Lattice dynamics and Born instability in yttrium aluminum garnet, Y3Al5O12

We report lattice dynamics calculations of various microscopic and macroscopic vibrational and thermodynamic properties of yttrium aluminum garnet (YAG), Y3Al5O12, as a function of pressure up to 100 GPa and temperature up to 1500 K. YAG is an important solid-state laser material with several technological applications. Garnet has a complex structure with several interconnected dodecahedra, octahedra and tetrahedra. Unlike other aluminosilicate garnets, there are no distinct features to distinguish between intramolecular and intermolecular vibrations of the crystal. At ambient pressure, low energy phonons involving mainly the vibrations of yttrium atoms play a primary role in the manifestations of elastic and thermodynamic behavior. The aluminum atoms in tetrahedral and octahedral coordination are found to be dynamically distinct. Garnet's stability can be discerned from the response of its phonon frequencies to increasing pressure. The dynamics of both octahedral and tetrahedral aluminum atoms undergo radical changes under compression which have an important bearing on their high pressure and temperature properties. At 100 GPa, YAG develops a large phonon bandgap (90-110 meV) and its microscopic and macroscopic physical properties are found to be profoundly different from that at the ambient pressure phase. There are significant changes in the high pressure thermal expansion and specific heat. The mode Grüneisen parameters show significant changes in the low energy range with pressure. Our studies show that the YAG structure becomes mechanically unstable around P = 108 GPa due to the violation of the Born stability criteria. Although this does not rule out thermodynamic crossover to a lower free energy phase at lower pressure, this places an upper bound of P = 110 GPa for the mechanical stability of YAG.

Reuse and recycling of secondary effluents in refineries employing advanced multi-barrier systems

In this paper the reclamation and reuse of municipal secondary effluents, as well as the reclamation and recycling of refinery secondary effluents, are technically and economically evaluated. It is shown that both practices are feasible and sustainable, and that the reclamation costs depend largely on specific circumstances such as legal requirements, price policy, reuse application, raw water composition, etc. The reclaimed water is reused, or respectively recycled, as boiler make-up. Therefore both reclamation plants employ advanced multi-barrier systems including ultra-filtration and reverse osmosis. The employed processes have shown excellent performance with regard to the removal of critical parameters such as silica. For example, this parameter was reduced from 13 mg/l in the raw water to 7 μg/l in the boiler make-up.

Introduction and methodology - Guidelines on Parenteral Nutrition, Chapter 1

Guidelines for Parenteral Nutrition were prepared by the German Society for Nutritional Medicine (http://www.dgem.de/), in collaboration with other medical associations to provide guidance for quality assurance for parenteral nutrition (PN) practice, and to promoting health and quality of life of patients concerned. A coordination team proposed topics, working group leaders who along with working group members performed systematic literatur searches and drafted recommendations in a nominal group process. Recommendations were discussed and agreed upon in a structured consensus conference process, followed by a Delphi consensus. The current English version of the guidelines was written and updated during the period between the last quarter of 2007 and the first quarter of 2009. The recommendations of the guidelines should be reviewed, and if necessary updated five years after publication.

Sperm characteristics and ultrastructure of testes of rats after long-term treatment with the methanol subfraction of Carica papaya seeds

The contraceptive efficacy of Carica papaya seeds after short-term evaluation has been well established. We have examined the safety and mechanism of contraception in rats after long-term treatment with the methanol subfraction (MSF) of C. papaya seeds. The test substance was administered orally to the male albino rats (n = 40) at 50 mg per kg body weight each day for 360 days. Control animals (n = 40) received olive oil as a vehicle. Recovery was assessed up to 120 days after treatment withdrawal. Sperm parameters, serum testosterone levels, fertility, histology and ultrastructure of the testis, haematology and serum clinical chemistry were evaluated to establish the safety and efficacy of the test substance. Safety of long-term treatment was evidenced by unaltered health status, organ weight, haematology and clinical chemistry, and by an increase in body weight. The mechanism of contraception was shown by reduction in nuclear and cytoplasmic volume, normal nuclear characteristics and vacuolization in the cytoplasmic organelles of the Sertoli cells, as well as nuclear degeneration in spermatocytes and spermatids indicating disturbed spermatogenesis. Leydig cells were normal. Initial effects were observed in Sertoli cells at 60 days of treatment. Spermatocytes and spermatids were affected after 120-240 days of treatment. A significant decline in sperm count and viability, total inhibition of sperm motility, increased numbers of sperm abnormalities, normal serum testosterone levels and 100% sterility were evident after 60 days of treatment. All the altered parameters, including percent fertility, were restored to control level 120 days after treatment withdrawal. It is concluded that the MSF is safe for long-term treatment and the mechanism of contraception is shown by its effect on spermatid differentiation in the testis, possibly mediated by the Sertoli cell factors.

Parametric structural modeling of insect wings

Insects produce thrust and lift forces via coupled fluid-structure interactions that bend and twist their compliant wings during flapping cycles. Insight into this fluid-structure interaction is achieved with numerical modeling techniques such as coupled finite element analysis and computational fluid dynamics, but these methods require accurate and validated structural models of insect wings. Structural models of insect wings depend principally on the shape, dimensions and material properties of the veins and membrane cells. This paper describes a method for parametric modeling of wing geometry using digital images and demonstrates the use of the geometric models in constructing three-dimensional finite element (FE) models and simple reduced-order models. The FE models are more complete and accurate than previously reported models since they accurately represent the topology of the vein network, as well as the shape and dimensions of the veins and membrane cells. The methods are demonstrated by developing a parametric structural model of a cicada forewing.

Screening of codeine, dextromethorphan & dextropropoxyphene for their genotoxicity in Swiss albino mice

BACKGROUND & OBJECTIVE

It is mandatory for all new drugs to be tested for their potential genotoxicity in addition to general toxicity testing. Some old drugs have not been tested adequately for their genotoxic effects as these were in use before the regulations were enforced. The present study therefore aims to explore the genotoxic potential of some commonly used opioids like codeine, dextromethorphan and dextropropoxyphene in swiss albino mice.

METHODS

Therapeutic equivalent doses of codeine, dextromethorphan and dextropropoxyphene were given orally. Single dose for acute study and multiple doses (repeated every 24 h for 7 times) in additional groups of mice (n=5 in each) for subacute study. Cyclophosphamide served as positive control while normal saline as negative control. About 0.5 ml of blood was collected by retroorbital sinus for comet assay and later the mice were sacrificed to aspirate the femoral bone marrow for micronucleus test. Percentage of micronucleated polychromatic erythrocytes (MnPCE) and comet tail length were calculated in micronucleus assay and comet assay respectively, which served as markers of genotoxicity.

RESULTS

Significant (P<0.001) increase in comet tail length and % MnPCE was observed in both acute and subacute studies of cyclophosphamide group, whereas codeine, dextromethorphan and dextropropoxyphene treated groups did not show any significant changes.

INTERPRETATION & CONCLUSION

The results indicated that codeine, dextromethorphan and dextropropoxyphene were devoid of genotoxicity in mice.

Measurement of anomalous phonon dispersion of CaFe2As2 single crystals using inelastic neutron scattering

We measured phonon dispersions of CaFe2As2 using inelastic neutron scattering and compared our results to predictions of density functional theory in the local density approximation. The calculation gives correct frequencies of most phonons if the experimental crystal structure is used, except observed linewidths/frequencies of certain modes were larger/softer than predicted. Strong temperature dependence of some phonons near the structural phase transition near 172 K may indicate strong electron-phonon coupling and/or anharmonicity, which may be important for superconductivity.

White paper on academic emergency medicine in India: INDO-US Joint Working Group (JWG)

Emergency Medicine (EM) is a new discipline for India. As Medical Council of India (MCI) makes progress in recognizing the need to develop EM residency training programs in India it is important that there exist an established training model for future faculty, residents and medical students. This INDO-US white paper makes a serious attempt to recognize the opportunities and challenges in developing academic emergency medicine in India. The contents of this white paper address the overall scenario and are not targeted towards a person, physician, body, hospital or any other associated entity. This paper emphasizes the importance of MCI recognized training in Emergency Medicine for physicians in India.

WITHDRAWN: National Guidelines. Guidelines on Parenteral Nutrition from the German Society for Nutritional Medicine (DGEM) - Part 1

This article has been withdrawn at the request of the authors and Editor. The publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

[Malassezia furfur colonising the respiratory tract of mechanically ventilated neonates]

BACKGROUND

Ventilated neonates are prone to acquire ventilator-associated pneumonia (VAP). Consequently early diagnosis of pneumonia is required. Beside bacteria, fungi are suspected as a cause of VAP. However, fungal colonisation and infection of the lung have not been studied systematically. The purpose of this study was to evaluate pulmonary fungal colonisation in ventilated neonates and premature infants.

MATERIALS AND METHODS

187 tracheal aspirates (TA) from 29 ventilated neonates (23-35 weeks gestational age) were investigated. TAs were evaluated microscopically and by culture. Data were matched with clinical signs of VAP or sepsis.

RESULTS

Candida species were not detected in TA or culture. In contrast, Malassezia furfur (Mf), a lipophilic fungus, was detected from the 10th, 21st and 31st postnatal days onwards in TAs of 3 out of 17 extremely prematures (gestational age at birth < 25 weeks). The presence of Mf was associated with clinical deterioration either immediately or a few days after the first positive Mf smear. Topic steroids were more frequently applied to Mf-positive ELBW infants (p = 0.03). In vitro, natural surfactant was demonstrated to be a sufficient substrate for Mf in culture.

CONCLUSION AND DISCUSSION

This is the first report on Mf lung colonisation of ELBWI during mechanical ventilation. Because Mf is generally not detected in standard cultures it appears to be an overlooked, potentially pathogenic fungus in prematures. Mf must be considered in the differential diagnosis of VAP in ELBWI exposed to topical steroids, especially when natural surfactant was administered.

A VERSATILE SHARP INTERFACE IMMERSED BOUNDARY METHOD FOR INCOMPRESSIBLE FLOWS WITH COMPLEX BOUNDARIES

A sharp interface immersed boundary method for simulating incompressible viscous flow past three-dimensional immersed bodies is described. The method employs a multi-dimensional ghost-cell methodology to satisfy the boundary conditions on the immersed boundary and the method is designed to handle highly complex three-dimensional, stationary, moving and/or deforming bodies. The complex immersed surfaces are represented by grids consisting of unstructured triangular elements; while the flow is computed on non-uniform Cartesian grids. The paper describes the salient features of the methodology with special emphasis on the immersed boundary treatment for stationary and moving boundaries. Simulations of a number of canonical two- and three-dimensional flows are used to verify the accuracy and fidelity of the solver over a range of Reynolds numbers. Flow past suddenly accelerated bodies are used to validate the solver for moving boundary problems. Finally two cases inspired from biology with highly complex three-dimensional bodies are simulated in order to demonstrate the versatility of the method.

Fibrolipomatous hamartoma of median nerve

Fibrolipomaous hamartoma is a benign neoplasm of nerves, resulting from anomalous growth of fibroadipose tissue of the nerve sheath. The median nerve is the most commonly involved nerve. Magnetic resonance imaging (MRI) features are pathognomonic, showing a coaxial cable-like appearance on axial images and spaghetti-like appearance on coronal images. Preferred management of the lesion is conservative.

Review article: acidity and volume of the refluxate in the genesis of gastro-oesophageal reflux disease symptoms

BACKGROUND

A number of mechanisms, other than acid reflux, may be responsible for the symptoms of gastro-oesophageal reflux disease.

AIM

To assess the importance of non-acid reflux mechanisms.

METHODS

This review is based on presentations and discussion at a workshop, where specialists in the field analysed data relating to these mechanisms.

RESULTS

Weakly acidic reflux, pH (4-7), detected with impedance-pHmetry is associated with regurgitation and atypical gastro-oesophageal reflux disease symptoms. It is not clear whether pepsin and trypsin can elicit symptoms, but bile can elicit heartburn. The magnitude of reflux-induced oesophageal distension can be determined by high frequency ultrasonography and is not reduced by proton pump inhibition, suggesting that persisting symptoms 'on' a proton pump inhibitor may still be due to oesophageal distension by non-acidic reflux. Exaggerated longitudinal muscle contraction can induce non-acid-related heartburn. Preliminary studies showed a positive effect of baclofen, surgery or endoscopic procedures to reduce weakly acidic reflux.

CONCLUSION

Mechanisms other than acid reflux are involved in some of the symptoms of gastro-oesophageal reflux disease. Controlled outcome studies are needed to clarify their roles and the indications for antireflux procedures in patients with persistent symptoms whilst 'on' a proton pump inhibitor.

Primary splenic flexure volvulus

Primary splenic flexure volvulus is a rare entity. We report an acute presentation of primary splenic flexure volvulus with gangrene in a 24-year-old man. Radiograph showed a massively-dilated large bowel loop with a coffee-bean sign. At emergency laparotomy, a distended and gangrenous splenic flexure was found, with absence of all three ligamentous attachments of the splenic flexure.