Specific heat study of the Na(0.3)CoO(2).1.3H(2)O superconductor: influence of the complex chemistry

We report results of specific heat measurements on polycrystalline samples of the layered superconductor, Na(0.3)CoO(2).1.3H(2)O. The electronic contribution to the specific heat, gamma, is found to be 12.2 mJ/mol-K2. The feature at the superconducting transition is rather sharp, becoming broad and strongly suppressed in an applied magnetic field. The data indicate a residual normal state electronic specific heat at low temperatures, implying that there is a sizable population of normal state electrons in the samples even below Tc. Inhomogeneity in the Na content, to which the superconducting state is exquisitely sensitive, appears to be the most likely explanation for these results. These results further indicate that special sample handling is required for an accurate characterization of the superconducting state in this material.Comment: publication information adde

Nature of Correlated Motion of Electrons in the Parent Cobaltate Superconductors

Recently discovered class of cobaltate superconductors (Na0.3CoO2.nH2O) is a novel realization of interacting quantum electron systems in a triangular network with low-energy degrees of freedom. We employ angle-resolved photoemission spectroscopy to uncover the nature of microscopic electron motion in the parent superconductors for the first time. Results reveal a large hole-like Fermi surface (consistent with Luttinger theorem) generated by the crossing of super-heavy quasiparticles. The measured quasiparticle parameters collectively suggest a two orders of magnitude departure from the conventional Bardeen-Cooper-Schrieffer electron dynamics paradigm and unveils cobaltates as a rather hidden class of relatively high temperature superconductors.Comment: 5 pages, 4 figures, 1 tabl

Chemical Instability of the Cobalt Oxyhydrate Superconductor under Ambient Conditions

The layered sodium cobalt oxyhydrate superconductor Na0.3CoO2*1.4H2O is shown through X-ray diffraction and thermogravimetric studies to be one of a series of hydrated phases of Na0.3CoO2. Further, it is shown that the material is exceptionally sensitive to both temperature and humidity near ambient conditions, easily dehydrating to a non-superconducting lower hydrate. The observation of this stable lower hydrate with c=13.8 angstroms implies that the superconductivity turns on in this system between CoO2 layer spacings of 6.9 and 9.9 angstroms at nominally constant chemical doping.Comment: 10 pages and 4 figure

A comparative study of FLL and PLL in boost PFC converter control for smart greenhouse farming application

LED lights have become very popular recently for smart farming applications, where they provide artificial light as the substitute for sunlight in a greenhouse or indoor farming environment. To ensure a low total operational cost and improve the efficiency of farming in those environments, it is imperative that the overall LED lighting system is energy efficient. LED is a dc system, whereas the grid is an ac system. As such, an LED driver is needed to perform the necessary voltage conversion. The boost power factor correction (PFC) converter is a popular LED driver that provides output voltage regulation and power factor correction at the same time. As the LED driver is grid-connected, its control system requires real-time estimation of the grid voltage parameter information for reference current generation. In this study, a comparison between frequency-and phase-locked loops as the grid detection method inside the converter control system is provided. For the phase-locked loop (PLL), a single-phase quasi-type-1 structure is considered. It is then compared with the conventional second-order generalised integrator (SOGI)frequency-locked loop (FLL). Comprehensive numerical studies are performed to evaluate the performance of FLL and PLL in challenging grid voltage cases. Results show that the source current has a lower total harmonic distortion when PLL is used as the synchronisation tool over the FLL counterpart. This can be attributed to the use of moving average filter in the PLL, which provides additional harmonic robustness compared to FLL. Lower distortion by the PLL method will the make LED driver, consequently smart farming more energy efficient

Thermoelectrics Near the Mott Localization-Delocalization Transition

We give an overview on current status of the theoretical research on Thermoelectricity for correlated materials. We derive the theoretical formulas which become exact at low and high temperature and discuss the intermediate temperature results. In particular, we show that within Dynamical Mean Field Theory the low temperature sign of the thermopower is not necessary the same as in LDA, and that significant non-universality is expected due to strong correlations.Comment: appeared in "Properties and Applications of Thermoelectric Materials", Edited by V. Zlatic and A.C. Hewson, Springe

PROCESS MODELLING AND DEBOTTLENECKING STUDY OF A VACCINE PRODUCTION

ABSTRACT: The main objective of this research work was to model and optimise the production of a locally-developed Infectious Coryza (IC) vaccine. The simulation work was performed using a commercially available batch process simulator SuperPro Designer v5.5. Six debottlenecking schemes were analysed using throughput analysis and cost to benefit ratio (CBR) when the annual production was set to increase by 100%. Based on the economic analysis, the selected debottlenecking scheme has an annual predicted revenue of USD 240 million, with a gross margin of 9.13% and a return on investment (ROI) of 46.12%. In addition, the payback period of the selected scheme is estimated to be within three years.  ABSTRAK: Objektif utama dalam penyelidikan ini adalah untuk memodelkan dan mengoptimumkan hasil pembuatan vaksin tempatan Coryza berjangkit. Kerja simulasi ini dijalankan menggunakan alat simulasi Super Pro Designer v5.5. Sebanyak enam (6) skema khusus diujikaji menggunakan analisis pemprosesan dan kos kepada nisbah faedah (CBR) apabila pembuatan tahunan meningkat kepada 100%. Berdasarkan analisis ekonomi yang telah dilakukan, sesuatu skema khusus yang dipilih mempunyai keuntungan sebanyak USD 240 juta dengan margin kasar 9.13% dan pulangan atas pelaburan (ROI) sebanyak 46.12%. Selain itu juga, tempoh pembayaran balik bagi skema yang dipilih dianggarkan dalam tempoh tiga(3) tahun. KEYWORDS: process simulation; modelling; debottlenecking; optimisatio

Radiation therapy and photodynamic therapy for biliary tract and ampullary carcinomas

The purpose of radiation therapy for unresectable biliary tract cancer is to prolong survival or prolong stent patency, and to provide palliation of pain. For unresectable bile duct cancer, there are a number of studies showing that radiation therapy is superior to the best supportive care. Although radiation therapy is used in many institutions, no large randomized controlled trials (RCTs) have been performed to date and the evidence level supporting the superiority of this treatment is low. Because long-term relief of jaundice is difficult without using biliary stenting, a combination of radiation therapy and stent placement is commonly used. As radiation therapy, external-beam radiation therapy is usually performed, but combined use of intraluminal brachytherapy with external beam radiation therapy is more useful for making the treatment more effective. There are many reports demonstrating improved response rates as well as extended survival and time to recurrence achieved by this combination therapy. Despite the low level of the evidence, this combination therapy is performed at many institutions. It is expected that multiinstitutional RCTs will be carried out. Unresectable gallbladder cancer with a large focus is usually extensive, and normal organs with high radio sensitivity exist contiguously with it. Therefore, only limited anticancer effects are to be expected from external beam radiation therapy for this type of cancer. The number of reports on ampullary cancer is small and the role of radiation therapy in this cancer has not been established. Combination treatment for ampullary cancer consists of either a single use of intraoperative radiation therapy, postoperative external beam radiation therapy or intraluminal brachytherapy, or a combination of two or three of these therapies. Intraoperative radiation therapy is superior in that it enables precise irradiation to the target site, thereby protecting adjacent highly radiosensitive normal tissues from irradiation. There are reports showing extended survival, although not significant, in groups undergoing intraoperative or postoperative radiation therapy compared with groups without radiation therapy. To date, there are no reports of large RCTs focusing on the significance of radiation therapy as a postoperative adjuvant treatment, so its usefulness as a postoperative adjuvant treatment is not proven. An alternative treatment is photodynamic therapy. There is an RCT demonstrating that, in unresectable bile duct cancer, extended survival and improved quality of life (QOL) have been achieved through a combination of photodynamic therapy and biliary stenting, compared with biliary stenting alone. Results from large RCTs are desired

Combination of searches for Higgs boson pairs in pp collisions at \sqrts = 13 TeV with the ATLAS detector

This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy root s = 13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the b (b) over barb (b) over bar, b (b) over barW(+)W(-), b (b) over bar tau(+)tau(-), W+W-W+W-, b (b) over bar gamma gamma and W+W-gamma gamma final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (kappa(lambda)) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to -5.0 &lt; kappa(lambda) &lt; 12.0 (-5.8 &lt; kappa(lambda) &lt; 12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza-Klein Randall-Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model. For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2019.135103</p

Searches for lepton-flavour-violating decays of the Higgs boson in s=13\sqrt{s}=13 TeV pp\mathit{pp} collisions with the ATLAS detector

This Letter presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ , performed with the ATLAS detector at the LHC. The searches are based on a data sample of proton–proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb−1. No significant excess is observed above the expected background from Standard Model processes. The observed (median expected) 95% confidence-level upper limits on the leptonflavour-violating branching ratios are 0.47% (0.34+0.13−0.10%) and 0.28% (0.37+0.14−0.10%) for H → eτ and H → μτ , respectively.publishedVersio

Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb⁻¹ of pp collisions at \sqrts = 13 TeV with the ATLAS experiment

A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb−1 of proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t→γu of 2.8×10−5 (6.1×10−5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t→γc of 22×10−5 (18×10−5). © 2019 The Author(s