bluuebunny/crossref_metadata_2025 huggingface dataset:
Damping Behavior and Mechanism of Graphite and Al2O3 Particles Reinforced Al Matrix Composites
Authors: Zhang Zhong Ming , Hu Bo
Published: March 2011

The graphite and alumina particles reinforced Al matrix composites with graphite up to 5 vol% was prepared by Reciprocating Extrusion (RE). Damping behavior of the composites was measured by dynamic mechanical thermal analyzer. The composites showed more excellent damping Q-1 than pure Al manufactured by RE, and the ambient value was 9.9×10-3 at 5 Hz when the strain amplitude was 8×10-8. The damping behavior of the composites showed slight variation with frequency. The damping capacity increased with increasing of the strain amplitude when the amplitude less than 1.5×10-6, and then became a constant and independent of strain amplitude. The high damping capacity was attributed to micro-sliding interface damping and the dislocation damping.
Bulk Nanocrystalline Cu Produced by High-Energy Ball Milling
Authors: Li Cai Ju , Zhu Xin Kun , Tao Jing Mei , Tang H.L. , Chen T.L.
Published: March 2011

The preparation, mechanical properties, grain size and thermal property of bulk nanocrystalline Cu (BNC-Cu) were investigated in this paper. BNC-Cu can be produced by in situ consolidation of pure Cu powder with high-energy ball milling at room temperature; the average grain sizes of Cu samples decreased with the increasing of ball milling time before 9 h because the grain refining velocity was bigger than the grain growing velocity in this stage. When the ball milling time was beyond 9 h, the average grain size reached a steady minimum value about 27.5 nm. The microhardness of BNC-Cu samples increased with the extending of ball milling time in the first 9 h because the dominating factor was the hardening effect caused by grain refinement and work hardening rather than softening in this stage. BNC-Cu gained its highest microhardness about 1.59GPa when the ball milling time reached 9 h. Subsequently, the microhardness of BNC-Cu slightly fluctuated around this value. Because there were numerous triple grain boundaries and the interaction among different crystal defects in BNC-Cu, BNC-Cu showed outstanding thermal stability when it was annealed in the range of 100°C to 400°C.
Rapid Prototyped Nanocrystalline Copper Parts by Jet Electrodeposition
Authors: Chen Jin Song , Huang Yin Hui , Qiao Bin , Yang Jian Ming , He Yi Qiang
Published: March 2011

The system components and the theory of jet electrodeposition orientated by rapid prototyping (RP) are introduced.The nanocrystalline copper parts with simple shape were fabricated by RP technology. The microstructure evolution of the nanocrystalline Copper layer was examined by means of the Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The results show that the jet electrodeposition can greatly enhance the limited current density, fine crystalline particles and improve deposition quality. The copper deposited layers have nanocrystalline microstructure with average size of 55.6nm. The grain size decreases to 41.4 nm in crystal plane (311).
Microstructure and Mechanical Properties of Mg96Y3Zn1 Alloy Processed by Equal Channel Angular Pressing
Authors: Chen Bin , Lu Chen , Lin Dong Liang , Zeng Xiao Qin
Published: March 2011

The Mg96Y3Zn1 alloy processed by equal channel angular pressing has been investigated. It was found that the Mg96Y3Zn1 alloy processed by ECAP obtained ultrafine grains and exhibits excellent mechanical properties. After ECAP, the average grain size of Mg96Y3Zn1 alloy refined to about 400 nm. The highest strengths with yield strength of 381.45MPa and ultimate tensile strength of 438.33MPa were obtained after 2 passes at 623K. It was found that cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test. As a result, the elongation of alloy is decreased with pass number increasing.
Texture Analysis of Commercial Pure (Grade 3) Ti after Two-Step Severe Plastic Deformation
Authors: Jiang Hong , Xie Chao Ying , Song Jie , Sun Xiao Gang , Zhang Xiao Ning
Published: March 2011

Ultrafine-grained (UFG) commercial pure (CP, grade 3) Ti was produced by two-step severe plastic deformation (eight-pass equal channel angular extrusion (ECAE) at 400 °C and cold rolling (CR) at room temperature (RT)). The crystallographic texture in UFG CP-Ti and coarse-grained (CG) CP-Ti (annealed) after CR at RT are studied by orientation distribution function (ODF) analysis, based on X-ray diffraction. The relationship between the texture components and mechanical properties of UFG CP-Ti after two-step severe plastic deformation (SPD) has been discussed. ODF analysis shows that the main texture components in UFG Ti after CR at RT are (011—5)[11— 01], (011—5)[22—01], (0001)[1—3—43] and (011—3)[21—1—1], while the texture components of (011—3)[1—101—] and (011— 3)[2— 201] appear in CG CP-Ti after CR at RT. The values of Schmid factor for prismatic- slip systems are larger than that for basal slip systems and other slip systems, which is more in favor of the activation of prismatic-. In addition, higher strength of texture in favor of the activation of prismatic- in UFG CP-Ti improves its plasticity.
The Microstructural Studies of Ag/Ni20 Fibre Composites Processed by Severe Plastic Deformation
Authors: Zhang Kun Hua , Wang Chuan Jun , Wen Ming , Guan Wei Ming
Published: March 2011

In present work, Ag/Ni20 fibre composites were prepared by coating extrusion, bunched extrusion, and severe plastic deformation. The microstructure and its evolving rules were investigated by SEM and TEM, and the evolving mechanism of microstructures were also analyzed and discussed. The results showed that: (1) Ni fibre, the enhancement phase of Ag/Ni20 fibre composites, would refine, fracture, and nodularize leading to the mix structure of short fibre and particles duing severe plastic deformation; (2) the (111) of Ag and (111) of Ni could misfit with each other by dislocations and forms half-coherent interface.
Developing Metallic Glass Matrix Composites with In Situ Crystalline Spheres through the Mechanism of Liquid-Liquid Phase Decomposition in Miscibility Gap of the Multicomponent Immiscible Alloys
Authors: He Jie , Chen Shu , Zhao Jiu Zhou
Published: March 2011

The solidification characteristics of the immiscible alloys exhibit a unique opportunity in designing composites with spherical crystalline particles dispersed in the amorphous metal matrix. The multicomponent Al82.87Pb2.5Ni4.88Y7.8Co1.95 immiscible alloy has been designed. The ribbon samples of the multicomponent alloy were prepared by the rapid quenching. The microstructure was characterized and the phase constitution and transformation were studied. The as-quenched samples revealed the Al-based metallic glass matrix is embedded by the spherical crystalline Pb-rich particles. A method has been developed, based on the mechanism of the liquid-liquid phase decomposition in the miscibility gap of the multicomponent immiscible alloy, to produce spherical crystalline particles in the amorphous matrix. The microstructure evolution in the Al-based amorphous matrix composites has been discussed
What is Next for the Genetics of Multiple Sclerosis?
Authors: Ramagopalan Sreeram V. , Dyment David A.
Published: March 2011

We review here our current understanding of the genetic aetiology of the common complex neurological disease multiple sclerosis (MS). The strongest genetic risk factor for MS is the major histocompatibility complex which was identified in the 1970s. In 2011, after a number of genome-wide association studies have been completed and have identified approximately 20 new genes for MS, we ask the question—what is next for the genetics of MS?
HIV and/or AIDS, migrant labour and the experience of God: A practical theological postfoundationalist approach
Authors: August Keith , Müller Julian C.
Published: March 2011

Migrant workers in the Deciduous Fruit Industry are part of the marginalised communities in South Africa who have been severely affected by HIV and/or AIDS. A postfoundationalist approach and the Seven Movements proposed by Müller were traced to present the research undertaken amongst migrant workers with HIV or AIDS. The practical theological investigation was developed from the praxis of HIV and AIDS and the question that it aimed to answer was: ‘What is the experience of God in the lives of persons affected by or infected with HIV/AIDS?’ Whilst it is understood that Christian belief has its own, exclusive integrity, if it is to be valid, it should be able to incorporate the different dimensions of our modern practice to give it the maximum level of meaning and significance.
Approximate Quantum and Acoustic Cloaking
Authors: Greenleaf Allan , Kurylev Yaroslav , Lassas Matti , Uhlmann Gunther
Published: March 2011

For any

E\ge 0

, we construct a sequence of bounded potentials

V^E_{n},\, n\in\Bbb N

, supported in {an annular region

B_{out}\setminus B_{inn}\subset\Bbb R ^3

,} which act as approximate cloaks for solutions of Schrödinger's equation at energy

E

: For any potential

V_0\in L^\infty(B_{inn})

{such that

E

is not a Neumann eigenvalue of

-\Delta+V_0

in

B_{inn}

}, the scattering amplitudes

a_{V_0+V_n^E}(E,\theta,\omega)\to 0

as

n\to\infty

. The

V^E_{ n}

thus not only form a family of approximately transparent potentials, but also function as approximate invisibility cloaks in quantum mechanics. {On the other hand, for

E

close to interior eigenvalues, resonances develop and there exist
almost trapped states
concentrated in

B_{inn}

.} We derive the

V_n^E

from singular, anisotropic transformation optics-based cloaks by a de-anisotropization procedure, which we call \emph{isotropic transformation optics}. This technique uses truncation, inverse homogenization and spectral theory to produce nonsingular, isotropic approximate cloaks. As an intermediate step, we also obtain approximate cloaking for a general class of equations including the acoustic equation.
On the Removal of Finite Discrete Spectrum by Coefficient Stripping
Authors: Simon Barry
Published: March 2011

We prove for a large class of operators,

J

, including block Jacobi matrices, if

\sigma(J) \setminus [\alpha,\beta]

is a finite set, each point of which is an eigenvalue of finite multiplicity, then a finite coefficient stripped,

J_N

, has

\sigma(J_N)\subset [\alpha,\beta]

. We use an abstract Dirichlet decoupling.
Geometrical Versions of improved Berezin–Li–Yau Inequalities
Authors: Geisinger Leander , Laptev Ari , Weidl Timo
Published: March 2011

We study the eigenvalues of the Dirichlet Laplace operator on an arbitrary bounded, open set in

\mathbb{R}^d

,

d \geq 2

. In particular, we derive upper bounds on Riesz means of order

\sigma \geq 3/2

, that improve the sharp Berezin inequality by a negative second term. This remainder term depends on geometric properties of the boundary of the set and reflects the correct order of growth in the semi-classical limit.

Under certain geometric conditions these results imply new lower bounds on individual eigenvalues, which improve the Li–Yau inequality.
An Inexpensive and Simple Method to Demonstrate Soil Water and Nutrient Flow
Authors: Nichols K. A. , Samson‐Liebig S.
Published: March 2011

Soil quality, soil health, and soil sustainability are concepts that are being widely used but are difficult to define and illustrate, especially to a non‐technical audience. The objectives of this manuscript were to develop simple and inexpensive methodologies to both qualitatively and quantitatively estimate water infiltration rates (IR), water‐holding capacity at saturation (WHCs), and potential nitrate‐nitrogen (NO3–N) loss and to test the accuracy and precision of these methods. Complete details for how to assemble the appropriate supplies and conduct the measurements are provided, but for demonstrative purposes these methods do not need to be followed in detail, particularly using the various equations to get quantitative values. In the field and classroom, these demonstrations have been well received by non‐technical and technical audiences and have been performed by request as well as incorporated into agronomy classes for high school and college students and training for agriculture educators. In the laboratory, these methods were tested on 10 benchmark soils and values were compared with each other and soil aggregation as measured by dry soil aggregate distribution and water stability. In these benchmark soils, IR and WHCs increased with a reduction in soil disturbance and more continuous plant cover due to diverse crop rotation and perennials while NO3–N loss was highest in soils with synthetic fertilizer inputs, little plant cover, and more soil disturbance. These results indicate the methodologies outlined here may be used to demonstrate agroecosystem management's impact on soil health.
Examining Whether Learning Space Affects the Retention of Experiential Knowledge
Authors: Montgomery Robert A. , Millenbah Kelly F.
Published: March 2011

Experiential learning describes structured educational opportunities that allow students to physically interact with the course material. This pedagogical technique promotes critical thinking, decision making, problem solving, and increases the retention of knowledge. Given that experiential learning can be employed in a variety of learning spaces (e.g., labs, lecture halls, and outdoor classrooms) we question whether there exists variation in students’ retention of experiential knowledge by learning space. Using an experiential knot‐tying tutorial we tested whether natural resource students perform better in an outdoor learning space versus an indoor classroom. Our results demonstrate that students in the outdoor learning space learned significantly better than those in the indoor classroom following the initial tutorial. However, 30 and 65 days after the experiential tutorial there was no difference in the retention of knowledge between groups. Furthermore, no covariates considered (classroom type, prior experience, age, sex, or GPA) in our longitudinal analysis affected the retention of experiential knowledge. Although, this analysis determined that student retention of certain experiential knowledge is improved, at least initially, when learned in an applied outdoor setting, the overall lack of knowledge retention, regardless of learning space, highlights the importance of repeated opportunities to interact with course material.
Factors Affecting Persistence of Undergraduate Students in a Fisheries and Wildlife Program: Transfer Students
Authors: Wolter Bjørn H. K. , Millenbah Kelly F. , Montgomery Robert A. , Schneider James W.
Published: March 2011

Transfer students are of recognized importance to postsecondary education and every year feed thousands of students into natural resources programs across America. This influx of students can have a sustaining effect on many academic programs, including fisheries and wildlife programs, which are suffering from a nation‐wide decrease in interest and declining enrollment. In this pilot study, we conducted face‐to‐face interviews with students who transferred into a fisheries and wildlife program at a large Midwestern university. We asked 13 questions related to their experiences to better understand student reasons for transferring into, and staying in, a fisheries and wildlife program. Programmatic experience was cited most often by transfer students as their reason for persisting in the program. Students acknowledged the importance of a sense of belonging to a community of scholars as critical to their choice of program; this notion was influenced by parameters such as class size, student–faculty relationships, and peer interactions. Other important characteristics of program selection for transfer students included an ability to be engaged in hands‐on activities (e.g., field courses and undergraduate research experiences) and the desire to engage in a career rather than just a job (i.e., students felt passionate about the work they were doing). Using information generated from this study, other natural resources programs may be better poised to attract and retain transfer students to their programs.
Dehydration of the stratosphere
Authors: Schoeberl M. , Dessler A.
Published: March 2011

Abstract. Domain filling, forward trajectory calculations are used to examine the global dehydration processes that control stratospheric water vapor. As with most Lagrangian models of this type, water vapor is instantaneously removed from the parcel to keep the relative humidity with respect to ice from exceeding saturation or a specified super-saturation value. We also test a simple parameterization of stratospheric convective moistening through ice lofting and the effect of gravity waves as a mechanism that can augment dehydration. Comparing diabatic and kinematic trajectories, we find, in agreement with previous authors, that the additional transport due to the vertical velocity "noise" in the kinematic calculation creates too dry a stratosphere and a too diffuse a water-vapor tape recorder signal compared observations. The diabatic simulations, on the other hand, produce stratospheric water vapor mixing ratios very close to that observed by Aura's Microwave Limb Sounder. Convective moistening, which will increases stratospheric HDO, also increases stratospheric water vapor while gravity waves do the opposite. We find that while the Tropical West Pacific is the dominant dehydration location, dehydration over Tropical South America is also important. Antarctica also makes a contribution to the overall stratospheric water vapor budget by releasing very dry air into the Southern Hemisphere stratosphere following the break up of the winter vortex.
Diagenetic alterations of amino acids and organic matter in the upper Pearl River Estuary surface sediments
Authors: Zhang J. , Zhang R. , Wu Q. , Xu N.
Published: March 2011

Abstract. The objective of this study was to investigate the sources, diagenetic alterations of, and bacterial contributions to sediment organic matter (OM) in the upper Pearl River Estuary. Sediment analyses were conducted for three size fractions of OM, including coarse particulate OM (CPOM), fine particulate OM (FPOM), and ultrafiltered dissolved OM (UDOM). Results showed that the highest and lowest carbon (C): nitrogen (N) ratios were in CPOM and UDOM, respectively, indicating CPOM was relatively enriched in organic C, whereas FPOM was enriched in N-containing molecules. Distributions of amino acids and their D-isomers among the sediment fractions indicated that the percentage of total N represented by total hydrolysable amino acids, C- and N-normalized yields of total D-amino acids, and C- and N-normalized yields of D-alanine, D-glutamic acid, D-serine could be used as diagenetic indicators of sediment OM. Correlations between the N yields in total D-amino acids and total hydrolysable amino acids, and total N yields suggested that the bacterial N in general reflected the bulk N changes in CPOM, FPOM, and UDOM. Our results demonstrate the crucial role of bacteria as a N source in the terrestrial (soil and vascular plant debris) OM transported by the river.
Climate model bias correction and the role of timescales
Authors: Haerter J. O. , Hagemann S. , Moseley C. , Piani C.
Published: March 2011

Abstract. It is well known that output from climate models cannot be used to force hydrological simulations without some form of preprocessing to remove the existing biases. In principle, statistical bias correction methodologies act on model output so the statistical properties of the corrected data match those of the observations. However, the improvements to the statistical properties of the data are limited to the specific timescale of the fluctuations that are considered. For example, a statistical bias correction methodology for mean daily temperature values might be detrimental to monthly statistics. Also, in applying bias corrections derived from present day to scenario simulations, an assumption is made on the stationarity of the bias over the largest timescales. First, we point out several conditions that have to be fulfilled by model data to make the application of a statistical bias correction meaningful. We then examine the effects of mixing fluctuations on different timescales and suggest an alternative statistical methodology, referred to here as a cascade bias correction method, that eliminates, or greatly reduces, the negative effects.
Copula-based statistical refinement of precipitation in RCM simulations over complex terrain
Authors: Laux P. , Vogl S. , Qiu W. , Knoche H. R. , Kunstmann H.
Published: March 2011

Abstract. This paper presents a new Copula-based method for further downscaling regional climate simulations. It is developed, applied and evaluated for selected stations in the alpine region of Germany. Apart from the common way to use Copulas to model the extreme values, a strategy is proposed which allows to model continous time series. In this paper, we focus on the positive pairs of observed and modelled (RCM) precipitation. As the concept of Copulas requires independent and identically distributed (iid) random variables, meteorological fields are transformed using an ARMA-GARCH time series model. The dependence structures between modelled and observed precipitation are conditioned on the prevailing large-scale weather situation. The impact of the altitude of the stations and their distance to the surrounding modelled grid cells is analyzed. Based on the derived theoretical Copula models, stochastic rainfall simulations are performed, finally allowing for bias corrected and locally refined RCM simulations.
Catchment classification by runoff behaviour with self-organizing maps (SOM)
Authors: Ley R. , Casper M. C. , Hellebrand H. , Merz R.
Published: March 2011

Abstract. Catchments show a wide range of response behaviour, even if they are adjacent. For many purposes it is necessary to characterise and classify them, e.g. for regionalisation, prediction in ungauged catchments, model parameterisation. In this study, we investigate hydrological similarity of catchments with respect to their response behaviour. We analyse more than 8200 event runoff coefficients (ERCs) and flow duration curves of 53 gauged catchments in Rhineland-Palatinate, Germany, for the period from 1993 to 2008, covering a huge variability of weather and runoff conditions. The spatio-temporal variability of event-runoff coefficients and flow duration curves are assumed to represent how different catchments "transform" rainfall into runoff. From the runoff coefficients and flow duration curves we derive 12 signature indices describing various aspects of catchment response behaviour to characterise each catchment. Hydrological similarity of catchments is defined by high similarities of their indices. We identify, analyse and describe hydrologically similar catchments by cluster analysis using Self-Organizing Maps (SOM). As a result of the cluster analysis we get five clusters of similarly behaving catchments where each cluster represents one differentiated class of catchments. As catchment response behaviour is supposed to be dependent on its physiographic and climatic characteristics, we compare groups of catchments clustered by response behaviour with clusters of catchments based on catchment properties. Results show an overlap of 67% between these two pools of clustered catchments which can be improved using the topologic correctness of SOMs.
Atmospheric electrical field decrease during the M = 4.1 Sousel earthquake (Portugal)
Authors: Silva H. G. , Bezzeghoud M. , Reis A. H. , Rosa R. N. , Tlemçani M. , Araújo A. A. , Serrano C. , Borges J. F. , Caldeira B. , Biagi P. F.
Published: March 2011

Abstract. In this paper, we report the observation of a significant decrease of the vertical component of the atmospheric electrical field in the Évora region (Portugal) during the M = 4.1 Sousel earthquake of 27 March 2010. The epicentre of the earthquake was 52 km from the observation site, which falls within the theoretical earthquake preparation radius. A simple interpretation based on hypothetical radon emissions is presented, and future experiments required to elucidate these observations are outlined. To our knowledge, this is the first reported observation of a decrease of the atmospheric electrical field preceding an earthquake.
On the Kalman Filter error covariance collapse into the unstable subspace
Authors: Trevisan A. , Palatella L.
Published: March 2011

Abstract. When the Extended Kalman Filter is applied to a chaotic system, the rank of the error covariance matrices, after a sufficiently large number of iterations, reduces to N+ + N0 where N+ and N0 are the number of positive and null Lyapunov exponents. This is due to the collapse into the unstable and neutral tangent subspace of the solution of the full Extended Kalman Filter. Therefore the solution is the same as the solution obtained by confining the assimilation to the space spanned by the Lyapunov vectors with non-negative Lyapunov exponents. Theoretical arguments and numerical verification are provided to show that the asymptotic state and covariance estimates of the full EKF and of its reduced form, with assimilation in the unstable and neutral subspace (EKF-AUS) are the same. The consequences of these findings on applications of Kalman type Filters to chaotic models are discussed.
Atypical papillary lesions after core needle biopsy and subsequent breast carcinoma
Authors: Khamapirad Tuenchit , Andrews Caitlin , Prueksadee Jenjeera , Leonard Morton , Bonoan-Deomampo Louisea , Ahao Qing , Golardi Natalia , Eltorky Mahmoud A.
Published: March 2011

Background: Papillary lesions of the breast cause diagnostic problem because papillary structures are found in benign and malignant processes. Core needle biopsy is important to make an initial diagnosis, but it still has potential pitfalls. Comparison between core needle biopsy and excisional biopsy can predict the possibility of malignant change in atypical papillary lesions.

Objective: Evaluate the concordance between core needle biopsy and excisional results in atypical papillary lesions of the breast.

Materials and methods: The pathology database of University of Texas Medical Branch at Galveston, USA was searched for patients with atypical papillary lesions at core needle biopsy who subsequently underwent surgical excision. Pathology reports from the excisional biopsies was also examined to assign each case to one of three categories, downgrade to benign papilloma, no change (remained atypical papillary lesion), and upgrade to carcinoma. The mammograms and ultrasounds were reviewed for each case. They characterized the lesions according to multiple imaging criteria.

Results: Twenty-four patients with atypical papillomas at core biopsy subsequently underwent surgical excision. The lesions were downgraded to benign papilloma in 25%, remained atypical papillary lesion in 33%, and upgraded to carcinoma in 42%. On mammographic presentations (n = 23), masses were in 61%, architectural distortion in 4.3%, mass with calcifications in 9%, mass with architectural distortion and calcifications in 4.3%, calcifications alone in 17.4%, and architectural distortion and calcifications in 4.3%. On ultrasound findings (n = 21), solid masses were in 90%, intracystic masses in 10%, peripheral in locations in 81%, and subareolar in location in 19%.

Conclusion: Due to the high upgrade rate of atypical papillary lesions to carcinoma (42%), excision of all atypical papillary lesions with wide excision margin is recommended for cases with pathologic diagnosis of atypical papillary lesion on core-needle biopsy.
A Comparison of Adult Witnesses' Suggestibility Across Various Types of Leading Questions
Authors: Sharman Stefanie J. , Powell Martine B.
Published: March 2011

The current study directly compared witnesses' susceptibility to suggestion across various structures of misleading interview questions. We examined four question structures that varied on numerous dimensions; whether they narrowed the response option to yes or no, whether they included highly specific detail about the witnessed event and whether they presumed the information being suggested to be true. Susceptibility to misinformation was measured by witnesses' responses to the initial interview questions and their responses to subsequent recognition questions. Interview questions that narrowed the response option and contained specific details and questions that encouraged broader responses but presumed certain information were found to be the most harmful. Participants were more likely to agree with the misleading suggestions contained in these question structures—and more likely to falsely report those suggested details at subsequent interview—than misleading suggestions contained in other question structures. The implications are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Puberty, body fat, and breast density in girls of several ethnic groups
Authors: Novotny Rachel , Daida Yihe , Morimoto Yukiko , Shepherd John , Maskarinec Gertraud
Published: March 2011

Objectives:

We examined breast density by dual energy X‐ray absorptiometry (DXA) in relation to pubertal maturation and body fatness among girls of several ethnic groups, which may suggest important risk factors for future breast cancer.

Methods:

Recruiting 113 girls from Kaiser Permanente Hawaii, we determined ethnicity, age at menarche, weight, height; body mass index (BMI), BMI Z‐scores, Tanner breast, and pubic hair pubertal stages (and classified stages for synchrony, thelarche or adrenarche). DXA scans of the whole body provided percent total and segmental body fat; and separate (specially calibrated) breast scans provided breast tissue, total area, and volume (from manual delineation); absolute and percent fibroglandular volume (%FGV, or breast density) were computed. Statistical analysis included correlation, chi‐square tests, ANOVA, and stepwise regression.

Results:

Twenty‐six percent of girls were overweight or obese. Higher BMI was associated with greater breast area, breast volume, FGV, and with lower breast density (P < 0.0001). Breast area, breast volume, and FGV were positively associated with Tanner breast stage (P < 0.001). Breast density increased until Tanner breast Stage 4 but was lower in Stage 5 (P = 0.03). Pubertal thelarche was associated with lower breast density, compared to synchrony or adrenarche (P = 0.03). Girls with higher BMI (P = 0.02), and Asian girls (compared to White, P = 0.04) were more likely to have pubertal thelarche. Determinants of breast density were, in (stepwise regression) order, percent body fat, achieved menarche, BMI Z‐score, Tanner breast stage (non‐linear), and “Other” ethnicity.

Conclusions:

Female adolescent breast density was negatively associated with body fatness and positively associated with menarche. Am.J. Hum. Biol. 2011. © 2011 Wiley‐Liss, Inc.
Association of CHRNA4 polymorphisms with smoking behavior in two populations
Authors: Han Shizhong , Yang Bao‐Zhu , Kranzler Henry R. , Oslin David , Anton Raymond , Gelernter Joel
Published: March 2011

CHRNA4, the gene that encodes the nicotinic acetylcholine receptor α4 subunit, is a potential candidate gene for nicotine dependence (ND). However, studies of the association of CHNRA4 with smoking behavior have shown inconsistent results. Our meta‐analysis of linkage studies of smoking behavior identified a genome‐wide significant linkage of the phenotype maximum number of cigarettes smoked in a 24‐hour period to a region (20q13.12‐q13.32) harboring CHRNA4. This motivated us to examine the association of CHRNA4 with smoking behavior in two independent samples. In this study, we examined five single nucleotide polymorphisms (SNPs) within CHRNA4 and three smoking‐related behaviors: one quantitative trait [cigarettes smoked per day (CPD)], and two binary traits [DSM‐IV diagnosis of ND and dichotomized Fagerstrom test of ND (FTND)], in 1,249 unrelated European‐Americans (EAs) and 1,790 unrelated African‐Americans (AAs). Using the combined sample with sex, age, and race as covariates, the synonymous SNP rs1044394 was significantly associated with ND (P = 0.001) and FTND (P = 0.01). Rs2236196, which has a low correlation with rs1044394, was also significantly associated with CPD (P = 0.003). The pattern of association for these SNPs was similar in AAs and EAs. After correction for multiple testing, the association between rs1044394 and ND in the combined sample remained significant (P = 0.033). In summary, our study supports association between CHRNA4 common variation and ND in AA and EA samples. Additional studies will be necessary to evaluate the role of rare variants at CHRNA4 for ND. © 2011 Wiley‐Liss, Inc.
Neurovascular coupling is impaired in slow walkers: The MOBILIZE Boston Study
Authors: Sorond Farzaneh A. , Kiely Dan K. , Galica Andrew , Moscufo Nicola , Serrador Jorge M. , Iloputaife Ike , Egorova Svetlana , Dell'Oglio Elisa , Meier Dominik S. , Newton Elizabeth , Milberg William P. , Guttmann Charles R. G. , Lipsitz Lewis A.
Published: March 2011

Objective:

Neurovascular coupling may be involved in compensatory mechanisms responsible for preservation of gait speed in elderly people with cerebrovascular disease. Our study examines the association between neurovascular coupling in the middle cerebral artery and gait speed in elderly individuals with impaired cerebral vasoreactivity.

Methods:

Twenty‐two fast and 20 slow walkers in the lowest quartile of cerebral vasoreactivity were recruited from the MOBILIZE Boston Study. Neurovascular coupling was assessed in bilateral middle cerebral arteries by measuring cerebral blood flow during the N‐Back task. Cerebral white matter hyperintensities were measured for each group using magnetic resonance imaging.

Results:

Neurovascular coupling was attenuated in slow compared to fast walkers (2.8%; 95% confidence interval [CI], −0.9 to 6.6 vs 8.2%; 95% CI, 4.7–11.8; p = 0.02). The odds ratio of being a slow walker was 6.4 (95% CI, 1.7–24.9; p = 0.007) if there was a high burden of white matter hyperintensity; however, this risk increased to 14.5 (95% CI, 2.3–91.1; p = 0.004) if neurovascular coupling was also attenuated.

Interpretation:

Our results suggest that intact neurovascular coupling may help preserve mobility in elderly people with cerebral microvascular disease. Ann Neurol 2011;
Detecting Changes in Simulated Events Using Partial‐Interval Recording and Momentary Time Sampling III: Evaluating Sensitivity as a Function of Session Length
Authors: Devine Sherise L. , Rapp John T. , Testa Jennifer R. , Henrickson Marissa L. , Schnerch Gabriel
Published: March 2011

In a series of two studies, we graphed simulated data representing continuous duration recording and continuous frequency recording into ABAB reversal designs depicting small, moderate, and large behavior changes during 10‐min, 30‐min, and 60‐min sessions. Data sets were re‐scored using partial‐interval recording and momentary time sampling with interval sizes set at 10 s, 20 s, 30 s, 1 min, and 2 min. In study 1, we visually inspected converted data for experimental control and compared the conclusion with those from the respective continuous duration recording or continuous frequency recording data to test for false negatives. In study 2, we evaluated the extent to which interval methods that were sensitive to changes in study 1 produced false positives. In part, the results show that momentary time sampling with interval sizes up to 30 s detected a wide range of changes in duration events and frequency events during lengthier observation periods. The practical implications of the findings are briefly discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Cholesterol biosensors based on oxygen sensing alginate‐silica microspheres
Authors: Prasad Janak , Joshi Abhijeet , Jayant Rahul Dev , Srivastava Rohit
Published: March 2011

Cholesterol determination in body is important in diagnosis of diseases like coronary heart disease, arteriosclerosis, diabetes, and obstructive jaundice. This research aims at developing fluorimetric cholesterol biosensors based on self‐assembled mesoporous alginate‐silica (Algilica) microspheres. For preparing the biosensor, Pt‐(II)‐octaethylporphine (PtOEP; oxygen sensitive metalloporphyrin) dye has been loaded in the Algilica microspheres using the solvent‐mediated precipitation method. Cholesterol oxidase (ChOx) was then covalently conjugated to PtOEP/Algilica microspheres using EDC and NHS reagents. PtOEP dye and enzyme encapsulation, activity and stability were then analyzed. Layer‐by‐layer self‐assembly was finally performed using PAH and PSS polyelectrolytes to minimize leaching of the biosensor components. The prepared biosensor exhibited linearity over a range of 0.77–2.5 mM O2(KSV: 0.097/mM of O2) obtained using from Stern–Volmer plots. The biosensor response to standard cholesterol displayed a linear analytical range from 1.25 to 10 mM of cholesterol with regression coefficient of 0.996 (1.25–3.75 mM), 0.976 (1.25–6 mM), and 0.959 (1.25–10 mM) and response time of 10 min. Thus, the prepared cholesterol biosensor shows great potential in the diagnosis of hypercholesterolemia. Biotechnol. Bioeng. 2011;108:2011–2021. © 2011 Wiley Periodicals, Inc.
Effect of oxic and anoxic conditions on nitrous oxide emissions from nitrification and denitrification processes
Authors: Rassamee Varit , Sattayatewa Chakkrid , Pagilla Krishna , Chandran Kartik
Published: March 2011

A lab‐scale sequencing batch reactor fed with real municipal wastewater was used to study nitrous oxide (N2O) emissions from simulated wastewater treatment processes. The experiments were performed under four different controlled conditions as follows: (1) fully aerobic, (2) anoxic–aerobic with high dissolved oxygen (DO) concentration, (3) anoxic–aerobic with low DO concentration, and 4) intermittent aeration. The results indicated that N2O production can occur from both incomplete nitrification and incomplete denitrification. N2O production from denitrification was observed in both aerobic and anoxic phases. However, N2O production from aerobic conditions occurred only when both low DO concentrations and high nitrite concentration existed simultaneously. The magnitude of N2O produced via anoxic denitrification was lower than via oxic denitrification and required the presence of nitrite. Changes in DO, ammonium, and nitrite concentrations influenced the magnitude of N2O production through denitrification. The results also suggested that N2O can be produced from incomplete denitrification and then released to the atmosphere during aeration phase due to air stripping. Therefore, biological nitrogen removal systems should be optimized to promote complete nitrification and denitrification to minimize N2O emissions. Biotechnol. Bioeng. 2011;108:2036–2045. © 2011 Wiley Periodicals, Inc.
Development and analysis of an instrument to assess student understanding of foundational concepts before biochemistry coursework*
Authors: Villafañe Sachel M. , Bailey Cheryl P. , Loertscher Jennifer , Minderhout Vicky , Lewis Jennifer E.
Published: March 2011

Biochemistry is a challenging subject because student learning depends on the application of previously learned concepts from general chemistry and biology to new, biological contexts. This article describes the development of a multiple‐choice instrument intended to measure five concepts from general chemistry and three from biology that are considered prerequisite for biochemistry learning. This instrument is specifically designed with a factor structure that includes three multiple‐choice items for each of the eight concepts and the most common incorrect ideas that students could have as distractors. It can be used as a pretest to identify students' incorrect ideas about those concepts and to determine if instruction helps students overcome those incorrect ideas when used as a posttest. Results from a confirmatory factor analysis support a very good fit for an eight‐factor solution. This manuscript represents a report on the current state of instrument development. We seek to share our methods and instrument design principles with the broader community. Biochemistry and Molecular Biology Education Vol. 39, No. 2, pp. 102–109, 2011
Eukaryotic cell panorama
Authors: Goodsell David S.
Published: March 2011

Diverse biological data may be used to create illustrations of molecules in their cellular context. This report describes the scientific results that support an illustration of a eukaryotic cell, enlarged by one million times to show the distribution and arrangement of macromolecules. The panoramic cross section includes eight panels that extend from the nucleus to the cell surface, showing the process of protein synthesis and export. Results from biochemistry, electron microscopy, NMR spectroscopy and x‐ray crystallography were used to create the image. Biochemistry and Molecular Biology Education Vol. 39, No. 2, pp. 91–101, 2011
Countering negative country of origin effects using imagery processing
Authors: Martin Brett A.S. , Lee Michael Shyue Wai , Lacey Charlotte
Published: March 2011

A favorable product country of origin (e.g., an automobile made in Germany) is often considered an asset by marketers. Yet a challenge in today's competitive environment is how marketers of products from less favorably regarded countries can counter negative country of origin perceptions. Three studies investigate how mental imagery can be used to reduce the effects of negative country of origin stereotypes. Study 1 reveals that participants exposed to country of origin information exhibit automatic stereotype activation. Study 2 shows that self‐focused counterstereotypical mental imagery (relative to other‐focused mental imagery) significantly inhibits the automatic activation of negative country of origin stereotypes. Study 3 shows that this lessening of automatic negative associations persists when measured one day later. The results offer important implications for marketing theory and practice. Copyright © 2011 John Wiley & Sons, Ltd.
Photocatalytic Reduction of Nitro Compounds Using TiO2 Photocatalyst by UV and Vis Dye‐sensitized Systems
Authors: Chen Shifu , Zhang Huaye , Yu Xiaoling , Liu Wei
Published: March 2011

Nitro‐aromatic compounds can be photocatalytically reduced into the corresponding amine‐aromatic compounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye‐sensitized systems. In the UV/TiO2/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO2/dye‐sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% of p‐nitrotoluene could be photocatalytically reduced into p‐toluidine. In the Vis/TiO2/dye‐sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols. At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.
Interaction of Caffeine with Bovine Serum Albumin: Determination of Binding Constants and the Binding Site by Spectroscopic Methods
Authors: Wu Qiong , Jiang Fenglei , Li Chaohong , Hu Yanjun , Liu Yi
Published: March 2011

The interaction of caffeine with bovine serum albumin (BSA) under physiological condition was investigated by fluorescence, UV‐vis absorption and circular dichroism (CD) spectroscopy. Fluorescence data revealed that the fluorescence quenching of BSA by caffeine was a result of the formation of BSA‐caffeine complex. The binding constants Ka at different temperatures and corresponding thermodynamic parameters ΔH, ΔG and ΔS were calculated. The spectroscopic measurements and the thermodynamic parameters suggested that van der Waals interaction and hydrogen bonds were the predominant intermolecular forces to stabilize the complex. The conformational change of BSA induced by caffeine has been analyzed by means of CD and synchronous fluorescence spectroscopy. Furthermore, it is observed from the probe of competitive experiments that the binding location of caffeine with BSA could be the same as warfarin binding site I of BSA, which was also revealed by fluorescence anisotropy.
Synthesis, Crystal Structure and Vibrational Spectroscopy of NH4 [Co(NH3)5 (H2O)][B4O5 (OH)4]2·6H2O
Authors: Lin Dan , You Xiaoyan , Zhu Lixia , Xiao Qin
Published: March 2011

A novel hydrated cobalt tetraborate complex NH4[Co(NH3)5(H2O)][B4O5(OH)4]2·6H2O, was synthesized by the reaction of NH4‐borate aqueous with CoCl2 and its structure was determined by single crystal X‐ray diffraction. The crystal system of this complex is orthorhombic, the space group is Pnma, and the unit cell parameters are a=1.2901(2) nm, b=1.6817(3) nm, c=1.1368(2) nm, α=β=γ=90°, V=2.4742(8) nm3, and Z=4. This compound contains infinite borate layers constructed from [B4O5(OH)4]2− units via hydrogen bonds. The adjacent polyborate anion layers are further linked together with the octahedral [Co(NH3)5(H2O)]3+ groups through hydrogen bonds to form 3D framework. The groups and guest water molecules are deposited in the empty space of this framework and interact with the layers by extensive hydrogen bonds. Infrared and Raman spectra (4000–400 cm−1) of NH4[Co(NH3)5(H2O)][B4O5(OH)4]2·6H2O were recorded at room temperature and analyzed. Fundamental vibrational modes were identified and band assignments were made. The middle band observed at 575 cm−1 in Raman spectrum is the pulse vibration of [B4O5(OH)4]2−.
First Total Synthesis of (±)‐Puyanin and (±)‐4′‐O‐Methylbonannione
Authors: Zhang Yuheng , Yang Jinhui , Li Hongjun , Jiang Shizhi , Li Yunfeng , Liu Wanyi
Published: March 2011

A facile approach for the first total synthesis of two naturally occurring geranylated flavonoids, (±)‐puyanin (1) and (±)‐4′‐O‐methylbonannione (2) has been obtained with total yields of 27% and 17.8%, respectively. The key steps were regioselective cyclization of geranylated trihydroxychalcone and regioselective geranylation of 2,4,6‐trihydroxyacetophenone.
Magnetically Separable and Versatile Pd/Fe3O4 Catalyst for Efficient Suzuki Cross‐Coupling Reaction and Selective Hydrogenation of Nitroarenes
Authors: Zhang Rongzhao , Liu Jianming , Li Fuwei , Wu Shoufeng , Xia Chungu , Sun Wei
Published: March 2011

Magnetic nanoparticle‐supported Pd/Fe3O4 was readily prepared and proved to be versatile catalyst for efficient Suzuki cross‐coupling reaction, and the reduction of nitroarenes under mild conditions (balloon H2 pressure and room temperature). The catalyst could be conveniently recovered and reused several times with sustained catalytic activity.
Detection of Phthalate Esters in Environmental Water Samples –Comparison of Nylon6 Nanofibers Mat‐based Solid Phase Extraction and Other Conventional Extraction Methods
Authors: Xu Qian , Yin Xueyan , Shen Yanyan , Zhang Niping , Wang Min , Gu Zhongze
Published: March 2011

In this article, a new method for simultaneous determination of six phthalate esters was developed by a combination of electrospun nylon6 nanofibers mat‐based solid phase extraction with high performance liquid chromatography‐ultraviolet detector (HPLC‐UV). The six phthalate esters were dimethyl phthalate (DMP), diethyl phthalate (DEP), butyl benzyl phthalate (BBP), di‐n‐butyl phthalate (DBP), di‐(2‐ethylhexyl) phthalate (DEHP) and dioctyl phthalate (DOP). Under optimized conditions, all target analytes in 50 mL environmental water samples could be completely extracted by 2.5 mg nylon6 nanofibers mat and eluted by 100 µL solvent. Compared with C18 cartridges solid phase extraction, C18 disks solid phase extraction and national standard method (China), nylon6 nanofibers mat‐based solid phase extraction was advantageous in aspects of simple and fast operation, low consumption of extraction materials and organic solvents. The four methods were applied to analysis of environment water samples. All the results indicated that the determination values of target compounds with the proposed method were consistent with C18 cartridges and C18 disks solid phase extraction method, and the new method was better than the national standard method in aspects of recovery, LOD and precision. Therefore, nylon6 nanofibers mat has great potential as a novel material for solid phase extraction.