To the Editor: Existing data have suggested that rice intake was associated with elevated urinary excretion of total arsenic among pregnant women1 and in a population in Bangladesh whose major staple food is rice.2 Moreover, evidence suggests that brown rice may contain more arsenic than white rice.3 In this research, we aimed to examine brown and white rice consumption in relation to urinary excretion of arsenic among US adults. The study population consisted of 6,677 US adults (≥20 years) in the 2003–2010 National Health and Nutrition Examination Survey, who were randomly selected for urine arsenic analysis. Arsenic species were separated using high-performance liquid chromatography. Because inorganic arsenic, i.e., arsenous acid and arsenic acid, had low detection rates (<5%), we derived inorganic arsenic excretion by subtracting most abundant organic arsenic, i.e., arsenobetaine, from the total arsenic concentration.4 We calculated average white rice and brown rice intake assessed using two nonconsecutive 24-hour recalls. The first recall was done during an in- person interview, and the second recall was conducted through a telephone interview 3–10 days later.5 In statistical analysis, we log-transformed excretion of arsenic and used generalized linear models to compare the urinary arsenic concentration in white- and brown-rice eaters. We took into account the sampling weights specifically for participants included in the arsenic assessments. We used SAS 9.3 (SAS Institute Inc., Cary, NC) to perform statistical analysis. We observed that intakes of white and brown rice were both associated with higher total urinary arsenic concentrations, and the inorganic arsenic concentrations were not different between participants who primarily ate white rice versus those who ate brown rice: as shown in Figure the geometric mean ± SE of inorganic arsenic were 7.93 ± 0.24 μg/L for participants who did not eat rice (n = 5,443), 11.51 ± 0.49 μg/L for those who ate <1 cup/day white rice only (n = 562), and 13.06 ± 0.56 μg/L for those who ate ≥1 cup/day white rice only (n = 505; Ptrend < 0.001). For brown-rice eaters, the means were 10.92 ± 1.07 μg/L for those who ate <1 cup/day brown rice only (n = 73) and 13.05 ± 1.25 μg/L for those who ate ≥1 cup/day brown rice only (n = 67; Ptrend <0.001). There are only 27 participants who reported consuming both white rice and brown rice (mean total rice intake = 2.14 cup/day), and the geometric mean ± SE of their inorganic arsenic were 15.90 ± 2.38 μg/L. Urine excretion of total arsenic and inorganic arsenic by participants’ characteristics are presented in eTable 1 (https://links.lww.com/EDE/A961)FIGURE: Data are geometric means (in μg/L), adjusted for age (years), gender (male/female), race/ethnicity (white/black/Mexican American/others), body mass index (kg/m2), education (less than high school/high school/higher than high school), smoking status (never smoked/former smoker/current smoker), and urine creatinine level (mg/dl). Sample size in each category: never eat rice (n = 5,443); white rice only, <1 cup/day (n = 562); white rice only, ≥1 cup/day (n = 505); brown rice only, <1 cup/day (n = 73); brown rice only, ≥1 cup/day (n = 67); and eat both white and brown rice (n = 27).To the best of our knowledge, this study compared for the first time the two main types of rice, i.e., brown versus white rice, in terms of their contributions to inorganic arsenic exposures. Arsenic is primarily localized in outer layers of the grain.3 As a result, brown rice grains typically have higher arsenic levels than polished white rice.6 Jackson et al.7 recently reported a high inorganic arsenic concentrations in organic brown rice syrup. In this study, however, we did not observe a difference in urinary excretion of inorganic arsenic between participants who primarily ate brown rice and those who primarily ate white rice, although the number of brown-rice eaters was relatively small. One explanation for this finding is that the 2-day recalls may not be able to capture the long-term rice consumption. In addition, the outer layer part of rice grain, i.e., the pericarp and aleurone layer, which are removed during polishing process, makes up only a minor part of the grain (approximately 14%). Thus, at the same intake amount, the relative differences in arsenic concentrations between brown and white rice are less than those between bran per se and white rice.8 In summary, we found that consumption of white and brown rice showed similar associations with inorganic arsenic in urine. Data from prospective studies with larger sample size of rice eaters are needed to verify our findings. Hongyu Wu Department of Nutrition Harvard T.H. Chan School of Public Health Boston, MA Philippe Grandjean Department of Environmental Health Harvard T.H. Chan School of Public Health Boston, MA Institute of Public Health University of Southern Denmark Odense, Denmark Frank B. Hu Departments of Nutrition and Epidemiology Harvard T.H. Chan School of Public Health Boston, MA Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital and Harvard Medical School Boston, MA Qi Sun Department of Nutrition Harvard T.H. Chan School of Public Health Boston, MA Channing Division of Network Medicine Department of Medicine Brigham and Women’s Hospital and Harvard Medical School Boston, MA. [email protected]
No abstract is provided for this article.
Abstract Objectives: The results of earlier studies connecting dental diseases to cardiovascular diseases are inconsistent. Our aim in this cross‐sectional study was to investigate whether there are associations of dental diseases and diagnosed angina pectoris among the 1966 Northern Finland Birth Cohort. Materials and Methods: A postal questionnaire was sent to all cohort members in 1997–1998. The number of replies totalled 8690. Angina pectoris was determined by asking whether the respondent had been diagnosed with angina pectoris. Gingivitis, dental caries and tooth loss were determined on the basis of self‐reported gingival bleeding, presence of dental caries and six or more missing teeth. Results: We found overall associations of gingivitis (odds ratio (OR) 1.52, confidence interval (CI) 1.04–2.22), dental caries (OR 1.50, CI 1.04–2.18) and tooth loss (OR 1.53, CI 0.69–3.42) with the presence of angina pectoris. The associations were modified by gender and socioeconomic status. In addition, gingivitis, dental caries and tooth loss were also associated with several cardiovascular risk factors. Conclusion: There were associations of self‐reported gingivitis, dental caries and tooth loss with angina pectoris. However, the associations between dental diseases and cardiovascular risk factors suggest that the associations may be because of confounding.
Crack problems are formulated for solids characterized by a pure power hardening relation between the stresses and the strains. For such problems there are simple functional relationships between the amplitude of the dominant crack-tip singularity, as measured by the path-independent J-integral, and the applied load, the load point displacement, and the crack opening displacement. The solutions are valid for both incremental and deformation theories of plasticity; they also apply to problems involving steady-state creep. Numerical results are presented for the center-cracked strip of finite width under plane strain conditions. A preliminary discussion is given of the applicability of the solutions to large scale yielding fracture mechanics.
Residually compressed thin films are susceptible to spalling from substrates. A prerequisite for this to occur is that a separation develop at the interface large enough to allow buckling. Thereafter, the mechanisms of spalling are well-established. In this article, the mechanics of formation of the initial separation are addressed. Perturbations on the interface are deemed responsible for this process. Calculations of energy release rates for various interface morphologies have revealed that aperiodic perturbations can initiate and extend the separations to a length sufficient for buckling. Conversely, periodic perturbations trap separations at dimensions too small to buckle. Illustrations are given for an alumina film (scale) on Ni-based superalloys. Implications for life prediction models are explored.
Abstract Recent advances in surface engineering and soft lithography provide tools to fabricate patterned surfaces and microfluidic devices with dimensions comparable to the sizes of single mammalian cells. These technologies enable the studies of individual cells on spatially well‐defined, patterned surfaces, and in contact with patterned liquid media. They provide information about cells impossible to obtain from traditional biochemical techniques.
Because semiconductor nanowires can transport electrons and holes, they could function as building blocks for nanoscale electronics assembled without the need for complex and costly fabrication facilities. Boron- and phosphorous-doped silicon nanowires were used as building blocks to assemble three types of semiconductor nanodevices. Passive diode structures consisting of crossed p- and n-type nanowires exhibit rectifying transport similar to planar p-n junctions. Active bipolar transistors, consisting of heavily and lightly n-doped nanowires crossing a common p-type wire base, exhibit common base and emitter current gains as large as 0.94 and 16, respectively. In addition, p- and n-type nanowires have been used to assemble complementary inverter-like structures. The facile assembly of key electronic device elements from well-defined nanoscale building blocks may represent a step toward a "bottom-up" paradigm for electronics manufacturing.
