Associations between indoor environment in residential buildings in wet and dry seasons and health of students in upper northern Thailand

We performed a repeated questionnaire study on home environment and health (six medical symptoms) in 1159 junior high school students (age 12.8 ± 0.7 years) in upper northern Thailand in wet and dry seasons. Data on outdoor temperature, relative humidity (RH), and air pollution were collected from nearest monitoring station. Odds ratios (OR) were calculated by multi-level logistic regression. Most common symptoms were rhinitis (62.5%), headache (49.8%), throat (42.8%), and ocular symptoms (42.5%). Ocular symptoms were more common at lower RH and rhinitis more common in dry season. Water leakage (28.2%), indoor mold (7.1%), mold odor (4.1%), and windowpane condensation (13.6%) were associated with all six symptoms (ORs: 1.3–3.5). Other risk factors included cat keeping, environmental tobacco smoke (ETS), other odor than mold odor, gas cooking, and cooking with biomass fire. Biomass burning inside and outside the home for other reasons than cooking was associated with all six symptoms (ORs: 1.5–2.6). Associations between home environment exposure and rhinitis were stronger in wet season. In conclusion, dampness-related exposure, windowpane condensation, cat keeping, ETS, gas cooking, and biomass burning can impair adolescent health in upper northern Thailand. In subtropical areas, environmental health effects should be investigated in wet and dry seasons.     

Probing the reaction pathway of dehydrogenation of the LiNH2 + LiH mixture using in situ H NMR spectroscopy

Using variable temperature in situ ¹H NMR spectroscopy on a mixture of LiNH₂ + LiH that was mechanically activated using high-energy ball milling, the dehydrogenation of the LiNH₂ + LiH to Li₂NH + H₂ was investigated. The analysis indicates NH₃ release at a temperature as low as 30 °C and rapid reaction between NH₃ and LiH at 150 °C. The transition from NH₃ release to H₂ appearance accompanied by disappearance of NH₃ confirms unambiguously the two-step elementary reaction pathway proposed by other workers.     

Light charged-particle production in 96 MeV neutron-induced reactions on carbon and oxygen

In recent years, an increasing number of applications involving fast neutrons have been developed or are under consideration, e.g. radiation treatment of cancer, neutron dosimetry at commercial aircraft altitudes, soft-error effects in computer memories, accelerator-driven transmutation of nuclear waste and energy production and determination of the response of neutron detectors. Data on light-ion production in light nuclei such as carbon, nitrogen and oxygen are particularly important in calculations of dose distributions in human tissue for radiation therapy at neutron beams, and for dosimetry of high-energy neutrons produced by high-energy cosmic radiation interacting with nuclei (nitrogen and oxygen) in the atmosphere. When studying neutron dose effects, it is especially important to consider carbon and oxygen, since they are, by weight, the most abundant elements in human tissue. Preliminary experimental double-differential cross sections of inclusive light-ion (p, d, t, (3)He and alpha) production in carbon induced by 96-MeV neutrons have been presented. Energy spectra were measured at eight laboratory angles: 20, 40, 60, 80, 100, 120, 140 and 160 degrees . Measurements were performed at The Svedberg Laboratory (TSL), Uppsala, using the dedicated MEDLEY experimental setup. The authors have earlier reported experimental double-differential cross sections of inclusive light-ion production in oxygen. In this paper, the deduced kerma coefficients for oxygen has been presented and compared with reaction model calculations.     

Comparisons between MgH2- and LiH-containing systems for hydrogen storage applications

The present study compares the dehydrogenation kinetics of (2_LiNH2+_MgH2)$(2{\mathrm{LiNH}}_2+{\mathrm{MgH}}_2)$ and (_LiNH2+LiH)$({\mathrm{LiNH}}_2+\mathrm{LiH})$ systems and their vulnerabilities to the NH₃ emission problem. The (2_LiNH2+_MgH2)$(2{\mathrm{LiNH}}_2+{\mathrm{MgH}}_2)$ and (_LiNH2+LiH)$({\mathrm{LiNH}}_2+\mathrm{LiH})$ mixtures with different degrees of mechanical activation are investigated in order to evaluate the effect of mechanical activation on the dehydrogenation kinetics and NH₃ emission rate. The activation energy for dehydrogenation, the phase changes at different stages of dehydrogenation, and the level of NH₃ emission during the dehydrogenation process are studied. It is found that the (2_LiNH2+_MgH2)$(2{\mathrm{LiNH}}_2+{\mathrm{MgH}}_2)$ mixture has a higher rate for hydrogen release, slower rate for approaching a certain percentage of its equilibrium pressure, higher activation energy, and more NH₃ emission than the (_LiNH2+LiH)$({\mathrm{LiNH}}_2+\mathrm{LiH})$ mixture. On the basis of the phenomena observed, the reaction mechanism for the dehydrogenation of the (2_LiNH2+_MgH2)$(2{\mathrm{LiNH}}_2+{\mathrm{MgH}}_2)$ system has been proposed for the first time. Approaches for further improving the hydrogen storage behavior of the (2_LiNH2+_MgH2)$(2{\mathrm{LiNH}}_2+{\mathrm{MgH}}_2)$ system are discussed in light of the newly proposed reaction mechanism.     

Relation of DDT residues to plasma retinol, alpha-tocopherol, and beta-carotene during pregnancy and malaria infection: a case-control study in Karen women in northern Thailand

Populations living in endemic malaria areas maybe exposed simultaneously to DDT and malaria infection. DDT may impair status of vitamins, which are implicated in the immunity and pathophysiology of malaria. To explore possible interactions, DDT residues, retinol, alpha-tocopherol, beta-carotene and cholesterol were measured in plasma samples of malaria-infected pregnant women (cases, n=50) and age matched malaria-free controls (n=58). DDT residues were found in all samples: mean (sd) total DDT levels of 29.7 and 32.7 ng/ml in cases and controls, respectively. Mean (sd) p,p'-DDT was higher in the controls than the cases (13.5 vs. 9.5 ng/ml, p=0.006). Malaria infection was associated with lower mean (sd) plasma retinol (0.69 vs. 1.23 micromol/L) and cholesterol (2.62 vs. 3.48 mmol/L) compared to controls (p<0.001). Mean (sd) plasma alpha-tocopherol (7.65 vs. 15.58 micromol/L) and alpha-tocopherol/cholesterol ratio (2.3 vs. 6.7 micromol/L/mmol/L) were significantly lower among the controls (p<0.001). Mean (sd) plasma beta-carotene was low (<0.3 micromol/L) in both groups, but higher among malaria cases (0.19 vs. 0.15 micromol/L). Plasma retinol among the controls showed highly significant positive correlations with individual DDT compounds, particularly with p,p'-DDT (r=0.51, p<0.001). Plasma alpha-tocopherol and beta-carotene seemed not to be affected by DDT residues.     

The TSL neutron beam facility

A new quasi-monoenergetic neutron beam facility has been constructed at The Svedberg Laboratory (TSL) in Uppsala, Sweden. Key features include a neutron energy range of 11-175 MeV, high fluxes, user flux control, flexible neutron field size and shape, and spacious and easily accessible user area. The first results of the beam characterisation measurements are reported.     

Study the effects of mechanical activation on Li–N–H systems with H and Li solid-state NMR

To gain insight into the effects of mechanical activation (MA) on the hydrogen desorption of the lithium amide (LiNH₂) and lithium hydride (LiH) mixture, LiNH₂ and LiH + LiNH₂ were mechanically activated by high-energy ball milling. The formed products were studied with in situ ¹H and ⁶Li nuclear magic angle spinning (MAS) magnetic resonance (NMR) spectroscopy from ambient temperature to 180 °C. Up-field chemical shift was observed in ⁶Li MAS NMR spectra with increased milling time, indicating that average local electronic structure around Li nuclei was modified during MA. ¹H MAS NMR was used to dynamically probe ammonia release from the activated LiNH₂ at temperature as low as 50 °C. In the case of activated LiH + LiNH₂ mixtures, the ¹H MAS NMR results implied that MA enhanced the dehydrogenation reaction of LiNH₂ + LiH = Li₂NH + H₂.