Role of Epstein-Barr virus in fine-needle aspirates of metastatic neck nodes in the diagnosis of nasopharyngeal carcinoma

The crystal structure of the peptide Boc-Phe-Val-OMe determined by X-ray diffraction methods is reported in this paper. The crystals grown from aqueous methanol are orthorhombic, space group P2(1)2(1)2(1),a = 11.843(2), b = 21.493(4), c = 26.676(4) A3 and V = 6790 A3. Data were collected on a CAD4 diffractometer using MoK alpha radiation (lambda = 0.7107 A) up to Bragg angle theta = 26 degrees. The structure was solved by direct methods and refined by a least-squares procedure to an R value of 6.8% for 3288 observed reflections. There are three crystal-lographically independent peptide molecules in the asymmetric unit. All the three molecules exhibit extended conformation. The sidechain of the Val2 residue shows two different conformations. The conformation of the peptide Boc-Phe-Val-OMe is compared with the conformation of Ac-delta Phe-Val-OH. It is observed that while Boc-Phe-Val-OMe exhibits an extended conformation, Ac-delta Phe-Val-OH shows a folded conformation. The results of this comparison highlight the conformation constraining property of the delta Phe residue. Interestingly, even though Boc-Phe-Val-OMe and Ac-delta Phe-Val-OH are conformationally different, they exhibit similar packing patterns in the solid state.     

Strain compensated InGaAs-GaAsP-InGaP laser

The performance characteristics of InGaAs-GaAsP-InGaP strain compensated laser emitting near 1 /spl mu/m are reported. The ridge waveguide lasers have room temperature threshold current of 18 mA and differential quantum efficiency of 0.45 W/A/facet. The linewidth enhancement factor is smaller and gain coefficient is larger for these strain compensated lasers compared to that for conventional strained layer laser. This may be due to higher effective compressive strain in the light emitting layer of these devices which reduces the effective mass. The observed larger gain coefficient is consistent with the measured larger relaxation oscillation frequency of these lasers compared to that for a conventional strained layer laser.     

Is simplicity the key to engagement for children on the autism spectrum?

This article presents a conceptualisation of technologies as simple, ambient forms. By avoiding the tendency to solve problems and by being open to interaction that emerges through repetition and flow, we argue that technology can offer more for people than functionality. When the user is given freedom to discover control without burdensome cognitive demands and the fear of failure, even everyday technologies can arouse curiosity and thus reveal untapped ability. What is unique about our work is its therapeutic application as a medium for engaging the most hard to reach children on the autism spectrum. Our theoretical foundations are drawn from the human–computer interaction paradigm of tangible interaction. This is of interest to us as a framework for the study of the physical and sensory manipulation of information. For children with cognitive and developmental delays, discovering a close match between physical control and digital response has proved both rewarding and motivating. The significance of this is illustrated through a range of studies undertaken with children with autism spectrum disorders. These include a mixed group attending a holiday club, a study that introduced keyboard activities to children with poor receptive communication and a case study using an ordinary microphone. The research captures emergent, exploratory interaction with a software application called ReacTickles. The case study uses a specifically customised video coding technique to analyse idiosyncratic interactions that demonstrate the impact of simple, playful interaction on self-esteem and creativity.     

Web evolution and Web Science

This paper examines the evolution of the World Wide Web as a network of networks and discusses the emergence of Web Science as an interdisciplinary area that can provide us with insights on how the Web developed, and how it has affected and is affected by society. Through its different stages of evolution, the Web has gradually changed from a technological network of documents to a network where documents, data, people and organisations are interlinked in various and often unexpected ways. It has developed from a technological artefact separate from people to an integral part of human activity that is having an increasingly significant impact on the world. This paper outlines the lessons from this retrospective examination of the evolution of the Web, presents the main outcomes of Web Science activities and discusses directions along which future developments could be anticipated.     

Single amino acid substitutions can further increase the stability of a thermophilic L-lactate dehydrogenase

Lactate dehydrogenases are of considerable interest as stereospecificcatalysts in the chemical preparation of enantiomerically pure-hydroxyacid synthons. For such applications in synthetic organicchemistry it would be desirable to have enzymes which tolerateelevated temperatures for prolonged reaction times, to increaseproductivity and to extend then applicability to poor substrates.Here, two examples are reported of significant thermostabilizations,induced by sitedirected mutagenesis, of an already thermostableprotein, the L-lactate dehydrogenase (EC 1.1.1.27 [EC] , 35 kDa permonomer subunit) from Bacillus stearothermophilus. Thermal inactivationof this enzyme is accompanied by irreversible unfolding of thenative protein structure. The replacement of Argl71 by Tyr stabilizesthe enzyme against thermal inactivation and unfolding. Thisstabilizing effect appears to be based on improved interactionsbetween the subunits in the core of the active dimeric or tetramericforms of the enzyme. The thermal stability of L-lactate dehydrogenasevariants with an active site Arg residue, either in the 171(wild-type) or in the 102 position, is further increased bysulfate ions. The two stabilizing effects are additive, as foundfor the Argl71Tyr/ Gln1O2Arg double mutant, for which the stabilityof the protein in 100 mM sulfate solution reaches that of L-lactatedehydrogenases from extreme thermophiles. All mutant proteinsretain significant catalytic activity, both in the presenceand absence of stnhilfoing salts, and are viable catalysts inpreparative scale reactions.     

Effect of potassic and phosphatic fertilizer type, fertilizer Cd concentration and zinc rate on cadmium uptake by potatoes

In some areas of southern Australia, cadmium (Cd) concentrations in excess of the Australian maximum permitted concentration (0.05 mg kg^–1 fresh weight) have been found in tubers of commercially grown potato (Solanum tuberosum L.) crops. Field experiments were therefore conducted in various regions of Australia to determine if Cd uptake by potatoes could be minimised by changes in either phosphorus (P), potassium (K) or zinc (Zn) fertilizer management.Changing the chemical form in which either P fertilizer (monoammonium phosphate, diammonium phosphate, single superphosphate and reactive rock phosphate) or K fertilizer (potassium chloride and potassium sulfate) were added to crops had little influence on tuber Cd concentrations. Fertilizer Cd concentrations also had little influence on tuber Cd concentrations, suggesting that residual Cd in the soil was a major contributor to Cd uptake by the crops on these soils.Addition of Zn at planting (up to 100 kg Zn ha^–1) significantly reduced tuber Cd concentrations at four of the five sites studied. However, the largest variation was between sites rather than between treatments, with site mean tuber Cd concentrations varying tenfold (from 0.018 to 0.177 mg Cd kg^–1 fresh weight). Factors associated with irrigation water quality at the sites, in particular the chloride concentration, appeared to dominate any effects of changing fertilizer type or Cd concentration.     

Modeling the tensile behavior of fiber bundles with irregular constituent fibers

In this article, the effect of fiber dimensional irregularities on the tensile behavior of fiber bundles is modeled with the finite element method. The fiber dimensional irregularities are simulated with sine waves of different magnitudes. The specific‐stress/strain curves of fiber bundles and their constituent single fibers are obtained and compared. The results indicate that fiber diameter irregularity along the fiber length has a significant effect on the tensile behavior of fiber bundles. For a bundle of uniform fibers of different diameters, all the constituent fibers will break simultaneously, regardless of the fiber diameter. Similarly, if fibers within a bundle have the same pattern and level of diameter irregularity along the fiber length, the fibers will break at the same time, also regardless of the difference in the average diameter of each fiber. In these cases, the specific‐stress/strain curve for the bundle overlaps with that of the constituent fibers. When a fiber bundle consists of single fibers with different levels of diameter irregularities, the specific‐stress/strain and load–elongation curves of the fiber bundle have a stepped or ladder shape. The fiber with the highest irregularity breaks first, even when the thinnest section of the fiber is still coarser than the diameter of a very thin but uniform fiber in the bundle. This study suggests that fiber diameter irregularity along the fiber length is a more important factor than the fiber diameter itself in determining the tensile behavior of a fiber bundle consisting of irregular fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2664–2668, 2004     

Poly(ethylene oxide)/Laponite nanocomposites via melt-compounding: effect of clay modification and matrix molar mass

The present study focuses on the preparation of poly(ethylene oxide) (PEO) nanocomposites based on the synthetic Laponite clay. The clay was added both in its pure form as well as organically modified with low molar mass poly(ethylene glycol) (PEG) components in order to enhance the compatibility between Laponite and PEO. Several PEG's with different end groups were used. Almost all of them were found to intercalate in the clay intergallery spacing. An order of intercalation efficiency could be established. The modified clays displayed a good thermal stability at the nanocomposite processing temperature.The nanocomposites based on the pure Laponite clay as well as the modified clays display an intercalated structure with a modest intergallery spacing. The ion-dipole modification with the PEG's was ineffective in improving the compatibility between PEO and the Laponite silicate layers. Their respective mechanical properties were found to be increased a little, which can be attributed to the low effective aspect ratio of the silicate platelets present in the nanocomposites. This is caused by the low initial aspect ratio of Laponite (w/t=25) and the limited basal spacing increase. The addition of clay does not result in nucleation of the PEO crystallisation. In contrast, the crystallisation was inhibited, resulting in decreased heat of fusions, especially for the pure Laponite nanocomposites. The nanocomposites based on the modified Laponites display a good thermal stability.     

Toughened electrospun nanofibers from crosslinked elastomer‐thermoplastic blends

A crosslink‐able elastomeric polyester urethane (PEU) was blended with a thermoplastic, polyacrylonitrile (PAN), and electrospun into nanofibers. The effects of the PEU/PAN ratio and the crosslinking reaction on the morphology and the tensile properties of the as‐spun fiber mats were investigated. With the same overall polymer concentration (9 wt %), the nanofiber containing higher composition of PEU shows a slight decrease in the average fiber diameter, but the tensile strength, the elongation at break and tensile modulus of the nanofiber mats are all improved. These tensile properties are further enhanced by slight crosslinking of the PEU component within the nanofibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Low‐velocity impact of nanocomposite and polymer plates

Nanocomposites are more widely studied today because of higher stiffness, decreased permeability, thermal stability, and many other properties superior to those of regular polymers. However, manufacturers are concerned about implementing nanocomposites because of their lower impact properties with respect to the base polymer. This study focused on low‐velocity impact tests of a thermoplastic olefin by itself and with 5 wt % nanoclay. The impact tests were conducted at ?40, 23.9, and 65.6°C until the polymer and nanocomposite plates experienced complete striker penetration. The force–time and force–deflection responses obtained from the impact testing provided a means of comparing the impact performances of the two materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2309–2315, 2005