bluuebunny/crossref_metadata_2025 huggingface dataset:
Presence of necrotic strains of Potato virus Y in Mexican potatoes
Authors: Ramírez-Rodríguez Victoriano Roberto , Aviña-Padilla Katia , Frías-Treviño Gustavo , Silva-Rosales Laura , Martínez-Soriano Juan Pablo
Published: May 2009

As part of a routine screening for the possible presence of the necrotic strains of potato virus Y affecting potatoes in Mexico, five PVY isolates were submitted to biological and molecular analysis. Considering their serological properties, two belong to the common strain (O) and three to the necrotic strain (N). All the isolates induced vein necrosis in Nicotiana tabacum. To characterize the isolates, 5' NTR and P1 genes were sequenced and compared with sequences from GenBank database. Nucleotide sequence similarity ranged from 47–100% in the 5' NTR and from 63–100% in the P1 coding region. The lowest amino acid similarity between sequences of P1 gene was 55%. In phylogenetic trees of 5'NTR analysis, two PVYO Mexican isolates clustered with other PVYO isolates. In turn, the three PVYN isolates grouped with PVYN-NTN isolates. The phylogenetic analysis of P1 sequences (nucleotide and amino acid) showed two PVYO isolates grouping next to N-NTN cluster. A detailed analysis of the PVYO isolates showed two potential recombination regions in the P1 gene, in contrast to 5'NTR where no recombination was detected.
ATF6α induces XBP1-independent expansion of the endoplasmic reticulum
Authors: Bommiasamy Hemamalini , Back Sung Hoon , Fagone Paolo , Lee Kyungho , Meshinchi Sasha , Vink Elizabeth , Sriburi Rungtawan , Frank Matthew , Jackowski Suzanne , Kaufman Randal J. , Brewer Joseph W.
Published: May 2009

A link exists between endoplasmic reticulum (ER) biogenesis and the unfolded protein response (UPR), a complex set of signaling mechanisms triggered by increased demands on the protein folding capacity of the ER. The UPR transcriptional activator X-box binding protein 1 (XBP1) regulates the expression of proteins that function throughout the secretory pathway and is necessary for development of an expansive ER network. We previously demonstrated that overexpression of XBP1(S), the active form of XBP1 generated by UPR-mediated splicing of Xbp1 mRNA, augments the activity of the cytidine diphosphocholine (CDP-choline) pathway for biosynthesis of phosphatidylcholine (PtdCho) and induces ER biogenesis. Another UPR transcriptional activator, activating transcription factor 6α (ATF6α), primarily regulates expression of ER resident proteins involved in the maturation and degradation of ER client proteins. Here, we demonstrate that enforced expression of a constitutively active form of ATF6α drives ER expansion and can do so in the absence of XBP1(S). Overexpression of active ATF6α induces PtdCho biosynthesis and modulates the CDP-choline pathway differently than does enforced expression of XBP1(S). These data indicate that ATF6α and XBP1(S) have the ability to regulate lipid biosynthesis and ER expansion by mechanisms that are at least partially distinct. These studies reveal further complexity in the potential relationships between UPR pathways, lipid production and ER biogenesis.
Origins and activities of the eukaryotic exosome
Authors: Lykke-Andersen Søren , Brodersen Ditlev E. , Jensen Torben Heick
Published: May 2009

The exosome is a multi-subunit 3′-5′ exonucleolytic complex that is conserved in structure and function in all eukaryotes studied to date. The complex is present in both the nucleus and cytoplasm, where it continuously works to ensure adequate quantities and quality of RNAs by facilitating normal RNA processing and turnover, as well as by participating in more complex RNA quality-control mechanisms. Recent progress in the field has convincingly shown that the nucleolytic activity of the exosome is maintained by only two exonuclease co-factors, one of which is also an endonuclease. The additional association of the exosome with RNA-helicase and poly(A) polymerase activities results in a flexible molecular machine that is capable of dealing with the multitude of cellular RNA substrates that are found in eukaryotic cells. Interestingly, the same basic set of enzymatic activities is found in prokaryotic cells, which might therefore illustrate the evolutionary origin of the eukaryotic system. In this Commentary, we compare the structural and functional characteristics of the eukaryotic and prokaryotic RNA-degradation systems, with an emphasis on some of the functional networks in which the RNA exosome participates in eukaryotes.
Association of the Aromatase Gene Alleles With BMD:Epidemiological and Functional Evidence
Authors: Riancho José A , Sañudo Carolina , Valero Carmen , Pipaón Carlos , Olmos José M , Mijares Verónica , Fernández-Luna José L , Zarrabeitia María T
Published: May 2009

BMD has a strong heritable component. Estrogen activity depends on the aromatization of androgenic precursors in nongonadal tissues both in postmenopausal women and men. Therefore, aromatase is an appealing candidate gene to explain, in part, the genetic component of BMD. In fact, an association between aromatase polymorphisms and BMD has been previously reported in some relatively small groups. In this study, we explored the relationship between several SNPs in the aromatase region and hip BMD in 1163 postmenopausal women. We found significant differences across genotypes, particularly in older women. The BMD differences between homozygous women with opposing genotypes were 4.2% in the whole group and 7.3% in women >67 yr of age. Body weight was significantly associated with BMD also, but there was no evidence for a statistically significant interaction between body weight and aromatase polymorphisms. Electrophoretic mobility shift assays suggested the binding of the CEBPβ transcription factor to the C/G rs1062033 locus, located ∼12 kb upstream of the translation start site. Experiments of transient transfection of osteoblastic cells with luciferase reporters showed differences in the transcriptional activity of alleles C and G at this locus, with different responses to the co-transfection of a CEBPβ expression vector. Furthermore, evidence for differential allelic expression was found in bone tissue samples. In conclusion, polymorphisms in a 12-kb region of the aromatase gene are associated with BMD in postmenopausal women, particularly during the late postmenopausal period. In vitro functional studies point to rs1062033 as a true regulatory polymorphism.
Bone and Muscle Development During Puberty in Girls: A Seven-Year Longitudinal Study
Authors: Xu Leiting , Nicholson Patrick , Wang Qingju , Alén Markku , Cheng Sulin
Published: May 2009

The growth of lean mass precedes that of bone mass, suggesting that muscle plays an important role in the growth of bone. However, to date, no study has directly followed the growth of bone and muscle size through puberty and into adulthood. This study aimed to test the hypothesis that the growth of muscle size precedes that of bone size (width and length) and mass during puberty. Bone and muscle properties were measured using pQCT and DXA in 258 healthy girls at baseline (mean age, 11.2 yr) and 1-, 2-, 3–4- and 7-yr follow-up. Growth trends as a function of time relative to menarche were determined from prepuberty to early adulthood for tibial length (TL), total cross-sectional area (tCSA), cortical CSA (cCSA), total BMC (tBMC), cortical volumetric BMD (cBMD), and muscle CSA (mCSA) in hierarchical models. The timings of the peak growth velocities for these variables were calculated. Seventy premenopausal adults, comprising a subset of the girl's mothers (mean age, 41.5 yr), were included for comparative purposes. In contrast to our hypothesis, the growth velocity of mCSA peaked 1 yr later than that of tibial outer dimensions (TL and tCSA) and slightly earlier than tBMC. Whereas TL ceased to increase 2 yr after menarche, tCSA, cCSA, tBMC, and mCSA continued to increase and were still significantly lower than adult values at the age of 18 yr (all p < 0.01). The results do not support the view that muscle force drives the growth of bone size during puberty.
Bone Health in Children and Adolescents After Renal Transplantation
Authors: Valta Helena , Mäkitie Outi , Rönnholm Kai , Jalanko Hannu
Published: May 2009

The basis for lifelong bone health is established in childhood and adolescence. Whereas pediatric renal transplant (RTx) patients are at risk for impaired bone mass gain and fractures, scarce data on this subject are available. We performed a cross-sectional and longitudinal study of bone health in a national cohort of 106 pediatric RTx patients (median age, 12.6 yr; median follow-up, 5.1 yr after RTx). The patients underwent clinical evaluation, DXA for BMD, and spinal imaging for vertebral fractures. In longitudinal analysis, the median lumbar spine BMD Z-score was lowest (median, −1.0) at 1 yr postoperatively but increased to a peak value of −0.2 at 5 yr. In boys, the lumbar spine BMD Z-score increased also during puberty but decreased in girls. In cross-sectional analysis, the lumbar spine, hip, and whole body BMD Z-scores were < −2 SD in 4%, 6%, and 6% of the patients, respectively. Sixteen percent had sustained peripheral fractures, and 8% had vertebral fractures. Female sex and age >15 yr (OR, 56.26; 95% CI, 5.17–611.82; p = 0.0007) as well as high plasma PTH levels (OR, 4.03; 95% CI, 1.37–11.85; p = 0.009) were significant predictors for low BMD. Three-year cumulative glucocorticoid dose, outside the immediate post-RTx years, was not associated with BMD parameters. The observed BMD results were satisfactory. However, the high (8%) prevalence of vertebral fractures warrants careful evaluation of bone health in these patients.
Sclerostin Mediates Bone Response to Mechanical Unloading Through Antagonizing Wnt/β-Catenin Signaling
Authors: Lin Chuwen , Jiang Xuan , Dai Zhongquan , Guo Xizhi , Weng Tujun , Wang Jun , Li Yinghui , Feng Guoyin , Gao Xiang , He Lin
Published: May 2009

Reduced mechanical stress leads to bone loss, as evidenced by disuse osteoporosis in bedridden patients and astronauts. Osteocytes have been identified as major cells responsible for mechanotransduction; however, the mechanism underlying the response of bone to mechanical unloading remains poorly understood. In this study, we found that mechanical unloading of wildtype mice caused decrease of Wnt/β-catenin signaling activity accompanied by upregulation of Sost. To further analyze the causal relationship among these events, Sost gene targeting mice were generated. We showed that sclerostin selectively inhibited Wnt/β-catenin in vivo, and sclerostin suppressed the activity of osteoblast and viability of osteoblasts and osteocytes. Interestingly, Sost−/− mice were resistant to mechanical unloading-induced bone loss. Reduction in bone formation in response to unloading was also abrogated in the mutant mice. Moreover, in contrast to wildtype mice, Wnt/β-catenin signaling was not altered by unloading in Sost−/− mice. Those data implied that sclerostin played an essential role in mediating bone response to mechanical unloading, likely through Wnt/β-catenin signaling. Our findings also indicated sclerostin is a promising target for preventing disuse osteoporosis.
Use of FTIR Spectroscopic Imaging to Identify Parameters Associated With Fragility Fracture
Authors: Gourion-Arsiquaud Samuel , Faibish Dan , Myers Elizabeth , Spevak Lyudmila , Compston Juliet , Hodsman Anthony , Shane Elizabeth , Recker Robert R , Boskey Elizabeth R , Boskey Adele L
Published: May 2009

BMD does not entirely explain an individual's risk of fracture. The purpose of this study was to assess whether specific differences in spatially resolved bone composition also contribute to fracture risk. These differences were assessed using Fourier transform infrared spectroscopic imaging (FTIRI) and analyzed through multiple logistic regression. Models were constructed to determine whether FTIRI measured parameters describing mineral content, mineral crystal size and perfection, and collagen maturity were associated with fracture. Cortical and cancellous bone were independently evaluated in iliac crest biopsies from 54 women (32 with fractures, 22 without) who had significantly different spine but not hip BMDs and ranged in age from 30 to 83 yr. The parameters that were significantly associated with fracture in the model were cortical and cancellous collagen maturity (increased with increased fracture risk), cortical mineral/matrix ratio (higher with increased fracture risk), and cancellous crystallinity (increased with increased fracture risk). As expected, because of its correlation with cortical but not cancellous bone density, hip BMD was significantly associated with fracture risk in the cortical but not the cancellous model. This research suggests that additional parameters associated with fracture risk should be targeted for therapies for osteoporosis.
New Variants in the Enpp1 and Ptpn6 Genes Cause Low BMD, Crystal-Related Arthropathy, and Vascular Calcification
Authors: Babij Philip , Roudier Martine , Graves Tom , Han Chun-Ya E , Chhoa Mark , Li Chi-Ming , Juan Todd , Morony Sean , Grisanti Mario , Li Xiaodong , Yu Longchuan , Dwyer Denise , Lloyd David J , Bass Michael B , Richards William G , Ebeling Christine , Amato Julie , Carlson George
Published: May 2009

A large genome-wide, recessive, N-ethyl-N-nitrosourea (ENU)-induced mutagenesis screen was performed on a mixed C57BL/6J and C3H.SW-H2/SnJ mouse background to identify genes regulating bone mass. Approximately 6500 male and female G3 hybrid mice were phenotyped at 8 and 10 wk of age by DXA analysis for evidence of changes in unadjusted or body weight–adjusted BMD or BMC. Phenodeviant lines were identified based on statistical criteria that included a false discovery rate (FDR) <20% and Z-score >2.8. Genome-wide mapping scans were initiated on 22 lines, with evidence of high or low BMD or BMC that deviated by approximately −30% to +50% from the means. Several lines were discontinued as showing lack of heritability, but two heritable lines were identified with narrow chromosomal regions that allowed sequencing of potential mutant candidate genes. Novel mutations were identified in the Enpp1 (C397S) gene on chromosome 10 (line 4482) and the Ptpn6 (I482F) gene on chromosome 6 (line 4489) that were both associated with low bone mass. In addition, the phenotype of the Enpp1 mice showed a striking joint disease and calcification of blood vessels including the aorta, myocardium, and renal arteries and capillaries. These results support a role for the Enpp1 gene in the pathogenesis associated with mineralization of articular cartilage and vascular calcification. This work confirms the utility of the chemical mutagenesis approach for identification of potential disease genes and confirms the role of Enpp1 and Ptpn6 in regulating mineralization and skeletal bone mass.
Dose-Dependent Effects of Runx2 on Bone Development
Authors: Zhang Shiqin , Xiao Zhousheng , Luo Junming , He Nan , Mahlios Josh , Quarles L Darryl
Published: May 2009

Runx2 controls the commitment of mesenchymal cells to the osteoblastic lineage. Distinct promoters, designated P1 and P2, give rise to functionally similar Runx2-II and Runx2-I isoforms. We postulate that this dual promoter gene structure permits temporal and spatial adjustments in the amount of Runx2 isoforms necessary for optimal bone development. To evaluate the gene dose-dependent effect of Runx2 isoforms on bone development, we intercrossed selective Runx2-II+/− with nonselective Runx2-II+/−/Runx2-I+/− mice to create compound mutant mice: Runx2-II+/−, Runx2-II+/−/Runx2-I+/−, Runx2-II−/−, Runx2-II−/−/Runx2-I+/−, Runx2-II−/−/Runx2-I−/−. Analysis of the different Runx2-deficient genotypes showed gene dose-dependent differences in the level of expression of the Runx2 isoforms. In addition, we found that Runx2-I is predominately expressed in the perichondrium and proliferating chondrocytes, whereas Runx2-II is expressed in hypertrophic chondrocytes and metaphyseal osteoblasts. Newborn mice showed impaired development of a mineralized skeleton, bone length, and widening of the hypertrophic zone that were proportionate to the reduction in total Runx2 protein expression. Osteoblast differentiation ex vivo was also proportionate to total amount of Runx2 expression that correlated with reduced Runx2 binding to the osteocalcin promoter by quantitative chromatin immunoprecipitation analysis. Functional analysis of P1 and P2 promoters showed differential regulation of the two promoters in osteoblastic cell lines. These findings support the possibility that the total amount of Runx2 derived from two isoforms and the P1 and P2 promoters, by regulating the time, place, and amount of Runx2 in response to changing environmental cues, impacts on bone development.
Effect of Adherence on Lifetime Fractures in Osteoporotic Women Treated With Daily and Weekly Bisphosphonates
Authors: Danese Mark D. , Badamgarav Enkhe , Bauer Douglas C.
Published: May 2009

Patients miss doses of their osteoporosis medications, or stop taking them altogether, for a variety of reasons. Whereas the reasons have been well-studied, their consequences, at the population level, have not. The goal of this study was to estimate the number of fractures that could be prevented with optimal adherence compared with usual adherence to daily and weekly bisphosphonates in the United States (US). We developed a simulation of adherence to bisphosphonate therapy in the US. The model samples women by age and BMD from nationally representative US distributions, and tracks them over time assuming they are treated with a daily or weekly bisphosphonate. The model simulates two adherence scenarios: usual adherence and optimal adherence. The differences in fracture rates between these scenarios, as well as the medication and fracture costs, are estimated with the model. Approximately 258 (95% interval, 194–324) lifetime fractures can be prevented with optimal adherence per 1,000 bisphosphonate-treated women. For optimal adherence, these results translate to an additional lifetime medication cost of $3,800 and a lifetime savings in fracture-related costs of $2,100, for an expected net cost of $1,700 (95% interval, −$4,100 to $3,300) per woman over her lifetime. These results suggest that in patients taking daily or weekly bisphosphonate therapy, a substantial number of fractures occur that are attributable to less than optimal adherence. These results show that there is implicit value to improving adherence, both from a financial and clinical perspective.
Meta-Analysis of the Effect of the Acid-Ash Hypothesis of Osteoporosis on Calcium Balance
Authors: Fenton Tanis R. , Lyon Andrew W. , Eliasziw Michael , Tough Suzanne C. , Hanley David A.
Published: May 2009

The acid-ash hypothesis posits that protein and grain foods, with a low potassium intake, produce a diet acid load, net acid excretion (NAE), increased urine calcium, and release of calcium from the skeleton, leading to osteoporosis. The objectives of this meta-analysis were to assess the effect of changes in NAE, by manipulation of healthy adult subjects' acid-base intakes, on urine calcium, calcium balance, and a marker of bone metabolism, N-telopeptides. This meta-analysis was limited to studies that used superior methodological quality for the study of calcium metabolism. We systematically searched the literature and included studies if subjects were randomized to the interventions and followed the recommendations of the Institute of Medicine's Panel on Calcium and Related Nutrients for calcium studies. Five of 16 studies met the inclusion criteria. The studies altered the amount and/or type of protein. Despite a significant linear relationship between an increase in NAE and urinary calcium (p < 0.0001), there was no relationship between a change of NAE and a change of calcium balance (p = 0.38; power = 94%). There was no relationship between a change of NAE and a change in the marker of bone metabolism, N-telopeptides (p = 0.95). In conclusion, this meta-analysis does not support the concept that the calciuria associated with higher NAE reflects a net loss of whole body calcium. There is no evidence from superior quality balance studies that increasing the diet acid load promotes skeletal bone mineral loss or osteoporosis. Changes of urine calcium do not accurately represent calcium balance. Promotion of the “alkaline diet” to prevent calcium loss is not justified.
Klotho Variants and Chronic Hemodialysis Mortality
Authors: Friedman David J. , Afkarian Maryam , Tamez Hector , Bhan Ishir , Isakova Tamara , Wolf Myles , Ankers Elizabeth , Ye Jun , Tonelli Marcello , Zoccali Carmine , Kuro-o Makoto , Moe Orson , Karumanchi S. Ananth , Thadhani Ravi
Published: May 2009

Patients with end-stage renal disease (ESRD) suffer exceptionally high mortality rates in their first year of chronic hemodialysis. Both vitamin D and fibroblast growth factor (FGF)-23 levels correlate with survival in these patients. Klotho is a protein in the vitamin D/FGF-23 signaling pathway that has been linked with accelerated aging and early mortality in animal models. We therefore hypothesized that genetic variation in the Klotho gene might be associated with survival in subjects with ESRD. We tested the association between 12 single nucleotide polymorphisms (SNPs) in the Klotho gene and mortality in a cohort of ESRD patients during their first year on hemodialysis (n = 1307 white and Asian). We found a significant association between the CC genotype of one tag SNP, rs577912, and increased risk for 1-yr mortality (RR, 1.76; 95% CI, 1.19–2.59; p = 0.003). This effect was even more marked among patients who were not treated with activated vitamin D supplementation (HR, 2.51; 95% CI, 1.18–5.34; p = 0.005). In lymphoblastoid cell lines derived from HapMap subjects, the CC genotype was associated with a 16–21% lower Klotho expression compared with the AA/AC genotype. Our data suggest that a specific Klotho variant (rs577912) is linked to survival in ESRD patients initiating chronic hemodialysis and that therapy with activated vitamin D may modify this risk.
Elastic T-Stress Solutions of Embedded Elliptical Cracks Subjected to Uniaxial and Biaxial Loadings
Authors: Qu J , Wang X
Published: May 2009

The elastic T-stress has been found to be an important parameter in characterizing the near crack tip elastic-plastic stress states of 2-D and 3-D crack problems. In addition to the J-integral, the T-stress provides an effective two-parameter characterization of 2-D and 3-D elastic-plastic crack tip fields in a variety of crack configurations under small scale yielding conditions. Embedded elliptical crack in an infinite solid subjected to uniaxial or biaxial tension conditions represents an excellent model for many engineering components with embedded cracks. Although extensive analyses are available for stress intensity factors (SIFs) for embedded elliptical cracks, to date no analytical T-stress solutions are available. This paper presents the exact close form solutions for elastic T-stress of an embedded elliptical crack in an infinite body under remote uniaxial or biaxial tension. The foundation of the derivation is based on the potential method for three-dimensional elasticity. Solutions of stress components parallel to and perpendicular to the cracked plane are derived first. T-stress is then obtained from the asymptotic stress field near the crack front. Complete solutions of T-stress along the crack front are established. Further, three-dimensional finite element analyses are conducted to verify the derived solutions; excellent agreements are achieved. When combined with the corresponding K or J solutions, these T-stress solutions are suitable for the analysis of constraint effects for embedded elliptical shaped cracks in engineering components.
Calculation of Neutron Fluxes for Radioactive Inventory Assessment of Magnox Power Plant
Authors: Allen DA , Thiruarooran C , Thornton DA , Fletcher AL , Bird AJ , Rycroft S , Wright GA
Published: May 2009

This paper describes the methodology and results of Monte Carlo neutron transport calculations performed to determine the neutron fluxes required for assessments of radioactive inventories of Magnox power plant. Use has been made of existing validated Monte Carlo models of the plant, which have been extended to include details beyond the pressure vessels to the outer surface of the biological shield.
Accelerated Oxidation and Corrosion Testing of Engine Coolants Using a Rotary Pressure Vessel Oxidation Test
Authors: Alverson Fred C. , Balfe Steven L. , Skrobul Anthony P.
Published: May 2009

Today’s modern engines are exposing engine coolants to more severe operating conditions involving higher coolant temperatures, greater heat rejection requirements, greater metal to coolant heat fluxes, higher coolant flow rates, higher cooling system pressures, and slower deaeration. These conditions will have a tendency to accelerate oxidation/thermal degradation, reduce corrosion protection, and shorten coolant life. In efforts to simulate the increased severity in operating conditions, an accelerated oxidation and corrosion test, using a rotary pressure vessel oxidation test, was developed and evaluated to assess the oxidation/thermal stability and corrosion protection of conventional, hybrid, and extended life coolants. The test involves exposing the coolant to a high temperature oxygen rich environment under pressure with six different metal corrosion coupons. The test allows a quantitative assessment of corrosion protection of the coupons and the effects on coolant chemistry. Test results are provided on conventional, hybrid, and extended life coolants. The test has also been found to be a promising predictive tool to screen satisfactory versus unsatisfactory coolant formulations, including recycled coolants.
Thermal and Oxidative Properties of Physiologically Relevant Free Fatty Acids by Dielectric Analysis and Differential Scanning Calorimetry
Authors: Riga Alan T. , Alexander Kenneth S. , Williams Kevin
Published: May 2009

Physiologically relevant fatty acids and related organic acids are basic for human life. The essential fatty acids, linoleic, linolenic, and arachidonic acids, are sourced from vegetable seed oils (corn, sunflower, safflower), and margarines blended with vegetable oils. The functions of these special acids are in the synthesis of prostaglandins and membrane structures. Growth cessation and dermatitis occurs with a deficiency of the fatty acids. A typical therapeutic dosage of the essential fatty acids is up to 10 g per day. The polyunsaturated fatty acids. linoleic (9,12-octadecaidienoic), linolenic (9,12,15-octadecatrienoic), and arachidonic (5,8,11,14-eicosatetraenoic) are referred to as essential fatty acids. They unlike other lipids must be provided by diet. Arachidonic acid can be produced in the body by linoleic acid. This thermal analytical study is to determine fatty acids’ physical transitions [melting] by DSC at low temperatures and their surface properties by low frequency dielectric analysis and relate those properties to the inherent amount of unsaturation in the fatty acids. It is our premise that the degree of unsaturation will affect low temperature melt temperature and electrical properties, e.g., electrical conductivity and complex permittivity. We have observed that the DEA properties of the air-aged liquid fatty acids indicate that the electrical conductivity and complex permittivity can be correlated with the degree of unsaturation. It is our objective to establish a relationship between the amount of unsaturation, number of double bond sites and the electrical properties, complex permittivity, and electrical conductivity.
Effects of Phase Transformations on Fatigue Endurance of a Superelastic NiTi Alloy
Authors: Wu Ming H.
Published: May 2009

It is well known that NiTi shape memory alloys exhibit superelasticity where a large elastic deformation proceeds under a constant stress due to the formation of stress-induced martensite. However, for most commercial NiTi alloys used in medical devices, the materials are processed in such a way that the R-phase transformation is apparently separated from the martensitic transformation. The B2 to R-phase change exhibits a much smaller shape change and a narrower hysteresis than does the B2 to B19′ martensite transformation. Hence, the transformation temperatures as well as the thermomechanical properties associated with the R-phase are much more stable during cyclic deformation when compared to those associated with the B19′martensite. The crystallographic features for both martensitic and R-phase transformations are reviewed, and their effects on the tensile properties and rotating-beam fatigue endurance are studied in the present paper.
The Natural Cement Revival
Authors: Uracius Ken
Published: May 2009

Although lime has long been an important component in masonry construction, experienced masons working on the restoration of historic buildings in the United States cannot help but notice that some American mortars are very different from the traditional lime mortars used in Europe. American mortars, as found in many 19th century commercial, industrial and government buildings, are clearly tougher and more tenacious than the typical lime mortars. While some claimed that this is due to the importation of hydraulic limes from Europe, study of the period's plentiful documentation reveals that natural cement was the most widely used hydraulic binder in its time. This paper retraces key steps in the search for the history of natural cement use in the United States, and in rediscovering its origins, production methods and use. Ultimately, these steps led to the commercial reintroduction of natural cement for use in historic restoration.
Statistical Distribution of Fiber-Reinforced Concrete Beam Test Data
Authors: Bernard E. S. , Xu G. G.
Published: May 2009

Experience in post-crack performance testing of fiber-reinforced concrete (FRC) and shotcrete (FRS) using beams has demonstrated that variability both at first crack and in the post-crack range is high. When variability in performance is high it is important to carefully consider the within-set standard deviation in order to distinguish significant from insignificant differences between sets of data. It is also important to consider the characteristic distribution of results and use an appropriate probability distribution function (PDF) to estimate the standard deviation. The present investigation has sought to identify whether the Normal probability distribution function is the most appropriate model describing variability in cracking and post-crack performance parameters derived using beam tests.
Microencapsulated Clomazone: Formulation Stability, Tank Mix Volatility, and Solvent Effects
Authors: Keifer David W. , Dexter Robin W. , Nicholson Paul , Pepper Robert F.
Published: May 2009

Clomazone is microencapsulated and sold in the U.S. as a dispersion in water, a capsule suspension (CS), under the name Command®®Command is a trademark of FMC Corporation. 3ME herbicide. Our encapsulated formulation reduces the volatility of the active ingredient when it is applied to the soil surface in a typical agricultural spray use. The commercialized formulation was selected from among hundreds of encapsulated formulations for its ability to reliably control volatility. Many of the rejected formulations did not control volatility, and it was only through a careful optimization of the encapsulation process that we came to our selection. As part of our formulation development process, we developed a laboratory volatility assessment method for use in screening formulations. This method determined the volatility following a soil application and normalized the volatility of the encapsulated formulations to that of the older Command 4EC herbicide formulation. Our optimized formulation was introduced to the market in 1996 to control volatility. A sample of the first production batch of commercial clomazone 3CS formulation, which had been stored at room temperature and regularly assessed for ten years, continues to provide excellent control of volatility. This indicates that the capsules have remained intact and functional, and that the proportion of clomazone in the capsule, versus outside, has not changed as the formulation aged. When these capsules are diluted in water, some clomazone slowly diffuses out of the capsules. This release is limited by the water solubility of clomazone. Even for excessive residence times in the spray tank, the volatility from the soil surface increased only slightly and was well within the acceptable range, for dilutions used for agricultural spray application. Improper addition of solvents and surfactants to the formulation can provide a phase where the clomazone is soluble, and this solubility will extract clomazone from the capsules. Under these conditions the volatility of the product increased so that it was similar to an unencapsulated formulation. In contrast, addition of other herbicides or spray additives to the spray tank mix had little impact on the volatility.
New Polymeric Comb Dispersants for Agricultural Formulations: A Comparison of Performance in Pesticide Suspension Concentrates
Authors: Stern Alan J. , Elsik Curtis M.
Published: May 2009

A new family of dispersants for agrochemical suspension concentrate (SC) formulations has been created by reacting an anhydride-bearing resin with a methyl capped polyether amine. The result is a moderate molecular weight graft polyamide, with the desirable “comb” geometry. From this family of materials, four were chosen for comparison to three commercially available benchmark dispersants in several typical pesticide suspension concentrates. The criteria used to compare the new to the old dispersants were: ability to reduce suspension viscosity, zeta potential, syneresis, and tendency of the concentrate to “hardpack.” The study demonstrated that the new dispersants are generally very effective dispersants, but care must be used in selecting the best dispersant/wetting agent combination for a given pesticide formulation.
Thermal and Epithermal Fluence Rate Measurements in Multipurpose Reactors: Application of a Least-Squares Fitting Code RESDET to Obtain Thermal and Epithermal Fluence Rates from Measured Reaction Rates
Authors: Voorbraak W. P. , Freudenreich W. E. , Leendertse G. P. , Aaldijk J. K.
Published: May 2009

A generalized least-squares, two group neutron spectrum adjustment code is presented that uses measured reaction rates of activation foils and thermal and epithermal energy cross-section data to calculate the thermal and epithermal fluence rates in case of well-moderated neutron spectra. The code uses the covariance matrices of the measurements and cross sections to produce the covariance matrix of the calculated thermal and epithermal fluence rates. The report also gives some application examples of the code.
C-Crack Initiation in Quasi-Static and Impact Loading of a Bearing-Grade Silicon Nitride
Authors: Shetty Dinesh K.
Published: May 2009

Silicon nitride balls are used in hybrid precision bearings for a variety of applications. The performance of hybrid bearings is generally superior to all-steel bearings. Two problems, however, have been noted. Large balls of silicon nitride form surface cracks, referred to as C-cracks, during surface finishing or handling. Also, some grades of silicon nitride are more susceptible to cracking than others. This paper describes the results of an experimental study of the critical loads (P¯c) for C-crack initiation in ball-on-plate loading using silicon nitride plates and tungsten carbide balls. Cumulative distribution plots were generated from multiple indentation tests at varying peak loads to define the critical load at 50 % probability of cracking. The critical load exhibited a ductile-brittle transition at a ball radius R*. For RR*, the material response was elastic and the critical load increased linearly with R. The latter behavior is referred to as Auerbach’s law. The material properties that determine the critical loads in each regime were identified using plasticity and fracture theories. In the elastic regime, the Auerbach constant is directly proportional to the fracture surface energy (γ) or square of the fracture toughness (KIc). The results of the quasi-static tests were employed to predict critical velocities (vc) and drop heights (hc) for C-crack initiation in ball-on-plate and ball-on-ball impact using a general dynamic analysis. The predictions were accurate in the elastic regime (R>R*), the situation most likely to be encountered in practice. It is shown that the material resistance to C-cracking and the maximum force generated in impact can be plotted on figures that are useful as guides in both material selection and handling of silicon nitride balls.
Multi-Scale Approach to the Fatigue Crack Propagation in High-Strength Pearlitic Steel Wires
Authors: Toribio J. , González B. , Matos J. C. , Ayaso F. J.
Published: May 2009

This paper deals with the influence of the manufacturing process on the fatigue behavior of pearlitic steels with different degrees of cold drawing. The fatigue crack growth rate (da/dN) is related to the stress intensity range (ΔK) by means a compliance method to evaluate the crack depth a in the samples at any instant during the tests. The analysis is focused on the Region II (Paris) of the fatigue behavior in which da/dN=C(ΔK)m, measuring the constants (C and m) for the different degrees of drawing. From the engineering point of view, the manufacturing process by cold drawing improves the fatigue behavior of the steels, since the fatigue crack growth rate decreases as the strain hardening level in the material increases. In particular, the coefficient m (slope of the Paris Law) remains almost constant and independent of the drawing degree, whereas the constant C decreases as the drawing degree rises. The paper focuses on the relationship between the pearlitic microstructure of the steels (progressively oriented as a consequence of the manufacturing process by cold drawing) and the macroscopic fatigue behavior. To this end, a detailed metallographic analysis was performed on the fatigue crack propagation path after cutting and polishing on a plane perpendicular to the crack front. It is seen that the fatigue crack growth path presents certain roughness at the microscopic level, such a roughness being related to the pearlitic colony boundaries more than to the ferrite/cementite lamellae interfaces.
Gas-Jet Quenching
Authors: Stratton Paul
Published: May 2009

It has been suggested that gas quenching of a single component or single layers of components that have been heated in vacuum or conventional atmosphere furnaces can achieve higher quenching rates than those possible with conventional multi-component gas quenching. Such treatments could meet the need for a clean, non-toxic quenching medium that leaves no residues to be removed after processing. The processing of single components gives the operator complete control of quenching intensity, both locally and overall. Moreover, the quenching rate may be changed during the quenching cycle. Extensive computational fluid dynamics modeling of cooling using nitrogen jets has shown that an array of high velocity gas jets close to the surface of a part can cool it at a speed similar to oil. The optimum conditions were: an approximately uniform nozzle field with the jets four to eight times their own diameter apart, at a distance from the part to be quenched of a quarter of the diameter of the jets; and a jet velocity of 100 m/s (224 mph). When these optimized conditions were applied to an idealized gear form, the model suggested that it would be fully hardened if a nitrogen/hydrogen mixture was used.Calculation indicated that in this type of nozzle field, the part would float between the arrays of jets, eliminating the need to fix it. The model was validated using a physical test rig and was found to give results very close to reality, so it could be used to predict cooling behavior. The test rig was also used to quench carburized gear blanks. The hardness profiles produced by quenching in different gas mixtures were compared to those from oil quenched samples, the results confirming the original modeling.
A Human Factors Evaluation of Stethoscopes
Authors: Van Houten Curtis M. , Van Houten Joni M. , Latman Neal S.
Published: May 2009

Background: The need to hear sounds of the human body is important in health care. The stethoscope was designed to improve practitioner’s method of “immediate auscultation.” The purpose of this study was to evaluate and compare 16 human factor characteristics of two electrically amplified and one standard acoustic stethoscope. Methods: Each subject examined the three stethoscopes by listening to heart sounds of the investigator. After examination, each of the 77 subjects evaluated the stethoscopes by completing a questionnaire according to the following categories: sound, comfort, ease of use, and instruction manuals. Subjects ranged in age from 18 to 67 years, with 51 % of the subjects having prior experience with stethoscopes. Results: Both electronically amplified stethoscopes were found to have a significant difference in regard to preference compared with the non-electronically amplified standard stethoscope on all characteristics. No significant differences were found between the two electronically amplified stethoscopes, with the exception of turning the stethoscopes on and off. The average mean ratings of the two electronically amplified stethoscopes were not significantly different. Conclusion: It is clear that electronic amplification was preferred over acoustically amplified sound in this study. As the complexity increases with electronic amplification, the importance of ease-of-use design becomes more important.
Performance Testing of Flashing Installation Methods for Brick Mold and Nonflanged Windows
Authors: Crowder-Moore BJ , Weston TA , Katsaros JD
Published: May 2009

One of the major sources of water intrusion in buildings is through openings in walls caused by windows and other fenestrations, in particular the interface between the window and wall. Numerous flashing products, including self-adhered products, have recently been developed to protect this window-wall interface from moisture intrusion. However, the proper installation of these flashing products is not well understood and installation methods are often misused. Various installation methods have been developed and tested to evaluate performance and ease of installation. While most of the flashing installation development has been focused on residential flanged-style windows, effective installation methods for wood framed “brick mold” windows as well as other “nonflanged” windows have not previously been developed and tested. A series of laboratory wall tests were used to compare the air leakage resistance (ASTM E 283), water leakage resistance (ASTM E 331), and durability (ASTM E 330) of various flashing materials and installation methods. The performance and durability of flashing as installed with round top windows, brick mold windows, and nonflanged windows were tested and evaluated.
Use of Optical Imaging/Image Analysis System for the Quantitative Analysis of Surface Changes Induced by Outdoor Weathering on Sealants
Authors: Wolf AT , Sugiyama S , Lee F
Published: May 2009

Six sealant samples that had been weathered outdoors for 6.8 years in Japan were evaluated using an Optical Imaging/Image Analysis System, Atlas VIEEW™. The specimens were first visually evaluated with aesthetic ratings assigned. These ratings were then used as the reference for the optical image analysis. Image analysis was carried out on sealant images taken under optimized diffuse illumination at a constant illuminance. Two sets of images were captured per specimen, first the weathered surface for deterioration evaluation, and second the unweathered surface as a control (reference) image. Four distinct surface defects are quantifiable in the samples. These are cracking (crazing), visual color change, spatial uniformity of deterioration (due to dirt pick-up and uneven color change, or both), and overall surface texture. Chalking and dirt pick up, as rated visually prior to this evaluation, could not be accurately assessed with the digital imaging technique. The analysis shows that surface cracking and crazing generally can be well characterized using the automated VIEEW™ system. Judging color changes visually is problematic, since cracking and crazing interferes with color judgment. Further investigations are needed to develop an automated surface characterization method for sealants.
Sampling and Analysis of Beryllium at JET: Policy Cost and Impact
Authors: Campling D , Patel B
Published: May 2009

This paper describes the sampling and analysis of beryllium at the Joint European Torus (JET) fusion facility. The current policy requiring 100% personal air sampling (PAS) and taking many surface contamination smears generates 40 000 samples per year. Sample processing, analysis, and the quality assurance (QA) program are described. Costs are summarized to derive a cost per sample of ≈£4.2 ($8). This is economical but as 99.8% of PAS measurements are < 2μg/m3 and the aggregated costs are high, reviewing the policy is justified. The disadvantages of the present strategy, the options for a change of policy, and the role that an accredited real-time analysis instrument could play are discussed. Retrospective analysis affects the machine operating time; a quicker technique would have a significant impact on improving experimental time. The project's experience is that turnaround times of 2–6 h can be routinely achieved for large numbers of samples.
Opportunities for Development of Reference Materials for Beryllium
Authors: Watters RL , Hoover MD , Day GA , Stefaniak AB
Published: May 2009

Reference materials provide the foundation for assessment of analytical chemistry methods, accurate quantification of occupational and environmental exposures, and conduct of in vitro and in vivo toxicology studies for health effects research. Although the National Institute of Standards and Technology (NIST) supplies industry, academia, government, and other users with over 1300 reference materials of the highest quality and metrological value, the number of beryllium reference materials is limited. Currently available beryllium reference materials include standard spectroscopy solutions of beryllium and copper-beryllium alloy in the form of blocks, chips, and rods. Beryllium is present as a trace element in some standard soil-sludge, coal fly ash, and urine reference materials. Beryllium on filter media was available at one time, but is not currently available. A number of opportunities exist for identification and development of needed beryllium reference materials for beryllium-containing ores, beryllium oxide, beryllium metal, beryllium metal-matrix materials, beryllium-containing alloys, and beryllium in biological samples. These opportunities will require multidisciplinary and multi-organizational collaboration. Needed actions include consensus on the relevant chemical and physical forms of beryllium; market analyses of demand for the materials; identification of candidate industrial or laboratory-produced samples of the materials; selection of samples that meet criteria for uniformity, physical form, measured quantities, and continued availability; development of production protocols for collection and preparation of the materials, including adequate provisions for occupational health and environmental protection; incorporation of these materials into a supply, distribution, and cost-recovery infrastructure; and continued feedback and information sharing to ensure that the reference materials are meeting user needs or are modified as necessary. Lessons from other major initiatives for reference materials of lead, silica, and similar materials provide guidance on how to optimize and implement an enhanced program for beryllium reference materials.