Search for nucleon decay into charged antilepton plus meson in 0.316 megaton . years exposure of the Super-Kamiokande water Cherenkov detector

We have searched for proton decays into a charged antilepton (e+, μ+) plus a meson (η, ρ0, ω) and for neutron decays into a charged antilepton (e+, μ+) plus a meson (π−, ρ−) using Super-Kamiokande I-IV data, corresponding to 0.316  megaton⋅years of exposure. This measurement updates the previous published result by using 2.26 times more data and improved analysis methods. No significant evidence for nucleon decay is observed and lower limits on the partial lifetime of the nucleon are obtained. The limits range from 3×1031 to 1×1034  years at 90% confidence level, depending on the decay mode

Search for Neutrinos in Super-Kamiokande Associated with the GW170817 Neutron-star Merger

We report the results of a neutrino search in Super-Kamiokande (SK) for coincident signals with the first detected gravitational wave (GW) produced by a binary neutron-star merger, GW170817, which was followed by a short gamma-ray burst, GRB170817A, and a kilonova/macronova. We searched for coincident neutrino events in the range from 3.5 MeV to ~100 PeV, in a time window ±500 s around the gravitational wave detection time, as well as during a 14-day period after the detection. No significant neutrino signal was observed for either time window. We calculated 90% confidence level upper limits on the neutrino fluence for GW170817. From the upward-going-muon events in the energy region above 1.6 GeV, the neutrino fluence limit is ${16.0}_{-0.6}^{+0.7}$ (${21.3}_{-0.8}^{+1.1}$) cm−2 for muon neutrinos (muon antineutrinos), with an error range of ±5° around the zenith angle of NGC4993, and the energy spectrum is under the assumption of an index of −2. The fluence limit for neutrino energies less than 100 MeV, for which the emission mechanism would be different than for higher-energy neutrinos, is also calculated. It is 6.6 × 107 cm−2 for anti-electron neutrinos under the assumption of a Fermi–Dirac spectrum with average energy of 20 MeV

Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector

Scintillator ageing of the T2K near detectors from 2010 to 2021

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9–2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3–5.4% per year, while the short component of the attenuation length did not show any conclusive degradation

Rapid DNA hybridization in microfluidics

10.1016/j.trac.2011.09.014Individualized genetic diagnostics are emerging as critical medical tools in the provision of personalized care, rapid disease screening and follow-up therapy, and in defense, security and environmental applications. The advances made in DNA-detection techniques and micro-total analysis systems have fostered the development of new micro-devices that promise to provide fast genetic testing at the point of need within minutes, if rapid DNA-DNA hybridization can be achieved. In recent years, several strategies have been developed to enhance DNA-hybridization kinetics and the overall sensitivity and reliability of sequence-specific DNA analysis. This article reviews new concepts and approaches employed to achieve rapid hybridization and detection, and the promise to take genetic testing out of specialized laboratories into the field

Low-medium resolution HLA-DQ2/DQ8 typing for coeliac disease predisposition analysis by colorimetric assay

10.1007/s00216-012-5898-6Abstract Coeliac disease is an inflammation of the small intestine, occurring in genetically susceptible individuals triggered by the ingestion of gluten. Human Leukocyte Antigens (HLA) DQ2 and DQ8 gene have been identified as key genetic factors in coeliac disease as they are presented in almost 100 % of the patients. These genes are encoded by the combination of certain alleles in the DQA and DQB region of chromosome 6. Specifically, DQA1*05:01 and DQB1*02:01 alleles for serologically defined leukocyte antigen DQ2 cis, DQA1*05:05 and DQB1*02:02 for DQ2 trans and DQA1*03:01 and DQB1*03:02 alleles for the DQ8. Specific identification of these alleles is a challenge due to the high number of alleles that have been identified so far: 46 in the DQA region and 160 in the DQB region (as of IMGT/HLA Database 10/2011 release). In the reported work, the development of a multiplex colorimetric assay for the low to medium HLA typing of the DQ2 and DQ8 genes is presented. The optimisation of probe design and assay conditions, performed by both surface plasmon resonance and enzyme-linked oligonucleotide assay, are reported. Finally, the performances of the developed typing platform were validated by the analysis of real patient samples and HLA typing, compared with those obtained using hospital based typing technology and an excellent correlation obtained

Facile electrochemical hydrogenation and chlorination of glassy carbon to produce highly reactive and uniform surfaces for stable anchoring of thiolated molecules

10.1002/chem.201402051Carbon is a highly adaptable family of materials and is one of the most chemically stable materials known, providing a remarkable platform for the development of tunable molecular interfaces. Herein, we report a two-step process for the electrochemical hydrogenation of glassy carbon followed by either chemical or electrochemical chlorination to provide a highly reactive surface for further functionalization. The carbon surface at each stage of the process is characterized by AFM, SEM, Raman, attenuated total reflectance (ATR) FTIR, X-ray photoelectron spectroscopy (XPS), and electroanalytical techniques. Electrochemical chlorination of hydrogen-terminated surfaces is achieved in just 5 min at room temperature with hydrochloric acid, and chemical chlorination is performed with phosphorus pentachloride at 50?°C over a three-hour period. A more controlled and uniform surface is obtained using the electrochemical approach, as chemical chlorination is observed to damage the glassy carbon surface. A ferrocene-labeled alkylthiol is used as a model system to demonstrate the genericity and potential application of the highly reactive chlorinated surface formed, and the methodology is optimized. This process is then applied to thiolated DNA, and the functionality of the immobilized DNA probe is demonstrated. XPS reveals the covalent bond formed to be a C[BOND]S bond. The thermal stability of the thiolated molecules anchored on the glassy carbon is evaluated, and is found to be far superior to that on gold surfaces. This is the first report on the electrochemical hydrogenation and electrochemical chlorination of a glassy carbon surface, and this facile process can be applied to the highly stable functionalization of carbon surfaces with a plethora of diverse molecules, finding wi