Long-term stability studies of a semiconductor photoelectrode in three-electrode configuration

Improving the stability of semiconductor materials is one of the major challenges for sustainable and economic photoelectrochemical water splitting. N-terminated GaN nanostructures have emerged as a practical protective layer for conventional high efficiency but unstable Si and III-V photoelectrodes due to their near-perfect conduction band-alignment, which enables efficient extraction of photo-generated electrons, and N-terminated surfaces, which protects against chemical and photo-corrosion. Here, we demonstrate that Pt-decorated GaN nanostructures on an n+-p Si photocathode can exhibit an ultrahigh stability of 3000 h (i.e., over 500 days for usable sunlight ∼5.5 h per day) at a large photocurrent density (>35 mA cm-2) in three-electrode configuration under AM 1.5G one-sun illumination. The measured applied bias photon-to-current efficiency of 11.9%, with an excellent onset potential of ∼0.56 V vs. RHE, is one of the highest values reported for a Si photocathode under AM 1.5G one-sun illumination. This study provides a paradigm shift for the design and development of semiconductor photoelectrodes for PEC water splitting: stability is no longer limited by the light absorber, but rather by co-catalyst particles

Neutrino masses and μ\mu terms in a supersymmetric extra U(1) model

We propose a supersymmetric extra U(1) model, which can generate small neutrino masses and necessary $\mu$ terms, simultaneously. Fields including quarks and leptons are embedded in three ${\bf 27}$s of $E_6$ in a different way among generations. The model has an extra U(1) gauge symmetry at TeV regions, which has discriminating features from other models studied previously. Since a neutrino mass matrix induced in the model has a constrained texture with limited parameters, it can give a prediction. If we impose neutrino oscillation data to fix those parameters, a value of $\sin\theta_{13}$ can be determined. We also discuss several phenomenological features which are discriminated from the ones of the MSSM.Comment: 27 pages, 2 figures, final version for publicatio

The OmegaWhite Survey for Short-Period Variable Stars IV: Discovery of the warm DQ white dwarf OW J175358.85-310728.9

We present the discovery and follow-up observations of the second known variable warm DQ white dwarf OW J175358.85-310728.9 (OW J1753-3107). OW J1753-3107 is the brightest of any of the currently known warm or hot DQ and was discovered in the OmegaWhite Survey as exhibiting optical variations on a period of 35.5452 (2) mins, with no evidence for other periods in its light curves. This period has remained constant over the last two years and a single-period sinusoidal model provides a good fit for all follow-up light curves. The spectrum consists of a very blue continuum with strong absorption lines of neutral and ionised carbon, a broad He I 4471 A line, and possibly weaker hydrogen lines. The C I lines are Zeeman split, and indicate the presence of a strong magnetic field. Using spectral Paschen-Back model descriptions, we determine that OW J1753-3107 exhibits the following physical parameters: T_eff = 15430 K, log(g) = 9.0, log(N(C)/N(He)) = -1.2, and the mean magnetic field strength is B_z =2.1 MG. This relatively low temperature and carbon abundance (compared to the expected properties of hot DQs) is similar to that seen in the other warm DQ SDSS J1036+6522. Although OW J1753-3107 appears to be a twin of SDSS J1036+6522, it exhibits a modulation on a period slightly longer than the dominant period in SDSS J1036+6522 and has a higher carbon abundance. The source of variations is uncertain, but they are believed to originate from the rotation of the magnetic white dwarf.Comment: 11 pages, 8 figures, 7 tables. Accepted for publication by MNRA

School Finance Reform: Do Equalized Expenditures Imply Equalized Teacher Salaries?

This is the publisher's version, also available electronically from "http://www.mitpressjournals.org".Kentucky is a poor, relatively rural state that contrasts greatly with the relatively urban and wealthy states typically the subject of education studies employing large-scale administrative data. For this reason, Kentucky's experience of major school finance and curricular reform is highly salient for understanding teacher labor market dynamics. This study examines the time path of teacher salaries in Appalachian and non-Appalachian Kentucky using a novel teacher-level administrative data set. Our results suggest that the Kentucky Education Reform Act (KERA) provided a salary boost for all Appalachian teachers, resulting in a wage premium for teachers of low and medium experience and equalizing pay across Appalachian and non-Appalachian districts for teachers of high experience. However, we find that Appalachian salaries fell back to the level of non-Appalachian teachers roughly a decade following reform, at which point the pre-KERA remuneration patterns re-emerge

Esophageal surgery – the experience of the department of surgery of CME faculty of SUMPh “Nicolae Testemitanu”

Catedra chirurgie FECMF, USMF „Nicolae Testemiţanu”, Chişinău, Republica Moldova, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Esofagul, pentru chirurgi, rămâne un segment deosebit al tractului digestiv atât din cauza particularităţilor anatomo-topografice a organului, a căilor de acces către acesta, cât şi a tehnicilor operatorii asupra respectivului. Scopul lucrării: De a ne împărtăşi cu experienţa Clinicii de 30 ani în domeniul chirurgiei esofagiene. Material şi metode: Clinica de Chirurgie FECMF a USMF „Nicolae Testemiţanu” – secţia de chirurgie toracică şi chirurgie generală a Spitalului Clinic Republican îşi are direcţia cercetărilor, studiilor practico-ştiinţifice ale intervenţiilor pe esofag din 1974. Fişierul clinicii deţine mai mult de 1000 operaţii pe esofag. Rezultate: Punct de pornire au servit traumele esofagului adunând 70 cazuri. Alți 83 pacienţi – operaţi pentru diverticul, 192 cu hernii a hiatusului esofagian, 226 suferinzi de diferite forme de stenoze postcaustice, 118 pacienţi s -au operat pentru boala de reflux gastroesofagian, 115 cu achalazii, cu neoplasm esofagian s-au operat 92 pacienţi, esofag Barrett au avut 34 bolnavi, neoplasm al joncţiunii esofago-gastrice – 37 pacienţi. Avem 32 cazuri cu ruptură spontană de esofag (sindromul Boerhaave). Concluzii: Aceasta este experienţa Clinicii, în baza căreia s-a susţinut o teză de doctor habilitat şi două teze de doctor în medicină.Introduction: Esophageal surgery represents very special kind of digestive surgery, because of multiple factors – anatomical-topographic features, specific surgical access and surgical technique. Aim: To evaluate our clinical experience of 30 years of esophageal surgery. Material and methods: Since 1974, in the Department of Surgery of CME Faculty of SUMPh „Nicolae Testemitanu”, thoracic and general surgery departments of Republican Clinical Hospital, were performed about 1000 clinical cases of esophageal surgery. Results: Our first experience in esophageal surgery, as a start point was esophageal injuries – 70 patients, followed by esophageal diverticula – 83 patients, esophageal hiatus hernia – 192 treatment cases, esophageal stricture of various origin – 226 cases, 118 patients have been treated for gastro-esophageal reflux disease, 115 cases with achalasia of esophagus, 92 patients have been treated for esophageal cancer, 34 cases – with Barrett’s esophagus, gastroesophageal junction cancer – 37 cases. In addition, we have experience of 32 cases of spontaneous esophagus rupture (Boerhaave syndrome). Conclusions: The experience of the Clinic mentioned above was reflected in a thesis of doctor habilitatus of medical since and two thesis of doctor of medical since

Effect of cuscuta reflexa stem and calotropis procera leaf extracts on glucose tolerance in glucose-induced hyperglycemic rats and mice

Cuscuta reflexa (whole plant) and Calotropis procera (leaves) are used in folk medicine of Bangladesh to control blood sugar in patients suffering from diabetes mellitus. The hypoglycemic effects of methanol and chloroform extracts of whole plants of Cuscuta reflexa, and methanol extract of leaves of Calotropis procera were investigated in oral glucose tolerance tests in Long Evans rats and Swiss albino mice, respectively. Both methanol and chloroform extracts of Cuscuta reflexa whole plant demonstrated significant oral hypoglycemic activity in glucose-loaded rats at doses of 50, 100 and 200 mg/kg body weight. The methanol extract of leaves of Calotropis procera, when tested at doses of 100 and 250 mg/kg body weight did not demonstrate any oral hypoglycemic effect when tested in glucose-loaded mice.Key words: Cuscuta reflexa, Calotropis procera, hypoglycemic activity, oral glucose tolerance test

On the construction of model Hamiltonians for adiabatic quantum computation and its application to finding low energy conformations of lattice protein models

In this report, we explore the use of a quantum optimization algorithm for obtaining low energy conformations of protein models. We discuss mappings between protein models and optimization variables, which are in turn mapped to a system of coupled quantum bits. General strategies are given for constructing Hamiltonians to be used to solve optimization problems of physical/chemical/biological interest via quantum computation by adiabatic evolution. As an example, we implement the Hamiltonian corresponding to the Hydrophobic-Polar (HP) model for protein folding. Furthermore, we present an approach to reduce the resulting Hamiltonian to two-body terms gearing towards an experimental realization.Comment: 35 pages, 8 figure

Explosions of water clusters in intense laser fields

Energetic, highly-charged oxygen ions, $O^{q+}$ ($q\leq 6$), are copiously produced upon laser field-induced disassembly of highly-charged water clusters, $(H_2O)_n$ and $(D_2O)_n$, $n\sim$ 60, that are formed by seeding high-pressure helium or argon with water vapor. $Ar_n$ clusters (n$\sim$40000) formed under similar experimental conditions are found undergo disassembly in the Coulomb explosion regime, with the energies of $Ar^{q+}$ ions showing a $q^2$ dependence. Water clusters, which are argued to be considerably smaller in size, should also disassemble in the same regime, but the energies of fragment O$^{q+}$ ions are found to depend linearly on $q$ which, according to prevailing wisdom, ought to be a signature of hydrodynamic expansion that is expected of much larger clusters. The implication of these observations on our understanding of the two cluster explosion regimes, Coulomb explosion and hydrodynamic expansion, is discussed. Our results indicate that charge state dependences of ion energy do not constitute an unambiguous experimental signature of cluster explosion regime.Comment: Submitted to Phys. Rev.

Novel Plasmonic Nanocavities for Optical Trapping-Assisted Biosensing Applications

Plasmonic nanocavities have proved to confine electromagnetic fields into deep subwavelength volumes, implying their potentials for enhanced optical trapping and sensing of nanoparticles. In this review, the fundamentals and performances of various plasmonic nanocavity geometries are explored with specific emphasis on trapping and detection of small molecules and single nanoparticles. These applications capitalize on the local field intensity, which in turn depends on the size of plasmonic nanocavities. Indeed, properly designed structures provide significant local field intensity and deep trapping potential, leading to manipulation of nano-objects with low laser power. The relationship between optical trapping-induced resonance shift and potential energy of plasmonic nanocavity can be analytically expressed in terms of the intercavity field intensity. Within this framework, recent experimental works on trapping and sensing of single nanoparticles and small molecules with plasmonic nanotweezers are discussed. Furthermore, significant consideration is given to conjugation of optical tweezers with Raman spectroscopy, with the aim of developing innovative biosensors. These devices, which take the advantages of plasmonic nanocavities, will be capable of trapping and detecting nanoparticles at the single molecule level

POET: POlarimeters for Energetic Transients

POET (Polarimeters for Energetic Transients) is a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2-15 keV and a high energy polarimeter (Gamma-Ray Polarimeter Experiment -- GRAPE) that will measure polarization in the 60-500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The POET spacecraft provides a zenith-pointed platform for maximizing the exposure to deep space. Spacecraft rotation will provide a means of effectively dealing with systematics in the polarization response. POET will provide sufficient sensitivity and sky coverage to measure statistically significant polarization for up to 100 GRBs in a two-year mission. Polarization data will also be obtained for solar flares, pulsars and other sources of astronomical interest