Study of the internal background of CsI(Tℓ) crystal detectors for dark matter search

A search for particle cold dark matter with CsI(Tℓ) crystal is being prepared at the Cheong-Pyeong underground laboratory in Korea. The background spectra of CsI(Tℓ) crystal detectors in a prototype shield were obtained. The lowest background count rate of the test sample of crystals is measured to be 64.7±5.1 counts/keV/kg/day in the energy range of 5–20 keV. Quantitative estimation of residual radioactive isotope in CsI(Tℓ) was made using the GEANT4 Monte Carlo simulation. Analysis results show that CsI(Tℓ) crystal could be a good candidate for direct detection of WIMPs when the contamination level of cesium radioisotopes is reduced to under a few mBq/kg.     

Hydrogen Permeation in Cold-Rolled High-Mn Twinning-Induced Plasticity Steels

Hydrogen permeation is investigated in cold-rolled Fe-0.6C-18Mn-(1.5Al) alloys. The hydrogen mobility is lower in cold-rolled alloys compared with annealed alloys. Al-containing alloy shows less deceleration of hydrogen mobility compared with the Al-free alloy. This is attributed to the reduced formation of mechanical twins and dislocations. Mechanical twins trap hydrogen strongly but are vulnerable to crack initiation; suppression of these is thought to be a major favorable influence of Al on hydrogen-induced mechanical degradation.     

Sleep-inducing effect of lettuce (Lactuca sativa) varieties on pentobarbital-induced sleep

Food Science and Biotechnology - The objective of this study was to investigate the sleep-inducing effect of lettuce varieties and the extracts derived from romaine lettuce on pentobarbital-induced...     

Ultimate strength of large scale reinforced concrete thin shell structures

This paper presents ultimate behavior of large scale reinforced concrete shell structures: hyperbolic cooling tower shell and hyperbolic paraboloid (HP) saddle shell. Both geometrical and material nonlinearities were considered in the analysis. To investigate the influence of concrete tension cracks on the structural behavior, the smeared crack model having the capability of representing double crack and crack rotation was used in the analysis. The biaxial stress state in shells is represented by the improved work-hardening plasticity concrete model, where the ductility increase phenomenon can be depicted. The load-displacement relationship, stress fields, occurrence and propagation of cracks in concrete and steel yield patterns are presented. Due to the factors such as modification in plasticity model, stiffness contribution in the doubly cracked elements, the model predicts a more ductile behavior than the results reported in the current literature. The failure of cooling tower shell seems to occur due to local yielding of meridional reinforcement in the windward meridian. In the case of HP saddle shell, structural instability occurs due to severe tension cracks in the shell part before yielding of reinforcement could occur.     

Optimization of a gravity‐driven membrane (GDM) system operated with simple manual cleanings for household drinking water treatment

Manual cleaning protocols were developed for a gravity‐driven membrane (GDM) module. Such a module is a promising solution for household water treatment in low‐ and middle‐income countries. A filtration system equipped with the GDM module was tested in a batchwise manner using three different feed water solutions. Two types of manual cleaning protocols were performed to delay the permeability decrease, namely cleaning between batches and long‐term cleaning (every 15 batches). The optimized protocol for cleaning between batches consisted of 3 twisting and 10 vertical shaking movements; the optimized long‐term cleaning protocol consisted of 70 vertical shaking movements for both the middle region of the module and the module header. These cleaning protocols allowed the filtration system to produce sufficient water to meet the minimum requirements for a five person family using all three kinds of feed water solutions. The module produced water without Escherichia coli, even for the wastewater influent.