bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of acute nervous system injury with advanced diffusion‐weighted MRI: a simulation and sensitivity analysis
Authors: Skinner Nathan P. , Kurpad Shekar N. , Schmit Brian D. , Budde Matthew D.
Published: September 2015

Diffusion‐weighted imaging (DWI) is a powerful tool to investigate the microscopic structure of the central nervous system (CNS). Diffusion tensor imaging (DTI), a common model of the DWI signal, has a demonstrated sensitivity to detect microscopic changes as a result of injury or disease. However, DTI and other similar models have inherent limitations that reduce their specificity for certain pathological features, particularly in tissues with complex fiber arrangements. Methods such as double pulsed field gradient (dPFG) and q‐vector magic angle spinning (qMAS) have been proposed to specifically probe the underlying microscopic anisotropy without interference from the macroscopic tissue organization. This is particularly important for the study of acute injury, where abrupt changes in the microscopic morphology of axons and dendrites manifest as focal enlargements known as beading. The purpose of this work was to assess the relative sensitivity of DWI measures to beading in the context of macroscopic fiber organization and edema. Computational simulations of DWI experiments in normal and beaded axons demonstrated that, although DWI models can be highly specific for the simulated pathologies of beading and volume fraction changes in coherent fiber pathways, their sensitivity to a single idealized pathology is considerably reduced in crossing and dispersed fibers. However, dPFG and qMAS have a high sensitivity for beading, even in complex fiber tracts. Moreover, in tissues with coherent arrangements, such as the spinal cord or nerve fibers in which tract orientation is known a priori, a specific dPFG sequence variant decreases the effects of edema and improves specificity for beading. Collectively, the simulation results demonstrate that advanced DWI methods, particularly those which sample diffusion along multiple directions within a single acquisition, have improved sensitivity to acute axonal injury over conventional DTI metrics and hold promise for more informative clinical diagnostic use in CNS injury evaluation. Copyright © 2015 John Wiley & Sons, Ltd.
The Human Circadian System Has a Dominating Role in Causing the Morning/Evening Difference in Diet‐Induced Thermogenesis
Authors: Morris Christopher J. , Garcia Joanna I. , Myers Samantha , Yang Jessica N. , Trienekens Noortje , Scheer Frank A.J.L.
Published: September 2015

Objective

Diet‐induced thermogenesis (DIT) is lower in the evening and at night than in the morning. This may help explain why meal timing affects body weight regulation and why shift work is a risk factor for obesity. The separate effects of the endogenous circadian system—independent of behavioral cycles—and of circadian misalignment on DIT are unknown.

Methods

Thirteen healthy adults undertook a randomized crossover study with two 8‐day laboratory visits: three baseline days followed either by repeated simulated night shifts including 12‐h inverted behavioral cycles (circadian misalignment) or by recurring simulated day shifts (circadian alignment). DIT was determined for up to 114 min (hereafter referred to as “early DIT”) following identical meals given at 8AM and 8PM in both protocols.

Results

During baseline days, early DIT was 44% lower in the evening than morning. This was primarily explained by a circadian influence rather than any behavioral cycle effect; early DIT was 50% lower in the biological evening than biological morning, independent of behavioral cycle influences. Circadian misalignment had no overall effect on early DIT.

Conclusions

The circadian system plays a dominating role in the morning/evening difference in early DIT and may contribute to the effects of meal timing on body weight regulation.
Frequent Self‐Weighing with Electronic Graphic Feedback to Prevent Age‐Related Weight Gain in Young Adults
Authors: Bertz Fredrik , Pacanowski Carly R. , Levitsky David A.
Published: September 2015

Objective

An intervention using Wi‐Fi scales and graphic e‐mail feedback, the caloric titration method (CTM), to reduce age‐related weight gain over 1 year among college students was evaluated.

Methods

First‐year college students (n = 167) were randomized to CTM or control (C) groups and provided Wi‐Fi scales. The CTM group was instructed to weigh daily, view a weight graph e‐mailed to them after weighing, and try to maintain their weight. The C group could weigh at any time but did not receive feedback. At 6 months and 1 year, the C group provided weights. For intention to treat analysis, an adjusted mixed model was used to analyze the effect of the intervention.

Results

Baseline body mass index was 22.9 ± 3.0 kg/m2. Ninety‐five percent of the CTM participants weighed ≥3 times/week, compared to 15% in the C group (P < 0.001). After 1 year, the C group had gained 1.1 ± 4.4 kg whereas the CTM group lost 0.5 ± 3.7 kg (F = 3.39, P = 0.035). The difference in weight change between the two groups at 1 year was significant (P = 0.004). Retention was 81%.

Conclusions

CTM intervention was effective in preventing age‐related weight gain in young adults over 1 year and thus offers promise to reduce overweight and obesity.
Liver Fibrosis Predicts Cognitive Function Following Bariatric Surgery: A Preliminary Investigation
Authors: Spitznagel Mary Beth , Gunstad John , Manderino Lisa , Heinberg Leslie
Published: September 2015

Objective

Obesity is a well‐established risk factor for poor neurological outcomes, and bariatric surgery has been shown to improve many aspects of cognitive function. Factors underlying improved cognition following surgery are not yet fully established. A recent study of bariatric surgery patients demonstrated lower preoperative alkaline phosphatase concentrations were linked to greater postoperative cognitive improvement, but this link has not been examined via liver biopsy. The current study examined postoperative cognitive function in individuals with and without fibrosis at the time of bariatric surgery. It expected that those with fibrosis would demonstrate poorer postoperative cognition.

Methods

Thirty‐six bariatric surgery patients underwent routine liver biopsy at the time of surgery and completed cognitive testing 1 month postoperatively.

Results

Bariatric surgery patients with fibrosis demonstrated poorer performance on a task of executive function (maze errors, P = 0.01) and verbal memory (recognition memory, P = 0.01).

Conclusions

Bariatric surgery patients with fibrosis demonstrated poorer cognition following surgery, providing further evidence for the connection between liver disease and cognitive function. Future work examining mechanisms underlying bariatric postoperative cognitive changes should include examination of broader metabolic functions, particularly liver function.
Regeneration versus scarring in vertebrate appendages and heart
Authors: Jaźwińska Anna , Sallin Pauline
Published: September 2015

Injuries to complex human organs, such as the limbs and the heart, result in pathological conditions, for which we often lack adequate treatments. While modern regenerative approaches are based on the transplantation of stem cell‐derived cells, natural regeneration in lower vertebrates, such as zebrafish and newts, relies predominantly on the intrinsic plasticity of mature tissues. This property involves local activation of the remaining material at the site of injury to promote cell division, cell migration and complete reproduction of the missing structure. It remains an unresolved question why adult mammals are not equally competent to reactivate morphogenetic programmes. Although organ regeneration depends strongly on the proliferative properties of cells in the injured tissue, it is apparent that various organismic factors, such as innervation, vascularization, hormones, metabolism and the immune system, can affect this process. Here, we focus on a correlation between the regenerative capacity and cellular specialization in the context of functional demands, as illustrated by appendages and heart in diverse vertebrates. Elucidation of the differences between homologous regenerative and non‐regenerative tissues from various animal models is essential for understanding the applicability of lessons learned from the study of regenerative biology to clinical strategies for the treatment of injured human organs. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
Mouse models of intestinal cancer
Authors: Jackstadt Rene , Sansom Owen J
Published: September 2015

Murine models of intestinal cancer are powerful tools to recapitulate human intestinal cancer, understand its biology and test therapies. With recent developments identifying the importance of the tumour microenvironment and the potential for immunotherapy, autochthonous genetically engineered mouse models (GEMMs) will remain an important part of preclinical studies for the foreseeable future. This review will provide an overview of the current mouse models of intestinal cancer, from the ApcMin/+ mouse, which has been used for over 25 years, to the latest ‘state‐of‐the‐art’ organoid models. We discuss here how these models have been used to define fundamental processes involved in tumour initiation and the attempts to generate metastatic models, which is the ultimate cause of cancer mortality. Together these models will provide key insights to understand this complex disease and hopefully will lead to the discovery of new therapeutic strategies. © 2015 The Authors. Pathological Society of Great Britain and Ireland.
Large animal models of atherosclerosis – new tools for persistent problems in cardiovascular medicine
Authors: Shim J , Al‐Mashhadi RH , Sørensen CB , Bentzon JF
Published: September 2015

Coronary heart disease and ischaemic stroke caused by atherosclerosis are leading causes of illness and death worldwide. Small animal models have provided insight into the fundamental mechanisms driving early atherosclerosis, but it is increasingly clear that new strategies and research tools are needed to translate these discoveries into improved prevention and treatment of symptomatic atherosclerosis in humans. Key challenges include better understanding of processes in late atherosclerosis, factors affecting atherosclerosis in the coronary bed, and the development of reliable imaging biomarker tools for risk stratification and monitoring of drug effects in humans. Efficient large animal models of atherosclerosis may help tackle these problems. Recent years have seen tremendous advances in gene‐editing tools for large animals. This has made it possible to create gene‐modified minipigs that develop atherosclerosis with many similarities to humans in terms of predilection for lesion sites and histopathology. Together with existing porcine models of atherosclerosis that are based on spontaneous mutations or severe diabetes, such models open new avenues for translational research in atherosclerosis. In this review, we discuss the merits of different animal models of atherosclerosis and give examples of important research problems where porcine models could prove pivotal for progress. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
In vitro and in vivo correlates of physiological and neoplastic human Fallopian tube stem cells
Authors: Yamamoto Yusuke , Ning Gang , Howitt Brooke E , Mehra Karishma , Wu Lingyan , Wang Xia , Hong Yue , Kern Florian , Wei Tay Seok , Zhang Ting , Nagarajan Niranjan , Basuli Debargha , Torti Suzy , Brewer Molly , Choolani Mahesh , McKeon Frank , Crum Christopher P , Xian Wa
Published: September 2015

High‐grade serous cancer (HGSC) progresses to advanced stages without symptoms and the 5‐year survival rate is a dismal 30%. Recent studies of ovaries and Fallopian tubes in patients with BRCA1 or BRCA2 mutations have documented a pre‐metastatic intramucosal neoplasm that is found almost exclusively in the Fallopian tube, termed ‘serous tubal intraepithelial carcinoma’ or STIC. Moreover, other proliferations, termed p53 signatures, secretory cell outgrowths (SCOUTs), and lower‐grade serous tubal intraepithelial neoplasms (STINs) fall short of STIC but share similar alterations in expression, in keeping with an underpinning of genomic disturbances involved in, or occurring in parallel with, serous carcinogenesis. To gain insight into the cellular origins of this unique tubal pathway to high‐grade serous cancer, we cloned and both immortalized and transformed Fallopian tube stem cells (FTSCs). We demonstrated that pedigrees of FTSCs were capable of multipotent differentiation and that the tumours derived from transformed FTSCs shared the histological and molecular features of HGSC. We also demonstrated that altered expression of some biomarkers seen in transformed FTSCs and HGSCs (stathmin, EZH2, CXCR4, CXCL12, and FOXM1) could be seen as well in immortalized cells and their in vivo counterparts SCOUTs and STINs. Thus, a whole‐genome transcriptome analysis comparing FTSCs, immortalized FTSCs, and transformed FTSCs showed a clear molecular progression sequence that is recapitulated by the spectrum of accumulated perturbations characterizing the range of proliferations seen in vivo. Biomarkers unique to STIC relative to normal tubal epithelium provide a basis for novel detection approaches to early HGSC, but must be viewed critically given their potential expression in lesser proliferations. Perturbations shared by both immortalized and transformed FTSCs may provide unique early targets for prevention strategies. Central to these efforts has been the ability to clone and perpetuate multipotent FTSCs. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Systematic transcriptome analysis reveals elevated expression of alcohol‐metabolizing genes in NAFLD livers
Authors: Zhu Ruixin , Baker Susan S , Moylan Cynthia A , Abdelmalek Manal F , Guy Cynthia D , Zamboni Fausto , Wu Dingfeng , Lin Weili , Liu Wensheng , Baker Robert D , Govindarajan Sugantha , Cao Zhiwei , Farci Patrizia , Diehl Anna Mae , Zhu Lixin
Published: September 2015

Obese animals and non‐alcoholic fatty liver disease (NAFLD) patients exhibit elevated blood alcohol, suggesting potential contributions of alcohol metabolism to the development of NAFLD. Liver gene expression in patients with biopsy‐proven mild (N = 40) and severe (N = 32) NAFLD were compared to that in healthy liver donors (N = 7) and alcoholic hepatitis (AH; N = 15) using microarrays. Principal components analyses (PCA) revealed similar gene expression patterns between mild and severe NAFLD which clustered with those of AH but were distinct from those of healthy livers. Differential gene expression between NAFLD and healthy livers was consistent with established NAFLD‐associated genes and NAFLD pathophysiology. Alcohol‐metabolizing enzymes including ADH, ALDH, CYP2E1, and CAT were up‐regulated in NAFLD livers. The expression level of alcohol‐metabolizing genes in severe NAFLD was similar to that in AH. The NAFLD gene expression profiles provide new directions for future investigations to identify disease markers and targets for prevention and treatment, as well as to foster our understanding of NAFLD pathogenesis and pathophysiology. Particularly, increased expression of alcohol‐metabolizing genes in NAFLD livers supports a role for endogenous alcohol metabolism in NAFLD pathology and provides further support for gut microbiome therapy in NAFLD management. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley © Sons, Ltd.
Simultaneous Detection of Flavonoids, Phenolic Acids and Alkaloids in Abri Herba and Abri Mollis Herba using Liquid Chromatography Tandem Mass Spectrometry
Authors: Yan Wenying , Han Qingjie , Guo Panpan , Wang Chunying , Zhang Zijian
Published: September 2015

Introduction

Abri Herba has remarkable properties, such as cleanup heat detoxification, dampness and activating blood circulation to dissipate blood stasis; as a result, it has been applied to treat acute or chronic hepatitis and mastitis. Abri mollis Herba is often used as Abri Herba. Hierarchical cluster analysis (HCA) was applied to compare the similarities and differences of the chemical compositions in the two types of medicinal materials.

Objective

To establish a high‐performance liquid chromatography and tandem mass spectrometry (HPLC–MS/MS) method for the simultaneous analysis of 15 flavonoids, two phenolic acids and three alkaloids in Abri Herba and Abri mollis Herba.

Methodology

The chromatographic separation was performed on a C18 column with a mobile phase of methanol (A), acetonitrile (B) and 0.5‰ acetic acid in water (C) using gradient elution. The detection of the target compounds was performed in multiple‐reaction monitoring (MRM) mode using a hybrid quadrupole linear ion trap mass spectrometer equipped with positive/negative ion‐switching electrospray ionisation (ESI) source.

Results

The developed method is reliable, sensitive and specific. In addition, the method has been successfully applied to differentiate 15 batches of Abri Herba and 27 batches of Abri mollis Herba stems. Furthermore, a comparison of the contents among stems, roots and leaves from the same strain in seven batches of Abri mollis Herba and four batches of Abri Herba has also been performed.

Conclusion

HPLC–MS/MS method is sensitive and selective and can be suitable for the reliable quality control of Abri mollis Herba and Abri Herba. Copyright © 2015 John Wiley & Sons, Ltd.
Perspective: Do macromolecules play a role in the mechanisms of nerve stimulation and nervous transmission?
Authors: Wnek Gary E.
Published: September 2015

Fibrillar macromolecular networks are ubiquitous in biological systems, from cellular cytoskeletons to tissues such as muscle and tendon. The presence of such networks in neuronal tissue is known, for example, in the cytoskeleton and extracellular matrix in and around neuronal and glial cells, but their function is believed to be principally mechanical/structural in nature. However, there has long been speculation regarding a broader role for neuronal fibrillar macromolecules, which are anionic polyelectrolytes, specifically regarding their participation in nervous stimulation and transmission. This Perspective reviews literature that spans more than a century, including very recent work, and attempts to build a case for considering a multifunctional role for such macromolecules that includes participation in not only nervous activity but also in diverse phenomena including electric communication within and between cells and mechanisms of anesthetic action. Perhaps the creation and utilization of “artificial axons” is within reach with design rules coming at least in part from fundamental considerations of macromolecular science. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 7–14
Reversible plasticity shape memory polymers: Key factors and applications
Authors: Zhang Xuhui , Tang Zhenghai , Guo Baochun
Published: September 2015

Reversible plasticity shape memory (RPSM) polymers have been emerging as new smart materials with distinctions compared with conventional SMPs, such as easier shaping programming, stronger recovery stress, and higher recovery strain. For purposeful control of the structure, and therefore the physical and mechanical properties, a full understanding of the deformation habits of such materials under different conditions is essential. This perspective provides the context as to how the deformation temperature and fixing conditions influence the fixity and recovery behavior of RPSM polymers and what are the optimized conditions for RPSM. We hope that this will afford useful information for fabricating RPSM polymers with better memory properties and promote the technical development of new design methods of such materials for advanced applications © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1295–1299
Antimicrobial loading into and release from poly(ethylene glycol)/poly(acrylic acid) semi‐interpenetrating hydrogels
Authors: Wu Yong , Liang Jing , Horkay Ferenc , Libera Matthew
Published: September 2015

Electrostatic interactions within a semi‐interpenetrating network (semi‐IPN) gel can control the postsynthesis loading, long‐term retention, and subsequent release of small‐molecule cationic antibiotics. Here, electrostatic charge is introduced into an otherwise neutral gel [poly(ethylene glycol) (PEG)] by physically entrapping high‐molecular‐weight poly(acrylic acid) (PAA). The network structure is characterized by small‐angle neutron scattering. PEG/PAA semi‐IPN gels absorb over 40 times more antibiotic than PAA‐free PEG gels. Subsequent soaking in physiological buffer (pH 7.4; 0.15 M NaCl) releases the loaded antibiotics for periods as long as 30 days. The loaded gels elute antibiotics with diffusivities of 4.46 × 10−8 cm2/s (amikacin) and 2.08 × 10−8 cm2/s (colistin), which are two orders of magnitude less than those in pure PEG gels where diffusion is controlled purely by gel tortuosity. The release and hindered diffusion can be understood based on the partial shielding of the charged groups within the loaded gel, and they have a significant effect on the antimicrobial properties of these gels. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 64–72
Deposition of Plasma‐Polymerized Polyacrylic Acid Coatings by a Non‐Equilibrium Atmospheric Pressure Nanopulsed Plasma Jet
Authors: Liguori Anna , Pollicino Antonino , Stancampiano Augusto , Tarterini Fabrizio , Focarete Maria Letizia , Colombo Vittorio , Gherardi Matteo
Published: September 2015

Successful plasma‐polymerization of acrylic acid (AA), aimed at depositing plasma‐polymerized polyacrylic acid (pPAA) coatings stable upon water contact with a high amount of carboxyl groups, using a non‐equilibrium atmospheric pressure nanopulsed plasma jet is reported. Special attention is devoted to the surface chemical characterization of the pPAA coatings deposited on pristine and plasma pretreated polymeric substrates. The investigation of the pPAA chemical structure is performed by means of attenuated total reflectance‐Fourier transform infrared and X‐ray photoelectron spectroscopies. Insights on the morphological characteristics of the coatings are also provided by optical microscopy.
Histological and Nuclear Medical Comparison of Inflammation After Hemostasis with Non‐Thermal Plasma and Thermal Coagulation
Authors: Ueda Masashi , Yamagami Daiki , Watanabe Keiko , Mori Asami , Kimura Hiroyuki , Sano Kohei , Saji Hideo , Ishikawa Kenji , Hori Masaru , Sakakita Hajime , Ikehara Yuzuru , Enomoto Shuichi
Published: September 2015

The objective of this study is to examine the invasiveness of hemostasis by non‐thermal plasma (NTP) compared with hemostasis by thermal coagulation (TC). The inflammation recovery process after hemostasis by TC and NTP was compared by using histological methods and nuclear medical molecular imaging. The necrotic areas in the NTP group disappeared after 5 days, whereas they remained 15 days after hemostasis in the TC group. The accumulation of 2‐deoxy‐2‐[18F]fluoro‐d‐glucopyranose (18F‐FDG), which reflects the existence of inflammatory cells, was higher in the TC group than in the NTP group on day 15. Thus, this study indicates that hemostasis by NTP is less inflammatory than TC. This report is the first to evaluate inflammation that occurred after hemostasis with medical devices noninvasively.
Trap‐assisted photon‐enhanced thermionic emission from polycrystalline diamond films
Authors: Elfimchev S. , Chandran M. , Akhvlediani R. , Hoffman A.
Published: September 2015

In this work, the photoelectron emission (PEE) in the temperature range of 298–873 K was investigated from undoped hydrogenated polycrystalline diamond (Poly‐Di) film. Poly‐Di film was deposited by hot filament chemical vapor deposition (HF CVD) method on silicon substrate. The sample was illuminated with monochromatic wavelengths of 360, 380, 400, and 440 nm and electron emission intensities were recorded as a function of temperature. The obtained results were compared with thermionic electron emission (TEE) from the same sample measured in the dark. In the temperature range 298–550 K, the photoemission intensity decreases with temperature for all wavelengths, most likely due to reduction of electron diffusion length with temperature. In the ∼550–873 K temperature range a very pronounced effect of photon‐enhanced thermionic electron emission (PETE) was detected. It was observed that the PETE process is a function of the incoming light wavelength and more prominent in the lower wavelength range. Data analysis shows that such photocurrent enhancement with temperature is well described by the Richardson–Dushman equation with low‐activation energy of 0.14 eV. Based on the obtained results the effect of PETE may be rationalized as a combined three‐step process: (i) photon excitation of electrons to the conduction band; (ii) electron–phonon scattering and electron capture by trapping centers; and (iii) thermal excitation from near conduction band trap levels into vacuum. Our results suggest that diamond can be considered as an active cathode with thermally stable negative electron affinity (NEA) and shallow trap levels as a platform for thermal electron emission concurrent with optical illumination.
Hydrogen induced dipole at the Pt/oxide interface in MOS devices
Authors: Kolomiiets Nadiia M. , Afanas'ev Valeri V. , Opsomer Karl , Houssa Michel , Stesmans Andre
Published: September 2015

Thanks to its good thermal stability, including resistance to oxidation, platinum (Pt) is widely used in prototyping a wide spectrum of electron devices ranging from metal‐oxide‐semiconductor (MOS) transistors to resistive switching memory cells. In this work, the energy barriers for electrons between the Fermi level of Pt and the conduction band of several oxide insulators (SiO2, Al2O3, HfO2, Hf0.8Al0.2Ox, Sr0.53Ti0.47O3) were determined by using internal photoemission of electrons. By combining this barrier value with the electron affinity of the particular oxide, the effective work function (EWF) of Pt was determined for different interfaces. As studied over the reference Pt/oxide/Si stacks de‐gassed in high vacuum at 400 °C, the EWF of Pt is found to differ significantly from the accepted vacuum WF value of 5.6 eV. The EWF is equal to 5.2 eV at the Pt/Al2O3 interface, 5.1 eV at Pt/HfO2, 5.3 eV at Pt/Hf0.8Al0.2Ox, 4.8 eV at Pt/SiO2, and 5.8 eV at the Pt/Sr0.53Ti0.47O3 interface indicating the presence of a polarization layer of which the contribution to the EWF depends on the oxide composition. Furthermore, annealing in H2 at 400 °C reduces the Pt EWF by ∼0.5 eV at all interfaces except for the Pt/Sr0.53Ti0.47O3 one. This observation indicates the formation of an additional H‐related dipole at the Pt/oxide interfaces and suggests that the vacuum WF of Pt cannot be used as the value relevant for the MOS properties.
Current and field driven domain wall motion under influence of the Dzyaloshinsky–Moriya interaction
Authors: Wieser Robert
Published: September 2015

A complete analytical description of the dynamics of current and field driven transverse domain walls under the influence of the Dzyaloshinsky–Moriya interaction using the q– model will be given. Five different scenarios will be observed where the Dzyaloshinsky–Moriya vector is either parallel or perpendicular to the easy axis anisotropy of the system and a direct reversal, respectively, precessional motion will be assumed.
Strain‐ and correlation‐induced half‐metallic ferromagnetism in orthorhombic BaFeO
Authors: Rahman Gul , Sarwar Saad
Published: September 2015

Using first‐principles calculations, the electronic and magnetic properties of orthorhombic BaFeO (BFO) are investigated with the local spin density approximation (LSDA). The calculations reveal that at the optimized lattice volume, BFO has a lower energy in the ferromagnetic state as compared with the antiferromagnetic state. At the equilibrium volume, BFO shows metallic behavior, however, under a large tensile strain (), BFO shows half‐metallic behavior consistent with the integer magnetic moment of fu mainly caused by the and electrons of Fe. Including a Hubbard‐like contribution U (LSDA) on Fe d states induced half‐metallic behavior without external strain, which indicates that U can be used to tune the electronic structure of BFO. The magnetic moments remained robust against compressive and tensile strain. At large compressive (tensile) strain, the half‐metallicity of BFO is mainly destroyed by the Fe‐d (O‐p) electrons, in agreement with the noninteger value of the magnetic moments of BFO.
Oxygen isotope studies of phosphite oxidation: Purification and analysis of reactants and products by high‐temperature conversion elemental analyzer/isotope ratio mass spectrometry
Authors: Chang Sae Jung , Blake Ruth E.
Published: September 2015

Rationale

Increased attention has been recently focused on the origin and reactions of reduced‐P oxyanions such as phosphite [PO3(III)] in terrestrial and biological systems. We present new methods for studying O‐isotopic reactions between PO3(III) and other oxygen sources during oxidation of PO3(III) to PO4(V).

Methods

Na2(HPO3)·5H2O, used as a PO3(III) source, contains structural water due to its hygroscopic nature; thus, we developed a method for determining the δ18O value of PO3(III) after the removal of structural water. Next, we tested two techniques for purifying PO4(V) from aqueous PO3(III)/PO4(V) mixtures: (1) precipitation of PO4(V) as ammonium phosphomolybdate (APM); and (2) precipitation of PO4(V) as magnesium ammonium phosphate (MAP). The O‐isotope compositions, 18O:16O (δ18O values), of Na2(HPO3) and Ag3PO4 were analyzed by TC/EA/IRMS.

Results

Structural water was removed from Na2(HPO3)·5H2O after drying at 100 °C under vacuum and the δ18O value of PO3(III) was obtained. The δ18O values of PO4(V), which was extracted from 18O‐labeled PO3(III)/PO4(V) mixtures by APM and MAP precipitations, were not altered by the precipitation process. This result confirms that PO3(III) is not converted into PO4(V) by oxidation or hydrolysis under either strong acidic/oxidizing (APM) or alkaline (MAP) conditions for up to a 24‐h period.

Conclusions

We conclude that both APM and MAP precipitation are reliable and effective methods for the separation and purification of PO4(V) from aqueous PO3(III)/PO4(V) mixtures. The methods described here will permit the study of the isotopic evolution of various pathways of geochemical as well as biological PO3(III) oxidation. Copyright © 2015 John Wiley & Sons, Ltd.
Site‐specific 13С/12С isotope abundance ratios in dicarboxylic oxyacids as characteristics of their origin
Authors: Zyakun Anatoly M. , Oganesyants Lev A. , Panasyuk Alexander L. , Kuz'mina Elena I. , Shilkin Aleksey A. , Baskunov Boris P. , Zakharchenko Vladimir N. , Peshenko Valentina P.
Published: September 2015

Rationale

Recommendations of relevant international organizations controlling the quality of grape wines and beverages specify that only tartaric acids of grape origin can be introduced to achieve the required parameters. The development of methods for determining the origin of tartaric acid in grape wine is of great technological significance.

Methods

Organic dicarboxylic oxyacids were extracted from wines as barium salts. Carbon dioxide, which included all the carbon atoms of the acids, was used to determine the carbon isotope ratios by Isotope Ratio Mass Spectrometry. The alkyl part of the oxyacids was burned at 560°C in the presence of air; BaCO3 containing the carboxyl carbon was left. This carbonate was used to measure the carbon isotope ratios in the carboxyl part of the acid. The carbon isotope ratios of the alkyl part of tartaric acid were found by isotope mass balance.

Results

The carbon isotope composition of carboxyl groups (δ13С values) in tartaric acid of grape (biogenic origin) had a higher 13С content than the carbon in the alkyl part of the molecule. Tartaric acid produced by chemical synthesis (abiogenic origin) was noted to have a different 13С/12С distribution: the carboxyl group of tartaric acid produced by chemical synthesis contained a smaller than or equal amount of 13С to the alkyl part.

Conclusions

This is the first determination of the site‐specific distribution of the 13С/12С isotopes in tartaric acids as evidence of their biogenic and abiogenic origins. The presented method for determining the origin of tartaric acid can be used for efficient control of the quality of grape wines and beverages. Copyright © 2015 John Wiley & Sons, Ltd.
Simultaneous analysis of 17O/16O, 18O/16O and 2H/1H of gypsum hydration water by cavity ring‐down laser spectroscopy
Authors: Gázquez Fernando , Mather Ian , Rolfe James , Evans Nicholas P. , Herwartz Daniel , Staubwasser Michael , Hodell David A.
Published: September 2015

Rationale

The recent development of cavity ring‐down laser spectroscopy (CRDS) instruments capable of measuring 17O‐excess in water has created new opportunities for studying the hydrologic cycle. Here we apply this new method to studying the triple oxygen (17O/16O, 18O/16O) and hydrogen (2H/1H) isotope ratios of gypsum hydration water (GHW), which can provide information about the conditions under which the mineral formed and subsequent post‐depositional interaction with other fluids.

Methods

We developed a semi‐automated procedure for extracting GHW by slowly heating the sample to 400°C in vacuo and cryogenically trapping the evolved water. The isotopic composition (δ17O, δ18O and δ2H values) of the GHW is subsequently measured by CRDS. The extraction apparatus allows the dehydration of five samples and one standard simultaneously, thereby increasing the long‐term precision and sample throughput compared with previous methods. The apparatus is also useful for distilling brines prior to isotopic analysis. A direct comparison is made between results of 17O‐excess in GHW obtained by CRDS and fluorination followed by isotope ratio mass spectrometry (IRMS) of O2.

Results

The long‐term analytical precision of our method of extraction and isotopic analysis of GHW by CRDS is ±0.07‰ for δ17O values, ±0.13‰ for δ18O values and ±0.49‰ for δ2H values (all ±1SD), and ±1.1‰ and ±8 per meg for the deuterium‐excess and 17O‐excess, respectively. Accurate measurement of the 17O‐excess values of GHW, of both synthetic and natural samples, requires the use of a micro‐combustion module (MCM). This accessory removes contaminants (VOCs, H2S, etc.) from the water vapour stream that interfere with the wavelengths used for spectroscopic measurement of water isotopologues. CRDS/MCM and IRMS methods yield similar isotopic results for the analysis of both synthetic and natural gypsum samples within analytical error of the two methods.

Conclusions

We demonstrate that precise and simultaneous isotopic measurements of δ17O, δ18O and δ2H values, and the derived deuterium‐excess and 17O‐excess, can be obtained from GHW and brines using a new extraction apparatus and subsequent measurement by CRDS. This method provides new opportunities for the application of water isotope tracers in hydrologic and paleoclimatologic research. © 2015 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd.
TABLE OF BESSEL FUNCTIONS Jn(1000)
Authors: Corrington Murlan S.
Published: September 2015

A table of Bessel functions for Jn(1000) is given covering the range n = 935(1)1035; 8D.
Tables of Bessel, Functions Jn(x) for Large Arguments
Authors: Corrington Murlan S. , Miehle William
Published: September 2015

Tables of Jn(ms) are given for n = 0(1)10, s = 1(1)20 and m = 1(1)10 to five decimal places. A second set of tables includes n = 0(1)10, s = 1(1)20 and m = π, 2π, ··· 5π also to five decimal places. These computed values have been arranged in tables with increasing s for use in the summation of the SchlOmil(lh series which occur in the theory of frequency modulation. The computed values have been checked against existing tables wherever possible.
Non‐linear Transformations of Divergent and Slowly Convergent Sequences
Authors: Shanks Daniel
Published: September 2015

This paper discusses a family of non‐linear sequence‐to‐sequence transformations designated as ek, ekm, ẽk, and ed. A brief history of the transforms is related and a simple motivation for the transforms is given. Examples are given of the application of these transformations to divergent and slowly convergent sequences. In particular the examples include numerical series, the power series of rational and meromorphic functions, and a wide variety of sequences drawn from continued fractions, integral equations, geometry, fluid mechanics, and number theory. Theorems are proven which show the effectiveness of the transformations both in accelerating the convergence of (some) slowly convergent sequences and in inducing convergence in (some) divergent sequences. The essential unity of these two motives is stressed. Theorems are proven which show that these transforms often duplicate the results of well‐known, but specialized techniques. These special algorithms include Newton's iterative process, Gauss's numerical integration, an identity of Euler, the Padé Table, and Thiele's reciprocal differences. Difficulties which sometimes arise in the use of these transforms such as irregularity, non‐uniform convergence to the wrong answer, and the ambiguity of multivalued functions are investigated. The concepts of antilimit and of the spectra of sequences are introduced and discussed. The contrast between discrete and continuous spectra and the consequent contrasting response of the corresponding sequences to the e1 transformation is indicated. The characteristic behaviour of a semiconvergent (asymptotic) sequence is elucidated by an analysis of its spectrum into convergent components of large amplitude and divergent components of small amplitude.
Rotationally Symmetric Stress and Strain in Shells of Revolution
Authors: Reissner E. , Wan F. Y. M.
Published: September 2015

In generalization of existing results of the linear theory of symmetrical bending and torsion of thin elastic shells of revolution and of the theory of pure bending and twisting of ring sector shells, this paper considers the differential equations of the theory of shells of revolution under the supposition of rotationally symmetric stress and strain, allowing for transverse shear deformation and for moments turning about the normals to the middle surface. In this way, making use of the simplified static‐geometric analogy which is associated with the introduction of the two mentioned effects, known results are rederived in a new way and some new results are obtained, in particular for the dislocation‐theory‐type problems of pure bending and twisting.
Random Wave Closures
Authors: Benney D. J. , Newell Alan C.
Published: September 2015

A detailed study is made of the way in which weak nonlinearities affect the statistical properties of a system of dispersive waves. Given that at some initial instant the spectral cumulants are sufficiently smooth it is shown that they will remain smooth to zeroth order, save in one dimension where a discrete spectrum may eventually be generated. Of prime interest is the fact that on considering the long time behavior of the system, one is led to a sequence of closures for the zeroth order spectral functions. Apparent difficulties associated with the irretraceability of the solution are discussed. The structure of the closure equations depends on the asymptotic behavior of a class of singular integrals.
The Spectra of Small Oscillations of Thin Disk Galactic Models
Authors: Hunter C.
Published: September 2015

This paper gives a survey of the spectral properties of the frequencies of small oscillations, both in and perpendicular to their plane, of cold thin disk galactic models. The spectra can have discrete and continuous parts, with two quite distinct types of continua arising. One type occurs with both kinds of oscillation when the density at the outer edge of the disk becomes sufficiently rarified. It is associated with rapid fluctuations in the outer region. The other type of continuum occurs for non‐axisymmetric oscillations in the plane of non‐uniformly rotating disks. Some significant discrete oscillations of fundamental type are found that exist in addition to the various continua.
On the Equations of Linear Shallow Shell Theory
Authors: Reissner E. , Wan F. Y. M.
Published: September 2015

The paper presents a formulation of the two‐dimensional theory of shallow shells, including the effects of transverse shear deformation and of moments turning about the normal to the middle surface. The present formulation includes, as it must, Marguerre's theory. At the same time it is consistent with recent formulations of general linear shell theory, in particular in regard to the preservation of the static‐geometric duality. Various reductions of the equation of the theory are considered. Of particular significance and effectiveness among these are reductions for the special cases of (1) shells without moments about the middle surface normal, (where an earlier result of Naghdi is extended) (2) the shell without transverse shear deformability, (the static‐geometrical dual of case (1)). As an application of the general equations an explicit solution is obtained for the problem of stretching, twisting and bending of pretwisted rectangular plates.
Stress Functions for Nonlinear Shallow Shell Theory
Authors: Wan F. Y. M.
Published: September 2015

This note obtains the stress function solution of the homogeneous equilibrium equations of the nonlinear shallow shell theory as formulated in [1].
Scattering of Inertial Waves in a Rotating Fluid
Authors: Barcilon Victor , Bleistein Norman
Published: September 2015

The scattering of plane inertial waves by both a flat strip and a circular cylinder whose generators are perpendicular to the rotation vector is examined. The properties of the reflected and diffracted fields, viz. spatial decay, propagation, structure, etc....are contrasted with those of the classical scattering fields in the limit where the wave length is small compared to the size of the scatterer.
An Asymptotic Dynamic Theory for Cylindrical Shells
Authors: Johnson M. W. , Widera O. E.
Published: September 2015

By expanding the displacement and stress components together with the axial length scale in terms of a small thin shell parameter, three asymptotic shell theories are obtained which incorporate thickness effects in a systematic way. The expansions are made in the equations of linear three‐dimensional elasticity. These theories are used to examine the problem of longitudinal wave propagation in a shell of infinite length.
Theory of Complex Angular Momentum: Past and Future
Authors: Cheng Hung
Published: September 2015

Three fundamental subjects on Regge poles are discussed in this paper. They are: (i) the relationship between the Mandelstam representation and the theory of complex angular momentum; (ii) the validity of the Regge asymptotic form for a general, complex s, (which includes the physical region of the t channel as a special case); (iii) a major obstacle in the future of Regge poles as a complete scheme of dynamical calculations.
Scattering of Inertial Waves by Smooth Convex Cylinders
Authors: Barcilon Victor , Bleistein Norman
Published: September 2015

A general method of solution of the hyperbolic partial differential equation governing the scattering of inertial waves in a rotating fluid is presented for the case of cylindrical scatterers with smooth convex cross‐sections. The specific case of a parabolic cylinder is discussed in some detail.
Wave Instabilities
Authors: Benney D. J. , Roskes G. J.
Published: September 2015

A uniform train of periodic waves may be unstable to large scale variations so that some incoherence can develop. The analysis is presented for the case of gravity waves, and for a class of interaction problems typical of many physical systems.
Aerodynamic Sound Emission as a Singular Perturbation Problem
Authors: Crow S. C.
Published: September 2015

Sound emission from an eddy region involves three length scales: the eddy size I, wavelength λ of the sound, and a dimension L ofthe region. They are related by the Mach number M = l/λ, small for nearly incompressible eddies, and a parameter Λ = L/λ which plays no apparent role in current theories of aerodynamic sound. The theories of Lighthill and Ribner are examined in the case M ≪ 1, Λ ˜ 1. Ribner's result is found to contain an unacceptable improper integral. The utility of Lighthill's solution is found to depend on properties of the quadrupole moment Tij that can be established only by studying the flow in more detail than Lighthill's theory allows. The general problem is posed in the form: given the body force f and vorticity ω find the density ρ and potential φ of the velocity u = ∇ × ψ{ω} + ∇φ The problem is solved for M ≪ 1, Λ ˜ 1 by matching a compressible eddy core scaled on I to a surrounding acoustic field scaled on λ. Lighthill's solution for ρ is shown to be adequate in both regions if Tij is approximated by ρ0υiυj, with v = ∇ × ψ. The situation M ≪ 1, Λ ≫ 1 is studied, and the conclusion is reached that sound emission from large bodies of turbulence is an open problem, Lighthill's theory notwithstanding.
The Rotation of a Gravitating Sphere in a Monatomic Gas, I
Authors: Foster M. R.
Published: September 2015

The flow resulting from the steady rotation of a gravitating sphere in a monatomic gas is studied in two special cases. If the rotation is slow, then the motion consists of a swirling flow whose streamlines are concentric circles around the rotation axis, and a slower meridional flow whose structure depends on the strength of the gravitational field. This meridional flow is investigated in detail for small and large field strength. In the latter case, the scale height is small compared to the sphere radius, and most of the fluid is in a thin recirculating layer on the surface. However, the mathematics imposes a severe restriction on the rotation speed if the field is large, which leads to a more general investigation of the flow for very large field strength, i.e. for a thin “atmosphere”. Compressibility effects can be quite sizeable in this final solution. Though a thin recirculating surface layer still exists in only slightly modified form, the fluid outside this layer is much less tenuous than for the case when the rotation is slow. The flow in the region outside the boundary layer involves solution of two quasilinear elliptic equations.
The Velocity of Viscous Vortex Rings
Authors: Saffman P. G.
Published: September 2015

The motion of vortex rings of small cross section is considered. A formula is derived for the velocity of a ring in an ideal fluid with an arbitrary distribution of vorticity in the core. The effects of viscosity are then examined. A definition of the velocity of an unsteady diffusing ring is given and it is shown that the method used to calculate the ring speed in an ideal fluid can be extended to give the velocity of a vortex ring subject to viscous diffusion.
A Note on Edge Waves in a Stratified Fluid
Authors: Greenspan H. P.
Published: September 2015

Explicit solutions are given for edge waves on a sloping beach in an exponentially stratified fluid. The lowest mode, Stoke's edge wave, is found to be completely insensitive to the density field. The higher modes show that previous restrictions on slope angle etc., no longer apply.