Self-consistent variational theory for globules

A self-consistent variational theory for globules based on the uniform expansion method is presented. This method, first introduced by Edwards and Singh to estimate the size of a self-avoiding chain, is restricted to a good solvent regime, where two-body repulsion leads to chain swelling. We extend the variational method to a poor solvent regime where the balance between the two-body attractive and the three-body repulsive interactions leads to contraction of the chain to form a globule. By employing the Ginzburg criterion, we recover the correct scaling for the $\theta$-temperature. The introduction of the three-body interaction term in the variational scheme recovers the correct scaling for the two important length scales in the globule - its overall size $R$, and the thermal blob size $\xi_{T}$. Since these two length scales follow very different statistics - Gaussian on length scales $\xi_{T}$, and space filling on length scale $R$ - our approach extends the validity of the uniform expansion method to non-uniform contraction rendering it applicable to polymeric systems with attractive interactions. We present one such application by studying the Rayleigh instability of polyelectrolyte globules in poor solvents. At a critical fraction of charged monomers, $f_c$, along the chain backbone, we observe a clear indication of a first-order transition from a globular state at small $f$, to a stretched state at large $f$; in the intermediate regime the bistable equilibrium between these two states shows the existence of a pearl-necklace structure.Comment: 7 pages, 1 figur

TLC Separation of Closely Related Amino Acids

761-76

Hypothalamic control of food intake in cats and monkeys

The role of the central nervous system in regulating food intake was probably suggested first by the discovery that either obesity or emaciation may occur in patients with nervous diseases. For a while these observations were not properly evaluated, because emphasis was laid upon the obesity as such, or the leanness, rather than upon the changed eating habits responsible for the clinical picture. Interest was focused on the hypothalamic region by the experimental studies of many workers (Hetherington, 1941; Hetherington & Ranson, 1940, 1942 a, b; Brobeck, Tepperman & Long, 1943; Kennedy, 1950; Ranson, Fisher & Ingram, 1938) who showed that bilateral lesions in the medial hypothalamus, especially lesions in or ventro-lateral to the ventromedial nucleus, resulted in obesity. The confusion introduced by the notion that pituitary disturbances caused obesity was also clarified by Hetherington (1943), who showed that the hypophysis is in no way directly concerned with the pathogenesis of obesity following injury to the base of brain. Brobeck et al. (1943) demonstrated that this hypothalamic obesity was due to increased food intake (hypothalamic hyperphagia) rather than to disturbances in the fat, carbohydrate or intermediary metabolism. From the time of its discovery this hyperphagia was assumed to be a release phenomenon brought about through the destruction of an inhibitory mechanism.The existence of another mechanism in the lateral hypothalamus of the rat, which controls the 'instinct' or the 'urge' to eat, was demonstrated by Anand & Brobeck (1951 a, b). They showed that bilateral destruction of a well localized area in the lateral hypothalamus, at the same rostro-caudal level as the ventro-medial nucleus, produces complete aphagia and death due to starvation, in spite of the availability of food. It was also observed that of the two mechanisms the lateral one exerts the more basic type of control over food intake and the medial one (inhibitory) produces its effects only when the lateral is intact. The lateral mechanism is designated a 'feeding centre', or even an 'appetite centre', while the medial one is called a 'satiety centre'. Joliffe named the two, together, the 'appestat'. The present study was undertaken to determine, whether similar mechanisms exist in the hypothalamic regions of higher mammals, cats and monkeys, and also whether they are modified by the more highly evolved higher nervous centres

Mineral content of red skinned potatoes of Eastern India

Potato tuber colour is an important factor that influences consumer preferences. Eastern plain region of India contributes about 50% of total potato acreage and production. Consumers in this region generally prefer red skinned varieties. Growing awareness for nutrient rich food can create a niche market for nutritious potatoes. Potato is crop of choice for mineral biofortification owing to better mineral bioavailability due to its high ascorbic acid and minimal phytate content. Iron and zinc are the essentially required minerals for good health. Considering the nutritional importance of these elements and wider prevalence of their deficiency in Indian sub-continent, thirteen Eastern regions red skinned advanced hybrids and varieties were evaluated to find the genetic diversity for iron and zinc content. A significant wide range of contents was observed for both the elements. High heritability of both mineral suggests feasibility of selecting genotypes for breeding nutrient rich varieties. Identified genotypes can be utilised as parental lines for future breeding programme and can be released as nutrient rich potato variety

Titanyl (IV), Zirconyl (IV), Hafnyl (IV) and Uranyl (VI) Complexes of Terdentate Benzoyl Hydrazones

Titanyl(IV), zixconyl(!V), hafnyl(IV) and uranyl(Vl) oomplexes of beniz\u27Dyl hydrazones derti.ved frnm benzoyl hymazdne and sal1cyla1dehyde (BSH), o-hydro!XY acetopheilOllle (BAH), o-hydroxy propi0tphenone (BPH) and 2-hydroxy-1-naphthaldehyde (BNH) are desc·ribed. These complexes were characterised on the basis oof elemental analyses, electrical conductance and spectral (IR, UV and visible) data. The tiltany1\u27(!V) complexes having ·the formula [TiL(OH) (H20) lzO appear ·to have a seven- coordinat·e geometry, the zirconyl and hafnyl complexes, [ML(OHh(H20) )4 (M = Zr or HO appear to possess tetrameric structure in which each metal atom is e.ight-coordina:ted as in the origin,aJl salt, MOCh.8H20 (M = Zr or Hf) ; whereas uranyl comple·xes [UO:J.;(H20hh are dimeric having phenoxide brlidges, •tiu/°\u27u•ti as revealed by the \u27-o,, r:in:g v~br.ations in the IR spectra at ca. 845 cm-1, wi.th each metal atom having an eightcoordinated structure. In all these complexes the benzoyl hydrazones act as di!ba:sic te1r.dentate (N, o-. o-> chelating agentJs

3D-printing: An emerging and a revolutionary technology in pharmaceuticals

© 2018 EDIZIONI MINERVA MEDICA. One of the novel and progressive technology employed in pharmaceutical manufacturing, design of medical device and tissue engineering is three-dimensional (3D) printing. 3D printing technologies provide great advantages in 3D scaffolds fabrication over traditional methods in the control of pore size, porosity, and interconnectivity. Various techniques of 3D-printing include powder bed fusion, fused deposition modeling, binder deposition, inkjet printing, photopolymerization and many others which are still evolving. 3D-printing technique been employed in developing immediate release products, various systems to deliver multiple release modalities etc. 3D printing has opened the door for new generation of customized drug delivery with built-in flexibility for safer and effective therapy. Our mini-review provides a quick snapshot on an overview of 3D printing, various techniques employed, applications and its advancements in pharmaceutical sciences

Corneal nerves in health and disease

The cornea is the most sensitive structure in the human body. Corneal nerves adapt to maintain transparency and contribute to corneal health by mediating tear secretion and protective reflexes and provide trophic support to epithelial and stromal cells. The nerves destined for the cornea travel from the trigeminal ganglion in a complex and coordinated manner to terminate between and within corneal epithelial cells with which they are intricately integrated in a relationship of mutual support involving neurotrophins and neuromediators. The nerve terminals/receptors carry sensory impulses generated by mechanical, pain, cold and chemical stimuli. Modern imaging modalities have revealed a range of structural abnormalities such as attrition of nerves in neurotrophic keratopathy and post-penetrating keratoplasty; hyper-regeneration in keratoconus; decrease of sub-basal plexus with increased stromal nerves in bullous keratopathy and changes such as thickening, tortuosity, coiling and looping in a host of conditions including post corneal surgery. Functionally, symptoms of hyperaesthesia, pain, hypoaesthesia and anaesthesia dominate. Morphology and function do not always correlate. Symptoms can dominate in the absence of any visible nerve pathology and vice-versa. Sensory and trophic functions too can be dissociated with pre-ganglionic lesions causing sensory loss despite preservation of the sub-basal nerve plexus and minimal neurotrophic keratopathy. Structural and/or functional nerve anomalies can be induced by corneal pathology and conversely, nerve pathology can drive inflammation and corneal pathology. Improvements in accuracy of assessing sensory function and imaging nerves in vivo will reveal more information on the cause and effect relationship between corneal nerves and corneal diseases

Formulation and characterization of oral rapid disintegrating tablets of levocetirizine.

BACKGROUND: Levocetirizine, active R (-) enantiomer of cetirizine, is an orally active and selective H1 receptor antagonist used medically as an anti-allergic. Allergic rhinitis is a symptomatic disorder of the nose induced by inflammation mediated by immunoglobulin E (IgE) in the membrane lining the nose after allergen exposure. OBJECTIVES: The purpose of the present study was to prepare rapidly disintegrating tablets of levocetirizine after its complexation with β-cyclodextrin (β-CD). MATERIAL AND METHODS: Levocetirizine-β-CD complex tablets were prepared by direct compression technique using 3 synthetic superdisintegrants in different proportions. Development of the formulation in the present study was mainly based on the concentration of superdisintegrants and the properties of the drug. Nine batches of tablets were formulated and evaluated for various parameters: drug content, weight variation, water absorption ratio, wetting time, in vitro disintegration, hardness, friability, thickness uniformity, and in vitro dissolution. RESULTS: A Fourier-transform infrared spectroscopy (FTIR) study showed that there were no significant interactions between the drug and the excipients. The prepared tablets were good in appearance and showed acceptable results for hardness and friability. The in vitro disintegrating time of the formulated tablet batches was found to be 15-35 s percentage and the drug content of tablets in all formulations was found to be between 90-102%, which complied with the limits established in the United States Pharmacopeia. CONCLUSIONS: Complexation of levocetirizine with β-CD significantly improves the solubility of the drug. The disintegration time of the tablets was decreased with an increase in superdisintegrant amount. The tablets (batch CPX5) had a minimum disintegration time of 20 s and 99.99% of the drug was released within 10 min