We make use of the EDELWEISS-III array of germanium bolometers to search for electron interactions at the keV scale induced by phenomena beyond the Standard Model. A 90% C.L. lower limit is set on ...the electron lifetime decaying to invisibles, ?>1.2×1024 years. We investigate the emission of axions or axionlike particles (ALPs) by the Sun, constraining the coupling parameters gae<1.1×10?11 and gae×gaNeff<3.5×10?17 at 90% C.L. in the massless limit. We also directly search for the absorption of bosonic dark matter particles that would constitute our local galactic halo. Limits are placed on the couplings of ALPs or hidden photon dark matter in the mass range 0.8–500 keV/c2. Prospects for searching for dark matter particles with masses down to 150 eV/c2 using improved detectors are presented.
Crystalline silicon (Si) nanoparticles present an extremely promising object for bioimaging based on photoluminescence (PL) in the visible and near-infrared spectral regions, but their efficient PL ...emission in aqueous suspension is typically observed after wet chemistry procedures leading to residual toxicity issues. Here, we introduce ultrapure laser-synthesized Si-based quantum dots (QDs), which are water-dispersible and exhibit bright exciton PL in the window of relative tissue transparency near 800 nm. Based on the laser ablation of crystalline Si targets in gaseous helium, followed by ultrasound-assisted dispersion of the deposited films in physiological saline, the proposed method avoids any toxic by-products during the synthesis. We demonstrate efficient contrast of the Si QDs in living cells by following the exciton PL. We also show that the prepared QDs do not provoke any cytoxicity effects while penetrating into the cells and efficiently accumulating near the cell membrane and in the cytoplasm. Combined with the possibility of enabling parallel therapeutic channels, ultrapure laser-synthesized Si nanostructures present unique object for cancer theranostic applications.
Initial performance of the COSINE-100 experiment Adhikari, G.; Adhikari, P.; de Souza, E. Barbosa ...
The European physical journal. C, Particles and fields,
02/2018, Letnik:
78, Številka:
2
Journal Article
Recenzirano
Odprti dostop
COSINE is a dark matter search experiment based on an array of low background NaI(Tl) crystals located at the Yangyang underground laboratory. The assembly of COSINE-100 was completed in the summer ...of 2016 and the detector is currently collecting physics quality data aimed at reproducing the DAMA/LIBRA experiment that reported an annual modulation signal. Stable operation has been achieved and will continue for at least 2 years. Here, we describe the design of COSINE-100, including the shielding arrangement, the configuration of the NaI(Tl) crystal detection elements, the veto systems, and the associated operational systems, and we show the current performance of the experiment.
We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with ...muon-induced backgrounds. Muon generation and transport are performed using the MUSIC/MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φ(n)(ν)=1.0 × 10(-9) cm(-2) s(-1). We predict 3.49 × 10(-5) counts/day/kg/keV, which accounts for less than 0.3% of the DAMA signal modulation amplitude.
We present new constraints on the dark matter-induced annual modulation signal using 1.7 years of COSINE-100 data with a total exposure of 97.7 kg yr. The COSINE-100 experiment, consisting of 106 kg ...of NaI(Tl) target material, is designed to carry out a model-independent test of DAMA/LIBRA's claim of WIMP discovery by searching for the same annual modulation signal using the same NaI(Tl) target. The crystal data show a 2.7 cpd/kg/keV background rate on average in the 2-6 keV energy region of interest. Using a χ-squared minimization method we observe best fit values for modulation amplitude and phase of 0.0092±0.0067 cpd/kg/keV and 127.2±45.9 d, respectively.
We studied a role of the inducible heat shock protein 70 (Hsp70) in cellular response to radiosensitizing treatments with inhibitors of the heat shock protein 90 (Hsp90) chaperone activity. Cell ...lines derived from solid tumors of different origin were treated with the Hsp90 inhibitors (17AAG, geldanamycin, radicicol, NVP-AUY922) or/and γ-photon radiation. For comparison, human cells of the non-cancerous origin were subjected to the same treatments. We found that the Hsp90 inhibitors yielded considerable radiosensitization only when they cause early and pronounced Hsp70 induction; moreover, a magnitude of radiosensitization was positively correlated with the level of Hsp70 induction. The quantification of Hsp70 levels in Hsp90 inhibitor-treated normal and cancer cells enabled to predict which of them will be susceptible to any Hsp90-inhibiting radiosensitizer as well as what concentrations of the inhibitors ensure the preferential cytotoxicity in the irradiated tumors without aggravating radiation damage to adjacent normal tissues. Importantly, the Hsp70 induction in the Hsp90 inhibitor-treated cancer cells appears to be their protective response that alleviates the tumor-sensitizing effects of the Hsp90 inactivation. Combination of the Hsp70-inducing inhibitors of Hsp90 with known inhibitors of the Hsp induction such as quercetin, triptolide, KNK437, NZ28 prevented up-regulation of Hsp70 in the cancer cells thereby increasing their post-radiation apoptotic/necrotic death and decreasing their post-radiation viability/clonogenicity. Similarly, co-treatment with the two inhibitors conferred the enhanced radiosensitization of proliferating rather than quiescent human vascular endothelial cells which may be used for suppressing the tumor-stimulated angiogenesis. Thus, the easily immunodetectable Hsp70 induction can be a useful marker for predicting effects of Hsp90-inhibiting radiosensitizers on tumors and normal tissues exposed to ionizing radiation. Moreover, targeting the Hsp70 induction in Hsp90 inhibitor-treated cancer cells and tumor vasculature cells may beneficially enhance the radiosensitizing effect.
We report the results of experimental studies and numerical simulation of the dynamics of the electron-hole pairs formation in silicon under the action of a two-period terahertz pulse with a maximum ...electric field strength of up to 23 MV/cm. It is shown that an inhomogeneous distribution of the charge carrier concentration over the depth of the silicon sample is formed, which persists for several microseconds. This inhomogeneity is formed due to a sharp increase in the rate of filling the conduction band with free carriers in the subsurface input layer of the silicon wafer, which occurs at a field strength above 15 MV/cm.
The aim of this study was to determine how sacubitril/valsartan compared with valsartan in an outpatient setting affects left ventricular remodeling in heart failure with reduced ejection fraction ...and functional (or secondary) mitral regurgitation (SMR) due to the effect of dual inhibition of the renin-angiotensin system and neprilysin. The outpatient study included 90 patients with chronic SMR who were followed up for 12 months. They received sacubitril/valsartan or valsartan instead of the more commonly used angiotensin-converting enzyme inhibitor enalapril for heart failure, in addition to standard medical therapy for heart failure. The difference in NT-proBNP change between groups was the primary endpoint. Changes in effective regurgitation orifice area, left ventricular ejection fraction, left ventricular end-systolic and end-diastolic volume indices, left atrial volume index, E/e' index, and exercise tolerance on the 6-minute walk test were secondary endpoints. In the treatment efficacy analysis, NT-proBNP levels decreased significantly by 37% in the sacubitril/valsartan group and by 11% in the valsartan group (P<0.001). Ejection fraction and exercise tolerance (increase in walking distance in the 6-min test) increased in the sacubitril/valsartan group (P<0.05). Also, in this group, the effective area of the regurgitation orifice, the left atrial volume index, the E/e' index, and the indices of the end-systolic and end-diastolic volume of the left ventricle (P<0.05) decreased more pronouncedly. Compared with valsartan, treatment with sacubitril/valsartan led to a significant improvement in cardiac remodeling in patients with SMR and heart failure with reduced ejection fraction.