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CuInS2 (CIS) quantum dots (QDs) with different diameters were prepared and their optical properties were studied. The optical band gap of QDs, as estimated by absorption spectrum, was found to decrease with increase in size. The stokes shift between absorption and photoluminescence peaks was observed to be larger (>100 meV) in all the three samples. This shows that the defect states available in the forbidden gap dominates the recombination mechanism. The variation in the emission peak with QD size, however, indicates that the relaxation dynamics in CIS QDs involves both excitonic level as well as the defect states.
1. Animals susceptible and naturally immune to plague—Bombay rats and white mice—were infected with Past, pestis and supravital study of white blood cells from the peripheral blood stream carried out. Similar studies were made on white mice injected with (a) pure envelope serum, (b) pure somatic serum, and (c) whole antiplague serum.
2. Different experimental conditions produced different cell pictures with different behaviours of individual cell types, especially the polymorpho-nuclears, the monocytes and the clasmatocytes. These abnormalities were found to bear distinctive relationship to (a) active immunity, (b) passive immunity, and (c) susceptibility on the part of the experimental animal.
3. The value of immunological inferences from this study in relation to plague-serum therapy and plague prophylaxis has been emphasized.
4. The possibility of a better understanding of host-parasite relationships from similar studies in other bacterial infections has been pointed out.
Our thanks are due to Lt.-Col. S. S. Sokhey, I.M.S., Director Haffkine Institute, for his interest in this investigation.
1. The description of a strain which behaves as a pure Vi variant of S. typhi is given. Complete absence of H antigen from it is demonstrated. The non-interference in its Vi agglutinating activity by the very small amount of O antigen contained in it is shown. This strain has been designated “Vi 1”.
2. With the help of this strain, the practical applicability of Vi agglutination as a reliable method for the routine serological diagnosis of typhoid infection and for the detection of typhoid carrier condition, in preference to O and H types of agglutination, is stressed.
The unstable domain in the (k, Ø) plane for oblique modulation of ion-acoustic waves, in a two-electron-temperature plasma, is investigated using the KBM perturbation technique. It is shown that, in a collisionless plasma, the maximum growth rate for the modulational instability, for large carrier-wave amplitudes (a0 ≳ 0·1), exceeds the electron Landau damping rate for sufficiently oblique modulation.
In Copper back-end-of-line (BEOL), the “punchthru™ process” – removal of barrier material from via bottom during etch/re-sputter step, and gouging into the underlying Copper line - has been increasingly used in 65nm production for its superior reliability. However, with the adoption of porous low-k dielectric at 45nm node and beyond, the conventional punchthru process can cause physical damage to the porous dielectric, such as roughening of the trench bottom in dual damascene structures, micro-trenching in the bottom of single trenches, which may have reliability implications. This paper reported on the use of off-angular Tantalum neutral flux during the re-sputter process to improve the selectivity between the via and trench bottom in order to protect the trench bottom and via bevel, while still allowing sufficient gouging into the underlying Copper line. In addition, the plasma density and ion energy are adjusted to further optimize selectivity, and to eliminate any micro-trenching. Therefore, this paper demonstrated PVD high deposit/etch selectivity process based on transmission-electron microscopy (TEM) and studies of electrical test result. This approach has extended the PVD Tantalum barrier process to at least 32nm node.
A method for patterning biomolecules using electron beam (e-beam) lithography has been developed. First, a non-biofouling poly (ethylene glycol) terminated self-assembled monolayer (SAM) was deposited on a silicon oxide substrate. This SAM was then ablated by e-beam to create patterns aligned with the pre-existing features on the wafer. Aldehyde-terminated polyamidoamine (PAMAM) dendrimers were assembled in a layer-by-layer fashion in the ablated patterns to allow the covalent immobilization of oligonucleotide probes. The aminated oligonucleotides were attached using Schiff base chemistry followed by reductive amination. The functionality of the attached oligonucleotides was demonstrated by the hybridization of fluorescently labeled complementary target oligonucleotides. The hybridized target oligonucleotides could be stripped and the regenerated surface bound probe oligonucleotides could be rehybridized with complementary target oligonucleotide.
Objective: This retrospective study aims to describe the airway management and benefits of nasotracheal intubation over tracheostomy in 260 patients with oral cancer undergoing surgery. Methods and Results: The medical records of 260 patients undergoing surgery for oral cancer were reviewed for airway management during the perioperative period. Eighteen patients had previous surgery for oral cancer and were scheduled for flap reconstruction, recurrence or other complications. In 28 cases neck movement was restricted and decreased mouth opening was found in 50% of all patients because of a large growth or fixation of tissues of head and neck, oral cavity, pharynx or larynx by tumour, or radiation fibrosis. In 53 patients intubation was undertaken under spontaneous ventilation. In 20 cases the trachea was extubated in the immediate postoperative period. In 220 cases patients were extubated next morning in the intensive care unit. In none of the cases was elective tracheostomy under local anaesthesia performed before surgery for the maintenance of the airway for anaesthesia. Elective tracheostomies were done in 17 cases. Three patients remained intubated for 24–48 h because of a high suspicion of airway obstruction following extubation due to a large pectoralis major flap. These three patients received a tracheostomy because of increased oropharyngeal and laryngeal oedema. In three cases emergency tracheostomies were performed due to upper airway obstruction after extubation and in one case prolonged elective ventilation was required due to severe chest infection. Conclusion: Oral cancer patients have a potentially difficult airway but, if managed properly during perioperative period, morbidity and mortality can be reduced or avoided. Oral cancer patients can be managed safely without the routine use of a tracheostomy. Nasotracheal intubation is a safe alternative to tracheostomy in oral cancer patients except in some selected patients.
Radio and X-ray studies of young supernovae probe the interaction between the supernova shock waves and the surrounding medium and give clues to the nature and past of the progenitor star. Here we discuss the early emission from type Ic SN 2002ap and argue that repeated Compton boosting of optical photons by hot electrons presents the most natural explanation of the prompt X-ray emission. We describe the radio spectrum of another type Ic SN 2003dh (GRB030329) obtained with combined GMRT and VLA data. We report on the low frequency radio monitoring of SN 1995N and our objectives of distinguishing between competing models of X-ray emission from this SN and the nature of its progenitor by X-ray spectroscopy. Radio studies on SN 2001gd, SN 2001ig and SN 2002hh are mentioned.
Syntheses carried out on soluble polymers, such as polyethylene glycol (PEG), benefit the advantages of both solution-phase and solid-phase syntheses. The choice of the reaction solvent governs the polymer solubility. Synthetic steps are conducted under homogeneous conditions whereas purifications are performed by filtration after polymer precipitation. This alternative strategy, known as liquid-phase chemistry, has been investigated to prepare combinatorial libraries.
The fact that soluble polymer supported molecules are directly amenable to standard spectroscopic methods, including NMR (1H, 13C) and ESI or MALDI mass spectrometry (ElectroSpray and Matrix Assisted Laser Desorption Ionization) allows to perform to in situ reaction monitoring without the need to release the compound from the polymeric support.
We report a general methodology to characterize step by step soluble polymer supported organic molecules by MALDI and ESI mass spectrometry. High throughput analyses were targeted to fullfil combinatorial chemistry requirements. Data acquisition and interpretation were automated through the design of specific experimental protocols and a data managment software. MALDI mass spectrometry was appropriate to analyze pure supported molecules whereas ESI mass spectrometry coupled to liquid chromatography was required to unravel PEG mixtures.
Tissues are characterized by highly distinctive microarchitecture and overall form that are critical to tissue specific function. with increasing interest in tissue engineering to create surrogates for human tissues and organs, innovative techniques have been developed to generate scaffolds that display form, and microarchitecture mimicking physiological structures. While this artifice may generate pre-programmed shapes, it fails to take advantage of the inherent ability of cells to organize themselves and their surroundings. The generation of mechanical forces by the cellular cytoskeleton plays a critical role in the organization of matrix and of cellular colonies. The anchorage of the cytoskeleton to a substrate is essential for cellular tractional processes. in tissues, cells are anchored in a stationary, 3-D network of collagen in a highly characteristic spatial arrangement. This spatial order arises from vectorial deposition of matrix and its subsequent tractional organization by cells. The junction of the cell binding domain of collagen with specific integrin receptors, and the cells’ cytoskeleton comprises the apparatus for the interconversion of mechanical and biochemical energy.
Type I collagen comprises between 75-95% of the stationary extracellular matrix of most tissues, forming a continuum in which most of the static cells are anchored. Collagen serves as the track for haptotactic cell migration. The junction between collagen, its receptor integrins, and the cells’ cytoskeleton plays a crucial role in cell differentiation and morphogenesis by serving as the agent for transducing mechanical forces into chemical and biochemical work. The physiological, functional organization of collagen is the solid state in the form of a network of fibers. The only molecules available for engaging the receptors are those located on the fiber surface. Cryogenic scanning force microscopy (SFM) of single molecules of collagen allowed us to correlate surface features with known sequence and stereochemical markers within collagen. Theoretical conformational studies to locate markers for intermolecular recognition and allosteric binding showed that collagen a 1(1) chain residues 766GTPGPQGIAGQRGVV780 generate a distinctive conformation, characterized by a relatively stable (3-bend at the core (Fig. 1) within the triple helical polyproline II conformation extant in the rest of the molecule (1).
An artificial diet developed for the rice leaffolder, Cnaphalocrocis medinalis was used in a bioassay of endotoxin proteins from Bacillus thuringiensis (Bt) strains and plant-derived protease inhibitors against the leaffolder, C. medinalis, and the yellow stemborer, Scirpophaga incertnlas. Of the 14 samples of endotoxins derived from different strains of Bt (sub-species kurstaki and sphericus) tested, 5 samples — BT 29, BT 47, BT 61, BT 70 and HD-1— were effective against leaffolder larvae in preliminary tests. Subsequent tests indicated HD-1 to be the most effective against the leaffolder, followed by BT 61 and BT 70, with non-overlapping 95% fiducial limits of LC50 values (3.9,18.2 and 41.1 mg protein/kg diet, respectively). Mortality was observed after 48 h of release of neonate larvae. In contrast, the two protease inhibitors tested, namely soybean trypsin inhibitor (SBTI) and jackfruit seed trypsin inhibitor (JSTI) were less lethal to the two pests. The latter was more effective against the yellow stemborer at much lower concentrations.
The viability of metacercariae of Fasciola gigantica was tested by in vitro and in vivo methods. In vitro testing was based upon the motility of juvenile flukes within the inner cyst as examined under the light microscope. In vivo testing was undertaken through experimental infections of rabbits (two groups) and natural definitive hosts, lambs (one group). In the first group, out of six rabbits each given 25 metacercariae, worm establishment only took place in one rabbit with a single fluke recovery on 60 days post infection. In the second group of six rabbits each given 200 metacercariae, five were infected, with two or three flukes per host. All the lambs given 250 metacercariae became infected showing prevalences of 7.2–40% in comparison with rabbits in which low prevalences (0–4%) were recorded. The results indicated that even viable metacercariae which were already tested in vitro could not readily establish in rabbits. Such variability in worm establishment suggests that immunological and chemotherapeutic studies in rabbits infected with F. gigantica are likely to be unreliable.
A two timescale stochastic approximation scheme which uses coupled iterations is used for simulation-based parametric optimization as an alternative to traditional “infinitesimal perturbation analysis” schemes. It avoids the aggregation of data present in many other schemes. Its convergence is analyzed, and a queueing example is presented.
The flow of chemical and mechanical signals among cells, and between cells and their environment plays a crucial role in cell differentiation and morphogenesis. In tissues, type I collagen serves as the template for cell anchorage and migration, and it mediates the flux of regulatory signals via highly specific receptors. Cells respond to mechanical cues by secreting growth factors and remodeling their surrounding matrix in an exquisitely orchestrated spatial and temporal program of matrix turnover and organization. Cellular tractional forces contribute to the organization and orientation of the newly synthesized matrix, establishing the template for subsequent morphogenesis. The junction between cells and collagen plays a key role in cell differentiation, morphogenesis and tissue remodeling. An optimal biomimetic environment would emulate this pathway for the exchange of stimuli. To achieve this goal, we have constructed templates which place cells in apposition to P-15, a synthetic peptide ligand for collagen receptors. These environments prompted 3-D colony formation, induced increased osteogenic differentiation, and the deposition of highly oriented and organized matrix by human dermal and gingival fibroblasts and by osteoblast like HOS cells. These observations support our concept for biomimetic environments for tissue engineering.
Current methods for correcting articular cartilage defects are limited by a scarcity of cartilage cells. Here we describe a novel method for the conversion of human dermal fibroblasts to chondrocyte-like cells and the potential application of this methodology to cartilage tissue engineering. Human neonatal foreskin fibroblasts were seeded on two-dimensional, tissue culture polystyrene (TCPS) in high density micromass cultures in the presence of staurosporine (50-200 nM), a protein kinase C (PKC) inhibitor, and lactic acid (40 mM) to induce functional hypoxia. Dermal fibroblasts were similarly cultured on three-dimensional polymer scaffolds composed of a non-woven polyglycolic acid (PGA) fiber mesh reinforced in a dilute solution of poly(L-lactic acid) (PLLA). At 24 hours, northern analysis revealed a staurosporine dose-dependent increase in aggrecan core protein expression in lactate-treated micromass cultures on TCPS, while type I collagen gene expression was virtually abolished in all cultures supplemented with staurosporine. The cells in these cultures displayed a rounded, cobblestone-shaped morphology typical of differentiated chondrocytes (most pronounced at 200 n.M staurosporine and 40 mM lactate), and were organized into nodules which stained positively with Alcian blue. When seeded on PGA/PLLA matrices under identical conditions as described for TCPS, a chondrocyte-like morphology was observed in cultures treated with lactate and staurosporine in contrast to the flattened sheets of fibroblast-like cells seen in untreated controls. Taken together, the above findings suggest that staurosporine treatment coupled with high density micromass culture in the presence of lactate induces chondrogenic differentiation in human dermal fibroblasts, and that these cells may be used in concert with three-dimensional polymer scaffolds for the repair of articular cartilage lesions.
A two–time scale stochastic approximation algorithm is proposed for simulation-based parametric optimization of hidden Markov models, as an alternative to the traditional approaches to “infinitesimal perturbation analysis.” Its convergence is analyzed, and a queueing example is presented.