bluuebunny/crossref_metadata_2025 huggingface dataset:
Early retirement from work among employees with a diagnosis of personality disorder compared to anxiety and depressive disorders
Authors: Korkeila J. , Oksanen T. , Virtanen M. , Salo P. , Nabi H. , Pentti J. , Vahtera J. , Kivimäki M.
Published: June 2010

Objective

Risk of retirement from work before statutory retirement age among employees with personality disorders is unknown.

Method

We used diagnoses of awarded medical rehabilitations and hospitalisations to select two clinical cohorts from a population of 151,618 employees: participants in rehabilitation (total N = 1942, 233 personality disorder, 419 anxiety disorder and 1290 depression cases) and hospitalised patients (N = 1333, 354, 126 and 853, respectively). Early retirement from work was tracked through national registers during a period of 5 years. Cox proportional hazard models were used to examine the association of diagnostic groups with risk of early retirement.

Results

In models adjusted for age, sex and socioeconomic position, the relative risk of early retirement for patients with personality disorders was 3.5-fold (95% CI 2.1 to 5.8) in the rehabilitation cohort and 2.3-fold (95% CI 1.6 to 3.5) in the hospital cohort compared with anxiety disorders. The corresponding hazard ratios of early retirement for personality disorders compared with depressive disorders were 1.1 (95% CI 0.8–1.5) and 1.7 (95% CI 1.4–2.1), respectively.

Conclusions

Personality disorders increase the risk of early retirement at least to an equal extent as depression and more than twice that of anxiety disorders.
Glucose transporter 10 and arterial tortuosity syndrome: The vitamin C connection
Authors: Segade Fernando
Published: June 2010

Arterial Tortuosity Syndrome (ATS) is a heritable disease characterized by twisting and lengthening of the major arteries, hypermobility of the joints, and laxity of skin. ATS is caused by mutations in SLC2A10, encoding Glucose Transporter 10 (GLUT10). The current model of ATS holds that loss of GLUT10 at the nuclear periphery induces a glucose‐dependent increase in Transforming Growth Factor‐β (TGFβ) that stimulates vessel wall cell proliferation. Instead, we propose that GLUT10 transports ascorbate, a cofactor for collagen and elastin hydroxylases, into the secretory pathway. In ATS, loss of GLUT10 results in defective collagen and/or elastin. TGFβ activation represents a secondary response to a defective extracellular matrix.
A strategy to rapidly identify the functional targets of microRNAs by combining bioinformatics and mRNA cytoplasmic/nucleic ratios in culture cells
Authors: Li Jie , Xia Wei , Huang Baochun , Chen Liucun , Su Xueting , Li Shaohua , Wang Fang , Ding Hongmei , Shao Ningsheng
Published: June 2010

MicroRNAs are approximately 22nt non‐coding RNAs that are present in a broad range of multicellular organisms. MicroRNAs play important roles in many biological or pathological processes by regulating the expression of their target genes. The fast and accurate identification of miRNA targets is a bottleneck in the clarification of the function of miRNAs. Here, we established a rapid and accurate strategy to identify miRNA functional target genes by combination of bioinformatic prediction with Cytoplasmic/Nuclear (C/N) ratios of mRNAs. The strategy comprises three steps: bioinformatic prediction, determination of mRNA C/N ratios, and confirmation by Western blotting, and might be suitable to most miRNAs. Our method will make a significant contribution to the study of the biological functions of miRNAs.
A single nucleotide polymorphism in the 3-hydroxy-3-methylglutaryl-coenzyme A reductase gene (HMGCR) influences the serum triacylglycerol relationship with dietary fat and fibre in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk) study
Authors: Freitas Renata N. , Khaw Kay-Tee , Wu Kelvin , Bowman Richard , Jeffery Hannah , Luben Robert , Wareham Nicolas J. , Bingham Sheila A.
Published: June 2010

The objective of the present study was to investigate the influence of the single nucleotide polymorphism (rs17238540) at the 3-hydroxy-3-methylglutaryl-coenzyme A reductase gene (HMGCR) on the relationship between serum lipids and dietary fat and fibre (NSP). FFQ and pyrosequencing were used to assess cross-sectional dietary intake andHMGCRgenotype in a population study with data for serum lipids available. Genotype frequencies and allele distributions for 23 011 participants were: TT 95·65 %, TG 4·29 % and GG 0·06 %; T 97·8 % and G 2·2 %. In regression analyses, the TG+GG group showed a significant positive relationship between TAG and SFA intake (+0·11 (95 % CI 0·02, 0·20) mmol TAG/l;P = 0·017; per 3 % SFA energy increase) while the TT individuals showed no change in the TAG levels related to SFA intake ( − 0·0007 (95 % CI − 0·02, 0·02) mmol TAG/l;P = 0·99). TG+GG individuals showed an inverse relationship between TAG and fibre intake higher ( − 0·14 (95 % CI − 0·22, − 0·05) mmol TAG/l than the TT group ( − 0·04 (95 % CI − 0·06, − 0·02) mmol TAG/l). In both cases the respective coefficient regressions of TAG were different between the genotype groups (Z = 2·27,P = 0·023 for SFA intake; Z = 2·19,P = 0·029 for fibre intake). Individuals carrying the G allele may show a greater response in lower TAG levels with reduced SFA intake and increased fibre intake compared with those homozygous for the T allele. The effectiveness of different dietary interventions to control serum lipids may vary according toHMGCRgenotype.
Presence of alkylresorcinols, potential whole grain biomarkers, in human adipose tissue
Authors: Jansson Erika , Landberg Rikard , Kamal-Eldin Afaf , Wolk Alicja , Vessby Bengt , Åman Per
Published: June 2010

Alkylresorcinols (AR) in plasma samples have been suggested to be short- to medium-term biomarkers of whole grain wheat and rye intake. In the present study, we investigated whether AR are present in human adipose tissues, and if content correlated with long-term whole grain bread intake. Furthermore, we investigated if the relative AR homologue composition reflected what has been found previously in the habitual diet of Swedes. Biopsy samples (10–25 mg) from free-living Swedish women (n 20) were analysed by GC–MS. The mean total AR concentration in the samples was 0·54 (sd 0·35) μg/g, ranging from below limit of quantification ( < 0·08 μg/g) to 1·50 μg/g. Whole grain bread intake was significantly correlated with plasma total AR content (r 0·48, P < 0·05), and the C17 : 0/C21 : 0 ratio was 0·35 (sd 0·24), which is similar to what is found in plasma among free-living subjects consuming a mixed whole grain wheat and rye diet. These results suggest that AR in the adipose tissue should be evaluated as a long-term biomarker of whole grain wheat and rye intake.
Sex differences in lipid and glucose kinetics after ingestion of an acute oral fructose load
Authors: Tran Christel , Jacot-Descombes Delphine , Lecoultre Virgile , Fielding Barbara A. , Carrel Guillaume , Lê Kim-Anne , Schneiter Philippe , Bortolotti Muriel , Frayn Keith N. , Tappy Luc
Published: June 2010

The increase in VLDL TAG concentration after ingestion of a high-fructose diet is more pronounced in men than in pre-menopausal women. We hypothesised that this may be due to a lower fructose-induced stimulation of de novo lipogenesis (DNL) in pre-menopausal women. To evaluate this hypothesis, nine healthy male and nine healthy female subjects were studied after ingestion of oral loads of fructose enriched with 13C6 fructose. Incorporation of 13C into breath CO2, plasma glucose and plasma VLDL palmitate was monitored to evaluate total fructose oxidation, gluconeogenesis and hepatic DNL, respectively. Substrate oxidation was assessed by indirect calorimetry. After 13C fructose ingestion, 44·0 (sd 3·2) % of labelled carbons were recovered in plasma glucose in males v. 41·9 (sd 2·3) % in females (NS), and 42·9 (sd 3·7) % of labelled carbons were recovered in breath CO2 in males v. 43·0 (sd 4·5) % in females (NS), indicating similar gluconeogenesis from fructose and total fructose oxidation in males and females. The area under the curve for 13C VLDL palmitate tracer-to-tracee ratio was four times lower in females (P < 0·05), indicating a lower DNL. Furthermore, lipid oxidation was significantly suppressed in males (by 16·4 (sd 5·2), P < 0·05), but it was not suppressed in females ( − 1·3 (sd 4·7) %). These results support the hypothesis that females may be protected against fructose-induced hypertriglyceridaemia because of a lower stimulation of DNL and a lower suppression of lipid oxidation.
Regulation of adipokine secretion byn-3 fatty acids
Authors: Moreno-Aliaga María J. , Lorente-Cebrián Silvia , Martínez J. Alfredo
Published: June 2010

Obesity leads to several chronic morbidities including type 2 diabetes, dyslipidaemia, atherosclerosis and hypertension, which are major components of the metabolic syndrome. White adipose tissue (WAT) metabolism and WAT-derived factors (fatty acids and adipokines) play an important role in the development of these metabolic disturbances. In fact, dysregulated adipokine secretion from the expanded WAT of obese individuals contributes to the development of systemic low-grade inflammation, insulin resistance and metabolic syndrome. Then-3 PUFA EPA and DHA have been widely reported to have protective effects in a range of chronic inflammatory conditions including obesity. In fact,n-3 PUFA have been shown to ameliorate low-grade inflammation in adipose tissue associated with obesity and up-regulate mitochondrial biogenesis and induce beta-oxidation in WAT in mice. Moreover, the ability ofn-3 PUFA to regulate adipokine gene expression and secretion has been observed bothin vitroandin vivoin rodents and human subjects. The present article reviews: (1) the physiological role of adiponectin, leptin and pre-B cell colony-enhancer factor/visfatin, three adipokines with immune-modulatory properties involved in the regulation of metabolism and insulin sensitivity and (2) the actions ofn-3 PUFA on these adipokines focusing on the underlying mechanisms and the potential relationship with the beneficial effects of these fatty acids on obesity-associated metabolic disorders. It can be concluded that the ability ofn-3 PUFA to improve obesity and insulin resistance conditions partially results from the modulation of WAT metabolism and the secretion of bioactive adipokines including leptin, adiponectin and visfatin.
Gut microbiota in obesity and metabolic disorders
Authors: Sanz Yolanda , Santacruz Arlette , Gauffin Paola
Published: June 2010

Obesity is a major public health issue as it is causally related to several chronic disorders, including type-2 diabetes, CVD and cancer. Novel research shows that the gut microbiota is involved in obesity and metabolic disorders, revealing that obese animal and human subjects have alterations in the composition of the gut microbiota compared to their lean counterparts. Moreover, transplantation of the microbiota of either obese or lean mice influences body weight in the germ-free recipient mice, suggesting that the gut ecosystem is a relevant target for weight management. Indigenous gut microbes may regulate body weight by influencing the host's metabolic, neuroendocrine and immune functions. The intestinal microbiota, as a whole, provides additional metabolic functions and regulates the host's gene expression, improving the ability to extract and store energy from the diet and contributing to body-weight gain. Imbalances in the gut microbiota and increases in plasma lipopolysaccharide may also act as inflammatory factors related to the development of atherosclerosis, insulin resistance and body-weight gain. In contrast, specific probiotics, prebiotics and related metabolites might exert beneficial effects on lipid and glucose metabolism, the production of satiety peptides and the inflammatory tone related to obesity and associated metabolic disorders. This knowledge is contributing to our understanding of how environmental factors influence obesity and associated diseases, providing new opportunities to design improved dietary intervention strategies to manage these disorders.
Mechanisms underlying the immunomodulatory effects of n-3 PUFA
Authors: Yaqoob Parveen
Published: June 2010

The enrichment of immune cell membranes with n-3 PUFA is associated with modulation of immune function. The degree of incorporation of n-3 PUFA (and therefore the impact of dietary n-3 PUFA on immune function) appears to depend on a number of factors including species and age. The mechanisms involved are still largely unclear, but recent work has focused on two areas; lipid rafts and eicosanoids. In vitro studies suggest that lipid rafts could play a role in the immunomodulatory effects of n-3 PUFA, but there is still little information regarding the extent to which membrane microdomains in human lymphocytes are modulated by dietary supplementation. The enrichment of cell membranes with n-3 PUFA also modulates the production of eicosanoids, the full extent of which has not yet been realized; this represents a key area for future research.
Phenotypic variation in a significant spore character in Kudoa (Myxosporea: Multivalvulida) species infecting brain tissue
Authors: BURGER MIEKE A. A. , ADLARD ROBERT D.
Published: June 2010

Some Kudoa species display variations in the number of polar capsules in spores within an individual pseudocyst. Nonetheless, there is usually a dominant morphotype which forms a significant element of diagnosis. In 2007, a Kudoa isolate from whiting (spores with 5 (dominant) or 6 (minor) polar capsules) was characterized by Burger et al. (2007) as being 100% identical in SSU rDNA to Kudoa yasunagai (spores with 7 polar capsules) from a halibut, despite its obvious morphological differences. The authors hypothesized that either SSU rDNA had reached its level of resolution or that the genetic identity revealed conspecificity. To further investigate these hypotheses, SSU and LSU rDNA sequence data were coupled with principal components, correlation, and regression analyses of morphometric data from different kudoid isolates that infect brain tissue to determine the relationships between spore morphotypes and different kudoid isolates. The trends in morphometrics between the spores of particular isolates were so similar that it was concluded that the molecular results did indicate conspecificity rather than SSU reaching its level of resolution. This phenotypic influence on a significant diagnostic character within the Kudoidae has a major impact on the diagnosis of this, and potentially other, pathogenic species.
Trypanosoma melophagium from the sheep ked Melophagus ovinus on the island of St Kilda
Authors: GIBSON W. , PILKINGTON J. G. , PEMBERTON J. M.
Published: June 2010

The sheep ked has been largely eradicated in the UK but persists in the feral Soay sheep of St Kilda in the Outer Hebrides. Sheep keds transmit Trypanosoma melophagium, but parasitaemias are typically cryptic and this trypanosome has not been recorded in the St Kilda sheep. Trypanosomes were detected by PCR in preserved keds and were also found in gut smears from live keds; one infected gut was used to establish the trypanosome in vitro. Examination of the morphology of bloodstream forms from culture confirmed its identity as T. melophagium. Most keds were found to harbour the trypanosome, particularly those collected from lambs. DNA was extracted from preserved keds and from trypanosomes grown in vitro. Sequence analysis of the small subunit ribosomal RNA (SSU rRNA) gene and the spliced leader transcript showed the T. melophagium sequences to be very similar to those from T. theileri. A partial sequence of the ked SSU rRNA gene was also obtained. The close genetic relationship of T. melophagium and T. theileri suggests that T. melophagium represents a lineage of T. theileri that adapted to transmission by sheep keds and hence became a specific parasite of sheep.
Genetic evidence for domestic raccoon dog rabies caused by Arctic-like rabies virus in Inner Mongolia, China
Authors: SHAO X. Q. , YAN X. J. , LUO G. L. , ZHANG H. L. , CHAI X. L. , WANG F. X. , WANG J. K. , ZHAO J. J. , WU W. , CHENG S. P. , YANG F. H. , QIN X. C. , ZHANG Y. Z.
Published: June 2010

An outbreak of rabies affected domestic raccoon dogs on an animal farm in Inner Mongolia, China in 2007. A study was conducted to characterize the aetiological agent and clarify the origin of the rabies virus. Brain tissues were obtained from five rabid raccoon dogs. Viral nucleoprotein antigen was detected in the brain tissues and five rabies viruses were isolated from these rabid animals. Phylogenetic analysis of the N and G gene sequences showed that these isolates were closely related to Arctic-like rabies viruses isolated from the far-eastern region of Russia and South Korea, but distinct from the rabies viruses that are widely distributed in endemic areas in China. Epidemiological data suggested that the likely source of infection was from one wild raccoon dog that was captured and placed in the same type of pen used for domestic raccoon dogs.
Community perceptions of bloody diarrhoea in an urban slum in South Asia: implications for introduction of aShigellavaccine
Authors: ARVELO W. , BLUM L. S. , NAHAR N. , VON SEIDLEIN L. , NAHAR L. , PACK R. P. , BROOKS A. W. , PACH A. , BREIMAN R. F. , LUBY S. P. , RAM P. K.
Published: June 2010

Understanding local perceptions of disease causation could help public health officials improve strategies to prevent bloody diarrhoea. A cross-sectional survey was conducted in Dhaka, Bangladesh to elicit community beliefs about the causes of and prevention strategies for bloody diarrhoea. Between March and June 2003, we interviewed 541 randomly selected respondents. Overall, 507 (93%) respondents perceived that a vaccine could prevent bloody diarrhoea. If a vaccine provided lifetime protection, 445 (83%) respondents stated that they would opt to get the vaccine and would pay a median of $0·05 (range U.S.$0·01–0·15) for it, equivalent to <1% of their median weekly income. There was almost universal perception that an effective vaccine to prevent bloody diarrhoea was highly beneficial and acceptable. While respondents valued a vaccine for prevention of bloody diarrhoea, they were only willing to pay minimally for it. Therefore, achieving a high rate ofShigellavaccine coverage may require subsidy of vaccine purchase.
Selecting the best of the worst: the grammar of Hebrew blends
Authors: Bat-El Outi
Published: June 2010

Blends, also called portmanteau words, are formed by fusing two words into one new word, where internal portions of the base words are often subtracted (one segmental string from the right part of the first word and another from the left part of the second word). For example, the English blendnixonomicshas been formed by combiningnixonandeconomicsand subtracting the stringneco. (For clarity of exposition, blends will be usually represented asnixonomics, where the subtracted material is enclosed in angled brackets and the boundary between the base elements is indicated by ⋅).
Reconsidering [consonantal]
Authors: Hume Elizabeth , Odden David
Published: June 2010

One of the fundamental claims of modern phonology is that generalisations about phonemes are based on a small, universal set of phonetically defined features. The theory of distinctive features is a very powerful idea, insofar as it predicts that sets of phonemes will act together in specific ways within and across languages, allowing the voiceless stops [p t k] to serve as a unified target or trigger class, but ruling out the possibility that [p r y a] will function as a unitary class. Much of the appeal of distinctive features lies in the fact that the rich array of segments and processes encountered in the world's languages can be understood in terms of a very small number of features. Numerous hypotheses have been advanced regarding what that set of features is – see Jakobsonet al. (1952), Chomsky & Halle (1968), Sagey (1990) and Clements & Hume (1995),inter al. The ideal set of features must be rich enough to express phonemic contrasts which actually exist, and must otherwise be capable of capturing generalisations about sound structure. Equally important, a theory of features should be maximally impoverished – it should use the minimum resources necessary to describe languages.
Crime propensity, criminogenic exposure and violent scenario responses: Testing situational action theory in regression and Rasch models
Authors: HAAR DIRK-HINRICH , WIKSTRÖM PER-OLOF H.
Published: June 2010

In this paper, we argue that quantitative empirical research to explain and predict criminal and related behaviour can benefit greatly from explicit theories of action linking individual and contextual factors in the causation of crime. Such theories foster a systematic selection of causal variables for data collection and hypothesis testing instead of a more indiscriminate accumulation of ‘risk factor’ correlates. Moreover, action theory encourages statistical modelling of crime causation beyond the most common linear regression. This paper illustrates both points by estimating two empirical models – a conventional logistic model and a Rasch model – on scenario response data concerning youth violence. The findings of this study show that the extent to which young people indicate a violent response to a provocation is dependent on their (law relevant) morality and ability to exercise self-control as well as the deterrent qualities (monitoring) of the setting.
A broad 660 km discontinuity beneath northeast China revealed by dense regional seismic networks in China
Authors: Wang Baoshan , Niu Fenglin
Published: June 2010

We examined the P wave velocity structure around the 660 km discontinuity at the tip of the subducting Pacific slab beneath northeastern China by forward modeling waveform triplication data. A total of 742 broadband seismograms were recorded by dense regional seismic networks in China from a deep earthquake that occurred near the border of east Russia and northeast China, providing an unprecedented density of ray coverage near the front edge of the subducting Pacific slab. Multiple P waves were observed on single seismograms in the distance range of ∼14°–29°. The P wave triplication shows the following two features: (1) the direct arrival traveling above the 660 km discontinuity (AB branch) extends as far as ∼29°, approximately 6° further than the prediction from velocity model of International Association of Seismology and the Physics of the earth's interior (iasp91); (2) the refracted wave propagating through the lower mantle (CD branch) appears at a distance a few degrees greater than that of the iasp91 synthetics. Forward waveform modeling suggests that they are best explained by a high‐velocity transition zone underlain by a ∼50–70 km thick 660 km discontinuity. The broadened discontinuity is likely caused by multiple phase transitions associated with the dissolutions of olivine and garnet components.
First‐order and numerical analyses of flow and transport in heterogeneous bimodal variably saturated formations
Authors: Russo David
Published: June 2010

Addressed here are bimodal, heterogeneous, variably saturated formations, viewed as mixtures of two populations (background soil and embedded soil) of differing spatial structures. Two distinct cases are considered: In the first case, the texture of the embedded soil is finer than that of the background soil; in the second case, the reverse is true. First‐order, Lagrangian‐stochastic analysis of vadose‐zone transport was used to investigate the combined effect of the texture of the embedded soil and the mean pressure head on solute spread and breakthrough in these formations. The main results of the first‐order analysis suggest that features of solute transport associated with the two different formations exhibit a crossover behavior and that the mean pressure head associated with the crossover may be estimated from the asymptotic macrodispersivities associated with the two formations. The applicability of the results of the first‐order analysis to more realistic conditions was tested with a series of detailed numerical simulations of the flow and transport in three‐dimensional, heterogeneous, bimodal, variably saturated formations; relatively simple, steady state flow and more complicated, transient, nonmonotone flow originating from periodic influx and water uptake by plant roots were considered. For the steady state flows, results of the simulations were in qualitative agreement with the results of the first‐order analysis. For the more realistic flow regime, the results of the simulations suggested that the difference between the responses of the two different bimodal formations might decrease substantially, similar to the situation in steady state flow associated with mean pressure head at which a crossover occurs.
Blazing Angels or Resident Evil? Can Violent Video Games be a Force for Good?
Authors: Ferguson Christopher J.
Published: June 2010

Violent video games have been a source of controversy in the United States and elsewhere for several decades. Considerable concern has been raised in the public and scientific communities about the alleged deleterious effects of violent games. These concerns may coincide with periodic moral panics about media's influence, particularly on youth. This paper argues that the negative effects of violent games have been exaggerated by some elements of the scientific community, fitting with past cycles of media-focused moral panics. By contrast, potential positive effects of violent video game play have been ignored in the debate on violent games. The current paper considers research in several areas, including aggression, but also the nascent research fields of visuospatial cognition, social networking, and use as educational tools. It is argued that the debate on video game violence should be broadened to include both potential negative and positive effects.
Children's Motivations for Video Game Play in the Context of Normal Development
Authors: Olson Cheryl K.
Published: June 2010

Electronic games are now an everyday part of childhood and adolescence. The debate has moved from whether children should play video games to how to maximize potential benefits and to identify and minimize potential harms. To do this, we must understand what motivates children to play electronic games and what needs the games meet. Drawing on a survey of 1,254 middle school children, focus groups with boys and their parents, and findings from other quantitative and qualitative research, the author describes a variety of motivations for video game play (including games with violent content) and how these may vary based on factors such as mood, environment, personality, and developmental stage. The findings are put into the context of normal development, and suggestions are given for parents, educators, and researchers.
Vulnerability to Violent Video Games: A Review and Integration of Personality Research
Authors: Markey Patrick M. , Markey Charlotte N.
Published: June 2010

In this report, past research is reviewed, which suggests that the personality traits of psychoticism and aggressiveness likely moderate the negative effects of violent video games (VVGs). The Five-Factor Model (FFM) of personality is then used as a taxonomy to integrate these findings and examine why these traits are important moderator variables. Analyses suggest that these traits likely moderate the effects of VVGs because they contain the FFM traits neuroticism (+), agreeableness (−), and conscientiousness (−). A spherical model of personality, derived from these three FFM traits, is presented as a method of predicting aggression and hostility after playing VVGs; archival data confirms the predictions derived from this spherical model. Findings from the current research demonstrate the utility of a three-trait spherical model to examine the moderating effects of VVGs and suggest that only some individuals are adversely affected by VVGs and that those who are affected have preexisting dispositions, which make them susceptible to such violent media.
Let the Games Begin: Civic Playing on High-Tech Consoles
Authors: Umaschi Bers Marina
Published: June 2010

The author presents an overview of an emerging field that looks at the impact of video games on civic engagement. Some video games have explicit civics-related content and engage players in simulations of civically related projects, but most others do not. However, research has shown that video game playing engages players in civically oriented experiences that previous research has found to promote civic outcomes in classroom-based programs. These include helping and guiding others; learning about problems in society; exploring social, moral, or ethical issues; organizing groups; and making decisions about how a community, city, or nation should be run.
Fluorescent nanopigments: Quantitative assessment of their quantum yield
Authors: Ferrini R. , Nicolet O. , Huber S. , Zuppiroli L. , Chappellet S. , Lovey C. , Perrenoud J. , Pauchard M.
Published: June 2010

In the last few years, an intense research effort has focused on the synthesis of fluorescent nanopigments for functional inks, light harvesting, tagging, tracing, (bio)labeling, imaging, and lighting applications. Moreover, combined with dielectric matrices, these fluorescent nanoparticles may open the way to the realization of novel optophotonic devices. In particular, due to the large variety of available organic fluorescent dyes, their encapsulation into either an inorganic or an organic host is a very promising approach to synthesize a large palette of new fluorescent nanopigments. However, since the dye encapsulation may affect the fluorescence efficiency, measuring the quantum yield of fluorescent nanopigments is of paramount importance for the development of any connected application. In this article, we present a diffuse reflectance (DR) technique that enables the quantitative assessment of the quantum yield of fluorescent nanoparticles such as zeolite L nanocrystals and poly(methyl methacrylate) nanospheres both loaded with fluorescent perylene molecules. Our method is validated by measuring a well known fluorescence standard and by comparing the results obtained for a model zeolite nanopigment with those provided by an alternative DR technique. Reliable and reproducible quantum yield values are obtained for both low- and high-efficiency fluorescent nanoparticles. Our technique can thus enable systematic and quantitative studies that may yield an important insight in the mechanisms affecting the fluorescence efficiency of a large variety of nanopigments.
Vortex magnetic field mixing with anisometric particles
Authors: Solis Kyle J. , Bell Richard C. , Martin James E.
Published: June 2010

Recently, we reported a vigorous, scale-adaptive mixing technique suitable for microfluidic applications, wherein a suspension of spherical magnetic particles is subjected to a vortex magnetic field, which induces the formation of dynamic particle chains that efficiently stir the solution. Here we explore the dependence of the mixing torque on particle shape, and show that increasing degrees of shape anisometry (i.e., spheres, platelets, rods) give increased mixing torque at the same particle volume fraction. Moreover, all particles, regardless of shape, exhibit similar dependencies of the mixing torque on the vortex field parameters: the torque is maximized in a balanced vortex magnetic field, is proportional to the square of the field strength, and is independent of the field frequency. However, the torque advantage of anisometric particles is somewhat offset by their increased packing volume, which can make the removal of trapped fluid difficult.
Influence of CH4 on the morphology of nanocrystalline diamond films deposited by Ar rich microwave plasma
Authors: Rakha Sobia Allah , Yu Guojun , Cao Jianqing , He Suixia , Zhou Xingtai
Published: June 2010

The influences of the process gases, such as methane and nitrogen concentration on the morphology of nanocrystallites diamond films are assessed. It has been found that the concentration of CH4 in the reactant gases is important to control the morphology of diamond nanocrystallites. The morphology of nanocrystallites changes from granular to rodlike shape by changing methane concentration in Ar/H2/CH4 microwave plasma. The addition of nitrogen is considered to be helpful in the formation of graphite content and for increasing the deposition rate. No considerable changes in the morphology of diamond nanocrystallites were observed by varying nitrogen concentration in the feed gases as observed by scanning electron microscopy. Although Raman spectroscopy indicated that the amount of sp2-bonded carbon increased by the addition of nitrogen in the plasma. The high concentration of methane in the gas mixture due to the presence of argon rich environment is suggested to be responsible for the formation of diamond nanorods.
Variable charge dust acoustic solitary waves in a dusty plasma with a q-nonextensive electron velocity distribution
Authors: Amour Rabia , Tribeche Mouloud
Published: June 2010

A first theoretical work is presented to study variable charge dust acoustic solitons within the theoretical framework of the Tsallis statistical mechanics. Our results reveal that the spatial patterns of the variable charge solitary wave are significantly modified by electron nonextensive effects. In particular, it may be noted that for −1<q<1 (where q stands for the electron nonextensive parameter) the soliton pulse amplitude increases while its width is narrowed as q→1. As the electrons deviate from their thermodynamic equilibrium, the dust grain charge Qd becomes more negative and the dust grains localization (accumulation) less pronounced. The electrons are locally expelled and pushed out of the region of the soliton’s localization. This electron depletion becomes less effective as the electrons evolve far away from their thermal equilibrium. The case q>1 provides qualitatively opposite results: electron nonextensivity makes the solitary structure more spiky. Our results should help in providing a good fit between theoretical and experimental results.
Collective diffusion of colloidal hard rods in smectic liquid crystals: Effect of particle anisotropy
Authors: Patti Alessandro , El Masri Djamel , van Roij René , Dijkstra Marjolein
Published: June 2010

We study the layer-to-layer diffusion in smectic-A liquid crystals of colloidal hard rods with different length-to-diameter ratios using computer simulations. The layered arrangement of the smectic phase yields a hopping-type diffusion due to the presence of permanent barriers and transient cages. Remarkably, we detect stringlike clusters composed of interlayer rods moving cooperatively along the nematic director. Furthermore, we find that the structural relaxation in equilibrium smectic phases shows interesting similarities with that of out-of-equilibrium supercooled liquids, although there the particles are kinetically trapped in transient rather than permanent cages. Additionally, at fixed packing fraction we find that the barrier height increases with increasing particle anisotropy, and hence the dynamics is more heterogeneous and non-Gaussian for longer rods, yielding a lower diffusion coefficient along the nematic director and smaller clusters of interlayer particles that move less cooperatively. At fixed barrier height, the dynamics becomes more non-Gaussian and heterogeneous for longer rods that move more collectively giving rise to a higher diffusion coefficient along the nematic director.
Nonlinear acoustic waves in nonthermal dusty or pair plasmas
Authors: Verheest Frank
Published: June 2010

Using a Sagdeev pseudopotential formalism where nonlinear structures are stationary in a comoving frame, large dust-acoustic solitary waves and double layers have been studied in plasmas with negative cold dust or heavier ions, in the presence of nonthermal electrons and protons/positrons. The existence domain of negative solitary waves is limited by infinite compression of the negative dust or heavy ion species, that of positive solitary waves by the occurrence of positive double layers. These double layers require a sufficient degree of nonthermality of the hot species. There are parameter ranges where both negative and positive solitary structures can occur; sometimes both of the solitary wave type or sometimes one solitary wave and the other a double layer. Great emphasis is placed on the determination of the existence domains in compositional parameter space, with the help of strong analytical results, before typical Sagdeev pseudopotentials and solitary wave profiles are presented. Subject to simple adjustments, these results apply equally to a conjugate plasma model of positive dust or heavy ions, together with nonthermal electrons and protons/positrons.
Effect of particle size on the UV pulsed-laser scribing in computational fluid dynamics-based simulations
Authors: Park Kwan-Woo , Na Suck-Joo
Published: June 2010

A computational model for UV pulsed-laser scribing of silicon target is presented and compared with experimental results. The experiments were performed with a high-power Q-switched diode-pumped solid state laser which was operated at 355 nm. They were conducted on n-type 500 μm thick silicon wafers. The scribing width and depth were measured using scanning electron microscopy. The model takes into account major physics, such as heat transfer, evaporation, multiple reflections, and Rayleigh scattering. It also considers the attenuation and redistribution of laser energy due to Rayleigh scattering. Especially, the influence of the average particle sizes in the model is mainly investigated. Finally, it is shown that the computational model describing the laser scribing of silicon is valid at an average particle size of about 10 nm.
Magnetoresistance and transport properties of CoFeB/MgO granular systems
Authors: Bhutta K. M. , Reiss Günter
Published: June 2010

Magnetoresistance and transport properties of ultrathin multilayers of CoFeB/MgO prepared by rf and dc magnetron sputtering were studied in the temperature range between 15 and 330 K. Due to the magnetic softness of CoFeB, this system offers a potentially high magnetoresistance at comparably low magnetic fields. At fixed MgO thickness of 0.7 nm, it undergoes a crossover from a granular to a multilayered structure with increasing thickness of CoFeB and metallic conduction is reached at around 0.8 nm. In the granular state, a ferromagnetic to superparamagnetic phase transition was observed at 130 K. Different charge transport phenomena were identified at different temperatures. A sharp increase in the magnetoresistance at low temperature can be attributed to higher order tunneling processes. By proper annealing procedures, an enhanced magnetoresistance of around 6% at room temperature and 14% at low temperature as well as an increase in the resistivity have been achieved.
Why the iron magnetization in Gd2Fe14B and the spontaneous magnetization of Y2Fe14B depend on temperature differently
Authors: Kuz’min Michael D. , Givord Dominique , Skumryev Vassil
Published: June 2010

It is demonstrated that the temperature dependence of the iron sublattice magnetization in Gd2Fe14B is affected significantly by the Gd–Fe exchange interaction. This is at variance with the common perception that MFe(T) in iron-rich rare-earth intermetallics is determined predominantly by the Fe–Fe exchange. This phenomenon is discussed by considering the modification of the low-energy spin-wave spectrum of Gd2Fe14B, as compared to that of Y2Fe14B, under the influence of the Gd–Fe interaction. The result is of particular significance for evaluating the temperature dependence of the magnetocrystalline anisotropy of iron or cobalt compounds with anisotropic rare earths (e.g., Nd2Fe14B) and in turn, of the hard magnetic properties of such compounds.
Structure, magnetic, and microwave properties of thick Ba-hexaferrite films epitaxially grown on GaN/Al2O3 substrates
Authors: Chen Z. , Yang A. , Mahalingam K. , Averett K. L. , Gao J. , Brown G. J. , Vittoria C. , Harris V. G.
Published: June 2010

Thick barium hexaferrite [BaO⋅(Fe2O3)6] films, having the magnetoplumbite structure (i.e., Ba M), were epitaxially grown on c-axis oriented GaN/Al2O3 substrates by pulsed laser deposition followed by liquid phase epitaxy. X-ray diffraction showed (0,0,2n) crystallographic alignment with pole figure analyses confirming epitaxial growth. High resolution transmission electron microscopy images revealed magnetoplumbite unit cells stacked with limited interfacial mixing. Saturation magnetization, 4πMs, was measured for as-grown films to be 4.1±0.3 kG with a perpendicular magnetic anisotropy field of 16±0.3 kOe. Ferromagnetic resonance linewidth, the peak-to-peak power absorption derivative at 53 GHz, was 86 Oe. These properties will prove enabling for the integration of low loss Ba M ferrite microwave passive devices with active semiconductor circuit elements in systems-on-a-wafer architecture.
Electrical properties of p-type and n-type doped inverse silicon opals - towards optically amplified silicon solar cells
Authors: Suezaki T. , Chen J. I. L. , Hatayama T. , Fuyuki T. , Ozin G. A.
Published: June 2010

While the silicon photonic crystals have promised revolutionary developments in the field of optical telecommunications and optical computing, it has only recently been realized that their prowess to trap and slow photons could potentially and significantly improve the efficiency of silicon solar cells. In this work n-doped and p-doped inverse silicon opals are synthesized and processed to optimize their electrical charge transport properties, which are shown to be of semiconductor device quality. Moreover a prototype p-i-n junction solar cell based on the inverse silicon opal is reduced to practice and its optoelectronic behavior is evaluated.
Simultaneous plasma and electric field diagnostics of microdischarge from hydrogen Balmer line shape
Authors: Spasojević Dj. , Cvejić M. , Šišović N. M. , Konjević N.
Published: June 2010

Hydrogen Balmer beta line shape from a microhollow gas discharge in argon with traces of hydrogen is used for simultaneous diagnostics of plasma and cathode sheath parameters. Simple model of relevant processes responsible for line broadening is developed and results favorably compared with experiment at 500 mbar with the electron density 3.8×1020 m−3 and electric field strength of 127 kV/cm in the cathode sheath region.
Taylor’s (1935) dissipation surrogate reinterpreted
Authors: McComb W. David , Berera Arjun , Salewski Matthew , Yoffe Samuel
Published: June 2010

New results from direct numerical simulation of decaying isotropic turbulence show that Taylor’s expression for the viscous dissipation rate ε=CεU3/L is more appropriately interpreted as a surrogate for the inertial energy flux. As a consequence, the well known dependence of the Taylor prefactor Cε on Reynolds number Cε(RL)→Cε,∞ can be understood as corresponding to the onset of an inertial range.
Adiabatic hyperspherical study of weakly bound He2H−, He2H, and HeH2 systems
Authors: Suno Hiroya
Published: June 2010

The He2H−, He2H, and HeH2 triatomic systems are studied using the adiabatic hyperspherical representation. By adopting the best empirical interaction potentials, we search for weakly bound states of H4e2 H−, H4e2 H, and H4eH2. We consider not only zero total nuclear orbital angular momentum, J=0, states but also J>0 states. We find no bound state for the H4e2 H systems, while the H4e2 H− and H4eH2 systems are shown to possess three and one bound states, respectively, for JΠ=0+. Interestingly, one bound state has been found each for the JΠ=1− and 2+ symmetries of the H4e2 H− anion. We shall calculate the bound state energies and analyze the molecular structure of these species in detail.
Saturation of the Raman amplification by self-phase modulation in silicon nanowaveguides
Authors: Kroeger Felix , Ryasnyanskiy Aleksandr , Baron Alexandre , Dubreuil Nicolas , Delaye Philippe , Frey Robert , Roosen Gérald , Peyrade David
Published: June 2010

We experimentally show that the self-phase modulation of picosecond pump pulses, induced by both the optical Kerr effect and free-carrier refraction, has a detrimental effect on the maximum on-off Raman gain achievable in silicon on insulator nanowaveguides, causing it to saturate. A simple calculation of the Raman gain coefficient from the measured broadened output pump spectra perfectly matches the saturated behavior of the amplified Raman signal observed experimentally at different input pump powers.
Temperature dependence of optical anisotropy of birefringent porous silicon
Authors: Nishida Kohei , Fujii Minoru , Hayashi Shinji , Diener Joachim
Published: June 2010

Temperature dependence of the in-plane optical anisotropy of birefringent porous Si produced from a (110) Si wafer is studied. The anisotropy of refractive indices in the [001] and [11¯0] directions increased about 0.3% when the temperature rose from 30 to 100 °C. The effective medium approximation could reproduce the experimental result in the low temperature range, while discrepancy appeared at high temperatures. The discrepancy suggests that the structural anisotropy of porous Si starts to relax at relatively low temperatures.
Molecular basis for polyol-induced protein stability revealed by molecular dynamics simulations
Authors: Liu Fu-Feng , Ji Luo , Zhang Lin , Dong Xiao-Yan , Sun Yan
Published: June 2010

Molecular dynamics simulations of chymotrypsin inhibitor 2 in different polyols (glycerol, xylitol, sorbitol, trehalose, and sucrose) at 363 K were performed to probe the molecular basis of the stabilizing effect, and the data in water, ethanol, and glycol were compared. It is found that protein protection by polyols is positively correlated with both the molecular volume and the fractional polar surface area, and the former contributes more significantly to the protein’s stability. Polyol molecules have only a few direct hydrogen bonds with the protein, and the number of hydrogen bonds between a polyol and the protein is similar for different polyols. Thus, it is concluded that the direct interactions contribute little to the stabilizing effect. It is clarified that the preferential exclusion of the polyols is the origin of their protective effects, and it increases with increasing polyol size. Namely, there is preferential hydration on the protein surface (2 Å), and polyol molecules cluster around the protein at a distance of about 4 Å. The preferential exclusion of polyols leads to indirect interactions that prevent the protein from thermal unfolding. The water structure becomes more ordered with increasing the polyol size. So, the entropy of water in the first hydration shell decreases, and a larger extent of decrease is observed with increasing polyol size, leading to larger transfer free energy. The findings suggest that polyols protect the protein from thermal unfolding via indirect interactions. The work has thus elucidated the molecular mechanism of structural stability of the protein in polyol solutions.
TiO
2
nanotubes as a cold cathode for x-ray generation
Authors: Alivov Yahya , Klopfer Michael , Molloi Sabee
Published: June 2010

Here we report on an x-ray source based on titanium dioxide (TiO2) nanotubes grown by electrochemical oxidation. From the analysis of current-voltage characteristics of TiO2 electron emitter field emission nature of the current was confirmed. The threshold voltage and field enhancement factors were derived to be ∼1.8 V/μm and ∼8363, respectively. The current density was ∼4.0 mA/cm2 at ∼2.4 V/μm. The stability tests showed that the current stayed stable within 6% for more than 720 h. TiO2 nanotubes were used as a cold cathode in x-ray tube and it was demonstrated that TiO2 nanotubes could be a good candidate for such applications.