Flow equations of particle fluid mixtures

Summary A set of flow equations are derived for the velocity components of the solid and liquid phases of a particle fluid mixture. The equations have a limited validity to the case of uniaxial flow accompanied by radial expansion.The Terzaghi fluidization criterion is used to fix an internal parameter in the equations. Using a stability analysis it is demonstrated that the process of the onset of fluidization is accompanied by a smoothing out of internal heterogeneity in the system.The applications treated are the permeability of a densely packed material and the settlement of a geotechnical filter.     

Single and multi-specimenR-curve methods forJ IC determination of toughened nylons

For characterization of the fracture resistance of materials used in the upper shelf toughness regime,J-R curves are widely considered the most promising candidates. However, there still remain problems concerning both the generation and measurement ofJ-R curves as material characterizing parameters and their application in ductile fracture analyses for failure prediction in polymeric materials. This paper reports the results of investigations conducted on two rubbertoughened nylons at room temperature. Two different methods ofJ-R curve determination are covered, namely multi-specimen and single specimen test methods. The resultingJ-R curves have also been evaluated to obtain values of the initiation toughness,J _IC, following the extrapolation and interpolation schemes prescribed by ASTM E813-81 and ASTM E813-87 test procedures, respectively. The results show that the multiple specimen unloading method and the single specimen partial unloading compliance method can be used to generate comparable crack growth resistanceJ-R curves of the toughened nylons. The value ofJ _IC for the crystalline rubber-toughened nylon was approximately twice the value obtained for the amorphous rubber-toughened nylon. The former material also exhibited a greater resistance to ductile crack growth.     

Understanding the contributions of normal-fatigue and static loading to the dwell fatigue in a near-alpha titanium alloy

This article presents the results of a recent study of the response of an α/β-forged Ti-6Al-2Sn-4Zr-2Mo alloy during static, normal-fatigue, and dwell-fatigue loading. The plastic-strain accumulation under different loading conditions is reported. The failure modes and associated fractographic features under static, normal-fatigue, and dwell-fatigue loading conditions are also discussed. These results are used to obtain a better understanding of the relative contributions of the cyclic and creep processes to the overall damage under dwell-fatigue conditions.     

Production of silver‐doped analcime by isomorphous substitution technique

BACKGROUND: Metal‐exchanged zeolites have been reported to have significant limitations on cayalytic activity, such as counterbalancing the negative framework charges and limitation of active space. Alternative methods of incorporating silver ions into the framework of zeolites are therefore necessary. This paper reports on a technique for producing silver doped analcime by isomorphous substitution of silver ion into the framework of analcime. The amount of aluminium in the gel composition was reduced by a factor of 5%, 10% and 20% and an equivalent amount of silver was added to the gel and treated in a conventional manner for zeolite crystallisation. Some of the aluminium in the reaction gel was replaced with the silver. The silver‐doped analcime samples where characterised by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐rays (EDX), Fourier transform infrared (FTIR) spectroscopy and inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES) analysis. RESULTS: The amount of silver ions loaded for each reduction of aluminium as determined by EDX were found to be (w/w) 0.29%, 1.41% and 2.10%, respectively. XRD pattern SEM images of the silver‐doped analcime showed the presence of zeolite P in addition to analcime. CONCLUSION: Silver‐doped analcime was successfully produced with different silver loadings and may exhibit higher anti‐microbial activities than silver‐exchanged counterparts. Copyright © 2008 Society of Chemical Industry     

Maternal depression and early positive parenting predict future conduct problems in young children with attention-deficit/hyperactivity disorder.

Children with attention-deficit/hyperactivity disorder (ADHD) are at risk for adverse outcomes such as substance abuse and criminality, particularly if they develop conduct problems. Little is known about early predictors of the developmental course of conduct problems among children with ADHD, however. Parental psychopathology and parenting were assessed in 108 children who first met Diagnostic and Statistical Manual of Mental Disorders (4th ed.) criteria for ADHD at 4-7 years old. When demographic variables and baseline ADHD and conduct problems were controlled, maternal depression predicted conduct problems 2-8 years following the initial assessment, whereas positive parenting during the structured parent- child interaction task predicted fewer future conduct problems. These findings suggest that maternal depression is a risk factor, whereas early positive parenting is a protective factor, for the developmental course of conduct problems among children with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diamond nanoseeding on silicon: Stability under H2 MPCVD exposures and early stages of growth

Detonation nanodiamond dispersed on silicon surfaces underwent different H₂ MPCVD exposures. The induced changes at the surface have been characterized in situ by XPS and XEELS. Then, a short CH₄/H₂ growth step was applied. This sequential study revealed an excellent stability of detonation nanodiamond. The sp³ etching rate is insufficient to remove nanodiamond even under intense H₂ plasma. The H₂ exposure could be successfully used to remove C–C sp² carbon without altering sp³ seeds. Moreover, the formation of silicon carbide observed after the hydrogen treatment is thought to be helpful to enhance the adhesion of nanodiamond particles on the substrate.     

Chronic eosinophilic pneumonia and difficult to control asthma

We report a case of typical chronic eosinophilic pneumonia (CEP), in a female of 27 years-old suffering bronchial asthma light. Although the initial answer to the treatment with steroids was satisfactory, the patient develop difficult to control asthma (DCA). DCA is a clinical situation which requires careful investigation of several potential factors which can be solved. We suggest a protocol of treatment for patients affected with DCA.     

In-utero transplantation of parental CD34 haematopoietic progenitor cells in a patient with X-linked severe combined immunodeficiency (SCIDXI)

BACKGROUND: X-linked severe combined immunodeficiency (SCIDXI) is an inherited immune defect which leads to death in infancy from severe infections. The defect is caused by mutations of the IL-2RG gene that encodes for the common gamma chain shared by several cytokine receptors. The disease is characterised by lack of T and NK cells with normal numbers of B cells. SCIDXI can be cured by bone marrow transplantation (BMT) or prevented by abortion after prenatal diagnosis. METHODS: A male fetus was diagnosed as having SCIDXI by molecular, immunophenotypic, and functional analyses. The fetus was injected intraperitoneally under ultrasound guidance with CD34 haematopoietic progenitor cells purified from paternal bone marrow and T-cell depleted by E rosetting. Chimerism analysis was by HLA-DQ alpha typing and gamma-chain staining on cord blood. FINDINGS: A healthy 3.6 kg boy was delivered by caesarean section at 38 weeks of gestation with no clinical or laboratory signs of graft-versus-host disease. Engraftment of donor-derived CD2 cells was found at birth. At 3.5 months of age the infant is well and his T-cell counts and function are normal. INTERPRETATION: In-utero transplantation of haematopoietic progenitor cells allowed immune reconstitution of a fetus with SCIDXI and may be an alternative to elective abortion. Our report should encourage applications of this method to other inherited disorders curable by BMT.