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Cadmium (Cd) is the most potent nephrotoxic heavy metal and may affect bone; it also has a long biological half-life in the human body. This study was designed to assess the effect of environmental low-level Cd exposure on kidney function and bone in the general population. The subjects of this cross-sectional study were 1907 healthy Korean adults who had not been exposed to Cd occupationally. We analyzed the concentrations of Cd in the urine, markers of renal tubule damage, such as β-microglobulin (β-MG) and N-acetyl-β-D-glucosaminidase (NAG) activity in the urine, calculated the estimated glomerular filtration rate (eGFR) using serum creatinine, and measured bone mineral density (BMD). Also, we analyzed malondialdehyde (MDA) levels in the urine. The geometric mean concentration of Cd in urine was higher in women (1.36 μg/g creatinine) than in men (0.82 μg/g creatinine). Urinary Cd was significantly positively correlated with urinary β-MG and NAG activity, whereas it was negatively correlated with eGFR and BMD. The risk of renal tubule damage was significantly associated with urine Cd level, and the association remained significant after controlling for various confounding variables. However, no association was observed between urinary Cd level and glomerular dysfunction or bone damage. The concentration of MDA was increased with urinary Cd level in a dose-dependent manner. These findings suggest that low-level environmental Cd exposure may cause microscopic damage to renal tubules through oxidative stress but might not impair kidney glomeruli or bones. [ABSTRACT FROM AUTHOR]

This study examined whether palm cooling (PC) could reduce heat strain, measured through changes in core, mean skin, mean body temperatures, and thermal sensation in resting hyperthermic subjects wearing chemical protective garments. Ten male subjects performed three exercise bouts (6.1 km h(-1), 2-4% grade) in a hot, dry environment [mean (SD) air temperature 42.2 (0.5 degrees C), relative humidity 36.5 (1%)] until core temperature reached 38.8 degrees C. Subjects then simulated transport in an armoured vehicle by resting in a seated position for 50 min with either no cooling (NC), (PC at 10 degrees C) or palm cooling with vacuum application around the hand (PCVAC, 10 degrees C, 7.47 kPa negative pressure). Core, skin, and mean body temperatures with PC and PCVAC were lower (P < 0.05) than NC from 15 to 50 min of cooling, and thermal sensation was lower (P < 0.05) from 30 to 50 min, with no differences in any variables between PC and PCVAC. Maximal heat extraction averaged 42 (12 W), and core temperature was reduced by 0.38 (0.21 degrees C) after 50 min of PC. Heat extraction with PC was modest compared to other cooling approaches in the literature. [ABSTRACT FROM AUTHOR]

In this study, we obtain experimental understanding of the mode characteristics of a droplet placed on a flat surface under periodic forced vibrations. The detachment conditions for the droplet on the surface were also studied. In order to estimate the resonance frequency of a droplet placed on a hydrophobic surface, theoretical modelling was combined with experimental approaches. Two high speed cameras were used to observe droplet characteristics, including mode shape, detachment, occurrence of secondary droplet breakup, and horizontal torsional motion. Two cameras were installed to the right above the droplet and at the side of the droplet. There was no more than an 18% discrepancy between the theoretical and experimental resonance frequencies. This discrepancy was likely caused by several factors such as contact line friction, nonlinear wall adhesion, and experimental uncertainty. When applying a relatively low voltage to a speaker, the contact line of a droplet was pinned and shape oscillations of the droplet appeared in a bilaterally symmetric way. In contrast, at higher voltages, the contact line depinned and the shape oscillations became more active. For excitation frequencies identical to the mode frequency, the lobe size of the droplet was relatively larger than that at neighbouring frequencies. The experimental results also indicate that the generation and complete detachment of small-scale droplets occur only at the 2nd mode. Graphical abstract: [ABSTRACT FROM AUTHOR]

The accuracy of forensic age estimation based on the chronology of second (M2) and third molar (M3) development was investigated using 2,087 orthopantomograms of Korean men and women aged between 3 and 23 years. The developmental stages of M2s and M3s in these subjects were classified using the criteria of Demirjian. Inter-observer reliability and statistical data on each stage of mineralization of M2s and M3s were evaluated. The left-right symmetries of the maturation degrees in the M2s and M3s were observed in both sexes, between which no arch differences were found, but statistically significant sex-specific differences were observed in some stages of M2 and M3 development. In multiple regression analysis, a strong positive relationship was observed between age and mineralization of M2s and M3s. The regression formulas for estimating the age of Koreans were presented based on sex and combination of teeth. These results suggest that the developments of second and third molars can be considered as valuable age indicators in Korean adolescents and young adults. [ABSTRACT FROM AUTHOR]

Korean montmorillonite was intercalated with Al-hydroxypolycation solution aged for 1, 4 and 7 days and then calcined at 400 ‡C, 600 ‡C and 760 ‡C, respectively. Basal spacings by XRD, pore structure (micro- and mesopore distributions and surface areas) by nitrogen (or argon) adsorption at liquid nitrogen (or argon) temperature and acidity (distribution and acid-amount) by NH3-TPD were investigated for the samples. The basal spacing formed by intercalation appeared at about 17 å and decreased with the heating temperature for the sample intercalated with the Alhydroxypolycation solution aged for 1 day. However, for the one aged for 7 days, the spacing remained constant. The total surface area and pore-volume also increased with aging time of the Al-solution, in which micro-pore area increased more rapidly. Argon adsorption indicated that three modal distributions of 3.3, 3.7 and 4.3 å in micropore radius appeared, in which 3.3 å readily was reduced by heating. NH3-TPD showed that two ammonia-desorption peaks appeared at 230 ‡C and 430 ‡C, respectively. The maximum acid-amount for the intercalated sample appeared as 86 meq./100 g-solid, and the values decreased with the heating temperature, especially for the peak at 430 ‡C. [ABSTRACT FROM AUTHOR]