadler, Chris; Strachan, Alasdair

2009-01-01

Introduction: We describe an example of simulation-based interprofessional continuing education, the multidisciplinary obstetric simulated emergency scenarios (MOSES) course, which was designed to enhance nontechnical skills among obstetric teams and, hence, improve patient safety. Participants' perceptions of MOSES courses, their learning, and…

Inorganic fullerene-like molybdenum selenide with good biocompatibility synthesized by laser ablation in liquids

NASA Astrophysics Data System (ADS)

Wu, Xiaoju; Tian, Xiumei; Chen, Tongming; Zeng, Ao; Yang, Guowei

2018-07-01

The fabrication of inorganic fullerene-like nanoparticles (IFNPs) is an attractive idea due to their unique structures and various potential applications. To date, IFNPs have been made from numerous compounds with layered two-dimensional structures, based on various synthetic methods. Here we have demonstrated for the first time that inorganic fullerene-like molybdenum selenide nanoparticles (MoSe2 IFNPs) can be synthesized by laser ablating a molybdenum selenide target in 30 vol % ethanol/water mixture at ambient temperature and pressure. The formation mechanism was proposed to elucidate the production of MoSe2 IFNPs in the process of laser ablation in liquids (LAL). The appropriate solvent facilitates the condensation of the plasma plume created by LAL to planar MoSe2. Then, laser-induced high temperature and high pressure lead to the formation of a vacancy in the planar MoSe2, causing the generation of nucleation and growth of the MoSe2 IFNPs. In addition, a CCK-8 (cell counting kit-8) assay and a cell viability assay were performed to examine the cytotoxic behavior and the effect on cell viability of MoSe2 IFNPs. The results show that MoSe2 IFNPs are reasonably nontoxic and biocompatible with the given cells, showing they have significant potential in biomedical applications.

Inorganic fullerene-like molybdenum selenide with good biocompatibility synthesized by laser ablation in liquids.

PubMed

Wu, Xiaoju; Tian, Xiumei; Chen, Tongming; Zeng, Ao; Yang, Guowei

2018-07-20

The fabrication of inorganic fullerene-like nanoparticles (IFNPs) is an attractive idea due to their unique structures and various potential applications. To date, IFNPs have been made from numerous compounds with layered two-dimensional structures, based on various synthetic methods. Here we have demonstrated for the first time that inorganic fullerene-like molybdenum selenide nanoparticles (MoSe 2 IFNPs) can be synthesized by laser ablating a molybdenum selenide target in 30 vol % ethanol/water mixture at ambient temperature and pressure. The formation mechanism was proposed to elucidate the production of MoSe 2 IFNPs in the process of laser ablation in liquids (LAL). The appropriate solvent facilitates the condensation of the plasma plume created by LAL to planar MoSe 2 . Then, laser-induced high temperature and high pressure lead to the formation of a vacancy in the planar MoSe 2 , causing the generation of nucleation and growth of the MoSe 2 IFNPs. In addition, a CCK-8 (cell counting kit-8) assay and a cell viability assay were performed to examine the cytotoxic behavior and the effect on cell viability of MoSe 2 IFNPs. The results show that MoSe 2 IFNPs are reasonably nontoxic and biocompatible with the given cells, showing they have significant potential in biomedical applications.

Here's Looking at You: Visual Similarity Exacerbates the Moses Illusion for Semantically Similar Celebrities

ERIC Educational Resources Information Center

Davis, Danielle K.; Abrams, Lise

2016-01-01

When people read questions like "How many animals of each kind did Moses take on the ark?", many mistakenly answer "2" despite knowing that Noah sailed the ark. This "Moses illusion" occurs when names share semantic features. Two experiments examined whether shared "visual" concepts (facial features)…

Construction of Nitrogen-Doped Carbon-Coated MoSe2 Microspheres with Enhanced Performance for Lithium Storage.

PubMed

Tang, Wangjia; Xie, Dong; Shen, Tong; Wang, Xiuli; Wang, Donghuang; Zhang, Xuqing; Xia, Xinhui; Wu, Jianbo; Tu, Jiangping

2017-09-18

Exploring advanced anode materials with highly reversible capacity have gained great interests for large-scale lithium storage. A facile two-step method is developed to synthesize nitrogen-doped carbon coated MoSe 2 microspheres via hydrothermal plus thermal polymerization. The MoSe 2 microspheres composed of interconnected nanoflakes are homogeneously coated by a thin nitrogen-doped carbon (N-C) layer. As an anode for lithium ion batteries, the MoSe 2 /N-C composite shows better reversibility, smaller polarization, and higher electrochemical reactivity as compared to the unmodified MoSe 2 microspheres. The MoSe 2 /N-C electrode delivers a high specific capacity of 698 mAh g -1 after 100 cycles at a current density of 100 mA g -1 and good high rate performance (471 mAh g -1 at a high current density of 2000 mA g -1 ). The improved electrochemical performance is attributed to the conductive N-C coating and hierarchical microsphere structure with fast ion/electron transfer characteristics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Few-layered MoSe2 nanosheets as an advanced electrode material for supercapacitors.

PubMed

Balasingam, Suresh Kannan; Lee, Jae Sung; Jun, Yongseok

2015-09-21

We report the synthesis of few-layered MoSe2 nanosheets using a facile hydrothermal method and their electrochemical charge storage behavior. A systematic study of the structure and morphology of the as-synthesized MoSe2 nanosheets was performed. The downward peak shift in the Raman spectrum and the high-resolution transmission electron microscopy images confirmed the formation of few-layered nanosheets. The electrochemical energy-storage behavior of MoSe2 nanosheets was also investigated for supercapacitor applications in a symmetric cell configuration. The MoSe2 nanosheet electrode exhibited a maximum specific capacitance of 198.9 F g(-1) and the symmetric device showed 49.7 F g(-1) at a scan rate of 2 mV s(-1). A capacitance retention of approximately 75% was observed even after 10 000 cycles at a high charge-discharge current density of 5 A g(-1). The two-dimensional MoSe2 nanosheets exhibited a high specific capacitance and good cyclic stability, which makes it a promising electrode material for supercapacitor applications.

Preparation of 2D MoSe2/PEDOT:PSS composite and its thermoelectric properties

NASA Astrophysics Data System (ADS)

Li, Xia; Liu, Congcong; Wang, Tongzhou; Wang, Wenfang; Wang, Xiaodong; Jiang, Qinglin; Jiang, Fengxing; Xu, Jingkun

2017-11-01

Nowadays, inorganic/polymer composites have attracted significant interest in thermoelectric field, since the composite materials usually achieve their respective advantages complementary to each other. In this work, molybdenum diselenide (MoSe2) was synthesized by a facile hydrothermal method. Solution processible two-dimensional (2D) MoSe2 nanosheets (NSs) were successfully obtained using dimethylsulfoxide (DMSO) solvent or lithium intercalation procedure. Combined with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), MoSe2/PEDOT:PSS composite thin films were fabricated by direct vacuum-filtration method. Thermoelectric properties of composite thin films were investigated systematically and found that 2D MoSe2 NSs and PEDOT:PSS have the synergistic effect on improving thermoelectric properties. The maximum power factor was calculated to be 48.6 µW m-1 K-2 with 5 wt% 2D MoSe2 NSs embedding into PEDOT:PSS matrix, which is almost 69% higher than that of pure PEDOT:PSS. These results demonstrate that 2D inorganic/polymer composite method is one of promising strategies to get high-performance polymer-based thermoelectric composites.

Large-area and highly crystalline MoSe2 for optical modulator

NASA Astrophysics Data System (ADS)

Yin, Jinde; Chen, Hao; Lu, Wei; Liu, Mengli; Li, Irene Ling; Zhang, Min; Zhang, Wenfei; Wang, Jinzhang; Xu, Zihan; Yan, Peiguang; Liu, Wenjun; Ruan, Shuangchen

2017-12-01

Transition metal dichalcogenides (TMDs) have been successfully used as broadband optical modulator materials for pulsed fiber laser systems. However, the nonlinear optical absorptions of exfoliated TMDs are strongly limited by their nanoflakes morphology with uncontrollable lateral size and thickness. In this work, we provide an effective method to fully explore the nonlinear optical properties of MoSe2. Large-area and high quality lattice MoSe2 grown by chemical vapor deposition method was adopted as an optical modulator for the first time. The large-area MoSe2 shows excellent nonlinear optical absorption with a large modulation depth of 21.7% and small saturable intensity of 9.4 MW cm-2. After incorporating the MoSe2 optical modulator into fiber laser cavity as a saturable absorber, a highly stable Q-switching operation with single pulse energy of 224 nJ is achieved. The large-area MoSe2 possessing superior nonlinear optical properties compared to exfoliated nanoflakes affords possibility for the larger-area two-dimensional materials family as high performance optical devices.

MOSES: a Symbiosis Between the Lagos Ciência Viva Science Centre and a Research Project from the University of the Algarve

NASA Astrophysics Data System (ADS)

Leote, Catarina; Moura, Delminda; Azevedo Rodrigues, Luis

2017-04-01

Geoscience education is key for the understanding of our home, the planet Earth. The Lagos Ciência Viva Science Centre (CCVL) in Portugal develops various geoscience activities including astronomy sessions, geology, paleontology and oceanography field trips, complementary primary school classes, seminars and numerous workshops for a public ranging from pre-schoolers to seniors . Our experience in geoscience communication and informal education also includes a formal partnership with a research centre from the University of the Algarve, the CIMA - Centre for Marine and Environmental Research, through the project MOSES, which focuses on sand transport along crenulated coasts. Based on the project goals, methods and results, the CCVL team designed a communication and outreach plan including a seminar, a field trip and a workshop, to alert for the subjects of coastal erosion and management, both highly relevant in the Algarve. This partnership was highly beneficial for both parts as it facilitated the communication of a scientific project to the public, while the CCVL had the opportunity to update and expand its educational offer. This type of interaction between universities/research institutes and science centres/museums allows scientists to focus on their research work, reducing their need to invest in communication, and provides good and updated scientific contents to science communicators, ensuring a direct channel between scientific research and the public.

Molecular Optical Simulation Environment (MOSE): A Platform for the Simulation of Light Propagation in Turbid Media

PubMed Central

Ren, Shenghan; Chen, Xueli; Wang, Hailong; Qu, Xiaochao; Wang, Ge; Liang, Jimin; Tian, Jie

2013-01-01

The study of light propagation in turbid media has attracted extensive attention in the field of biomedical optical molecular imaging. In this paper, we present a software platform for the simulation of light propagation in turbid media named the “Molecular Optical Simulation Environment (MOSE)”. Based on the gold standard of the Monte Carlo method, MOSE simulates light propagation both in tissues with complicated structures and through free-space. In particular, MOSE synthesizes realistic data for bioluminescence tomography (BLT), fluorescence molecular tomography (FMT), and diffuse optical tomography (DOT). The user-friendly interface and powerful visualization tools facilitate data analysis and system evaluation. As a major measure for resource sharing and reproducible research, MOSE aims to provide freeware for research and educational institutions, which can be downloaded at http://www.mosetm.net. PMID:23577215

Electron radiation damage mechanisms in 2D MoSe2

NASA Astrophysics Data System (ADS)

Lehnert, T.; Lehtinen, O.; Algara-Siller, G.; Kaiser, U.

2017-01-01

The contributions of different damage mechanisms in single-layer MoSe2 were studied by investigating different MoSe2/graphene heterostructures by the aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) at 80 keV. The damage cross-sections were determined by direct counting of atoms in the AC-HRTEM images. The contributions of damage mechanisms such as knock-on damage or ionization effects were estimated by comparing the damage rates in different heterostructure configurations, similarly to what has been earlier done with MoS2. The behaviour of MoSe2 was found to be nearly identical to that of MoS2, which is an unexpected result, as the knock-on mechanism should be suppressed in MoSe2 due to the high mass of Se, as compared to S.

Novel MoSe2 hierarchical microspheres for applications in visible-light-driven advanced oxidation processes.

PubMed

Dai, Chu; Qing, Enping; Li, Yong; Zhou, Zhaoxin; Yang, Chao; Tian, Xike; Wang, Yanxin

2015-12-21

Advanced oxidation processes as a green technology have been adopted by combining the semiconductor catalyst MoSe2 with H2O2 under visible radiation. And novel three-dimensional self-assembled molybdenum diselenide (MoSe2) hierarchical microspheres from nanosheets were produced by using organic, selenium cyanoacetic acid sodium (NCSeCH2COONa) as the source of Se. The obtained products possess good crystallinity and present hierarchical structures with the average diameter of 1 μm. The band gap of MoSe2 microspheres is 1.68 eV and they present excellent photocatalytic activity under visible light irradiation in the MoSe2-H2O2 system. This effective photocatalytic mechanism was investigated in this study and can be attributed to visible-light-driven advanced oxidation processes.

CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors.

PubMed

Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

2014-08-07

Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ∼ 1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ∼ 60 ms and a good photoresponsivity of ∼ 13 mA/W (using a 532 nm laser at an intensity of 1 mW mm(-2) and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications.

Ferroelectric FET for nonvolatile memory application with two-dimensional MoSe2 channels

NASA Astrophysics Data System (ADS)

Wang, Xudong; Liu, Chunsen; Chen, Yan; Wu, Guangjian; Yan, Xiao; Huang, Hai; Wang, Peng; Tian, Bobo; Hong, Zhenchen; Wang, Yutao; Sun, Shuo; Shen, Hong; Lin, Tie; Hu, Weida; Tang, Minghua; Zhou, Peng; Wang, Jianlu; Sun, Jinglan; Meng, Xiangjian; Chu, Junhao; Li, Zheng

2017-06-01

Graphene and other two-dimensional materials have received considerable attention regarding their potential applications in nano-electronics. Here, we report top-gate nonvolatile memory field-effect transistors (FETs) with different layers of MoSe2 nanosheets channel gated by ferroelectric film. The conventional gate dielectric of FETs was replaced by a ferroelectric thin film that provides a ferroelectric polarization electric field, and therefore defined as an Fe-FET where the poly (vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) was used as the gate dielectric. Among the devices with MoSe2 channels of different thicknesses, the device with a single layer of MoSe2 exhibited a large hysteresis of electronic transport with an over 105 write/erase ratio, and displayed excellent retention and endurance performance. The possible mechanism of the device’s good properties was qualitatively analyzed using band theory. Additionally, a comprehensive study comparing the memory properties of MoSe2 channels of different thicknesses is presented. Increasing the numbers of MoSe2 layers was found to cause a reduced memory window. However, MoSe2 thickness of 5 nm yielded a write/erase ratio of more than 103. The results indicate that, based on a Fe-FET structure, the combination of two-dimensional semiconductors and organic ferroelectric gate dielectrics shows good promise for future applications in nonvolatile ferroelectric memory.

"Who Am I?": The Biblical Moses as a Metaphor for Teaching

ERIC Educational Resources Information Center

Gravett, Emily O.

2015-01-01

This essay presents Moses, the protagonist of the biblical books of Exodus and Deuteronomy in the Hebrew Bible, as a playful but generative metaphor for current teaching practices and experiences in higher education, including my own. Among numerous similarities (such as the fact that Moses, other teachers, and I are all bound by context), the…

Black Women's Faculty Voices in New Mexico: Invisible Assets Silent No More

ERIC Educational Resources Information Center

Woodley, Xeturah Monique

2014-01-01

There continues to exist a lack of Black women faculty at institutions of higher education (Moses, 1989; Collins, 1991; Gregory, 2001). Although we can see an increase in the number of research projects focused on Black women faculty there still remains a significant gap in the research (Glover, 2006; Foster-Williamson, 2002; Thomas &…

JPRS Report, Science & Technology, Europe & Latin America

DTIC Science & Technology

1987-08-12

there is significant international interest in this today. Going beyond the original applications the thermoluminescent dosimeters ( TLD ) developed...manufacturing; --Applications in the health and teaching sectors; —Correspondence management; -- Electronic mail. The competitive advantages of the multimedia...objective of the MOSES project is to make the multimedia electronic documentation system much more powerful than its paper counterpart. To achieve

Highly Crystalline CVD-grown Multilayer MoSe2 Thin Film Transistor for Fast Photodetector

PubMed Central

Jung, Chulseung; Kim, Seung Min; Moon, Hyunseong; Han, Gyuchull; Kwon, Junyeon; Hong, Young Ki; Omkaram, Inturu; Yoon, Youngki; Kim, Sunkook; Park, Jozeph

2015-01-01

Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm2/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τrise ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications. PMID:26477744

Layered MoSe2/Bi2WO6 composite with P-N heterojunctions as a promising visible-light induced photocatalyst

NASA Astrophysics Data System (ADS)

Xie, Taiping; Liu, Yue; Wang, Haiqiang; Wu, Zhongbiao

2018-06-01

In this paper, layered MoSe2/Bi2WO6 composites were fabricated by a simple bath sonication method for photocatalytic applications. Their photocatalytic performances were then investigated via the photocatalytic oxidation of gaseous toluene under visible-light irradiation. As a result, 1.5%-MoSe2/Bi2WO6 catalyst showed the highest activity with a degradation rate of nearly 80% during three-hour visible-light irradiation. The k value determined of 1.5%-MoSe2/Bi2WO6 was approximately 6 times higher than that of pure Bi2WO6 and 7 times higher compared with pure MoSe2. After a series of characterizations, it was concluded that the p-n heterojunctions of MoSe2/Bi2WO6 composites with strong interlayer interactions could effectively prolong the life time of photoinduced electron-hole pairs. And both the contents of surface superoxide and hydroxyl radicals were thereby increased, benefitting the photocatalytic process. Furthermore, the hydroxyl radicals and holes were found to be the major active species. This work provided a way to design photocatalyst with enhanced visible-light driven photoactivity toward indoor air pollutants purification.

New insights into the Mo/Cu(In,Ga)Se2 interface in thin film solar cells: Formation and properties of the MoSe2 interfacial layer.

PubMed

Klinkert, T; Theys, B; Patriarche, G; Jubault, M; Donsanti, F; Guillemoles, J-F; Lincot, D

2016-10-21

Being at the origin of an ohmic contact, the MoSe 2 interfacial layer at the Mo/Cu(In,Ga)Se 2 interface in CIGS (Cu(In,Ga)Se 2 and related compounds) based solar cells has allowed for very high light-to-electricity conversion efficiencies up to 22.3%. This article gives new insights into the formation and the structural properties of this interfacial layer. Different selenization-steps of a Mo covered glass substrate prior to the CIGS deposition by co-evaporation led to MoSe 2 interfacial layers with varying thickness and orientation, as observed by x-ray diffraction and atomic resolution transmission electron microscopy. A novel model based on the anisotropy of the Se diffusion coefficient in MoSe 2 is proposed to explain the results. While the series resistance of finished CIGS solar cells is found to correlate with the MoSe 2 orientation, the adhesion forces between the CIGS absorber layer and the Mo substrate stay constant. Their counter-intuitive non-correlation with the configuration of the MoSe 2 interfacial layer is discussed and related to work from the literature.

Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells

NASA Astrophysics Data System (ADS)

Yuwen, Lihui; Zhou, Jiajia; Zhang, Yuqian; Zhang, Qi; Shan, Jingyang; Luo, Zhimin; Weng, Lixing; Teng, Zhaogang; Wang, Lianhui

2016-01-01

Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation. Electronic supplementary information (ESI) available: Characterization, size distribution and EDS spectrum of MoSe2 NDs, calculation of the extinction coefficient and photothermal conversion efficiency of MoSe2 NDs. See DOI: 10.1039/c5nr08166a

Penstock leakage at the Robert Moses Niagara Power Plant - Investigation, design, and construction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumont, M.F.; Baker, C.H.; Broderick, W.

1995-12-31

This paper describes an investigation of observed penstock leakage and related gallery flooding at the Robert Moses Niagara Power Plant, in Lewiston, New York; engineering design of alternative remediation measures; test grouting of a dewatered penstock in 1991; and the subsequent grouting of the remaining twelve penstocks. The Robert Moses Niagara Power Plant is the lower part of the Niagara Pumped Storage Project, which is owned and operated by the New York Power Authority. Water diverted some 4 miles (6.4 km) upstream of the plant is passed through 13 individual penstocks 28 ft (8.5 m) in diameter to a powermore » plant on the right bank of the Niagara River. The net head at the plant is 300 ft (91.4 m), and the hydraulic capacity is about 91,000 cfs (2,575 m{sup 3}/s). The total installed capacity is about 2,000 MW. Since completion of construction in 1962 there had been recurring problems with flooding of the floors at the upper intake galleries. This was particularly noticeable during periods of heavy rainfall when the existing storm drains were close to their design capacity. The paper presents details of the investigations, including penstock inspection, methods of flow measurement and analysis, design criteria for the grout selected, details of the drilling and grout placement, and the anticipated long-term performance of the grout in service.« less

Fe/Co doped molybdenum diselenide: a promising two-dimensional intermediate-band photovoltaic material.

PubMed

Zhang, Jiajia; He, Haiyan; Pan, Bicai

2015-05-15

An intermediate-band (IB) photovoltaic material is an important candidate in developing the new-generation solar cell. In this paper, we propose that the Fe-doped or the Co-doped MoSe2 just meets the required features in IB photovoltaic materials. Our calculations demonstrate that when the concentration of the doped element reaches 11.11%, the doped MoSe2 shows a high absorptivity for both infrared and visible light, where the photovoltaic efficiency of the doped MoSe2 is as high as 56%, approaching the upper limit of photovoltaic efficiency of IB materials. So, the Fe- or Co-doped MoSe2 is a promising two-dimensional photovoltaic material.

Achieving tunable doping of MoSe2 based devices using GO@MoSe2 heterostructure

NASA Astrophysics Data System (ADS)

Maji, Tuhin Kumar; Tiwary, Krishna Kanhaiya; Karmakar, Debjani

2017-05-01

Doping nature of MoSe2, one of the promising Graphene analogous device material, can be tuned by controlling the concentration of functional groups in Graphene oxide (GO)@MoSe2 heterostructure. In this study, by first-principles simulation, we have observed that GO can be used as a carrier injection layer for MoSe2, where n or p type carriers are introduced within MoSe2 layer depending on the type and concentration of functional moieties in it. Both n and p-type Schottky barrier height modulations are investigated for different modeled configurations of the heterostructure. This combinatorial heterostructure can be a promising material for future electronic device application.

Fullerene-like MoSe2 nanoparticles-embedded CNT balls with excellent structural stability for highly reversible sodium-ion storage

NASA Astrophysics Data System (ADS)

Choi, Seung Ho; Kang, Yun Chan

2016-02-01

Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls.Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250th discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g-1, respectively, at a high current density of 1.0 A g-1, and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10th discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g-1 at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07733h

Memory and the Moses illusion: failures to detect contradictions with stored knowledge yield negative memorial consequences.

PubMed

Bottoms, Hayden C; Eslick, Andrea N; Marsh, Elizabeth J

2010-08-01

Although contradictions with stored knowledge are common in daily life, people often fail to notice them. For example, in the Moses illusion, participants fail to notice errors in questions such as "How many animals of each kind did Moses take on the Ark?" despite later showing knowledge that the Biblical reference is to Noah, not Moses. We examined whether error prevalence affected participants' ability to detect distortions in questions, and whether this in turn had memorial consequences. Many of the errors were overlooked, but participants were better able to catch them when they were more common. More generally, the failure to detect errors had negative memorial consequences, increasing the likelihood that the errors were used to answer later general knowledge questions. Methodological implications of this finding are discussed, as it suggests that typical analyses likely underestimate the size of the Moses illusion. Overall, answering distorted questions can yield errors in the knowledge base; most importantly, prior knowledge does not protect against these negative memorial consequences.

MOSES: a modular sensor electronics system for space science and commercial applications

NASA Astrophysics Data System (ADS)

Michaelis, Harald; Behnke, Thomas; Tschentscher, Matthias; Mottola, Stefano; Neukum, Gerhard

1999-10-01

The camera group of the DLR--Institute of Space Sensor Technology and Planetary Exploration is developing imaging instruments for scientific and space applications. One example is the ROLIS imaging system of the ESA scientific space mission `Rosetta', which consists of a descent/downlooking and a close-up imager. Both are parts of the Rosetta-Lander payload and will operate in the extreme environment of a cometary nucleus. The Rosetta Lander Imaging System (ROLIS) will introduce a new concept for the sensor electronics, which is referred to as MOSES (Modula Sensor Electronics System). MOSES is a 3D miniaturized CCD- sensor-electronics which is based on single modules. Each of the modules has some flexibility and enables a simple adaptation to specific application requirements. MOSES is mainly designed for space applications where high performance and high reliability are required. This concept, however, can also be used in other science or commercial applications. This paper describes the concept of MOSES, its characteristics, performance and applications.

Construction of multifunctional MoSe2 hybrid towards the simultaneous improvements in fire safety and mechanical property of polymer.

PubMed

Wang, Junling; Ma, Chao; Mu, Xiaowei; Cai, Wei; Liu, Longxiang; Zhou, Xia; Hu, Weizhao; Hu, Yuan

2018-06-15

Organic modification of MoSe 2 sheets is firstly achieved by Atherton-Todd reaction, aiming at the acquisition of multifunctional MoSe 2 hybrid. Simultaneous enhancements in fire safety and mechanical property of thermalplastic polyurethane (TPU) are obtained with the presence of this hybrid. Strong interfacial interactions between the functionalized MoSe 2 sheets and TPU can be obtained, making more efficient load transfer from the weak polymer chains to the robust sheets. Besides, more coherent barrier network may be formed in polymer matrix, restraining the diffusion of decomposed fragments and reducing the supply for combustion fuel. Consequently, the decreases in heat release are observed for polymer composites. Notably, the releases of toxic gases, such as HCN and CO, are also suppressed by this barrier network, resulting in the reductions in fire toxicity. This work may open a new door for the functionalization of MoSe 2 sheets and evoke significant developments in its promising applications. Copyright © 2018. Published by Elsevier B.V.

Integrated MoSe2 with n+p-Si photocathodes for solar water splitting with high efficiency and stability

NASA Astrophysics Data System (ADS)

Huang, Guanping; Mao, Jie; Fan, Ronglei; Yin, Zhihao; Wu, Xi; Jie, Jiansheng; Kang, Zhenhui; Shen, Mingrong

2018-01-01

Many earth-abundant transition metal dichalcogenides (TMDs) have been employed as catalysts for H2 evolution reaction (HER); however, their impactful integration onto photocathodes for photoelectrochemical (PEC) HER is less developed. In this study, we directly sputtered a MoSe2 catalyst onto an n+p-Si photocathode for efficient and stable PEC-HER. An onset potential of 0.4 V vs. RHE, a saturated photocurrent of 29.3 mA/cm2, a fill factor of 0.32, and an energy conversion efficiency of 3.8% were obtained under 100 mA/cm2 Xe lamp illumination. Such superior PEC properties were ascribed to the nearly vertically standing two dimensional MoSe2 rough surface layer and the sharp interface between Si and MoSe2 with small charge transfer resistance. The balance between the reflectivity of the electrode surface and the absorptivity of MoSe2 was also discussed. In addition, the MoSe2 layer can protect the n+p-Si photocathode with a 120 h stability due to its initial growth on Si with high flatness and compactness. This study provides a path to the effective and scalable growth of TMDs onto the Si photocathode aiming for high efficiency and stability.

Fullerene-like MoSe2 nanoparticles-embedded CNT balls with excellent structural stability for highly reversible sodium-ion storage.

PubMed

Choi, Seung Ho; Kang, Yun Chan

2016-02-21

Three-dimensional (3D) porous-structured carbon nanotube (CNT) balls embedded with fullerene-like MoSe2 nanocrystals were successfully prepared by the spray pyrolysis process and subsequent selenization process. The MoO2-CNT composite balls prepared by spray pyrolysis transformed into the fullerene-like MoSe2/CNT (F-MoSe2/CNT) composite balls by the selenization process. The F-MoSe2/CNT composite balls exhibited superior sodium-ion storage properties to bare MoSe2 and MoSe2/CNT with a filled structure (N-MoSe2/CNT), both of which were prepared as comparison samples. The 250(th) discharge capacities of bare MoSe2, N-MoSe2/CNT composite balls, and F-MoSe2/CNT composite balls were 144, 200, and 296 mA h g(-1), respectively, at a high current density of 1.0 A g(-1), and their capacity retentions measured from the second cycle were 37%, 66%, and 83%, respectively. The 10(th) discharge capacities of the F-MoSe2/CNT composite balls were 382, 346, 310, 280, and 255 mA h g(-1) at current densities of 0.2, 0.5, 1.5, 3.0, and 5.0 A g(-1), respectively. The synergetic effect of the fullerene-like MoSe2 nanocrystals with ultrafine sizes and the CNT balls with a tangled and 3D porous structure and high electrical conductivity resulted in excellent sodium-ion storage properties of the F-MoSe2/CNT composite balls.

Sediment Loading from Crab Creek and Other Sources to Moses Lake, Washington, 2007 and 2008

USGS Publications Warehouse

Magirl, Christopher S.; Cox, Stephen E.; Mastin, Mark C.; Huffman, Raegan L.

2010-01-01

The average sediment-accumulation rate on the bed of Moses Lake since 1980, based on the identification of Mount St. Helens ash in lakebed cores, was 0.24 inches per year. Summed over the lake surface area, the average sediment-accumulation rate on the lakebed is 190,000 tons per year. Based on USGS stream-gaging station data, the average annual sediment load to Moses Lake from Crab Creek was 32,000 tons per year between 1943 and 2008; the post Mount St. Helens eruption annual load from Crab Creek was calculated to be 13,000 tons per year. The total mass input from Crab Creek and other fluvially derived sediment sources since 1980 has been about 20,000 tons per year. Eolian sediment loading to Moses Lake was about 50,000 tons per year before irrigation and land-use development largely stabilized the Moses Lake dune field. Currently, eolian input to the lake is less than 2,000 tons per year. Considering all sediment sources to the lake, most (from 80 to 90 percent) of post-1980 lakebed-sediment accumulation is from autochthonous, or locally formed, mineral matter, including diatom frustuals and carbonate shells, derived from biogenic production in phytoplankton and zooplankton. Suspended-sediment samples collected from Crab Creek and similar nearby waterways in 2007 and 2008 combined with other USGS data from the region indicated that a proposed Bureau of Reclamation supplemental feed of as much as 650 cubic feet per second through Crab Creek might initially contain a sediment load of as much as 1,500 tons per day. With time, however, this sediment load would decrease to about 10 tons per day in the sediment-supply-limited creek as available sediment in the channel is depleted. Sediment loads in the supplemental feed ultimately would be similar to loads in other bypass canals near Moses Lake. Considering the hydrology and geomorphology of the creek over multiple years, there is little evidence that the proposed supplemental feed would substantially increase the overall sediment load from Crab Creek to Moses Lake relative to natural, background conditions. Because Moses Lake is relatively shallow and subject to significant wind-driven circulation currents, mixing also would redistribute some of the fluvial sediment load deposited from Crab Creek throughout Parker Horn and the rest of Moses Lake, further mitigating the local effect of Crab Creek sedimentation near the City of Moses Lake.

Two-step growth of two-dimensional WSe 2/MoSe 2 heterostructures

DOE PAGES

Gong, Yongji; Lei, Sidong; Lou, Jun; ...

2015-08-03

Two dimensional (2D) materials have attracted great attention due to their unique properties and atomic thickness. Although various 2D materials have been successfully synthesized with different optical and electrical properties, a strategy for fabricating 2D heterostructures must be developed in order to construct more complicated devices for practical applications. Here we demonstrate for the first time a two-step chemical vapor deposition (CVD) method for growing transition-metal dichalcogenide (TMD) heterostructures, where MoSe 2 was synthesized first and followed by an epitaxial growth of WSe 2 on the edge and on the top surface of MoSe 2. Compared to previously reported one-stepmore » growth methods, this two-step growth has the capability of spatial and size control of each 2D component, leading to much larger (up to 169 μm) heterostructure size, and cross-contamination can be effectively minimized. Furthermore, this two-step growth produces well-defined 2H and 3R stacking in the WSe 2/MoSe 2 bilayer regions and much sharper in-plane interfaces than the previously reported MoSe 2/WSe 2 heterojunctions obtained from one-step growth methods. The resultant heterostructures with WSe 2/MoSe 2 bilayer and the exposed MoSe 2 monolayer display rectification characteristics of a p-n junction, as revealed by optoelectronic tests, and an internal quantum efficiency of 91% when functioning as a photodetector. As a result, a photovoltaic effect without any external gates was observed, showing incident photon to converted electron (IPCE) efficiencies of approximately 0.12%, providing application potential in electronics and energy harvesting.« less

Correlation of Soot Formation in Turbojet Engines and in Laboratory Flames.

DTIC Science & Technology

1981-02-01

measured dependent variables were the flame radiation in the primary combustion zone and tile combus- tor liner temperature. Naegeli and Moses...Can-Type Turbine Combustion Systems," AFAPL- TR-79-2072, General Motors Corporation, April 1980. 9. Moses, C.A. and Naegeli , D.W., "Fuel Property...Effects on Combustor Perfor- mance," MED 114, Southwest Research Institute, March 1980. 10. Moses, C.A. and Naegeli , D.W., "Fuel Property Effects on

Interstitial Mo-Assisted Photovoltaic Effect in Multilayer MoSe2 Phototransistors.

PubMed

Kim, Sunkook; Maassen, Jesse; Lee, Jiyoul; Kim, Seung Min; Han, Gyuchull; Kwon, Junyeon; Hong, Seongin; Park, Jozeph; Liu, Na; Park, Yun Chang; Omkaram, Inturu; Rhyee, Jong-Soo; Hong, Young Ki; Yoon, Youngki

2018-03-01

Thin-film transistors (TFTs) based on multilayer molybdenum diselenide (MoSe 2 ) synthesized by modified atmospheric pressure chemical vapor deposition (APCVD) exhibit outstanding photoresponsivity (103.1 A W -1 ), while it is generally believed that optical response of multilayer transition metal dichalcogenides (TMDs) is significantly limited due to their indirect bandgap and inefficient photoexcitation process. Here, the fundamental origin of such a high photoresponsivity in the synthesized multilayer MoSe 2 TFTs is sought. A unique structural characteristic of the APCVD-grown MoSe 2 is observed, in which interstitial Mo atoms exist between basal planes, unlike usual 2H phase TMDs. Density functional theory calculations and photoinduced transfer characteristics reveal that such interstitial Mo atoms form photoreactive electronic states in the bandgap. Models indicate that huge photoamplification is attributed to trapped holes in subgap states, resulting in a significant photovoltaic effect. In this study, the fundamental origin of high responsivity with synthetic MoSe 2 phototransistors is identified, suggesting a novel route to high-performance, multifunctional 2D material devices for future wearable sensor applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thiocarbamates from Moringa oleifera Seeds Bioactive against Virulent and Multidrug-Resistant Vibrio Species

PubMed Central

de Sousa, Oscarina Viana; Hofer, Ernesto; Mafezoli, Jair; Barbosa, Francisco Geraldo

2017-01-01

Prospect of antibacterial agents may provide an alternative therapy for diseases caused by multidrug-resistant bacteria. This study aimed to evaluate the in vitro bioactivity of Moringa oleifera seed extracts against 100 vibrios isolated from the marine shrimp Litopenaeus vannamei. Ethanol extracts at low (MOS-E) and hot (MOS-ES) temperature are shown to be bioactive against 92% and 90% of the strains, respectively. The most efficient Minimum Inhibitory Concentration (MIC) levels of MOS-E and MOS-ES against a high percentage of strains were 32 µg mL−1. Bioguided screening of bioactive compounds showed that the ethyl acetate fraction from both extracts was the only one that showed antibacterial activity. Vibriocidal substances, niazirine and niazimicine, were isolated from the aforementioned fraction through chromatographic fractionation. PMID:28770224

Non-polynomial extensions of solvable potentials à la Abraham-Moses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odake, Satoru; Sasaki, Ryu; Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan

2013-10-15

Abraham-Moses transformations, besides Darboux transformations, are well-known procedures to generate extensions of solvable potentials in one-dimensional quantum mechanics. Here we present the explicit forms of infinitely many seed solutions for adding eigenstates at arbitrary real energy through the Abraham-Moses transformations for typical solvable potentials, e.g., the radial oscillator, the Darboux-Pöschl-Teller, and some others. These seed solutions are simple generalisations of the virtual state wavefunctions, which are obtained from the eigenfunctions by discrete symmetries of the potentials. The virtual state wavefunctions have been an essential ingredient for constructing multi-indexed Laguerre and Jacobi polynomials through multiple Darboux-Crum transformations. In contrast to themore » Darboux transformations, the virtual state wavefunctions generate non-polynomial extensions of solvable potentials through the Abraham-Moses transformations.« less

02-NIF Dedication: Edward Moses

ScienceCinema

Edward Moses

2017-12-09

The National Ignition Facility, the world's largest laser system, was dedicated at a ceremony on May 29, 2009 at Lawrence Livermore National Laboratory. These are the remarks by NIF Director Edward Moses.

Autogenous Crack Control during Construction Phases of MOSE Venice Dams

NASA Astrophysics Data System (ADS)

Bertagnoli, Gabriele; Anerdi, Constanza; Malavisi, Marzia; Zoratto, Nadia

2017-10-01

The design of concrete structures exposed to severe environmental attack, like in marine environment, requires serious attention for concrete durability. Early age cracking due to autogenous deformations can be detrimental to the performance of tidal structures. The study of the structural effects of hydration heat and rheological behaviour of a set of huge concrete structures of the Mobile Venice Dams known with the MOSE acronym (Experimental Electromechanical Module) is presented in this paper. Together with other measures such as coastal reinforcement, the raising of quaysides, and the paving and improvement of the lagoon, MOSE is designed to protect Venice and the lagoon from tides of up to 3 meters. Construction began simultaneously in 2003 at all three lagoon inlets, and the project has been completed in 2014. Floods have caused damage since ancient times and have become more frequent and intense as a result of the combined effect of eustatism (a rise in sea level) and subsidence (a drop in land level) caused by natural and man-induced phenomena. Nowadays, towns and villages in the lagoon are about 23 cm lower with respect to the water level than at the beginning of the 1900s. Each year, floods can cause serious problems for the inhabitants as well as deterioration of architecture, urban structures and the ecosystem. Over the entire lagoon area, there is also a constant risk of a catastrophic event such as that of 4 November 1966, when a tide of 194 cm submerged Venice, Chioggia and the other built-up areas.

3. Photocopy of drawing (from Moses King, Philadelphia and Notable ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. Photocopy of drawing (from Moses King, Philadelphia and Notable Philadelphians, 1902) MAIN BUILDING WITH ADDITION - New York Mutual Life Insurance Company Building, 1001-1005 Chestnut Street, Philadelphia, Philadelphia County, PA

Broadband nonlinear optical response of monolayer MoSe2 under ultrafast excitation

NASA Astrophysics Data System (ADS)

Nie, Zhonghui; Trovatello, Chiara; Pogna, Eva A. A.; Dal Conte, Stefano; Miranda, Paulo B.; Kelleher, Edmund; Zhu, Chunhui; Turcu, Ion Crisitan Edmond; Xu, Yongbing; Liu, Kaihui; Cerullo, Giulio; Wang, Fengqiu

2018-01-01

Due to their strong light-matter interaction, monolayer transition metal dichalcogenides (TMDs) have proven to be promising candidates for nonlinear optics and optoelectronics. Here, we characterize the nonlinear absorption of chemical vapour deposition (CVD)-grown monolayer MoSe2 in the 720-810 nm wavelength range. Surprisingly, despite the presence of strong exciton resonances, monolayer MoSe2 exhibits a uniform modulation depth of ˜80 ± 3% and a saturation intensity of ˜2.5 ± 0.4 MW/cm2. In addition, pump-probe spectroscopy is performed to confirm the saturable absorption and reveal the photocarrier relaxation dynamics over hundreds of picoseconds. Our results unravel the unique broadband nonlinear absorptive behavior of monolayer MoSe2 under ultrafast excitation and highlight the potential of using monolayer TMDs as broadband ultrafast optical switches with customizable saturable absorption characteristics.

Dual-Native Vacancy Activated Basal Plane and Conductivity of MoSe2 with High-Efficiency Hydrogen Evolution Reaction.

PubMed

Gao, Daqiang; Xia, Baorui; Wang, Yanyan; Xiao, Wen; Xi, Pinxian; Xue, Desheng; Ding, Jun

2018-04-01

Although transition metal dichalcogenide MoSe 2 is recognized as one of the low-cost and efficient electrocatalysts for the hydrogen evolution reaction (HER), its thermodynamically stable basal plane and semiconducting property still hamper the electrocatalytic activity. Here, it is demonstrated that the basal plane and edges of 2H-MoSe 2 toward HER can be activated by introducing dual-native vacancy. The first-principle calculations indicate that both the Se and Mo vacancies together activate the electrocatalytic sites in the basal plane and edges of MoSe 2 with the optimal hydrogen adsorption free energy (ΔG H* ) of 0 eV. Experimentally, 2D MoSe 2 nanosheet arrays with a large amount of dual-native vacancies are fabricated as a catalytic working electrode, which possesses an overpotential of 126 mV at a current density of 100 mV cm -2 , a Tafel slope of 38 mV dec -1 , and an excellent long-term durability. The findings pave a rational pathway to trigger the activity of inert MoSe 2 toward HER and also can be extended to other layered dichalcogenide. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge Versus Energy Transfer in Atomically Thin Graphene-Transition Metal Dichalcogenide van der Waals Heterostructures

NASA Astrophysics Data System (ADS)

Froehlicher, Guillaume; Lorchat, Etienne; Berciaud, Stéphane

2018-01-01

Made from stacks of two-dimensional materials, van der Waals heterostructures exhibit unique light-matter interactions and are promising for novel optoelectronic devices. The performance of such devices is governed by near-field coupling through, e.g., interlayer charge and/or energy transfer. New concepts and experimental methodologies are needed to properly describe two-dimensional heterointerfaces. Here, we report an original study of interlayer charge and energy transfer in atomically thin metal-semiconductor [i.e., graphene-transition metal dichalcogenide (TMD, here molybdenum diselenide, MoSe2 )] heterostructures using a combination of microphotoluminescence and Raman scattering spectroscopies. The photoluminescence intensity in graphene /MoSe2 is quenched by more than 2 orders of magnitude and rises linearly with the incident photon flux, demonstrating a drastically shortened (about 1 ps) room-temperature MoSe2 exciton lifetime. Key complementary insights are provided from a comprehensive analysis of the graphene and MoSe2 Raman modes, which reveals net photoinduced electron transfer from MoSe2 to graphene and hole accumulation in MoSe2 . Remarkably, the steady-state Fermi energy of graphene saturates at 290 ±15 meV above the Dirac point. This reproducible behavior is observed both in ambient air and in vacuum and is discussed in terms of intrinsic factors (i.e., band offsets) and environmental effects. In this saturation regime, balanced photoinduced flows of electrons and holes may transfer to graphene, a mechanism that effectively leads to energy transfer. Using a broad range of incident photon fluxes and diverse environmental conditions, we find that the presence of net photoinduced charge transfer has no measurable impact on the near-unity photoluminescence quenching efficiency in graphene /MoSe2 . This absence of correlation strongly suggests that energy transfer to graphene (either in the form of electron exchange or dipole-dipole interaction) is the dominant interlayer coupling mechanism between atomically thin TMDs and graphene.

Electronic structure investigation of MoS2 and MoSe2 using angle-resolved photoemission spectroscopy and ab initio band structure studies.

PubMed

Mahatha, S K; Patel, K D; Menon, Krishnakumar S R

2012-11-28

Angle-resolved photoemission spectroscopy (ARPES) and ab initio band structure calculations have been used to study the detailed valence band structure of molybdenite, MoS(2) and MoSe(2). The experimental band structure obtained from ARPES has been found to be in good agreement with the theoretical calculations performed using the linear augmented plane wave (LAPW) method. In going from MoS(2) to MoSe(2), the dispersion of the valence bands decreases along both k(parallel) and k(perpendicular), revealing the increased two-dimensional character which is attributed to the increasing interlayer distance or c/a ratio in these compounds. The width of the valence band and the band gap are also found to decrease, whereas the valence band maxima shift towards the higher binding energy from MoS(2) to MoSe(2).

Large Excitonic Reflectivity of Monolayer MoSe2 Encapsulated in Hexagonal Boron Nitride

NASA Astrophysics Data System (ADS)

Scuri, Giovanni; Zhou, You; High, Alexander A.; Wild, Dominik S.; Shu, Chi; De Greve, Kristiaan; Jauregui, Luis A.; Taniguchi, Takashi; Watanabe, Kenji; Kim, Philip; Lukin, Mikhail D.; Park, Hongkun

2018-01-01

We demonstrate that a single layer of MoSe2 encapsulated by hexagonal boron nitride can act as an electrically switchable mirror at cryogenic temperatures, reflecting up to 85% of incident light at the excitonic resonance. This high reflectance is a direct consequence of the excellent coherence properties of excitons in this atomically thin semiconductor. We show that the MoSe2 monolayer exhibits power-and wavelength-dependent nonlinearities that stem from exciton-based lattice heating in the case of continuous-wave excitation and exciton-exciton interactions when fast, pulsed laser excitation is used.

Stacking orders induced direct band gap in bilayer MoSe2-WSe2 lateral heterostructures.

PubMed

Hu, Xiaohui; Kou, Liangzhi; Sun, Litao

2016-08-16

The direct band gap of monolayer semiconducting transition-metal dichalcogenides (STMDs) enables a host of new optical and electrical properties. However, bilayer STMDs are indirect band gap semiconductors, which limits its applicability for high-efficiency optoelectronic devices. Here, we report that the direct band gap can be achieved in bilayer MoSe2-WSe2 lateral heterostructures by alternating stacking orders. Specifically, when Se atoms from opposite layers are stacked directly on top of each other, AA and A'B stacked heterostructures show weaker interlayer coupling, larger interlayer distance and direct band gap. Whereas, when Se atoms from opposite layers are staggered, AA', AB and AB' stacked heterostructures exhibit stronger interlayer coupling, shorter interlayer distance and indirect band gap. Thus, the direct/indirect band gap can be controllable in bilayer MoSe2-WSe2 lateral heterostructures. In addition, the calculated sliding barriers indicate that the stacking orders of bilayer MoSe2-WSe2 lateral heterostructures can be easily formed by sliding one layer with respect to the other. The novel direct band gap in bilayer MoSe2-WSe2 lateral heterostructures provides possible application for high-efficiency optoelectronic devices. The results also show that the stacking order is an effective strategy to induce and tune the band gap of layered STMDs.

Activation of electrocatalytic properties of a-C films by doping with MoSe x clusters

NASA Astrophysics Data System (ADS)

Grigoriev, S. N.; Fominski, V. Y.; Romanov, R. I.; Volosova, M. A.; Fominski, D. V.

2017-12-01

Nanocomposite a-C(Mo/MoSe x ) thin films containing amorphous carbon matrix a-C, nano-Mo and MoSe x ≥2 clusters were obtained by pulsed laser co-deposition of carbon and MoSe2. The deposition was carried out at room temperature onto a graphite substrate. Atomic content of the MoSe x≥2 phase did not exceed 25%. The use of a buffer gas at a pressure of 10 Pa allowed to obtain the maximum Se/Mo ratio in the films and to increase the concentration of sp2-hybridized C atoms for high conductivity realization. The formation of MoSe x≥2 cluster inclusions was the essential factor for activation of hydrogen evolution reaction (HER) in 0.5 M H2SO4 aqueous solution. These clusters also promoted cathodic deposition of Pt nanoparticles on the surface of a-C(Mo/MoSe x ) in a H2SO4/KCl solution when a Pt anode was used as a source of Pt. Hybrid Pt/a-C(Mo/MoSe x ) thin-film coatings with a low Pt loading (~6 μg/cm2) exhibit excellent HER property, which noticeably exceeds that of relatively thick Pt coating prepared on a graphite substrate by pulsed laser deposition.

Tunable Free-Standing Core-Shell CNT@MoSe2 Anode for Lithium Storage.

PubMed

Yousaf, Muhammad; Wang, Yunsong; Chen, Yijun; Wang, Zhipeng; Aftab, Waseem; Mahmood, Asif; Wang, Wei; Guo, Shaojun; Han, Ray P S

2018-05-02

Heterogeneous nanostructuring of MoSe 2 over a carbon nanotube (CNT) sponge as a free-standing electrode not only brings higher performance but also eliminates the need for dead elements such as a binder, conductive carbon, and supportive current collectors. Further, the porous CNT sponge can be easily compacted via an intense densification of the active material MoSe 2 to produce an electrode with a high mass loading for a significantly improved areal capacity. In this work, we present a tunable coating of MoSe 2 on a CNT sponge to fabricate a core-shell MoSe 2 @CNT anode. The three-dimensional nanotubular sponge is synthesized via a solvothermal process, followed by thermal annealing to improve crystallization. Structural and morphological studies revealed that MoSe 2 grew as a layered structure ( d = 0.66 nm), where numbers of layers can be controlled to yield optimized results for Li + storage. We showed that the 10-layer core-shell CNT@MoSe 2 hybrid sponge delivered a discharge capacity of 820.5 mAh g -1 after 100 cycles at 100 mA g -1 with a high cyclic stability and rate capability. Further, an ex situ structural and morphological analysis revealed that ionic storage causes a phase change in MoSe 2 from a crystalline to a partial amorphous state for a continuous increase in the capacity with extended cycling. We believe that the strategy developed here will assist users to tune the electrode materials for future energy-storage devices, especially how the materials are changing with the passage of time and their effects on the device performance.

Exciton band structure in layered MoSe2: from a monolayer to the bulk limit.

PubMed

Arora, Ashish; Nogajewski, Karol; Molas, Maciej; Koperski, Maciej; Potemski, Marek

2015-12-28

We present the micro-photoluminescence (μPL) and micro-reflectance contrast (μRC) spectroscopy studies on thin films of MoSe(2) with layer thicknesses ranging from a monolayer (1L) up to 5L. The thickness dependent evolution of the ground and excited state excitonic transitions taking place at various points of the Brillouin zone is determined. Temperature activated energy shifts and linewidth broadenings of the excitonic resonances in 1L, 2L and 3L flakes are accounted for by using standard formalisms previously developed for semiconductors. A peculiar shape of the optical response of the ground state (A) exciton in monolayer MoSe(2) is tentatively attributed to the appearance of a Fano-type resonance. Rather trivial and clearly decaying PL spectra of monolayer MoSe(2) with temperature confirm that the ground state exciton in this material is optically bright in contrast to a dark exciton ground state in monolayer WSe(2).

Controllable Growth of Monolayer MoS2 and MoSe2 Crystals Using Three-temperature-zone Furnace

NASA Astrophysics Data System (ADS)

Zheng, Binjie; Chen, Yuanfu

2017-12-01

Monolayer molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) have attracted a great attention for their exceptional electronic and optoelectronic properties among the two dimensional family. However, controllable synthesis of monolayer crystals with high quality needs to be improved urgently. Here we demonstrate a chemical vapor deposition (CVD) growth of monolayer MoS2 and MoSe2 crystals using three-temperature-zone furnace. Systematical study of the effects of growth pressure, temperature and time on the thickness, morphology and grain size of crystals shows the good controllability. The photoluminescence (PL) characterizations indicate that the as-grown monolayer MoS2 and MoSe2 crystals possess excellent optical qualities with very small full-width-half-maximum (FWHM) of 96 me V and 57 me V, respectively. It is comparable to that of exfoliated monolayers and reveals their high crystal quality. It is promising that our strategy should be applicable for the growth of other transition metal dichalcogenides (TMDs) monolayer crystals.

Exciton band structure in layered MoSe2: from a monolayer to the bulk limit

NASA Astrophysics Data System (ADS)

Arora, Ashish; Nogajewski, Karol; Molas, Maciej; Koperski, Maciej; Potemski, Marek

2015-12-01

We present the micro-photoluminescence (μPL) and micro-reflectance contrast (μRC) spectroscopy studies on thin films of MoSe2 with layer thicknesses ranging from a monolayer (1L) up to 5L. The thickness dependent evolution of the ground and excited state excitonic transitions taking place at various points of the Brillouin zone is determined. Temperature activated energy shifts and linewidth broadenings of the excitonic resonances in 1L, 2L and 3L flakes are accounted for by using standard formalisms previously developed for semiconductors. A peculiar shape of the optical response of the ground state (A) exciton in monolayer MoSe2 is tentatively attributed to the appearance of a Fano-type resonance. Rather trivial and clearly decaying PL spectra of monolayer MoSe2 with temperature confirm that the ground state exciton in this material is optically bright in contrast to a dark exciton ground state in monolayer WSe2.

Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system

NASA Astrophysics Data System (ADS)

Simonelli, L.; Paris, E.; Wakita, T.; Marini, C.; Terashima, K.; Miao, X.; Olszewski, W.; Ramanan, N.; Heinis, D.; Kubozono, Y.; Yokoya, T.; Saini, N. L.

2017-12-01

We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE) of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

Structural Phase Transformation in Strained Monolayer MoWSe2 Alloy.

PubMed

Apte, Amey; Kochat, Vidya; Rajak, Pankaj; Krishnamoorthy, Aravind; Manimunda, Praveena; Hachtel, Jordan A; Idrobo, Juan Carlos; Syed Amanulla, Syed Asif; Vashishta, Priya; Nakano, Aiichiro; Kalia, Rajiv K; Tiwary, Chandra Sekhar; Ajayan, Pulickel M

2018-04-24

Two-dimensional (2D) materials exhibit different mechanical properties from their bulk counterparts owing to their monolayer atomic thickness. Here, we have examined the mechanical behavior of 2D molybdenum tungsten diselenide (MoWSe 2 ) precipitation alloy grown using chemical vapor deposition and composed of numerous nanoscopic MoSe 2 and WSe 2 regions. Applying a bending strain blue-shifted the MoSe 2 and WSe 2 A 1g Raman modes with the stress concentrated near the precipitate interfaces predominantly affecting the WSe 2 modes. In situ local Raman measurements suggested that the crack propagated primarily thorough MoSe 2 -rich regions in the monolayer alloy. Molecular dynamics (MD) simulations were performed to study crack propagation in an MoSe 2 monolayer containing nanoscopic WSe 2 regions akin to the experiment. Raman spectra calculated from MD trajectories of crack propagation confirmed the emergence of intermediate peaks in the strained monolayer alloy, mirroring experimental results. The simulations revealed that the stress buildup around the crack tip caused an irreversible structural transformation from the 2H to 1T phase both in the MoSe 2 matrix and WSe 2 patches. This was corroborated by high-angle annular dark-field images. Crack branching and subsequent healing of a crack branch were also observed in WSe 2 , indicating the increased toughness and crack propagation resistance of the alloyed 2D MoWSe 2 over the unalloyed counterparts.

Interlayer excitons in MoSe2/WSe2 heterostructures from first principles

NASA Astrophysics Data System (ADS)

Gillen, Roland; Maultzsch, Janina

2018-04-01

Based on ab initio theoretical calculations of the optical spectra of vertical heterostructures of MoSe2 (or MoS2) and WSe2 sheets, we reveal two spin-orbit-split Rydberg series of excitonic states below the A excitons of MoSe2 and WSe2 with a significant binding energy on the order of 250 meV for the first excitons in the series. At the same time, we predict from accurate many-body G0W0 calculations that crystallographically aligned MoSe2/WSe2 heterostructures exhibit an indirect fundamental band gap. Due to the type-II nature of the MoSe2/WSe2 heterostructure, the indirect transition and the exciton Rydberg series corresponding to a direct transition exhibit a distinct interlayer nature with spatial charge separation of the coupled electrons and holes. Our calculations confirm the recent experimental observation of a doublet nature of the long-lived states in photoluminescence spectra of Mo X2/W Y2 heterostructures, and we attribute these two contributions to momentum-direct interlayer excitons at the K point of the hexagonal Brillouin zone and to momentum-indirect excitons at the indirect fundamental band gap. Our calculations further suggest a noticeable effect of stacking order on the electronic band gaps and on the peak energies of the interlayer excitons and their oscillation strengths.

Social withdrawal of persons with vascular dementia associated with disturbance of basic daily activities, apathy, and impaired social judgment.

PubMed

Honda, Yukiko; Meguro, Kenichi; Meguro, Mitsue; Akanuma, Kyoko

2013-01-01

Patients with vascular dementia (VaD) are often isolated, withdrawn from society because of negative symptoms and functional disabilities. The aim of this study was to detect factors associated with social withdrawal in patients with VaD. The participants were 36 institutionalized patients with VaD. Social withdrawal was assessed with the social withdrawal of the Multidimensional Observation Scale for Elderly Subjects (MOSES). Possible explanatory variables were the MOSES items depression and self-care, Cognitive Abilities Screening Instrument (CASI), apathy evaluation scale (AES), and Behavioral Pathology in Alzheimer's Disease Frequency-Weighted Severity Scale (BEHAVE-AD-FW). Multiple regression analyses were conducted for two groups: Analysis 1 was performed in all patients (N = 36) and Analysis 2 was performed in the patients with the ability to move by themselves (i.e., independent walking or independent movement with a cane or a wheelchair; n = 28). In Analysis 1, MOSES item social withdrawal was correlated with AES and MOSES item self-care. In Analysis 2, MOSES item social withdrawal was correlated with AES and CASI domain abstraction and judgment. Decreased social activities of VaD were not related to general cognitive function or depression. Disturbed activities of daily living (ADLs) for self-care may involve decreased frontal lobe function, indicating that comprehensive rehabilitation for both ADL and dementia are needed to improve the social activities of patients with VaD.

Grandma Moses Meets Eric Carle

ERIC Educational Resources Information Center

Sutley, Jane

2012-01-01

This activity features artwork by "Grandma Moses" in which children will learn the picture plane in terms of foreground, middle ground, and background. The teacher also introduces the children to Eric Carle's colorful collaged images in his books. Using the two artists' methods, children experimented and invented new techniques and colors. As the…

Evaluation and Testing of the Suitability of a Coal-Based Jet Fuel

DTIC Science & Technology

2008-06-01

accepted that higher aromatic content increases particulate matter formation during combustion ( Naegeli and Moses, 1980; Monroig et al., 2005...Alkyl Groups. Ind. Eng. Chem. Fundam. 23, 288-294. Naegeli , D. W., Moses, C.A., 1980. Effects of Fuel Molecular Structure on Soot Formation in Gas

Altitude Ignition/Lean Decel Study.

DTIC Science & Technology

1985-11-01

Pittsburgh 1977. 26. Moses C. A. and Naegeli D. W., "Fuel Property Effects on Combustor Performance," ASME 79-GT-178, Presented at the Gas Turbine...29. Naegeli , D. W., Moses, C. A. and Mellor, A. M., "Preliminary Correlation of Fuel Effects on Ignitability for Gas Turbine Engines," ASME Paper No

Organizing the Cellular and Molecular Heterogeneity in High-Grade Serous Ovarian Cancer by Mass Cytometry

DTIC Science & Technology

2013-10-01

5b. GRANT NUMBER W81XWH-12-1-0591 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Garry P. Nolan, Ph.D. 5d. PROJECT NUMBER Wendy J . Fantl...viable HG-SOC single cells prepared from clinically anno - tated samples where the parameters measured at the single-cell level will provide critical...models by comparison of genomic profiles. Nat Commun, 2013. 4: p. 2126. 2. Coticchia, C.M., J . Yang, and M.A. Moses, Ovarian cancer biomarkers: current

Environmental Assessment, Geiger Spur Track Removal Spokane County Road Project #3091, Fairchild Air Force Base, Washington

DTIC Science & Technology

2011-03-01

breaks in glacial times and are a major part of the landscape from the Spokane area southwestward to Moses Lake and as far south as the Columbia River ...necked grebe, great blue heron, turkey vulture, Caspian tern , black tern , and osprey. The white-tailed jackrabbit, a state candidate species, is known...range activities on FAFB and along the Spokane River . Residential development is increasing in the area, mostly of rural character although several

Observation of interlayer excitons in MoSe2 single crystals

NASA Astrophysics Data System (ADS)

Horng, Jason; Stroucken, Tineke; Zhang, Long; Paik, Eunice Y.; Deng, Hui; Koch, Stephan W.

2018-06-01

Interlayer excitons with direct optical transitions are observed coexisting with intralayer excitons in the same K valleys in bilayer, few-layer, and bulk MoSe2 single crystals by confocal reflection contrast spectroscopy. Quantitative analysis using the Dirac-Bloch equations provides unambiguous state assignment of all the measured resonances. The interlayer excitons in bilayer MoSe2 have a large binding energy of 153 meV and a narrow linewidth of 20 meV. Their spectral weight is comparable to the commonly studied higher-order intralayer excitons. At the same time, the interlayer excitons are characterized by distinct transition energies and permanent dipole moments, providing a promising high temperature and optically accessible platform for dipolar exciton physics.

Moses presages Kubler-Ross: five stages in accepting death, as seen in the midrash.

PubMed

Berkowitz, M C; Knight, L

2001-11-01

This paper elucidates and explains an ancient midrash (rabbinic interpretation of a biblical text) through the lens of modern psychological theory. The midrash describes Moses' reactions to his approaching death. The paper points out that these reactions anticipate the five classic stages, described by Elizabeth Kubler-Ross, of coming to accept terminal illness: denial, anger, bargaining, depression and acceptance. The article shows the ancient rabbis' sensitivity to human feeling and the universal nature of human reaction through the dialogue and reactions they attribute to Moses. Finally, it shows how using this midrash offers a constructive model for approaching death, for Jewish and non-Jewish patients alike, as well as their caregivers.

"Between the Heavens and the Earth": Narrating the Execution of Moses Paul

ERIC Educational Resources Information Center

Salyer, Matt

2012-01-01

The 1772 execution of the Mohegan sailor Moses Paul served as the occasion for Samson Occom's popular "Sermon," reprinted in numerous editions. Recent work by Ava Chamberlain seeks to recover Paul's version of events from contemporary court records. This article argues that Paul's "firsthand" account of the case and autobiographical narrative…

An Earned Insurgency: Quality Education as a Constitutional Right

ERIC Educational Resources Information Center

Moses, Robert P.

2009-01-01

In the following pages, Robert Moses tells the history of the early civil rights movement in Mississippi, focusing on the individuals, alliances, and strategies that brought about fundamental change in the United States and ultimately made possible the election of Barack Obama to the presidency. Moses describes how the efforts of Justice…

76 FR 30908 - Foreign-Trade Zone 203-Moses Lake, Washington, Export-Only Manufacturing Authority, SGL...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-27

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [A(32b)-1-2011] Foreign-Trade Zone 203--Moses Lake, Washington, Export-Only Manufacturing Authority, SGL Automotive Carbon Fibers, LLC, (Carbon Fiber... Automotive Carbon Fibers, LLC (SGL) to manufacture carbon fiber under FTZ procedures solely for export within...

76 FR 1599 - Foreign-Trade Zone 203-Moses Lake, Washington; Application for Manufacturing Authority, SGL...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-11

... Lake, Washington; Application for Manufacturing Authority, SGL Automotive Carbon Fibers, LLC, (Carbon... manufacturing authority on behalf of SGL Automotive Carbon Fibers, LLC (SGL Automotive), located in Moses Lake... new facility will be used for the manufacture of carbon fiber, all of which will be exported for the...

Pressure-Dependent Light Emission of Charged and Neutral Excitons in Monolayer MoSe 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Xinpeng; Li, Fangfei; Lin, Jung-Fu

Tailoring the excitonic properties in two-dimensional monolayer transition metal dichalcogenides (TMDs) through strain engineering is an effective means to explore their potential applications in optoelectronics and nanoelectronics. Here we report pressure-tuned photon emission of trions and excitons in monolayer MoSe2 via a diamond anvil cell (DAC) through photoluminescence measurements and theoretical calculations. Under quasi-hydrostatic compressive strain, our results show neutral (X0) and charged (X–) exciton emission of monolayer MoSe2 can be effectively tuned by alcohol mixture vs inert argon pressure transmitting media (PTM). During this process, X– emission undergoes a continuous blue shift until reaching saturation, while X0 emission turnsmore » up splitting. The pressure-dependent charging effect observed in alcohol mixture PTM results in the increase of the X– exciton component and facilitates the pressure-tuned emission of X– excitons. This substantial tunability of X– and X0 excitons in MoSe2 can be extended to other 2D TMDs, which holds potential for developing strained and optical sensing devices.« less

Synthesis of millimeter-scale transition metal dichalcogenides single crystals

DOE PAGES

Gong, Yongji; Ye, Gonglan; Lei, Sidong; ...

2016-02-10

The emergence of semiconducting transition metal dichalcogenide (TMD) atomic layers has opened up unprecedented opportunities in atomically thin electronics. Yet the scalable growth of TMD layers with large grain sizes and uniformity has remained very challenging. Here is reported a simple, scalable chemical vapor deposition approach for the growth of MoSe2 layers is reported, in which the nucleation density can be reduced from 105 to 25 nuclei cm -2, leading to millimeter-scale MoSe 2 single crystals as well as continuous macrocrystalline films with millimeter size grains. The selective growth of monolayers and multilayered MoSe2 films with well-defined stacking orientation canmore » also be controlled via tuning the growth temperature. In addition, periodic defects, such as nanoscale triangular holes, can be engineered into these layers by controlling the growth conditions. The low density of grain boundaries in the films results in high average mobilities, around ≈42 cm 2 V -1 s -1, for back-gated MoSe 2 transistors. This generic synthesis approach is also demonstrated for other TMD layers such as millimeter-scale WSe 2 single crystals.« less

Exciton–polaritons in van der Waals heterostructures embedded in tunable microcavities

PubMed Central

Dufferwiel, S.; Schwarz, S.; Withers, F.; Trichet, A. A. P.; Li, F.; Sich, M.; Del Pozo-Zamudio, O.; Clark, C.; Nalitov, A.; Solnyshkov, D. D.; Malpuech, G.; Novoselov, K. S.; Smith, J. M.; Skolnick, M. S.; Krizhanovskii, D. N.; Tartakovskii, A. I.

2015-01-01

Layered materials can be assembled vertically to fabricate a new class of van der Waals heterostructures a few atomic layers thick, compatible with a wide range of substrates and optoelectronic device geometries, enabling new strategies for control of light–matter coupling. Here, we incorporate molybdenum diselenide/hexagonal boron nitride (MoSe2/hBN) quantum wells in a tunable optical microcavity. Part-light–part-matter polariton eigenstates are observed as a result of the strong coupling between MoSe2 excitons and cavity photons, evidenced from a clear anticrossing between the neutral exciton and the cavity modes with a splitting of 20 meV for a single MoSe2 monolayer, enhanced to 29 meV in MoSe2/hBN/MoSe2 double-quantum wells. The splitting at resonance provides an estimate of the exciton radiative lifetime of 0.4 ps. Our results pave the way for room-temperature polaritonic devices based on multiple-quantum-well van der Waals heterostructures, where polariton condensation and electrical polariton injection through the incorporation of graphene contacts may be realized. PMID:26446783

Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures.

PubMed

Zhang, Qiang; Chen, Yuxuan; Zhang, Chendong; Pan, Chi-Ruei; Chou, Mei-Yin; Zeng, Changgan; Shih, Chih-Kang

2016-12-14

The van der Waals interaction in vertical heterostructures made of two-dimensional (2D) materials relaxes the requirement of lattice matching, therefore enabling great design flexibility to tailor novel 2D electronic systems. Here we report the successful growth of MoSe 2 on single-layer hexagonal boron nitride (hBN) on the Ru(0001) substrate using molecular beam epitaxy. Using scanning tunnelling microscopy and spectroscopy, we found that the quasi-particle bandgap of MoSe 2 on hBN/Ru is about 0.25 eV smaller than those on graphene or graphite substrates. We attribute this result to the strong interaction between hBN/Ru, which causes residual metallic screening from the substrate. In addition, the electronic structure and the work function of MoSe 2 are modulated electrostatically with an amplitude of ∼0.13 eV. Most interestingly, this electrostatic modulation is spatially in phase with the Moiré pattern of hBN on Ru(0001) whose surface also exhibits a work function modulation of the same amplitude.

Multidisciplinary obstetric simulated emergency scenarios (MOSES): promoting patient safety in obstetrics with teamwork-focused interprofessional simulations.

PubMed

Freeth, Della; Ayida, Gubby; Berridge, Emma Jane; Mackintosh, Nicola; Norris, Beverley; Sadler, Chris; Strachan, Alasdair

2009-01-01

We describe an example of simulation-based interprofessional continuing education, the multidisciplinary obstetric simulated emergency scenarios (MOSES) course, which was designed to enhance nontechnical skills among obstetric teams and, hence, improve patient safety. Participants' perceptions of MOSES courses, their learning, and the transfer of learning to clinical practice were examined. Participants included senior midwives, obstetricians, and obstetric anesthetists, including course faculty from 4 purposively selected delivery suites in England. Telephone or e-mail interviews with MOSES course participants and facilitators were conducted, and video-recorded debriefings that formed integral parts of this 1-day course were analyzed. The team training was well received. Participants were able to check out assumptions and expectations of others and develop respect for different roles within the delivery suite (DS) team. Skillful facilitation of debriefing after each scenario was central to learning. Participants reported acquiring new knowledge or insights, particularly concerning the role of communication and leadership in crisis situations, and they rehearsed unfamiliar skills. Observing peers working in the simulations increased participants' learning by highlighting alternative strategies. The learning achieved by individuals and groups was noticeably dependent on their starting points. Some participants identified limited changes in their behavior in the workplace following the MOSES course. Mechanisms to manage the transfer of learning to the wider team were weakly developed, although 2 DS teams made changes to their regular update training. Interprofessional, team-based simulations promote new learning.

Little Mosie from the Margaree: A Biography of Moses Michael Coady.

ERIC Educational Resources Information Center

Welton, Michael R.

This book examines the life of the Reverend Moses Michael Coady (1890-1959), a Roman Catholic priest who led the Antigonish Movement. During the Antigonish Movement, residents of the small maritime town of Antigonish, Nova Scotia, worked to achieve a nonviolent alternative to communism and fascism and to effect the social and economic…

"A Tinge of Effeminacy": Masculinity and National Manhood in the Mosely Report, 1904

ERIC Educational Resources Information Center

Ní Bhroiméil, Úna

2015-01-01

Alfred Mosely, a wealthy South African diamond mine owner and British industrialist, financed an Educational Commission that travelled to the United States during the winter of 1903. Its purpose was to ascertain how far education in the United States was responsible for the country's industrial progress, and its report was published in England in…

Effects of Fuel Specification and Additives on Soot Formation.

DTIC Science & Technology

1983-12-01

Engine Combustor Emissions," ASME 80-GT-70, 1980. 39. Naegeli , D.W. and Moses, C.A., "Effect of Fuel Molecular Structure on Soot Formation in Gas...Symposium on Combustion, pp. 1175-1183, The Combustion Institute, 1981. 108 41. Naegeli , D.W., Dodge, L.G. and Moses, C.A., "Effect of Flame Temperature

Overview of environmental and hydrogeologic conditions at Moses Point, Alaska

USGS Publications Warehouse

Dorava, J.M.; Ayres, R.P.; Sisco, W.C.

1994-01-01

The Federal Aviation Administration facility at Moses Point is located at the mouth of the Kwiniuk River on the Seward Peninsula in northwestern Alaska. This area has long cold winters and short summers which affect the hydrology of the area. The Federal Aviation Administration owns or operates airport support facilities at the Moses Point site and wishes to consider the subsistence lifestyles of area residents and the quality of the current environment when evaluating options for remediation of environmental contamination at their facilities. Currently no operating wells are in the area, but the vulnerability of the aquifer and other alternative water supplies are being evaluated because the Federal Aviation Administration has a potential liability for the storage and use of hazardous materials in the area.

MOSE: A Demonstrator for an Automatic Operational System for the Optical Turbulence Forecast for ESO Sites

NASA Astrophysics Data System (ADS)

Masciadri, Elena; Lascaux, F.; Turchi, A.; Fini, L.

2017-09-01

"Most of the observations performed with new-generation ground-based telescopes are employing the Service Mode. To optimize the flexible-scheduling of scientific programs and instruments, the optical turbulence (OT) forecast is a must, particularly when observations are supported by adaptive optics (AO) and Interferometry. Reliable OT forecast are crucial to optimize the usage of AO and interferometric facilities which is not possible when using only optical measurements. Numerical techniques are the best placed to achieve such a goal. The MOSE project (MOdeling ESO Sites), co-funded by ESO, aimed at proving the feasibility of the forecast of (1) all the classical atmospheric parameters (such as temperature, wind speed and direction, relative humidity) and (2) the optical turbulence i.e. the CN 2 profiles and all the main integrated astro-climatic parameters derived from the CN 2 (the seeing, the isoplanatic angle, the wavefront coherence time) above the two ESO sites of Cerro Paranal and Cerro Armazones. The proposed technique is based on the use of a non-hydrostatic atmospheric meso-scale model and a dedicated code for the optical turbulence. The final goal of the project aimed at implementing an automatic system for the operational forecasts of the aforementioned parameters to support the astronomical observations above the two sites. MOSE Phase A and B have been completed and a set of dedicated papers have been published on the topic. Model performances have been extensively quantified with several dedicated figures of merit and we proved that our tool is able to provide reliable forecasts of optical turbulence and atmospheric parameters with very satisfactory score of success. This should guarantee us to make a step ahead in the framework of the Service Mode of new generation telescopes. A conceptual design as well as an operational plan of the automatic system has been submitted to ESO as integral part of the feasibility study. We completed a negotiation with ESO for the implementation of the demonstrator of system on March 2016. In this seminar I will review the principles on which the proposed technique is based on; I will briefly review the most important challenges associated to the optical turbulence forecast for ground-based observations, I will summarize the most important results we achieved at conclusion of the feasibility study, how our results open new scenarios for the operation of the most sophisticated AO systems (WFAO), the next steps for the implementation of a demonstrator and plans for the forecast of further parameters. I will conclude showing a few outputs of the operational system we implemented for the LBT in the context of a similar project (ALTA Project). "

Moringa oleifera Lam. seed extract prevents fat diet induced oxidative stress in mice and protects liver cell-nuclei from hydroxyl radical mediated damage.

PubMed

Das, Nilanjan; Ganguli, Debdutta; Dey, Sanjit

2015-12-01

High fat diet (HFD) prompts metabolic pattern inducing reactive oxygen species (ROS) production in mitochondria thereby triggering multitude of chronic disorders in human. Antioxidants from plant sources may be an imperative remedy against this disorder. However, it requires scientific validation. In this study, we explored if (i) Moringa oleifera seed extract (MoSE) can neutralize ROS generated in HFD fed mice; (ii) protect cell-nuclei damage developed by Fenton reaction in vitro. Swiss mice were fed with HFD to develop oxidative stress model (HFD group). Other groups were control, seed extract alone treated, and MoSE simultaneously (HS) treated. Treatment period was of 15 days. Antioxidant enzymes with tissue nitrite content (TNC) and lipid peroxidation (LPO) were estimated from liver homogenate. HS group showed significantly higher (P < 0.05) superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) activity, and ferric reducing antioxidant power (FRAP) compared to only HFD fed group. Further, TNC and LPO decreased significantly (P < 0.05) in HS group compared to HFD fed group. MoSE also protected hepatocytes nuclei from the hydroxyl radicals generated by Fenton reaction. MoSE was found to be polyphenol rich with potent reducing power, free radicals and hydroxyl radicals scavenging activity. Thus, MoSE exhibited robust antioxidant prospective to neutralize ROS developed in HFD fed mice and also protected the nuclei damage from hydroxyl radicals. Hence, it can be used as herbal medication against HFD induced ROS mediated disorders.

The past, present, and future of soils and human health studies

USDA-ARS?s Scientific Manuscript database

The idea that human health is tied to the soil is not a new one. As far back as approximately 1400 B.C. the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. While exploring Canaan, Moses charged the men he sent to evaluate the fertility of the soi...

Impact of Religion on Turkish Early Childhood Teachers' Factuality Judgments and Their Classroom Practice

ERIC Educational Resources Information Center

Kotaman, Hüseyin

2016-01-01

The purpose of this study is to examine the impact of religion on Turkish early childhood teachers' factuality judgments and reasoning. Participants responded following questions about the story of "Moses's stick": 1) Can Moses run water from a dry fountain just by hitting his stick to the ground? 2) Why, or why not? 3) Would you read…

A Study of Factors Affecting Soot Formation in a Swirl-Stabilized Combustor.

DTIC Science & Technology

1983-04-01

600/2-77-007a, NTIS No. PB 264068 January 1977. 8. Naegeli , D. W., and Moses, C. A., "Effect of Fuel Molecular Structure on Soot Formation in Gas...Type Turbine Combustion Systems," AFRPL-TR-79- 2072, Air Force Aero Propulsion Laboratory, April, 1980. 10. Naegeli , D. W., Dodge, L. G., and Moses, C

Fuel Microemulsions for Jet Engine Smoke Reduction

DTIC Science & Technology

1980-05-01

ESL-TR-80-25 FUEL MICROEMULSIONS FOR JET ENGINE SMOKE REDUCTION LEVEL$: 0• D.W. NAEGELI , G.E. FODOR, C.A. MOSES MOBILE ENERGY DIVISION 1N•j SOUTHWEST...Moses, C.A, and D.W. Naegeli , "Fuel Property Effects on Combustor Per- formance," AS!E Paper 79-GT-178, San Diego, CA, January 1979. 17. Naegeli , D.W

The Reverend Moses Drury Hoge and the South's Constitutional Apologia for the Civil War.

ERIC Educational Resources Information Center

Fulmer, Hal W.

The Reverend Moses Drury Hoge, one-time personal minister to Stonewall Jackson, defended secession as the South's attempt to preserve the Constitution in its original mission while eulogizing Jackson at a ceremony in 1875. Hoge drew upon the historical legacy of the American Revolution to suggest that the colonies had also formed a separate…

Vertical MoSe2-MoO x p-n heterojunction and its application in optoelectronics.

PubMed

Chen, Xiaoshuang; Liu, Guangbo; Hu, Yunxia; Cao, Wenwu; Hu, PingAn; Hu, Wenping

2018-01-26

The hybrid n-type 2D transition-metal dichalcogenide (TMD)/p-type oxide van der Waals (vdW) heterojunction nanosheets consist of 2D layered MoSe 2 (the n-type 2D material) and MoO x (the p-type oxide) which are grown on SiO 2 /Si substrates for the first time via chemical vapor deposition technique, displaying the regular hexagon structures with the average length dimension of sides of ∼8 μm. Vertical MoSe 2 -MoO x p-n heterojunctions demonstrate obviously current-rectifying characteristic, and it can be tuned via gate voltage. What is more, the photodetector based on vertical MoSe 2 -MoO x heterojunctions displays optimal photoresponse behavior, generating the responsivity, detectivity, and external quantum efficiency to 3.4 A W -1 , 0.85 × 10 8 Jones, and 1665.6%, respectively, at V ds  = 5 V with the light wavelength of 254 nm under 0.29 mW cm -2 . These results furnish a building block on investigating the flexible and transparent properties of vdW and further optimizing the structure of the devices for better optoelectronic and electronic performance.

Vertical MoSe2-MoO x p-n heterojunction and its application in optoelectronics

NASA Astrophysics Data System (ADS)

Chen, Xiaoshuang; Liu, Guangbo; Hu, Yunxia; Cao, Wenwu; Hu, PingAn; Hu, Wenping

2018-01-01

The hybrid n-type 2D transition-metal dichalcogenide (TMD)/p-type oxide van der Waals (vdW) heterojunction nanosheets consist of 2D layered MoSe2 (the n-type 2D material) and MoO x (the p-type oxide) which are grown on SiO2/Si substrates for the first time via chemical vapor deposition technique, displaying the regular hexagon structures with the average length dimension of sides of ˜8 μm. Vertical MoSe2-MoO x p-n heterojunctions demonstrate obviously current-rectifying characteristic, and it can be tuned via gate voltage. What is more, the photodetector based on vertical MoSe2-MoO x heterojunctions displays optimal photoresponse behavior, generating the responsivity, detectivity, and external quantum efficiency to 3.4 A W-1, 0.85 × 108 Jones, and 1665.6%, respectively, at V ds = 5 V with the light wavelength of 254 nm under 0.29 mW cm-2. These results furnish a building block on investigating the flexible and transparent properties of vdW and further optimizing the structure of the devices for better optoelectronic and electronic performance.

Photoluminescence nonuniformity from self-seeding nuclei in CVD-grown monolayer MoSe2.

PubMed

Tian, Xiangling; Wei, Rongfei; Liu, Shanshan; Zhang, Yeming; Qiu, Jianrong

2018-01-03

We present optical spectroscopy (photoluminescence and Raman spectrum) studies of monolayer transition metal dichalcogenide MoSe 2 , with spatial location, temperature and excitation power dependence. The investigated spectra show location-dependent behavior with an increase in photoluminescence and Raman intensity and a blue-shift in photoluminescence peak position in the inner region. The observed behaviors of a large shift in the photoluminescence peak position at the edge and biexciton emissions in the inner region confirm that the monolayer MoSe 2 crystals grow from nucleation centers during the CVD process. Temperature activated energy and dependence of the peak position are attributed to residual oxygen during the growth. Investigating this information provides a basis for precisely controlling the synthesis of TMDCs and their application in advanced optoelectronics.

Phonon-assisted oscillatory exciton dynamics in monolayer MoSe 2

DOE PAGES

Chow, Colin M.; Yu, Hongyi; Jones, Aaron M.; ...

2017-10-13

In monolayer semiconductor transition metal dichalcogenides, the exciton–phonon interaction strongly affects the photocarrier dynamics. Here, we report on an unusual oscillatory enhancement of the neutral exciton photoluminescence with the excitation laser frequency in monolayer MoSe 2. The frequency of oscillation matches that of the M-point longitudinal acoustic phonon, LA(M), suggesting the significance of zone-edge acoustic phonons and hence the deformation potential in exciton-phonon coupling in MoSe 2. Moreover, oscillatory behavior is observed in the steady-state emission linewidth and in time-resolved PLE data, which reveals variation with excitation energy in the exciton lifetime. These results clearly expose the key role playedmore » by phonons in the exciton formation and relaxation dynamics of two-dimensional van der Waals semiconductors.« less

126. Moses H. Cone Memorial Park. View of barbed wire ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

126. Moses H. Cone Memorial Park. View of barbed wire fence along carriage trail with a concrete box culvert for the carriage trail in the background. It is the only culvert on the parkway with stone veneer finished with a roman arch. It was constructed in 1960. Looking south-southeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

A Comprehensive Theory of Algorithms for Wireless Networks and Mobile Systems

DTIC Science & Technology

2016-06-08

David Peleg. Nonuniform SINR+Voronoi Diagrams are Effectively Uniform. In Yoram Moses, editor, Distributed Computing: 29th International Symposium...in Computer Science, page 559. Springer, 2014. [16] Erez Kantor, Zvi Lotker, Merav Parter, and David Peleg. Nonuniform sINR+Voronoi dia- grams are...Merav Parter, and David Peleg. Nonuniform SINR+Voronoi diagrams are effectively uniform. In Yoram Moses, editor, Distributed Computing - 29th

Fugitive from Labor Cases: Henry Garnett (1850) and Moses Honner (1860). The Constitution Community: Civil War and Reconstruction (1850-1870).

ERIC Educational Resources Information Center

Lawlor, John M., Jr.

The cases of Henry Garnett and Moses Honner bookend the 1850s, a decade of intensifying political crisis that was deeply connected to the institution of slavery. In both court actions, which were tried in the Third Circuit Court, Eastern District, Philadelphia, Pennsylvania, the defendants were charged with being "fugitives from labor."…

Spin-resolved photoemission study of epitaxially grown MoSe 2 and WSe 2 thin films

DOE PAGES

Mo, Sung-Kwan; Hwang, Choongyu; Zhang, Yi; ...

2016-09-12

Few-layer thick MoSe 2 and WSe 2 possess non-trivial spin textures with sizable spin splitting due to the inversion symmetry breaking embedded in the crystal structure and strong spin–orbit coupling. Here, we report a spin-resolved photoemission study of MoSe 2 and WSe 2 thin film samples epitaxially grown on a bilayer graphene substrate. Furthermore, we only found spin polarization in the single- and trilayer samples—not in the bilayer sample—mostly along the out-of-plane direction of the sample surface. The measured spin polarization is found to be strongly dependent on the light polarization as well as the measurement geometry, which reveals intricatemore » coupling between the spin and orbital degrees of freedom in this class of material.« less

Father and son: Freud revisits his Oedipus complex in Moses and Monotheism.

PubMed

Appelbaum, Jerome

2012-06-01

In this paper, I propose to understand Freud on his own terms and within his social, intellectual and psychological context. It is my hope that such an understanding will contribute in turn to our understanding of some of the sources of the creative process. Were it not for his fame, Freud's views on religion, history and art, would at best be but a footnote to these subjects. My contention is that Freud's writings on these subjects can contribute more to our understanding of Freud, the person, than they do to some of the subjects he is writing about. Toward this end I will focus on two of Freud's works, written more than 30 years apart, his early Moses of Michelangelo and his late-life work Moses and Monotheism, which reflect the considerable changes in Freud's thinking.

Interface exciton at lateral heterojunction of monolayer semiconductors

NASA Astrophysics Data System (ADS)

Lau, Ka Wai; Gong, Zhirui; Yu, Hongyi; Yao, Wang

Heterostructures based on 2D transition metal dichalcogenides (TMDs) have attracted extensive research interest recently due to the appealing physical properties of TMDs and new geometries for forming heterostructures. One such heterostructure is the lateral heterojunctions seamlessly formed in a monolayer crystal between two different types of TMDs, e.g. WSe2 and MoSe2. Such heterojunction exhibits a type II band alignment, with electrons (holes) having lower energy on the MoSe2 (WSe2) region. Here we present the study of an interface exciton at the 1D lateral junction of monolayer TMDs. With the distance dependent screening, we find that the interface exciton can have strong binding even though the electron-hole separation is much larger compare to the 2D excitons in TMDs. Neutral excitons are studied using two different approaches: the solution based on a real-space tight binding model, and the perturbation expansion in a hydrogen-like basis in an effective mass model. We have also used the latter method to study charged excitons at a MoSe2-WSe2-MoSe2 nanoscale junction. The work is supported by the Research Grant Council of Hong Kong (HKU705513P, HKU9/CRF/13G), the Croucher Foundation, and the HKU OYRA.

Application of Moringa Oleifera seed extract to treat coffee fermentation wastewater.

PubMed

Garde, William K; Buchberger, Steven G; Wendell, David; Kupferle, Margaret J

2017-05-05

Wastewater generated from wet processing of coffee cherries degrades stream water quality downstream of processing mills and impacts human health. The widespread popularity of coffee as an export makes this a global problem, although the immediate impact is local. Approximately 40% of all coffee around the world is wet processed, producing wastewater rich in organic nutrients that can be hazardous to aquatic systems. Moringa Oleifera Seed Extract (MOSE) offers promise as a local and affordable "appropriate" coagulation technology for aiding in the treatment of coffee wastewater. Field research was conducted at the Kauai Coffee Company to investigate the application of MOSE to treat coffee fermentation wastewater (CFW). Coagulation tests were conducted at five pH CFW levels (3-7) and MOSE doses (0-4g/L). After settling, TSS, COD, nitrate, nitrite, total nitrogen, and pH of supernatant from each test were measured. MOSE reduced TSS, COD, nitrate, and nitrite in CFW to varying degrees dependent on pH and dose applied. TSS removal ranged from 8% to 54%. Insoluble COD removal ranged from 26% to 100% and total COD removal ranged from 1% to 25%. Nitrate and nitrite reduction ranged from 20% to 100%. Copyright © 2017 Elsevier B.V. All rights reserved.

Few-Layer MoSe2 Possessing High Catalytic Activity towards Iodide/Tri-iodide Redox Shuttles

PubMed Central

Lee, Lawrence Tien Lin; He, Jian; Wang, Baohua; Ma, Yaping; Wong, King Young; Li, Quan; Xiao, Xudong; Chen, Tao

2014-01-01

Due to the two-dimensional confinement of electrons, single- and few-layer MoSe2 nanostructures exhibit unusual optical and electrical properties and have found wide applications in catalytic hydrogen evolution reaction, field effect transistor, electrochemical intercalation, and so on. Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I3− to I− at the counter electrode. The few-layer MoSe2 is fabricated by surface selenization of Mo-coated soda-lime glass. Our results show that the few-layer MoSe2 displays high catalytic efficiency for the regeneration of I− species, which in turn yields a photovoltaic energy conversion efficiency of 9.00%, while the identical photoanode coupling with “champion” electrode based on Pt nanoparticles on FTO glass generates efficiency only 8.68%. Thus, a Pt- and FTO-free counter electrode outperforming the best conventional combination is obtained. In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance. Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost. PMID:24525919

JPRS Report, Near East & South Asia

DTIC Science & Technology

1989-01-10

worshiping a cow that one of them had made. Moses rebuked his brother and fought with him because he had not prevented this regression. According to the...narrative in the chapter entitled, "Taha," verse 94, Aaron informed Moses that he did not want to prevent the regression so he would not divide...from basic problems, an opposition beset by crisis and political forces among the Egyptian men in the street who are prevented from legitimate

Screening effect of graphite and bilayer graphene on excitons in MoSe2 monolayer

NASA Astrophysics Data System (ADS)

Wang, Yuan; Zhang, Shuai; Huang, Di; Cheng, Jingxin; Li, Yingguo; Wu, Shiwei

2017-03-01

Excitons in transition metal dichalcogenide monolayer have recently attracted great interest due to their extremely large binding energy, causing giant bandgap renormalization. In this work, we examined the screening effect of graphite and bilayer graphene on the excitons in molybdenum diselenide (MoSe2) monolayer grown by molecular beam epitaxy (MBE). Through the combinational study of scanning tunneling spectroscopy (STS) and photoluminescence (PL) measurements, we determined the binding energy of ~0.58 eV for MoSe2 monolayer on both substrates at 16 K, and no obvious difference between them. Our result is consistent with a previous report [Zhang et al 2015 Nano Letters 15, 6494], but is contradictory to another one [Ugeda 2014 Nature Materials 13, 1091]. Physical picture for no noticeable difference on screening effect between bilayer graphene and graphite substrate is discussed. Possible reasons for causing the discrepancy are also mentioned.

Nonlinear dynamics of trions under strong optical excitation in monolayer MoSe2.

PubMed

Ye, Jialiang; Yan, Tengfei; Niu, Binghui; Li, Ying; Zhang, Xinhui

2018-02-05

By employing ultrafast transient reflection measurements based on two-color pump-probe spectroscopy, the population and valley polarization dynamics of trions in monolayer MoSe 2 were investigated at relatively high excitation densities under near-resonant excitation. Both the nonlinear dynamic photobleaching of the trion resonance and the redshift of the exciton resonance were found to be responsible for the excitation-energy- and density-dependent transient reflection change as a result of many-body interactions. Furthermore, from the polarization-resolved measurements, it was revealed that the initial fast population and polarization decay process upon strong photoexcitation observed for trions was determined by trion formation, transient phase-space filling and the short valley lifetime of excitons. The results provide a basic understanding of the nonlinear dynamics of population and valley depolarization of trions, as well as exciton-trion correlation in atomically thin MoSe 2 and other transition metal dichalcogenide materials.

Electrodeposition of Amorphous Molybdenum Chalcogenides from Ionic Liquids and Their Activity for the Hydrogen Evolution Reaction.

PubMed

Redman, Daniel W; Rose, Michael J; Stevenson, Keith J

2017-09-19

This work reports on the general electrodeposition mechanism of tetrachalcogenmetallates from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Both tetrathio- and tetraselenomolybdate underwent anodic electrodeposition and cathodic corrosion reactions as determined by UV-vis spectroelectrochemistry. Electrodeposition was carried out by cycling the potential between the anodic and cathodic regimes. This resulted in a film of densely packed nanoparticles of amorphous MoS x or MoSe x as determined by SEM, Raman, and XPS. The films were shown to have high activity for the hydrogen evolution reaction. The onset potential (J = 1 mA/cm 2 ) of the MoS x film was E = -0.208 V vs RHE, and that of MoSe x was E = -0.230 V vs RHE. The Tafel slope of MoS x was 42 mV/decade, and that of MoSe x was 59 mV/decade.

Electrical control of truly two-dimensional neutral and charged excitons in monolayer MoSe2

NASA Astrophysics Data System (ADS)

Ross, Jason; Wu, Sanfeng; Yu, Hongyi; Ghimire, Nirmal; Jones, Aaron; Aivazian, Grant; Yan, Jiaqiang; Mandrus, David; Xiao, Di; Xiao, Di; Xu, Xiaodong

2013-03-01

Monolayer transition metal dichalcogenides (TMDs) have emerged as ideal 2D semiconductors with valley and spin polarized excitations expected to enable true valley-tronics. Here we investigate MoSe2, a TMD which has yet to be characterized in the monolayer limit. Specifically, we examine excitons and trions (their singly charged counterparts) in the ultimate 2D limit. Utilizing high quality exfoliated MoSe2 monolayers, we report the observation and electrostatic tunability of positively charged (X +) , neutral (Xo), and negatively charged (X-) excitons via photoluminescence in FETs. The trion charging energy is large (30 meV), enhanced by strong confinement and heavy effective masses, while the linewidth is narrow (5 meV) at temperatures below 55 K. This is greater spectral contrast than in any known quasi-2D system. Further, the charging energies for X + and X- to are nearly identical implying the same effective mass for electrons and holes, which supports their recent description as massive Dirac fermions. This work demonstrates that monolayer MoSe2 is an ultimate 2D semiconductor opening the door for the investigation of truly 2D exciton physics while laying the ground work necessary to begin valley-spin polarization studies. Support: US DoE, BES, Division of MSE. HY and WY supported by Research Grant Council of Hong Kong

Narrow-band EUV Multilayer Coating for the MOSES Sounding Rocket

NASA Technical Reports Server (NTRS)

Owens, Scott M.; Gum, Jeffery S.; Tarrio, Charles; Dvorak, Joseph; Kjornrattanawanich, Benjawan; Keski-Kuha, Ritva; Thomas, Roger J.; Kankelborg, Charles C.

2005-01-01

The Multi-order Solar EUV Spectrograph (MOSES) is a slitless spectrograph designed to study solar He II emission at 303.8 Angstroms, to be launched on a sounding rocket payload. One difference between MOSES and other slitless spectrographs is that the images are recorded simultaneously at three spectral orders, m = -1,0, +l. Another is the addition of a narrow-band multilayer coating on both the grating and the fold flat, which will reject out-of-band lines that normally contaminate the image of a slitless instrument. The primary metrics f a the mating were high peak reflectivity and suppression of Fe XV and XVI emission lines at 284 Angstroms and 335 Angstroms, respectively. We chose B4C/Mg2Si for our material combination since it provides better values for all three metrics together than the other leading candidates Si/Ir, Si/B4C or Si/SiC. Measurements of witness flats at NIST indicate the peak reflectivity at 303.6 is 38.5% for a 15 bilayer stack, while the suppression at 284 Angstroms, is 4.5x and at 335 Angstroms is 18.3x for each of two reflections in the instrument. We present the results of coating the MOSES flight gratings and fold flat, including the spectral response of the fold flat and grating as measured at NIST's SURF III and Brookhaven's X24C beamline.

Effect of Al2O3 encapsulation on multilayer MoSe2 thin-film transistors

NASA Astrophysics Data System (ADS)

Lee, Hyun Ah; Yeoul Kim, Seong; Kim, Jiyoung; Choi, Woong

2017-03-01

We report the effect of Al2O3 encapsulation on the device performance of multilayer MoSe2 thin-film transistors based on statistical investigation of 29 devices with a SiO2 bottom-gate dielectric. On average, Al2O3 encapsulation by atomic layer deposition increased the field-effect mobility from 10.1 cm2 V-1 s-1 to 14.8 cm2 V-1 s-1, decreased the on/off-current ratio from 8.5  ×  105 to 2.3  ×  105 and negatively shifted the threshold voltage from  -1.1 V to  -8.1 V. Calculation based on the Y-function method indicated that the enhancement of intrinsic carrier mobility occurred independently of the reduction of contact resistance after Al2O3 encapsulation. Furthermore, contrary to previous reports in the literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method for improving the carrier mobility of multilayer MoSe2 transistors, providing important implications on the application of MoSe2 and other 2D materials into high-performance transistors.

New Lithium- and Diamine-Intercalated Superconductors Lix(CnH2n+4N2)yMoSe2 (n = 2,6)

NASA Astrophysics Data System (ADS)

Sato, Kazuki; Noji, Takashi; Hatakeda, Takehiro; Kawamata, Takayuki; Kato, Masatsune; Koike, Yoji

2018-05-01

We have succeeded in synthesizing new intercalation superconductors Lix(C2H8N2)yMoSe2 and Lix(C6H16N2)yMoSe2 with Tc = 4.2 and 3.8-6.0 K, respectively, via the co-intercalation of lithium and ethylenediamine or hexamethylenediamine into semiconducting 2H-MoSe2. It has been found that the Tc values are related not to the interlayer spacing between MoSe2 layers so much but to the electronic density of states (EDOS) at the Fermi level. Moreover, only Li-intercalated LixMoSe2 with a small interlayer spacing has been found to be non-superconducting. Accordingly, it has been concluded that not only a sufficient amount of EDOS at the Fermi level due to the charge transfer from intercalated Li to MoSe2 layers but also the enhancement of the two-dimensionality of the crystal structure and/or electronic structure due to the expansion of the interlayer spacing between MoSe2 layers is necessary for the appearance of superconductivity in MoSe2-based intercalation superconductors. The pairing mechanism and the analogy to the superconductivity in the electric double-layer transistors of 2H-MoX2 (X = S, Se, Te) are discussed.

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures.

PubMed

Chen, Ruei-San; Tang, Chih-Che; Shen, Wei-Chu; Huang, Ying-Sheng

2015-12-05

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal-semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω(-) (1) cm(-) (1), with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

PubMed Central

Chen, Ruei-San; Tang, Chih-Che; Shen, Wei-Chu; Huang, Ying-Sheng

2015-01-01

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal–semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω−1 cm−1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2. PMID:26710105

Can the date of Moses' death be determined astronomically?

NASA Astrophysics Data System (ADS)

Manetsch, T. J.; Osborn, W. H.

2011-08-01

There is an early Jewish tradition that the sun darkened on the day of Moses' death. The possibility of this being a reference to a solar eclipse has been investigated. If such were to be the case, identification of the eclipse could be used to derive dates for events recorded in the Bible. A likely candidate eclipse has been found that fits well with Hebrew calendar dates and timelines that are recorded in the biblical books of Deuteronomy and Joshua.

Charge density wave order in 1D mirror twin boundaries of single-layer MoSe 2

DOE PAGES

Barja, Sara; Wickenburg, Sebastian; Liu, Zhen-Fei; ...

2016-04-18

Here, We provide direct evidence for the existence of isolated, one-dimensional charge density waves at mirror twin boundaries (MTBs) of single-layer semiconducting MoSe 2. Such MTBs have been previously observed by transmission electron microscopy and have been predicted to be metallic in MoSe 2 and MoS 2. Our low-temperature scanning tunnelling microscopy/spectroscopy measurements revealed a substantial bandgap of 100 meV opening at the Fermi energy in the otherwise metallic one-dimensional structures. We found a periodic modulation in the density of states along the MTB, with a wavelength of approximately three lattice constants. In addition to mapping the energy-dependent densitymore » of states, we determined the atomic structure and bonding of the MTB through simultaneous high-resolution non-contact atomic force microscopy. Density functional theory calculations based on the observed structure reproduced both the gap opening and the spatially resolved density of states.« less

[Freud's identification with men who had 2 mothers: Oedipus, Leonardo da Vinci, Michealangelo and Moses].

PubMed

Harsch, H E

1994-02-01

In view of the fact that as a child Sigmund Freud was looked after by two mothers--his actual mother and a nursemaid--it is hardly surprising that traces of this pre-oedipal situation, fraught as it was with traumatisation and loss, should be discernible in the works of the creator of psychoanalysis. Freud's continued preoccupation with the Oedipus myth, his interest in "great men" like da Vinci and Michelangelo, and finally his identification with the figure of Moses are pointers not only to the paternal dimension (as long suggested by Freud's biographers) but also to the maternal dimension and its significance for Freud's life and work. The author demonstrates that those mythical and historical figures which Freud identified with--Oedipus, da Vinci, Michelangelo, Moses--themselves all had two mothers and sublimated this traumatic experience into outstanding achievements, the same being true of Freud himself "who solved the famous riddle and was a most powerful man".

Pressure induced metallization with absence of structural transition in layered molybdenum diselenide

PubMed Central

Zhao, Zhao; Zhang, Haijun; Yuan, Hongtao; Wang, Shibing; Lin, Yu; Zeng, Qiaoshi; Xu, Gang; Liu, Zhenxian; Solanki, G. K.; Patel, K. D.; Cui, Yi; Hwang, Harold Y.; Mao, Wendy L.

2015-01-01

Layered transition-metal dichalcogenides have emerged as exciting material systems with atomically thin geometries and unique electronic properties. Pressure is a powerful tool for continuously tuning their crystal and electronic structures away from the pristine states. Here, we systematically investigated the pressurized behavior of MoSe2 up to ∼60 GPa using multiple experimental techniques and ab-initio calculations. MoSe2 evolves from an anisotropic two-dimensional layered network to a three-dimensional structure without a structural transition, which is a complete contrast to MoS2. The role of the chalcogenide anions in stabilizing different layered patterns is underscored by our layer sliding calculations. MoSe2 possesses highly tunable transport properties under pressure, determined by the gradual narrowing of its band-gap followed by metallization. The continuous tuning of its electronic structure and band-gap in the range of visible light to infrared suggest possible energy-variable optoelectronics applications in pressurized transition-metal dichalcogenides. PMID:26088416

Venice: Fifty years after the great flood of November 4, 1966

NASA Astrophysics Data System (ADS)

Rizzoli, P. M.

2017-12-01

Fifty years ago Venice and its lagoon suffered the most devastating flood in their millennial history. The causes of the increasingly recurring floods will be examined, namely the man-induced subsidence in the period 1925-1970 and the storm surges of the Adriatic sea. The engineering solution designed for their protection , named the MOSE system, will be discussed in detail. The MOSE was started in 2003 and is near completion. It consists of four barriers , invisible in normal conditions, which will close the inlets to the lagoon under the prediction of a forthcoming flood. Finally, the perspective of the MOSE capability of protecting the city under scenarios of future global sea level rise will be assessed. This assessment must critically take into account that Venice and its lagoon are confined in the northernmost corner of the semi-enclosed, marginal Mediterranean sea for which the uncertainties of future sea level rise greatly exceed the uncertainties of the global averages.

Carbon Dioxide Electroreduction into Syngas Boosted by a Partially Delocalized Charge in Molybdenum Sulfide Selenide Alloy Monolayers.

PubMed

Xu, Jiaqi; Li, Xiaodong; Liu, Wei; Sun, Yongfu; Ju, Zhengyu; Yao, Tao; Wang, Chengming; Ju, Huanxin; Zhu, Junfa; Wei, Shiqiang; Xie, Yi

2017-07-24

Structural parameters of ternary transition-metal dichalcogenide (TMD) alloy usually obey Vegard law well, while interestingly it often exhibits boosted electrocatalytic performances relative to its two pristine binary TMDs. To unveil the underlying reasons, we propose an ideal model of ternary TMDs alloy monolayer. As a prototype, MoSeS alloy monolayers are successfully synthesized, in which X-ray absorption fine structure spectroscopy manifests their shortened Mo-S and lengthened Mo-Se bonds, helping to tailor the d-band electronic structure of Mo atoms. Density functional theory calculations illustrate an increased density of states near their conduction band edge, which ensures faster electron transfer confirmed by their lower work function and smaller charge-transfer resistance. Energy calculations show the off-center charge around Mo atoms not only benefits for stabilizing COOH* intermediate confirmed by its most negative formation energy, but also facilitates the rate-limiting CO desorption step verified by CO temperature programmed desorption and electro-stripping tests. As a result, MoSeS alloy monolayers attain the highest 45.2 % Faradaic efficiency for CO production, much larger than that of MoS 2 monolayers (16.6 %) and MoSe 2 monolayers (30.5 %) at -1.15 V vs. RHE. This work discloses how the partially delocalized charge in ternary TMDs alloys accelerates electrocatalytic performances at atomic level, opening new horizons for manipulating CO 2 electroreduction properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuning contact transport mechanisms in bilayer MoSe2 transistors up to Fowler-Nordheim regime

NASA Astrophysics Data System (ADS)

Mouafo, L. D. N.; Godel, F.; Froehlicher, G.; Berciaud, S.; Doudin, B.; Venkata Kamalakar, M.; Dayen, J.-F.

2017-03-01

Atomically thin molybdenum diselenide (MoSe2) is an emerging two-dimensional (2D) semiconductor with significant potential for electronic, optoelectronic, spintronic applications and a common platform for their possible integration. Tuning interface charge transport between such new 2D materials and metallic electrodes is a key issue in 2D device physics and engineering. Here, we report tunable interface charge transport in bilayer MoSe2 field effect transistors with Ti/Au contacts showing high on/off ratio up to 107 at room temperature. Our experiments reveal a detailed map of transport mechanisms obtained by controlling the interface band bending profile via temperature, gate and source-drain bias voltages. This comprehensive investigation leads to demarcating regimes and tuning in transport mechanisms while controlling the interface barrier profile. The careful analysis allows us to identify thermally activated regime at low carrier density, and Schottky barrier driven mechanisms at higher carrier density demonstrating the transition from low-field direct tunneling/ thermionic emission to high-field Fowler-Nordheim tunneling. Furthermore, we show that the transition voltage Vtrans to Fowler-Nordheim correlates directly to the difference between the chemical potential of the metal electrode and the conduction band minimum in the 2D semiconductor, which opens up opportunities for new theoretical and experimental investigations. Our approach being generic can be extended to other 2D materials, and the possibility of tuning contact transport regimes is promising for designing MoSe2 device applications.

Relativistic extension of the Kay-Moses method for constructing transparent potentials in quantum mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toyama, F.M.; Nogami, Y.; Zhao, Z.

1993-02-01

For the Dirac equation in one space dimension with a potential of the Lorentz scalar type, we present a complete solution for the problem of constructing a transparent potential. This is a relativistic extension of the Kay-Moses method which was developed for the nonrelativistic Schroedinger equation. There is an infinite family of transparent potentials. The potentials are all related to solutions of a class of coupled, nonlinear Dirac equations. In addition, it is argued that an admixture of a Lorentz vector component in the potential impairs perfect transparency.

Water balance analysis for efficient water allocation in agriculture. A case study: Balta Brailei, Romania

NASA Astrophysics Data System (ADS)

Chitu, Zenaida; Villani, Giulia; Tomei, Fausto; Minciuna, Marian; Aldea, Adrian; Dumitrescu, Alexandru; Trifu, Cristina; Neagu, Dumitru

2017-04-01

Balta Brailei is one of the largest agriculture area in the Danube floodplain, located in SE of Romania. An impressive irrigation system, that covered about 53.500 ha and transferred water from the Danube River, was carried out in the period 1960-1980. Even if the water resources for agriculture in this area cover in most of the cases the volumes required by irrigation water users, the irrigation infrastructure issues as the position of the pumping stations against the river levels hinder the use of the water during low flows periods. An efficient optimization of water allocation in agriculture could avoid periods with water deficit in the irrigation systems. Hydrological processes are essentials in describing the mass and energy exchanges in the atmosphere-plant-soil system. Furthermore, the hydrological regime in this area is very dynamic with many feedback mechanisms between the various parts of the surface and subsurface water regimes. Agricultural crops depend on capillary rise from the shallow groundwater table and irrigation. For an effective optimization of irrigation water in Balta Brailei, we propose to analyse the water balance taking into consideration the water movement into the root zone and the influence of the Danube river, irrigation channel system and the shallow aquifer by combining the soil water balance model CRITERIA and GMS hydrogeological model. CRITERIA model is used for simulating water movement into the soil, while GMS model is used for simulating the shallow groundwater level variation. The understanding of the complex feedbacks between atmosphere, crops and the various parts of the surface and subsurface water regimes in the Balta Brailei will bring more insights for predicting crop water need and water resources for irrigation and it will represent the basis for implementing Moses Platform in this specific area. Moses Platform is a GIS based system devoted to water procurement and management agencies to facilitate planning of irrigation water resources. This work is financed by the European Union's H2020 research and innovation programme under grant agreement No 642258 (Moses Project).

Explosive Events in the Quiet Sun: Extreme Ultraviolet Imaging Spectroscopy Instrumentation and Observations

NASA Astrophysics Data System (ADS)

Rust, Thomas Ludwell

Explosive event is the name given to slit spectrograph observations of high spectroscopic velocities in solar transition region spectral lines. Explosive events show much variety that cannot yet be explained by a single theory. It is commonly believed that explosive events are powered by magnetic reconnection. The evolution of the line core appears to be an important indicator of which particular reconnection process is at work. The Multi-Order Solar Extreme Ultraviolet Spectrograph (MOSES) is a novel slitless spectrograph designed for imaging spectroscopy of solar extreme ultraviolet (EUV) spectral lines. The spectrograph design forgoes a slit and images instead at three spectral orders of a concave grating. The images are formed simultaneously so the resulting spatial and spectral information is co-temporal over the 20' x 10' instrument field of view. This is an advantage over slit spectrographs which build a field of view one narrow slit at a time. The cost of co-temporal imaging spectroscopy with the MOSES is increased data complexity relative to slit spectrograph data. The MOSES data must undergo tomographic inversion for recovery of line profiles. I use the unique data from the MOSES to study transition region explosive events in the He ii 304 A spectral line. I identify 41 examples of explosive events which include 5 blue shifted jets, 2 red shifted jets, and 10 bi-directional jets. Typical doppler speeds are approximately 100kms-1. I show the early development of one blue jet and one bi-directional jet and find no acceleration phase at the onset of the event. The bi-directional jets are interesting because they are predicted in models of Petschek reconnection in the transition region. I develop an inversion algorithm for the MOSES data and test it on synthetic observations of a bi-directional jet. The inversion is based on a multiplicative algebraic reconstruction technique (MART). The inversion successfully reproduces synthetic line profiles. I then use the inversion to study the time evolution of a bi-directional jet. The inverted line profiles show fast doppler shifted components and no measurable line core emission. The blue and red wings of the jet show increasing spatial separation with time.

Etching-free patterning method for electrical characterization of atomically thin MoSe2 films grown by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Utama, M. Iqbal Bakti; Lu, Xin; Zhan, Da; Ha, Son Tung; Yuan, Yanwen; Shen, Zexiang; Xiong, Qihua

2014-10-01

Patterning two-dimensional materials into specific spatial arrangements and geometries is essential for both fundamental studies of materials and practical applications in electronics. However, the currently available patterning methods generally require etching steps that rely on complicated and expensive procedures. We report here a facile patterning method for atomically thin MoSe2 films using stripping with an SU-8 negative resist layer exposed to electron beam lithography. Additional steps of chemical and physical etching were not necessary in this SU-8 patterning method. The SU-8 patterning was used to define a ribbon channel from a field effect transistor of MoSe2 film, which was grown by chemical vapor deposition. The narrowing of the conduction channel area with SU-8 patterning was crucial in suppressing the leakage current within the device, thereby allowing a more accurate interpretation of the electrical characterization results from the sample. An electrical transport study, enabled by the SU-8 patterning, showed a variable range hopping behavior at high temperatures.Patterning two-dimensional materials into specific spatial arrangements and geometries is essential for both fundamental studies of materials and practical applications in electronics. However, the currently available patterning methods generally require etching steps that rely on complicated and expensive procedures. We report here a facile patterning method for atomically thin MoSe2 films using stripping with an SU-8 negative resist layer exposed to electron beam lithography. Additional steps of chemical and physical etching were not necessary in this SU-8 patterning method. The SU-8 patterning was used to define a ribbon channel from a field effect transistor of MoSe2 film, which was grown by chemical vapor deposition. The narrowing of the conduction channel area with SU-8 patterning was crucial in suppressing the leakage current within the device, thereby allowing a more accurate interpretation of the electrical characterization results from the sample. An electrical transport study, enabled by the SU-8 patterning, showed a variable range hopping behavior at high temperatures. Electronic supplementary information (ESI) available: Further experiments on patterning and additional electrical characterizations data. See DOI: 10.1039/c4nr03817g

Suppression of Defects and Deep Levels Using Isoelectronic Tungsten Substitution in Monolayer MoSe 2

DOE PAGES

Li, Xufan; Puretzky, Alexander A.; Sang, Xiahan; ...

2017-05-18

Chemical vapor deposition (CVD) is one of the most promising, scalable synthetic techniques to enable large-area synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) for the realization of next generation optoelectronic devices. However, defects formed during the CVD growth process currently limit the quality and electronic properties of 2D TMDs. Effective synthesis and processing strategies to suppress defects and enhance the quality of 2D TMDs are urgently needed. In this work, isoelectrnic doping to produce stable alloy is presented as a new strategy to suppress defects and enhance photoluminescence (PL) in CVD-grown TMD monolayers. The random, isoelectronic substitution of Wmore » atoms for Mo atoms in CVD-grown monolayers of Mo 1-xW xSe 2 (02 monolayers. The resultant decrease in defect-medicated non-radiative recombination in the Mo 0.82W 0.18Se 2 monolayers yielded ~10 times more intense PL and extended the carrier lifetime by a factor of 3 compared to pristine CVD-grown MoSe 2 monolayers grown under similar conditions. Low temperatures (4 125 K) PL from defect-related localized states confirms theoretical predictions that isoelectronic W alloying should suppress deep levels in MoSe 2, showing that the defect levels in Mo 1-xW xSe 2 monolayers are higher in energy and quenched more quickly than in MoSe 2. Isoelectronic substitution therefore appears to be a promising synthetic method to control the heterogeneity of 2D TMDs to realize the scalable production of high performance optoelectronic and electronic devices.« less

Suppression of Defects and Deep Levels Using Isoelectronic Tungsten Substitution in Monolayer MoSe 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xufan; Puretzky, Alexander A.; Sang, Xiahan

Chemical vapor deposition (CVD) is one of the most promising, scalable synthetic techniques to enable large-area synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) for the realization of next generation optoelectronic devices. However, defects formed during the CVD growth process currently limit the quality and electronic properties of 2D TMDs. Effective synthesis and processing strategies to suppress defects and enhance the quality of 2D TMDs are urgently needed. In this work, isoelectrnic doping to produce stable alloy is presented as a new strategy to suppress defects and enhance photoluminescence (PL) in CVD-grown TMD monolayers. The random, isoelectronic substitution of Wmore » atoms for Mo atoms in CVD-grown monolayers of Mo 1-xW xSe 2 (02 monolayers. The resultant decrease in defect-medicated non-radiative recombination in the Mo 0.82W 0.18Se 2 monolayers yielded ~10 times more intense PL and extended the carrier lifetime by a factor of 3 compared to pristine CVD-grown MoSe 2 monolayers grown under similar conditions. Low temperatures (4 125 K) PL from defect-related localized states confirms theoretical predictions that isoelectronic W alloying should suppress deep levels in MoSe 2, showing that the defect levels in Mo 1-xW xSe 2 monolayers are higher in energy and quenched more quickly than in MoSe 2. Isoelectronic substitution therefore appears to be a promising synthetic method to control the heterogeneity of 2D TMDs to realize the scalable production of high performance optoelectronic and electronic devices.« less

Large-area synthesis and photoelectric properties of few-layer MoSe2 on molybdenum foils

NASA Astrophysics Data System (ADS)

Wu, Zenghui; Tai, Guoan; Wang, Xufeng; Hu, Tingsong; Wang, Rui; Guo, Wanlin

2018-03-01

Compared with MoS2 and WS2, selenide analogs have narrower band gaps and higher electron mobilities, which make them more applicable to real electrical devices. In addition, few-layer metal selenides have higher electrical conductivity, carrier mobility and light absorption than the corresponding monolayers. However, the large-scale and high-quality growth of few-layer metal selenides remains a significant challenge. Here, we develop a facile method to grow large-area and highly crystalline few-layer MoSe2 by directly selenizing the Mo foil surface at 550 °C within 60 min under ambient pressure. The atomic layers were controllably grown with thicknesses between 3.4 and 6 nm, which just met the thickness range required for high-performance electrical devices. Furthermore, we fabricated a vertical p-n junction photodetector composed of few-layer MoSe2 and p-type silicon, achieving photoresponsivity higher by two orders of magnitude than that of the reported monolayer counterpart. This technique provides a feasible approach towards preparing other 2D transition metal dichalcogendes for device applications.

Photoinduced charge transfer from vacuum-deposited molecules to single-layer transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Osada, Kazuki; Tanaka, Masatoshi; Ohno, Shinya; Suzuki, Takanori

2016-06-01

Variations of photoluminescence (PL) and Raman spectra of single-layer MoS2, MoSe2, WS2, and WSe2 due to the vacuum deposition of C60 or copper phthalocyanine (CuPc) molecules have been investigated. PL spectra are decomposed into two competitive components, an exciton and a charged exciton (trion), depending on carrier density. The variation of PL spectra is interpreted in terms of charge transfer across the interfaces between transition metal dichalcogenides (TMDs) and dopant molecules. We find that deposited C60 molecules inject photoexcited electrons into MoS2, MoSe2, and WS2 or holes into WSe2. CuPc molecules also inject electrons into MoS2, MoSe2, and WS2, while holes are depleted from WSe2 to CuPc. We then propose a band alignment between TMDs and dopant molecules. Peak shifts of Raman spectra and doped carrier density estimated using a three-level model also support the band alignment. We thus demonstrate photoinduced charge transfer from dopant molecules to single-layer TMDs.

An evaluation of various methods of treatment for Legg-Calvé-Perthes disease.

PubMed

Wang, L; Bowen, J R; Puniak, M A; Guille, J T; Glutting, J

1995-05-01

An analysis of 5 methods of treatment for Legg-Calvé-Perthes disease was done on 124 patients with 141 affected hips. Before treatment, all groups were statistically similar concerning initial Mose measurement, age at onset of the disease, gender, and Catterall class. Treatments included the Scottish Rite orthosis (41 hips), nonweight bearing and exercises (41 hips), Petrie cast (29 hips), femoral varus osteotomy (15 hips), or Salter osteotomy (15 hips). Hips treated by the Scottish Rite orthosis had a significantly worse Mose measurement across time interaction (repeated measures analysis of variance, post hoc analyses, p < 0.05). For the other 4 treatment methods, there was no statistically different change. At followup, the Mose measurements for hips treated with the Scottish Rite orthosis were significantly worse than those for hips treated by nonweight bearing and exercises, Petrie cast, varus osteotomy, or Salter osteotomy (repeated measures analysis of variance, post hoc analyses, p < 0.05). There was, however, no significant difference in the distribution of hips according to the Stulberg et al classification at the last followup.

Etching-free patterning method for electrical characterization of atomically thin MoSe2 films grown by chemical vapor deposition.

PubMed

Utama, M Iqbal Bakti; Lu, Xin; Zhan, Da; Ha, Son Tung; Yuan, Yanwen; Shen, Zexiang; Xiong, Qihua

2014-11-07

Patterning two-dimensional materials into specific spatial arrangements and geometries is essential for both fundamental studies of materials and practical applications in electronics. However, the currently available patterning methods generally require etching steps that rely on complicated and expensive procedures. We report here a facile patterning method for atomically thin MoSe2 films using stripping with an SU-8 negative resist layer exposed to electron beam lithography. Additional steps of chemical and physical etching were not necessary in this SU-8 patterning method. The SU-8 patterning was used to define a ribbon channel from a field effect transistor of MoSe2 film, which was grown by chemical vapor deposition. The narrowing of the conduction channel area with SU-8 patterning was crucial in suppressing the leakage current within the device, thereby allowing a more accurate interpretation of the electrical characterization results from the sample. An electrical transport study, enabled by the SU-8 patterning, showed a variable range hopping behavior at high temperatures.

Experimental Determination of the Ionization Energies of MoSe 2, WS 2, and MoS 2 on SiO 2 Using Photoemission Electron Microscopy

DOE PAGES

Keyshar, Kunttal; Berg, Morgann; Zhang, Xiang; ...

2017-07-19

Here, the values of the ionization energies of transition metal dichalcogenides (TMDs) are needed to assess their potential usefulness in semiconductor heterojunctions for high-performance optoelectronics. Here, we report on the systematic determination of ionization energies for three prototypical TMD monolayers (MoSe 2, WS 2, and MoS 2) on SiO 2 using photoemission electron microscopy with deep ultraviolet illumination. The ionization energy displays a progressive decrease from MoS 2, to WS 2, to MoSe 2, in agreement with predictions of density functional theory calculations. Combined with the measured energy positions of the valence band edge at the Brillouin zone center, wemore » deduce that, in the absence of interlayer coupling, a vertical heterojunction comprising any of the three TMD monolayers would form a staggered (type-II) band alignment. This band alignment could give rise to long-lived interlayer excitons that are potentially useful for valleytronics or efficient electron–hole separation in photovoltaics.« less

Highly Oriented Atomically Thin Ambipolar MoSe2 Grown by Molecular Beam Epitaxy

PubMed Central

2017-01-01

Transition metal dichalcogenides (TMDCs), together with other two-dimensional (2D) materials, have attracted great interest due to the unique optical and electrical properties of atomically thin layers. In order to fulfill their potential, developing large-area growth and understanding the properties of TMDCs have become crucial. Here, we have used molecular beam epitaxy (MBE) to grow atomically thin MoSe2 on GaAs(111)B. No intermediate compounds were detected at the interface of as-grown films. Careful optimization of the growth temperature can result in the growth of highly aligned films with only two possible crystalline orientations due to broken inversion symmetry. As-grown films can be transferred onto insulating substrates, allowing their optical and electrical properties to be probed. By using polymer electrolyte gating, we have achieved ambipolar transport in MBE-grown MoSe2. The temperature-dependent transport characteristics can be explained by the 2D variable-range hopping (2D-VRH) model, indicating that the transport is strongly limited by the disorder in the film. PMID:28530829

Spectroscopy of Moses Rock Kimberlite Diatreme

NASA Technical Reports Server (NTRS)

Pieters, C. M.; Mustard, J. F.

1985-01-01

Three types of remote sensing data (Airborne Imaging Spectroscopy (AIS), NS001, Zeiss IR-photographs) were obtained for the Moses Rock kimberlite dike in southern Utah. The goal is to identify and characterize the mantle derived mafic component in such volcanic features. The Zeiss and NS001 images provide information on the regional setting and allow units of the dike to be distinguished from surrounding material. A potential unmapped satellite dike was identified. The AIS data provide characterizing information of the surface composition of the dike. Serpentized olivine-bearing soils are (tentatively) identified from the AIS spectra for a few areas within the dike.

FootFall: A Ground Based Operations Toolset Enabling Walking for the ATHLETE Rover

NASA Technical Reports Server (NTRS)

SunSpiral, Vytas; Chavez-Clemente, Daniel; Broxton, Michael; Keely, Leslie; Mihelich, Patrick; Mittman, David; Collins, Curtis

2008-01-01

The ATHLETE (All-Terrain Hex-Limbed Extra-Terrestrial Explorer) vehicle consists of six identical, six degree of freedom limbs. FootFall is a ground tool for ATHLETE intended to provide an operator with integrated situational awareness, terrain reconstruction, stability and safety analysis, motion planning, and decision support capabilities to enable the efficient generation of flight software command sequences for walking. FootFall has been under development at NASA Ames for the last year, and having accomplished the initial integration, it is being used to generate command sequences for single footfalls. In this paper, the architecture of FootFall in its current state will be presented, results from the recent Human Robotic Systems Project?s Integrated Field Test (Moses Lake, Washington, June, 2008) will be discussed, and future plans for extending the capabilities of FootFall to enable ATHLETE to walk across a boulder field in real time will be described.

Optical Design of the MOSES Sounding Rocket Experiment

NASA Technical Reports Server (NTRS)

Thomas, Roger J.; Kankelborg, Charles C.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The Multi-Order Solar EUV Spectrograph (MOSES) is a sounding rocket payload now being developed by Montana State University in collaboration with the Goddard Space Flight Center, Lockheed Martin Advanced Technology Center, and Mullard Space Science Laboratory. The instrument utilizes a unique optical design to provide solar EUV measurements with true 2-pixel resolutions of 1.0 arcsec and 60 mA over a full two-dimensional field of view of 1056 x 528 arcsec, all at a time cadence of 10 s. This unprecedented capability is achieved by means of an objective spherical grating 100 mm in diameter, ruled at 833 gr/mm. The concave grating focuses spectrally dispersed solar radiation onto three separate detectors, simultaneously recording the zero-order as well as the plus and minus first-spectral-order images. Data analysis procedures, similar to those used in X-ray tomography reconstructions, can then disentangle the mixed spatial and spectral information recorded by the multiple detectors. A flat folding mirror permits an imaging focal length of 4.74 m to be packaged within the payload's physical length of 2.82 m. Both the objective grating and folding flat have specialized, closely matched, multilayer coatings that strongly enhance their EUV reflectance while also suppressing off-band radiation that would otherwise complicate data inversion. Although the spectral bandpass is rather narrow, several candidate wavelength intervals are available to carry out truly unique scientific studies of the outer solar atmosphere. Initial flights of MOSES, scheduled to begin in 2004, will observe a 10 Angstrom band that covers very strong emission lines characteristic of both the sun's corona (Si XI 303 Angstroms) and transition-region (He II 304 Angstroms). The MOSES program is supported by a grant from NASA's Office of Space Science.

3D-hierarchical MoSe2 nanoarchitecture as a highly efficient electrocatalyst for hydrogen evolution

NASA Astrophysics Data System (ADS)

Zheng, Binjie; Chen, Yuanfu; Qi, Fei; Wang, Xinqiang; Zhang, Wanli; Li, Yanrong; Li, Xuesong

2017-06-01

Clean hydrogen split from water by hydrogen evolution reaction (HER) is significant for sustainability, environmental emissions, and energy security. So far, it is still a big challenge to develop highly efficient noble metal-free electrocatalysts with comparable HER efficiency to platinum-based catalysts, which are mainly hindered by the intrinsic electrocatalytic property and particularly the reasonable nanostructure design of the electrocatalyst. Here we report a newly-designed three-dimensional hierarchical MoSe2 nanoarchitecture (3D-MoSe2) with outstanding HER performance. The 3D-MoSe2 is grown by chemical vapor deposition method with using perylene-3, 4, 9, 10-tetracarboxylic acid tetrapotassium salt as a seeding promoter. The as-grown 3D-MoSe2 nanoarchitecture is highly crystalline and constructed with curly few-layered vertical nanosheets onto the horizontal layer, which has much larger (~12 times) electrochemically active area and much smaller (only 2%) charge transfer resistance compared to conventional horizontal MoSe2 layer. With these advantages, the Tafel slope of 3D-MoSe2 can be as small as 47.3 mV/dev, which is the smallest record ever reported for pure MoSe2, even for pure two-dimensional transition metal dichalcogenides (2D-TMDs) catalysts. Furthermore, when 3D-MoSe2 is grown on the multiwall carbon nanotube film, its Tafel slope can be further reduced down to 32.5 mV/dec, which is close to the theoretical limit (29 mV/dec) of HER, and comparable to platinum-based electrocatalysts, making it promising as a highly efficient electrocatalyst for hydrogen evolution.

Ab-initio study of superconducting state in intercalated MoSe2 and WSe2 bilayers

NASA Astrophysics Data System (ADS)

Szcześniak, R.; Durajski, A. P.; Jarosik, M. W.

2018-05-01

A two-dimensional systems have attracted significant interest due to their outstanding physical, chemical and optoelectronic properties. This paper focuses on the detailed investigations of the electronic, phononic and superconducting properties of transition-metal dichalcogenide bilayers MSe 2 (M = Mo, W) intercalated by calcium atoms. The first-principles calculations show that (MoSe2)2Ca and (WSe2)2Ca systems exhibit metallic behavior and weak phonon-mediated superconductivity with low critical temperature of 0.51 and 0.30 K, respectively. These results confirm other theoretical predictions and suggest that the investigated materials cannot be a good candidates for a nanoscale superconductors.

Hydrophilic MoSe2 Nanosheets as Effective Photothermal Therapy Agents and Their Application in Smart Devices.

PubMed

Lei, Zhouyue; Zhu, Wencheng; Xu, Shengjie; Ding, Jian; Wan, Jiaxun; Wu, Peiyi

2016-08-17

A facile poly(vinylpyrrolidone) (PVP)-assisted exfoliation method is utilized to simultaneously exfoliate and noncovalently modify MoSe2 nanosheets. The resultant hydrophilic nanosheets are shown to be promising candidates for biocompatible photothermal therapy (PTT) agents, and they could also be encapsulated into a hydrogel matrix for some intelligent devices. This work not only provides novel insights into exfoliation and modification of transition metal dichalcogenide (TMD) nanosheets but also might spark more research into engineering multifunctional TMD-related nanocomposites, which is in favor of further exploiting the attractive properties of these emerging layered two-dimensional (2D) nanomaterials.

Moses meets Kübler-Ross: the five stages toward accepting death as seen in the Midrash.

PubMed

Berkowitz, M C

2001-01-01

Elucidates and explains an ancient Midrash (rabbinic interpretation of biblical text, @ 400-600 CE) through the lens of modern psychological theory. Describes Moses's reactions to his approaching death and points out that his reactions follow closely the five classic stages of coming to terms with terminal illness. Brings to light and analyzes a text previously inaccessible to the non-specialist and notes practical applications for pastoral caregivers in dealing with the terminally ill in general. Suggests reasons why Jewish patients may be particularly resistant to accepting death and how using this Midrash could offer a constructive model to approaching death.

Erbium-doped fiber laser passively mode locked with few-layer WSe2/MoSe2 nanosheets

NASA Astrophysics Data System (ADS)

Mao, Dong; She, Xiaoyang; Du, Bobo; Yang, Dexing; Zhang, Wending; Song, Kun; Cui, Xiaoqi; Jiang, Biqiang; Peng, Tao; Zhao, Jianlin

2016-03-01

Few-layer transition-metal dichalcogenide WSe2/MoSe2 nanosheets are fabricated by a liquid exfoliation technique using sodium deoxycholate bile salt as surfactant, and their nonlinear optical properties are investigated based on a balanced twin-detector measurement scheme. It is demonstrated that both types of nanosheets exhibit nonlinear saturable absorption properties at the wavelength of 1.55 μm. By depositing the nanosheets on side polished fiber (SPF) or mixing the nanosheets with polyvinyl alcohol (PVA) solution, SPF-WSe2 saturable absorber (SA), SPF-MoSe2 SA, PVA-WSe2 SA, and PVA-MoSe2 SA are successfully fabricated and further tested in erbium-doped fiber lasers. The SPF-based SA is capable of operating at the high pump regime without damage, and a train of 3252.65 MHz harmonically mode-locked pulses are obtained based on the SPF-WSe2 SA. Soliton mode locking operations are also achieved in the fiber laser separately with other three types of SAs, confirming that the WSe2 and MoSe2 nanosheets could act as cost-effective high-power SAs for ultrafast optics.

Using local correlation tracking to recover solar spectral information from a slitless spectrograph

NASA Astrophysics Data System (ADS)

Courrier, Hans T.; Kankelborg, Charles C.

2018-01-01

The Multi-Order Solar EUV Spectrograph (MOSES) is a sounding rocket instrument that utilizes a concave spherical diffraction grating to form simultaneous images in the diffraction orders m=0, +1, and -1. MOSES is designed to capture high-resolution cotemporal spectral and spatial information of solar features over a large two-dimensional field of view. Our goal is to estimate the Doppler shift as a function of position for every MOSES exposure. Since the instrument is designed to operate without an entrance slit, this requires disentangling overlapping spectral and spatial information in the m=±1 images. Dispersion in these images leads to a field-dependent displacement that is proportional to Doppler shift. We identify these Doppler shift-induced displacements for the single bright emission line in the instrument passband by comparing images from each spectral order. We demonstrate the use of local correlation tracking as a means to quantify these differences between a pair of cotemporal image orders. The resulting vector displacement field is interpreted as a measurement of the Doppler shift. Since three image orders are available, we generate three Doppler maps from each exposure. These may be compared to produce an error estimate.

Abundance and distribution of ultramafic microbreccia in Moses Rock Dike: Quantitative application of AIS data

NASA Technical Reports Server (NTRS)

Mustard, John F.; Pieters, Carle M.

1987-01-01

Moses Rock dike is a Tertiary diatreme containing serpentinized ultramafic microbreccia (SUM). Field evidence indicates the SUM was emplaced first followed by breccias derived from the Permian strata exposed in the walls of the diatreme and finally by complex breccias containing basement and mantle derived rocks. SUM is found primarily dispersed throughout the matrix of the diatreme. Moses Rock dike was examined with Airborne Imaging Spectrometer (AIS) to map the distribution and excess of SUM in the matrix and to better understand the nature of the eruption which formed this explosive volcanic feature. AIS data was calibrated by dividing the suite of AIS data by data from an internal standard area and then multiplying this relative reflectance data by the absolute bidirectional reflectance of a selected sample from the standard area which was measured in the lab. From the calibrated AIS data the minerals serpentine, gypsum, and illite as well as desert varnish and the lithologies SUM and other sandstones were identified. SUM distribution and abundance in the matrix of the diatreme were examined in detail and two distinct styles of SUM dispersion were observed. The two styles are discussed in detail.

First-principles study of MoS2 and MoSe2 nanoclusters in the framework of evolutionary algorithm and density functional theory

NASA Astrophysics Data System (ADS)

Hashemi, Zohreh; Rafiezadeh, Shohreh; Hafizi, Roohollah; Hashemifar, S. Javad; Akbarzadeh, Hadi

2018-04-01

Evolutionary algorithm is combined with full-potential ab initio calculations to investigate conformational space of (MoS2)n and (MoSe2)n (n = 1-10) nanoclusters and to identify the lowest energy structural isomers of these systems. It is argued that within both BLYP and PBE functionals, these nanoclusters favor sandwiched planar configurations, similar to their ideal planar sheets. The second order difference in total energy (Δ2 E) of the lowest energy isomers is computed to estimate the abundance of the clusters at different sizes and to determine the magic sizes of (MoS2)n and (MoSe2)n nanoclusters. In order to investigate the electronic properties of nanoclusters, their energy gap is calculated by several methods, including hybrid functionals (B3LYP and PBE0), GW approach, and Δ scf method. At the end, the vibrational modes of the lowest lying isomers are calculated by using the force constants method and the IR active modes of the systems are identified. The vibrational spectra are used to calculate the Helmholtz free energy of the systems and then to investigate abundance of the nanoclusters at finite temperatures.

Probing the Interlayer Exciton Physics in a MoS2/MoSe2/MoS2 van der Waals Heterostructure.

PubMed

Baranowski, M; Surrente, A; Klopotowski, L; Urban, J M; Zhang, N; Maude, D K; Wiwatowski, K; Mackowski, S; Kung, Y C; Dumcenco, D; Kis, A; Plochocka, P

2017-10-11

Stacking atomic monolayers of semiconducting transition metal dichalcogenides (TMDs) has emerged as an effective way to engineer their properties. In principle, the staggered band alignment of TMD heterostructures should result in the formation of interlayer excitons with long lifetimes and robust valley polarization. However, these features have been observed simultaneously only in MoSe 2 /WSe 2 heterostructures. Here we report on the observation of long-lived interlayer exciton emission in a MoS 2 /MoSe 2 /MoS 2 trilayer van der Waals heterostructure. The interlayer nature of the observed transition is confirmed by photoluminescence spectroscopy, as well as by analyzing the temporal, excitation power, and temperature dependence of the interlayer emission peak. The observed complex photoluminescence dynamics suggests the presence of quasi-degenerate momentum-direct and momentum-indirect bandgaps. We show that circularly polarized optical pumping results in long-lived valley polarization of interlayer exciton. Intriguingly, the interlayer exciton photoluminescence has helicity opposite to the excitation. Our results show that through a careful choice of the TMDs forming the van der Waals heterostructure it is possible to control the circular polarization of the interlayer exciton emission.

Lattice structures and electronic properties of MO/MoSe2 interface from first-principles calculations

NASA Astrophysics Data System (ADS)

Zhang, Yu; Tang, Fu-Ling; Xue, Hong-Tao; Lu, Wen-Jiang; Liu, Jiang-Fei; Huang, Min

2015-02-01

Using first-principles plane-wave calculations within density functional theory, we theoretically studied the atomic structure, bonding energy and electronic properties of the perfect Mo (110)/MoSe2 (100) interface with a lattice mismatch less than 4.2%. Compared with the perfect structure, the interface is somewhat relaxed, and its atomic positions and bond lengths change slightly. The calculated interface bonding energy is about -1.2 J/m2, indicating that this interface is very stable. The MoSe2 layer on the interface has some interface states near the Fermi level, the interface states are mainly caused by Mo 4d orbitals, while the Se atom almost have no contribution. On the interface, Mo-5s and Se-4p orbitals hybridize at about -6.5 to -5.0 eV, and Mo-4d and Se-4p orbitals hybridize at about -5.0 to -1.0 eV. These hybridizations greatly improve the bonding ability of Mo and Se atom in the interface. By Bader charge analysis, we find electron redistribution near the interface which promotes the bonding of the Mo and MoSe2 layer.

Stability of direct band gap under mechanical strains for monolayer MoS2, MoSe2, WS2 and WSe2

NASA Astrophysics Data System (ADS)

Deng, Shuo; Li, Lijie; Li, Min

2018-07-01

Single layer transition-metal dichalcogenides materials (MoS2, MoSe2, WS2 and WSe2) are investigated using the first-principles method with the emphasis on their responses to mechanical strains. All these materials display the direct band gap under a certain range of strains from compressive to tensile (stable range). We have found that this stable range is different for these materials. Through studying on their mechanical properties again using the first-principles approach, it is unveiled that this stable strain range is determined by the Young's modulus. More analysis on strains induced electronic band gap properties have also been conducted.

[The human body in Michelangelo's Moses].

PubMed

Figueroa, Gustavo

2013-10-01

What grips us so powerfully to a work of art is the artist's intention, if he succeeds to express it in his work and we are able to understand it. Michelangelo's Moses established the essential structures of an animate organism and the embodiment of consciousness in the world. Since the body is an expressive unit, it is possible to reconstruct a highly feasible sequence of movements that might have preceded the moment caught in the statue. It is an expression of the highest ideal of mental and spiritual achievement through the controlled tension between action and restraint. The phenomenon of embodiment and feeling the body as own is the basis of concrete human existence.

Ambipolar transport in CVD grown MoSe2 monolayer using an ionic liquid gel gate dielectric

NASA Astrophysics Data System (ADS)

Ortiz, Deliris N.; Ramos, Idalia; Pinto, Nicholas J.; Zhao, Meng-Qiang; Kumar, Vinayak; Johnson, A. T. Charlie

2018-03-01

CVD grown MoSe2 monolayers were electrically characterized at room temperature in a field effect transistor (FET) configuration using an ionic liquid (IL) as the gate dielectric. During the growth, instead of using MoO3 powder, ammonium heptamolybdate was used for better Mo control of the source and sodium cholate added for lager MoSe2 growth areas. In addition, a high specific capacitance (˜7 μF/cm2) IL was used as the gate dielectric to significantly reduce the operating voltage. The device exhibited ambipolar charge transport at low voltages with enhanced parameters during n- and p-FET operation. IL gating thins the Schottky barrier at the metal/semiconductor interface permitting efficient charge injection into the channel and reduces the effects of contact resistance on device performance. The large specific capacitance of the IL was also responsible for a much higher induced charge density compared to the standard SiO2 dielectric. The device was successfully tested as an inverter with a gain of ˜2. Using a common metal for contacts simplifies fabrication of this ambipolar device, and the possibility of radiative recombination of holes and electrons could further extend its use in low power optoelectronic applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edward Moses

The National Ignition Facility, the world's largest laser system, was dedicated at a ceremony on May 29, 2009 at Lawrence Livermore National Laboratory. These are the remarks by NIF Director Edward Moses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, Colin M.; Yu, Hongyi; Jones, Aaron M.

In monolayer semiconductor transition metal dichalcogenides, the exciton–phonon interaction strongly affects the photocarrier dynamics. Here, we report on an unusual oscillatory enhancement of the neutral exciton photoluminescence with the excitation laser frequency in monolayer MoSe 2. The frequency of oscillation matches that of the M-point longitudinal acoustic phonon, LA(M), suggesting the significance of zone-edge acoustic phonons and hence the deformation potential in exciton-phonon coupling in MoSe 2. Moreover, oscillatory behavior is observed in the steady-state emission linewidth and in time-resolved PLE data, which reveals variation with excitation energy in the exciton lifetime. These results clearly expose the key role playedmore » by phonons in the exciton formation and relaxation dynamics of two-dimensional van der Waals semiconductors.« less

Moses Maimonides: medieval physician and scholar.

PubMed

Simon, S R

1999-09-13

Moses Maimonides (1135-1204), physician and philosopher, was the greatest Jewish thinker of the Middle Ages. Faced with a life of persecution, exile, and tragedy, Maimonides overcame obstacles to become the leading physician in his era, a clinician whose skills were sought across continents. Despite long days caring for patients, Maimonides wrote extensively about both medicine and philosophy. His medical works span all topics of clinical medicine and reflect rational thinking and an understanding of the relationship between mind and body. Well known for his philosophical writings, such as The Guide for the Perplexed, Maimonides codified Jewish law and revolutionized Jewish thinking. This review of his life and achievements provides insight into the world of a remarkable 12th-century physician and may offer valuable lessons for physicians today.

Anomalous scaling of stochastic processes and the Moses effect

NASA Astrophysics Data System (ADS)

Chen, Lijian; Bassler, Kevin E.; McCauley, Joseph L.; Gunaratne, Gemunu H.

2017-04-01

The state of a stochastic process evolving over a time t is typically assumed to lie on a normal distribution whose width scales like t1/2. However, processes in which the probability distribution is not normal and the scaling exponent differs from 1/2 are known. The search for possible origins of such "anomalous" scaling and approaches to quantify them are the motivations for the work reported here. In processes with stationary increments, where the stochastic process is time-independent, autocorrelations between increments and infinite variance of increments can cause anomalous scaling. These sources have been referred to as the Joseph effect and the Noah effect, respectively. If the increments are nonstationary, then scaling of increments with t can also lead to anomalous scaling, a mechanism we refer to as the Moses effect. Scaling exponents quantifying the three effects are defined and related to the Hurst exponent that characterizes the overall scaling of the stochastic process. Methods of time series analysis that enable accurate independent measurement of each exponent are presented. Simple stochastic processes are used to illustrate each effect. Intraday financial time series data are analyzed, revealing that their anomalous scaling is due only to the Moses effect. In the context of financial market data, we reiterate that the Joseph exponent, not the Hurst exponent, is the appropriate measure to test the efficient market hypothesis.

Precepts of community health and hygiene from the Holy Bible.

PubMed

Subhaktha, P K J P; Prasad, P V V; Narayana, A

2007-01-01

Every Society, in its unending process of evolution, devises its own methods of survival in ethical, medical and emotional aspects. The urge for good and healthy living, the desire for longevity of life are not only inherent but also largely evident in all the societies right from the time of its primitivity. Jews are a wonder community. Though negligible in numbers, they managed to win 17.5% of noble prizes announced so far. Besides, almost all the major inventions in the world are by Jews. This despite the years of persecution and trials the community was subjected to in the history. The pages of the human history are smeared with the blood patches of the Jews in the hands of oppressors for several centuries. Apart from the fact that theirs is the community chosen specially by God, the intellectual prowess and tenacity of the Jewish community basically stems from the discipline and dietary code they received from their leader Moses in wilderness. Jewish nation was conceived in the vision of their patriarch Abraham but in fact, born on the night they left as slaves from Egypt for good under the dynamic leadership of Moses. Mosaic code for all aspects of life has made Jews or Israelites what they are today. A modest effort is being made in this article to trace their community's health and hygiene social behavioral precepts as given by Moses.

Anomalous scaling of stochastic processes and the Moses effect.

PubMed

Chen, Lijian; Bassler, Kevin E; McCauley, Joseph L; Gunaratne, Gemunu H

2017-04-01

The state of a stochastic process evolving over a time t is typically assumed to lie on a normal distribution whose width scales like t^{1/2}. However, processes in which the probability distribution is not normal and the scaling exponent differs from 1/2 are known. The search for possible origins of such "anomalous" scaling and approaches to quantify them are the motivations for the work reported here. In processes with stationary increments, where the stochastic process is time-independent, autocorrelations between increments and infinite variance of increments can cause anomalous scaling. These sources have been referred to as the Joseph effect and the Noah effect, respectively. If the increments are nonstationary, then scaling of increments with t can also lead to anomalous scaling, a mechanism we refer to as the Moses effect. Scaling exponents quantifying the three effects are defined and related to the Hurst exponent that characterizes the overall scaling of the stochastic process. Methods of time series analysis that enable accurate independent measurement of each exponent are presented. Simple stochastic processes are used to illustrate each effect. Intraday financial time series data are analyzed, revealing that their anomalous scaling is due only to the Moses effect. In the context of financial market data, we reiterate that the Joseph exponent, not the Hurst exponent, is the appropriate measure to test the efficient market hypothesis.

Global change and relative sea level rise at Venice: what impact in term of flooding

NASA Astrophysics Data System (ADS)

Carbognin, Laura; Teatini, Pietro; Tomasin, Alberto; Tosi, Luigi

2010-11-01

Relative sea level rise (RSLR) due to climate change and geodynamics represents the main threat for the survival of Venice, emerging today only 90 cm above the Northern Adriatic mean sea level (msl). The 25 cm RSLR occurred over the 20th century, consisting of about 12 cm of land subsidence and 13 cm of sea level rise, has increased the flood frequency by more than seven times with severe damages to the urban heritage. Reasonable forecasts of the RSLR expected to the century end must be investigated to assess the suitability of the Mo.S.E. project planned for the city safeguarding, i.e., the closure of the lagoon inlets by mobile barriers. Here we consider three RSLR scenarios as resulting from the past sea level rise recorded in the Northern Adriatic Sea, the IPCC mid-range A1B scenario, and the expected land subsidence. Available sea level measurements show that more than 5 decades are required to compute a meaningful eustatic trend, due to pseudo-cyclic 7-8 year long fluctuations. The period from 1890 to 2007 is characterized by an average rate of 0.12 ± 0.01 cm/year. We demonstrate that linear regression is the most suitable model to represent the eustatic process over these 117 year. Concerning subsidence, at present Venice is sinking due to natural causes at 0.05 cm/year. The RSLR is expected to range between 17 and 53 cm by 2100, and its repercussions in terms of flooding frequency are associated here to each scenario. In particular, the frequency of tides higher than 110 cm, i.e., the value above which the gates would close the lagoon to the sea, will increase from the nowadays 4 times per year to a range between 20 and 250. These projections provide a large spread of possible conditions concerning the survival of Venice, from a moderate nuisance to an intolerable aggression. Hence, complementary solutions to Mo.S.E. may well be investigated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edward Moses

The National Ignition Facility, the world's largest laser system, was dedicated at a ceremony on May 29, 2009 at Lawrence Livermore National Laboratory. These are the concluding remarks by NIF Director Edward Moses, and a brief video presentation.

Effect of Sn Content in a CuSnZn Metal Precursor on Formation of MoSe2 Film during Selenization in Se+SnSe Vapor

PubMed Central

Yao, Liyong; Ao, Jianping; Jeng, Ming-Jer; Bi, Jinlian; Gao, Shoushuai; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Chang, Liann-Be

2016-01-01

The preparation of Cu2ZnSnSe4 (CZTSe) thin films by the selenization of an electrodeposited copper–tin–zinc (CuSnZn) precursor with various Sn contents in low-pressure Se+SnSex vapor was studied. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) measurements revealed that the Sn content of the precursor that is used in selenization in a low-pressure Se+SnSex vapor atmosphere only slightly affects the elemental composition of the formed CZTSe films. However, the Sn content of the precursor significantly affects the grain size and surface morphology of CZTSe films. A metal precursor with a very Sn-poor composition produces CZTSe films with large grains and a rough surface, while a metal precursor with a very Sn-rich composition procures CZTSe films with small grains and a compact surface. X-ray diffraction (XRD) and SEM revealed that the metal precursor with a Sn-rich composition can grow a thicker MoSe2 thin film at CZTSe/Mo interface than one with a Sn-poor composition, possibly because excess Sn in the precursor may catalyze the formation of MoSe2 thin film. A CZTSe solar cell with an efficiency of 7.94%was realized by using an electrodeposited metal precursor with a Sn/Cu ratio of 0.5 in selenization in a low-pressure Se+SnSex vapor. PMID:28773366

The Moses Mabhida Medical Plan: medical care planning and execution at a FIFA2010 stadium; the Durban experience.

PubMed

Hardcastle, Timothy C; Naidoo, Mergan; Samlal, Sanjay; Naidoo, Morgambery; Larsen, Timothy; Mabasu, Muzi; Ngema, Sibongiseni

2010-01-01

This paper aims to outline the medical services provided at the Moses Mabhida Stadium, Durban, South Africa for the Fédération Internationale de Football Association (FIFA) 2010 Soccer World Cup and audit the clinical services delivered to persons seeking medical assistance. Descriptive report of the medical facilities at the Moses Mabhida Stadium including the staff deployment. Retrospective data review of medical incident reports from the Stadium Medical Team. Medical staffing exceeded the local norms and was satisfactory to provide rapid intervention for all incoming patients. Senior medical presence decreased the transport to hospital rate (TTHR). A total of 316 spectators or support staff were treated during the seven matches played at the stadium. The majority of patients were male (60%), mostly of local origin, with mostly minor complaints that were treated and discharged (88.2% Green codes). The most common complaints were headache, abdominal disorders, and soft-tissue injuries. One fatality was recorded. The patient presentation rate (PPR) was 0.66/10,000 and the TTHR was overall 4.1% of all treated patients (0.027/10,000 spectators). There was little evidence to guide medical planning for staffing from the FIFA governing body. Most patients are treated and released in accordance with international literature, leading to low TTHR rates, while PPR was in line with international experience. Headache was the most common medical complaint. The blowing of Vuvuzelas(®) may have influenced the high headache rate.

The Moses Mabhida Medical Plan: medical care planning and execution at a FIFA2010 stadium; the Durban experience

PubMed Central

Hardcastle, Timothy C; Naidoo, Mergan; Samlal, Sanjay; Naidoo, Morgambery; Larsen, Timothy; Mabasu, Muzi; Ngema, Sibongiseni

2010-01-01

Aim This paper aims to outline the medical services provided at the Moses Mabhida Stadium, Durban, South Africa for the Fédération Internationale de Football Association (FIFA) 2010 Soccer World Cup and audit the clinical services delivered to persons seeking medical assistance. Methods Descriptive report of the medical facilities at the Moses Mabhida Stadium including the staff deployment. Retrospective data review of medical incident reports from the Stadium Medical Team. Results Medical staffing exceeded the local norms and was satisfactory to provide rapid intervention for all incoming patients. Senior medical presence decreased the transport to hospital rate (TTHR). A total of 316 spectators or support staff were treated during the seven matches played at the stadium. The majority of patients were male (60%), mostly of local origin, with mostly minor complaints that were treated and discharged (88.2% Green codes). The most common complaints were headache, abdominal disorders, and soft-tissue injuries. One fatality was recorded. The patient presentation rate (PPR) was 0.66/10,000 and the TTHR was overall 4.1% of all treated patients (0.027/10,000 spectators). Conclusion There was little evidence to guide medical planning for staffing from the FIFA governing body. Most patients are treated and released in accordance with international literature, leading to low TTHR rates, while PPR was in line with international experience. Headache was the most common medical complaint. The blowing of Vuvuzelas® may have influenced the high headache rate. PMID:27147844

Star Power on Earth: Path to Clean Energy Future

ScienceCinema

Ed Moses

2017-12-09

Lawrence Livermore National Laboratory's "Science on Saturday" lecture series presents Ed Moses, Director of the National Ignition Facility, discussing the world's largest laser system and its potential impact on society's upcoming energy needs.

76 FR 55667 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

... technology; evaluating exemption requests and exclusion notices; targeting compliance inspections; and...: September 1, 2011. John Moses, Director, Collection Strategies Division. [FR Doc. 2011-22991 Filed 9-7-11; 8...

12-NIF Dedication: Concluding remarks and video

ScienceCinema

Edward Moses

2017-12-09

The National Ignition Facility, the world's largest laser system, was dedicated at a ceremony on May 29, 2009 at Lawrence Livermore National Laboratory. These are the concluding remarks by NIF Director Edward Moses, and a brief video presentation.

Large effective mass and interaction-enhanced Zeeman splitting of K -valley electrons in MoSe2

NASA Astrophysics Data System (ADS)

Larentis, Stefano; Movva, Hema C. P.; Fallahazad, Babak; Kim, Kyounghwan; Behroozi, Armand; Taniguchi, Takashi; Watanabe, Kenji; Banerjee, Sanjay K.; Tutuc, Emanuel

2018-05-01

We study the magnetotransport of high-mobility electrons in monolayer and bilayer MoSe2, which show Shubnikov-de Haas (SdH) oscillations and quantum Hall states in high magnetic fields. An electron effective mass of 0.8 me is extracted from the SdH oscillations' temperature dependence; me is the bare electron mass. At a fixed electron density the longitudinal resistance shows minima at filling factors (FFs) that are either predominantly odd, or predominantly even, with a parity that changes as the density is tuned. The SdH oscillations are insensitive to an in-plane magnetic field, consistent with an out-of-plane spin orientation of electrons at the K point. We attribute the FF parity transitions to an interaction enhancement of the Zeeman energy as the density is reduced, resulting in an increased Zeeman-to-cyclotron energy ratio.

Population Pulsation Resonances of Excitons in Monolayer MoSe 2 with Sub-1 μeV Linewidths

DOE PAGES

Schaibley, John R.; Karin, Todd; Yu, Hongyi; ...

2015-04-01

Monolayer transition metal dichalcogenides, a new class of atomically thin semiconductors, possess optically coupled 2D valley excitons. The nature of exciton relaxation in these systems is currently poorly understood. In this paper, we investigate exciton relaxation in monolayer MoSe 2 using polarization-resolved coherent nonlinear optical spectroscopy with high spectral resolution. We report strikingly narrow population pulsation resonances with two different characteristic linewidths of 1 and <0.2 μeV at low temperature. These linewidths are more than 3 orders of magnitude narrower than the photoluminescence and absorption linewidth, and indicate that a component of the exciton relaxation dynamics occurs on time scalesmore » longer than 1 ns. Finally, the ultranarrow resonance (<0.2 μeV) emerges with increasing excitation intensity, and implies the existence of a long-lived state whose lifetime exceeds 6 ns.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keyshar, Kunttal; Berg, Morgann; Zhang, Xiang

Here, the values of the ionization energies of transition metal dichalcogenides (TMDs) are needed to assess their potential usefulness in semiconductor heterojunctions for high-performance optoelectronics. Here, we report on the systematic determination of ionization energies for three prototypical TMD monolayers (MoSe 2, WS 2, and MoS 2) on SiO 2 using photoemission electron microscopy with deep ultraviolet illumination. The ionization energy displays a progressive decrease from MoS 2, to WS 2, to MoSe 2, in agreement with predictions of density functional theory calculations. Combined with the measured energy positions of the valence band edge at the Brillouin zone center, wemore » deduce that, in the absence of interlayer coupling, a vertical heterojunction comprising any of the three TMD monolayers would form a staggered (type-II) band alignment. This band alignment could give rise to long-lived interlayer excitons that are potentially useful for valleytronics or efficient electron–hole separation in photovoltaics.« less

Nanoscale deformation and friction characteristics of atomically thin WSe2 and heterostructure using nanoscratch and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Manimunda, P.; Nakanishi, Y.; Jaques, Y. M.; Susarla, S.; Woellner, C. F.; Bhowmick, S.; Asif, S. A. S.; Galvão, D. S.; Tiwary, C. S.; Ajayan, P. M.

2017-12-01

2D transition metals di-selenides are attracting a lot of attention due to their interesting optical, chemical and electronics properties. Here, the deformation characteristics of monolayer, multi- layer WSe2 and its heterostructure with MoSe2 were investigated using a new technique that combines nanoscratch and Raman spectroscopy. The 2D monolayer WSe2 showed anisotropy in deformation. Effect of number of WSe2 layers on friction characteristics were explored in detail. Experimental observations were further supported by MD simulations. Raman spectra recorded from the scratched regions showed strain induced degeneracy splitting. Further nano-scale scratch tests were extended to MoSe2-WSe2 lateral heterostructures. Effect of deformation on lateral hetero junctions were further analysed using PL and Raman spectroscopy. This new technique is completely general and can be applied to study other 2D materials.

Facile fabrication of CNTs@C@MoSe2@Se hybrids with amorphous structure for high performance anode in lithium-ion batteries.

PubMed

Jin, Rencheng; Cui, Yuming; Wang, Qingyao; Li, Guihua

2017-12-15

Amorphous MoSe 2 and Se anchored on amorphous carbon coated multiwalled carbon nanotubes (CNTs@C@MoSe 2 @Se) have been synthesized by a facile solvothermal strategy. The one dimensional CNTs@C@MoSe 2 @Se can effectively buffer the volume variation, prohibit the aggregation and facilitate electron and ion transport throughout the electrode. Furthermore, the combination of MoSe 2 and Se also provides buffer spaces for the volumetric change during cycling. Thus, the obtained CNTs@C@MoSe 2 @Se hybrids display the enhanced cycle stability and excellent high rate capacity. The reversible capacity of 1010mAhg -1 can be achieved after 100 cycles at the current density of 0.1Ag -1 . Even after 500 cycles, a reversible capacity of 508mAhg -1 is still retained at 5Ag -1 . Copyright © 2017 Elsevier Inc. All rights reserved.

Observation of Exciton-Exciton Interaction Mediated Valley Depolarization in Monolayer MoSe2.

PubMed

Mahmood, Fahad; Alpichshev, Zhanybek; Lee, Yi-Hsien; Kong, Jing; Gedik, Nuh

2018-01-10

The valley pseudospin in monolayer transition metal dichalcogenides (TMDs) has been proposed as a new way to manipulate information in various optoelectronic devices. This relies on a large valley polarization that remains stable over long time scales (hundreds of nanoseconds). However, time-resolved measurements report valley lifetimes of only a few picoseconds. This has been attributed to mechanisms such as phonon-mediated intervalley scattering and a precession of the valley pseudospin through electron-hole exchange. Here we use transient spin grating to directly measure the valley depolarization lifetime in monolayer MoSe 2 . We find a fast valley decay rate that scales linearly with the excitation density at different temperatures. This establishes the presence of strong exciton-exciton Coulomb exchange interactions enhancing the valley depolarization. Our work highlights the microscopic processes inhibiting the efficient use of the exciton valley pseudospin in monolayer TMDs.

Intrinsic coherence time of trions in monolayer MoSe2 measured via two-dimensional coherent spectroscopy

NASA Astrophysics Data System (ADS)

Titze, Michael; Li, Bo; Zhang, Xiang; Ajayan, Pulickel M.; Li, Hebin

2018-05-01

Quantum coherence and its dynamics in monolayer transition metal dichalcogenides (TMDs) are essential information to fully control valley pseudospin for valleytronics applications. Experimental understanding of coherence dephasing dynamics has been limited for excitons and largely unexplored for trions in monolayer TMDs. Here we use optical two-dimensional coherent spectroscopy to measure the trion coherence dephasing time in monolayer MoSe2 by analyzing the homogeneous linewidth. An intrinsic coherence time of 182 fs is extrapolated from the excitation density and temperature dependence measurement. The results show that trion-trion and trion-phonon interactions strongly affect the coherence dephasing time, while the intrinsic coherence time at zero excitation and zero temperature is primarily limited by the pure dephasing due to defect states. Our experiment also confirms optical two-dimensional coherent spectroscopy as a reliable technique for studying valley quantum dynamics in two-dimensional layered materials.

Two-dimensional GaSe/MoSe2 misfit bilayer heterojunctions by van der Waals epitaxy.

PubMed

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; Huang, Bing; Puretzky, Alexander A; Ma, Cheng; Wang, Kai; Zhou, Wu; Pantelides, Sokrates T; Chi, Miaofang; Kravchenko, Ivan; Fowlkes, Jason; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

2016-04-01

Two-dimensional (2D) heterostructures hold the promise for future atomically thin electronics and optoelectronics because of their diverse functionalities. Although heterostructures consisting of different 2D materials with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) epitaxy, constructing heterostructures from layered semiconductors with large lattice misfits remains challenging. We report the growth of 2D GaSe/MoSe2 heterostructures with a large lattice misfit using two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientation between the two layers, forming a periodic superlattice. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe2 monolayer domains in lateral GaSe/MoSe2 heterostructures, GaSe monolayers are found to overgrow MoSe2 during CVD, forming a stripe of vertically stacked vdW heterostructures at the crystal interface. Such vertically stacked vdW GaSe/MoSe2 heterostructures are shown to form p-n junctions with effective transport and separation of photogenerated charge carriers between layers, resulting in a gate-tunable photovoltaic response. These GaSe/MoSe2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.

Two-dimensional GaSe/MoSe2 misfit bilayer heterojunctions by van der Waals epitaxy

PubMed Central

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; Huang, Bing; Puretzky, Alexander A.; Ma, Cheng; Wang, Kai; Zhou, Wu; Pantelides, Sokrates T.; Chi, Miaofang; Kravchenko, Ivan; Fowlkes, Jason; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

2016-01-01

Two-dimensional (2D) heterostructures hold the promise for future atomically thin electronics and optoelectronics because of their diverse functionalities. Although heterostructures consisting of different 2D materials with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) epitaxy, constructing heterostructures from layered semiconductors with large lattice misfits remains challenging. We report the growth of 2D GaSe/MoSe2 heterostructures with a large lattice misfit using two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientation between the two layers, forming a periodic superlattice. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe2 monolayer domains in lateral GaSe/MoSe2 heterostructures, GaSe monolayers are found to overgrow MoSe2 during CVD, forming a stripe of vertically stacked vdW heterostructures at the crystal interface. Such vertically stacked vdW GaSe/MoSe2 heterostructures are shown to form p-n junctions with effective transport and separation of photogenerated charge carriers between layers, resulting in a gate-tunable photovoltaic response. These GaSe/MoSe2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells. PMID:27152356

77 FR 70747 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-27

... Statistics to calculate burden costs. Additionally, there is an increase in the total number of annual responses due to a mathematical correction made in the previous ICR. John Moses, Director, Collection...

2. Photocopy of measured drawing (original drawing in the possession ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Photocopy of measured drawing (original drawing in the possession of Beinecke Rare Books Library, Yale University) Henry Austin, architect, 1850 NORTHEAST ELEVATION - Moses Yale Beach House, 86 North Main Street, Wallingford, New Haven County, CT

1. Photocopy of measured drawing (original drawing in the possession ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of measured drawing (original drawing in the possession of Beinecke Rare Books Library, Yale University) Henry Austin, architect, 1850 SOUTHEAST (FRONT) ELEVATION - Moses Yale Beach House, 86 North Main Street, Wallingford, New Haven County, CT

Rome Laboratory Journal, 1992

DTIC Science & Technology

1992-01-01

89 Suryadevara V. Babu, Raghunath Padiyath, Moses David. and Lois Walsh THREE-DIMENSIONAL MULTIREGION Sa SOLUTIONS OF THE...is built by simple sm -RC time constant analysis of thle buts, then thle discrete im- inispection of the bus and then itiverted to produice the driving

Face Recognition From One Example View.

DTIC Science & Technology

1995-09-01

Proceedings, International Workshop on Automatic Face- and Gesture-Recognition, pages 248{253, Zurich, 1995. [32] Yael Moses, Shimon Ullman, and Shimon...recognition. Journal of Cognitive Neuroscience, 3(1):71{86, 1991. [49] Shimon Ullman and Ronen Basri. Recognition by linear combinations of models

Cross-Cultural HRD. Symposium.

ERIC Educational Resources Information Center

2002

The first of three papers from this symposium on cross-cultural human resource development (HRD), "Determinants of Supply of Technical Training Opportunities for Human Capital Development in Kenya" (Moses Waithanji Ngware, Fredrick Muyia Nafukho) reports findings from interviews of technical training institute department heads in Kenya…

Two-dimensional GaSe/MoSe 2 misfit bilayer heterojunctions by van der Waals epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xufan; Lin, Ming-Wei; Lin, Junhao

Two-dimensional (2D) heterostructures hold the promise for future atomically-thin electronics and optoelectronics due to their diverse functionalities. While heterostructures consisting of different transition metal dichacolgenide monolayers with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) or edge epitaxy, constructing heterostructures from monolayers of layered semiconductors with large lattice misfits still remains challenging. Here, we report the growth of monolayer GaSe/MoSe 2 heterostructures with large lattice misfit by two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe 2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientationmore » between the two layers, forming an incommensurate vdW heterostructure. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe 2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe 2 monolayer domains in lateral GaSe/MoSe 2 heterostructures, GaSe monolayers are found to overgrow MoSe 2 during CVD, forming a stripe of vertically stacked vdW heterostructure at the crystal interface. Such vertically-stacked vdW GaSe/MoSe 2 heterostructures are shown to form p-n junctions with effective transport and separation of photo-generated charge carriers between layers, resulting in a gate-tunable photovoltaic response. In conclusion, these GaSe/MoSe 2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.« less

Ultrafast non-radiative dynamics of atomically thin MoSe 2

DOE PAGES

Lin, Ming -Fu; Kochat, Vidya; Krishnamoorthy, Aravind; ...

2017-10-17

Non-radiative energy dissipation in photoexcited materials and resulting atomic dynamics provide a promising pathway to induce structural phase transitions in two-dimensional materials. However, these dynamics have not been explored in detail thus far because of incomplete understanding of interaction between the electronic and atomic degrees of freedom, and a lack of direct experimental methods to quantify real-time atomic motion and lattice temperature. Here, we explore the ultrafast conversion of photoenergy to lattice vibrations in a model bi-layered semiconductor, molybdenum diselenide, MoSe 2. Specifically, we characterize sub-picosecond lattice dynamics initiated by the optical excitation of electronic charge carriers in the highmore » electron-hole plasma density regime. Our results focuses on the first ten picosecond dynamics subsequent to photoexcitation before the onset of heat transfer to the substrate, which occurs on a ~100 picosecond time scale. Photoinduced atomic motion is probed by measuring the time dependent Bragg diffraction of a delayed mega-electronvolt femtosecond electron beam. Transient lattice temperatures are characterized through measurement of Bragg peak intensities and calculation of the Debye-Waller factor (DWF). These measurements show a sub-picosecond decay of Bragg diffraction and a correspondingly rapid rise in lattice temperatures. We estimate a high quantum yield for the conversion of excited charge carrier energy to lattice motion under our experimental conditions, indicative of a strong electron-phonon interaction. First principles nonadiabatic quantum molecular dynamics simulations (NAQMD) on electronically excited MoSe 2 bilayers reproduce the observed picosecond-scale increase in lattice temperature and ultrafast conversion of photoenergy to lattice vibrations. Calculation of excited-state phonon dispersion curves suggests that softened vibrational modes in the excited state are involved in efficient and rapid energy transfer between the electronic system and the lattice.« less

Ultrafast non-radiative dynamics of atomically thin MoSe 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Ming -Fu; Kochat, Vidya; Krishnamoorthy, Aravind

Non-radiative energy dissipation in photoexcited materials and resulting atomic dynamics provide a promising pathway to induce structural phase transitions in two-dimensional materials. However, these dynamics have not been explored in detail thus far because of incomplete understanding of interaction between the electronic and atomic degrees of freedom, and a lack of direct experimental methods to quantify real-time atomic motion and lattice temperature. Here, we explore the ultrafast conversion of photoenergy to lattice vibrations in a model bi-layered semiconductor, molybdenum diselenide, MoSe 2. Specifically, we characterize sub-picosecond lattice dynamics initiated by the optical excitation of electronic charge carriers in the highmore » electron-hole plasma density regime. Our results focuses on the first ten picosecond dynamics subsequent to photoexcitation before the onset of heat transfer to the substrate, which occurs on a ~100 picosecond time scale. Photoinduced atomic motion is probed by measuring the time dependent Bragg diffraction of a delayed mega-electronvolt femtosecond electron beam. Transient lattice temperatures are characterized through measurement of Bragg peak intensities and calculation of the Debye-Waller factor (DWF). These measurements show a sub-picosecond decay of Bragg diffraction and a correspondingly rapid rise in lattice temperatures. We estimate a high quantum yield for the conversion of excited charge carrier energy to lattice motion under our experimental conditions, indicative of a strong electron-phonon interaction. First principles nonadiabatic quantum molecular dynamics simulations (NAQMD) on electronically excited MoSe 2 bilayers reproduce the observed picosecond-scale increase in lattice temperature and ultrafast conversion of photoenergy to lattice vibrations. Calculation of excited-state phonon dispersion curves suggests that softened vibrational modes in the excited state are involved in efficient and rapid energy transfer between the electronic system and the lattice.« less

Two-dimensional GaSe/MoSe 2 misfit bilayer heterojunctions by van der Waals epitaxy

DOE PAGES

Li, Xufan; Lin, Ming-Wei; Lin, Junhao; ...

2016-04-01

Two-dimensional (2D) heterostructures hold the promise for future atomically-thin electronics and optoelectronics due to their diverse functionalities. While heterostructures consisting of different transition metal dichacolgenide monolayers with well-matched lattices and novel physical properties have been successfully fabricated via van der Waals (vdW) or edge epitaxy, constructing heterostructures from monolayers of layered semiconductors with large lattice misfits still remains challenging. Here, we report the growth of monolayer GaSe/MoSe 2 heterostructures with large lattice misfit by two-step chemical vapor deposition (CVD). Both vertically stacked and lateral heterostructures are demonstrated. The vertically stacked GaSe/MoSe 2 heterostructures exhibit vdW epitaxy with well-aligned lattice orientationmore » between the two layers, forming an incommensurate vdW heterostructure. However, the lateral heterostructures exhibit no lateral epitaxial alignment at the interface between GaSe and MoSe 2 crystalline domains. Instead of a direct lateral connection at the boundary region where the same lattice orientation is observed between GaSe and MoSe 2 monolayer domains in lateral GaSe/MoSe 2 heterostructures, GaSe monolayers are found to overgrow MoSe 2 during CVD, forming a stripe of vertically stacked vdW heterostructure at the crystal interface. Such vertically-stacked vdW GaSe/MoSe 2 heterostructures are shown to form p-n junctions with effective transport and separation of photo-generated charge carriers between layers, resulting in a gate-tunable photovoltaic response. In conclusion, these GaSe/MoSe 2 vdW heterostructures should have applications as gate-tunable field-effect transistors, photodetectors, and solar cells.« less

Isoelectronic tungsten doping in monolayer MoSe 2 for carrier type modulation

DOE PAGES

Li, Xufan; Lin, Ming -Wei; Basile, Leonardo; ...

2016-07-06

Doping and alloying are effective ways to engineer the band structure and modulate the optoelectronic functionality of monolayer transition metal dichalcogenides (TMDs). In this work, we explore the synthesis and electronic properties of monolayer Mo 1-xW xSe 2 (0 < x < 0.18) alloys with almost 100% alloying degree. The isoelectronic substitutional doping of tungsten for molybdenum in the monolayer MoSe 2 is shown to suppress its intrinsically n-type conduction behavior, with p-type conduction gradually emerging to become dominant with increasing W concentration in the alloys. Atomic resolution Z-contrast electron microscopy show that W is shown to substitute directly formore » Mo without the introduction of noticeable vacancy or interstitial defects, however with randomly-distributed W-rich regions ~2 nm in diameter. Scanning tunneling microscopy/spectroscopy measurements reveal that these W-rich regions exhibit a local band structure with the valence band maximum (VBM) closer to the Fermi level as compared with the Mo-rich regions in the monolayer Mo 1-xW xSe 2 crystal. These localized upshifts of the VBM in the local band structure appear responsible for the overall p-type behavior observed for the monolayer Mo 1-xW xSe 2 crystals. Stacked monolayers of n-type MoSe 2 and p-type Mo 1-xW xSe 2 were demonstrated to form atomically thin, vertically stacked p n homojunctions with gate-tunable characteristics, which appear useful for future optoelectronic applications. Lastly, these results indicate that alloying with isoelectronic dopant atoms appears to be an effective and advantageous alternate strategy to doping or alloying with electron donors or acceptors in two-dimensional TMDs.« less

Fire Island National Seashore survey of walk-in visitors

DOT National Transportation Integrated Search

2005-04-30

The FINS Survey of Walk-in Visitors was conducted with the aim of determining how public access to the island can be improved. This survey obtained input from visitors who access the National Seashore on foot from nearby Robert Moses State Park on th...

Imaging exciton–polariton transport in MoSe2 waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, F.; Luan, Y.; Scott, M. E.

The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies1-4. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons5-9. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation length of the EPs is sensitive to the excitation photon energy and reaches over 12 μm. The polariton wavelength canmore » be conveniently altered from 600 nm down to 300 nm by controlling the waveguide thickness. Furthermore, we found an intriguing back-bending polariton dispersion close to the exciton resonance. The observed EPs in vdW semiconductors could be useful in future nanophotonic circuits operating in the near-infrared to visible spectral regions.« less

Imaging exciton–polariton transport in MoSe2 waveguides

DOE PAGES

Hu, F.; Luan, Y.; Scott, M. E.; ...

2017-05-08

The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies1-4. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons5-9. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation length of the EPs is sensitive to the excitation photon energy and reaches over 12 μm. The polariton wavelength canmore » be conveniently altered from 600 nm down to 300 nm by controlling the waveguide thickness. Furthermore, we found an intriguing back-bending polariton dispersion close to the exciton resonance. The observed EPs in vdW semiconductors could be useful in future nanophotonic circuits operating in the near-infrared to visible spectral regions.« less

Patterned arrays of lateral heterojunctions within monolayer two-dimensional semiconductors

DOE PAGES

Mahjouri-Samani, Masoud; Lin, Ming-Wei; Wang, Kai; ...

2015-07-22

The formation of semiconductor heterojunctions and their high density integration are foundations of modern electronics and optoelectronics. To enable two-dimensional (2D) crystalline semiconductors as building blocks in next generation electronics, developing methods to deterministically form lateral heterojunctions is crucial. Here we demonstrate a process strategy for the formation of lithographically-patterned lateral semiconducting heterojunctions within a single 2D crystal. E-beam lithography is used to pattern MoSe 2 monolayer crystals with SiO 2, and the exposed locations are selectively and totally converted to MoS 2 using pulsed laser deposition (PLD) of sulfur in order to form MoSe 2/MoS 2 heterojunctions in predefinedmore » patterns. The junctions and conversion process are characterized by atomically resolved scanning transmission electron microscopy, photoluminescence, and Raman spectroscopy. This demonstration of lateral semiconductor heterojunction arrays within a single 2D crystal is an essential step for the lateral integration of 2D semiconductor building blocks with different electronic and optoelectronic properties for high-density, ultrathin circuitry.« less

Study on photon transport problem based on the platform of molecular optical simulation environment.

PubMed

Peng, Kuan; Gao, Xinbo; Liang, Jimin; Qu, Xiaochao; Ren, Nunu; Chen, Xueli; Ma, Bin; Tian, Jie

2010-01-01

As an important molecular imaging modality, optical imaging has attracted increasing attention in the recent years. Since the physical experiment is usually complicated and expensive, research methods based on simulation platforms have obtained extensive attention. We developed a simulation platform named Molecular Optical Simulation Environment (MOSE) to simulate photon transport in both biological tissues and free space for optical imaging based on noncontact measurement. In this platform, Monte Carlo (MC) method and the hybrid radiosity-radiance theorem are used to simulate photon transport in biological tissues and free space, respectively, so both contact and noncontact measurement modes of optical imaging can be simulated properly. In addition, a parallelization strategy for MC method is employed to improve the computational efficiency. In this paper, we study the photon transport problems in both biological tissues and free space using MOSE. The results are compared with Tracepro, simplified spherical harmonics method (SP(n)), and physical measurement to verify the performance of our study method on both accuracy and efficiency.

Study on Photon Transport Problem Based on the Platform of Molecular Optical Simulation Environment

PubMed Central

Peng, Kuan; Gao, Xinbo; Liang, Jimin; Qu, Xiaochao; Ren, Nunu; Chen, Xueli; Ma, Bin; Tian, Jie

2010-01-01

As an important molecular imaging modality, optical imaging has attracted increasing attention in the recent years. Since the physical experiment is usually complicated and expensive, research methods based on simulation platforms have obtained extensive attention. We developed a simulation platform named Molecular Optical Simulation Environment (MOSE) to simulate photon transport in both biological tissues and free space for optical imaging based on noncontact measurement. In this platform, Monte Carlo (MC) method and the hybrid radiosity-radiance theorem are used to simulate photon transport in biological tissues and free space, respectively, so both contact and noncontact measurement modes of optical imaging can be simulated properly. In addition, a parallelization strategy for MC method is employed to improve the computational efficiency. In this paper, we study the photon transport problems in both biological tissues and free space using MOSE. The results are compared with Tracepro, simplified spherical harmonics method (S P n), and physical measurement to verify the performance of our study method on both accuracy and efficiency. PMID:20445737

Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating

PubMed Central

Shi, Wu; Ye, Jianting; Zhang, Yijin; Suzuki, Ryuji; Yoshida, Masaro; Miyazaki, Jun; Inoue, Naoko; Saito, Yu; Iwasa, Yoshihiro

2015-01-01

Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the least studied property in TMDs due to methodological difficulty accessing it in different TMD species. Here, we report the systematic study of superconductivity in MoSe2, MoTe2 and WS2 by ionic gating in different regimes. Electrostatic gating using ionic liquid was able to induce superconductivity in MoSe2 but not in MoTe2 because of inefficient electron accumulation limited by electronic band alignment. Alternative gating using KClO4/polyethylene glycol enabled a crossover from surface doping to bulk doping, which induced superconductivities in MoTe2 and WS2 electrochemically. These new varieties greatly enriched the TMD superconductor families and unveiled critical methodology to expand the capability of ionic gating to other materials. PMID:26235962

Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating.

PubMed

Shi, Wu; Ye, Jianting; Zhang, Yijin; Suzuki, Ryuji; Yoshida, Masaro; Miyazaki, Jun; Inoue, Naoko; Saito, Yu; Iwasa, Yoshihiro

2015-08-03

Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the least studied property in TMDs due to methodological difficulty accessing it in different TMD species. Here, we report the systematic study of superconductivity in MoSe2, MoTe2 and WS2 by ionic gating in different regimes. Electrostatic gating using ionic liquid was able to induce superconductivity in MoSe2 but not in MoTe2 because of inefficient electron accumulation limited by electronic band alignment. Alternative gating using KClO4/polyethylene glycol enabled a crossover from surface doping to bulk doping, which induced superconductivities in MoTe2 and WS2 electrochemically. These new varieties greatly enriched the TMD superconductor families and unveiled critical methodology to expand the capability of ionic gating to other materials.

Observation of long-lived interlayer excitons in monolayer MoSe 2–WSe 2 heterostructures

DOE PAGES

Rivera, Pasqual; Schaibley, John R.; Jones, Aaron M.; ...

2015-02-24

Van der Waals bound heterostructures constructed with two-dimensional materials, such as graphene, boron nitride and transition metal dichalcogenides, have sparked wide interest in both device physics and technologies at the two-dimensional limit. One highly coveted heterostructure is that of differing monolayer transition metal dichalcogenides with type-II band alignment, with bound electrons and holes localized in individual monolayers, that is, interlayer excitons. Here, we report the observation of interlayer excitons in monolayer MoSe 2–WSe 2 heterostructures by photoluminescence and photoluminescence excitation spectroscopy. The energy and luminescence intensity are highly tunable by an applied vertical gate voltage. Moreover, we measure an interlayermore » exciton lifetime of ~1.8 ns, an order of magnitude longer than intralayer excitons in monolayers. Ultimately, our work demonstrates optical pumping of interlayer electric polarization, which may provoke further exploration of interlayer exciton condensation, as well as new applications in two-dimensional lasers, light-emitting diodes and photovoltaic devices.« less

Nanoforging Single Layer MoSe 2 Through Defect Engineering with Focused Helium Ion Beams

DOE PAGES

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.; ...

2016-08-02

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe 2 locally, and decipher associated mechanisms at atomic level. We demonstrate He + beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and thereby increases the Young s modulus of elasticity. Furthermore, wemore » observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at room temperature. In conclusion, the approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.« less

Nanoforging Single Layer MoSe 2 Through Defect Engineering with Focused Helium Ion Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe 2 locally, and decipher associated mechanisms at atomic level. We demonstrate He + beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and thereby increases the Young s modulus of elasticity. Furthermore, wemore » observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at room temperature. In conclusion, the approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.« less

Nanoforging Single Layer MoSe2 Through Defect Engineering with Focused Helium Ion Beams

NASA Astrophysics Data System (ADS)

Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.; Stanford, Michael G.; Lin, Ming-Wei; Li, Xufan; Mahjouri-Samani, Masoud; Jesse, Stephen; Sumpter, Bobby G.; Kalinin, Sergei V.; Joy, David C.; Xiao, Kai; Belianinov, Alex; Ovchinnikova, Olga S.

2016-08-01

Development of devices and structures based on the layered 2D materials critically hinges on the capability to induce, control, and tailor the electronic, transport, and optoelectronic properties via defect engineering, much like doping strategies have enabled semiconductor electronics and forging enabled introduction the of iron age. Here, we demonstrate the use of a scanning helium ion microscope (HIM) for tailoring the functionality of single layer MoSe2 locally, and decipher associated mechanisms at the atomic level. We demonstrate He+ beam bombardment that locally creates vacancies, shifts the Fermi energy landscape and increases the Young’s modulus of elasticity. Furthermore, we observe for the first time, an increase in the B-exciton photoluminescence signal from the nanoforged regions at the room temperature. The approach for precise defect engineering demonstrated here opens opportunities for creating functional 2D optoelectronic devices with a wide range of customizable properties that include operating in the visible region.

Pressure induced metallization with absence of structural transition in layered molybdenum diselenide

DOE PAGES

Zhao, Zhao; Zhang, Haijun; Yuan, Hongtao; ...

2015-06-19

Layered transition-metal dichalcogenides have emerged as exciting material systems with atomically thin geometries and unique electronic properties. Pressure is a powerful tool for continuously tuning their crystal and electronic structures away from the pristine states. Here, we systematically investigated the pressurized behavior of MoSe 2 up to ~60 GPa using multiple experimental techniques and ab-initio calculations. MoSe 2 evolves from an anisotropic two-dimensional layered network to a three-dimensional structure without a structural transition, which is a complete contrast to MoS 2. The role of the chalcogenide anions in stabilizing different layered patterns is underscored by our layer sliding calculations. MoSemore » 2 possesses highly tunable transport properties under pressure, determined by the gradual narrowing of its band-gap followed by metallization. The continuous tuning of its electronic structure and band-gap in the range of visible light to infrared suggest possible energy-variable optoelectronics applications in pressurized transition-metal dichalcogenides.« less

Patterned arrays of lateral heterojunctions within monolayer two-dimensional semiconductors

PubMed Central

Mahjouri-Samani, Masoud; Lin, Ming-Wei; Wang, Kai; Lupini, Andrew R.; Lee, Jaekwang; Basile, Leonardo; Boulesbaa, Abdelaziz; Rouleau, Christopher M.; Puretzky, Alexander A.; Ivanov, Ilia N.; Xiao, Kai; Yoon, Mina; Geohegan, David B.

2015-01-01

The formation of semiconductor heterojunctions and their high-density integration are foundations of modern electronics and optoelectronics. To enable two-dimensional crystalline semiconductors as building blocks in next-generation electronics, developing methods to deterministically form lateral heterojunctions is crucial. Here we demonstrate an approach for the formation of lithographically patterned arrays of lateral semiconducting heterojunctions within a single two-dimensional crystal. Electron beam lithography is used to pattern MoSe2 monolayer crystals with SiO2, and the exposed locations are selectively and totally converted to MoS2 using pulsed laser vaporization of sulfur to form MoSe2/MoS2 heterojunctions in predefined patterns. The junctions and conversion process are studied by Raman and photoluminescence spectroscopy, atomically resolved scanning transmission electron microscopy and device characterization. This demonstration of lateral heterojunction arrays within a monolayer crystal is an essential step for the integration of two-dimensional semiconductor building blocks with different electronic and optoelectronic properties for high-density, ultrathin devices. PMID:26198727

MOSES Support Platform

DTIC Science & Technology

2008-02-01

drain with collector • Final pressure switch with gauge and automatic shut- off • (2) Hour meter • Oil filled finel pressure gauge 0~400bar/5800psi...Automatic condensate drain system Final pressure switch with gauge and automatic shut-off (2) Hour meter, (2) On/Off Switch Filling Connection Four

For Your Bookshelf.

ERIC Educational Resources Information Center

Jones, Rebecca

2002-01-01

Reviews notable education books of 2001: "Not in Front of the Children" (Marjorie Heins); "The other Boston Busing Story" (Susan E. Eaton); "Another Planet" (Elinor Burkett); "Parents Under Siege" (James Garbarino and Claire Bedard); "Radical Equations" (Robert P. Moses and Charles E. Cobb, Jr.); "School" (Sheila Curran Bernard and Sarah Mondale);…

STS-120 Orbit 2 Flight Control Team Photo

NASA Image and Video Library

2007-10-31

JSC2007-E-095908 (31 Oct. 2007) --- The members of the STS-120 Orbit 2 flight control team pose for a group portrait in the space shuttle flight control room of Houston's Mission Control Center (MCC). Flight director Mike Moses holds the STS-120 mission logo.

Between Teaching and Research: Challenges of the Academic Profession in Croatia

ERIC Educational Resources Information Center

Turk, Marko; Ledic, Jasminka

2016-01-01

Discussions about synergy or independence of teaching and research are present in many studies (Bilic, 2009; Brew & Boud, 1995; Enders & Teichler, 1997; Griffiths, 2004; Jakovljevic, 2010; Jenkins, 2000; Ramsden & Moses, 1992). Humboldt's model introduced synergy between teaching and research, thus highlighting the importance of…

Deformation of Water by a Magnetic Field

ERIC Educational Resources Information Center

Chen, Zijun; Dahlberg, E. Dan

2011-01-01

After the discovery that superconducting magnets could levitate diamagnetic objects, researchers became interested in measuring the repulsion of diamagnetic fluids in strong magnetic fields, which was given the name "The Moses Effect." Both for the levitation experiments and the quantitative studies on liquids, the large magnetic fields necessary…

What If Grandma Moses Attended Night School? Strategies for Reprioritizing Adult Art Education.

ERIC Educational Resources Information Center

Edelson, Paul J.

Through their own inventiveness and persistence, adults are circumventing institutional indifference and creating alternative educational networks to teach themselves art. Problems that must be overcome are as follows: inadequate instructor preparation, a generally narrow array of programs in most community centers with the preponderance of…

Exercise-Induced Changes in Metabolic Resposes to Infection in Trained Rats.

DTIC Science & Technology

1981-07-20

superimposed on fasting reduced it in sedentary rats (24). Swimming amplified fasting ketosis and diminished infection ketonemia and markedly decreased...Ketone body metabolism in the ketosis of starvation and alloxan diabetes. J. Biol. Chem. 245:4382-4390, 1970. 22. MOSES, L. E. Determination of oxygen

76 FR 81493 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-28

... scrap materials, the removal of mercury switches, and binder formulations. Large iron and steel..., or financial resources expended by persons to generate, maintain, retain, or disclose or provide... reiterated in this ICR. Dated: December 21, 2011. John Moses, Director, Collection Strategies Division. [FR...

Waves in Nature, Lasers to Tsumanis and Beyond

ScienceCinema

LLNL - University of California Television

2017-12-09

Waves are everywhere. Microwaves, laser beams, music, tsunamis. Electromagnetic waves emanating from the Big Bang fill the universe. Learn about the similarities and difference in all of these wavy phenomena with Ed Moses and Rick Sawicki, Lawrence Livermore National Laboratory scientists Series: Science on Saturday [10/2006] [Science] [Show ID: 11541

Waves in Nature, Lasers to Tsumanis and Beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

LLNL - University of California Television

2008-05-01

Waves are everywhere. Microwaves, laser beams, music, tsunamis. Electromagnetic waves emanating from the Big Bang fill the universe. Learn about the similarities and difference in all of these wavy phenomena with Ed Moses and Rick Sawicki, Lawrence Livermore National Laboratory scientists Series: Science on Saturday [10/2006] [Science] [Show ID: 11541

Gifted Sixth-Graders and Primary Source Philosophy.

ERIC Educational Resources Information Center

White, David A.; Schlaggar, Sheila

1993-01-01

A sixth-grade gifted class studied the history of philosophy, including selections from such philosophers as Plato, Confucius, Buddha, Marcus Aurelius, and Moses Maimonides. Readings drew on fundamental features of child experience, such as their sense of justice, concern for moral values, and questions about reality. The paper describes classroom…

Reconstruction Era: Resources for a Balanced Approach.

ERIC Educational Resources Information Center

Seiter, David M.

1989-01-01

Lists instructional materials from the ERIC database that focus on the Reconstruction. Includes materials that present a balanced approach to this period of U.S. history. Offers documents concerned with Black education, the Freedmen's Bureau, the Indian Territory, textbook evaluation, Black women's education, and Reverend Moses Drury Hoge. (KO)

[A comment on Max Eitingon's address at the session held by the Chewrah Psychoanalytith b'Erez-Israel in Jerusalem on May 6th, 1939].

PubMed

Eickhoff, Friedrich-Wilhelm

2006-01-01

The paper sketches the context of Eitingon's address in celebration of Freud's 83rd birthday (which follows hereafter), especially regarding the recent publication of Freud's book on Moses which Erich Gumbel presented with great care on this occasion.

Galvanic Skin Response as a Measure of Soldier Stress

DTIC Science & Technology

2007-05-01

in the body have been used as an effective measure of stress, including social stress such as performance in front of an audience (Nater, La Marca ...Lake, CA, 1992. Nater, U. M.; La Marca , R.; Florin, L.; Moses, A.; Langhans, W.; Koller, M. M.; Ehlert, U. Stress-Induced Changes in Human

MOSES - Inflatable Causeway

DTIC Science & Technology

2007-08-01

Diameter ........................................................... 13 Figure 14: Braid Angle...must be resisted, and Beta which is the bias angle of the braid . This equation is specific to a fabric that is braided and not woven. Figure 14...shows what the bias angle in a braided fabric. Figure 14: Braid Angle Because braided fabrics are stronger than woven for air beams, braided

36 CFR 7.20 - Fire Island National Seashore.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Fire Island National Seashore. 7.20 Section 7.20 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE... adjacent to Robert Moses State Park, east to the western boundary of the Sunken Forest, excluding any area...

36 CFR 7.20 - Fire Island National Seashore.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Fire Island National Seashore. 7.20 Section 7.20 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE... adjacent to Robert Moses State Park, east to the western boundary of the Sunken Forest, excluding any area...

36 CFR 7.20 - Fire Island National Seashore.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Fire Island National Seashore. 7.20 Section 7.20 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE... adjacent to Robert Moses State Park, east to the western boundary of the Sunken Forest, excluding any area...

36 CFR 7.20 - Fire Island National Seashore.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Fire Island National Seashore. 7.20 Section 7.20 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE... adjacent to Robert Moses State Park, east to the western boundary of the Sunken Forest, excluding any area...

Moses and Superman Come Home: Counseling Adoptees and Adoptive Families.

ERIC Educational Resources Information Center

Saiz, Stephen G.

This paper looks at three parties impacted by adoption: the adoptive parents, the adopted child, and the adoptive family. When working with adoptive parents, counselors should respect the strength of the couple, their commitment to parenthood, and the closeness that may develop from weathering the issue of childlessness. Adoptive parents are…

Impact of Erb-B Signaling on Myelin Repair in the CNS Following Virus-Induced Damage

DTIC Science & Technology

2008-03-01

REFERENCES 1. Yahli Lorch, Adam Freidmann, Howard L. Lipton, and Moshe Kotler : Theiler’s murine encephalomyelitis virus group includes two...21-27 (2003) 123. Cynthia Rivera-Quinones, Dorian McGavern, James D. Schmelzer, Samuel F. Hunter, Philip A. Low, and Moses Rodriguez: Absence of

76 FR 26681 - Hours of Service of Drivers

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-09

.... Jovanis, J.P., Wu, K.F., and Chen, C., ``Hours of Service and Driver Fatigue--Driver Characteristics... 2010. Sando, T., Mtoi, E., and Moses, R., ``Potential Causes Of Driver Fatigue: A Study On Transit Bus..., 390, and 395 [Docket No. FMCSA-2004-19608] RIN 2126-AB26 Hours of Service of Drivers AGENCY: Federal...

NASA Patent Abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 21) Abstracts

NASA Technical Reports Server (NTRS)

1982-01-01

Abstracts are cited for 87 patents and applications introduced into the NASA scientific and technical information system during the period of January 1982 through June 1982. Each entry consists of a citation, an abstract, and in mose cases, a key illustration selected from the patent or patent application.

Tuning the p-type Schottky barrier in 2D metal/semiconductor interface:boron-sheet on MoSe2, and WSe2

NASA Astrophysics Data System (ADS)

Couto, W. R. M.; Miwa, R. H.; Fazzio, A.

2017-10-01

Van der Waals (vdW) metal/semiconductor heterostructures have been investigated through first-principles calculations. We have considered the recently synthesized borophene (Mannix et al 2015 Science 350 1513), and the planar boron sheets (S1 and S2) (Feng et al 2016 Nat. Chem. 8 563) as the 2D metal layer, and the transition metal dichalcogenides (TMDCs) MoSe2, and WSe2 as the semiconductor monolayer. We find that the energetic stability of those 2D metal/semiconductor heterojunctions is mostly ruled by the vdW interactions; however, chemical interactions also take place in borophene/TMDC. The electronic charge transfer at the metal/semiconductor interface has been mapped, where we find a a net charge transfer from the TMDCs to the boron sheets. Further electronic structure calculations reveal that the metal/semiconductor interfaces, composed by planar boron sheets S1 and S2, present a p-type Schottky barrier which can be tuned to a p-type ohmic contact by an external electric field.

Thermionic Energy Conversion Based on Graphene van der Waals Heterostructures

PubMed Central

Liang, Shi-Jun; Liu, Bo; Hu, Wei; Zhou, Kun; Ang, L. K.

2017-01-01

Seeking for thermoelectric (TE) materials with high figure of merit (or ZT), which can directly converts low-grade wasted heat (400 to 500 K) into electricity, has been a big challenge. Inspired by the concept of multilayer thermionic devices, we propose and design a solid-state thermionic devices (as a power generator or a refrigerator) in using van der Waals (vdW) heterostructure sandwiched between two graphene electrodes, to achieve high energy conversion efficiency in the temperature range of 400 to 500 K. The vdW heterostructure is composed of suitable multiple layers of transition metal dichalcogenides (TMDs), such as MoS2, MoSe2, WS2 and WSe2. From our calculations, WSe2 and MoSe2 are identified as two ideal TMDs (using the reported experimental material’s properties), which can harvest waste heat at 400 K with efficiencies about 7% to 8%. To our best knowledge, this design is the first in combining the advantages of graphene electrodes and TMDs to function as a thermionic-based device. PMID:28387363

Thermal stability of MBE-grown epitaxial MoSe2 and WSe2 thin films

NASA Astrophysics Data System (ADS)

Chang, Young Jun; Choy, Byoung Ki; Phark, Soo-Hyon; Kim, Minu

Layered transition metal dichalcogenides (TMDs) draw much attention, because of its unique optical properties and band structures depending on the layer thicknesses. However, MBE growth of epitaxial films demands information about thermal stability of stoichiometry and related electronic structure for high temperature range. We grow epitaxial MoSe2 and WSe2 ultrathin films by using molecular beam epitaxy (MBE). We characterize stoichiometry of films grown at various growth temperature by using various methods, XPS, EDX, and TOF-MEIS. We further test high temperature stability of electronic structure for those films by utilizing in-situ ellipsometry attached to UHV chamber. We discuss threshold temperatures up to 700~1000oC, at which electronic phases changes from semiconductor to metal due to selenium deficiency. This information can be useful for potential application of TMDs for fabrication of Van der Waals multilayers and related devices. This research was supported by Nano.Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning. (2009-0082580), NRF-2014R1A1A1002868.

Direct optical transitions at K- and H-point of Brillouin zone in bulk MoS2, MoSe2, WS2, and WSe2

NASA Astrophysics Data System (ADS)

Kopaczek, J.; Polak, M. P.; Scharoch, P.; Wu, K.; Chen, B.; Tongay, S.; Kudrawiec, R.

2016-06-01

Modulated reflectance (contactless electroreflectance (CER), photoreflectance (PR), and piezoreflectance (PzR)) has been applied to study direct optical transitions in bulk MoS2, MoSe2, WS2, and WSe2. In order to interpret optical transitions observed in CER, PR, and PzR spectra, the electronic band structure for the four crystals has been calculated from the first principles within the density functional theory for various points of Brillouin zone including K and H points. It is clearly shown that the electronic band structure at H point of Brillouin zone is very symmetric and similar to the electronic band structure at K point, and therefore, direct optical transitions at H point should be expected in modulated reflectance spectra besides the direct optical transitions at the K point of Brillouin zone. This prediction is confirmed by experimental studies of the electronic band structure of MoS2, MoSe2, WS2, and WSe2 crystals by CER, PR, and PzR spectroscopy, i.e., techniques which are very sensitive to critical points of Brillouin zone. For the four crystals besides the A transition at K point, an AH transition at H point has been observed in CER, PR, and PzR spectra a few tens of meV above the A transition. The spectral difference between A and AH transition has been found to be in a very good agreement with theoretical predictions. The second transition at the H point of Brillouin zone (BH transition) overlaps spectrally with the B transition at K point because of small energy differences in the valence (conduction) band positions at H and K points. Therefore, an extra resonance which could be related to the BH transition is not resolved in modulated reflectance spectra at room temperature for the four crystals.

If You Meet Moses/Jesus/Mohammed/Buddha (or Associate Editors of Theory) on the Road, Kill Them!

ERIC Educational Resources Information Center

Ginter, Earl J.

1989-01-01

Presents reactions to Hershenson, Power, and Seligman's rejoinder in July 1989 issue of Journal of Mental Health Counseling (JMHC). Argues against relying upon either medical model or eclectic approach as a foundation for mental health counseling. Suggests Ivey's views (JMHC, January 1989) concerning developmental issues and author's views…

Deformation of Water by a Magnetic Field

NASA Astrophysics Data System (ADS)

Chen, Zijun; Dahlberg, E. Dan

2011-03-01

After the discovery that superconducting magnets could levitate diamagnetic objects,1,2 researchers became interested in measuring the repulsion of diamagnetic fluids in strong magnetic fields,3-5 which was given the name "The Moses Effect."5 Both for the levitation experiments and the quantitative studies on liquids, the large magnetic fields necessary were produced by superconducting magnets.

78 FR 16247 - Approval for Export-Only Manufacturing Authority, Foreign-Trade Zone 203, SGL Automotive Carbon...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-14

... Manufacturing Authority, Foreign-Trade Zone 203, SGL Automotive Carbon Fibers, LLC, (Carbon Fiber Manufacturing... SGL Automotive Carbon Fibers, LLC, within FTZ 203-Site 3, in Moses Lake, Washington (FTZ Docket 4-2011... Carbon Fibers, LLC, as described in the application and Federal Register notice, is approved, subject to...

The Development of an ICF-Oriented, Adaptive Physician Assessment Instrument of Mobility, Self-care, and Domestic Life

ERIC Educational Resources Information Center

Farin, Erik; Fleitz, Annette

2009-01-01

The objective of this study was development and psychometric testing of an adaptive, International Classification of Functioning, Disability, and Health (ICF)-oriented questionnaire to be processed by the rehabilitation physician that aids in assessing mobility, self-care, and domestic life (Moses-Physician). The intent is to develop a physician…

CTC Sentinel. Volume 6, Issue 8, August 2013

DTIC Science & Technology

2013-08-01

Iran. Hizb Allah to Iran isn’t a card to play with. Hizb Allah today is the crown jewel of the resistance bloc; presidential moderation doesn’t mean...video recorded on a Hizb Allah fighter’s phone of the IRAM in action. 48 “ DIY Weapons in Syria – Hezbollah Deploys IRAMs in Qusayr,” Brown Moses

Democracy under Fire: Voter Confusion and Influences in Colorado's Anti-Affirmative Action Initiative

ERIC Educational Resources Information Center

Farley, Amy N.; Gaertner, Matthew N.; Moses, Michele S.

2013-01-01

In this article, Amy N. Farley, Matthew N. Gaertner, and Michele S. Moses examine the use of ballot initiatives as a particularly attractive form of direct democracy for opponents of affirmative action in higher education. Building on previous scholarship, the authors question whether anti-affirmative ballot initiatives validly reflect voters'…

Cost Functions for Airframe Production Programs.

DTIC Science & Technology

1982-07-01

0 : 666QOOO 66u666=6L66 𔃺" ~ JM. ~ ~ OJ M %~ 0v Z𔃾:O 14% tqv6 Z6 6 𔃺 *1 199 REFERENCES 1. Alchian, Armen A. "Costs and Outputs." In, The...Allocation of Economic Resources, Edited by Moses Abramovitz. Stanford, California: Stanford University Press, 1959. 2. Alchian, Armen A. "Reliability of

A Model for Teaching Midrash in the Primary School: Forming Understandings of Rabbinic Interpretation of Scripture

ERIC Educational Resources Information Center

Sigel, Deena

2010-01-01

In Jewish primary schools, religious education is centred on the study of Torah. At Sinai, according to Jewish tradition, Moses received the Torah in two parts: a written tradition (Hebrew scripture) and an oral tradition. The oral tradition contained much scriptural "interpretation" known, in Hebrew, as midrash. Midrash continued to be…

78 FR 40260 - International Joint Commission: Public Comment on a Proposal for Lake Ontario and St. Lawrence...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

... DEPARTMENT OF STATE [Public Notice 8369] International Joint Commission: Public Comment on a... inviting the public to comment on a proposal for managing the water levels and flows in Lake Ontario and.... Lawrence River. Since 1960, the IJC has managed the flow of water at the Moses- Saunders hydropower dam...

Suitability of Shale Fuels for Army Generator Sets.

DTIC Science & Technology

1981-12-01

J.N., Owens, E.C., Naegeli , D.W., and Stavinoha, L.L., "Mili- tary Fuels Refined From Paraho-II Shale Oil," Interim Report AFLRL No. 131, March 1981...Temperature Jet Fuel", NAPTC-PE-112, Naval Air Propulsion Center, Trenton, NJ, August 1977. 40. Moses, C. A. and Naegeli , D. W., "Fuel Property Effects

National Ignition Facility Construction Safety Management Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warner, B.E.

2000-02-01

An accident occurred at the NIF construction site on January 13, 2000, in which a worker sustained a serious injury when a 42-inch-diameter duct fell during installation. Following the accident, NIF Project Management chartered two review teams: (1) an Incident Analysis Team to independently assess the direct and root causes of the accident, and (2) a Management Review Team to review the roles and responsibilities of the line, support, and construction management organizations involved. This report provides a discussion of the information gathered by the Management Review Team and provides a list of observations and recommendations based on an analysismore » of the information. The Management Review Team includes senior managers who represent several Directorates within LLNL and DOE OAK: Dick Billia representing Engineering; Dave Leary representing Business Services and Public Affairs; Jim Jackson representing Hazards Control; Chuck Taylor representing DOE OAK; Arnie Clobes representing the ICF/NIF Program; and Jon Yatabe and Bruce Warner (Chairperson) representing the NIF Project. The attached letter from the NIF Project Manager, Ed Moses, to the Management Review Team contains the team's Charter. The team was asked to evaluate the effectiveness of the line management and its supporting safety functions in managing safety during NIF construction. The evaluation was to include the current conventional facility construction, which is 85% complete, and upcoming activities such as Beampath Infrastructure System installation, which will begin in the next six months and which represents a significant amount of work over the next two to three years. The remainder of this document describes the Management Review Team's review process (Section 2), its observations gathered during the review (Section 3), and its recommendations to the NIF Project Manager based on those observations (Section 4).« less

The Idea of the Visiting Inquiry in Comparative Education: The 1903 Mosely Commission and the United States

ERIC Educational Resources Information Center

Lawn, Martin

2015-01-01

Through a study of a privately funded and ambitious inquiry into the education system of the United States, the relations between the development of comparative education as an activity and the governing of education systems in the early 20th century can be illuminated. The relations and interests of early comparativists were mobilized and…

STUDIES ON THE METABOLISM OF 6-NITROCHRYSENE AND THE FORMATION OF DNA ADDUCTS IN THE LIVER, LUNG AND BLADDER OF A/J MICE

EPA Science Inventory

/
Studies On The Metabolism of 6-Nitrochrysene and The Formation of DNA Adducts in the Liver, Lung and Bladder ofAJJ Mice
Moses McDaniel*, Linda Adamst, Joycelyn Allisont, Michael George"l", Dhimant Desai+, 5hantu Amin+, Guy Lambertt, William Padgettt, Stephen Nesnowt and...

O 'Iluminismo' na Alemanha--As Concepcoes de Mendelssohn e Kant (The 'Enlightenment' in Germany--The Concepts of Mendelssohn and Kant).

ERIC Educational Resources Information Center

Mainka, Peter Johann

2000-01-01

States that in 1783 J. F. Zollner, a Berlin theologian, asked the question: "What is 'Enlightenment'?" Notes that the next year Immanuel Kant and Moses Mendelssohn gave definitions of the Enlightenment that are famous in the history of ideas. Analyzes and discusses the definitions through keywords such as reason, criticism, and…

Design, the "Straw" Missing from the "Bricks" of IS Curricula

ERIC Educational Resources Information Center

Waguespack, Leslie J.

2011-01-01

As punishment in the biblical story of Moses the slaves were told they had to make bricks without straw. This was impossible because bricks made without straw had the appearance of strength and function but could not withstand the proof of actual use. The slaves' punishment was therefore not only to make bricks, but also to find the straw on their…

78 FR 56655 - Foreign-Trade Zone (FTZ) 203-Moses Lake, Washington; Notification of Proposed Production Activity...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-13

... choose the duty rate during customs entry procedures that applies to fuel rod assemblies (duty rate--3.3... plates; channels; spacers; end caps; springs; top and bottom nozzles; cages; guide tubes; and tubes, bar stocks, wires and plates of zirconium (duty rate ranges from 3.3 to 3.7%). Public comment is invited from...

The past, present, and future of soils and human health studies

USDA-ARS?s Scientific Manuscript database

The idea that human health is tied to the soil is not a new one. As far back as circa 1400 B.C. the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. In 400 B.C. the Greek philosopher Hippocrates provided a list of things that should be considered ...

Effects of High Availability Fuels on Combustor Properties

DTIC Science & Technology

1978-01-01

EFFECT OF HIGH AVAILABILITY FUELS ON COMBUSTOR PROPERTIES INTERIM REPORT AFLRL No. 101 by C. A. Moses and D. W. Naegeli prepared by U. S. Army Fuels...C-,0•)a3 D.W. / Naege I i_• //• DAAK 7/,0’ 7 8 - C -,9ak1 9 PERFORMING ORGANIZATION NAME AND ADDRESSES - ,_ _ECT, TASK U.S. Army Fuels & Lubricants

Fuel Property Effects on Combustor Performance.

DTIC Science & Technology

1980-03-01

emissions measurements are given in a previous report by Moses and Nae- geli . (4) 8 B. Combustor Rigs A Phillips-designed, 2-inch-diameter, high...333 311 80 256 262 270 294 331 176 342 321 85 261 268 277 308 340 188 352 333 90 267 275 295 324 351 200 364 346 95 274 297 322 347 367 215 382 364

Groundworks for a Pedagogy of Evolutionary Love Ethics: Archetypes of Moral Imagination in the Pragmatisms of Peirce and Addams

ERIC Educational Resources Information Center

Moses, Russell G.

2017-01-01

In this essay, Russell G. Moses argues that Charles Sanders Peirce's article "Evolutionary Love" establishes a general normative framework for a logic of evolutionary, progressive imagination that can be used to elucidate an evolutionary continuity between the normative works of Jane Addams, John Dewey, and Alain Locke. This exercise…

Megafloods and Clovis cache at Wenatchee, Washington

NASA Astrophysics Data System (ADS)

Waitt, Richard B.

2016-05-01

Immense late Wisconsin floods from glacial Lake Missoula drowned the Wenatchee reach of Washington's Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP, raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As advancing ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia past Wenatchee. Ice then blocked Moses Coulee, and Grand Coulee to Quincy basin became the westmost floodway. From Quincy basin many Missoula floods backflowed 50 km upvalley to Wenatchee 18,000 to 15,500 years ago. Receding ice dammed glacial Lake Columbia centuries more-till it burst about 15,000 years ago. After Glacier Peak ashfall about 13,600 years ago, smaller great flood(s) swept down the Columbia from glacial Lake Kootenay in British Columbia. The East Wenatchee cache of huge fluted Clovis points had been laid atop Pangborn bar after the Glacier Peak ashfall, then buried by loess. Clovis people came five and a half millennia after the early gigantic Missoula floods, two and a half millennia after the last small Missoula flood, and two millennia after the glacial Lake Columbia flood. People likely saw outburst flood(s) from glacial Lake Kootenay.

Excitation energy dependent Raman spectrum of MoSe2

PubMed Central

Nam, Dahyun; Lee, Jae-Ung; Cheong, Hyeonsik

2015-01-01

Raman investigation of MoSe2 was carried out with eight different excitation energies. Seven peaks, including E1g, A1g, E2g1, and A2u2 peaks are observed in the range of 100–400 cm−1. The phonon modes are assigned by comparing the peak positions with theoretical calculations. The intensities of the peaks are enhanced at different excitation energies through resonance with different optical transitions. The A1g mode is enhanced at 1.58 and 3.82 eV, which are near the A exciton energy and the band-to-band transition between higher energy bands, respectively. The E2g1 mode is strongly enhanced with respect to the A1g mode for the 2.71- and 2.81-eV excitations, which are close to the C exciton energy. The different enhancements of the A1g and E2g1 modes are explained in terms of the symmetries of the exciton states and the exciton-phonon coupling. Other smaller peaks including E1g and A2u2 are forbidden but appear due to the resonance effect near optical transition energies. PMID:26601614

Single-Nanoflake Photo-Electrochemistry Reveals Champion and Spectator Flakes in Exfoliated MoSe 2 Films

DOE PAGES

Todt, Michael A.; Isenberg, Allan E.; Nanayakkara, Sanjini U.; ...

2018-03-06

Semiconducting transition-metal dichalcogenide (TMD) nanoflake thin films are promising large-area electrodes for photo-electrochemical solar energy conversion applications. However, their energy conversion efficiencies are typically much lower than those of bulk electrodes. It is unclear to what extent this efficiency gap stems from differences among nanoflakes (e.g., area, thickness, and surface structural features). It is also unclear whether individual exfoliated nanoflakes can achieve energy conversion efficiencies similar to those of bulk crystals. Here, we use a single-nanoflake photo-electrochemical approach to show that there are both highly active and completely inactive nanoflakes within a film. For the exfoliated MoSe 2 samples studiedmore » herein, 7% of nanoflakes are highly active champions, whose photocurrent efficiency exceeds that of the bulk crystal. However, 66% of nanoflakes are inactive spectators, which are mostly responsible for the overall lower photocurrent efficiency compared to the bulk crystal. The photocurrent collection efficiency increases with nanoflake area and decreases more at perimeter edges than at interior step edges. These observations, which are hidden in ensemble-level measurements, reveal the underlying performance issues of exfoliated TMD electrodes for photo-electrochemical energy conversion applications.« less

Climatic Controls on Forest Productivity in Western North America; Variability, Covariability, and Projected Change

NASA Astrophysics Data System (ADS)

Hawkins, L. R.; Rupp, D. E.; Li, S.; Mote, P.; Sparrow, S.; Massey, N.

2016-12-01

The forests of western North America serve as a carbon sink sequestering carbon and slowing the rise of CO2 in the atmosphere. Though still positive, the rate of net carbon uptake has been in decline over the past two decades. Regional drought has been shown to slow forest productivity and net carbon uptake despite warmer temperatures and longer growing seasons. With drought conditions projected to increase in frequency and severity under climate change there is concern that these forests' capacity as an effective carbon sink will continue to decrease in the future. To investigate how changes in regional hydroclimate may affect future carbon uptake in western US forests we dynamically downscaled global climate simulations using a 25-km resolution regional climate model HadRM3P with the land surface scheme MOSES2. We generated a 100-member ensemble of simulations for an historical period (1985-2015) and mid-21st century period (2030-2060) under Representative Concentration Pathway 8.5. We evaluated the effects of regional changes in atmospheric moisture demand, seasonality of water supply, and water stress on forest productivity and carbon uptake. We investigated how these changes in hydroclimate interact with the relaxing of temperature controls. This work can inform future adaptation efforts through improving our understanding of climatic controls on forest carbon sequestration.

Keeping on: How ALP Brings Disaffected Youth Back to School in Liberia

ERIC Educational Resources Information Center

von Hahmann, Gail; Tengbeh, Josephine F. D.

2008-01-01

Moses is entering 7th grade this semester. He is a graduate of the Accelerated Learning Program (ALP), a Liberian government initiative to assist over-age students to complete six grades of primary school in three years. He has all the interests of a typical 15-year old--fixing generators, playing football, earning money to buy a school uniform.…

Monitor for Sterilization Procedures

DTIC Science & Technology

2001-10-25

were tested using ampules of Bacillus stearothermophilus spores commercially manufactured by Barnstead/Thermolyne for testing sterilization procedures...Monitor for Sterilization Procedures F. Cleary1,2, H.-Y. Mason2, C. Estes2, A. Duncan2, W. Ellis, Jr.2 and L. Powers2 1Moses Brown High School...accurate determination of the efficacy of sterilization procedures is demonstrated using a hand-held instrument based on the intrinsic fluorescence of

76 FR 19989 - New York State Prohibition of Discharges of Vessel Sewage; Receipt of Petition and Tentative...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-11

... readily available for pumpout while the ferries are docked in Bridgeport. SUNY Maritime College's large...: Notice is hereby given that, pursuant to Clean Water Act, Section 312(f)(3) (33 U.S.C. 1322(f)(3)), the... and Hand Delivery/Courier: Moses Chang, U.S. EPA Region 2, 290 Broadway, 24th Floor, New York, NY...

Women in History--Madame C. J. Walker 1867-1919

ERIC Educational Resources Information Center

Huber, Germaine W.

2009-01-01

This article profiles Madame C. J. Walker. Sarah Breedlove was born on December 23, 1867, the fifth of six children of Owen and Minerva Breedlove. Sarah was the first of the Breedlove children to be born after the end of slavery. Her parents died when she was six or seven years of age. At age fourteen she married Moses McWilliams, who also died in…

PIALA '97. Wasahn Kamarain: Place of Enlightenment. Papers from the Pacific Islands Association of Libraries and Archives Conference (7th, Palikir, Pohnpei, November 3-5, 1997).

ERIC Educational Resources Information Center

Cohen, Arlene, Ed.

This PIALA 1997 Proceedings follows the tradition of publishing papers from each annual conference of the Pacific Islands Association of Libraries and Archives (PIALA). After welcoming remarks from Sue Moses, Kapily Capelle, and Isabel Rungrad, the following papers are included: "Places of Enlightenment, Places of Dreams" (Maradel Gale);…

[Maimonides, a physician in the 12 century. Contribution to the history of medical ethics and deontology].

PubMed

Pavlović, B

2000-01-01

Maimonides, Moses ben Maimon (1135-1204), Jewish physician, philosopher and scholar was the first after Hippocrates to write a text of a "prayer" he spoke out at the beginning of his medical profession, e. i. when he took oath. The text of "Maimonides's prayer" is today obligatory in some schools of medicine in the United States of America.

A brief history of soils and human health work and needs for the future

USDA-ARS?s Scientific Manuscript database

The idea that human health is tied to the soil is not a new one. As far back as circa 1400 B.C. the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. In 400 B.C. the Greek philosopher Hippocrates provided a list of things that should be considered ...

European Scientific Notes. Volume 34, Number 10,

DTIC Science & Technology

1980-10-31

vivo use because of its short half- According to Pfannenstiel there are life, its favorable photon emissions more than 50 different forms of known thy...of medical professionals from 3 ity, biological half-lives, dosimetry countries. (Moses A. Greenfield) (absorbed dose), and the differential di...for the Advancement The crash was a serious blow for of Siene wre tld hatther isa mjor European scientists including Britain’s ga tatisrapidly

Un-Building Blocks: A Model of Reverse Engineering and Applicable Heuristics

DTIC Science & Technology

2015-12-01

CONCLUSIONS The machine does not isolate man from the great problems of nature but plunges him more deeply into them. Antoine de Saint-Exupery— Wind ...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Reverse engineering is the problem -solving activity that ensues when one takes a...Douglas Moses, Vice Provost for Academic Affairs iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT Reverse engineering is the problem -solving

Glasgow Coma Scores, Early Opioids, and Posttraumatic Stress Disorder Among Combat Amputees

DTIC Science & Technology

2014-04-01

icz, Johnson, & Mosely, 2008). Little research has compared how morphine and fentanyl might impact later psychological outcomes such as PTSD. In the...Fox, Saunders, Menk, & Middaugh, 1995). Because the analgesic effect of fentanyl is approximately 100 times more than morphine , the median Level 2...dosages administered to patients for these opioids appeared equivalent for analgesic effectiveness (Fox et al., 1995). Of the morphine -treated pa

Purification and Pore Forming Activity of Two Hydrophobic Polypeptides from the Secretion of the Red Sea Moses Sole (Pardachirus marmoratus)

DTIC Science & Technology

1986-11-01

Uppsala, Sweden. Ovalbumin, bovine albumin fractio n V, soybean lecithin , sodium cnolate, gramicidin D and Dowex 50 x 8 (50-100 mesh) were obtained from...A-,.ino acid analysis 50 ug duplIcate samples of PXI and PXII, from reverse phase HPLC, were dissolved in 0.4 ml of 6 N HCI and hydrolyzed ocr 24 hr

List of ARI Conference Papers, Journal Articles, Books, and Book Chapters: 1982-1991

DTIC Science & Technology

1992-10-01

and Engineering Applications of Artificial Intelligence and Expert Systems, Tullahoma, TN. Goehring, D.J., & Hart, R.J. (1985, October). Automated...systems: Computkr-based authoring. Proceedings of the 30th annual meeting of the Artificial Intelligence Society, Dayton, OH. Knapp, D.J., & Pliske, R.M...Moses, F.L. (1984-85) Intelligence vehicle integrated displays. Paper presented at the Conference on Applied Artificial Intelligence , the Data Processing

Mechanisms of Smoke Reduction in the High Pressure Combustion of Emulsified Fuels. Volumn I. Construction of Apparatus and Preliminary Experiments.

DTIC Science & Technology

1981-10-01

Naegeli and Thomas Ryan have made a number of helpful suggestions. Ms. D. Miller, Ms. E. Gonzales, and Mr. J. Pryor are thanked for helping prepare this...October 1976. 2. Naegeli , D.W., Fodor, G.E., and Moses, C.A., "Fuel Microemulsions for Jet Engine Smoke Reduction," to be presented at the ASME Gas

A TRANSITION REGION EXPLOSIVE EVENT OBSERVED IN He II WITH THE MOSES SOUNDING ROCKET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, J. Lewis; Kankelborg, Charles C.; Thomas, Roger J., E-mail: fox@physics.montana.ed, E-mail: kankel@solar.physics.montana.ed, E-mail: Roger.J.Thomas@nasa.go

2010-08-20

Transition region explosive events (EEs) have been observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548 A, 1550 A) and Si IV (1393 A, 1402 A). We report what we believe to be the first observation of a transition region EE in He II 304 A. With the Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket, a novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel. The jets have sky-planemore » velocities of order 75 km s{sup -1} and line-of-sight velocities of +75 km s{sup -1} (blue) and -30 km s{sup -1} (red). The core is a region of high non-thermal Doppler broadening, characteristic of EEs, with maximal broadening 380 km s{sup -1} FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum Doppler velocities +160 km s{sup -1} and -220 km s{sup -1}. The event lasts more than 150 s. Its properties correspond to the larger, long-lived, and more energetic EEs observed in other wavelengths.« less

Tailoring Vacancies Far Beyond Intrinsic Levels Changes the Carrier Type and Optical Response in Monolayer MoSe 2-x Crystals

DOE PAGES

Mahjouri-Samani, Masoud; Liang, Liangbo; Oyedele, Akinola; ...

2016-01-01

Defect engineering has been a critical step in controlling the transport characteristics of electronic devices, and the ability to create, tune, and annihilate defects is essential to enable the range of next-generation devices. Whereas defect formation has been well-demonstrated in three-dimensional semiconductors, similar exploration of the heterogeneity in atomically thin two-dimensional semiconductors and the link between their atomic structures, defects, and properties has not yet been extensively studied. In this paper, we demonstrate the growth of MoSe 2–x single crystals with selenium (Se) vacancies far beyond intrinsic levels, up to ~20%, that exhibit a remarkable transition in electrical transport propertiesmore » from n- to p-type character with increasing Se vacancy concentration. A new defect-activated phonon band at ~250 cm -1 appears, and the A 1g Raman characteristic mode at 240 cm -1 softens toward ~230 cm -1 which serves as a fingerprint of vacancy concentration in the crystals. We show that post-selenization using pulsed laser evaporated Se atoms can repair Se-vacant sites to nearly recover the properties of the pristine crystals. Finally, first-principles calculations reveal the underlying mechanisms for the corresponding vacancy-induced electrical and optical transitions.« less

Twisted MoSe 2 bilayers with variable local stacking and interlayer coupling revealed by low-frequency Raman spectroscopy

DOE PAGES

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan; ...

2016-01-14

Unique twisted bilayers of MoSe 2 with multiple stacking orientations and interlayer couplings in the narrow range of twist angles, 60 ± 3°, are revealed by low-frequency Raman spectroscopy and theoretical analysis. The slight deviation from 60 allows the concomitant presence of patches featuring all three high-symmetry stacking configurations (2H or AA', AB', A'B) in one unique bilayer system. In this case, the periodic arrangement of the patches and their size strongly depend on the twist angle. Ab initio modeling predicts significant changes in frequencies and intensities of low-frequency modes versus stacking and twist angle. Experimentally, the variable stacking andmore » coupling across the interface is revealed by the appearance of two breathing modes corresponding to the mixture of the high-symmetry stacking configurations and unaligned regions of monolayers. Only one breathing mode is observed outside the narrow range of twist angles. This indicates a stacking transition to unaligned monolayers with mismatched atom registry without the in-plane restoring force required to generate a shear mode. As a result, the variable interlayer coupling and spacing in transition metal dichalcogenide bilayers revealed in this study may provide a new platform for optoelectronic applications of these materials.« less

Twisted MoSe 2 bilayers with variable local stacking and interlayer coupling revealed by low-frequency Raman spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan

Unique twisted bilayers of MoSe 2 with multiple stacking orientations and interlayer couplings in the narrow range of twist angles, 60 ± 3°, are revealed by low-frequency Raman spectroscopy and theoretical analysis. The slight deviation from 60 allows the concomitant presence of patches featuring all three high-symmetry stacking configurations (2H or AA', AB', A'B) in one unique bilayer system. In this case, the periodic arrangement of the patches and their size strongly depend on the twist angle. Ab initio modeling predicts significant changes in frequencies and intensities of low-frequency modes versus stacking and twist angle. Experimentally, the variable stacking andmore » coupling across the interface is revealed by the appearance of two breathing modes corresponding to the mixture of the high-symmetry stacking configurations and unaligned regions of monolayers. Only one breathing mode is observed outside the narrow range of twist angles. This indicates a stacking transition to unaligned monolayers with mismatched atom registry without the in-plane restoring force required to generate a shear mode. As a result, the variable interlayer coupling and spacing in transition metal dichalcogenide bilayers revealed in this study may provide a new platform for optoelectronic applications of these materials.« less

Phonon-coupled ultrafast interlayer charge oscillation at van der Waals heterostructure interfaces

NASA Astrophysics Data System (ADS)

Zheng, Qijing; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V.; Saidi, Wissam A.; Zhao, Jin

2018-05-01

Van der Waals (vdW) heterostructures of transition-metal dichalcogenide (TMD) semiconductors are central not only for fundamental science, but also for electro- and optical-device technologies where the interfacial charge transfer is a key factor. Ultrafast interfacial charge dynamics has been intensively studied, however, the atomic scale insights into the effects of the electron-phonon (e-p) coupling are still lacking. In this paper, using time dependent ab initio nonadiabatic molecular dynamics, we study the ultrafast interfacial charge transfer dynamics of two different TMD heterostructures MoS2/WS2 and MoSe2/WSe2 , which have similar band structures but different phonon frequencies. We found that MoSe2/WSe2 has softer phonon modes compared to MoS2/WS2 , and thus phonon-coupled charge oscillation can be excited with sufficient phonon excitations at room temperature. In contrast, for MoS2/WS2 , phonon-coupled interlayer charge oscillations are not easily excitable. Our study provides an atomic level understanding on how the phonon excitation and e-p coupling affect the interlayer charge transfer dynamics, which is valuable for both the fundamental understanding of ultrafast dynamics at vdW hetero-interfaces and the design of novel quasi-two-dimensional devices for optoelectronic and photovoltaic applications.

Megafloods and Clovis cache at Wenatchee, Washington

USGS Publications Warehouse

Waitt, Richard B.

2016-01-01

Immense late Wisconsin floods from glacial Lake Missoula drowned the Wenatchee reach of Washington's Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP, raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As advancing ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia past Wenatchee. Ice then blocked Moses Coulee, and Grand Coulee to Quincy basin became the westmost floodway. From Quincy basin many Missoula floods backflowed 50 km upvalley to Wenatchee 18,000 to 15,500 years ago. Receding ice dammed glacial Lake Columbia centuries more—till it burst about 15,000 years ago. After Glacier Peak ashfall about 13,600 years ago, smaller great flood(s) swept down the Columbia from glacial Lake Kootenay in British Columbia. The East Wenatchee cache of huge fluted Clovis points had been laid atop Pangborn bar after the Glacier Peak ashfall, then buried by loess. Clovis people came five and a half millennia after the early gigantic Missoula floods, two and a half millennia after the last small Missoula flood, and two millennia after the glacial Lake Columbia flood. People likely saw outburst flood(s) from glacial Lake Kootenay.

Molecular Beam Epitaxy of Layered Material Superlattices and Heterostructures

NASA Astrophysics Data System (ADS)

Vishwanath, Suresh; Liu, Xinyu; Rouvimov, Sergei; Furdyna, Jacek K.; Jena, Debdeep; Xing, Huili Grace

2014-03-01

Stacking of various layered materials is being pursued widely to realize various devices and observe novel physics. Mostly, these have been limited to exfoliation and stacking either manually or in solution, where control on rotational alignment or order of stacking is lost. We have demonstrated molecular beam epitaxy (MBE) growth of Bi2Se3/MoSe2 superlatticeand Bi2Se3/MoSe2/SnSe2 heterostructure on sapphire. We have achieved a better control on the order of stacking and number of layers as compared to the solution technique. We have characterized these structures using RHEED, Raman spectroscopy, XPS, AFM, X-ray reflectometry, cross-section (cs) and in-plane (ip) TEM. The rotational alignment is dictated by thermodynamics and is understood using ip-TEM diffraction patterns. Layered growth and long range order is evident from the streaky RHEED pattern. Abrupt change in RHEED pattern, clear demarcation of boundary between layers seen using cs-TEM and observation of Raman peaks corresponding to all the layers suggest van-der-waals epitaxy. In our knowledge this is a first demonstration of as grown superlattices and heterostuctures involving transition metal dichalcogenides and is an important step towards the goal of stacking of 2D crystals like lego blocks.

Freud's prehistoric matrix--owing 'nature' a death.

PubMed

Raphael-Leff, Joan

2007-12-01

This paper is informed by contemporary literature in two fields--neonatal research, on the one hand, and the burgeoning interdisciplinary interest in Moses and monotheism, on the other. The author postulates that a cluster of traumatic events during the first two years of Freud's life compelled him to repeat what could not be remembered. Embedded in charged implicit schema, these affects remained unprocessed in Freud, who alone of all psychoanalysts did not have an analysis, manifesting in an uncanny dread/allure of the 'prehistoric' as a dark and dangerous era relating to the archaic feminine/maternal matrix and fratricidal murderousness. Furthermore, she cites evidence to suggest that for Freud this unconsciously excluded subtext of the preoedipal era became associated with ancient Egyptian and Minoan-Mycenaean cultures, a passionate fascination actualized in his collection of antiquities yet incongruously absent in his theoretical work, with three exceptions--Egyptian allusions in Leonardo's unconscious attachment to his archaic mother; the 'Minoan-Mycenaean' analogy on discovering the pre-oedipal mother shortly after the death of Freud's own mother; and Egypt as cradle of humanity in his uncharacteristically rambling, troubled text of Moses and monotheism. The author sees Freud's conceptual avoidance yet compulsive reworking of the prehistoric matrix as a symptomatic attempt to expose early unformulated representations that 'return to exert a powerful effect'.

The effect of working memory load on semantic illusions: what the phonological loop and central executive have to contribute.

PubMed

Büttner, Anke Caroline

2012-01-01

When asked how many animals of each kind Moses took on the Ark, most people respond with "two" despite the substituted name (Moses for Noah) in the question. Possible explanations for semantic illusions appear to be related to processing limitations such as those of working memory. Indeed, individual working memory capacity has an impact upon how sentences containing substitutions are processed. This experiment examined further the role of working memory in the occurrence of semantic illusions using a dual-task working memory load approach. Participants verified statements while engaging in either articulatory suppression or random number generation. Secondary task type had a significant effect on semantic illusion rate, but only when comparing the control condition to the two dual-task conditions. Furthermore, secondary task performance in the random number generation condition declined, suggesting a tradeoff between tasks. Response time analyses also showed a different pattern of processing across the conditions. The findings suggest that the phonological loop plays a role in representing semantic illusion sentences coherently and in monitoring for details, while the role of the central executive is to assist gist-processing of sentences. This usually efficient strategy leads to error in the case of semantic illusions.

A Study of Bird Ingestions Into Large High Bypass Ratio Turbine Aircraft Engines.

DTIC Science & Technology

1984-09-01

Amrican Sparrovhawk (Kestral) 4 -- 2 5K26 Falco cherrug - Saker Falcon 36 (26-46) 1 5K54 GALLIFORNES - CHICKEN -LIKE BIRDS PHASIANIOAE - QUAILS, PHEASANTS...Palmas, Canary Is. LUX Luxembourg, Luxembourg LYS Lyon, France NAA Madras, India MAD Madrid, Spain MEL Melbourne, Australia MEX Mexico City, Mexico ...Minnesota, USA MSY New Orleans, Louisiana, USA MTY Monterrey, Mexico MYO Montevideo, Uruguay MWH Moses Lake, Washington, USA MXP Milan, Italy - Malpensa

Environmental Assessment: Resistance Training Facility Air Force Survival School Fairchild Air Force Base, Washington

DTIC Science & Technology

2007-01-01

from the Spokane area southwestward to Moses Lake and as far south as the Columbia River . Soils in the channeled scablands can be quite variable...western bluebird, red-necked grebe, great blue heron, turkey vulture, Caspian tern , black tern , and osprey. The white-tailed jackrabbit, a state...frequency are the Spokane Raceway along Hayford Road and firing range activities on FAFB and along the Spokane River . Residential development is

Design of a Generator for Near-Tangential Transonic Swirling Outflow.

DTIC Science & Technology

1984-12-01

of Turbine Blading , North American Aviation Inc, 1958. 8. Moses, H. L., Turbomachinery. Supplementary Notes, Naval Postgraduate School, 1983. 9...Streeter, V. L., and Wylie, B. E., Fluid Mqechanics, McGraw Hill, 1979 10. Vincent, E. T.,* The Theroy and Design of Gas Turbines and Jet Engines , McGraw...Radial Outflow Vanes ) Trarsonic Swirl Generation, Wedge-Arc Blading , 20. ABSTRACT (Continue on reverse side If necesary and Identify by block number

Field and Laboratory Studies for Increasing the Intrinsic Reward Value in Navy Jobs and Careers.

DTIC Science & Technology

1975-08-31

Cabe, P.A. The relation be- tween embedded figures test performance and simulator behavior. Journal of Applied Psychology , 1969, 5_3, 253-254. Blood... Psychology , 1973, 99, 137-139. Moses, J.L. Selecting vigilant types: Predicting vigilance per- formance by means of a field dependence test ...Laboratory Studies for Increasing the Intrinsic Reward Value in Navy Jobs and Careers Gerald V. Barrett Faye H. Dambrot Department of Psychology

Higher Education. Students Have Increased Borrowing and Working To Help Pay Higher Tuitions. Report to the Honorable Carol Mosely-Braun, U.S. Senate.

ERIC Educational Resources Information Center

General Accounting Office, Washington, DC. Health, Education, and Human Services Div.

This report analyzes data from the National Postsecondary Student Aid Study for 1992-93 and 1995-96. The study found that students have turned increasingly to borrowing to cope with rising education costs. The percentage of postsecondary students who borrowed to complete a bachelor's or lower degree increased from 41 percent in 1992-93 to 52…

Proceedings of the Annual Meeting of the Council of Graduate Schools in the United States (14th, Phoenix, Arizona, December 4-6, 1974).

ERIC Educational Resources Information Center

Ryan, John W., Ed.

The report of the 14th annual meeting of the Council of Graduate Schools presents a seminar on the Graduate Record Examination (GRE) Board by Lorene I. Rogers, Lincoln E. Moses, Warren W. Willingham, and Herman A. Witkin. The task force on Biomedical Sciences report is presented by Jerold Roschwalb, Lyle V. Jones, Robert H. Grant, and Penny D.…

Nursing Management Visionary Leader 2006: North Carolina chief nurse officer earns journal's annual leadership award.

PubMed

Wessman, Joan

2007-01-01

The following manuscript is the winning Visionary Leader 2006 entry submitted to Nursing Management by the staff of Moses Cone Health System, Greensboro, N.C., in recognition of Joan Wessman, chief nurse officer at the organization. Joan was formally recognized for her achievements during the opening ceremony of Congress 2006, October 15, in Philadelphia, Pa., during which she received the award, sponsored this year by B.E. Smith.

Dysregulation of mitotic machinery genes precedes genome instability during spontaneous pre-malignant transformation of mouse ovarian surface epithelial cells.

PubMed

Urzúa, Ulises; Ampuero, Sandra; Roby, Katherine F; Owens, Garrison A; Munroe, David J

2016-10-25

Based in epidemiological evidence, repetitive ovulation has been proposed to play a role in the origin of ovarian cancer by inducing an aberrant wound rupture-repair process of the ovarian surface epithelium (OSE). Accordingly, long term cultures of isolated OSE cells undergo in vitro spontaneous transformation thus developing tumorigenic capacity upon extensive subcultivation. In this work, C57BL/6 mouse OSE (MOSE) cells were cultured up to passage 28 and their RNA and DNA copy number profiles obtained at passages 2, 5, 7, 10, 14, 18, 23, 25 and 28 by means of DNA microarrays. Gene ontology, pathway and network analyses were focused in passages earlier than 20, which is a hallmark of malignancy in this model. At passage 14, 101 genes were up-regulated in absence of significant DNA copy number changes. Among these, the top-3 enriched functions (>30 fold, adj p < 0.05) comprised 7 genes coding for centralspindlin, chromosome passenger and minichromosome maintenance protein complexes. The genes Ccnb1 (Cyclin B1), Birc5 (Survivin), Nusap1 and Kif23 were the most recurrent in over a dozen GO terms related to the mitotic process. On the other hand, Pten plus the large non-coding RNAs Malat1 and Neat1 were among the 80 down-regulated genes with mRNA processing, nuclear bodies, ER-stress response and tumor suppression as relevant terms. Interestingly, the earliest discrete segmental aneuploidies arose by passage 18 in chromosomes 7, 10, 11, 13, 15, 17 and 19. By passage 23, when MOSE cells express the malignant phenotype, the dysregulated gene expression repertoire expanded, DNA imbalances enlarged in size and covered additional loci. Prior to early aneuploidies, overexpression of genes coding for the mitotic apparatus in passage-14 pre-malignant MOSE cells indicate an increased proliferation rate suggestive of replicative stress. Concomitant down-regulation of nuclear bodies and RNA processing related genes suggests altered control of nuclear RNA maturation, features recently linked to impaired DNA damage response leading to genome instability. These results, combined with cytogenetic analysis by other authors in this model, suggest that transcriptional profile at passage 14 might induce cytokinesis failure by which tetraploid cells approach a near-tetraploid stage containing primary chromosome aberrations that initiate the tumorigenic drive.

33 CFR 165.911 - Security Zones; Captain of the Port Buffalo Zone.

Code of Federal Regulations, 2010 CFR

2010-07-01

...′ N, 076°23.2′ W; and then following the shoreline back to the point of origin (NAD 83). (2) Ginna... 43°16.7′ N, 077°18.3′ W; then following the shoreline back to starting point (NAD 83). (3) Moses... northwest to 45°00.36′ N, 074°48.16′ W; then northeast back to the starting point (NAD 83). (4) Long Sault...

Determining the Optimal C-130 Deployed Crew Ratio

DTIC Science & Technology

2014-06-13

Bali Internat’l Dominique Ed Osok Pi na ng K am pa...Tari Jalaluddin Pres. Nicolau Sam Ratulangi Pinang Kampai K ia m an a M op ah Sultan Iskandarmuda Gorda Tambolaka Bali Internat’l Dominique Ed Osok...Tambolaka Bali Internat’l Dominique Ed Osok Pi na ng K am pa i Su lta n Is ka nd ar m ud a Tindal Iswahyudi Moses Kilangin Mutiara K ia m an a M op ah

Fuel Effects on Gas Turbine Combustion

DTIC Science & Technology

1983-01-01

consistent with this model. However, the results of an experimental study by Naegeli and Moses [36] suggest that the picture will be more complicated for fuels...It is well established that smoking tendency increases with reduction in hydrogen content [51]. However, it is of interest to note that Naegeli and...Combustion Conditions, J. Eng. Power, "Vol. 102, pp. 403-408, April 1980. 36. Naegeli , D. W. and Effect of Fuel Molecular Structure on C. A. roses, Soot

Oxygenates for Advanced Petroleum-Based Diesel Fuels

DTIC Science & Technology

2001-02-01

needed. Do not return it to the originator. iii Oxygenates for Advanced Petroleum-Based Diesel Fuels INTERIM REPORT TFLRF No. 351 by David W. Naegeli ...Blends,” 219th American Chemical Society Meeting, San Francisco, CA, March 26-30, 2000. 5. Naegeli , D.W. and Moses, C.A., “Effects of Fuel...Alternative Fuels in an Advanced Automotive Diesel Engine,” SAE Paper 2000- 01-2048. 25. Vertin, K.D., Ohi, J.M., Naegeli , D.W., Childress, K.H

Expertise effects in the Moses illusion: detecting contradictions with stored knowledge.

PubMed

Cantor, Allison D; Marsh, Elizabeth J

2017-02-01

People frequently miss contradictions with stored knowledge; for example, readers often fail to notice any problem with a reference to the Atlantic as the largest ocean. Critically, such effects occur even though participants later demonstrate knowing the Pacific is the largest ocean (the Moses Illusion) [Erickson, T. D., & Mattson, M. E. (1981). From words to meaning: A semantic illusion. Journal of Verbal Learning & Verbal Behavior, 20, 540-551]. We investigated whether such oversights disappear when erroneous references contradict information in one's expert domain, material which likely has been encountered many times and is particularly well-known. Biology and history graduate students monitored for errors while answering biology and history questions containing erroneous presuppositions ("In what US state were the forty-niners searching for oil?"). Expertise helped: participants were less susceptible to the illusion and less likely to later reproduce errors in their expert domain. However, expertise did not eliminate the illusion, even when errors were bolded and underlined, meaning that it was unlikely that people simply skipped over errors. The results support claims that people often use heuristics to judge truth, as opposed to directly retrieving information from memory, likely because such heuristics are adaptive and often lead to the correct answer. Even experts sometimes use such shortcuts, suggesting that overlearned and accessible knowledge does not guarantee retrieval of that information.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer

PubMed Central

Zhang, Zhaojing; Yao, Liyong; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming‐Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2017-01-01

Abstract Double layer distribution exists in Cu2SnZnSe4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double‐layer distribution of CZTSe film is eliminated entirely and the formation of MoSe2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSex mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu‐Sn‐Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu2Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm2 and a CZTSe solar cell with efficiency of 7.2% is fabricated. PMID:29610727

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Ramage, Jason K.; Houston, Natalie A.; Johnson, Michaela R.; Schmidt, Tiffany S.

2015-01-01

Compaction of subsurface sediments (mostly in the fine-grained silt and clay layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2014, measured cumulative compaction at the 13 extensometers ranged from 0.101 ft at the Texas City-Moses Lake extensometer to 3.668 ft at the Addicks extensometer. During 2014, a total of 10 of the 13 extensometers recorded a slight net decrease of land-surface elevation; the extensometers at the Lake Houston and Clear Lake (shallow) sites recorded slight net increases of land-surface elevation, and the extensometer at the Texas City-Moses Lake site recorded no change in elevation. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of sand, silt, and clay and compressibilities of the subsurface sediments. It is not appropriate, therefore, to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Rational Design of Hierarchical Nanotubes through Encapsulating CoSe2 Nanoparticles into MoSe2/C Composite Shells with Enhanced Lithium and Sodium Storage Performance.

PubMed

Gao, Jingyu; Li, Yapeng; Shi, Liang; Li, Jingjing; Zhang, Genqiang

2018-06-20

Transition-metal diselenides have been extensively studied as desirable anode candidates for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical capacities. However, it is of great challenge to achieve satisfactory cycling performance, especially for larger sodium ion storage, originated from electrode deterioration upon large volume change. Herein, we reported the construction of hierarchical tubular hybrid nanostructures through encapsulating CoSe 2 nanoparticles into MoSe 2 /C composite shells via a simple two-step strategy including a hydrothermal method followed by vapor-phase selenization process. The unique tubular structure enables the highly reversible Li/Na storage with high specific capacity, enhanced cycling stability, and superior rate performance. It is indicated that the contribution of partial pseudocapacitive behavior greatly improves the rate capability for SIBs, where a high capacity retention of 81.5% can be obtained when the current densities range from 0.1 to 3 A g -1 (460 mA h g -1 at 0.1 A g -1 vs 379 mA h g -1 at 3 A g -1 ). This work provides an effective design rationale on transition-metal diselenide-based tubular nanostructures as superior hosts for both Li and Na ions, which could push forward the development of practical applications of transition-metal diselenide-based anodes in LIBs and SIBs.

Point design targets, specifications, and requirements for the 2010 NIF ignition campaign

NASA Astrophysics Data System (ADS)

Haan, Steven

2010-11-01

A set of point design targets has been specified for the initial ignition campaign on the National Ignition Facility [G. Miller, E. Moses, and C. Wuest, Opt. Eng. 443, 2841 (2004)]. The targets use an ablator of either Be(Cu) or CH(Ge). They are imploded in a U or Au hohlraum at peak radiation temperature 270 to 300eV. Considerations determining the point design include laser-plasma interactions, hydro stability, laser operations, and target fabrication. Simulations were used to evaluate choices, to define requirements, and to estimate sensitivity to uncertainties. Designs were updated to account for 2009 experimental results. We describe a formalism to evaluate the margin for ignition, in a parameter the Ignition Threshold Factor (ITF). Uncertainty and shot-to-shot variability can be evaluated, as well as sensitivity to systematic uncertainties. The formalism is used to estimate the probability of ignition for each target. In collaboration with J Lindl, D Callahan, D Clark, J Salmonson, B Hammel, L Atherton, R Cook, J Edwards, S Glenzer, A Hamza, S Hatchett, D Hinkel, D Ho, O Jones, O Landen, B MacGowan, M Marinak, E Moses, D Munro, S Pollaine, B Spears, P Springer, L Suter, C Thomas, R Town, S Weber, D Wilson, G Kyrala, M Herrmann, R Olson, R Vesey, A Nikroo, H Huang, and K Moreno.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

PubMed

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

Low-resistance 2D/2D ohmic contacts: A universal approach to high-performance WSe 2, MoS 2, and MoSe 2 transistors

DOE PAGES

Chuang, Hsun -Jen; Chamlagain, Bhim; Koehler, Michael; ...

2016-02-04

Here, we report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe 2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~0.3 kΩ μm, high on/off ratios up to >10 9, and high drive currents exceeding 320 μA μm –1. These favorable characteristics are combined with a two-terminal field-effect hole mobility μ FE ≈ 2 × 10 2 cm 2 V –1 smore » –1 at room temperature, which increases to >2 × 10 3 cm 2 V –1 s –1 at cryogenic temperatures. We observe a similar performance also in MoS 2 and MoSe 2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in postsilicon electronics.« less

Regional and local land subsidence at the Venice coastland by TerraSAR-X PSI

NASA Astrophysics Data System (ADS)

Tosi, L.; Strozzi, T.; Da Lio, C.; Teatini, P.

2015-11-01

Land subsidence occurred at the Venice coastland over the 2008-2011 period has been investigated by Persistent Scatterer Interferometry (PSI) using a stack of 90 TerraSAR-X stripmap images with a 3 m resolution and a 11-day revisiting time. The regular X-band SAR acquisitions over more than three years coupled with the very-high image resolution has significantly improved the monitoring of ground displacements at regional and local scales, e.g., the entire lagoon, especially the historical palaces, the MoSE large structures under construction at the lagoon inlets to disconnect the lagoon from the Adriatic Sea during high tides, and single small structures scattered within the lagoon environments. Our results show that subsidence is characterized by a certain variability at the regional scale with superimposed important local displacements. The movements range from a gentle uplift to subsidence rates of up to 35 mm yr-1. For instance, settlements of 30-35 mm yr-1 have been detected at the three lagoon inlets in correspondence of the MoSE works, and local sinking bowls up to 10 mm yr-1 connected with the construction of new large buildings or restoration works have been measured in the Venice and Chioggia historical centers. Focusing on the city of Venice, the mean subsidence of 1.1 ± 1.0 mm yr-1 confirms the general stability of the historical center.

Metabolic Responses to Swimming Exercise in the Infected Rat.

DTIC Science & Technology

1981-06-29

Dunning rats (F-344, F, MA Bioproducts) weighing 150-200 g. ’hey were maintained on a commercial diet (Wayne-Blox, Allied Mills, Inc.) until the...Disease, edited by Kinney and Lense. Columbus, Ohio: Ross Laboratories, 19S0, p. 144-150. 4. BERGSTROM, J., L. HERMANSEN, E. HULITMAN, AND B. SALTIN. Diet ...hepatic ketogenic capacity in fed rats by anti-insulin serum and glucagon. J. Clii:. Invest. 55:1202-1209, 1975. 21. MOSES, 1L. E. Determination of oxygen

Environmental Assessment: Armed Forces Reserve Center Fairchild Air Force Base, Washington

DTIC Science & Technology

2007-01-01

and are a major part of the landscape from the Spokane area southwestward to Moses Lake and as far south as the Columbia River . Soils in the...turkey vulture, Caspian tern , black tern , and osprey. The white-tailed jackrabbit, a state candidate species, is known to occur adjacent to FAFB but... Columbia River Basalt Group. The uppermost basalt is referred to as Basalt A, and the deeper basalt sequence is referred to as Basalt B. The top

KSC-2011-6479

NASA Image and Video Library

2011-08-13

CAPE CANAVERAL, Fla. -- NASA’s Space Shuttle Program Launch Integration Manager Mike Moses speaks to current and former space shuttle workers and their families during the “We Made History! Shuttle Program Celebration,” Aug. 13, at the Kennedy Space Center Visitor Complex, Fla. The event was held to honor shuttle workers’ dedication to the agency’s Space Shuttle Program and to celebrate 30 years of space shuttle achievements. The event featured food, music, entertainment, astronaut appearances, educational activities, giveaways, and Starfire Night Skyshow. Photo credit: Gianni Woods

AGT-1500 Combustor and Fuel Effects Modeling

DTIC Science & Technology

1980-10-01

test data of Moses and Naegeli (1978) were also con- sidered. These comprised blowoff equivalence ratios obtained using Detroit Diesel Allison T-63...Ofoses and Naegeli , 1978) Power Tin P ma 0 T =lp K % K atm kg/sec DRI JP- 5 Gas 100 547 4.77 1.10 .054 .053 .049 2314 2300 2307 55 494 3.69 .93 .069... Naegeli (1978). Their ignition tests were conducted on the T-63 helicopter engine (can-type comb~ustor with the igniter located in the dome) with 13

Development of Technologies for Early Detection and Stratification of Breast Cancer

DTIC Science & Technology

2014-10-01

cancer. Similar screening has been done in urine samples with CYR61 and LCN2 (Figure 2a-b). The Moses lab provided breast cancer urine samples and two ...diseased samples, while CYR61 appears to have two different populations whereas diseased urine samples have lower levels of the protein present. More... system for eDAR so that each isolated cell can be deposited into a well of a 96-well plate for high-throughput downstream single-cell digital

Digital Transfer Growth of Patterned 2D Metal Chalcogenides by Confined Nanoparticle Evaporation

DOE PAGES

Mahjouri-Samani, Masoud; Tian, Mengkun; Wang, Kai; ...

2014-10-19

Developing methods for the facile synthesis of two-dimensional (2D) metal chalcogenides and other layered materials is crucial for emerging applications in functional devices. Controlling the stoichiometry, number of the layers, crystallite size, growth location, and areal uniformity is challenging in conventional vapor phase synthesis. Here, we demonstrate a new route to control these parameters in the growth of metal chalcogenide (GaSe) and dichalcogenide (MoSe 2) 2D crystals by precisely defining the mass and location of the source materials in a confined transfer growth system. A uniform and precise amount of stoichiometric nanoparticles are first synthesized and deposited onto a substratemore » by pulsed laser deposition (PLD) at room temperature. This source substrate is then covered with a receiver substrate to form a confined vapor transport growth (VTG) system. By simply heating the source substrate in an inert background gas, a natural temperature gradient is formed that evaporates the confined nanoparticles to grow large, crystalline 2D nanosheets on the cooler receiver substrate, the temperature of which is controlled by the background gas pressure. Large monolayer crystalline domains (~ 100 m lateral sizes) of GaSe and MoSe 2 are demonstrated, as well as continuous monolayer films through the deposition of additional precursor materials. This novel PLD-VTG synthesis and processing method offers a unique approach for the controlled growth of large-area, metal chalcogenides with a controlled number of layers in patterned growth locations for optoelectronics and energy related applications.« less

Clinical career ladders: the Moses H. Cone Memorial Hospital.

PubMed

Crouch, J B; Douglas, J B; Wheeler, D S

1989-11-01

A competence- and achievement-based advancement program developed for pharmacists at The Moses H. Cone Memorial Hospital, a 530-bed community teaching hospital, is described. In 1985 pharmacy management recognized the need to provide an incentive program to reward achievements by staff clinical pharmacists, recognize their increased responsibilities, and increase the department's ability to retain qualified practitioners. Adding another rung to the existing administrative career ladder was not desirable, so a new job category, pharmacist II, was created. Employees are evaluated for promotion to pharmacist II on the basis of tenure, performance, and elective professional and service activities. A point system is used to objectively score achievements; to be promoted, an employee must accumulate 50 points during a two-year period. The number of staff pharmacists who can advance is limited not arbitrarily but rather by the application of challenging criteria. Employees are responsible for submitting documentation of their achievements to a review committee, which meets quarterly to evaluate applications and award points. Of 13 applicants since 1985, 10 have been promoted. Because of problems in evaluating the performance of pharmacist II employees, providing them time to conduct research, and incorporating specialty practice areas into the program, plans are being made to institute a more structured career ladder system with separate managerial, clinical, and educational tracks. A competence- and achievement-based advancement program with a single step was an improvement over the former system but lacked the balance and comprehensiveness offered by more structured career ladder programs.

Electronic and magnetic properties of MoSe2 armchair nanoribbons controlled by the different edge structures

NASA Astrophysics Data System (ADS)

Zhang, Hui; Zhao, Xu; Gao, Yonghui; Wang, Haiyang; Wang, Tianxing; Wei, Shuyi

2018-03-01

Tow-dimensional materials obviously have potential applications in next-generation nanodevices because of their extraordinary physical and chemical properties and the demands of the market. Using first-principle calculation based on density functional theory, we explore electronic and magnetic properties of the different nanoribbons with various edge structures, namely, with hydrogenation or not. In addition, we also calculate the binding energy to analyze the stability of the nanoribbon. Our calculations tell us that the passivated nanoribbons have the positive binding energies, which indicates the passivated nanoribbons are relative stable and hydrogenation can improve the stability of the bare nanoribbons due to the reduction of the dangling bonds. Among of them, full hydrogenation has the highest stability. We find all the nanoribbons with full and without hydrogenation are nonmagnetic semiconductors. It is worth mentioning that hydrogenation can induce the bare nanoribbons to transform gradually from indirect band gap semiconductor to direct band gap semiconductor, even to half-metal. In addition, the magnetic moment of the bare nanoribbon change bit by bit as the rate of hydrogenation increases. When the edge atoms are fully hydrogenated, the magnetic moment return to zero. What's more, our research results still confirm that electronic and magnetic properties of the nanorribons without and with different edge passivation are mainly contributed by the atoms at the edges. These studies about MoSe2 nanoribbons will shed light on the further development of the relevant nanodevices in versatile applications, such as spintronics and energy harvesting.

Confined lattice dynamics of single and quadruple SnSe bilayers in [(SnSe) 1.04 ] m [MoSe 2 ] n ferecrystals

DOE PAGES

Klobes, Benedikt; Hu, Michael Y.; Beekman, Matt; ...

2015-11-30

The Sn specific densities of phonon states in the SnSe subunits of [(SnSe) 1.04] m[MoSe 2] n ferecrystals with (m,n) = (1,1), (4,1) and in bulk SnSe were derived from nuclear inelastic scattering by the 119Sn M ssbauer resonance. When using different measurement configurations, phonons with polarization parallel and perpendicular to the ferecrystal plane were specifically probed. Vibrational properties and phonon spectral weight are found to strongly depend on the phonon polarization and layer count m. Moreover, a highly peculiar feature of these ferecrystal densities of phonon states is the emergence of rather sharp high energy vibrational modes polarized perpendicularmore » to the ferecrystal plane, which contrasts with usual findings in thin layered structures and nanostructured materials in general, and a depletion of modes with a gap appearing between acoustic and high energy modes. The spectral weight of these phonons depends on the overall SnSe content, m, but cannot be unambiguously attributed to SnSe MoSe 2 interfaces. Considering the low energy part of lattice dynamics, ferecrystals exhibit rather low average phonon group velocities as compared to the speed of sound in the long wavelength limit. For the (1,1) ferecrystal, this effect is most pronounced for vibrations polarized in the ferecrystal plane. Therefore, an experimental microscopic origin for the vibrational and bonding anisotropy in subunits of ferecrystals is provided.« less

Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafarman, William N.

This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phasemore » agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.« less

Prospects of Two-Dimensional Devices: Electrical and Optical Characterization of Transition Metal Dichalcogenide Films

NASA Astrophysics Data System (ADS)

Klee, Velveth

Understanding the electrical and optical properties of 2D materials down to their monolayer limit is important for establishing their potential for novel applications. Prominent among 2D materials are transition metal dichalcogenides (TMDs), such as MoS2 and MoSe2. These materials have attracted attention because of their intriguing properties, such as a transition from an indirect bandgap for few layers to a direct bandgap for monolayers. New synthetic routes like chemical vapor deposition (CVD) allow for high-quality, centimeter-scale growth and tuning of the direct optical gap continuously between the values of single-layer MoS2 (1.87eV) and MoSe 2 (1.55eV). In the first part of this work, we perform optoelectronic measurements of alloy devices fabricated on CVD-grown, monolayer MoS2, MoS 2(1-x)Se2x, and MoSe2 islands. For all alloy compositions there is an unusual superlinear dependence of the photocurrent on light intensity. We also establish the photoconductive nature of the photoresponse, with the photocurrent originating from recombination and field-induced carrier separation in the channel. The study of transport characteristics of TMDs is extended to explore the effects of devices on a piezoelectric substrate as a route towards establishing fabrication processes suited for industry. In this work, we show that CVD-growth of MoS2 monolayer films onto periodically poled lithium niobate is possible while maintaining the substrate polarization pattern. Electrical transport measurements indicate an inversion of the MoS2 from n-type to p-type behavior under application of an external voltage depending on the domain orientation of the ferroelectric substrate. Sensitivity to ferroelectric substrate polarization opens the possibility for ferroelectric nonvolatile gating of TMDs in scalable devices fabricated free of exfoliation and transfer. Optimizing CVD techniques allows for preparation of TMD films in different phases that are reported to exhibit semiconducting and metallic properties. Here, we show optical and electronic characterization of few-layer films of MoTe2 in three distinct structural phases: 2H, 1T' and 1T. Depending on process parameters, either of the phases can be prepared using MoO3 and elemental tellurium precursors. Experimental and computed Raman spectra are presented for each phase. Transport measurements validate predictions from DFT-based band structure calculations on the metallic character of the centrosymmetric 1T phase.

A Historical Analysis of Three Main Issues Affecting United States Foreign Policy in the Middle East

DTIC Science & Technology

1979-06-01

Engineers, in-country English language training, organizational and intermediate maintenance, and supply modernization (78). Foreign Military Sales (FMS... Bible is a history of the Jewish people and their religion. Moses, 80 -• ’E’ I I I I I I I I I I I I I I I I i I. the prophet who freed the Jews from...Egypt, presented the Ten Commandments that are followed by both religions. The Christian Bible and the Jewish Torah both relate in the Book of Genesis

Fire Safety Tests Comparing Synthetic Jet and Diesel Fuels with JP-8 (POSTPRINT)

DTIC Science & Technology

2010-04-01

about 25% aromatics and 75% saturated (paraffin and naphthene ) hydro- carbons [5]. JP-8 is produced from jet fuel A by adding a corrosion inhibitor...4529a 43.9 44.2 Lubricity (mm) ASTM D – 5001 0.58 0.92 Acidity (mg KOH/g) ASTM D – 3242 0.004 0.003 SPK fuels taken from Moses [7], diesel fuels taken...this occurred the burnback pan was removed from the agent pan. The flames in the agent pan were allowed to break up the foam blanket and propagate until

Development of the silane process for the production of low-cost polysilicon

NASA Technical Reports Server (NTRS)

Iya, S. K.

1986-01-01

It was recognized that the traditional hot rod type deposition process for decomposing silane is energy intensive, and a different approach for converting silane to silicon was chosen. A 1200 metric tons/year capacity commercial plant was constructed in Moses Lake, Washington. A fluidized bed processor was chosen as the most promising technology and several encouraging test runs were conducted. This technology continues to be very promising in producing low cost polysilicon. The Union Carbide silane process and the research development on the fluidized bed silane decomposition are discussed.

Minority Participation and Retention in Higher Education. Hearing on Examining Certain Issues Relating to Minority Participation in Higher Education, Focusing on Student Aid Programs before the Subcommittee on Education, Arts, and Humanities of the Committee on Labor and Human Resources. United States Senate, One Hundred Third Congress, Second Session.

ERIC Educational Resources Information Center

Congress of the U.S., Washington, DC. Senate Subcommittee on Education, Arts and Humanities.

This hearing transcript presents testimony concerning minority participation and retention in higher education with emphasis on implications for student aid programs. Oral testimony or prepared statements were presented by Senators Paul Simon, Claiborne Pell, and Carol Mosely-Braun. Testimony was also offered by: (1) the president and three…

Military Fuels Refined from Paraho-II Shale Oil.

DTIC Science & Technology

1981-03-01

FUELS REFINED O FROM PARAHO-II SHALE OIL INTERIM REPORT AFLRL No. 131 4!t by J.N. Bowden E.C. Owens D.W. Naegeli L.L. Stavinoha U.S. Army Fuels and...J.N./Bowden, E.C. /Owens, D.W./ Naegeli / DAAK70-78-C-0001 € L.L. Stavinoha DAAK70-80-C-0001 V 9 PERFORMING ORGANIZATION NAME AND ADDRESSES J0...Combustor Design and Oper- ating Conditions," Combustion Science and Technology, 19, 119, 1979. 16. Moses, C.A., and Naegeli , D.W., "Fuel Property

"Academic racism" and the neglected scholarship of the anatomist M. Wharton Young, MD, PhD (1904-1986).

PubMed

Heywood, Peter

2018-02-01

Moses Wharton Young, MD, PhD (1904-1986), was an African American Professor of Neuroanatomy at Howard University College of Medicine from 1934 to 1973, during which time he authored about 100 publications on topics that included baldness, asthma, glaucoma, and, most importantly, the structure and function of the inner ear and the pathophysiology of blast injuries. Much of Young's research was ignored during his lifetime, raising the question whether this professional neglect was an instance of "academic racism."

High resolution statistical downscaling of the EUROSIP seasonal prediction. Application for southeastern Romania

NASA Astrophysics Data System (ADS)

Busuioc, Aristita; Dumitrescu, Alexandru; Dumitrache, Rodica; Iriza, Amalia

2017-04-01

Seasonal climate forecasts in Europe are currently issued at the European Centre for Medium-Range Weather Forecasts (ECMWF) in the form of multi-model ensemble predictions available within the "EUROSIP" system. Different statistical techniques to calibrate, downscale and combine the EUROSIP direct model output are used to optimize the quality of the final probabilistic forecasts. In this study, a statistical downscaling model (SDM) based on canonical correlation analysis (CCA) is used to downscale the EUROSIP seasonal forecast at a spatial resolution of 1km x 1km over the Movila farm placed in southeastern Romania. This application is achieved in the framework of the H2020 MOSES project (http://www.moses-project.eu). The combination between monthly standardized values of three climate variables (maximum/minimum temperatures-Tmax/Tmin, total precipitation-Prec) is used as predictand while combinations of various large-scale predictors are tested in terms of their availability as outputs in the seasonal EUROSIP probabilistic forecasting (sea level pressure, temperature at 850 hPa and geopotential height at 500 hPa). The predictors are taken from the ECMWF system considering 15 members of the ensemble, for which the hindcasts since 1991 until present are available. The model was calibrated over the period 1991-2014 and predictions for summers 2015 and 2016 were achieved. The calibration was made for the ensemble average as well as for each ensemble member. The model was developed for each lead time: one month anticipation for June, two months anticipation for July and three months anticipation for August. The main conclusions from these preliminary results are: best predictions (in terms of the anomaly sign) for Tmax (July-2 months anticipation, August-3 months anticipation) for both years (2015, 2016); for Tmin - good predictions only for August (3 months anticipation ) for both years; for precipitation, good predictions for July (2 months anticipation) in 2015 and August (3 months anticipation) in 2016; failed prediction for June (1-month anticipation) for all parameters. To see if the results obtained for 2015 and 2016 summers are in agreement with the general ECMWF model performance in forecast of the three predictors used in the CCA SDM calibration, the mean bias and root mean square errors (RMSE) calculated over the entire period in each grid point, for each ensemble member and ensemble average were computed. The obtained results are confirmed, showing highest ECMWF performance in forecasting of the three predictors for 3 months anticipation (August) and lowest performance for one month anticipation (June). The added value of the CCA SDM in forecasting local Tmax/Tmin and total precipitation was compared to the ECMWF performance using nearest grid point method. Comparisons were performed for the 1991-2014 period, taking into account the forecast made in May for July. An important improvement was found for the CCA SDM predictions in terms of the RMSE value (computed against observations) for Tmax/Tmin and less for precipitation. The tests are in progress for the other summer months (June, July).

Effect of Metal Doping and Vacancies on the Thermal Conductivity of Monolayer Molybdenum Diselenide.

PubMed

Yarali, Milad; Brahmi, Hatem; Yan, Zhequan; Li, Xufan; Xie, Lixin; Chen, Shuo; Kumar, Satish; Yoon, Mina; Xiao, Kai; Mavrokefalos, Anastassios

2018-02-07

It is well understood that defect engineering can give rise to exotic electronic properties in transition-metal dichalcogenides, but to this date, there is no detailed study to illustrate how defects can be engineered to tailor their thermal properties. Here, through combined experimental and theoretical approaches based on the first-principles density functional theory and Boltzmann transport equations, we have explored the effect of lattice vacancies and substitutional tungsten (W) doping on the thermal transport of the suspended molybdenum diselenide (MoSe 2 ) monolayers grown by chemical vapor deposition (CVD). The results show that even though the isoelectronic substitution of the W atoms for Mo atoms in CVD-grown Mo 0.82 W 018 Se 2 monolayers reduces the Se vacancy concentration by 50% compared to that found in the MoSe 2 monolayers, the thermal conductivity remains intact in a wide temperature range. On the other hand, Se vacancies have a detrimental effect for both samples and more so in the Mo 0.82 W 018 Se 2 monolayers, which results in thermal conductivity reduction up to 72% for a vacancy concentration of 4%. This is because the mass of the W atom is larger than that of the Mo atom, and missing a Se atom at a vacancy site results in a larger mass difference and therefore kinetic energy and potential energy difference. Furthermore, the monotonically increasing thermal conductivity with temperature for both systems at low temperatures indicates the importance of boundary scattering over defects and phonon-phonon scattering at these temperatures.

Comparison of PM10 concentrations and metal content in three different sites of the Venice Lagoon: an analysis of possible aerosol sources.

PubMed

Contini, Daniele; Belosi, Franco; Gambaro, Andrea; Cesari, Daniela; Stortini, Angela Maria; Bove, Maria Chiara

2012-01-01

The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified.

A review of the genus Agapetus Curtis (Trichoptera: Glossosomatidae) in eastern and central North America, with description of 12 new species

USGS Publications Warehouse

Etnier, David A.; Parker, Charles R.; Baxter, John T.; Long, Todd M.

2010-01-01

Twenty-nine species of caddisflies in the genus Agapetus Curtis in eastern and central North America are reviewed. Twelve are described as new species: Agapetus aphallus (known only from females); Agapetus baueri, Agapetus flinti, Agapetus harrisi, Agapetus hesperus, Agapetus ibis, Agapetus kirchneri, Agapetus meridionalis, Agapetus pegram, Agapetus ruiteri, Agapetus stylifer, and Agapetus tricornutus. Agapetus rossi Denning 1941 is recognized as a junior subjective synonym of Agapetus walkeri (Betten and Mosely 1940), new synonym. A key to males is provided, and species’ distributions are mapped.

Photodissociation Cross Sections and Spectroscopy of Atmospheric Positive Ions

DTIC Science & Technology

1979-03-13

MP 79-1 * ATNR~ e _____________________ CONTRAg T’. NUMNER(s) G. P. Smith, L. C. Lee, P. CCobJ. R. I . DA 9--C- /EPeter o J.: T.1 MoseASy PEFRMN...Photodissociation of positive ions can be an important power-loss process in e -beam and gas discharge lasers, and a genctal model should prove useful...monJel ca.l)olatioa i detibed is, Apm4i 0, 4 PHOTON ENERGY (eV) 1.5 2.0 2.5 3.0 3.5 24k NONO+ E 20E °This work Vanderhoff 0 . -Model calculation 16- z 0_ m

Atomically thin resonant tunnel diodes built from synthetic van der Waals heterostructures.

PubMed

Lin, Yu-Chuan; Ghosh, Ram Krishna; Addou, Rafik; Lu, Ning; Eichfeld, Sarah M; Zhu, Hui; Li, Ming-Yang; Peng, Xin; Kim, Moon J; Li, Lain-Jong; Wallace, Robert M; Datta, Suman; Robinson, Joshua A

2015-06-19

Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2). The realization of MoS2-WSe2-graphene and WSe2-MoS2-graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics.

[Notes for a History of Hygiene taken from the Bible].

PubMed

Ledermann, Walter

2016-08-01

Reading once more the Gospels, we found a discussion between Jesus and the Pharisee about the hand washing, this golden rule of medicine, and then, with the help of Thomas Mann, we began a search for other notes on hygiene in the Bible. For the return from Egypt to the Promised Land, Moses established several rules for his people, some of them disguised as religious principles, concerning elimination of excreta, healthy and poisonous foods, isolation in case of contagious diseases (leprosy, gonorrhea), decontamination of clothes and houses, and many others that now seem to us ahead his time.

Piezoelectric coefficients of bulk 3R transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Konabe, Satoru; Yamamoto, Takahiro

2017-09-01

The piezoelectric properties of bulk transition metal dichalcogenides (TMDCs) with a 3R structure were investigated using first-principles calculations based on density functional theory combined with the Berry phase treatment. Values for the elastic constant Cijkl , the piezoelectric coefficient eijk , and the piezoelectric coefficient dijk are given for bulk 3R-TMDCs (MoS2, MoSe2, WS2, and WSe2). The piezoelectric coefficients of bulk 3R-TMDCs are shown to be sufficiently large or comparable to those of conventional bulk piezoelectric materials such as α-quartz, wurtzite GaN, and wurtzite AlN.

Light Propagation Through Transition Metal Dichalcogenides

NASA Astrophysics Data System (ADS)

Stevens, Christopher; Paul, Jagannath; Zhang, Haoxiang; Stier, Andreas; Karaiskaj, Denis

C.E.STEVENS,J.PAUL,H.ZHANG, Dept. of Physics, University of South Florida, Tampa, Florida 33620, USA. A.V.STIER, National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, D. KARAISKAJ, Dept. of Physics, University of South Florida, Tampa, Florida 33620, USA. - Using broadband light, the propagation of light through MoSe2 and WSe2 was investigated. Measuring the optical density for samples with different number of layers, we found that these values differ from what the Beer-Lambert Law predicts. The results were also modeled theoretically according to an effective two-band model. Funded by The Department of Energy.

Trion formation dynamics in monolayer transition metal dichalcogenides

DOE PAGES

Singh, Akashay; Moody, Galan; Schaibley, John R.; ...

2016-01-05

Here, we report charged exciton (trion) formation dynamics in doped monolayer transition metal dichalcogenides, specifically molybdenum diselenide (MoSe 2), using resonant two-color pump-probe spectroscopy. When resonantly pumping the exciton transition, trions are generated on a picosecond time scale through exciton-electron interaction. As the pump energy is tuned from the high energy to low energy side of the inhomogeneously broadened exciton resonance, the trion formation time increases by ~50%. This feature can be explained by the existence of both localized and delocalized excitons in a disordered potential and suggests the existence of an exciton mobility edge in transition metal dichalcogenides.

The encounter with God in myth and madness.

PubMed

Doerr, Otto; Velásquez, Oscar

2007-07-03

It is well known how often psychiatric patients report religious experiences. These are especially frequent in schizophrenic and epileptic patients as the subject of their delusions. The question we pose is: are there differences between this kind of religious experiences and those we find in religious texts or in the mythological tradition? An overview on famous mythological narratives, such as The Aeneid, allows us to establish that the divinities become recognizable to the human being at the moment of their departure. Thus, Aeneas does not recognise his mother, Venus, when she appears to him in the middle of the forest at the coast of Africa. A dialogue between the two takes place, and only at the end of the encounter, when she is going away and already with her back to Aeneas, she shows her son the signs of her divinity: the rose-flush emanating from her neck, her hair perfume and the majesty of her gait. Something analogous can be observed in the encounter of Moses with Yahweh on Mount Sinai. Moses asks God: "Show me your glory, I beg you". And God replies, among other things: "you shall see the back of me, but my face is not to be seen". In the same sense, the Emmaus disciples do not recognise Jesus till the moment of his disappearance ("but he had vanished from their sight"), and Saul of Tars falls off his horse just in the moment when he feels the divine presence. In short, the direct encounter with the divinity seems not to occur in the realm of myth or in religious tradition. The realm of madness is exactly the opposite. Our research on religious experiences in schizophrenic and epileptic patients leads us to conclude that God appears to them face to face, and the patient describes God the father, Jesus or the Virgin Mary in intimate detail, always in an everyday setting. So, the divinity is seen in the garden, or in the bedroom, or maybe above the wardrobe, without any of its majesty. The nearness to God also tends to be so extreme that even an identification of patient and God can occur. That light emanating from the world of the divine ceases to be perceived by them. While in mythological narratives God appears to the human being at the moment of His departure or showing His back, psychiatric patients with religious delusions experience the divinity in a direct way, face to face. Given the deformation of the divine occurring on the edge of madness we can better understand the mysterious words from Yahweh to Moses in Exodus: "for man cannot see me and live".

The encounter with God in myth and madness

PubMed Central

Doerr, Otto; Velásquez, Óscar

2007-01-01

Background It is well known how often psychiatric patients report religious experiences. These are especially frequent in schizophrenic and epileptic patients as the subject of their delusions. The question we pose is: are there differences between this kind of religious experiences and those we find in religious texts or in the mythological tradition? Results An overview on famous mythological narratives, such as The Aeneid, allows us to establish that the divinities become recognizable to the human being at the moment of their departure. Thus, Aeneas does not recognise his mother, Venus, when she appears to him in the middle of the forest at the coast of Africa. A dialogue between the two takes place, and only at the end of the encounter, when she is going away and already with her back to Aeneas, she shows her son the signs of her divinity: the rose-flush emanating from her neck, her hair perfume and the majesty of her gait. Something analogous can be observed in the encounter of Moses with Yahweh on Mount Sinai. Moses asks God: "Show me your glory, I beg you". And God replies, among other things: "you shall see the back of me, but my face is not to be seen". In the same sense, the Emmaus disciples do not recognise Jesus till the moment of his disappearance ("but he had vanished from their sight"), and Saul of Tars falls off his horse just in the moment when he feels the divine presence. In short, the direct encounter with the divinity seems not to occur in the realm of myth or in religious tradition. The realm of madness is exactly the opposite. Our research on religious experiences in schizophrenic and epileptic patients leads us to conclude that God appears to them face to face, and the patient describes God the father, Jesus or the Virgin Mary in intimate detail, always in an everyday setting. So, the divinity is seen in the garden, or in the bedroom, or maybe above the wardrobe, without any of its majesty. The nearness to God also tends to be so extreme that even an identification of patient and God can occur. That light emanating from the world of the divine ceases to be perceived by them. Conclusion While in mythological narratives God appears to the human being at the moment of His departure or showing His back, psychiatric patients with religious delusions experience the divinity in a direct way, face to face. Given the deformation of the divine occurring on the edge of madness we can better understand the mysterious words from Yahweh to Moses in Exodus: "for man cannot see me and live". PMID:17608933

The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kowalczyk, Eva A.; Stevens, Lauren E.; Law, Rachel M.

The Community Atmosphere Biosphere Land Exchange (CABLE) model has been coupled to the UK Met Office Unified Model (UM) within the existing framework of the Australian Community Climate and Earth System Simulator (ACCESS), replacing the Met Office Surface Exchange Scheme (MOSES). Here we investigate how features of the CABLE model impact on present-day surface climate using ACCESS atmosphere-only simulations. The main differences attributed to CABLE include a warmer winter and a cooler summer in the Northern Hemisphere (NH), earlier NH spring runoff from snowmelt, and smaller seasonal and diurnal temperature ranges. The cooler NH summer temperatures in canopy-covered regions aremore » more consistent with observations and are attributed to two factors. Firstly, CABLE accounts for aerodynamic and radiative interactions between the canopy and the ground below; this placement of the canopy above the ground eliminates the need for a separate bare ground tile in canopy-covered areas. Secondly, CABLE simulates larger evapotranspiration fluxes and a slightly larger daytime cloud cover fraction. Warmer NH winter temperatures result from the parameterization of cold climate processes in CABLE in snow-covered areas. In particular, prognostic snow density increases through the winter and lowers the diurnally resolved snow albedo; variable snow thermal conductivity prevents early winter heat loss but allows more heat to enter the ground as the snow season progresses; liquid precipitation freezing within the snowpack delays the building of the snowpack in autumn and accelerates snow melting in spring. Altogether we find that the ACCESS simulation of surface air temperature benefits from the specific representation of the turbulent transport within and just above the canopy in the roughness sublayer as well as the more complex snow scheme in CABLE relative to MOSES.« less

Synthesis, characterization and optical non-linearity of two heterobimetallic copper clusters containing tetraselenometalates

NASA Astrophysics Data System (ADS)

Zhang, Qian-Feng; Zhang, Chi; Song, Ying-Lin; Xin, Xin-Quan

2000-07-01

Cluster [{MoCu 3Se 3Br}(PPh 3) 3Se]·3THF·H 2O ( 1·3THF·H 2O) was prepared from reaction of [Et 4N] 2[MoSe] 4, Cu(PPh 3) 2NO 3 and Et 4N·Br in CH 2Cl 2 solution; also, 1 can be also obtained from the reaction of [MoSe 4Cu 4Py 6Br 2] and excess PPh 3 in a DMF-CH 2Cl 2 mixture solvent. The 95Mo NMR technique was used to monitor the above two reaction processes. X-ray crystallographic structure determination shows that it contains a strongly distorted cubane-like {MoCu 3Se 3Br} core. The coordination of the central Mo atom and each Cu atom are distorted from tetrahedral. Cluster [{WCu 3Se 3Cl}(PPh 3) 3Se] ( 2) was synthesized by the reaction of [Et 4N] 2[WSe] 4 and Cu(PPh 3) 2Cl in the solid state for nonlinear optical (NLO) studies. Its structure was reported by Ibers (Inorg. Chem. 31 (1992) 4365). The NLO properties of clusters 1 and 2 were studied. Both NLO absorption and refraction were obtained, and their effective third-order non-linearities were detected with α2=3.4×10 -10 and 5.9×10 -10 m/W and n2=-1.5×10 -17 and -1.3×10 -17 m 2/W , respectively, for the same concentration CH 2Cl 2 solution of 1 and 2. Influence of skeletal atoms to nonlinear absorption is also discussed in the paper.

Comparison between innominate osteotomy and arthrodistraction as a primary treatment for Legg-Calvé-Perthes disease: a prospective controlled trial.

PubMed

Volpon, José Batista

2012-09-01

Legg-Calvé-Perthes (LCP) disease is currently managed by mechanical containment of the femoral head in the hip socket. As evidence suggests that hip distraction may offer a new treatment strategy, we used arthrodistraction as a primary treatment for active forms of LCP disease and prospectively compared the results with the Salter innominate osteotomy. A total of 54 children, six years or older of both genders with severe forms of LCP disease in the stages of necrosis or revascularisation, were enrolled. Patients were submitted to either Salter innominate osteotomy (n = 28) or hip arthrodistraction (n = 26). Final radiographs were used to evaluate the Mose index, Wiberg angle, extrusion index and the Stulberg et al. classification. There were no significant differences in gender, age, lateral pillar classification and average follow-up time between the two groups. The osteotomy group progressed without major complications, but children in the joint distraction group experienced episodes of pin tract pain and infection, leading to the early removal of the external device in one case. Two patients developed joint stiffness, treated by physiotherapy or manipulation, and one child developed subluxation of the femoral head. The average time in distraction was 4.44 months (2.53-7.23 months). In the final evaluation the osteotomy group showed better containment of the femoral head. The Mose index and the Stulberg et al. classification were statistically similar between the two groups. Despite similar final radiological results, arthrodistraction was associated with a higher morbidity. Consequently, we do not recommend hip distraction as a primary treatment for the early stages of LCP disease.

The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology

DOE PAGES

Kowalczyk, Eva A.; Stevens, Lauren E.; Law, Rachel M.; ...

2016-08-23

The Community Atmosphere Biosphere Land Exchange (CABLE) model has been coupled to the UK Met Office Unified Model (UM) within the existing framework of the Australian Community Climate and Earth System Simulator (ACCESS), replacing the Met Office Surface Exchange Scheme (MOSES). Here we investigate how features of the CABLE model impact on present-day surface climate using ACCESS atmosphere-only simulations. The main differences attributed to CABLE include a warmer winter and a cooler summer in the Northern Hemisphere (NH), earlier NH spring runoff from snowmelt, and smaller seasonal and diurnal temperature ranges. The cooler NH summer temperatures in canopy-covered regions aremore » more consistent with observations and are attributed to two factors. Firstly, CABLE accounts for aerodynamic and radiative interactions between the canopy and the ground below; this placement of the canopy above the ground eliminates the need for a separate bare ground tile in canopy-covered areas. Secondly, CABLE simulates larger evapotranspiration fluxes and a slightly larger daytime cloud cover fraction. Warmer NH winter temperatures result from the parameterization of cold climate processes in CABLE in snow-covered areas. In particular, prognostic snow density increases through the winter and lowers the diurnally resolved snow albedo; variable snow thermal conductivity prevents early winter heat loss but allows more heat to enter the ground as the snow season progresses; liquid precipitation freezing within the snowpack delays the building of the snowpack in autumn and accelerates snow melting in spring. Altogether we find that the ACCESS simulation of surface air temperature benefits from the specific representation of the turbulent transport within and just above the canopy in the roughness sublayer as well as the more complex snow scheme in CABLE relative to MOSES.« less

The two time vectors of Nachträglichkeit in the development of ego organization: significance of the concept for the symbolization of nameless traumas and anxieties.

PubMed

Dahl, Gerhard

2010-08-01

The author describes Freud 's conception of Nachträglichkeit as an active process that bridges the gap between past affective vicissitudes and the cognitive present by way of meaning. Symbolization is thereby subsequently [nachträglich] conferred on early traumatic events, which thus become susceptible to omnipotent control. The two time vectors of Nachträglichkeit are discussed: the first is a causal process operating in the forward direction of time against the background of a factual reality, while the second is a backward movement that permits an understanding of unconscious scenes and phantasies taking place at primary-process level. This twofold temporal motion was observed and described by Freud early on. However, its significance often remained hidden prior to his study of Moses. It was mostly overlooked in English and French translations, thus giving rise to a one-sided understanding of the concept in the various psychoanalytic cultures, as either deferred action or après-coup. Freud 's Moses study addresses both temporal aspects of Nachträglichkeit, seeking not only to reconstruct a past event on a causal, deterministic basis, but also to understand the subjective truth of that event in the transference along the retrograde time line. The decisive criterion for the conceptual and clinical separation of the two time vectors is the development of ego organization and the capacity for symbolization. The two vectors should not be separated on the factual level, as both aspects of Nachträglichkeit are essential to the understanding of unconscious processes, combining as they do in a relationship of circular complementarity. © 2009 Institute of Psychoanalysis.

Ultrasensitive sensing platform for platelet-derived growth factor BB detection based on layered molybdenum selenide-graphene composites and Exonuclease III assisted signal amplification.

PubMed

Huang, Ke-Jing; Shuai, Hong-Lei; Zhang, Ji-Zong

2016-03-15

A highly sensitive and ultrasensitive electrochemical aptasensor for platelet-derived growth factor BB (PDGF-BB) detection is fabricated based on layered molybdenum selenide-graphene (MoSe2-Gr) composites and Exonuclease III (Exo III)-aided signal amplification. MoSe2-Gr is prepared by a simple hydrothermal method and used as a promising sensing platform. Exo III has a specifical exo-deoxyribonuclease activity for duplex DNAs in the direction from 3' to 5' terminus, however its activity is limited on the duplex DNAs with more than 4 mismatched terminal bases at 3' ends. Herein, aptamer and complementary DNA (cDNA) sequences are designed with four thymine bases on 3' ends. In the presence of target protein, the aptamer associates with it and facilitates the formation of duplex DNA between cDNA and signal DNA. The duplex DNA then is digested by Exo III and releases cDNA, which hybridizes with signal DNA to perform a new cleavage process. Nevertheless, in the absence of target protein, the aptamer hybridizes with cDNA will inhibit the Exo III-assisted nucleotides cleavage. The signal DNA then hybridizes with capture DNA on the electrode. Subsequently, horse radish peroxidase is fixed on electrode by avidin-biotin reaction and then catalyzes hydrogen peroxide and hydroquinone to produce electrochemical response. Therefore, a bridge can be established between the concentration of target protein and the degree of the attenuation of the obtained signal, providing a quantitative measure of target protein with a broad detection range of 0.0001-1 nM and a detection limit of 20 fM. Copyright © 2015 Elsevier B.V. All rights reserved.

A revision of the Neotropical caddisfly genus Leucotrichia Mosely, 1934 (Hydroptilidae, Leucotrichiinae)

PubMed Central

Thomson, Robin E.; Holzenthal, Ralph W.

2015-01-01

Abstract A revision of Leucotrichia (Trichoptera, Hydroptilidae) is provided, including a generic diagnosis, illustrations, a key, and descriptions of males. A total of 43 species are treated, 13 described as new: Leucotrichia angelinae sp. n. (Venezuela), Leucotrichia denticulata sp. n. (Mexico), Leucotrichia dianeae sp. n (Costa Rica), Leucotrichia fulminea sp. n. (Ecuador), Leucotrichia hispida sp. n. (Costa Rica), Leucotrichia kateae sp. n. (Venezuela), Leucotrichia pectinata sp. n. (Ecuador), Leucotrichia procera sp. n. (Brazil), Leucotrichia repanda sp. n. (Venezuela), Leucotrichia rhomba sp. n. (Costa Rica), Leucotrichia riostoumae sp. n. (Ecuador), Leucotrichia sidneyi sp. n. (Venezuela), and Leucotrichia tapantia sp. n. (Costa Rica). PMID:25931968

Atomically thin resonant tunnel diodes built from synthetic van der Waals heterostructures

PubMed Central

Lin, Yu-Chuan; Ghosh, Ram Krishna; Addou, Rafik; Lu, Ning; Eichfeld, Sarah M.; Zhu, Hui; Li, Ming-Yang; Peng, Xin; Kim, Moon J.; Li, Lain-Jong; Wallace, Robert M.; Datta, Suman; Robinson, Joshua A.

2015-01-01

Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2). The realization of MoS2–WSe2–graphene and WSe2–MoS2–graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics. PMID:26088295

The role of electron-phonon interactions on the coherence lifetime of monolayer transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Stevens, C. E.; Dey, P.; Paul, J.; Wang, Z.; Zhang, H.; Romero, A. H.; Shan, J.; Hilton, D. J.; Karaiskaj, D.

2017-10-01

We investigate the excitonic dephasing of transition metal dichalcogenides, namely MoS2, MoSe2 and WSe2 atomic monolayer thick and bulk crystals, in order to understand the factors that determine the optical coherence in these materials. Coherent nonlinear optical spectroscopy, temperature dependent absorption combined with theoretical calculations of the phonon spectra, reveal the important role electron-phonon interactions plat in dephasing process. The temperature dependence of the electronic band gap and the excitonic linewidth combined with 'ab initio' calculations of the phonon energies and the phonon density of state reveal strong interaction with the E‧ and E″ phonon modes.

The role of electron-phonon interactions on the coherence lifetime of monolayer transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Stevens, C. E.; Dey, P.; Paul, J.; Wang, Z.; Zhang, H.; Romero, A. H.; Shan, J.; Hilton, D. J.; Karaiskaj, D.

2017-06-01

We investigate the excitonic dephasing of transition metal dichalcogenides, namely MoS2, MoSe2 and WSe2 atomic monolayer thick and bulk crystals, in order to understand the factors that determine the optical coherence in these materials. Coherent nonlinear optical spectroscopy, temperature dependent absorption combined with theoretical calculations of the phonon spectra, reveal the important role electron-phonon interactions plat in dephasing process. The temperature dependence of the electronic band gap and the excitonic linewidth combined with ‘ab initio’ calculations of the phonon energies and the phonon density of state reveal strong interaction with the E’ and E” phonon modes.

Plate falling in a fluid: Regular and chaotic dynamics of finite-dimensional models

NASA Astrophysics Data System (ADS)

Kuznetsov, Sergey P.

2015-05-01

Results are reviewed concerning the planar problem of a plate falling in a resisting medium studied with models based on ordinary differential equations for a small number of dynamical variables. A unified model is introduced to conduct a comparative analysis of the dynamical behaviors of models of Kozlov, Tanabe-Kaneko, Belmonte-Eisenberg-Moses and Andersen-Pesavento-Wang using common dimensionless variables and parameters. It is shown that the overall structure of the parameter spaces for the different models manifests certain similarities caused by the same inherent symmetry and by the universal nature of the phenomena involved in nonlinear dynamics (fixed points, limit cycles, attractors, and bifurcations).

Development and Field Testing of the FootFall Planning System for the ATHLETE Robots

NASA Technical Reports Server (NTRS)

SunSpiral, Vytas; Wheeler, D. W.; Chavez-Clementa, Daniel; Mittman, David

2011-01-01

The FootFall Planning System is a ground-based planning and decision support system designed to facilitate the control of walking activities for the ATHLETE (All-Terrain Hex-Limbed Extra-Terrestrial Explorer) family of robots. ATHLETE was developed at NASA's Jet Propulsion Laboratory (JPL) and is a large six-legged robot designed to serve multiple roles during manned and unmanned missions to the Moon; its roles include transportation, construction and exploration. Over the four years from 2006 through 2010 the FootFall Planning System was developed and adapted to two generations of the ATHLETE robots and tested at two analog field sites (the Human Robotic Systems Project's Integrated Field Test at Moses Lake, Washington, June 2008, and the Desert Research and Technology Studies (D-RATS), held at Black Point Lava Flow in Arizona, September 2010). Having 42 degrees of kinematic freedom, standing to a maximum height of just over 4 meters, and having a payload capacity of 450 kg in Earth gravity, the current version of the ATHLETE robot is a uniquely complex system. A central challenge to this work was the compliance of the high-DOF (Degree Of Freedom) robot, especially the compliance of the wheels, which affected many aspects of statically-stable walking. This paper will review the history of the development of the FootFall system, sharing design decisions, field test experiences, and the lessons learned concerning compliance and self-awareness.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blobaum, K M

This month's issue has the following articles: (1) Fifty Years of Stellar Laser Research - Commentary by Edward I. Moses; (2) A Stellar Performance - By combining computational models with test shot data, scientists at the National Ignition Facility have demonstrated that the laser is spot-on for ignition; (3) Extracting More Power from the Wind - Researchers are investigating how atmospheric turbulence affects power production from wind turbines; (4) Date for a Heart Cell - Carbon-14 dating reveals that a significant number of heart muscle cells are regenerated over the course of our lives; and (5) Unique Marriage of Biologymore » and Semiconductors - A new device featuring a layer of fat surrounding a thin silicon wire takes advantage of the communication properties of both biomolecules and semiconductors.« less

MOSES: A Matlab-based open-source stochastic epidemic simulator.

PubMed

Varol, Huseyin Atakan

2016-08-01

This paper presents an open-source stochastic epidemic simulator. Discrete Time Markov Chain based simulator is implemented in Matlab. The simulator capable of simulating SEQIJR (susceptible, exposed, quarantined, infected, isolated and recovered) model can be reduced to simpler models by setting some of the parameters (transition probabilities) to zero. Similarly, it can be extended to more complicated models by editing the source code. It is designed to be used for testing different control algorithms to contain epidemics. The simulator is also designed to be compatible with a network based epidemic simulator and can be used in the network based scheme for the simulation of a node. Simulations show the capability of reproducing different epidemic model behaviors successfully in a computationally efficient manner.

The central masturbation fantasy in heterosexual males across the life cycle: masturbation fantasies across the normality-pathology spectrum.

PubMed

Colarusso, Calvin A

2012-10-01

Moses Laufer described the central masturbation fantasy as an essentially adolescent phenomenon that leads to the final sexual organization. In this paper the central masturbation fantasy, formulated during the preoedipal and oedipal years, consolidated in adolescence, and in a process of continuous evolution across the life cycle, is considered an essential concept for understanding sexuality in heterosexual males. Sex and aggression, as posited in Freud's dual theory of the drives, are core components of all masturbation fantasies, across the diagnostic spectrum, from the most normal/neurotic to the most criminally bizarre. Clinical examples illustrate both points. The tendency among clinicians, particularly clinical associates, to avoid analyzing all aspects of masturbation is discussed.

Optical turbulence forecast: ready for an operational application

NASA Astrophysics Data System (ADS)

Masciadri, E.; Lascaux, F.; Turchi, A.; Fini, L.

2017-04-01

One of the main goals of the feasibility study MOSE (MOdelling ESO Sites) is to evaluate the performances of a method conceived to forecast the optical turbulence (OT) above the European Southern Observatory (ESO) sites of the Very Large Telescope (VLT) and the European Extremely Large Telescope (E-ELT) in Chile. The method implied the use of a dedicated code conceived for the OT called ASTRO-MESO-NH. In this paper, we present results we obtained at conclusion of this project concerning the performances of this method in forecasting the most relevant parameters related to the OT (CN^2, seeing ɛ, isoplanatic angle θ0 and wavefront coherence time τ0). Numerical predictions related to a very rich statistical sample of nights uniformly distributed along a solar year and belonging to different years have been compared to observations, and different statistical operators have been analysed such as the classical bias, root-mean-squared error, σ and more sophisticated statistical operators derived by the contingency tables that are able to quantify the score of success of a predictive method such as the percentage of correct detection (PC) and the probability to detect a parameter within a specific range of values (POD). The main conclusions of the study tell us that the ASTRO-MESO-NH model provides performances that are already very good to definitely guarantee a not negligible positive impact on the service mode of top-class telescopes and ELTs. A demonstrator for an automatic and operational version of the ASTRO-MESO-NH model will be soon implemented on the sites of VLT and E-ELT.

Professional and Hospital DISCRIMINATION and the US Court of Appeals Fourth Circuit 1956–1967

PubMed Central

Reynolds, P. Preston

2004-01-01

A series of court cases litigated by the National Association for the Advancement of Colored People Legal Defense and Education Fund between 1956 and 1967 laid the foundation for elimination of overt discrimination in hospitals and professional associations. The landmark case, Simkins v Moses H. Cone Memorial Hospital (1963), challenged the use of public funds to expand segregated hospital care. The second case, Cypress v Newport News Hospital Association (1967), reaffirmed the federal government’s application of Medicare certification guidelines to force hospitals to open up patient admissions, education programs, and staff privileges to all citizens and physicians. Pursuit of a legal strategy against racist policies was an essential element in a national campaign to eliminate discrimination in health care delivery in the United States. PMID:15117685

Electron and thermal transport via variable range hopping in MoSe2 single crystals

NASA Astrophysics Data System (ADS)

Suri, Dhavala; Patel, R. S.

2017-06-01

Bulk single crystal molybdenum diselenide has been studied for its electronic and thermal transport properties. We perform resistivity measurements with current in-plane (CIP) and current perpendicular to plane (CPP) as a function of temperature. The CIP measurements exhibit metal to semiconductor transition at ≃31 K. In the semiconducting phase (T > 31 K), the transport is best explained by the variable range hopping (VRH) model. Large magnitude of resistivity in the CPP mode indicates strong structural anisotropy. The Seebeck coefficient as a function of temperature measured in the range of 90-300 K also agrees well with the VRH model. The room temperature Seebeck coefficient is found to be 139 μV/K. VRH fittings of the resistivity and the Seebeck coefficient data indicate high degree of localization.

Sediment texture and metal contamination in the Venice Lagoon (Italy): A snapshot before the installation of the MOSE system

NASA Astrophysics Data System (ADS)

Zonta, Roberto; Botter, Margherita; Cassin, Daniele; Bellucci, Luca Giorgio; Pini, Roberto; Dominik, Janusz

2018-05-01

Sediments of the Venice Lagoon down to 50 cm depth were investigated to assess sediment texture and metal contamination status, before the construction and activation of the MOSE system, which is intended to prevent the periodical flood events affecting the lagoon and the city of Venice. 380 cores were collected in shallow-water areas of the lagoon, and analysed along their vertical profile to determine grain-size distribution and concentrations of some major and trace elements (Al, As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn), total carbon and organic carbon. Radionuclide analyses (137Cs, 210Pb) were performed on 15 cores in an attempt to establish sediment chronology and determine radionuclide inventories in erosional and depositional areas. On the whole-lagoon scale, strong depletion of particles <31 μm in diameter (from medium silt to clay fractions) was observed in sediments down to 10 cm depth in comparison to deeper layers. This depletion characterised both erosional and depositional areas, and may be caused by increased water dynamics and resuspension of sediment due to anthropogenic activities. The apparent sediment accumulation rate determined with 210Pbxs in depositional areas was estimated at 0.2-0.4 cm y-1. In the majority of cores, 210Pbxs inventories were lower than expected from atmospheric fallout, suggesting its export along with fine particles. The different sediment characteristics in terms of grain-size distribution and organic carbon content observed in the upper layer with respect to the deeper ones reflect the modification of the sedimentary balance in recent years. The loss of fine particles, even from sediments in depositional areas of the northern part of the lagoon, may herald changes in local sediment texture leading to a further depletion of morphodiversity, which in turn may lead to the reduction or loss of important lagoon habitats. On the whole-lagoon scale, the prevalently lithogenic elements (Al, As, Cr, Fe, Mn, Ni) decreased towards the top of the cores, reflecting the depletion of fine particles in the upper sediment layer due to winnowing in non-confined lagoon areas. In contrast, partly anthropogenic elements (Cu, Hg, Pb, Zn) increased up to the subsurface sediment layers (5-10 and/or 10-20 cm) as an effect of increasing pollutant inputs until a certain time in the past. Enrichment Factors (EF) were calculated from 9 cores, comparing concentrations in the "pre-industrial" (>100 years ago) and recent (surface layer, 0-5 cm) sediments. The mostly lithogenic elements were not enriched (EF ˜ 1), whereas the partly anthropogenic elements showed slight (Cu and Pb, EF ˜ 1.2) to significant (Hg and Zn, EF ˜ 2) enrichment. The shallow waters on the landward side (particularly close to freshwater inputs), the area nearby the industrial district of Porto Marghera and a small zone adjacent to the city of Chioggia were identified as the main pollutant accumulation sites. Mercury was the only element potentially harmful for aquatic life. Its concentration in the biologically active surface sediment layer (0-5 cm) exceeded the NOAA Effects Range-Median (ERM) value in 27% of samples, corresponding to 20% of the shallow-water surface area. The collected data set represents a valuable reference for monitoring the impact of the construction and operation of the MOSE system on the sediment features of the Venice Lagoon.

The high resolution mapping of the Venice Lagoon tidal network

NASA Astrophysics Data System (ADS)

Madricardo, Fantina; Foglini, Federica; Kruss, Aleksandra; Bellafiore, Debora; Trincardi, Fabio

2017-04-01

One of the biggest challenges of the direct observation of the ocean is to achieve a high resolution mapping of its seafloor morphology and benthic habitats. So far, sonars have mapped just 0.05% of the ocean floor with less than ten-meter resolution. The recent efforts of the scientific community have been devoted towards the mapping of both Deep Ocean and very shallow coastal areas. Coastal and transitional environments in particular undergo strong morphological changes due to natural and anthropogenic pressure. Nowadays, only about 5% of the seafloor of these environments † have been mapped: the shallowness of these environments has prevented the use of underwater acoustics to reveal their morphological features. The recent technological development of multibeam echosounder systems, however, enables these instruments to achieve very high performances also in such shallow environments. In this work, we present results and case studies of an extensive multibeam survey carried out in the Lagoon of Venice in 2013. The Lagoon of Venice is the biggest lagoon in the Mediterranean Sea with a surface of about 550 km2 and with an average depth of about 1 m. In the last century, the morphological and ecological properties of the lagoon changed dramatically: the surface of the salt marshes was reduced by 60% and some parts of the lagoon are deepening with a net sediment flux exiting from the inlets. Moreover, major engineering interventions are currently ongoing at the inlets (MOSE project). These changes at the inlets could affect substantially the lagoon environment. To understand and monitor the future evolution of the Lagoon of Venice, ISMAR within the project RITMARE (a National Research Programme funded by the Italian Ministry of University and Research) carried out an extensive survey, involving a team of more than 25 scientists, to collect high resolution (0.5 m) bathymetry of key study areas such as the tidal inlets and channels. Following a broad multidisciplinary approach, bathymetric and backscatter intensity data are now employed for geomorphologic studies, habitat mapping and modelling of evolution trends of this highly dynamical and complex transitional environment.

Pleistocene glaciers, lakes, and floods in north-central Washington State

USGS Publications Warehouse

Waitt, Richard B.; Haugerud, Ralph A.; Kelsey, Harvey M.

2017-01-01

The Methow, Chelan, Wenatchee, and other terrane blocks accreted in late Mesozoic to Eocene times. Methow valley is excavated in an exotic terrane of folded Mesozoic sedimentary and volcanic rocks faulted between crystalline blocks. Repeated floods of Columbia River Basalt about 16 Ma drowned a backarc basin to the southeast. Cirques, aretes, and U-shaped hanging troughs brand the Methow, Skagit, and Chelan headwaters. The Late Wisconsin Cordilleran icesheet beveled the alpine topography and deposited drift. Cordilleran ice flowed into the heads of Methow tributaries and overflowed from Skagit tributaries to greatly augment Chelan trough's glacier. Joined Okanogan and Methow ice flowed down Columbia valley and up lower Chelan trough. This tongue met the icesheet tongue flowing southeast down Chelan valley. Successively lower ice-marginal channels and kame terraces show that the icesheet withered away largely by downwasting. Immense late Wisconsin floods from glacial Lake Missoula occasionally swept the Chelan-Vantage reach of Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP (by radiocarbon methods), raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As Cordilleran ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia. As advancing ice then blocked Moses Coulee, Grand Coulee to Quincy basin became the westmost floodway. From Quincy basin many Missoula floods backflowed 50 km upvalley past Wenatchee 18,000 to 15,500 years ago. Receding ice dammed glacial Lake Columbia centuries more--till it burst about 15,000 years ago. After Glacier Peak ashfall about 13,600 years ago, smaller great flood(s) swept down the Columbia from glacial Lake Kootenay in British Columbia. A cache of huge fluted Clovis points had been laid atop Pangborn bar (East Wenatchee) after the Glacier Peak ashfall. Clovis people came two and a half millennia after the last small Missoula flood, two millennia after the glacial Lake Columbia flood. This timing by radiocarbon methods is under review by newer exposure dating--10Be, 26Al, and 36Cl methods.

Variations of thermoelectric performance by electric fields in bilayer MX2 (M = W, Mo; X = S, Se).

PubMed

Wang, Rui-Ning; Dong, Guo-Yi; Wang, Shu-Fang; Fu, Guang-Sheng; Wang, Jiang-Long

2017-02-22

A gate electrode is usually used to controllably tune the carrier concentrations, further modulating the electrical conductivity and the Seebeck coefficient to obtain the optimum thermoelectric figure of merit (ZT) in two-dimensional materials. On the other hand, it is necessary to investigate how an electric field induced by a gate voltage affects the electronic structures, further determining the thermoelectric properties. Therefore, by using density functional calculations in combination with Boltzmann theory, the thermoelectric properties of bilayer MX 2 (M = W, Mo; X = S, Se) with or without a 1 V nm -1 perpendicular electric field are comparatively investigated. First of all, the variations of the electrical conductivity (σ), electron thermal conductivity and Seebeck coefficient (S) with the carrier concentration are studied. Due to the trade-off relationship between S and σ, there is an optimum concentration to obtain the maximum ZT, which increases with the temperature due to the enhancement of the Seebeck coefficient. Moreover, N-type bilayers have larger optimum ZTs than P-type bilayers. In addition, the electric field results in the increase of the Seebeck coefficient in low hole-doped MS 2 bilayers and high hole-doped MSe 2 bilayers, thus leading to similar variations in ZT. The optimum ZTs are reduced from 2.11 × 10 -2 , 3.19 × 10 -2 , 2.47 × 10 -2 , and 2.58 × 10 -2 to 1.57 × 10 -2 , 1.51 × 10 -2 , 2.08 × 10 -2 , and 1.43 × 10 -2 for the hole-doped MoS 2 , MoSe 2 , and WSe 2 bilayers, respectively. For N-type bilayers, the electric field shows a destructive effect, resulting in the obvious reduction of the Seebeck coefficient in the MSe 2 layers and the low electron-doped MS 2 bilayers. In electron-doped bilayers, the optimum ZTs will decrease from 3.03 × 10 -2 , 6.64 × 10 -2 , and 6.69 × 10 -2 to 2.81 × 10 -2 , 3.59 × 10 -2 , and 4.39 × 10 -2 for the MoS 2 , MoSe 2 , and WSe 2 bilayers, respectively.

Dealing with the forecast of the optical turbulence as a tool to support astronomy assisted by AO facilities

NASA Astrophysics Data System (ADS)

Masciadri, Elena; Lascaux, Franck; Fini, Luca

2015-04-01

In the context of the research activities related to the forecast of the optical turbulence and the atmospherical parameters being relevant for ground-based astronomy we focus here our attention on two specific topics: 1. pros and cons of different solutions to supply wind speed and direction stratification on the whole atmosphere all along a night to support AO facilities; 2. the necessity of instrumentation for optical turbulence monitoring (vertical profiles on the whole atmosphere) to be used operationally. In the last two decades the development and the use of different vertical profilers covering the whole atmosphere or part of it in application to the astronomy took place. Several instruments based on different principles (with associated pros and cons) have been applied in different contexts in astronomy with a main use in the site characterization and site selection. Time changed and the necessity of the astronomy supported by AO facilities is much more demanding with a diversification of applications. Recently, motivated by a precise necessity related to the identification of an absolute reference to carry out studies on optical turbulence forecasts (MOSE project), we carried out a verification of the reliability of a few instruments that lead us to put in evidence some limitations for a few of them. At the same time such a detailed analysis permitted us to clarify the nature of some astroclimatic parameters. The main conclusion at which we arrived is two-fold. From one side we could trace a list of warnings related to different uses of such instruments. On the other side we could identify open problems that indicate that there is still space for research in the field of turbulence monitoring in application to the astronomy. Some suggestions are proposed.

The past, present, and future of soils and human health studies

NASA Astrophysics Data System (ADS)

Brevik, E. C.; Sauer, T. J.

2015-01-01

The idea that human health is tied to the soil is not a new one. As far back as circa 1400 BC the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. In 400 BC the Greek philosopher Hippocrates provided a list of things that should be considered in a proper medical evaluation, including the properties of the local ground. By the late 1700s and early 1800s, American farmers had recognized that soil properties had some connection to human health. In the modern world, we recognize that soils have a distinct influence on human health. We recognize that soils influence (1) food availability and quality (food security), (2) human contact with various chemicals, and (3) human contact with various pathogens. Soils and human health studies include investigations into nutrient supply through the food chain and routes of exposure to chemicals and pathogens. However, making strong, scientific connections between soils and human health can be difficult. There are multiple variables to consider in the soil environment, meaning traditional scientific studies that seek to isolate and manipulate a single variable often do not provide meaningful data. The complete study of soils and human health also involves many different specialties such as soil scientists, toxicologists, medical professionals, anthropologists, etc. These groups do not traditionally work together on research projects, and do not always effectively communicate with one another. Climate change and how it will affect the soil environment/ecosystem going into the future is another variable affecting the relationship between soils and health. Future successes in soils and human health research will require effectively addressing difficult issues such as these.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kochat, Vidya; Apte, Amey; Hachtel, Jordan A.

Alloying in 2D results in the development of new, diverse, and versatile systems with prospects in bandgap engineering, catalysis, and energy storage. Tailoring structural phase transitions using alloying is a novel idea with implications in designing all 2D device architecture as the structural phases in 2D materials such as transition metal dichalcogenides are correlated with electronic phases. In this paper, this study develops a new growth strategy employing chemical vapor deposition to grow monolayer 2D alloys of Re-doped MoSe 2 with show composition tunable structural phase variations. The compositions where the phase transition is observed agree well with the theoreticalmore » predictions for these 2D systems. Finally, it is also shown that in addition to the predicted new electronic phases, these systems also provide opportunities to study novel phenomena such as magnetism which broadens the range of their applications.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolic, R J

This month's issue has the following articles: (1) Dawn of a New Era of Scientific Discovery - Commentary by Edward I. Moses; (2) At the Frontiers of Fundamental Science Research - Collaborators from national laboratories, universities, and international organizations are using the National Ignition Facility to probe key fundamental science questions; (3) Livermore Responds to Crisis in Post-Earthquake Japan - More than 70 Laboratory scientists provided round-the-clock expertise in radionuclide analysis and atmospheric dispersion modeling as part of the nation's support to Japan following the March 2011 earthquake and nuclear accident; (4) A Comprehensive Resource for Modeling, Simulation, and Experimentsmore » - A new Web-based resource called MIDAS is a central repository for material properties, experimental data, and computer models; and (5) Finding Data Needles in Gigabit Haystacks - Livermore computer scientists have developed a novel computer architecture based on 'persistent' memory to ease data-intensive computations.« less

Theoretical ultra-fast spectroscopy in transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Molina-Sanchez, Alejandro; Sangalli, Davide; Marini, Andrea; Wirtz, Ludger

Semiconducting 2D-materials like the transition metal dichalcogenides (TMDs) MoS2, MoSe2, WS2, WSe2 are promising alternatives to graphene for designing novel opto-electronic devices. The strong spin-orbit interaction along with the breaking of inversion symmetry in single-layer TMDs allow using the valley-index as a new quantum number. The practical use of valley physics depends on the lifetimes of valley-polarized excitons which are affected by scattering at phonons, impurities and by carrier-carrier interactions. The carrier dynamics can be monitored using ultra-fast spectroscopies such as pump-probe experiments. The carrier dynamics is simulated using non-equilibrium Green's function theory in an ab-initio framework. We include carrier relaxation through electron-phonon interaction. We obtain the transient absorption spectra of single-layer TMD and compare our simulations with recent pump-probe experiments

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

PubMed

Wang, Qing Hua; Kalantar-Zadeh, Kourosh; Kis, Andras; Coleman, Jonathan N; Strano, Michael S

2012-11-01

The remarkable properties of graphene have renewed interest in inorganic, two-dimensional materials with unique electronic and optical attributes. Transition metal dichalcogenides (TMDCs) are layered materials with strong in-plane bonding and weak out-of-plane interactions enabling exfoliation into two-dimensional layers of single unit cell thickness. Although TMDCs have been studied for decades, recent advances in nanoscale materials characterization and device fabrication have opened up new opportunities for two-dimensional layers of thin TMDCs in nanoelectronics and optoelectronics. TMDCs such as MoS(2), MoSe(2), WS(2) and WSe(2) have sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. We review the historical development of TMDCs, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.

Capsule physics comparison of National Ignition Facility implosion designs using plastic, high density carbon, and beryllium ablators

NASA Astrophysics Data System (ADS)

Clark, D. S.; Kritcher, A. L.; Yi, S. A.; Zylstra, A. B.; Haan, S. W.; Weber, C. R.

2018-03-01

Indirect drive implosion experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] have now tested three different ablator materials: glow discharge polymer plastic, high density carbon, and beryllium. How do these different ablators compare in current and proposed implosion experiments on NIF? What are the relative advantages and disadvantages of each? This paper compares these different ablator options in capsule-only simulations of current NIF experiments and potential future designs. The simulations compare the impact of the capsule fill tube, support tent, and interface surface roughness for each case, as well as all perturbations in combination. According to the simulations, each ablator is impacted by the various perturbation sources differently, and each material poses unique challenges in the pursuit of ignition on NIF.

Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures.

PubMed

Garcia, Jose H; Cummings, Aron W; Roche, Stephan

2017-08-09

We report on a theoretical study of the spin Hall Effect (SHE) and weak antilocalization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS 2 system is found to maximize spin proximity effects compared to graphene on MoS 2 , WSe 2 , or MoSe 2 with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency. For further experimental studies of graphene/TMDC heterostructures, our findings provide guidelines for reaching the upper limit of spin current formation and for fully harvesting the potential of two-dimensional materials for spintronic applications.

The Past, Present, and Future of Soils and Human Health Studies

NASA Astrophysics Data System (ADS)

Brevik, E. C.; Sauer, T. J.

2012-04-01

The idea that human health is tied to the soil is not a new one. As far back as approximately 1400 B.C. the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. While exploring Canaan, Moses charged the men he sent to evaluate the fertility of the soil. In 400 B.C. the Greek philosopher Hippocrates provided a list of things that should be considered in a proper medical evaluation, including the ground. By the late 1700 and early 1800s, American farmers had recognized that soil properties had some connection to human health. In "Letters from an American Farmer", published in 1792, J. Hector St. John De Crèvecoeur stated "Men are like plants; the goodness and flavor of the fruit proceeds from the peculiar soil and exposition in which they grow". And in "Larding the Lean Earth", published in 2002, S. Stoll noted that North American farmers in the early 1800s recognized a link between an enduring agriculture and an enduring society, leading them to become concerned about the fertility of their soils and to seek ways of improving the soil in order to insure a healthy society. Continuing into the first half of the 20th Century, a 1940 publication by the International Harvester Company noted that poor soils lead to "stoop-shouldered, poverty-stricken people." Then, in 1947, Sir Albert Howard published his landmark work "The Soil and Health: A Study of Organic Agriculture", a work that took a critical look at modern production agriculture and at the link between soil fertility and health. Despite these various lines of evidence of some earlier level of understanding that healthy soils are required for healthy people, the scientific study of the relationship between soils and human health is a fairly new undertaking. In his 1997 work "Soil and Human Health: A Review", M.A. Oliver states "… there is a dearth of quantitative information on the relations between elements in the soil and human health;…there is much speculation and anecdotal evidence." So, the scientific study of soils and human health is a recent undertaking, but the idea that healthy soils are required for healthy people is not a particularly new one. In the modern world, we recognize that soils have a distinct influence on human health. We recognize that soils influence 1) food availability and quality (food security), 2) human contact with various chemicals, and 3) human contact with various pathogens. Soils and human health studies include investigations into nutrient supply through the food web and routes of exposure to chemicals and pathogens. However, making strong, scientific connections between soils and human health can be difficult. There are multiple variables to consider in the soil environment, meaning traditional scientific studies that seek to isolate and manipulate a single variable often do not provide meaningful data. The complete study of soils and human health also involves many different specialties such as soil scientists, toxicologists, medical professionals, anthropologists, etc. These groups do not traditionally work together on research projects, and do not always effectively communicate with one another. Climate change and how it will affect the soil environment/ecosystem going into the future is another variable we need to get a better understanding of. Future successes in soils and human health research will require effectively addressing difficult issues such as these.

Development of Raman Spectroscopy as a Clinical Diagnostic Tool

NASA Astrophysics Data System (ADS)

Borel, Santa

Raman spectroscopy is the collection of inelastically scattered light in which the spectra contain biochemical information of the probed cells or tissue. This work presents both targeted and untargeted ways that the technique can be exploited in biological samples. First, surface enhanced Raman scattering (SERS) gold nanoparticles conjugated to targeting antibodies were shown to be successful for multiplexed detection of overexpressed surface antigens in lung cancer cell lines. Further work will need to optimize the conjugation technique to preserve the strong binding affinity of the antibodies. Second, untargeted Raman microspectroscopy combined with multivariate statistical analysis was able to successfully differentiate mouse ovarian surface epithelial (MOSE) cells and spontaneously transformed ovarian surface epithelial (STOSE) cells with high accuracy. The differences between the two groups were associated with increased nucleic acid content in the STOSE cells. This shows potential for single cell detection of ovarian cancer.

Laser irradiance scaling in polar direct drive implosions on the National Ignition Facility

DOE PAGES

Murphy, T. J.; Krasheninnikova, N. S.; Kyrala, G. A.; ...

2015-09-17

Polar-direct-drive experiments conducted at the National Ignition Facility [E. I. Moses, Fusion Sci. Technol. 54, 361 (2008)] performed at laser irradiance between 1 and 2×10 15 W/cm 2 exhibit increased hard x-ray emission, decreased neutron yield, and reduced areal density as the irradiance is increased. Experimental x-ray images at the higher irradiances show x-ray emission at the equator, as well as degraded symmetry, that is not predicted in hydrodynamic simulations using flux-limited energy transport, but that appear when non-local electron transport together with a model to account for cross beam energy transfer (CBET) is utilized. The reduction in laser powermore » for equatorial beams required in the simulations to reproduce the effects of CBET on the observed symmetry also reproduces the yield degradation consistent with experimental data.« less

n-MoSe2 photoelectrochemical halogen storage cell

NASA Astrophysics Data System (ADS)

Ang, P. G. P.; Sammells, A. F.

1982-01-01

In the study reported here, single-crystal n-MoSe2 photoanodes are investigated in a variety of halogen redox couples. The photoanode is prepared by allowing the silver epoxy cement to come into contact with the front surface of the crystal before being insulated from the redox electrolyte with paraffin wax. This photoanode is evaluated in bromine redox electrolytes in various pH ranges. In 1M HBr + 1M Br2 (pH, approximately zero), the initial open-circuit potential of the MoSe2 versus a platinum reference electrode in the same electrolyte is -130 mV in the dark and -480 mV under 200 mW/sq cm xenon illumination. It is noted that improved performance could be achieved with such crystals by subjecting them to an anodic polarization of around 1 volt from the initial resting potential, a current of about 5 mA/sq cm flowing in the dark.

Band-bending induced by charged defects and edges of atomically thin transition metal dichalcogenide films

NASA Astrophysics Data System (ADS)

Le Quang, T.; Nogajewski, K.; Potemski, M.; Dau, M. T.; Jamet, M.; Mallet, P.; Veuillen, J.-Y.

2018-07-01

We report scanning tunneling microscopy/spectroscopy (STM/STS) investigations of the band-bending in the vicinity of charged point defects and edges of monolayer MoSe2 and mono- and trilayer WSe2 films deposited on graphitized silicon carbide substrates. By tracing the spatial evolution of the structures of the STS spectra, we evaluate the magnitude and the extent of the band-bending to be equal to few hundreds milielectronvolts and several nanometres, respectively. With the aid of a simple electrostatic model, we show that the spatial variation of the Coulomb potential close to the film edges can be well reproduced by taking into account the metallic screening by graphene. Additionally, the analysis of our data for trilayer WSe2 provides reasonable estimations of its dielectric constant () and of the magnitude of the charge trapped at the defect site (Q  =  +e).

Photonic Architectures for Equilibrium High-Temperature Bose-Einstein Condensation in Dichalcogenide Monolayers

PubMed Central

Jiang, Jian-Hua; John, Sajeev

2014-01-01

Semiconductor-microcavity polaritons are composite quasiparticles of excitons and photons, emerging in the strong coupling regime. As quantum superpositions of matter and light, polaritons have much stronger interparticle interactions compared with photons, enabling rapid equilibration and Bose-Einstein condensation (BEC). Current realizations based on 1D photonic structures, such as Fabry-Pérot microcavities, have limited light-trapping ability resulting in picosecond polariton lifetime. We demonstrate, theoretically, above-room-temperature (up to 590 K) BEC of long-lived polaritons in MoSe2 monolayers sandwiched by simple TiO2 based 3D photonic band gap (PBG) materials. The 3D PBG induces very strong coupling of 40 meV (Rabi splitting of 62 meV) for as few as three dichalcogenide monolayers. Strong light-trapping in the 3D PBG enables the long-lived polariton superfluid to be robust against fabrication-induced disorder and exciton line-broadening. PMID:25503586

Water-level altitudes 2012 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2011 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2012-01-01

Compaction of subsurface sediments (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973 (or later) and ending in December 2011, cumulative compaction data collected from the 13 extensometers ranged from 0.102 ft at the Texas City–Moses Lake site to 3.621 ft at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas on the basis of the rate of compaction measured at a nearby extensometer.

Controllable growth of layered selenide and telluride heterostructures and superlattices using molecular beam epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vishwanath, Suresh; Liu, Xinyu; Rouvimov, Sergei

2016-01-06

Layered materials are an actively pursued area of research for realizing highly scaled technologies involving both traditional device structures as well as new physics. Lately, non-equilibrium growth of 2D materials using molecular beam epitaxy (MBE) is gathering traction in the scientific community and here we aim to highlight one of its strengths, growth of abrupt heterostructures, and superlattices (SLs). In this work we present several of the firsts: first growth of MoTe 2 by MBE, MoSe 2 on Bi 2Se 3 SLs, transition metal dichalcogenide (TMD) SLs, and lateral junction between a quintuple atomic layer of Bi 2Te 3 andmore » a triple atomic layer of MoTe 2. In conclusion, reflected high electron energy diffraction oscillations presented during the growth of TMD SLs strengthen our claim that ultrathin heterostructures with monolayer layer control is within reach.« less

Janus Monolayer Transition-Metal Dichalcogenides.

PubMed

Zhang, Jing; Jia, Shuai; Kholmanov, Iskandar; Dong, Liang; Er, Dequan; Chen, Weibing; Guo, Hua; Jin, Zehua; Shenoy, Vivek B; Shi, Li; Lou, Jun

2017-08-22

The crystal configuration of sandwiched S-Mo-Se structure (Janus SMoSe) at the monolayer limit has been synthesized and carefully characterized in this work. By controlled sulfurization of monolayer MoSe 2 , the top layer of selenium atoms is substituted by sulfur atoms, while the bottom selenium layer remains intact. The structure of this material is systematically investigated by Raman, photoluminescence, transmission electron microscopy, and X-ray photoelectron spectroscopy and confirmed by time-of-flight secondary ion mass spectrometry. Density functional theory (DFT) calculations are performed to better understand the Raman vibration modes and electronic structures of the Janus SMoSe monolayer, which are found to correlate well with corresponding experimental results. Finally, high basal plane hydrogen evolution reaction activity is discovered for the Janus monolayer, and DFT calculation implies that the activity originates from the synergistic effect of the intrinsic defects and structural strain inherent in the Janus structure.

Maimonides’ Appreciation for Medicine

PubMed Central

Gesundheit, Benjamin

2011-01-01

Moses Maimonides, the illustrious medieval rabbi and philosopher, dedicated the last decade of his life primarily to medicine. His strong interest in medicine was an integral component of his religious-philosophical teachings and world view. In this paper various sources from his rabbinic writings are presented that explain Maimonides’ motivation regarding and deep appreciation for medicine: (A) The physician fulfills the basic biblical obligation to return lost objects to their owner, for with his knowledge and experience the physician can restore good health to his sick fellow human being; (B) medicine provides a unique opportunity to practice imitatio dei, as it reflects the religious duty to maintain a healthy life-style; (C) as an important natural science, medicine offers tools to recognize, love, and fear God. These three aspects address man’s relationship and obligation towards his fellow-man, himself and God. Biographical insights supported by additional sources from Maimonides’ writings are discussed. PMID:23908790

Janus Monolayer Transition-Metal Dichalcogenides

DOE PAGES

Zhang, Jing; Jia, Shuai; Kholmanov, Iskandar; ...

2017-08-03

In this work, the crystal configuration of sandwiched S–Mo–Se structure (Janus SMoSe) at the monolayer limit has been synthesized and carefully characterized. By controlled sulfurization of monolayer MoSe 2, the top layer of selenium atoms is substituted by sulfur atoms, while the bottom selenium layer remains intact. Furthermore, the structure of this material is systematically investigated by Raman, photoluminescence, transmission electron microscopy, and X-ray photoelectron spectroscopy and confirmed by time-of-flight secondary ion mass spectrometry. Density functional theory (DFT) calculations are performed to better understand the Raman vibration modes and electronic structures of the Janus SMoSe monolayer, which are found tomore » correlate well with corresponding experimental results. Finally, high basal plane hydrogen evolution reaction activity is discovered for the Janus monolayer, and DFT calculation implies that the activity originates from the synergistic effect of the intrinsic defects and structural strain inherent in the Janus structure.« less

A scholarly intermediary between the Ottoman Empire and Renaissance Europe.

PubMed

Morrison, Robert

2014-03-01

This essay studies Moses Galeano, a Jewish scholar with ties to Crete and the Ottoman Sultan's court, who traveled to the Veneto around 1500. After describing Galeano's intellectual milieu, it focuses, first, on circumstantial evidence that he transmitted information central to the rise of Renaissance astronomy. Galeano knew of theories that strongly resemble portions of astronomy texts written by Giovanni Battista Amico and Girolamo Fracastoro at Padua a few decades later. He also knew about theories pioneered by the Damascene Ibn al-Shāţir (d. 1375) that strongly resemble portions of Copernicus's work. Next, the article turns to concrete evidence showing that Galeano was part of a network of Jewish scholars who did have contact with Christian scholars in Europe. The essay concludes that, while it is impossible to prove that Galeano had direct contact with Copernicus, he most likely had contact with some European astronomer(s) in the Veneto.

The Great Copernican Cliché

NASA Astrophysics Data System (ADS)

Danielson, D. R.

2000-12-01

Almost all the school science texts say what Britain's Astronomer Royal also recently reasserted: ``Copernicus dethroned the Earth from the privileged position that Ptolemy's cosmology accorded it." This non-scientific equation of geocentrism with anthropocentrism does an injustice to medieval cosmology, obscures some genuinely anthropocentric aspects of Copernican theory, and impedes a critical evaluation of what modern cosmology does and does not actually impy concerning the ``place" of humankind in the cosmos. By means of a cheerful but serious guided tour of Aristotelian cosmological physics and of Copernican enthusiasm at humankind's *exaltation* to the dance of the stars--with brief visits to Chalcidius, Martianus Capella, Moses Maimonides, and the poet Dante, as well as to Copernicus himself, Digges, Galileo, Kepler, le Bouvier de Fontenelle, and Huygens--this lecture will dismantle the Great Copernican Cliché and show how much richer our account of Copernicanism can be without it.

Interfaces of high-efficiency kesterite Cu2ZnSnS(e)4 thin film solar cells

NASA Astrophysics Data System (ADS)

Gao, Shoushuai; Jiang, Zhenwu; Wu, Li; Ao, Jianping; Zeng, Yu; Sun, Yun; Zhang, Yi

2018-01-01

Cu2ZnSnS(e)4 (CZTS(e)) solar cells have attracted much attention due to the elemental abundance and the non-toxicity. However, the record efficiency of 12.6% for Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is much lower than that of Cu(In,Ga)Se2 (CIGS) solar cells. One crucial reason is the recombination at interfaces. In recent years, large amount investigations have been done to analyze the interfacial problems and improve the interfacial properties via a variety of methods. This paper gives a review of progresses on interfaces of CZTS(e) solar cells, including: (1) the band alignment optimization at buffer/CZTS(e) interface, (2) tailoring the thickness of MoS(e)2 interfacial layers between CZTS(e) absorber and Mo back contact, (3) the passivation of rear interface, (4) the passivation of front interface, and (5) the etching of secondary phases.

KSC-2011-4243

NASA Image and Video Library

2011-06-01

CAPE CANAVERAL, Fla. -- In the Press Site auditorium at NASA's Kennedy Space Center in Florida, NASA managers brief media after space shuttle Endeavour's successful landing and conclusion of its STS-134 and final mission. From left are, Associate Administrator for Space Operations Bill Gerstenmaier, Space Shuttle Program Launch Integration Manager Mike Moses; and Shuttle Launch Director Mike Leinbach. Endeavour and its crew delivered the Alpha Magnetic Spectrometer-2 (AMS) and the Express Logistics Carrier-3 (ELC-3) to the International Space Station. AMS will help researchers understand the origin of the universe and search for evidence of dark matter, strange matter and antimatter from the station. ELC-3 carried spare parts that will sustain station operations once the shuttles are retired from service. STS-134 was the 25th and final flight for Endeavour, which spent 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles. Photo credit: NASA/Kim Shiflett

Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides

DOE PAGES

Selig, Malte; Berghäuser, Gunnar; Raja, Archana; ...

2016-11-07

Atomically thin transition metal dichalcogenides are direct-gap semiconductors with strong light–matter and Coulomb interactions. The latter accounts for tightly bound excitons, which dominate their optical properties. Besides the optically accessible bright excitons, these systems exhibit a variety of dark excitonic states. They are not visible in the optical spectra, but can strongly influence the coherence lifetime and the linewidth of the emission from bright exciton states. We investigate the microscopic origin of the excitonic coherence lifetime in two representative materials (WS 2 and MoSe 2) through a study combining microscopic theory with spectroscopic measurements. We also show that the excitonicmore » coherence lifetime is determined by phonon-induced intravalley scattering and intervalley scattering into dark excitonic states. Particularly, we identify exciton relaxation processes involving phonon emission into lower-lying dark states that are operative at all temperatures, in WS 2.« less

Electronic and optical properties of MoSe2 monolayer in the presence of Nb impurity: A first principle study

NASA Astrophysics Data System (ADS)

Kumar, Sanjeev; Sharma, Munish; Ahluwalia, P. K.

2018-04-01

The study of electronic and optical properties of Molybdenum diselenide monolayer (1H-MoSe2) in the presence of Niobium impurity (Nb), has been calculated and compared with available experimental and other calculated results in the literature. The electronic and optical properties of this system are investigated in the two cases.i) when MoS2 monolayer is doped suitably with Nb ii) when Nb is added (intercalated in the interstitial sites) suitably. The presence of even 2.08% Nb as an impurity reflects strong bonding with the host and results in semiconducting to metallic transition, which is also reflected in the overlap of σ valence band and п plasmon band in EELS. Thus, Molybdenum diselenide monolayer in the presence of Nb impurity appears to be a potential a candidate for applications in electrical and optical devices.

Diagnosing and controlling mix in National Ignition Facility implosion experiments a)

NASA Astrophysics Data System (ADS)

Hammel, B. A.; Scott, H. A.; Regan, S. P.; Cerjan, C.; Clark, D. S.; Edwards, M. J.; Epstein, R.; Glenzer, S. H.; Haan, S. W.; Izumi, N.; Koch, J. A.; Kyrala, G. A.; Landen, O. L.; Langer, S. H.; Peterson, K.; Smalyuk, V. A.; Suter, L. J.; Wilson, D. C.

2011-05-01

High mode number instability growth of "isolated defects" on the surfaces of National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] capsules can be large enough for the perturbation to penetrate the imploding shell, and produce a jet of ablator material that enters the hot-spot. Since internal regions of the CH ablator are doped with Ge, mixing of this material into the hot-spot results in a clear signature of Ge K-shell emission. Evidence of jets entering the hot-spot has been recorded in x-ray images and spectra, consistent with simulation predictions [Hammel et al., High Energy Density Phys. 6, 171 (2010)]. Ignition targets have been designed to minimize instability growth, and capsule fabrication improvements are underway to reduce "isolated defects." An experimental strategy has been developed where the final requirements for ignition targets can be adjusted through direct measurements of mix and experimental tuning.

Structure, tribological and electrochemical properties of low friction TiAlSiCN/MoSeC coatings

NASA Astrophysics Data System (ADS)

Bondarev, A. V.; Kiryukhantsev-Korneev, Ph. V.; Sheveyko, A. N.; Shtansky, D. V.

2015-02-01

The present paper is focused on the development of hard tribological coatings with low friction coefficient (CoF) in different environments (humid air, distilled water) and at elevated temperatures. TiAlSiCN/MoSeC coatings were deposited by magnetron sputtering of four-segment targets consisting of quarter circle TiAlSiCN segments, obtained by self-propagating high-temperature synthesis, and one or two cold pressed segments made of MoSe2 and C powders in a ratio 1:1 wt%. The structure and phase composition of coatings were investigated by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery. The tribological properties of coatings were investigated first at room temperature against Al2O3 and WC-Co balls, after which studied in distilled water and during continuous heating in air in the temperature range of 25-400 °C against Al2O3 counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H2SO4 solution. The obtained results show that the coating hardness depends on the amount of MoSeC additives and decreased from 40 to 28 (one MoSeC segment) and 12 GPa (two MoSeC segments). Doping with MoSeC resulted in a significant reduction of CoF values measured in humid air (RH 60 ± 5%) from 0.8-0.9 to 0.05 and an increase of wear resistance by one or two orders of magnitude depending on counterpart material. This was attributed to the presence of MoSe2 and free carbon-based phases in the tribological contact. The TiAlSiCN/MoSeC coating with a maximal amount of MoSeC also demonstrated superior tribological characteristics in distilled water (CoF ∼ 0.1) and at moderate temperatures up to 300 °C (CoF < 0.1). The electrochemical tests showed that, in general, doping with MoSeC did not negatively affect the coating electrochemical behavior. On the contrary, the MoSeC phase demonstrated small positive effect on the anti-corrosive properties of TiAlSiCN coatings under small polarizations.

2D-photochemical modeling of Saturn’s stratosphere: hydrocarbon and water distributions

NASA Astrophysics Data System (ADS)

Hue, Vincent; Cavalié, Thibault; Hersant, Franck; Dobrijevic, Michel; Greathouse, Thomas; Lellouch, Emmanuel; Hartogh, Paul; Cassidy, Timothy; Spiga, Aymeric; Guerlet, Sandrine; Sylvestre, Melody

2014-11-01

Saturn’s axial tilt of 27° produces seasons in a similar way as on Earth. The seasonal forcing over Saturn’s 30 years period influences the production/loss of the major atmospheric absorbers and coolants through photochemistry, and influences therefore Saturn’s stratospheric temperatures. We have developed a 2D time-dependent photochemical model of Saturn’s atmosphere [Hue et al., in prep.], coupled to a radiative-climate model [Greathouse et al., 2008] to study seasonal effects on its atmospheric composition. Cassini spacecraft has revealed that the distribution of hydrocarbons in Saturn’s stratosphere [Guerlet et al., 2009] differs from pure photochemical predictions, i.e. without meridional transport [Moses et al., 2005]. Differences between the observed distribution of hydrocarbons and 2D-photochemical predictions are likely to be an indicator of dynamical forcing.Disentangling the origin of water in the stratosphere of this planet has been a long-term issue. Due to Saturn’s cold tropopause trap, which acts as a transport barrier, the water vapor observed by the Infrared Space Observatory (ISO) [Feuchtgruber et al., 1997] has an external origin. Three external sources have been identified: (i) permanent flux from interplanetary dust particles, (ii) local sources form planetary environments (rings, satellites), (iii) large cometary impacts, similar to Shoemaker-Levy 9 on Jupiter. Previous observations of Saturn with Herschel’s Hsso program [Hartogh et al., 2009] led to the detection of a water torus around Saturn [Hartogh et al., 2011], fed by Enceladus’ geysers. A substantial fraction of this torus is predicted to be a local source of water for Saturn’s and its satellites, as it will spread in this system [Cassidy et al., 2010]. Using the new 2D-photochemical model, we test here the validity of Enceladus’ torus as the source of Saturn’s stratospheric water.References : Hue et al., in prep. Greathouse et al., 2008. AGU Fall Meeting(Abstract P21B06). Guerlet et al., 2009. Icarus, 203, 214-232. Moses et al., 2005. JGR 110. Feuchtgruber et al., 1997. 389, 159-162. Hartogh et al., 2009. PSS 57, 1596-1606 Hartogh et al., 2011. A&A, 532, L2. Cassidy et al., 2010. Icarus, 209, 696-703

Hydrated Spinel Websterite Xenoliths From Moses Rock Diatreme, Navajo Volcanic Field: Metasomatism in the Mantle Wedge of the Colorado Plateau Above the De-watering Farallon Plate

NASA Astrophysics Data System (ADS)

Schulze, D. J.; Chow, R.; Helmstaedt, H. H.

2016-12-01

Expansion and density decrease in ultramafic rocks in the mantle wedge above the subducted and dewatering Farallon Plate in the Cenozoic may have been the driving force behind uplift of the Colorado Plateau. Here we document the effects of such hydration on spinel websterites that resulted in rocks dominated by pargasitic amphibole, Mg-chlorite and Cr-magnetite/chromite. Xenoliths of spinel websterite from the Moses Rock diatreme in the Navajo Volcanic Field on the Colorado Plateau have granoblastic to mosaic porphyroclastic texture. Porphyroclasts (up to 2 cm across) of lamellar intergrowths of clinopyroxene and orthopyroxene are set in a granular matrix of sub-equal amounts of the two pyroxenes. Both pyroxenes are magnesian and aluminous, with Mg/(Mg+Fe) in the range 0.89 to 0.93 and Al2O3 contents of approximately 4.0 to 9.5 wt%. Many samples contain aluminous spinel with Al/(Al+Cr) = 0.82 to 0.94. The effects of hydration on these samples exist as partial to complete replacement of the pyroxenes by amphibole (tremolite/edenite/pargasite/magnesio-hornblende), pseudomorphing original pyroxene textures, and replacement of primary spinel by Cr-rich magnetite or chromite with Al/(Al+Cr) = 0.07 to 0.35 intergrown with, and surrounded by, clinochlore. Unusual minerals associated with replacement of primary spinel include one example with corundum + zoisite, one with secondary garnet (molar Ca:Mg:Fe = 20:40:40) and two samples with aluminous talc (5 to 7 wt% Al2O3). By analogy with Alpine peridotites and mantle xenolith suites from basalt occurrences, the spinel websterites probably existed as veins and lenses in spinel peridotite of the shallow upper mantle beneath the Colorado Plateau prior to hydration. De-watering of the subducted Farallon Plate in Cenozoic time was likely the source of water-rich fluids that caused the hydration at fairly shallow depths (within amphibole stability), as suggested for hydration of spinel peridotite xenoliths from the Buell Park and Green Knobs diatremes further south. The volume increase and density decrease accompanying hydration of the peridotites and pyroxenites were important factors in the uplift of the Colorado Plateau.

The Challenge of High-resolution Mapping of Very Shallow Coastal Areas: Case Study of the Lagoon of Venice, Italy

NASA Astrophysics Data System (ADS)

Madricardo, F.; Foglini, F.; Kruss, A.; Bajo, M.; Campiani, E.; Ferrarin, C.; Fogarin, S.; Grande, V.; Janowski, L.; Keppel, E.; Leidi, E.; Lorenzetti, G.; Maicu, F.; Maselli, V.; Montereale Gavazzi, G.; Pellegrini, C.; Petrizzo, A.; Prampolini, M.; Remia, A.; Rizzetto, F.; Rovere, M.; Sarretta, A.; Sigovini, M.; Toso, C.; Zaggia, L.; Trincardi, F.

2017-12-01

Very shallow coastal environments are often highly urbanized with half of the world's population and 13 of the largest mega-cities located close to the coast. These environments undergo rapid morphological changes due to natural and anthropogenic pressure that will likely be enhanced in the near future by mean sea-level rise. Therefore, there is a strong need for high resolution seafloor mapping to monitor and protect shallow coastal areas. To date, only about 5% of their seafloor has been mapped: their shallowness has prevented so far the use of underwater acoustics to reveal their morphological features; their turbidity often hindered the efficient use of LIDAR technology, particularly in lagoons and estuaries. The recent technological development of multibeam echosounder systems, however, enables these instruments to achieve very high performances also in such shallow environments. In this work, we present the results of an extensive multibeam survey carried out in the Lagoon of Venice (Italy) in 2013. The Lagoon of Venice is the biggest lagoon in the Mediterranean Sea (surface area of about 550 km2, average depth of about 1 m) and it is a UNESCO World Cultural and Natural Heritage site together with the historical city of Venice which is currently endangered by relative sea-level rise. Major engineering works are ongoing at the lagoon inlets (MOSE project) to protect Venice from flood events. In the last century, the morphology and ecology of the lagoon changed dramatically: the extent of the salt marshes was reduced by 60% and some parts of the lagoon deepened by more than 1 m with a net sediment flux exiting from the inlets. To understand and monitor the future evolution of the Lagoon of Venice in view of the inlet modifications and mean sea-level rise, CNR-ISMAR within the project RITMARE (a National Research Programme funded by the Italian Ministry of University and Research) carried out an extensive survey, involving a team of more than 25 scientists, to collect high resolution (0.5 m) bathymetry of key study areas such as the tidal inlets and channels. Bathymetric and backscatter intensity data are now employed for geomorphologic studies, habitat mapping and modelling representing a paradigm of a broad multidisciplinary approach to monitor shallow coastal systems.

Probing the role of interlayer coupling and coulomb interactions on electronic structure in few-layer MoSe₂ nanostructures.

PubMed

Bradley, Aaron J; Ugeda, Miguel M; da Jornada, Felipe H; Qiu, Diana Y; Ruan, Wei; Zhang, Yi; Wickenburg, Sebastian; Riss, Alexander; Lu, Jiong; Mo, Sung-Kwan; Hussain, Zahid; Shen, Zhi-Xun; Louie, Steven G; Crommie, Michael F

2015-04-08

Despite the weak nature of interlayer forces in transition metal dichalcogenide (TMD) materials, their properties are highly dependent on the number of layers in the few-layer two-dimensional (2D) limit. Here, we present a combined scanning tunneling microscopy/spectroscopy and GW theoretical study of the electronic structure of high quality single- and few-layer MoSe2 grown on bilayer graphene. We find that the electronic (quasiparticle) bandgap, a fundamental parameter for transport and optical phenomena, decreases by nearly one electronvolt when going from one layer to three due to interlayer coupling and screening effects. Our results paint a clear picture of the evolution of the electronic wave function hybridization in the valleys of both the valence and conduction bands as the number of layers is changed. This demonstrates the importance of layer number and electron-electron interactions on van der Waals heterostructures and helps to clarify how their electronic properties might be tuned in future 2D nanodevices.

Mo1-xWxSe2-Based Schottky Junction Photovoltaic Cells.

PubMed

Yi, Sum-Gyun; Kim, Sung Hyun; Park, Sungjin; Oh, Donggun; Choi, Hwan Young; Lee, Nara; Choi, Young Jai; Yoo, Kyung-Hwa

2016-12-14

We developed Schottky junction photovoltaic cells based on multilayer Mo 1-x W x Se 2 with x = 0, 0.5, and 1. To generate built-in potentials, Pd and Al were used as the source and drain electrodes in a lateral structure, and Pd and graphene were used as the bottom and top electrodes in a vertical structure. These devices exhibited gate-tunable diode-like current rectification and photovoltaic responses. Mo 0.5 W 0.5 Se 2 Schottky diodes with Pd and Al electrodes exhibited higher photovoltaic efficiency than MoSe 2 and WSe 2 devices with Pd and Al electrodes, likely because of the greater adjusted band alignment in Mo 0.5 W 0.5 Se 2 devices. Furthermore, we showed that Mo 0.5 W 0.5 Se 2 -based vertical Schottky diodes yield a power conversion efficiency of ∼16% under 532 nm light and ∼13% under a standard air mass 1.5 spectrum, demonstrating their remarkable potential for photovoltaic applications.

Pronounced Photovoltaic Response from Multilayered Transition-Metal Dichalcogenides PN-Junctions.

PubMed

Memaran, Shahriar; Pradhan, Nihar R; Lu, Zhengguang; Rhodes, Daniel; Ludwig, Jonathan; Zhou, Qiong; Ogunsolu, Omotola; Ajayan, Pulickel M; Smirnov, Dmitry; Fernández-Domínguez, Antonio I; García-Vidal, Francisco J; Balicas, Luis

2015-11-11

Transition metal dichalcogenides (TMDs) are layered semiconductors with indirect band gaps comparable to Si. These compounds can be grown in large area, while their gap(s) can be tuned by changing their chemical composition or by applying a gate voltage. The experimental evidence collected so far points toward a strong interaction with light, which contrasts with the small photovoltaic efficiencies η ≤ 1% extracted from bulk crystals or exfoliated monolayers. Here, we evaluate the potential of these compounds by studying the photovoltaic response of electrostatically generated PN-junctions composed of approximately 10 atomic layers of MoSe2 stacked onto the dielectric h-BN. In addition to ideal diode-like response, we find that these junctions can yield, under AM-1.5 illumination, photovoltaic efficiencies η exceeding 14%, with fill factors of ~70%. Given the available strategies for increasing η such as gap tuning, improving the quality of the electrical contacts, or the fabrication of tandem cells, our study suggests a remarkable potential for photovoltaic applications based on TMDs.

Absolute Summ

NASA Astrophysics Data System (ADS)

Phillips, Alfred, Jr.

Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

Extraordinary attributes of 2-dimensional MoS2 nanosheets

NASA Astrophysics Data System (ADS)

Rao, C. N. R.; Maitra, Urmimala; Waghmare, Umesh V.

2014-08-01

The discovery of the amazing properties of graphene has stimulated exploration of single- and few-layer structures of layered inorganic materials. Of all the inorganic 2D nanosheet structures, those of MoS2 have attracted great attention because of their novel properties such as the presence of a direct bandgap, good field-effect transistor characteristics, large spin-orbit splitting, intense photoluminescence, catalytic properties, magnetism, superconductivity, ferroelectricity and several other properties with potential applications in electronics, optoelectronics, energy devices and spintronics. MoS2 nanosheets have been used in lithium batteries, supercapacitors and to generate hydrogen. Highlights of the impressive properties of MoS2 nanosheets, along with their structural and spectroscopic features are presented in this Letter. MoS2 typifies the family of metal dichalcogenides such as MoSe2 and WS2 and there is much to be done on nanosheets of these materials. Linus Pauling would have been pleased to see how molybdenite whose structure he studied in 1923 has become so important today.

Classification of E-Nose Aroma Data of Four Fruit Types by ABC-Based Neural Network

PubMed Central

Adak, M. Fatih; Yumusak, Nejat

2016-01-01

Electronic nose technology is used in many areas, and frequently in the beverage industry for classification and quality-control purposes. In this study, four different aroma data (strawberry, lemon, cherry, and melon) were obtained using a MOSES II electronic nose for the purpose of fruit classification. To improve the performance of the classification, the training phase of the neural network with two hidden layers was optimized using artificial bee colony algorithm (ABC), which is known to be successful in exploration. Test data were given to two different neural networks, each of which were trained separately with backpropagation (BP) and ABC, and average test performances were measured as 60% for the artificial neural network trained with BP and 76.39% for the artificial neural network trained with ABC. Training and test phases were repeated 30 times to obtain these average performance measurements. This level of performance shows that the artificial neural network trained with ABC is successful in classifying aroma data. PMID:26927124

KSC-2011-3419

NASA Image and Video Library

2011-05-09

CAPE CANAVERAL, Fla. -- In the Press Site auditorium at NASA's Kennedy Space Center in Florida, Space Shuttle Program Launch Integration Manager Mike Moses briefs media about the launch status of space shuttle Endeavour's STS-134 mission and announces a new launch date. Technicians replaced and tested the aft load control assembly-2 (ALCA-2) and wiring located in Endeavour's aft avionics bay 5. ALCA-2 distributes power to nine shuttle systems and is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail April 29 during the first launch attempt. Launch now is scheduled for May 16 at 8:56 a.m. EDT. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

KSC-2011-3308

NASA Image and Video Library

2011-04-29

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, Public Affairs Officer George Diller, Kennedy Director Bob Cabana, Space Shuttle Program Launch Integration Manager Mike Moses and Shuttle Launch Director Mike Leinbach participate in a news conference following the April 29 scrubbed launch attempt of space shuttle Endeavour. During the STS-134 countdown, fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) failed. Technicians later discovered that the Load Control Assembly-2 (LCA-2), which distributes power to nine shuttle systems, was the cause of the failure reading. The LCA-2 located in Endeavour's aft section will be replaced and systems will be retested before the launch is rescheduled. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. The mission also will be the final spaceflight for Endeavour. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

Mapping Thermal Expansion Coefficients in Freestanding 2D Materials at the Nanometer Scale

NASA Astrophysics Data System (ADS)

Hu, Xuan; Yasaei, Poya; Jokisaari, Jacob; Öǧüt, Serdar; Salehi-Khojin, Amin; Klie, Robert F.

2018-02-01

Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, and photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation and thermal mismatch can be a problem in designing electronic devices based on two-dimensional materials. Quantifying the thermal expansion coefficient of 2D materials requires temperature measurements at nanometer scale. Here, we introduce a novel nanometer-scale thermometry approach to measure temperature and quantify the thermal expansion coefficients in 2D materials based on scanning transmission electron microscopy combined with electron energy-loss spectroscopy to determine the energy shift of the plasmon resonance peak of 2D materials as a function of sample temperature. By combining these measurements with first-principles modeling, the thermal expansion coefficients (TECs) of single-layer and freestanding graphene and bulk, as well as monolayer MoS2 , MoSe2 , WS2 , or WSe2 , are directly determined and mapped.

Estimation of the contribution of exports to the provincial economy: an analysis based on China's multi-regional input-output tables.

PubMed

Wu, Sanmang; Li, Shantong; Lei, Yalin

2016-01-01

This paper developed an estimation model for the contribution of exports to a country's regional economy based on the Chenery-Moses model and conducted an empirical analysis using China's multi-regional input-output tables for 1997, 2002, and 2007. The results indicated that China's national exports make significantly different contributions to the provincial economy in various regions, with the greatest contribution being observed in the eastern region and the smallest in the central region. The provinces are also subjected to significantly different export spillover effects. The boosting effect for the eastern provinces is primarily generated from local exports, whereas the western provinces primarily benefit from the export spillover effect from the eastern provinces. The eastern provinces, such as Guangdong, Zhejiang, Jiangsu, and Shanghai, are the primary sources of export spillover effects, and Guangdong is the largest source of export spillover effects for almost all of the provinces in China.

Copper indium gallium selenide (CIGS) photovoltaic devices made using multistep selenization of nanocrystal films.

PubMed

Harvey, Taylor B; Mori, Isao; Stolle, C Jackson; Bogart, Timothy D; Ostrowski, David P; Glaz, Micah S; Du, Jiang; Pernik, Douglas R; Akhavan, Vahid A; Kesrouani, Hady; Vanden Bout, David A; Korgel, Brian A

2013-09-25

The power conversion efficiency of photovoltaic devices made with ink-deposited Cu(InxGa1-x)Se2 (CIGS) nanocrystal layers can be enhanced by sintering the nanocrystals with a high temperature selenization process. This process, however, can be challenging to control. Here, we report that ink deposition followed by annealing under inert gas and then selenization can provide better control over CIGS nanocrystal sintering and yield generally improved device efficiency. Annealing under argon at 525 °C removes organic ligands and diffuses sodium from the underlying soda lime glass into the Mo back contact to improve the rate and quality of nanocrystal sintering during selenization at 500 °C. Shorter selenization time alleviates excessive MoSe2 formation at the Mo back contact that leads to film delamination, which in turn enables multiple cycles of nanocrystal deposition and selenization to create thicker, more uniform absorber films. Devices with power conversion efficiency greater than 7% are fabricated using the multiple step nanocrystal deposition and sintering process.

Mapping Thermal Expansion Coefficients in Freestanding 2D Materials at the Nanometer Scale.

PubMed

Hu, Xuan; Yasaei, Poya; Jokisaari, Jacob; Öğüt, Serdar; Salehi-Khojin, Amin; Klie, Robert F

2018-02-02

Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, and photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation and thermal mismatch can be a problem in designing electronic devices based on two-dimensional materials. Quantifying the thermal expansion coefficient of 2D materials requires temperature measurements at nanometer scale. Here, we introduce a novel nanometer-scale thermometry approach to measure temperature and quantify the thermal expansion coefficients in 2D materials based on scanning transmission electron microscopy combined with electron energy-loss spectroscopy to determine the energy shift of the plasmon resonance peak of 2D materials as a function of sample temperature. By combining these measurements with first-principles modeling, the thermal expansion coefficients (TECs) of single-layer and freestanding graphene and bulk, as well as monolayer MoS_{2}, MoSe_{2}, WS_{2}, or WSe_{2}, are directly determined and mapped.

Association of immature stages of some caddisfly species from northwestern Argentina with description of a new species of Helicopsyche (Trichoptera: Helicopsychidae).

PubMed

Martín, Paola A Rueda; Miranda, Águeda Verónica Isa

2015-04-24

The adult, larva, and pupa of Helicopsyche obscura sp. nov. from northwestern Argentina are described and illustrated. Descriptions and illustrations of adults and associated pupae and larvae of Helicopsyche turbida Navás and Leptonema boliviense boliviense Mosely are included. The associations of immature stages were made using the metamorphotype method. Helicopsyche turbida is newly recorded from Tucumán province. The adult males of H. obscura sp. nov. and H. turbida have similar structure in the genital segments, however, the most clear differences are in the general color and size of the adult, and in the color, size, and morphology of the metanota in the larval stages as well as the shapes of mandibles, hook plates, and terminal segments of the pupal stages. The larva and pupa of L. boliviense boliviense are compared with those of L. columbianum and other previously described species, providing differences in color, chaetotaxy, and morphology.

Re Doping in 2D Transition Metal Dichalcogenides as a New Route to Tailor Structural Phases and Induced Magnetism

DOE PAGES

Kochat, Vidya; Apte, Amey; Hachtel, Jordan A.; ...

2017-10-09

Alloying in 2D results in the development of new, diverse, and versatile systems with prospects in bandgap engineering, catalysis, and energy storage. Tailoring structural phase transitions using alloying is a novel idea with implications in designing all 2D device architecture as the structural phases in 2D materials such as transition metal dichalcogenides are correlated with electronic phases. In this paper, this study develops a new growth strategy employing chemical vapor deposition to grow monolayer 2D alloys of Re-doped MoSe 2 with show composition tunable structural phase variations. The compositions where the phase transition is observed agree well with the theoreticalmore » predictions for these 2D systems. Finally, it is also shown that in addition to the predicted new electronic phases, these systems also provide opportunities to study novel phenomena such as magnetism which broadens the range of their applications.« less

Ethanol catalytic optical driven deposition for 1D and 2D materials with ultra-low power threshold of 0 dBm

NASA Astrophysics Data System (ADS)

Wang, Hao; Chen, Bohua; Xiao, Xu; Guo, Chaoshi; Zhang, Xiaoyan; Wang, Jun; Jiang, Meng; Wu, Kan; Chen, Jianping

2018-01-01

We have demonstrated a generalized optical driven deposition method, ethanol catalytic deposition (ECD) method, which is widely applicable to the deposition of a broad range of one-dimensional (1D) and two-dimensional (2D) materials with common deposition parameters. Using ECD method, deposition of 1D material carbon nanotubes and 2D materials MoS2, MoSe2, WS2 and WSe2 on tapered fiber has been demonstrated with the threshold power as low as 0 dBm. To our knowledge, this is the lowest threshold power ever reported in optical driven deposition, noting that the conventional optical driven deposition has a threshold typically near 15 dBm. It means ECD method can significantly reduce the power requirement and simplify the setup of the optical driven deposition as well as its wide applicability to different materials, which benefits the research on optical nonlinearity and ultrafast photonics of 1D and 2D materials.

Exploring the limits of case-to-capsule ratio, pulse length, and picket energy for symmetric hohlraum drive on the National Ignition Facility Laser

NASA Astrophysics Data System (ADS)

Callahan, D. A.; Hurricane, O. A.; Ralph, J. E.; Thomas, C. A.; Baker, K. L.; Benedetti, L. R.; Berzak Hopkins, L. F.; Casey, D. T.; Chapman, T.; Czajka, C. E.; Dewald, E. L.; Divol, L.; Döppner, T.; Hinkel, D. E.; Hohenberger, M.; Jarrott, L. C.; Khan, S. F.; Kritcher, A. L.; Landen, O. L.; LePape, S.; MacLaren, S. A.; Masse, L. P.; Meezan, N. B.; Pak, A. E.; Salmonson, J. D.; Woods, D. T.; Izumi, N.; Ma, T.; Mariscal, D. A.; Nagel, S. R.; Kline, J. L.; Kyrala, G. A.; Loomis, E. N.; Yi, S. A.; Zylstra, A. B.; Batha, S. H.

2018-05-01

We present a data-based model for low mode asymmetry in low gas-fill hohlraum experiments on the National Ignition Facility {NIF [Moses et al., Fusion Sci. Technol. 69, 1 (2016)]} laser. This model is based on the hypothesis that the asymmetry in these low fill hohlraums is dominated by the hydrodynamics of the expanding, low density, high-Z (gold or uranium) "bubble," which occurs where the intense outer cone laser beams hit the high-Z hohlraum wall. We developed a simple model which states that the implosion symmetry becomes more oblate as the high-Z bubble size becomes large compared to the hohlraum radius or the capsule size becomes large compared to the hohlraum radius. This simple model captures the trends that we see in data that span much of the parameter space of interest for NIF ignition experiments. We are now using this model as a constraint on new designs for experiments on the NIF.

Comparison of fishes in nearshore areas of the St. Lawrence River, New York over 35 years

USGS Publications Warehouse

Carlson, Douglas M.; McKenna, James E.

2014-01-01

Fishes of the nearshore waters of the St. Lawrence River provide forage for valuable sport fisheries and are important biological indicators of condition and change. This fish community differs slightly among various reaches of the St. Lawrence River from New York to Quebec (Carlson et al. 2006, Eckert and Hanlon 1977, Kapuscinski 2011, LaViolette et al. 2003, Mandrak et al. 2006, McKenna et al. 2005). Nearshore habitat has been described by McKenna et al. (2012), and others have suggested that there were changes over the last few decades (Clapsadl 1993, Kapuscinski and Farrell 2013). More definitive work needs to be completed on submerged aquatic vegetation habitats. In this paper, changes in the nearshore fish species composition for the New York reach from Cape Vincent to Moses-Saunders Dam are examined through comparison of results from 2009-2010 (McKenna et al. 2012) and 1976 surveys (Eckert and Hanlon 1977).

A disorder-enhanced quasi-one-dimensional superconductor

PubMed Central

Petrović, A. P.; Ansermet, D.; Chernyshov, D.; Hoesch, M.; Salloum, D.; Gougeon, P.; Potel, M.; Boeri, L.; Panagopoulos, C.

2016-01-01

A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2−δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials. PMID:27448209

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, D. S.; Milovich, J. L.; Hinkel, D. E.

Recent experimental results using the “high foot” pulse shape for inertial confinement fusion ignition experiments on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] have shown encouraging progress compared to earlier “low foot” experiments. These results strongly suggest that controlling ablation front instability growth can significantly improve implosion performance even in the presence of persistent, large, low-mode distortions. Simultaneously, hydrodynamic growth radiography experiments have confirmed that ablation front instability growth is being modeled fairly well in NIF experiments. It is timely then to combine these two results and ask how current ignition pulse shapes couldmore » be modified to improve one-dimensional implosion performance while maintaining the stability properties demonstrated with the high foot. This paper presents such a survey of pulse shapes intermediate between the low and high foot extremes in search of an intermediate foot optimum. Of the design space surveyed, it is found that a higher picket version of the low foot pulse shape shows the most promise for improved compression without loss of stability.« less

Band-edges and band-gap in few-layered transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Bhunia, Hrishikesh; Pal, Amlan J.

2018-05-01

We have considered liquid-exfoliated transition metal dichalcogenides (WS2, WSe2, MoS2, and MoSe2) and studied their band-edges and band-gap through scanning tunneling spectroscopy (STS) and density of states. A monolayer, bilayer (2L), and trilayer (3L) of each of the layered materials were characterized to derive the energies. Upon an increase in the number of layers, both the band-edges were found to shift towards the Fermi energy. The results from the exfoliated nanosheets have been compared with reported STS studies of MoS2 and WSe2 formed through chemical vapor deposition or molecular beam epitaxy methods; an uncontrolled lattice strain existed in such 2L and 3L nanoflakes due to mismatch in stacking-patterns between the monolayers affecting their energies. In the present work, the layers formed through the liquid-exfoliation process retained their interlayer coupling or stacking-sequence prevalent to the bulk and hence allowed determination of band-energies in these strain-free two-dimensional materials.

A redundant resource: a pre-planned casualty clearing station for a FIFA 2010 Stadium in Durban.

PubMed

Hardcastle, Timothy C; Samlal, Sanjay; Naidoo, Rajen; Hendrikse, Steven; Gloster, Alex; Ramlal, Melvin; Ngema, Sibongiseni; Rowe, Michael

2012-10-01

This report details the background, planning, and establishment of a mass-casualty management area for the Durban Moses Mabhida Stadium at the Natal Mounted Rifles base, by the Department of Health and the eThekwini Fire and Rescue Service, for the Fédération Internationale de Football Association (FIFA) 2010 Soccer World Cup. The report discusses the use of the site during the seven matches played at that stadium, and details the aspects of mass-gathering major incident site planning for football (soccer). The area also was used as a treatment area for other single patient incidents outside of the stadium, but within the exclusion perimeter, and the 22 patients treated by the Casualty Clearing Station (CCS) team are described and briefly discussed. A site-specific patient presentation rate of 0.48 per 10,000 and transport-to-hospital rate (TTHR) of 0.09/10,000 are reported. Lessons learned and implications for future event planning are discussed in the light of the existing literature.

[The son of man. Freud's Oedipus myth].

PubMed

Bollack, J

1993-07-01

In formulating his psychology of the unconscious, Freud makes constant reference to Sophocles' version of the Oedipus myth. The author provides detailed proof of the fundamental differences between the two versions, demonstrating that Freud's interpretation does violence to the source. Bollack marshals impressive evidence to substantiate his contention that from the early letters to Fliess all the way up to Moses and Monotheism Freud's sole concern was to point up the ubiquitous power of the unconscious (incestual desire, patricide) within the "holy" (nuclear) family, whereas Sophocles was preoccupied with an entirely different problem. In Bollack's view, Oedipus rex is the drama of the self-destruction of a royal family, a drama in which incest and murder have no very essential significance. Freud, by contrast, set out to de-mystify the fate that dogs the royal family from one generation to the next and to naturalise it into a form of unconscious behaviour--a tendency which Bollack sees as deriving from the tradition of the "drama of destiny", a genre prevalent in the 19th century.

Classification of E-Nose Aroma Data of Four Fruit Types by ABC-Based Neural Network.

PubMed

Adak, M Fatih; Yumusak, Nejat

2016-02-27

Electronic nose technology is used in many areas, and frequently in the beverage industry for classification and quality-control purposes. In this study, four different aroma data (strawberry, lemon, cherry, and melon) were obtained using a MOSES II electronic nose for the purpose of fruit classification. To improve the performance of the classification, the training phase of the neural network with two hidden layers was optimized using artificial bee colony algorithm (ABC), which is known to be successful in exploration. Test data were given to two different neural networks, each of which were trained separately with backpropagation (BP) and ABC, and average test performances were measured as 60% for the artificial neural network trained with BP and 76.39% for the artificial neural network trained with ABC. Training and test phases were repeated 30 times to obtain these average performance measurements. This level of performance shows that the artificial neural network trained with ABC is successful in classifying aroma data.

A disorder-enhanced quasi-one-dimensional superconductor.

PubMed

Petrović, A P; Ansermet, D; Chernyshov, D; Hoesch, M; Salloum, D; Gougeon, P; Potel, M; Boeri, L; Panagopoulos, C

2016-07-22

A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2-δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials.

Low-frequency Raman fingerprints of two-dimensional metal dichalcogenide layer stacking configurations

DOE PAGES

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan; ...

2015-05-12

In this study, stacked monolayers of two-dimensional (2D) materials present a new class of hybrid materials with tunable optoelectronic properties determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) and electron energy loss spectroscopy (EELS) can be used to determine the exact atomic registration between different layers, in few-layer 2D stacks, however fast optical characterization techniques are essential for rapid development of the field. Here, using two- and three-layer MoSe 2 and WSe 2 crystals synthesized by chemical vapor deposition we show that the generally unexplored low frequency (LF) Raman modes (< 50more » cm -1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations. Ab initio calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan

In this study, stacked monolayers of two-dimensional (2D) materials present a new class of hybrid materials with tunable optoelectronic properties determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) and electron energy loss spectroscopy (EELS) can be used to determine the exact atomic registration between different layers, in few-layer 2D stacks, however fast optical characterization techniques are essential for rapid development of the field. Here, using two- and three-layer MoSe 2 and WSe 2 crystals synthesized by chemical vapor deposition we show that the generally unexplored low frequency (LF) Raman modes (< 50more » cm -1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations. Ab initio calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries.« less

KSC-2011-1517

NASA Image and Video Library

2011-02-18

CAPE CANAVERAL, Fla. -- At NASA's Kennedy Space Center in Florida, NASA Public Affairs Officer Michael Curie, left, Associate Administrator for Space Operations Bill Gerstenmaier, Space Shuttle Program Launch Integration Manager Mike Moses and Shuttle Launch Director Mike Leinbach talk to media following a Flight Readiness Review that gave a unanimous "go" to launch space shuttle Discovery on the STS-133 mission to the International Space Station. This will be the second launch attempt for Discovery, following a scrub in November 2010 due to a hydrogen gas leak at the ground umbilical carrier plate (GUCP) as well as modifications to the external fuel tank's intertank support beams, called stringers. Scheduled to lift off Feb. 24 at 4:50 p.m. EST, Discovery and its six-member crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. For more information on the STS-133 mission, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/. Photo credit: NASA/Kim Shiflett

Cumulative trauma, PTSD and dissociation among Ethiopian refugees in Israel.

PubMed

Finklestein, Michal; Solomon, Zahava

2009-01-01

The aim of this study was to examine the exposure of Ethiopian refugees to pre-, peri- and post-migration stressful events and their implications for both posttraumatic stress disorder (PTSD) and dissociation. A random sample (N = 478) of three groups of refugees took part in the research ("Moses" immigrants, 1984, n = 165; "Solomon" immigrants, 1991, n = 169; "Family Reunification" immigrants, 1995, n = 144). Exposure to stressful events and posttraumatic symptoms were assessed via the Harvard Trauma Questionnaire (HTQ). Post-migration difficulties were assessed via the Post Migration Living Difficulties (PMLD) scale. Dissociation was evaluated using the Dissociation Experience Scale (DES). Significant differences were found among the groups in the rates of PTSD (27%, 15%, and 26%, respectively), but no differences were found in dissociation. A significant relationship was found between PTSD symptoms and cumulative trauma among the three groups, but no such relationship was found between dissociation and cumulative trauma. The differences among the groups were discussed in light of the unique characteristics of cumulative trauma, PTSD and dissociation among Ethiopian refugees.

Eight years of groundwater monitoring at the building site of the MOSE system for the safeguard of Venice

NASA Astrophysics Data System (ADS)

Casasso, Alessandro; Sethi, Rajandrea; Di Molfetta, Antonio

2015-04-01

The survival of Venice is threatened by the continuous increase of frequency and intensity of tidal floods. To prevent these events, a safeguarding system known as MOSE is under construction at the inlets of the Lagoon of Venice. Four arrays of mobile barriers will be lifted in the case of exceptionally high tides (>1.10 m) to insulate the Lagoon. The prefabrication of the mobile barriers required a large construction area close to the final installation sites. Given the lack of space in the inlets of Lido and Chioggia, two basins of the future navigation locks were used for this purpose, and a system of water pumps and wells was therefore installed in each site to ensure the accessibility and safety of the construction areas. The impact of dewatering on the aquifers on the mainland in Punta Sabbioni (inlet of Lido) was monitored by means of continuous hydraulic head measurements in a network 25 piezometers, 11 screened in the phreatic aquifer and 14 in the shallowest confined aquifer. These aquifers are separated by a 5 m thick clayey aquiclude, and a 30 m thick impervious layer isolates them from the underlying confined aquifers, which were therefore not monitored. Each monitoring well was equipped with an automatic water pressure transducer and the hourly recorded hydraulic heads were compensated with the barometric pressure. The time series were compared with the natural driving forces (tides, rainfall, evapotranspiration) and the anthropogenic impact sources (dewatering pumping, slurry walls, land reclamation channels). The dynamics of seawater intrusion were also studied through monthly measurements of the vertical profiles of the electrical conductivity (EC) of groundwater. The monitoring activity was successful in assessing the impacts of the construction works. A drawdown was observed in the confined aquifer due to the dewatering pumping, with a maximum displacement of some 5 m on the mainland and an extension of some 1000 m from the dewatered basin. By contrast, no impact was observed in the phreatic aquifer, proving that the combined insulation effect of the slurry wall and the aquiclude was successful in avoiding the depletion of this water body. At the end of the dewatering pumping, the confined aquifer fully recovered, returning to its pristine conditions in a few months. The EC measurements revealed that a de-salinization trend occurred in a portion of the phreatic aquifer, due to the presence of the slurry wall. The results of the monitoring programme brought some useful insights, that could also be applied to other groundwater monitoring programs in large construction works. The ante operam monitoring phase lasted for some 15 months, thus allowing a thorough understanding of the groundwater dynamics over more than an hydrological yearly cycle. A large area was covered to identify the impacted areas with a high level of precision. The short-term groundwater level dynamics have been revealed thanks to continuous measurements in all the monitored wells. EC measurements proved to be a low-cost and valuable tool to study the cycles and the long-term trends of seawater intrusion. References: Attanayake PM, Waterman MK (2006), Identifying environmental impacts of underground construction. Hydrogeology Journal, 14: 1160-1170. DOI: 10.1007/s10040-006-0037-0 Bras RL, Harleman DRF, Rinaldo A, Rizzoli P (2001) Rescuing Venice from a watery grave. Science 291:2315-2316 Casasso A, Di Molfetta A, Sethi R (2014) Groundwater monitoring at a building site of the tidal protection system "MOSE" in the Lagoon of Venice, Italy. Environmental Earth Sciences, in press. DOI: 10.1007/s12665-014-3588-8 Rinaldo A, Nicotina L, Celegon EA, Beraldin F, Botter G, Carniello L, Cecconi G, Defina A, Settin T, Uccelli A, D'Alpaos L, Marani M (2008) Sea level rise, hydrologic runoff, and the flooding of Venice. Water Resources Research 44, W12434. DOI:10.1029/2008wr007195 Strozzi T, Teatini P, Tosi L (2009) TerraSAR-X reveals the impact of the mobile barrier works on Venice coastland stability. Remote Sensing of Environment 113:2682-2688. DOI:10.1016/j.rse.2009.08.001

Explicit and Implicit Verbal Response Inhibition in Preschool-Age Children Who Stutter.

PubMed

Anderson, Julie D; Wagovich, Stacy A

2017-04-14

The purpose of this study was to examine (a) explicit and implicit verbal response inhibition in preschool children who do stutter (CWS) and do not stutter (CWNS) and (b) the relationship between response inhibition and language skills. Participants were 41 CWS and 41 CWNS between the ages of 3;1 and 6;1 (years;months). Explicit verbal response inhibition was measured using a computerized version of the grass-snow task (Carlson & Moses, 2001), and implicit verbal response inhibition was measured using the baa-meow task. Main dependent variables were reaction time and accuracy. The CWS were significantly less accurate than the CWNS on the implicit task, but not the explicit task. The CWS also exhibited slower reaction times than the CWNS on both tasks. Between-group differences in performance could not be attributed to working memory demands. Overall, children's performance on the inhibition tasks corresponded with parents' perceptions of their children's inhibition skills in daily life. CWS are less effective and efficient than CWNS in suppressing a dominant response while executing a conflicting response in the verbal domain.

Semantic transference for enriching multilingual biomedical knowledge resources.

PubMed

Pérez, María; Berlanga, Rafael

2015-12-01

Biomedical knowledge resources (KRs) are mainly expressed in English, and many applications using them suffer from the scarcity of knowledge in non-English languages. The goal of the present work is to take maximum profit from existing multilingual biomedical KRs lexicons to enrich their non-English counterparts. We propose to combine different automatic methods to generate pair-wise language alignments. More specifically, we use two well-known translation methods (GIZA++ and Moses), and we propose a new ad hoc method specially devised for multilingual KRs. Then, resulting alignments are used to transfer semantics between KRs across their languages. Transference quality is ensured by checking the semantic coherence of the generated alignments. Experiments have been carried out over the Spanish, French and German UMLS Metathesaurus counterparts. As a result, the enriched Spanish KR can grow up to 1,514,217 concepts (originally 286,659), the French KR up to 1,104,968 concepts (originally 83,119), and the German KR up to 1,136,020 concepts (originally 86,842). Copyright © 2015 Elsevier Inc. All rights reserved.

Water-level altitudes 2013 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973--2012 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2013-01-01

Compaction of subsurface sediments (mostly in the clay and silt layers) of the Chicot and Evangeline aquifers was recorded continuously by 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2012, cumulative measured compaction by 12 of the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.632 ft at the Addicks extensometer (data were used from only one of two extensometers at one site). The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas based on the rate of compaction measured at a nearby extensometer.

Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, D. S.; Weber, C. R.; Smalyuk, V. A.

2016-07-15

Current indirect drive implosion experiments on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are believed to be strongly impacted by long wavelength perturbations driven by asymmetries in the hohlraum x-ray flux. To address this perturbation source, active efforts are underway to develop modified hohlraum designs with reduced asymmetry imprint. An alternative strategy, however, is to modify the capsule design to be more resilient to a given amount of hohlraum asymmetry. In particular, the capsule may be deliberately misshaped, or “shimmed,” so as to counteract the expected asymmetries from the hohlraum. Here, the efficacy ofmore » capsule shimming to correct the asymmetries in two recent NIF implosion experiments is assessed using two-dimensional radiation hydrodynamics simulations. Despite the highly time-dependent character of the asymmetries and the high convergence ratios of these implosions, simulations suggest that shims could be highly effective at counteracting current asymmetries and result in factors of a few enhancements in neutron yields. For higher compression designs, the yield improvement could be even greater.« less

Constraints on crustal hydration below the Colorado plateau from Vp measurements on crustal xenoliths

NASA Astrophysics Data System (ADS)

Padovani, Elaine R.; Hall, Jeremy; Simmons, Gene

1982-04-01

Seismic velocities have been measured as a function of confining pressure to 8 kbar for crustal xenoliths from the Moses Rock Dike and Mule Ear Diatreme, two kimberlite pipes on the Colorado Plateau. Rock types measured include rhyolite, granite, diorite, metasedimentary schists and gneisses, mafic amphibolites and granulites. Many of our samples have been hydrothermally altered to greenschist facies mineral assemblages during transport to the earth's surface. The velocity of compressional waves measured on altered amphibolites and granulites are too low by 0.1-0.3 km/s for such rock types to be characteristic of deep crustal levels. A direct correlation exists between progressive alteration and the presence of microcracks extending into the xenoliths from the kimberlitic host rock. Velocities of pristine samples are compatible with existing velocity profiles for the Colorado Plateau and we conclude that the crust at depths greater than 15 km has probably not undergone a greenschist facies metamorphic event. The xenolith suite reflects a crustal profile similar to that exposed in the Ivrea-Verbano and Strona-Ceneri zones in northern Italy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weilacher, F.; Radha, P. B., E-mail: rbah@lle.rochester.edu; Collins, T. J. B.

Ongoing polar-direct-drive (PDD) implosions on the National Ignition Facility (NIF) [J. D. Lindl and E. I. Moses, Phys. Plasmas 18, 050901 (2011)] use existing NIF hardware, including indirect-drive phase plates. This limits the performance achievable in these implosions. Spot shapes are identified that significantly improve the uniformity of PDD NIF implosions; outer surface deviation is reduced by a factor of 7 at the end of the laser pulse and hot-spot distortion is reduced by a factor of 2 when the shell has converged by a factor of ∼10. As a result, the neutron yield increases by approximately a factor ofmore » 2. This set of laser spot shapes is a combination of circular and elliptical spots, along with elliptical spot shapes modulated by an additional higher-intensity ellipse offset from the center of the beam. This combination is motivated in this paper. It is also found that this improved implosion uniformity is obtained independent of the heat conduction model. This work indicates that significant improvement in performance can be obtained robustly with the proposed spot shapes.« less

Mapping of Low-Frequency Raman Modes in CVD-Grown Transition Metal Dichalcogenides: Layer Number, Stacking Orientation and Resonant Effects

PubMed Central

O’Brien, Maria; McEvoy, Niall; Hanlon, Damien; Hallam, Toby; Coleman, Jonathan N.; Duesberg, Georg S.

2016-01-01

Layered inorganic materials, such as the transition metal dichalcogenides (TMDs), have attracted much attention due to their exceptional electronic and optical properties. Reliable synthesis and characterization of these materials must be developed if these properties are to be exploited. Herein, we present low-frequency Raman analysis of MoS2, MoSe2, WSe2 and WS2 grown by chemical vapour deposition (CVD). Raman spectra are acquired over large areas allowing changes in the position and intensity of the shear and layer-breathing modes to be visualized in maps. This allows detailed characterization of mono- and few-layered TMDs which is complementary to well-established (high-frequency) Raman and photoluminescence spectroscopy. This study presents a major stepping stone in fundamental understanding of layered materials as mapping the low-frequency modes allows the quality, symmetry, stacking configuration and layer number of 2D materials to be probed over large areas. In addition, we report on anomalous resonance effects in the low-frequency region of the WS2 Raman spectrum. PMID:26766208

High-Performance Solid-State Thermionic Energy Conversion Based on 2D van der Waals Heterostructures: A First-Principles Study.

PubMed

Wang, Xiaoming; Zebarjadi, Mona; Esfarjani, Keivan

2018-06-18

Two-dimensional (2D) van der Waals heterostructures (vdWHs) have shown multiple functionalities with great potential in electronics and photovoltaics. Here, we show their potential for solid-state thermionic energy conversion and demonstrate a designing strategy towards high-performance devices. We propose two promising thermionic devices, namely, the p-type Pt-G-WSe 2 -G-Pt and n-type Sc-WSe 2 -MoSe 2 -WSe 2 -Sc. We characterize the thermionic energy conversion performance of the latter using first-principles GW calculations combined with real space Green's function (GF) formalism. The optimal barrier height and high thermal resistance lead to an excellent performance. The proposed device is found to have a room temperature equivalent figure of merit of 1.2 which increases to 3 above 600 K. A high performance with cooling efficiency over 30% of the Carnot efficiency above 450 K is achieved. Our designing and characterization method can be used to pursue other potential thermionic devices based on vdWHs.

KSC-2011-3420

NASA Image and Video Library

2011-05-09

CAPE CANAVERAL, Fla. -- In the Press Site auditorium at NASA's Kennedy Space Center in Florida, NASA managers brief media about the launch status of space shuttle Endeavour's STS-134 mission and announce a new launch date. From left are NASA News Chief Allard Beutel, Space Shuttle Program Launch Integration Manager, Mike Moses and Shuttle Launch Director Mike Leinbach. Technicians replaced and tested the aft load control assembly-2 (ALCA-2) and wiring located in Endeavour's aft avionics bay 5. ALCA-2 distributes power to nine shuttle systems and is believed to have caused fuel line heaters for Endeavour's auxiliary power unit-1 (APU-1) to fail April 29 during the first launch attempt. Launch now is scheduled for May 16 at 8:56 a.m. EDT. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller

Tunneling Photocurrent Assisted by Interlayer Excitons in Staggered van der Waals Hetero-Bilayers.

PubMed

Luong, Dinh Hoa; Lee, Hyun Seok; Neupane, Guru Prakash; Roy, Shrawan; Ghimire, Ganesh; Lee, Jin Hee; Vu, Quoc An; Lee, Young Hee

2017-09-01

Vertically stacked van der Waals (vdW) heterostructures have been suggested as a robust platform for studying interfacial phenomena and related electric/optoelectronic devices. While the interlayer Coulomb interaction mediated by the vdW coupling has been extensively studied for carrier recombination processes in a diode transport, its correlation with the interlayer tunneling transport has not been elucidated. Here, a contrast is reported between tunneling and drift photocurrents tailored by the interlayer coupling strength in MoSe 2 /MoS 2 hetero-bilayers (HBs). The interfacial coupling modulated by thermal annealing is identified by the interlayer phonon coupling in Raman spectra and the emerging interlayer exciton peak in photoluminescence spectra. In strongly coupled HBs, positive photocurrents are observed owing to the inelastic band-to-band tunneling assisted by interlayer excitons that prevail over exciton recombinations. By contrast, weakly coupled HBs exhibit a negative photovoltaic diode behavior, manifested as a drift current without interlayer excitonic emissions. This study sheds light on tailoring the tunneling transport for numerous optoelectronic HB devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-surface charge exfoliation and electrostatically coordinated 2D hetero-layered hybrids

PubMed Central

Yang, Min-Quan; Xu, Yi-Jun; Lu, Wanheng; Zeng, Kaiyang; Zhu, Hai; Xu, Qing-Hua; Ho, Ghim Wei

2017-01-01

At present, the technological groundwork of atomically thin two-dimensional (2D) hetero-layered structures realized by successive thin film epitaxial growth is in principle constrained by lattice matching prerequisite as well as low yield and expensive production. Here, we artificially coordinate ultrathin 2D hetero-layered metal chalcogenides via a highly scalable self-surface charge exfoliation and electrostatic coupling approach. Specifically, bulk metal chalcogenides are spontaneously exfoliated into ultrathin layers in a surfactant/intercalator-free medium, followed by unconstrained electrostatic coupling with a dissimilar transition metal dichalcogenide, MoSe2, into scalable hetero-layered hybrids. Accordingly, surface and interfacial-dominated photocatalysis reactivity is used as an ideal testbed to verify the reliability of diverse 2D ultrathin hetero-layered materials that reveal high visible-light photoreactivity, efficient charge transfer and intimate contact interface for stable cycling and storage purposes. Such a synthetic approach renders independent thickness and composition control anticipated to advance the development of ‘design-and-build' 2D layered heterojunctions for large-scale exploration and applications. PMID:28146147

History of evolution of the concept of medical ethics.

PubMed

Majumdar, Sisir K

2003-01-01

"Time present and time past are both perhaps present in time future and time future contained in time past".--Thomas Steams Eliot (1888-1965), Noble Literature Laureate, 1948. History and evolution of the concept of Medical Ethics is the classical example of this poetic expression. Virtually, every human society has some forces of myth to explain the origin of morality. Indian ethics was philosophical from its very birth. In the Vedas (1500 B.C.), ethics was an integral aspect of philosophical and religious speculation about the nature of reality. The Vedas says how people ought to live and is the oldest philosophical literature in the world. It was the first account of philosophical ethics in human history. The old Testament of (c. 200 B.C.) the Hebrew Bible (Greek--ta biblia--"the books") gives account of God giving the Ten Commandments--the oral and written Law engraved on tablets of Stone to Moses around 13th century B.C. on Mount Sinai (Arabic--Gebel Musa) the Mountain near the tip of the Sinai Peninsula in West Asia.

KSC-2011-5062

NASA Image and Video Library

2011-07-06

CAPE CANAVERAL, Fla. -- In the Press Site auditorium at NASA's Kennedy Space Center in Florida, NASA managers brief media about the launch status of space shuttle Atlantis' STS-135 mission to the International Space Station. Seen here are Public Affairs Officer Candrea Thomas (left), Space Shuttle Program Launch Integration Manager Mike Moses, Shuttle Launch Director Mike Leinbach and Shuttle Weather Officer Kathy Winters. Atlantis and its crew of four are scheduled to lift off at 11:26 a.m. EDT on July 8 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts to the station. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing satellites and return a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Jack Pfaller

Water-level altitudes 2014 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2013 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2014-01-01

Compaction of subsurface sediments (mostly in the fine-grained clay and silt layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2013, measured cumulative compaction at the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.654 ft at the Addicks extensometer. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of clay, silt, and sand and compressibility of the subsurface sediments. Therefore, it is not appropriate to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todt, Michael A.; Isenberg, Allan E.; Nanayakkara, Sanjini U.

Semiconducting transition-metal dichalcogenide (TMD) nanoflake thin films are promising large-area electrodes for photo-electrochemical solar energy conversion applications. However, their energy conversion efficiencies are typically much lower than those of bulk electrodes. It is unclear to what extent this efficiency gap stems from differences among nanoflakes (e.g., area, thickness, and surface structural features). It is also unclear whether individual exfoliated nanoflakes can achieve energy conversion efficiencies similar to those of bulk crystals. Here, we use a single-nanoflake photo-electrochemical approach to show that there are both highly active and completely inactive nanoflakes within a film. For the exfoliated MoSe 2 samples studiedmore » herein, 7% of nanoflakes are highly active champions, whose photocurrent efficiency exceeds that of the bulk crystal. However, 66% of nanoflakes are inactive spectators, which are mostly responsible for the overall lower photocurrent efficiency compared to the bulk crystal. The photocurrent collection efficiency increases with nanoflake area and decreases more at perimeter edges than at interior step edges. These observations, which are hidden in ensemble-level measurements, reveal the underlying performance issues of exfoliated TMD electrodes for photo-electrochemical energy conversion applications.« less

Explicit and Implicit Verbal Response Inhibition in Preschool-Age Children Who Stutter

PubMed Central

Wagovich, Stacy A.

2017-01-01

Purpose The purpose of this study was to examine (a) explicit and implicit verbal response inhibition in preschool children who do stutter (CWS) and do not stutter (CWNS) and (b) the relationship between response inhibition and language skills. Method Participants were 41 CWS and 41 CWNS between the ages of 3;1 and 6;1 (years;months). Explicit verbal response inhibition was measured using a computerized version of the grass–snow task (Carlson & Moses, 2001), and implicit verbal response inhibition was measured using the baa–meow task. Main dependent variables were reaction time and accuracy. Results The CWS were significantly less accurate than the CWNS on the implicit task, but not the explicit task. The CWS also exhibited slower reaction times than the CWNS on both tasks. Between-group differences in performance could not be attributed to working memory demands. Overall, children's performance on the inhibition tasks corresponded with parents' perceptions of their children's inhibition skills in daily life. Conclusions CWS are less effective and efficient than CWNS in suppressing a dominant response while executing a conflicting response in the verbal domain. PMID:28384673

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robey, H. F.; MacGowan, B. J.; Landen, O. L.

Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shapemore » (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (∼0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.« less

High-Throughput Fabrication of Ultradense Annular Nanogap Arrays for Plasmon-Enhanced Spectroscopy.

PubMed

Cai, Hongbing; Meng, Qiushi; Zhao, Hui; Li, Mingling; Dai, Yanmeng; Lin, Yue; Ding, Huaiyi; Pan, Nan; Tian, Yangchao; Luo, Yi; Wang, Xiaoping

2018-06-13

The confinement of light into nanometer-sized metallic nanogaps can lead to an extremely high field enhancement, resulting in dramatically enhanced absorption, emission, and surface-enhanced Raman scattering (SERS) of molecules embedded in nanogaps. However, low-cost, high-throughput, and reliable fabrication of ultra-high-dense nanogap arrays with precise control of the gap size still remains a challenge. Here, by combining colloidal lithography and atomic layer deposition technique, a reproducible method for fabricating ultra-high-dense arrays of hexagonal close-packed annular nanogaps over large areas is demonstrated. The annular nanogap arrays with a minimum diameter smaller than 100 nm and sub-1 nm gap width have been produced, showing excellent SERS performance with a typical enhancement factor up to 3.1 × 10 6 and a detection limit of 10 -11 M. Moreover, it can also work as a high-quality field enhancement substrate for studying two-dimensional materials, such as MoSe 2 . Our method provides an attractive approach to produce controllable nanogaps for enhanced light-matter interaction at the nanoscale.

Two-dimensional materials as catalysts for energy conversion

DOE PAGES

Siahrostami, Samira; Tsai, Charlie; Karamad, Mohammadreza; ...

2016-08-24

Although large efforts have been dedicated to studying two-dimensional materials for catalysis, a rationalization of the associated trends in their intrinsic activity has so far been elusive. In the present work we employ density functional theory to examine a variety of two-dimensional materials, including, carbon based materials, hexagonal boron nitride ( h-BN), transition metal dichalcogenides (e.g. MoS 2, MoSe 2) and layered oxides, to give an overview of the trends in adsorption energies. By examining key reaction intermediates relevant to the oxygen reduction, and oxygen evolution reactions we find that binding energies largely follow the linear scaling relationships observed formore » pure metals. Here, this observation is very important as it suggests that the same simplifying assumptions made to correlate descriptors with reaction rates in transition metal catalysts are also valid for the studied two-dimensional materials. By means of these scaling relations, for each reaction we also identify several promising candidates that are predicted to exhibit a comparable activity to the state-of-the-art catalysts.« less

Directional interlayer spin-valley transfer in two-dimensional heterostructures

DOE PAGES

Schaibley, John R.; Rivera, Pasqual; Yu, Hongyi; ...

2016-12-14

Van der Waals heterostructures formed by two different monolayer semiconductors have emerged as a promising platform for new optoelectronic and spin/valleytronic applications. In addition to its atomically thin nature, a two-dimensional semiconductor heterostructure is distinct from its three-dimensional counterparts due to the unique coupled spin-valley physics of its constituent monolayers. In this paper, we report the direct observation that an optically generated spin-valley polarization in one monolayer can be transferred between layers of a two-dimensional MoSe 2–WSe 2 heterostructure. Using non-degenerate optical circular dichroism spectroscopy, we show that charge transfer between two monolayers conserves spin-valley polarization and is only weaklymore » dependent on the twist angle between layers. Finally, our work points to a new spin-valley pumping scheme in nanoscale devices, provides a fundamental understanding of spin-valley transfer across the two-dimensional interface, and shows the potential use of two-dimensional semiconductors as a spin-valley generator in two-dimensional spin/valleytronic devices for storing and processing information.« less

Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington

NASA Technical Reports Server (NTRS)

Golombek, M. P. (Editor); Edgett, K. S. (Editor); Rice, J. W. , Jr. (Editor)

1995-01-01

Mars Pathfinder will place a single lander on the surface of Mars on July 4, 1997, following a December 1996 launch. As a result of the very successful first Mars Pathfinder Landing Site Workshop, the project has selected the Ares Vallis outflow channel in Chryse Planitia as the landing site. This location is where a large catastrophic outflow channel debouches into the northern lowlands. A second workshop and series of field trips, entitled Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington, were held in Spokane and Moses Lake, Washington. The purpose of the workshop was to provide a focus for learning as much as possible about the Ares Vallis region on Mars before landing there. The rationale is that the more that can be learned about the general area prior to landing, the better scientists will be able interpret the observations made by the lander and rover and place them in the proper geologic context. The field trip included overflights and surface investigations of the Channeled Scabland (an Earth analog for the martian catastrophic outflow channels), focusing on areas particularly analogous to Ares Vallis and the landing site. The overflights were essential for placing the enormous erosional and depositional features of the Channeled Scabland into proper three-dimensional context. The field trips were a joint educational outreach activity involving K-12 science educators, Mars Pathfinder scientists and engineers, and interested scientists from the Mars scientific community. Part 1 of the technical report on this workshop includes a description of the Mars Pathfinder mission, abstracts accepted for presentation at the workshop, an introduction to the Channeled Scabland, and field trip guides for the overflight and two field trips. This part, Part 2, includes the program for the workshop, summaries of the workshop technical sessions, a summary of the field trips and ensuing discussions, late abstracts of workshop presentations, reports on the education and public outreach activities carried out by the educators, and a list of the workshop and field trip participants.

Localized light waves: Paraxial and exact solutions of the wave equation (a review)

NASA Astrophysics Data System (ADS)

Kiselev, A. P.

2007-04-01

Simple explicit localized solutions are systematized over the whole space of a linear wave equation, which models the propagation of optical radiation in a linear approximation. Much attention has been paid to exact solutions (which date back to the Bateman findings) that describe wave beams (including Bessel-Gauss beams) and wave packets with a Gaussian localization with respect to the spatial variables and time. Their asymptotics with respect to free parameters and at large distances are presented. A similarity between these exact solutions and harmonic in time fields obtained in the paraxial approximation based on the Leontovich-Fock parabolic equation has been studied. Higher-order modes are considered systematically using the separation of variables method. The application of the Bateman solutions of the wave equation to the construction of solutions to equations with dispersion and nonlinearity and their use in wavelet analysis, as well as the summation of Gaussian beams, are discussed. In addition, solutions localized at infinity known as the Moses-Prosser “acoustic bullets”, as well as their harmonic in time counterparts, “ X waves”, waves from complex sources, etc., have been considered. Everywhere possible, the most elementary mathematical formalism is used.

Analyzing the application of silicon-silver-2D nanomaterial-Al2O3 heterojunction in plasmonic sensor and its performance evaluation

NASA Astrophysics Data System (ADS)

Sharma, Anuj K.

2018-03-01

A semiconductor-metal-dielectric heterojunction system, generally useful in enhancing the efficiency of solar cells, is explored to design a high performance optical sensor based on surface plasmon resonance in near infrared (NIR). Silicon is considered as light coupling material and different 2D nanomaterials such as graphene, MoS2, and MoSe2 are explored to enhance the sensor's performance in terms of its figure of merit (FOM). An Al2O3 interlayer with a few nanometers of thickness is introduced, which acts as a critical component to significantly enhance the sensor's FOM. It is observed that an Al2O3 interlayer of around 9 nm thickness is able to many-fold upturn the sensor's FOM. As another important finding, silver layer thickness of around 60 nm is found to be highly useful to achieve high values of FOM. It is established through results that operating at longer NIR wavelength leads to greater FOM for any choice of 2D nanomaterial and any thickness of Al2O3 interlayer. Proposed sensor provides significantly greater FOM than previous works on SPR sensors.

Beyond illusion: Psychoanalysis and the question of religious truth.

PubMed

Blass, Rachel B

2004-06-01

In this paper the author critically examines the nature of the positive, reconciliatory attitude towards religion that has become increasingly prevalent within psychoanalytic thinking and writing over the past 20 years. She shows how this positive attitude rests on a change in the nature of the prototype of religion and its reassignment to the realm of illusion, thus making irrelevant an issue most central both to psychoanalysis and to traditional Judeo-Christian belief--the passionate search for truth. The author demonstrates how the concern with truth, and specifically with the truth of religious claims, lies at the basis of the opposition between psychoanalysis and religion but, paradoxically, also provides the common ground for dialogue between the two. She argues that, as Freud developed his ideas regarding the origin of conviction in religious claims in his Moses and monotheism (1939), the nature of this common ground was expanded and the dialogue became potentially more meaningful. The author concludes that meaningful dialogue emerges through recognition of fundamental differences rather than through harmonisation within a realm of illusion. In this light, the present study may also be seen as an attempt to recognise fundamental differences that have been evolving within psychoanalysis itself.

A General Method for the Chemical Synthesis of Large-Scale, Seamless Transition Metal Dichalcogenide Electronics.

PubMed

Li, Li; Guo, Yichuan; Sun, Yuping; Yang, Long; Qin, Liang; Guan, Shouliang; Wang, Jinfen; Qiu, Xiaohui; Li, Hongbian; Shang, Yuanyuan; Fang, Ying

2018-03-01

The capability to directly build atomically thin transition metal dichalcogenide (TMD) devices by chemical synthesis offers important opportunities to achieve large-scale electronics and optoelectronics with seamless interfaces. Here, a general approach for the chemical synthesis of a variety of TMD (e.g., MoS 2 , WS 2 , and MoSe 2 ) device arrays over large areas is reported. During chemical vapor deposition, semiconducting TMD channels and metallic TMD/carbon nanotube (CNT) hybrid electrodes are simultaneously formed on CNT-patterned substrate, and then coalesce into seamless devices. Chemically synthesized TMD devices exhibit attractive electrical and mechanical properties. It is demonstrated that chemically synthesized MoS 2 -MoS 2 /CNT devices have Ohmic contacts between MoS 2 /CNT hybrid electrodes and MoS 2 channels. In addition, MoS 2 -MoS 2 /CNT devices show greatly enhanced mechanical stability and photoresponsivity compared with conventional gold-contacted devices, which makes them suitable for flexible optoelectronics. Accordingly, a highly flexible pixel array based on chemically synthesized MoS 2 -MoS 2 /CNT photodetectors is applied for image sensing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic structures and enhanced optical properties of blue phosphorene/transition metal dichalcogenides van der Waals heterostructures.

PubMed

Peng, Qiong; Wang, Zhenyu; Sa, Baisheng; Wu, Bo; Sun, Zhimei

2016-08-24

As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe2, BlueP/WS2 and BlueP/WSe2 heterostructures. The MoSe2, WS2 or WSe2 layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS2 and BlueP/MoSe2 heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices.

Absorption spectrum and ultrafast response of monolayer and bilayer transition-metal dichalcogenides

NASA Astrophysics Data System (ADS)

Turkowski, Volodymyr; Ramirez-Torres, Alfredo; Rahman, Talat S.

2015-03-01

We apply a combined time-dependent density functional theory and many-body theory approach to examine the absorption spectrum and nonequilibrium response of monolayer and bilayer MoS2, MoSe2, WS2 and WSe2 systems. In particular, we evaluate the possibility of existence of bound states - excitons and trions in the undoped systems. In a previous work we have already demonstrated that the binding energies of these states in the monolayer systems are large which makes them available for room temperature applications. We analyze the possibility of ultrafast electron-hole separation in bilayer systems through inter-layer hole transfer, and show that such a possibility exists, in agreement with experimental observations. For doped systems we consider the possibility of Mahan excitonic states in monolayers and show that the binding energy for these states is of the order of 10 meV. We perform a detailed analysis of the relaxation of doped monolayers excited by ultrafast laser pulse by taking into account electron-phonon scattering effects, and demonstrate that ultrafast (10-100fs) processes, including luminescence, may be relevant for these materials. Work supported in part by DOE Grant No. DOE-DE-FG02-07ER46354.

Geologic map of the Priest Rapids 1:100,000 quadrangle, Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reidel, S.P.; Fecht, K.R.

1993-09-01

This map of the Priest Rapids 1:100,000-scale quadrangle, Washington, shows the geology of one of fifteen complete or partial 1:100,000-scale quadrangles that cover the southeast quadrant of Washington. Geologic maps of these quadrangles have been compiled by geologists with the Washington Division of Geology and Earth Resources (DGER) and Washington State University and are the principal data sources for a 1:250,000scale geologic map of the southeast quadrant of Washington, which is in preparation. Eleven of those quadrangles are being released as DGER open-file reports (listed below). The map of the Wenatchee quadrangle has been published by the US Geological Surveymore » (Tabor and others, 1982), and the Moses Lake (Gulick, 1990a), Ritzville (Gulick, 1990b), and Rosalia (Waggoner, 1990) quadrangles have already been released. The geology of the Priest Rapids quadrangle has not previously been compiled at 1:100,000 scale. Furthermore, this is the first 1:100,000 or smaller scale geologic map of the area to incorporate both bedrock and surficial geology. This map was compiled in 1992, using published and unpublished geologic maps as sources of data.« less

Selenization of CIS and CIGS layers deposited by chemical spray pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, B. J.; Egaas, B.; Velumani, S.

Cu(In1-xGax)Se2 (CIGS) thin films with x=0 (CIS) and x=0.3 (CIGS) were prepared on Mo-coated glass substrate by using chemical spray pyrolysis at a substrate temperature of 350 degrees C, followed by selenization treatment at 550 degrees C in selenium environment under N2 gas flow. X-ray diffraction patterns of as-deposited CIGS layers on Mo showed polycrystalline chalcopyrite phase with an intense (112) plane. Splitting of (204)/(220) and (116)/(312) planes for the film with x=0.3 reveals deviation of tetragonal nature. Field emission scanning electron microscopy cross-sectional images of selenized films showed clear re-crystallization of grains. During the selenization process of the CIGSmore » absorber, a thin interface layer of MoSe2 is formed. Line mapping of Mo/CIGS layer showed more gallium segregation at the interface of back contact resulting in band gap grading. Chemical composition and mapping of the as-deposited and selenized samples were determined by energy dispersive analysis of X-rays. This work leads to fabrication of low cost and large scale Mo/CIGS/CdS/ZnO/ZnO:Al device structure.« less

Constructing the truth: from 'confusion of tongues' to 'constructions in analysis'.

PubMed

Press, Jacques

2006-04-01

The author hypothesizes that the papers Freud wrote in the period 1934-9 constitute a final turning point in his work resulting from an attempt to work through, by means of self-analysis, early traumatic elements reactivated by the conditions of his life in the 1930s. The author emphasizes that the ups and downs of Freud's relationship with Sándor Ferenczi and the mourning which followed his death in 1933 played an important role in this traumatic situation. He suggests that through these last works, Freud pursued a posthumous dialogue with Ferenczi. This working through led Freud, in Moses and monotheism, to an ultimate revision of his theory of trauma, a revision which the author examines in full, in the light of the works of the Egyptologist, Jan Assmann. A new analytical paradigm emerges: that of constructions in analysis developed in the article of the same name. The activity of construction appears as an alternative to the mutual analysis proposed by Ferenczi and is closely bound up with the notion of historical truth. In psychoanalysis, it would mean constructing a historical truth whose anchoring in the material truth of the past is essential, though it should not be confused with it.

National Ignition Facility, High-Energy-Density and Inertial Confinement Fusion, Peer-Review Panel (PRP) Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keane, C. J.

2014-01-28

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is operated as a National Nuclear Security Administration (NNSA) user facility in accordance with Department of Energy (DOE) best practices, including peer-reviewed experiments, regular external reviews of performance, and the use of a management structure that facilitates user and stakeholder feedback. NIF facility time is managed using processes similar to those in other DOE science facilities and is tailored to meet the mix of missions and customers that NIF supports. The NIF Governance Plan describes the process for allocating facility time on NIF and for creating the shot schedule.more » It also includes the flow of responsibility from entity to entity. The plan works to ensure that NIF meets its mission goals using the principles of scientific peer review, including transparency and cooperation among the sponsor, the NIF staff, and the various user communities. The NIF Governance Plan, dated September 28, 2012, was accepted and signed by LLNL Director Parney Albright, NIF Director Ed Moses, and Don Cook and Thomas D’Agostino of NNSA. Figure 1 shows the organizational structure for NIF Governance.« less

Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

PubMed

Dai, Rui; Zhang, Anqi; Pan, Zhichang; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Hu, Linfeng; Zheng, Gengfeng

2016-05-01

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Large-area synthesis of monolayered MoS(2(1-x))Se(2x) with a tunable band gap and its enhanced electrochemical catalytic activity.

PubMed

Yang, Lei; Fu, Qi; Wang, Wenhui; Huang, Jian; Huang, Jianliu; Zhang, Jingyu; Xiang, Bin

2015-06-21

"Band gap engineering" in two-dimensional (2D) materials plays an important role in tailoring their physical and chemical properties. The tuning of the band gap is typically achieved by controlling the composition of the semiconductor alloys. However, large-area preparation of 2D alloys remains a major challenge. Here, we report the large-area synthesis of high-quality monolayered MoS2(1-x)Se2x with a size coverage of hundreds of microns using a chemical vapor deposition method. The photoluminescence (PL) spectroscopy results confirm the tunable band gap in MoS2(1-x)Se2x, which is modulated by varying the Se content. Atomic-scale analysis was performed and the chemical composition was characterized using high-resolution scanning transmission electron microscopy and X-ray photoemission spectroscopy. With the introduction of Se into monolayered MoS2, it leads to enhanced catalytic activity in an electrochemical reaction for hydrogen generation, compared to monolayered MoS2 and MoSe2. It is promising as a potential alternative to expensive noble metals.

Hydrodynamic instability experiments with three-dimensional modulations at the National Ignition Facility

DOE PAGES

Smalyuk, V. A.; Weber, S. V.; Casey, D. T.; ...

2015-06-18

The first hydrodynamic instability growth measurements with three-dimensional (3D) surface-roughness modulations were performed on CH shell spherical implosions at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)]. The initial capsule outer-surface amplitudes were increased approximately four times, compared with the standard specifications, to increase the signal-to-noise ratio, helping to qualify a technique for measuring small 3D modulations. The instability growth measurements were performed using x-ray through-foil radiography based on time-resolved pinhole imaging. Averaging over 15 similar images significantly increased the signal-to-noise ratio, making possible a comparison with 3Dmore » simulations. At a convergence ratio of ~2.4, the measured modulation levels were ~3 times larger than those simulated based on the growth of the known imposed initial surface modulations. Several hypotheses are discussed, including increased instability growth due to modulations of the oxygen content in the bulk of the capsule. In conclusion, future experiments will be focused on measurements with standard 3D ‘native-roughness’ capsules as well as with deliberately imposed oxygen modulations.« less

Protoptila (Trichoptera) of Costa Rica and a Review of the Central American Fauna

NASA Astrophysics Data System (ADS)

Blahnik, R. J.; Holzenthal, R. W.

2005-05-01

Protoptila is the most diverse of the genera in the subfamily Protoptilinae of the family Glossosomatidae, currently with 80 species, but many more from the Neotropics awaiting description. Fourteen species occur in the United States, only one of which is also known to occur in Mexico. This compares to 38 species and one subspecies (or about half of the total for the genus) currently known from Central America, mostly described in papers by Mosely and Flint. Although the majority of these, or some 27 species, occur in Mexico, this probably more closely reflects the historical intensity of collecting rather than the real diversity by region. In Costa Rica, 11 species are currently known, 8 of which are restricted in distribution to Costa Rica, or Costa Rica and Panama, and only 3 with distributions extending to Mexico. We are describing an additional 8 species from Costa Rica, bringing to 19 the number of species now known from the country. This represents an incredible diversity for such a small country and also a very high level of implied endemism, even considering the likelihood that some of the species will be found to have wider distributions.

Multifunctional tunneling devices based on graphene/h-BN/MoSe2 van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Cheng, Ruiqing; Wang, Feng; Yin, Lei; Xu, Kai; Ahmed Shifa, Tofik; Wen, Yao; Zhan, Xueying; Li, Jie; Jiang, Chao; Wang, Zhenxing; He, Jun

2017-04-01

The vertically stacked devices based on van der Waals heterostructures (vdWHs) of two-dimensional layered materials (2DLMs) have attracted considerable attention due to their superb properties. As a typical structure, graphene/hexagonal boron nitride (h-BN)/graphene vdWH has been proved possible to make tunneling devices. Compared with graphene, transition metal dichalcogenides possess intrinsic bandgap, leading to high performance of electronic devices. Here, tunneling devices based on graphene/h-BN/MoSe2 vdWHs are designed for multiple functions. On the one hand, the device shows a typical tunneling field-effect transistor behavior. A high on/off ratio of tunneling current (5 × 103) and an ultrahigh current rectification ratio (7 × 105) are achieved, which are attributed to relatively small electronic affinity of MoSe2 and optimized thickness of h-BN. On the other hand, the same structure also realizes 2D non-volatile memory with a high program/erase current ratio (>105), large memory window (˜150 V from ±90 V), and good retention characteristic. These results could enhance the fundamental understanding of tunneling behavior in vdWHs and contribute to the design of ultrathin rectifiers and memory based on 2DLMs.

Breast-feeding. The roots.

PubMed

Ben-Nun, L

2006-12-01

Although breast milk provides the best nutrition for the infant, breast-feeding has been decreasing with the growth in use of prepared milk formulas. This paper evaluates the available biblical literature dealing with breast-feeding. The research is unique in character, as it combines contemporary medical knowledge with presentation of cases taken from ancient history. We include no commentaries, but refer only to the words of the Bible exactly as written. Biblical texts relating to breast-feeding were examined and the cases of biblical characters who were breast-fed were studied. The great historical figures such as Isaac, Rebecca, Moses, Samuel, and Joash were breast-fed, openly or secretly. If the biological mother was unable to nurse her child, a wet nurse took over the feeding. Breast-feeding was the only way infants could survive at that time. Weaning day was very important and was celebrated. The wet nurse played an important role in family life, in some cases remaining to live with the infant after weaning, through childhood and even into adulthood. In spite of advanced technology that provides artificial infant formulas, contemporary mothers, just like biblical mothers, should be encouraged to breast-feed their infants.

Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE PAGES

Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; ...

2015-06-02

High Density Carbon (HDC or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a DT layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightlymore » oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 x 10¹⁵ neutrons, 40% of the 1D simulated yield.« less

Accelerated carrier recombination by grain boundary/edge defects in MBE grown transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Chen, Ke; Roy, Anupam; Rai, Amritesh; Movva, Hema C. P.; Meng, Xianghai; He, Feng; Banerjee, Sanjay K.; Wang, Yaguo

2018-05-01

Defect-carrier interaction in transition metal dichalcogenides (TMDs) plays important roles in carrier relaxation dynamics and carrier transport, which determines the performance of electronic devices. With femtosecond laser time-resolved spectroscopy, we investigated the effect of grain boundary/edge defects on the ultrafast dynamics of photoexcited carrier in molecular beam epitaxy (MBE)-grown MoTe2 and MoSe2. We found that, comparing with exfoliated samples, the carrier recombination rate in MBE-grown samples accelerates by about 50 times. We attribute this striking difference to the existence of abundant grain boundary/edge defects in MBE-grown samples, which can serve as effective recombination centers for the photoexcited carriers. We also observed coherent acoustic phonons in both exfoliated and MBE-grown MoTe2, indicating strong electron-phonon coupling in this materials. Our measured sound velocity agrees well with the previously reported result of theoretical calculation. Our findings provide a useful reference for the fundamental parameters: carrier lifetime and sound velocity and reveal the undiscovered carrier recombination effect of grain boundary/edge defects, both of which will facilitate the defect engineering in TMD materials for high speed opto-electronics.

Broadband ultrafast nonlinear absorption and nonlinear refraction of layered molybdenum dichalcogenide semiconductors

NASA Astrophysics Data System (ADS)

Wang, Kangpeng; Feng, Yanyan; Chang, Chunxia; Zhan, Jingxin; Wang, Chengwei; Zhao, Quanzhong; Coleman, Jonathan N.; Zhang, Long; Blau, Werner J.; Wang, Jun

2014-08-01

A series of layered molybdenum dichalcogenides, i.e., MoX2 (X = S, Se and Te), were prepared in cyclohexyl pyrrolidinone by a liquid-phase exfoliation technique. The high quality of the two-dimensional nanostructures was verified by transmission electron microscopy and absorption spectroscopy. Open- and closed-aperture Z-scans were employed to study the nonlinear absorption and nonlinear refraction of the MoX2 dispersions, respectively. All the three-layered nanostructures exhibit prominent ultrafast saturable absorption (SA) for both femtosecond (fs) and picosecond (ps) laser pulses over a broad wavelength range from the visible to the near infrared. While the dispersions treated with low-speed centrifugation (1500 rpm) have an SA response, and the MoS2 and MoSe2 dispersions after higher speed centrifugation (10 000 rpm) possess two-photon absorption for fs pulses at 1030 nm, which is due to the significant reduction of the average thickness of the nanosheets; hence, the broadening of band gap. In addition, all dispersions show obvious nonlinear self-defocusing for ps pulses at both 1064 nm and 532 nm, resulting from the thermally-induced nonlinear refractive index. The versatile ultrafast nonlinear properties imply a huge potential of the layered MoX2 semiconductors in the development of nanophotonic devices, such as mode-lockers, optical limiters, optical switches, etc.A series of layered molybdenum dichalcogenides, i.e., MoX2 (X = S, Se and Te), were prepared in cyclohexyl pyrrolidinone by a liquid-phase exfoliation technique. The high quality of the two-dimensional nanostructures was verified by transmission electron microscopy and absorption spectroscopy. Open- and closed-aperture Z-scans were employed to study the nonlinear absorption and nonlinear refraction of the MoX2 dispersions, respectively. All the three-layered nanostructures exhibit prominent ultrafast saturable absorption (SA) for both femtosecond (fs) and picosecond (ps) laser pulses over a broad wavelength range from the visible to the near infrared. While the dispersions treated with low-speed centrifugation (1500 rpm) have an SA response, and the MoS2 and MoSe2 dispersions after higher speed centrifugation (10 000 rpm) possess two-photon absorption for fs pulses at 1030 nm, which is due to the significant reduction of the average thickness of the nanosheets; hence, the broadening of band gap. In addition, all dispersions show obvious nonlinear self-defocusing for ps pulses at both 1064 nm and 532 nm, resulting from the thermally-induced nonlinear refractive index. The versatile ultrafast nonlinear properties imply a huge potential of the layered MoX2 semiconductors in the development of nanophotonic devices, such as mode-lockers, optical limiters, optical switches, etc. Electronic supplementary information (ESI) available: Electron scattering patterns from TEM characterizations of MX2 nanosheets; CA Z-scan results of graphene dispersions in the ps region. See DOI: 10.1039/c4nr02634a

Combinatorial investigation of the effects of sodium on Cu 2ZnSnSe4 polycrystalline thin films

NASA Astrophysics Data System (ADS)

Gibbs, Alex Hilton

Cu2ZnSnSe4 (CZTSe) possess highly suitable optical and electronic properties for use as an absorber layer in thin film solar cells. CZTSe also has potential to achieve terawatt level solar energy production due to its inexpensive and abundant material constituents. Currently, fabricating CZTSe devices with the expected theoretical performance has not been achieved, making the growth and formation of CZTSe an interesting topic of research. In this work, a two-step vacuum fabrication process consisting of RF co-sputtering followed by reactive annealing was explored as a viable technique for synthesizing CZTSe thin films. Furthermore, the enhancement of the fabrication process by the incorporation of sodium during annealing was studied using a combinatorial approach. Film composition was analyzed using electron dispersive spectroscopy. Structure, phase morphology, and formation were determined using scanning electron microscopy, x-ray diffraction, atomic force microscopy and raman spectroscopy. Optical and electronic properties were characterized using UV-Vis and Voc were measurements under a one sun solar simulator. RF co-sputtering CuSe, ZnSe, and SnSe precursors produced films with good thickness uniformity, adhesion and stoichiometry control over 3 x 3 in 2 substrates. Composition measurements showed that the precursor films maintained stability during an annealing process of 580° C for 20 minutes producing near stoichiometric CZTSe. However, grain size was small with an average diameter of 350 nm. The CZTSe film produced by this process exhibited a suitable absorption coefficient of > 104 cm-1 and aband gap near 1.0 eV. The film also produced an XRD pattern consistent with tetragonal CZTSe with no secondary phase formation with the exception of approximately 12.5 nm of interfacial MoSe2 formation at the back contact. The combinatorial investigation of the influence of sodium on CZTSe growth and morphology was achieved using a custom built constant withdraw shutter to evaporate NaF with a 0-60 nm thickness spread on the substrate prior to precursor sputtering. This experiment showed that the incorporation of NaF did enhance grain size; however, there was little correlation with initial NaF composition observed. It is concluded that NaF undergoes high degree of vapor transport and readily distributes nonuniformly throughout the film during the annealing process and also potentially escapes the annealing environment if not properly contained. An experiment on achieving Na incorporation by diffusion from a soda lime glass substrate resulted in a far more uniform enhancement of grain growth. The experiment also revealed that NaF greatly reduced precursor film adhesion to the substrate due to the hygroscopic nature of NaF. X-ray diffraction measurements also showed that the addition of the NaF layer was could potentially suppress the formation of MoSe2.

Adaptation of machine translation for multilingual information retrieval in the medical domain.

PubMed

Pecina, Pavel; Dušek, Ondřej; Goeuriot, Lorraine; Hajič, Jan; Hlaváčová, Jaroslava; Jones, Gareth J F; Kelly, Liadh; Leveling, Johannes; Mareček, David; Novák, Michal; Popel, Martin; Rosa, Rudolf; Tamchyna, Aleš; Urešová, Zdeňka

2014-07-01

We investigate machine translation (MT) of user search queries in the context of cross-lingual information retrieval (IR) in the medical domain. The main focus is on techniques to adapt MT to increase translation quality; however, we also explore MT adaptation to improve effectiveness of cross-lingual IR. Our MT system is Moses, a state-of-the-art phrase-based statistical machine translation system. The IR system is based on the BM25 retrieval model implemented in the Lucene search engine. The MT techniques employed in this work include in-domain training and tuning, intelligent training data selection, optimization of phrase table configuration, compound splitting, and exploiting synonyms as translation variants. The IR methods include morphological normalization and using multiple translation variants for query expansion. The experiments are performed and thoroughly evaluated on three language pairs: Czech-English, German-English, and French-English. MT quality is evaluated on data sets created within the Khresmoi project and IR effectiveness is tested on the CLEF eHealth 2013 data sets. The search query translation results achieved in our experiments are outstanding - our systems outperform not only our strong baselines, but also Google Translate and Microsoft Bing Translator in direct comparison carried out on all the language pairs. The baseline BLEU scores increased from 26.59 to 41.45 for Czech-English, from 23.03 to 40.82 for German-English, and from 32.67 to 40.82 for French-English. This is a 55% improvement on average. In terms of the IR performance on this particular test collection, a significant improvement over the baseline is achieved only for French-English. For Czech-English and German-English, the increased MT quality does not lead to better IR results. Most of the MT techniques employed in our experiments improve MT of medical search queries. Especially the intelligent training data selection proves to be very successful for domain adaptation of MT. Certain improvements are also obtained from German compound splitting on the source language side. Translation quality, however, does not appear to correlate with the IR performance - better translation does not necessarily yield better retrieval. We discuss in detail the contribution of the individual techniques and state-of-the-art features and provide future research directions. Copyright © 2014 Elsevier B.V. All rights reserved.

The Collision of Comet Shoemaker-Levy 9 and Jupiter

NASA Astrophysics Data System (ADS)

Noll, Keith S.; Weaver, Harold A.; Feldman, Paul D.

2006-11-01

Participants; Preface; 1. The orbital motion and impact circumstances of Comet Shoemaker-Levy 9 Paul W. Chodas and Donald K. Yeomans; 2. Observational constraints on the composition and nature of Comet D/Shoemaker-Levy 9 Jacques Crovisier; 3. Tidal breakup of the nucleus of Comet Shoemaker-Levy 9 Zdenek Sekanina; 4. Earth-based observations of impact phenomena Philip D. Nicholson; 5. HST imaging of Jupiter shortly after each impact: plumes and fresh sites Heidi B. Hammel; 6. Galileo observations of the impacts Clark R. Chapman; 7. Models of fragment penetration and fireball evolution David A. Crawford; 8. Entry and fireball models vs. observations: what have we learned? Mordecai-Mark Mac Low; 9. Dynamics and chemistry of SL9 plumes Kevin Zahnle; 10. Chemistry induced by the impacts: observations Emmanuel Lellouch; 11. SL9 impact chemistry: long-term photochemical evolution Julianne I. Moses; 12. Particulate matter in Jupiter's atmosphere from the impacts of Comet P/Shoemaker-Levy 9 Robert A. West; 13. Jupiter's post-impact atmospheric thermal response Barney J. Conrath; 14. Growth and dispersion of the Shoemaker-Levy 9 impact features from HST imaging Reta F. Beebe; 15. Waves from the Shoemaker-Levy 9 impacts Andrew P. Ingersoll and Hiroo Kanamori; 16. Jovian magnetospheric and auroral effects of the SL9 impacts Wing-Huen Ip.

Vacancy-Induced Formation and Growth of Inversion Domains in Transition-Metal Dichalcogenide Monolayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Junhao; Pantelides, Sokrates T.; Zhou, Wu

2015-04-23

Sixty degree grain boundaries in semiconducting transition-metal dichalcogenide (TMDC) monolayers have been shown to act as conductive channels that have profound influence on both the transport properties and exciton behavior of the monolayers. We show that annealing TMDC monolayers at high temperature induces the formation of large-scale inversion domains surrounded by such 60° grain boundaries. To study the formation mechanism of such inversion domains, we use the electron beam in a scanning transmission electron microscope to activate the dynamic process within pristine TMDC monolayers. Moreover, the electron beam acts to generate chalcogen vacancies in TMDC monolayers and provide energy formore » them to undergo structural evolution. We directly visualize the nucleation and growth of such inversion domains and their 60° grain boundaries atom-by-atom within a MoSe 2 monolayer and explore their formation mechanism. Combined with density functional theory, we conclude that the nucleation of the inversion domains and migration of their 60° grain boundaries are driven by the collective evolution of Se vacancies and subsequent displacement of Mo atoms, where such a dynamical process reduces the vacancy-induced lattice shrinkage and stabilizes the system. Our results can help to understand the performance of such materials under severe conditions (e.g., high temperature).« less

Capsule implosion optimization during the indirect-drive National Ignition Campaign

NASA Astrophysics Data System (ADS)

Landen, O. L.; Edwards, J.; Haan, S. W.; Robey, H. F.; Milovich, J.; Spears, B. K.; Weber, S. V.; Clark, D. S.; Lindl, J. D.; MacGowan, B. J.; Moses, E. I.; Atherton, J.; Amendt, P. A.; Boehly, T. R.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Frenje, J. A.; Glenzer, S. H.; Hamza, A.; Hammel, B. A.; Hicks, D. G.; Hoffman, N.; Izumi, N.; Jones, O. S.; Kilkenny, J. D.; Kirkwood, R. K.; Kline, J. L.; Kyrala, G. A.; Marinak, M. M.; Meezan, N.; Meyerhofer, D. D.; Michel, P.; Munro, D. H.; Olson, R. E.; Nikroo, A.; Regan, S. P.; Suter, L. J.; Thomas, C. A.; Wilson, D. C.

2011-05-01

Capsule performance optimization campaigns will be conducted at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition. The campaigns will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models using a variety of ignition capsule surrogates before proceeding to cryogenic-layered implosions and ignition experiments. The quantitative goals and technique options and down selections for the tuning campaigns are first explained. The computationally derived sensitivities to key laser and target parameters are compared to simple analytic models to gain further insight into the physics of the tuning techniques. The results of the validation of the tuning techniques at the OMEGA facility [J. M. Soures et al., Phys. Plasmas 3, 2108 (1996)] under scaled hohlraum and capsule conditions relevant to the ignition design are shown to meet the required sensitivity and accuracy. A roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget. Finally, we show how the tuning precision will be improved after a number of shots and iterations to meet an acceptable level of residual uncertainty.

Probing Anisotropic Thermal Conductivity of Transition Metal Dichalcogenides MX2 (M = Mo, W and X = S, Se) using Time-Domain Thermoreflectance.

PubMed

Jiang, Puqing; Qian, Xin; Gu, Xiaokun; Yang, Ronggui

2017-09-01

Transition metal dichalcogenides (TMDs) are a group of layered 2D semiconductors that have shown many intriguing electrical and optical properties. However, the thermal transport properties in TMDs are not well understood due to the challenges in characterizing anisotropic thermal conductivity. Here, a variable-spot-size time-domain thermoreflectance approach is developed to simultaneously measure both the in-plane and the through-plane thermal conductivity of four kinds of layered TMDs (MoS 2 , WS 2 , MoSe 2 , and WSe 2 ) over a wide temperature range, 80-300 K. Interestingly, it is found that both the through-plane thermal conductivity and the Al/TMD interface conductance depend on the modulation frequency of the pump beam for all these four compounds. The frequency-dependent thermal properties are attributed to the nonequilibrium thermal resistance between the different groups of phonons in the substrate. A two-channel thermal model is used to analyze the nonequilibrium phonon transport and to derive the intrinsic thermal conductivity at the thermal equilibrium limit. The measurements of the thermal conductivities of bulk TMDs serve as an important benchmark for understanding the thermal conductivity of single- and few-layer TMDs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pre-modern Islamic medical ethics and Graeco-Islamic-Jewish embryology.

PubMed

Ghaly, Mohammed

2014-02-01

This article examines the, hitherto comparatively unexplored, reception of Greek embryology by medieval Muslim jurists. The article elaborates on the views attributed to Hippocrates (d. ca. 375 BC), which received attention from both Muslim physicians, such as Avicenna (d. 1037), and their Jewish peers living in the Muslim world including Ibn Jumay' (d. ca. 1198) and Moses Maimonides (d. 1204). The religio-ethical implications of these Graeco-Islamic-Jewish embryological views were fathomed out by the two medieval Muslim jurists Shihāb al-Dīn al-Qarāfī (d. 1285) and Ibn al-Qayyim (d. 1350). By putting these medieval religio-ethical discussions into the limelight, the article aims to argue for a two-pronged thesis. Firstly, pre-modern medical ethics did exist in the Islamic tradition and available evidence shows that this field had a multidisciplinary character where the Islamic scriptures and the Graeco-Islamic-Jewish medical legacy were highly intertwined. This information problematizes the postulate claiming that medieval Muslim jurists were hostile to the so-called 'ancient sciences'. Secondly, these medieval religio-ethical discussions remain playing a significant role in shaping the nascent field of contemporary Islamic bioethics. However, examining the exact character and scope of this role still requires further academic ventures. © 2013 John Wiley & Sons Ltd.

KSC-2011-5333

NASA Image and Video Library

2011-07-08

CAPE CANAVERAL, Fla. -- Members of the media gather for a post-launch news conference held in the Press Site auditorium at NASA's Kennedy Space Center in Florida, following the successful launch of space shuttle Atlantis on its STS-135 mission to the International Space Station. Seen here are NASA Public Affairs Officer Mike Curie (left) moderator; Associate Administrator for Space Operations Bill Gerstenmaier, Kennedy Center Director Bob Cabana, Shuttle Program Launch Integration Manager Mike Moses, and Shuttle Launch Director Mike Leinbach. Atlantis began its final flight at 11:29 a.m. EDT on July 8. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Jim Grossmann

KSC-2011-5332

NASA Image and Video Library

2011-07-08

CAPE CANAVERAL, Fla. -- Members of the media gather for a post-launch news conference held in the Press Site auditorium at NASA's Kennedy Space Center in Florida, following the successful launch of space shuttle Atlantis on its STS-135 mission to the International Space Station. Seen here are NASA Public Affairs Officer Mike Curie (left) moderator; Associate Administrator for Space Operations Bill Gerstenmaier, Kennedy Center Director Bob Cabana, Shuttle Program Launch Integration Manager Mike Moses, and Shuttle Launch Director Mike Leinbach. Atlantis began its final flight at 11:29 a.m. EDT on July 8. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Jim Grossmann

KSC-2011-5337

NASA Image and Video Library

2011-07-08

CAPE CANAVERAL, Fla. -- Members of the media gather for a post-launch news conference held in the Press Site auditorium at NASA's Kennedy Space Center in Florida, following the successful launch of space shuttle Atlantis on its STS-135 mission to the International Space Station. Seen here are NASA Public Affairs Officer Mike Curie (left) moderator; Associate Administrator for Space Operations Bill Gerstenmaier, Kennedy Center Director Bob Cabana, Shuttle Program Launch Integration Manager Mike Moses, and Shuttle Launch Director Mike Leinbach. Atlantis began its final flight at 11:29 a.m. EDT on July 8. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

KSC-2011-5334

NASA Image and Video Library

2011-07-08

CAPE CANAVERAL, Fla. -- Members of the media gather for a post-launch news conference held in the Press Site auditorium at NASA's Kennedy Space Center in Florida, following the successful launch of space shuttle Atlantis on its STS-135 mission to the International Space Station. Seen here are NASA Public Affairs Officer Mike Curie (left) moderator; Associate Administrator for Space Operations Bill Gerstenmaier, Kennedy Center Director Bob Cabana, Shuttle Program Launch Integration Manager Mike Moses, and Shuttle Launch Director Mike Leinbach. Atlantis began its final flight at 11:29 a.m. EDT on July 8. STS-135 will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett

Characterization of efficiency-limiting resistance losses in monolithically integrated Cu(In,Ga)Se2 solar modules

PubMed Central

Yoon, Ju-Heon; Park, Jong-Keuk; Kim, Won Mok; Lee, JinWoo; Pak, Hisun; Jeong, Jeung-hyun

2015-01-01

The cell-to-module efficiency gap in Cu(In,Ga)Se2 (CIGS) monolithically integrated solar modules is enhanced by contact resistance between the Al-doped ZnO (AZO) and Mo back contact layers, the P2 contact, which connects adjacent cells. The present work evaluated the P2 contact resistance, in addition to the TCO resistance, using an embedded transmission line structure in a commercial-grade module without using special sample fabrication methods. The AZO layers between cells were not scribed; instead, the CIGS/CdS/i-ZnO/AZO device was patterned in a long stripe to permit measurement of the Mo electrode pair resistance over current paths through two P2 contacts (Mo/AZO) and along the AZO layer. The intercept and slope of the resistance as a function of the electrode interval yielded the P2 contact resistance and the TCO resistance, respectively. Calibration of the parasitic resistances is discussed as a method of improving the measurement accuracy. The contribution of the P2 contact resistance to the series resistance was comparable to that of the TCO resistance, and its origin was attributed to remnant MoSe2 phases in the P2 region, as verified by transmission electron microscopy. PMID:25573530

Interlayer Coupling and Gate-Tunable Excitons in Transition Metal Dichalcogenide Heterostructures

DOE PAGES

Gao, Shiyuan; Yang, Li; Spataru, Catalin Dan

2017-11-22

Bilayer van der Waals (vdW) heterostructures such as MoS 2/WS 2 and MoSe 2/WSe 2 have attracted much attention recently, particularly because of their type II band alignments and the formation of interlayer exciton as the lowest-energy excitonic state. In this work, we calculate the electronic and optical properties of such heterostructures with the first-principles GW+Bethe–Salpeter Equation (BSE) method and reveal the important role of interlayer coupling in deciding the excited-state properties, including the band alignment and excitonic properties. Our calculation shows that due to the interlayer coupling, the low energy excitons can be widely tuned by a vertical gatemore » field. In particular, the dipole oscillator strength and radiative lifetime of the lowest energy exciton in these bilayer heterostructures is varied by over an order of magnitude within a practical external gate field. We also build a simple model that captures the essential physics behind this tunability and allows the extension of the ab initio results to a large range of electric fields. In conclusion, our work clarifies the physical picture of interlayer excitons in bilayer vdW heterostructures and predicts a wide range of gate-tunable excited-state properties of 2D optoelectronic devices.« less

Formation of nanooctahedra in molybdenum disulfide and molybdenum diselenide using pulsed laser vaporization.

PubMed

Parilla, Philip A; Dillon, Anne C; Parkinson, Bruce A; Jones, Kim M; Alleman, Jeff; Riker, Gerald; Ginley, David S; Heben, Michael J

2004-05-20

Pulsed laser vaporization has been used to produce nanooctahedra of MoS2 and MoSe2. The nanooctahedra primarily form in two- or three-layer nested octahedra, although nesting up to five layers has been observed. Tilting the TEM sample stage and mapping how the images of single particles transformed provided the evidence to verify their octahedral geometry. Analysis of 30 two- and three-layered octahedra showed that their outer edge lengths clustered at approximately 3.8 nm and approximately 5.1 nm, respectively. This discreet sizing and the high symmetry of these closed nanooctahedra represent the closest inorganic analogy yet to the carbon fullerenes. The geometrical implications for forming octahedra from these layered compounds are investigated by considering different atomic arrangements assuming either trigonal prismatic or octahedral coordination around the Mo atom and yields two possible configurations for the actual structure of the nanooctahedra. A preliminary survey of pulsed laser vaporization of other layered metal chalcogenides shows that these dichalcogenides differ in their tendency to form small closed layered fullerene-like structures. These materials can be ranked from highest tendency to lowest as follows: NbSe2, WS2, WSe2, SnS2, TaS2, GaS, ReS2, and MoTe2.

Interlayer Exciton Optoelectronics in a 2D Heterostructure p-n Junction.

PubMed

Ross, Jason S; Rivera, Pasqual; Schaibley, John; Lee-Wong, Eric; Yu, Hongyi; Taniguchi, Takashi; Watanabe, Kenji; Yan, Jiaqiang; Mandrus, David; Cobden, David; Yao, Wang; Xu, Xiaodong

2017-02-08

Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe 2 -WSe 2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p-n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the direct observation of resonant optical excitation of the interlayer exciton. The resulting photocurrent amplitude from the interlayer exciton is about 200 times smaller than the resonant excitation of intralayer exciton. This implies that the interlayer exciton oscillator strength is 2 orders of magnitude smaller than that of the intralayer exciton due to the spatial separation of electron and hole to the opposite layers. These results lay the foundation for exploiting the interlayer exciton in future 2D heterostructure optoelectronic devices.

KSC-2009-6402

NASA Image and Video Library

2009-11-16

CAPE CANAVERAL, Fla. - A post-launch news conference is held in the NASA Press Site auditorium at NASA's Kennedy Space Center in Florida after the successful launch of space shuttle Atlantis. From left are Public Affairs moderator Mike Curie; Bill Gerstenmaier, associate administrator for Space Operations; Mike Moses, chair, Mission Management Team; and Mike Leinbach, space shuttle launch director. Liftoff of Atlantis on its STS-129 mission came at 2:28 p.m. EST Nov. 16 from Launch Pad 39A. Aboard are crew members Commander Charles O. Hobaugh; Pilot Barry E. Wilmore; and Mission Specialists Leland Melvin, Randy Bresnik, Mike Foreman and Robert L. Satcher Jr. On STS-129, the crew will deliver two ExPRESS Logistics Carriers to the International Space Station, the largest of the shuttle's cargo carriers, containing 15 spare pieces of equipment including two gyroscopes, two nitrogen tank assemblies, two pump modules, an ammonia tank assembly and a spare latching end effector for the station's robotic arm. Atlantis will return to Earth a station crew member, Nicole Stott, who has spent more than two months aboard the orbiting laboratory. STS-129 is slated to be the final space shuttle Expedition crew rotation flight. For information on the STS-129 mission and crew, visit http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts129/index.html. Photo credit: NASA/Kim Shiflett

X-ray driven implosions at ignition relevant velocities on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B.; MacKinnon, A. J.; Hicks, D. G.

2013-05-15

Backlit convergent ablator experiments on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] are indirect drive implosions that study the inflight dynamics of an imploding capsule. Side-on, backlit radiography provides data used by the National Ignition Campaign to measure time-dependent properties of the capsule ablator including its center of mass radius, velocity, and unablated mass. Previously, Callahan [D. A. Callahan et al., Phys. Plasmas 19, 056305 (2012)] and Hicks [D. H. Hicks et al., Phys. Plasmas 19, 122702 (2012)] reported backlit convergent ablator experiments demonstrating velocities approaching those required for ignition. This paper focusesmore » on implosion performance data in the “rocket curve” plane, velocity vs. ablator mass. These rocket curve data, along with supporting numerical simulations, show that the nominal 195 μm-thick ignition capsule would reach the ignition velocity goal V = 370 km/s with low ablator mass remaining–below the goal of M = 0.25 mg. This finding led to experiments with thicker capsule ablators. A recent symmetry capsule experiment with a 20 μm thicker capsule driven by 520 TW, 1.86 MJ laser pulse (along with a companion backlit convergent ablator experiment) appears to have demonstrated V≥350 km/s with ablator mass remaining above the ignition goal.« less

Alloying effect on bright-dark exciton states in ternary monolayer Mo x W1-x Se2

NASA Astrophysics Data System (ADS)

Liu, Yanping; Tom, Kyle; Zhang, Xiaowei; Lou, Shuai; Liu, Yin; Yao, Jie

2017-07-01

Binary transition metal dichalcogenides (TMDCs) in the class MX2 (M = Mo, W; X = S, Se) have been widely investigated for potential applications in optoelectronics and nanoelectronics. Recently, alloy-based monolayers of TMDCs have provided a stable and versatile technique to tune the physical properties and optimize them for potential applications. Here, we present experimental evidence for the existence of an intermediate alloy state between the MoSe2-like and the WSe2-like behavior of the neutral exciton (X 0) using temperature-dependent photoluminescence (PL) of the monolayer Mo x W1-x Se2 alloy. The existence of a maximum PL intensity around 120 K can be explained by the competition between the thermally activated bright states and the non-radiative quenching of the bright states. Moreover, we also measured localized exciton (XB ) PL peak in the alloy and the observed behavior agrees well with a model previously proposed for the 3D case, which indicates the theory also applies to 2D systems. Our results not only shed light on bright-dark states and localized exciton physics of 2D semiconductors, but also offer a new route toward the control of the bright-dark transition and tailoring optical properties of 2D semiconductors through defect engineering.

Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B., E-mail: meezan1@llnl.gov; Hopkins, L. F. Berzak; Pape, S. Le

2015-06-15

High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape.more » Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 10{sup 15} neutrons, 40% of the 1D simulated yield.« less

Persistent photoconductivity in two-dimensional Mo 1-xW xSe 2–MoSe 2 van der Waals heterojunctions

DOE PAGES

Puretzky, Alexander A.; Basile, Leonardo; Idrobo, Juan Carlos; ...

2016-02-16

Van der Waals (vdW) heterojunctions consisting of vertically-stacked individual or multiple layers of two-dimensional (2D) layered semiconductors, especially the transition metal dichalcogenides (TMDs), are fascinating new artificial solids just nanometers-thin that promise novel optoelectronic functionalities due to the sensitivity of their electronic and optical properties to strong quantum confinement and interfacial interactions. Here, monolayers of n-type MoSe 2 and p-type Mo 1-xW xSe 2–MoSe 2 are grown by vapor transport methods, then transferred and stamped to form artificial vdW heterostructures with different interlayer orientations. Atomic-resolution Z-contrast electron microscopy and electron diffraction are used to characterize both the individual monolayers andmore » the atomic registry between layers in the bilayer vdW heterostructures. These measurements are compared with photoluminescence and low-frequency Raman spectroscopy, which indicates strong interlayer coupling in heterostructures. Remarkably, the heterojunctions exhibit an unprecedented photoconductivity effect that persists at room temperature for several days. This persistent photoconductivity is shown to be tunable by applying a gate bias that equilibrates the charge distribution. Furthermore, these measurements indicate that such ultrathin vdW heterojunctions can function as rewritable optoelectronic switches or memory elements under time-dependent photo-illumination, an effect which appears promising for new monolayer TMDs-based optoelectronic devices applications.« less

Progressive incision of the Channeled Scablands by outburst floods.

PubMed

Larsen, Isaac J; Lamb, Michael P

2016-10-13

The surfaces of Earth and Mars contain large bedrock canyons that were carved by catastrophic outburst floods. Reconstructing the magnitude of these canyon-forming floods is essential for understanding the ways in which floods modify planetary surfaces, the hydrology of early Mars and abrupt changes in climate. Flood discharges are often estimated by assuming that the floods filled the canyons to their brims with water; however, an alternative hypothesis is that canyon morphology adjusts during incision such that bed shear stresses exceed the threshold for erosion by a small amount. Here we show that accounting for erosion thresholds during canyon incision results in near-constant discharges that are five- to ten-fold smaller than full-to-the-brim estimates for Moses Coulee, a canyon in the Channeled Scablands, which was carved during the Pleistocene by the catastrophic Missoula floods in eastern Washington, USA. The predicted discharges are consistent with flow-depth indicators from gravel bars within the canyon. In contrast, under the assumption that floods filled canyons to their brims, a large and monotonic increase in flood discharge is predicted as the canyon was progressively incised, which is at odds with the discharges expected for floods originating from glacial lake outbursts. These findings suggest that flood-carved landscapes in fractured rock might evolve to a threshold state for bedrock erosion, thus implying much lower flood discharges than previously thought.

Surface functionalization of two-dimensional metal chalcogenides by Lewis acid-base chemistry

NASA Astrophysics Data System (ADS)

Lei, Sidong; Wang, Xifan; Li, Bo; Kang, Jiahao; He, Yongmin; George, Antony; Ge, Liehui; Gong, Yongji; Dong, Pei; Jin, Zehua; Brunetto, Gustavo; Chen, Weibing; Lin, Zuan-Tao; Baines, Robert; Galvão, Douglas S.; Lou, Jun; Barrera, Enrique; Banerjee, Kaustav; Vajtai, Robert; Ajayan, Pulickel

2016-05-01

Precise control of the electronic surface states of two-dimensional (2D) materials could improve their versatility and widen their applicability in electronics and sensing. To this end, chemical surface functionalization has been used to adjust the electronic properties of 2D materials. So far, however, chemical functionalization has relied on lattice defects and physisorption methods that inevitably modify the topological characteristics of the atomic layers. Here we make use of the lone pair electrons found in most of 2D metal chalcogenides and report a functionalization method via a Lewis acid-base reaction that does not alter the host structure. Atomic layers of n-type InSe react with Ti4+ to form planar p-type [Ti4+n(InSe)] coordination complexes. Using this strategy, we fabricate planar p-n junctions on 2D InSe with improved rectification and photovoltaic properties, without requiring heterostructure growth procedures or device fabrication processes. We also show that this functionalization approach works with other Lewis acids (such as B3+, Al3+ and Sn4+) and can be applied to other 2D materials (for example MoS2, MoSe2). Finally, we show that it is possible to use Lewis acid-base chemistry as a bridge to connect molecules to 2D atomic layers and fabricate a proof-of-principle dye-sensitized photosensing device.

Low-frequency Raman modes as fingerprints of layer stacking configurations of transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Liang, Liangbo; Puretzky, Alexander; Sumpter, Bobby; Meunier, Vincent; Geohegan, David; David B. Geohegan Team; Vincent Meunier Team

The tunable optoelectronic properties of stacked two-dimensional (2D) crystal monolayers are determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) can be used to determine the exact atomic registration between different layers in few-layer 2D stacks; however, fast and relatively inexpensive optical characterization techniques are essential for rapid development of the field. Using two- and three-layer MoSe2 and WSe2 crystals synthesized by chemical vapor deposition, we show that the generally unexplored low-frequency (LF) Raman modes (<50 cm-1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations [Puretzky and Liang et al, ACS Nano 2015, 9, 6333]. First-principles Raman calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries. Our combined experimental/theoretical work demonstrates the LF Raman modes potentially more effective than HF Raman modes to probe the layer stacking and interlayer interaction for 2D materials. The authors acknowledge support from Eugene P. Wigner Fellowship at the Oak Ridge National Laboratory and the Center for Nanophase Materials Sciences, a DOE Office of Science User Facility.

Interaction and Correlation Effects in Quasi Two-dimensional Materials

NASA Astrophysics Data System (ADS)

Louie, Steven G.

2015-03-01

Experimental and theoretical studies of atomically thin quasi two-dimensional materials (typically related to some parent van der Waals layered crystals) and their nanostructures have revealed that these systems can exhibit highly unusual behaviors. In this talk, we discuss some theoretical studies of the electronic, transport and optical properties of such systems. We present results on graphene and graphene nanostructures as well as other quasi-2D systems such as monolayer and few-layer transition metal dichalcogenides (e.g., MoS2, MoSe2, WS2, and WSe2) and metal monochalcogenides (such as GaSe and FeSe). Owing to their reduced dimensionality, these systems present opportunities for unusual manifestation of concepts and phenomena that may not be so prominent or have not been seen in bulk materials. Symmetry and many-body interaction effects often play a critical role in shaping qualitatively and quantitatively their properties. Several quantum phenomena are discussed, including novel and dominant exciton effects, tunable magnetism, electron supercollimation by disorder, unusual plasmon behaviors, and possible enhanced superconductivity in some of these systems. We investigate their physical origins and compare theoretical predictions with experimental data. This work was supported by DOE under Contract No. DE-AC02-05CH11231 and by NSF under Grant No. DMR10-1006184. I would like to acknowledge collaborations with members of the Louie group and the experimental groups of Crommie, Heinz, Wang, and Zhang.

Observing Imperfection in Atomic Interfaces for van der Waals Heterostructures.

PubMed

Rooney, Aidan P; Kozikov, Aleksey; Rudenko, Alexander N; Prestat, Eric; Hamer, Matthew J; Withers, Freddie; Cao, Yang; Novoselov, Kostya S; Katsnelson, Mikhail I; Gorbachev, Roman; Haigh, Sarah J

2017-09-13

Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities and defects at the interfaces. Here we present the first systematic study of interfaces in van der Waals heterostructure using cross-sectional scanning transmission electron microscope (STEM) imaging. By measuring interlayer separations and comparing these to density functional theory (DFT) calculations we find that pristine interfaces exist between hBN and MoS 2 or WS 2 for stacks prepared by mechanical exfoliation in air. However, for two technologically important transition metal dichalcogenide (TMDC) systems, MoSe 2 and WSe 2 , our measurement of interlayer separations provide the first evidence for impurity species being trapped at buried interfaces with hBN interfaces that are flat at the nanometer length scale. While decreasing the thickness of encapsulated WSe 2 from bulk to monolayer we see a systematic increase in the interlayer separation. We attribute these differences to the thinnest TMDC flakes being flexible and hence able to deform mechanically around a sparse population of protruding interfacial impurities. We show that the air sensitive two-dimensional (2D) crystal NbSe 2 can be fabricated into heterostructures with pristine interfaces by processing in an inert-gas environment. Finally we find that adopting glovebox transfer significantly improves the quality of interfaces for WSe 2 compared to processing in air.

Age and Origin of Eclogite Xenoliths from Navajo Diatremes on the Colorado Plateau

NASA Astrophysics Data System (ADS)

Schulze, D. J.; Malik, L.; Davis, D. W.; Helmstaedt, H. H.

2017-12-01

Six eclogite xenoliths from the Moses Rock and Mule Ear diatremes of the Navajo Volcanic Field on the Colorado Plateau were studied to determine their age(s) and shed light on their origin. Laser ablation inductively-coupled plasma mass spectrometry was used to date zircons in situ by the U-Pb method. In all samples, most of the zircons have low Th/U ratios (<0.1) characteristic of metamorphic zircon and plot on or very near concordia with ages between 27 and 40 Ma, with a few outliers as old as 80 Ma. Some grains with higher Th/U, typically characteristic of magmatic zircon, yield older ages, as old as 1717 ± 25 Ma. In two samples, five zircon yielded data that fall on a discordia between 40 ± 20 and 1717 ± 25 Ma. This suggests that simple derivation from metamorphosed Mesozoic oceanic crust of the shallowly subducted Farallon Plate is not a viable hypothesis for the origin of these eclogites. Instead, the Proterozoic component may indicate that the Farallon Plate also transported material scraped from the overlying Proterozoic mantle during late Mesozoic to Cenozoic subduction. The relationship between the causes of zircon growth in Cenozoic time and the growth of monazite at 28-30 Ma in eclogites of the same suite is unclear, but both may be related to fluxing by water derived from dehydration of serpentinites of the Farallon Plate.

Capsule implosion optimization during the indirect-drive National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landen, O. L.; Edwards, J.; Haan, S. W.

2011-05-15

Capsule performance optimization campaigns will be conducted at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition. The campaigns will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models using a variety of ignition capsule surrogates before proceeding to cryogenic-layered implosions and ignition experiments. The quantitative goals and technique options and down selections for the tuning campaigns are first explained. The computationally derived sensitivities to key laser and target parameters are compared to simple analyticmore » models to gain further insight into the physics of the tuning techniques. The results of the validation of the tuning techniques at the OMEGA facility [J. M. Soures et al., Phys. Plasmas 3, 2108 (1996)] under scaled hohlraum and capsule conditions relevant to the ignition design are shown to meet the required sensitivity and accuracy. A roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget. Finally, we show how the tuning precision will be improved after a number of shots and iterations to meet an acceptable level of residual uncertainty.« less

Substitutional Electron and Hole Doping of WSe2 : Synthesis, Electrical Characterization, and Observation of Band-to-Band Tunneling

NASA Astrophysics Data System (ADS)

Mukherjee, R.; Chuang, H. J.; Koehler, M. R.; Combs, N.; Patchen, A.; Zhou, Z. X.; Mandrus, D.

2017-03-01

Transition-metal dichalcogenides (TMDs) such as MoS2 , MoSe2 , and WSe2 have emerged as promising two-dimensional semiconductors. Many anticipated applications of these materials require both p -type and n -type TMDs with long-term doping stability. Here, we report on the synthesis of substitutionally doped WSe2 crystals using Nb and Re as p - and n -type dopants, respectively. Hall coefficient and gate-dependent transport measurements reveal drastically different doping properties between nominally 0.5% Nb- and 0.5% Re-doped WSe2 . While 0.5% Nb-doped WSe2 (WSe2∶Nb ) is degenerately hole doped with a nearly temperature-independent carrier density of approximately 1019 cm-3 , electrons in 0.5% Re-doped WSe2 (WSe2 ∶Re ) are largely trapped in localized states below the mobility edge and exhibit thermally activated behavior. Charge transport in both WSe2∶Nb and WSe2 ∶Re is found to be limited by Coulomb scattering from ionized impurities. Furthermore, we fabricate vertical van der Waals-junction diodes consisting of multilayers of WSe2∶Nb and WSe2 ∶Re . Finally, we demonstrate reverse rectifying behavior as a direct proof of band-to-band tunneling in our WSe2∶Nb /WSe2∶Re diodes.

nanosheets for gene therapy

NASA Astrophysics Data System (ADS)

Kou, Zhongyang; Wang, Xin; Yuan, Renshun; Chen, Huabin; Zhi, Qiaoming; Gao, Ling; Wang, Bin; Guo, Zhaoji; Xue, Xiaofeng; Cao, Wei; Guo, Liang

2014-10-01

A new class of two-dimensional (2D) nanomaterial, transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2, and WSe2 which have fantastic physical and chemical properties, has drawn tremendous attention in different fields recently. Herein, we for the first time take advantage of the great potential of MoS2 with well-engineered surface as a novel type of 2D nanocarriers for gene delivery and therapy of cancer. In our system, positively charged MoS2-PEG-PEI is synthesized with lipoic acid-modified polyethylene glycol (LA-PEG) and branched polyethylenimine (PEI). The amino end of positively charged nanomaterials can bind to the negatively charged small interfering RNA (siRNA). After detection of physical and chemical characteristics of the nanomaterial, cell toxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Polo-like kinase 1 (PLK1) was investigated as a well-known oncogene, which was a critical regulator of cell cycle transmission at multiple levels. Through knockdown of PLK1 with siRNA carried by novel nanovector, qPCR and Western blot were used to measure the interfering efficiency; apoptosis assay was used to detect the transfection effect of PLK1. All results showed that the novel nanocarrier revealed good biocompatibility, reduced cytotoxicity, as well as high gene-carrying ability without serum interference, thus would have great potential for gene delivery and therapy.

Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials – A general bond polarizability model

PubMed Central

Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Ying Quek, Su

2015-01-01

2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials. PMID:26469313

Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials--A general bond polarizability model.

PubMed

Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Quek, Su Ying

2015-10-15

2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical z(xx)z configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials.

Percolation of spatially constrained Erdős-Rényi networks with degree correlations.

PubMed

Schmeltzer, C; Soriano, J; Sokolov, I M; Rüdiger, S

2014-01-01

Motivated by experiments on activity in neuronal cultures [ J. Soriano, M. Rodríguez Martínez, T. Tlusty and E. Moses Proc. Natl. Acad. Sci. 105 13758 (2008)], we investigate the percolation transition and critical exponents of spatially embedded Erdős-Rényi networks with degree correlations. In our model networks, nodes are randomly distributed in a two-dimensional spatial domain, and the connection probability depends on Euclidian link length by a power law as well as on the degrees of linked nodes. Generally, spatial constraints lead to higher percolation thresholds in the sense that more links are needed to achieve global connectivity. However, degree correlations favor or do not favor percolation depending on the connectivity rules. We employ two construction methods to introduce degree correlations. In the first one, nodes stay homogeneously distributed and are connected via a distance- and degree-dependent probability. We observe that assortativity in the resulting network leads to a decrease of the percolation threshold. In the second construction methods, nodes are first spatially segregated depending on their degree and afterwards connected with a distance-dependent probability. In this segregated model, we find a threshold increase that accompanies the rising assortativity. Additionally, when the network is constructed in a disassortative way, we observe that this property has little effect on the percolation transition.

Interlayer exciton optoelectronics in a 2D heterostructure p–n junction

DOE PAGES

Ross, Jason S.; Rivera, Pasqual; Schaibley, John; ...

2016-12-22

Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p–n junctions in a MoSe 2–WSe 2 heterobilayer. Applying a forward bias enablesmore » the first observation of electroluminescence from interlayer excitons. At zero bias, the p–n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the direct observation of resonant optical excitation of the interlayer exciton. The resulting photocurrent amplitude from the interlayer exciton is about 200 times smaller than the resonant excitation of intralayer exciton. This implies that the interlayer exciton oscillator strength is 2 orders of magnitude smaller than that of the intralayer exciton due to the spatial separation of electron and hole to the opposite layers. Lastly, these results lay the foundation for exploiting the interlayer exciton in future 2D heterostructure optoelectronic devices.« less

Progressive incision of the Channeled Scablands by outburst floods

NASA Astrophysics Data System (ADS)

Larsen, Isaac J.; Lamb, Michael P.

2016-10-01

The surfaces of Earth and Mars contain large bedrock canyons that were carved by catastrophic outburst floods. Reconstructing the magnitude of these canyon-forming floods is essential for understanding the ways in which floods modify planetary surfaces, the hydrology of early Mars and abrupt changes in climate. Flood discharges are often estimated by assuming that the floods filled the canyons to their brims with water; however, an alternative hypothesis is that canyon morphology adjusts during incision such that bed shear stresses exceed the threshold for erosion by a small amount. Here we show that accounting for erosion thresholds during canyon incision results in near-constant discharges that are five- to ten-fold smaller than full-to-the-brim estimates for Moses Coulee, a canyon in the Channeled Scablands, which was carved during the Pleistocene by the catastrophic Missoula floods in eastern Washington, USA. The predicted discharges are consistent with flow-depth indicators from gravel bars within the canyon. In contrast, under the assumption that floods filled canyons to their brims, a large and monotonic increase in flood discharge is predicted as the canyon was progressively incised, which is at odds with the discharges expected for floods originating from glacial lake outbursts. These findings suggest that flood-carved landscapes in fractured rock might evolve to a threshold state for bedrock erosion, thus implying much lower flood discharges than previously thought.

Solar photochemical and thermochemical splitting of water.

PubMed

Rao, C N R; Lingampalli, S R; Dey, Sunita; Roy, Anand

2016-02-28

Artificial photosynthesis to carry out both the oxidation and the reduction of water has emerged to be an exciting area of research. It has been possible to photochemically generate oxygen by using a scheme similar to the Z-scheme, by using suitable catalysts in place of water-oxidation catalyst in the Z-scheme in natural photosynthesis. The best oxidation catalysts are found to be Co and Mn oxides with the e(1) g configuration. The more important aspects investigated pertain to the visible-light-induced generation of hydrogen by using semiconductor heterostructures of the type ZnO/Pt/Cd1-xZnxS and dye-sensitized semiconductors. In the case of heterostructures, good yields of H2 have been obtained. Modifications of the heterostructures, wherein Pt is replaced by NiO, and the oxide is substituted with different anions are discussed. MoS2 and MoSe2 in the 1T form yield high quantities of H2 when sensitized by Eosin Y. Two-step thermochemical splitting of H2O using metal oxide redox pairs provides a strategy to produce H2 and CO. Performance of the Ln0.5A0.5MnO3 (Ln = rare earth ion, A = Ca, Sr) family of perovskites is found to be promising in this context. The best results to date are found with Y0.5Sr0.5MnO3. © 2016 The Author(s).

Sensitivity Enhancement of Transition Metal Dichalcogenides/Silicon Nanostructure-based Surface Plasmon Resonance Biosensor

PubMed Central

Ouyang, Qingling; Zeng, Shuwen; Jiang, Li; Hong, Liying; Xu, Gaixia; Dinh, Xuan-Quyen; Qian, Jun; He, Sailing; Qu, Junle; Coquet, Philippe; Yong, Ken-Tye

2016-01-01

In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS2/MoSe2/WS2/WSe2 (defined as MX2) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX2 layers are presented respectively. The results show that silicon nanosheet and MX2 layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX2 enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS2. PMID:27305974

Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

NASA Astrophysics Data System (ADS)

Hohenberger, M.; Albert, F.; Palmer, N. E.; Lee, J. J.; Döppner, T.; Divol, L.; Dewald, E. L.; Bachmann, B.; MacPhee, A. G.; LaCaille, G.; Bradley, D. K.; Stoeckl, C.

2014-11-01

In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic-a multichannel, hard x-ray spectrometer operating in the 20-500 keV range-has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ˜300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U Kβ). The detectors impulse response function was measured in situ on NIF short-pulse (˜90 ps) experiments, and in off-line tests.

Magnetic Helicity Injection and Thermal Transport

NASA Astrophysics Data System (ADS)

Moses, Ronald; Gerwin, Richard; Schoenberg, Kurt

1999-11-01

In magnetic helicity injection, a current is driven between electrodes, parallel to the magnetic field in the edge plasma of a machine.^1 Plasma instabilities distribute current throughout the plasma. To model the injection of magnetic helicity, K, into an arbitrary closed surface, K is defined as the volume integral of A^.B. To make K unique, a gauge is chosen where the tangential surface components of A are purely solenoidal. If magnetic fields within a plasma are time varying, yet undergo no macroscopic changes over an extended period, and if the plasma is subject to an Ohm’s law with Hall terms, then it is shown that no closed magnetic surfaces with sustained internal currents can exist continuously within the plasma.^2 It is also shown that parallel thermal transport connects all parts of the plasma to the helicity injection electrodes and requires the electrode voltage difference to be at least 2.5 to 3 times the peak plasma temperature. This ratio is almost independent of the length of the electron mean-free path. If magnetic helicity injection is to be used for fusion-grade plasmas, then high-voltage, high-impedance injection techniques must be developed. ^1T. R. Jarboe, Plasma Physics and Controlled Fusion, V36, 945-990 (June 1994). ^2R. W. Moses, 1991 Sherwood International Fusion Theory Conference, Seattle, WA (April 22-24, 1991).

KSC-2009-6403

NASA Image and Video Library

2009-11-16

CAPE CANAVERAL, Fla. - Media representatives and Twitter followers participate in a post-launch news conference in the NASA Press Site auditorium at NASA's Kennedy Space Center in Florida after the successful launch of space shuttle Atlantis. On the dais, from left, are Public Affairs moderator Mike Curie; Bill Gerstenmaier, associate administrator for Space Operations; Mike Moses, chair, Mission Management Team; and Mike Leinbach, space shuttle launch director. Liftoff of Atlantis on its STS-129 mission came at 2:28 p.m. EST Nov. 16 from Launch Pad 39A. Aboard are crew members Commander Charles O. Hobaugh; Pilot Barry E. Wilmore; and Mission Specialists Leland Melvin, Randy Bresnik, Mike Foreman and Robert L. Satcher Jr. On STS-129, the crew will deliver two ExPRESS Logistics Carriers to the International Space Station, the largest of the shuttle's cargo carriers, containing 15 spare pieces of equipment including two gyroscopes, two nitrogen tank assemblies, two pump modules, an ammonia tank assembly and a spare latching end effector for the station's robotic arm. Atlantis will return to Earth a station crew member, Nicole Stott, who has spent more than two months aboard the orbiting laboratory. STS-129 is slated to be the final space shuttle Expedition crew rotation flight. For information on the STS-129 mission and crew, visit http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts129/index.html. Photo credit: NASA/Kim Shiflett

[Philoctetes--a theme with variations].

PubMed

Thomasen, A L

1983-01-01

The legend of Philoctetes and his snake bite is found in so many versions seen from the most differing aspects, that each new attempt to throw light on this throng of literary and artistic interpretations must be based on the author's personal choice of and attitude to the almost limitless material. Since the time of Homer the legend has spread from ancient Greece across Europe, all the way to the utmost northern base of our culture; very early the tradition of the famous archer of the Trojan war was known and written down in Iceland. The author of the present essay has stressed the psychological interpretations of the legend as seen in the great Greek tragedies and in painting and sculpture, especially from the point of view of medical history. Furthermore the interplay of art and medicine in the Philoctetes legend has inspired the author to a closer examination of the role in the fate of mankind played by the snake from the beginning of time, seen in a religious as well as a secular context. For heathens as well as Christians the snake could bring fortune or calamity. Sometimes a vile demon, it brought harm; but the copper snake of Moses in the desert and the snake in the service of Asclepios protected and healed mankind. This creature so full of contrary powers and intentions almost became a mirror to the complex nature and unpredictable fate of man.

Survivorship of adult Aedes albopictus (Diptera: Culicidae) feeding on indoor ornamental plants with no inflorescence.

PubMed

Qualls, Whitney A; Xue, Rui De; Beier, John C; Müller, Günter C

2013-06-01

The international trade of lucky bamboo (Dracaena sanderiana [Asparagaceae]) is responsible for certain introductions of the exotic species Aedes albopictus (Skuse) in California and the Netherlands. Understanding the association of this species with lucky bamboo and other ornamental plants is important from a public health standpoint. The aim of this study was to investigate the importance of indoor ornamental plants as sugar sources for adult A. albopictus. If exposed to D. sanderiana, bromeliad (Guzmania spp. hybrid [Bromeliaceae]), Moses-in-the-cradle (Rhoeo spathacea [Commelinaceae]), 10 % sucrose solution, and a negative water control as the only nutrient source, adult female A. albopictus mean survival time was 12, 7, 6, 15, and 4 days, respectively. Mean survival times for adult males were not significantly different (P > 0.05) from the females and were 10, 7, 6, 14, and 3 days, respectively. Combined male and female survival times were not significantly different on lucky bamboo compared to survival times on a 10 % sucrose control. Based on our findings, A. albopictus can readily survive long enough to complete a gonotrophic cycle and potentially complete the extrinsic incubation period for many arboviruses when only provided access to lucky bamboo plants or possibly other common ornamentals. Vector control professionals should be aware of potential in-home infestations and public health concerns associated with mosquito breeding and plant tissue feeding on ornamental plants.

Water-level altitudes 2016 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973–2015 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Ramage, Jason K.; Johnson, Michaela R.

2016-10-07

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains regional-scale maps depicting approximate 2016 water-level altitudes (represented by measurements made during December 2015–March 2016) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2015–16) water-level changes for each aquifer; maps depicting approximate contoured 5-year (2011–16) water-level changes for each aquifer; maps depicting approximate contoured long-term (1990–2016 and 1977–2016) water-level changes for the Chicot and Evangeline aquifers; a map depicting approximate contoured long-term (2000–16) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured long-term cumulative compaction of subsurface sediments at the extensometers during 1973–2015. Tables listing the water-level data used to construct each water-level map for each aquifer and the measured long-term cumulative compaction data for each extensometer site are included. Graphs depicting water-level measurement data also are included; these graphs can be used to approximate changes in effective stress caused by changes in groundwater withdrawal from the Chicot and Evangeline aquifers.In 2016, water-level-altitude contours for the Chicot aquifer ranged from 200 feet (ft) below the vertical datum (North American Vertical Datum of 1988; hereinafter, datum) in a localized area in northwestern Harris County to 200 ft above datum in west-central Montgomery County. Water-level changes during 2015–16 in the Chicot aquifer ranged from a 39-ft decline to a 26-ft rise. Contoured 5-year and long-term changes in water-level altitudes of the Chicot aquifer ranged from a 30-ft decline to a 20-ft rise (2011–16), from a 140-ft decline to a 160-ft rise (1990–2016), and from a 120-ft decline to a 200-ft rise (1977–2016). In 2016, water-level-altitude contours for the Evangeline aquifer ranged from 250 ft below datum in three separate areas in south-central Montgomery County and extending into north-central Harris County, in west-central Harris County, and in southwestern Harris County to 200 ft above datum in southeastern Grimes and northwestern Montgomery Counties. Water-level changes during 2015–16 in the Evangeline aquifer ranged from a 65-ft decline to a 61-ft rise. Contoured 5-year and long-term changes in water-level altitudes of the Evangeline aquifer ranged from a 60-ft decline to a 40-ft rise (2011–16), from a 160-ft decline to a 160-ft rise (1990–2016), and from a 320-ft decline to a 240-ft rise (1977–2016). In 2016, water-level-altitude contours for the Jasper aquifer ranged from 200 ft below datum in south-central Montgomery County extending into north-central Harris County to 250 ft above datum in northwestern Montgomery County and extending into eastern Grimes County and southwestern Walker County. Water-level changes during 2015–16 in the Jasper aquifer ranged from a 38-ft decline to a 51-ft rise. Contoured 5-year and long-term changes in water-level altitudes of the Jasper aquifer ranged from a 60-ft decline to a 40-ft rise (2011–16) and from a 220-ft decline to a 20-ft decline (2000–16).Compaction of subsurface sediments (mostly in the fine-grained silt and clay layers) in the Chicot and Evangeline aquifers was recorded continuously by using 13 extensometers at 11 sites that were either activated or installed between 1973 and 1980. During the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2015, measured cumulative compaction at the 13 extensometers ranged from 0.095 ft at the Texas City-Moses Lake extensometer to 3.666 ft at the Addicks extensometer. From January through December 2015, the Northeast, Southwest, Addicks, Johnson Space Center, and Clear Lake (deep) extensometers recorded net decreases in land-surface elevation, but the Lake Houston, East End, Texas City-Moses Lake, Baytown C–1 (shallow), Baytown C–2 (deep), Seabrook, Clear Lake (shallow), and Pasadena extensometers recorded net increases in land-surface elevation. For the 11 extensometer sites during the selected years 1988, 1998, 2008, 2012, and 2015, the smallest effective stress (20.12 pounds per square inch [psi]) was estimated at the Texas City-Moses Lake extensometer site and was produced by a measured water level of 46.42 ft below land-surface datum (blsd) in January 2008. The corresponding net compaction during 2007 at this site was 0.001 ft. The largest effective stress (174.86 psi) was estimated at the Addicks extensometer site and was produced by a measured water level of 403.38 ft blsd in January 1998. The corresponding net compaction at the Addicks site was 0.067 ft in 1997.The 2011 drought caused water-level declines in the aquifers that were documented by the water-level-measurement data collected in January 2012. During the 2011 drought, the 13 extensometers recorded varying amounts of compaction that ranged from a net compaction value of 0.002 ft recorded by the Texas City-Moses Lake extensometer to a net compaction value of 0.192 ft recorded by the Pasadena extensometer. Water-level data for 1988, 1998, 2008, 2012, and 2015 and the corresponding net compaction values recorded by the extensometers for 1987, 1997, 2007, 2011, and 2014 were used to illustrate the cause and effect relations between changes in water level caused by groundwater withdrawals and resulting changes in effective stress. Changes in effective stress are related to changes in land-surface elevations caused by compaction of the fine-grained sediments composing the Chicot and Evangeline aquifers.The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site; differences among sites in the ratios of sand, silt, and clay and their corresponding compressibilities; and previously established preconsolidation heads. It is not appropriate, therefore, to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction recorded by proximal extensometers.

Layer Control of WSe2 via Selective Surface Layer Oxidation.

PubMed

Li, Zhen; Yang, Sisi; Dhall, Rohan; Kosmowska, Ewa; Shi, Haotian; Chatzakis, Ioannis; Cronin, Stephen B

2016-07-26

We report Raman and photoluminescence spectra of mono- and few-layer WSe2 and MoSe2 taken before and after exposure to a remote oxygen plasma. For bilayer and trilayer WSe2, we observe an increase in the photoluminescence intensity and a blue shift of the photoluminescence peak positions after oxygen plasma treatment. The photoluminescence spectra of trilayer WSe2 exhibit features of a bilayer after oxygen plasma treatment. Bilayer WSe2 exhibits features of a monolayer, and the photoluminescence of monolayer WSe2 is completely absent after the oxygen plasma treatment. These changes are observed consistently in more than 20 flakes. The mechanism of the changes observed in the photoluminescence spectra of WSe2 is due to the selective oxidation of the topmost layer. As a result, N-layer WSe2 is reduced to N-1 layers. Raman spectra and AFM images taken from the WSe2 flakes before and after the oxygen treatment corroborate these findings. Because of the low kinetic energy of the oxygen radicals in the remote oxygen plasma, the oxidation is self-limiting. By varying the process duration from 1 to 10 min, we confirmed that the oxidation will only affect the topmost layer of the WSe2 flakes. X-ray photoelectron spectroscopy shows that the surface layer WOx of the sample can be removed by a quick dip in KOH solution. Therefore, this technique provides a promising way of controlling the thickness of WSe2 layer by layer.

Novel measurement of rapid treatment success with ReQuest: first and sustained symptom relief as outcome parameters in patients with endoscopy-negative GERD receiving 20 mg pantoprazole or 20 mg esomeprazole.

PubMed

Mönnikes, Hubert; Pfaffenberger, Bernd; Gatz, Gudrun; Hein, Jasper; Bardhan, Karna Dev

2007-01-01

A prime concern for gastroesophageal reflux disease (GERD) patients is fast symptom control. Sparse valid information is available on the rapidity of the effect of proton pump inhibitors in providing symptom relief. The new reflux questionnaire ReQuest is validated for daily assessment of changes in GERD symptoms. Therefore, this study investigated the efficacy of 20 mg pantoprazole and 20 mg esomeprazole with regard to the time to symptom relief in patients with endoscopy-negative GERD (enGERD) using ReQuest. 529 patients were treated with pantoprazole or esomeprazole over 4 weeks. ReQuest symptom scores were assessed daily. The mean and median times to first and sustained symptom relief were determined. Median time to first symptom relief was 2 days for both drugs (intention-to-treat population). The median time to sustained symptom relief was 3 days shorter with pantoprazole (10.0 vs. 13.0 days). The Hodges-Lehmann estimator for the difference in time to reach first and sustained symptom relief between both groups was 0.00 days. For both variables the one-sided 95% CI (Moses) was [0.00; infinity[, documenting no significant differences between the treatment groups. The rapidity of symptom control can be evaluated by clinically significant parameters using ReQuest. Pantoprazole and esomeprazole are equally effective in the time to first and sustained symptom relief. Copyright 2007 S. Karger AG, Basel.

Geologic map of southwestern Sequoia National Park, Tulare County, California

USGS Publications Warehouse

Sisson, Thomas W.; Moore, James G.

2013-01-01

This map shows the geology of 675 km2 (260 mi2) on the west slope of the Sierra Nevada, California, mainly in Sequoia National Park and Sequoia National Forest. It was produced by the U.S. Geological Survey (USGS) at the request of the National Park Service to complete the geologic map coverage of Kings Canyon and Sequoia National Parks. The area includes the Mineral King 15’ topographic quadrangle (sheet 1) and strips along the east and northeast edges of the Kaweah 15’ topographic quadrangle (sheet 2), both in Tulare County. Mapping was performed mainly on the 1:24,000-scale Mineral King, Silver City, Quinn Peak, Moses Mountain, Case Mountain, and Dennison Peak 7.5’ topographic quadrangle bases. Rocks within the study area are chiefly Cretaceous granites and granodiorites of the Sierra Nevada batholith that intruded coherent masses of Mesozoic metasedimentary and metavolcanic rocks. Quaternary till and talus are the principal surficial deposits, with the exception of a large bouldery alluvial apron near the southwest corner of the map area. The study area includes the headwaters of the Kaweah River (East and South Forks), Tule River (North Fork and North Fork of the Middle Fork), and the Little Kern River. Relief is considerable, with elevations spanning from 1,500 feet along the Middle Fork Kaweah River to 12,432 feet at the summit of Florence Peak along the crest of the Great Western Divide.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Shang-Min; Grosheintz, Luc; Kitzmann, Daniel

We present an open-source and validated chemical kinetics code for studying hot exoplanetary atmospheres, which we name VULCAN. It is constructed for gaseous chemistry from 500 to 2500 K, using a reduced C–H–O chemical network with about 300 reactions. It uses eddy diffusion to mimic atmospheric dynamics and excludes photochemistry. We have provided a full description of the rate coefficients and thermodynamic data used. We validate VULCAN by reproducing chemical equilibrium and by comparing its output versus the disequilibrium-chemistry calculations of Moses et al. and Rimmer and Helling. It reproduces the models of HD 189733b and HD 209458b by Mosesmore » et al., which employ a network with nearly 1600 reactions. We also use VULCAN to examine the theoretical trends produced when the temperature–pressure profile and carbon-to-oxygen ratio are varied. Assisted by a sensitivity test designed to identify the key reactions responsible for producing a specific molecule, we revisit the quenching approximation and find that it is accurate for methane but breaks down for acetylene, because the disequilibrium abundance of acetylene is not directly determined by transport-induced quenching, but is rather indirectly controlled by the disequilibrium abundance of methane. Therefore we suggest that the quenching approximation should be used with caution and must always be checked against a chemical kinetics calculation. A one-dimensional model atmosphere with 100 layers, computed using VULCAN, typically takes several minutes to complete. VULCAN is part of the Exoclimes Simulation Platform (ESP; exoclime.net) and publicly available at https://github.com/exoclime/VULCAN.« less

Novel exciton systems in 2D TMD monolayers and heterobilayers

NASA Astrophysics Data System (ADS)

Yu, Hongyi

In this talk, two exciton systems in transition metal dichalcogenides (TMDs) monolayer and heterobilayer will be discussed. In TMD monolayers, the strong e-h Coulomb exchange interaction splits the exciton and trion dispersions into two branches with zero and finite gap, respectively. Each branch is a center-of-mass wave vector dependent coherent superposition of the two valleys, which leads to a valley-orbit coupling and possibly a trion valley Hall effect. The exchange interaction also eliminates the linear polarization of the negative trion PL emission. In TMD heterobilayers with a type-II band alignment, the low energy exciton has an interlayer configuration with the e and h localized in opposite layers. Because of the inevitable twist or/and lattice mismatch between the two layers, the bright interlayer excitons are located at finite center-of-mass velocities with a six-fold degeneracy. The corresponding photon emission is elliptically polarized, with the major axis locked to the direction of exciton velocity, and helicity determined by the valley indices of the e and h. Some experimental results on the interlayer excitons in the WSe2-MoSe2 heterobilayers will also be presented. The interlayer exciton exhibits a long lifetime as well as a long depolarization time, which facilitate the observation of a PL polarization ring pattern due to the valley dependent exciton-exciton interaction induced expansion. The works were supported by the Research Grant Council of Hong Kong (HKU17305914P, HKU705513P), the Croucher Foundation, and the HKU OYRA and ROP.

Combining MEDLINE and publisher data to create parallel corpora for the automatic translation of biomedical text

PubMed Central

2013-01-01

Background Most of the institutional and research information in the biomedical domain is available in the form of English text. Even in countries where English is an official language, such as the United States, language can be a barrier for accessing biomedical information for non-native speakers. Recent progress in machine translation suggests that this technique could help make English texts accessible to speakers of other languages. However, the lack of adequate specialized corpora needed to train statistical models currently limits the quality of automatic translations in the biomedical domain. Results We show how a large-sized parallel corpus can automatically be obtained for the biomedical domain, using the MEDLINE database. The corpus generated in this work comprises article titles obtained from MEDLINE and abstract text automatically retrieved from journal websites, which substantially extends the corpora used in previous work. After assessing the quality of the corpus for two language pairs (English/French and English/Spanish) we use the Moses package to train a statistical machine translation model that outperforms previous models for automatic translation of biomedical text. Conclusions We have built translation data sets in the biomedical domain that can easily be extended to other languages available in MEDLINE. These sets can successfully be applied to train statistical machine translation models. While further progress should be made by incorporating out-of-domain corpora and domain-specific lexicons, we believe that this work improves the automatic translation of biomedical texts. PMID:23631733