Precise extraction of the induced polarization in the 4He(e,e'p)3H reaction.

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3 (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Polarization transfer in the 4He(e,e'p)3H reaction at Q2=0.8 and 1.3 (GeV/c)2.

Proton recoil polarization was measured in the quasielastic 4He(e,e'p)3H reaction at Q{2}=0.8 and 1.3 (GeV/c){2} with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the 1H(e,e'p) reaction, contradicting a relativistic distorted-wave approximation and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.

Detrimental consequences of the paracetamol tablet elastic relaxation during ejection.

BACKGROUND: It is generally accepted that the tablet elastic relaxation during compaction plays a vital role in undermining the final tablet mechanical integrity. One of the least investigated stages of the compaction process is the ejection stage. METHOD: This work has successfully monitored the paracetamol tablet dimensional changes during ejection using noncontact dimensional measuring devices. The extent of the tablet damage was physically viewed by examining the presence of cracks on the tablet side surfaces upon complete ejection from the die cavity. RESULTS: Damaged tablets were obtained when the paracetamol tablets exhibited comparatively high elastic relaxation during the ejection stage of the compaction process. CONCLUSION: Hence, this work presents evidences of the detrimental consequences of the paracetamol tablet elastic relaxation during ejection on its final mechanical integrity..

Interfacial elastic relaxation during the ejection of bi-layered tablets.

The predilection of a bi-layered tablet to fail in the interface region after its initial formation in the compaction process reduces its practicality as a choice for controlled release solid drug delivery system. Hence, a fundamental appreciation of the governing mechanism that causes the weakening of the interfacial bonds within the bi-layered tablet is crucial in order to improve the overall bi-layered tablet mechanical integrity. This work has shown that the occurrence of the elastic relaxation in the interface region during the ejection stage of the compaction process decreases with the increase in the bi-layered tablet interface strength. This is believed to be due to the increase in the plastic bonding in the interface region. The tablet diametrical elastic relaxation affects the tablet height elastic relaxation, where the impediment of the tablet height expansion is observed when the interface region experiences a diametrical expansion.

Axial tensile fracture of microcrystalline cellulose compacts.

An adapted tensile stress methodology for the fracture of microcrystalline cellulose (MCC) tablets has been investigated and implemented. The application of the generally applied linear elastic fracture mechanic (LEFM) parameters used to describe the fracture behaviour of these porous systems has been discussed. The application of an effective crack length concept, comprising of the notch depth and a process zone length designated delta c, has enabled the localised non-linear response of the MCC tablets to be characterised in a quantified manner. The requirement of the composite value delta c is postulated to be a direct result of the internal properties of the tablet formed during the compaction process due to its strong dependence on porosity. The high compact relative density creates a greater possibility for both local small-scale plastic yielding at the crack tip, commonly found in polymer materials and microcracking ahead of the crack tip, typically observed in the fracture of ceramics. The extrapolated value of KIC0 of 0.72 MPa m0.5 found in this work lies within the range found in literature for this material indicating that the adopted procedure is acceptable for the determination of the resistance to fracture of MCC compacts.

A study on the coherence of compacted binary composites of microcrystalline cellulose and paracetamol.

This paper describes and interprets the coherence and the tensile strength of bi-component compacted tablets, composing a mixture of a poorly compactable drug, paracetamol and a very cohesive and ductile carrier, microcrystalline cellulose (MCC), Avicel PH 102, using the concepts of the stored elastic strain in conjunction with the particle size and the relative volume fraction of the powders. Cylindrical compacts of the bi-component tablets, at various compositions formed at a common ultimate stress of 99 MPa, were subsequently fractured using the indirect tensile test method (Brazilian test method) to obtain a measure of their tensile strength. Various inter-relations between the compaction and tensile rupture characteristics are described. A simple model, which may predict the required volume fraction of MCC to produce a cohesively viable tablet is suggested, and applied to the current system. The results show to some extent the consistency of the suggested model with the experimental results.

Effects of particle size on near-wall depletion in mono-dispersed colloidal suspensions.

In this work we investigate the change in particle concentration near a solid boundary for colloidal dispersions in pressure driven flow, commonly referred to as wall depletion. In particular we determine the effect of Peclet number on the strength and spatial extent of the depleted layer. The change in concentration near the solid boundary is measured with attenuated total reflection infrared (ATR-IR) spectroscopy described previously (P.J.A. Hartman Kok et al., J. Rheol. 46 (2002) 481). The method is capable of measuring the concentration of particles at distances ranging from 0.2 to 1.0 mum from the boundary. The suspensions investigated consisted of mono-dispersed polystyrene particles in water. Particles of four different sizes were used, with radius, a, of 30, 54, 105, and 197 nm. (The ratio H/a was in the range 2500-17,000 with H being the height of the flow cell.) This enabled us to measure the wall depletion effect over a wide range of Peclet numbers, ranging from 0.01 to 45. We found that wall depletion was not significant for Peclet numbers smaller than unity. Estimates of the wall slip layer thickness obtained from rheological experiments were consistent with the results obtained by ATR-IR spectroscopy.

An algal removal using a combination of flocculation and flotation processes.

The paper describes certain facets of the removal of the algae (Scenedesmus quadricauda) from water, using a froth flotation separation method, in conjunction with two types of surfactants, (cetyltrimethylammonium bromide) CTAB and (sodium dodecylsulfate) SDS. A 90% algal removal efficiency was achieved when 100 mg l(-1) of CTAB was used whereas for the SDS solutions, the same concentration gave, by comparison, a very poor algal removal efficiency. An addition of 1 mg l(-1) of a commercial cationic polyelectrolyte, which was the optimal concentration as was evident from the zeta potential and the particle size distribution measurements, prior to the SDS addition resulted in a formation of algal flocs and consequently a substantial improvement in the extent of the algal removal. A 50 mg l(-1) solution of SDS was found to be the optimal concentration to completely remove these algal flocs from water. The amount of water removed along with the algal flocs, produced using 1 mg l(-1) of the commercial polyelectrolyte and subsequently removed using SDS, was comparatively lower than that removed with the algal cells when CTAB was used as the 'collector'. It was generally found, in this study, that an addition of the polyelectrolyte improved the removal efficiencies and the rate of separation and also decreased the amount of the associated water removed along with the algal sludge.

Couette flow of two immiscible liquids between two concentric cylinders: the formation of toroidal drops and liquid sheaths.

We describe the direct observation of deforming water drops in oil undergoing shear flow in a horizontal annular Couette cell. The drops assume a wide variety of highly reproducible structures depending on drop size, rotation speed, and flow history. These structures include toroidal rings of water around the rotating shaft and water sheaths, which, depending on experimental conditions, can either expand to press against the inner walls of the outer stationary cylinder or contract to hug the outside of the rotating shaft.

Genetic abortion: considerations for patient care.

Women who receive abnormal prenatal diagnosis results potentially face two emotionally difficult decisions. In this article, the first decision--whether or not to terminate the pregnancy--is presented with a discussion of the factors that may influence a women's choice. Women who choose to terminate the pregnancy face a second decision when more than one type of abortion procedure is available. Two second trimester abortion procedures--dilation and evacuation and labor induction--are compared and contrasted to delineate potential advantages and disadvantages of each. The decision-making process is examined, emphasizing the individual ways in which women may weigh this information to make a fully informed decision. In addition, a number of recommendations are offered to health care providers in the role of discussing options and supporting women in their choices.

Prevalence and habitat specificity of steinernematid and heterorhabditid nematodes isolated during soil surveys of the UK and the Netherlands.

Entomopathogenic nematodes were isolated from soil samples collected during three separate surveys, two in the United Kingdom and one in the Netherlands. The nematodes were identified by their restriction fragment length polymorphisms on hybridization of Southern blots with a ribosomal DNA repeat unit clone. A total of eight steinernematid species/RFLP types and two heterorhabditids were isolated. The distributions of the majority of these species/RFLP types were significantly different between the three surveys and some of the species displayed a close association with certain habitat types.

Establishing pediatric cancer nursing research priorities: a Delphi study.

The purpose of this study was to have pediatric oncology nurses identify and rate topic priorities for clinical nursing research in the specialty and to determine if nurses in a pediatric cancer center identified different priorities than did nursing colleagues in other settings. The sample consisted of 44 nurses from a comprehensive pediatric cancer center and 43 nurses attending the 12th Annual APON Conference. A decision-making method, the classical Delphi technique, was used. Three rounds of soliciting opinions by questionnaires were completed, and data from each round were reviewed and categorized by a research team of six nurses until group consensus was achieved. The majority of priorities identified by both groups concerned nursing procedures, the pediatric oncology patient, and the specialty itself. The least number of priorities were in the categories of care delivery systems and families. One difference between the two groups was that professional issues dominated the cancer center sample, whereas psychosocial issues were more prominent in the APON sample.