1,255 research outputs found
Dynamics of Diblock Copolymers in Dilute Solutions
We consider the dynamics of freely translating and rotating diblock (A-B),
Gaussian copolymers, in dilute solutions. Using the multiple scattering
technique, we have computed the diffusion and the friction coefficients D_AB
and Zeta_AB, and the change Eta_AB in the viscosity of the solution as
functions of x = N_A/N and t = l_B/l_A, where N_A, N are the number of segments
of the A block and of the whole copolymer, respectively, and l_A, l_B are the
Kuhn lengths of the A and B blocks. Specific regimes that maximize the
efficiency of separation of copolymers with distinct "t" values, have been
identified.Comment: 20 pages Revtex, 7 eps figures, needs epsf.tex and amssymb.sty,
submitted to Macromolecule
Dynamics and fragmentation mechanism of (CH3-C5H4)Pt(CH3)3 on SiO2 Surfaces
The interaction of (CH3-C5H4)Pt(CH3)3
((methylcyclopentadienyl)trimethylplatinum)) molecules on fully and partially
hydroxylated SiO2 surfaces, as well as the dynamics of this interaction were
investigated using density functional theory (DFT) and finite temperature
DFT-based molecular dynamics simulations. Fully and partially hydroxylated
surfaces represent substrates before and after electron beam treatment and this
study examines the role of electron beam pretreatment on the substrates in the
initial stages of precursor dissociation and formation of Pt deposits. Our
simulations show that on fully hydroxylated surfaces or untreated surfaces, the
precursor molecules remain inactivated while we observe fragmentation of
(CH3-C5H4)Pt(CH3)3 on partially hydroxylated surfaces. The behavior of
precursor molecules on the partially hydroxylated surfaces has been found to
depend on the initial orientation of the molecule and the distribution of
surface active sites. Based on the observations from the simulations and
available experiments, we discuss possible dissociation channels of the
precursor.Comment: 18 Pages, 5 Figure
Selection of culture medium and conditions for the production of selenium enriched Saccharomyces cerevisiae
Selenium (Se) yeast is a recognized source of organic food-form of Se and it plays a vital role in animal and human nutrition. The organic Se supplementation in the form of yeast has been shown to have beneficial effects on growth, immune status and reproduction in many animal species, thereby improving the productivity and economical benefits in livestock production. Subsequently, strategies to supplement animal feeds with Se yeast have led to the development of industrial production of Se yeast. The aim of the present study was to improve the yeast biomass production measured as dry cell weight (DCW) and Se enrichment of yeast cells through optimization of the culture conditions and culture media. The culture conditions were optimized by the shake flask experiments. Maximum cell density (2.93 g/LDCW) was observed at pH 5 to 5.5, at 30 °C (2.88 g/L DCW). Significantly higher DCW was recorded when glucose was used as the carbon source (3.09 g/L DCW). The media optimization study carried out in fermentors with five different media (defined medium–A, defined medium-B, synthetic medium, rich medium and industrial medium) showed that the synthetic medium yielded maximum yeast biomass (12.8 g/LDCW) followed by rich medium (11.7 g/L DCW) and defined medium B (10.5 g/LDCW). The Se accumulation was also significantly higher in synthetic medium (2718.3 ppm), followed by industrial medium (2457.7 ppm) and defined medium-B (2251.3 ppm). The methylene blue reduction time (MBRT) was very high ( >15 m) in synthetic medium indicating the highest accumulation of organically bound Se, and MBRT was moderate for defined medium-A and industrial medium ( <10 m).Keywords: Saccharomyces cerevisiae, synthetic medium, carbon source, selenium enrichment, methylene blue reduction time (MBRT)African Journal of Biotechnology Vol. 12(20), pp. 2972-297
Efficient Set Sharing Using ZBDDs
Set sharing is an abstract domain in which each concrete object is represented by the set of local variables from which it might be reachable. It is a useful abstraction to detect parallelism opportunities, since it contains definite information about which variables do not share in memory, i.e., about when the memory regions reachable from those variables are disjoint. Set sharing is a more precise alternative to pair sharing, in which each domain element is a set of all pairs of local variables from which a common object may be reachable. However, the exponential complexity of some set sharing operations has limited its wider application. This work introduces an efficient implementation of the set sharing domain using Zero-suppressed Binary Decision Diagrams (ZBDDs). Because ZBDDs were designed to represent sets of combinations (i.e., sets of sets), they naturally represent elements of the set sharing domain. We show how to synthesize the operations needed in the set sharing transfer functions from basic ZBDD operations. For some of the operations, we devise custom ZBDD algorithms that perform better in practice. We also compare our implementation of the abstract domain with an efficient, compact, bit set-based alternative, and show that the ZBDD version scales better in terms of both memory usage and running time
Role of edaphic factors on VAM fungal colonization and Spore populations in certain tropical wild legumes
Four nodulating annual tropical wild legumes, viz., Alysicarpus monilifer, Desmodium triflorum, Indigofera
linnaei and Tephrosia purpurea from three different regions in the Western Ghats ecosystem were investigated to
assess their mycorrhizal status. The response ofvesicular-arbuscular mycorrhizal (VAM) root colonization and spore
number to edaphicfactors such as soil moisture, pH and available Nand P was analysed. Though the spore number
varied significantly both within and between sites, a uniformly high degree ofroot colonization was observed for all
the plants in the present study. The spore number recorded was high, rangingfrom 15 to 165 spores gl soil. Spores
of sixteen VAM fungal species belonging to Acaulospora, Glomus and Scutellospora were isolated from the
rhizosphere soils.
Soil moisture generally had a positive influence on VAM colonization and sporulation except in I. linnaei.
The pH correlated negatively with root infection in I. linnaei and T. purpurea, but had no influence in the other
two species. The effect of 2-pH on sporulation varied with host species and sites. No general correlation existed
between available soil nutrients, root colonization and spore number but the influence ofNand P was counteractive
on VAM infection. The present study indicates that the response of root colonization and spore number to edaphic
factors is a localised rather than a generalised phenomenon
Polymers pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore
We investigate polymer partitioning from polymer mixtures into nanometer size
cavities by formulating an equation of state for a binary polymer mixture
assuming that only one (smaller) of the two polymer components can penetrate
the cavity. Deriving the partitioning equilibrium equations and solving them
numerically allows us to introduce the concept of "polymers-pushing-polymers"
for the action of non-penetrating polymers on the partitioning of the
penetrating polymers. Polymer partitioning into a pore even within a very
simple model of a binary polymer mixture is shown to depend in a complicated
way on the composition of the polymer mixture and/or the pore-penetration
penalty. This can lead to enhanced as well as diminished partitioning, due to
two separate energy scales that we analyse in detail.Comment: 10 pages, 6 figure
Radiological and Functional Outcome of Retrograde Nailed Humeral Diaphyseal Fracture
INTRODUCTION: Of all fracture of upper limb, the fracture shaft of humerus is relatively
common and easiest to treat. Fracture shaft of humerus accounts for 1% of all
adult fractures. There is wide array of good options for their treatment and there is controversy over best methods for many situations. Appropriate decision making for non-operative or operative treatment depends on a thorough understanding of regional anatomy, fracture pattern (Personality of fracture), Classification and finally factors unique to patient (Personality of patient).
AIM: To study and analyse radiological union, functional
outcome and complications of retrograde unreamed
intramedullary interlocking nailing for treating acute humeral
diaphyseal fractures in adults.
MATERIALS AND METHODS: Our prospective study was from April 2004 to Feb 2006. At our institution, we selected 19 cases of diaphyseal fractures of humerus for this
prospective study. All fresh fractures of the humeral shaft chosen for operative
treatment including isolated fractures and those in polytrauma patients were
nailed in retrograde manner. When there were no clear indications for
operative treatment patients were asked for informed consent for retrograde
nailing.
RESULTS: Out of the 19 patients evaluated, The average hospital stay was 19 days and the mean healing time of a
all fractures was 13.74 weeks. Patients with isolated lesions were in hospital
for a mean of 14 days.
At review, shoulder function was excellent in 17 patients, good in one
patient, fair in one patient, no one in poor grade. Elbow function was excellent
in 14 patients, good in 3 patients, two in fair grade, no one in poor grade.
Total functional out come was excellent in 84% patients, good in 7.8%
patients, fair in 6.5% patient poor grade in 1.31% patient.
CONCLUSION: The concept of biological fixation in terms of unreamed nailing, closed
reduction, static locking and fracture site compression promotes early and
adequate fracture union.
The problem of shoulder impingement and peri-arthritis shoulder,
rotator cuff injury in ante grade nailing are completely avoided with good
functional outcome. It helps in providing early rehabilitation and lessens the morbidity.
Retrograde humeral nailing is better than anterograde nailing and
alternative to plate osteosynthesis for patients with indications for the
operative treatment of fractures of the humeral shaft.
Retrograde nailing is an attractive option in polytrauma, for isolated
fractures which would be difficult to treat conservatively and for patients who
require a rapid functional recovery
Quasiparticles as composite objects in the RVB superconductor
We study the nature of the superconducting state, the origin of d-wave
pairing, and elementary excitations of a resonating valence bond (RVB)
superconductor. We show that the phase string formulation of the t-J model
leads to confinement of bare spinon and holon excitations in the
superconducting state, though the vacuum is described by the RVB state. Nodal
quasiparticles are obtained as composite excitations of spinon and holon
excitations. The d-wave pairing symmetry is shown to arise from short range
antiferromagnetic correlations
Mycorrhizae in sedges as related to root character and its ecological significance
Twenty four sedges were examined to assess the role of root characters on mycorrhizal status. Vesicular-arbuscular
mycorrhizal (VAM) injection was positively related to root thickness and negatively to root hair number and
length. Dried mycorrhizal roots of Bulbostylis barbata, Cyperus cyperinus. C. kyllingia and Fimbristylis ovata
served as inocula oj VAMJungi in pot culture study indicating that mycorrhizal sedge roots could act as inocula
in initiating and reviving mycorrhizae in natural soils
ATTAI VIDAL (LEECH THERAPY) IN SIDDHA SYSTEM OF MEDICINE AND THEIR CURRENT CONCEPT IN THERAPEUTIC APPLICATION - A REVIEW
The Siddha system of medicine is an unique traditional system of medicine practiced in Tamil speaking countries particularly India. In Siddha system of medicine the diseases were treated through internal and external medicine. In external medicine, the leech therapy is one which is used to treat various non-surgical and surgical cases. The leeches have been used for therapeutic purposes since their beginning of civilisation. Ancient Indian, Egyptian, Greek and Arab physicians were used the leeches for wide range of diseases such as inflammatory condition, skin diseases, respiratory disorders, eye diseases, cardiac diseases, urinary and reproductive diseases and dental diseases. The leeches are also used as one of the bloodletting methods in Unani, Ayurveda, and Modern science for various clinical conditions. Recently, researches on leech saliva revealed the presence nearly 100 biologically active compounds such as Hirudin, vasodilators, hyaluronidase, anaesthetics, fibrinases, antibacterial, collagenase etc. The above mentioned pharmacological compounds are injected into human body while sucking of the blood and are responsible for the anaesthetic, anti-inflammatory, anticoagulant and analgesic effect of leech application. In current scenario, the leech therapy is used for various diseases including life threatening diseases such as cardiovascular diseases, cancer, etc. in different system of medicine including modern medicine. Leech therapy is used in plastic and microsurgery as a protective tool against vascular congestion in modern medicine. The Scientific studies on leech saliva were proven and support the leech application in Siddha system of medicine
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