Grafting of titanium dioxide microspheres with a temperature‐responsive polymer via surface‐initiated atom transfer radical polymerization without the use of silane coupling agents

Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO₂ microparticles via a straightforward controlled surface‐initiated polymerization method.     

Vocational training in the use of new technologies for people with disabilities

Following a brief review of the literature, details are given of an in-depth evaluation of a computer training centre called Microjob. This facility set out to integrate computer training, vocational guidance, functional assessment, placement in employment and post-placement support into a single service delivery package. In this paper the facility's outcome record is examined in relation to targets set for it, consideration is given to the special needs of home-based trainees, and specific difficulties faced by the project (including an inefficient management structure, inadequate staff training and a poor level of awareness of clients' special needs) are discussed.     

Quantification of Doublet Vector Distribution of Granular Materials

Soil fabric quantities such as doublet vector and branch vector distributions are important in doublet mechanics and micromechanics modeling of soil behavior. The quantification of these quantities is therefore imperative in applying and verifying these modeling techniques. This paper presents the development of a new method to quantify the doublet distribution of granular assemblies and some experimental results. The method treated doublet vectors as random vectors and built up the integrated distribution function from the distribution functions of the projections of the random vectors in the three orthogonal subspaces. A mechanism to evaluate the doublet vector distribution from sectional images was developed for the case of granular assemblies composed of spherical or subspherical particles. A procedure was also developed to assess the integrated distribution function through evaluating the projection distribution functions in two orthogonal subspaces for the case of axial-symmetric distribution of doublet vectors of spherical particles. The comparison of the doublet distribution of a dense Ottawa sand specimen, quantified by the proposed procedure, with Oda's experimental observations on contact normal distributions indicated a qualitative consistency. Doublet distribution of spherical assemblies is the same as the branch vector distribution and the contact normal distribution when the nearest neighbors are in contact, and therefore can be applied in both doublet mechanics and micromechanics modeling. The developed procedure is not scale-dependent and can be used to quantify these distributions of particulate materials in different length scales.     

Three minutes to tomorrow [My First Job]

Ray Floyd looks back at his 54-year career and provides advice to those just starting their careers.     

Macrocyclization of Organo‐Peptide Hybrids through a Dual Bio‐orthogonal Ligation: Insights from Structure–Reactivity Studies

Macrocycles constitute an attractive structural class of molecules for targeting biomolecular interfaces with high affinity and specificity. Here, we report systematic studies aimed at exploring the scope and mechanism of a novel chemo‐biosynthetic strategy for generating macrocyclic organo‐peptide hybrids (MOrPHs) through a dual oxime‐/intein‐mediated ligation reaction between a recombinant precursor protein and bifunctional, oxyamino/1,3‐amino‐thiol compounds. An efficient synthetic route was developed to access structurally different synthetic precursors incorporating a 2‐amino‐ mercaptomethyl‐aryl (AMA) moiety previously found to be important for macrocyclization. With these compounds, the impact of the synthetic precursor scaffold and of designed mutations within the genetically encoded precursor peptide sequence on macrocyclization efficiency was investigated. Importantly, the desired MOrPHs were obtained as the only product from all the different synthetic precursors probed in this study and across peptide sequences comprising four to 15 amino acids. Systematic mutagenesis of the “i?1” site at the junction between the target peptide sequence and the intein moiety revealed that the majority of the 20 amino acids are compatible with MOrPH formation; this enables the identification of the most and the least favorable residues for this critical position. Furthermore, interesting trends with respect to the positional effect of conformationally constrained (Pro) and flexible (Gly) residues on the reactivity of randomized hexamer peptide sequences were observed. Finally, mechanistic investigations enabled the relative contributions of the two distinct pathways (side‐chain→C‐end ligation versus C‐end→side‐chain ligation) to the macrocyclization process to be dissected. Altogether, these studies demonstrate the versatility and robustness of the methodology to enable the synthesis and diversification of a new class of organo‐peptide macrocycles and provide valuable structure–reactivity insights to inform the construction of macrocycle libraries through this chemo‐biosynthetic strategy.     

Marital interaction of agoraphobic women: A controlled, behavioral observation study.

Married couples with a female agoraphobic spouse (n = 22) were compared with demographically similar community control couples (n = 21) on self-report and observational measures of marital interaction. Consistent with hypotheses, husbands of agoraphobic women were more critical of their wives than were control husbands, and clinical couples were less likely to engage in positive problem solution than control couples. Contrary to hypothesis, clinical husbands were not less supportive than control husbands. Where general measures of marital distress were concerned, clinical couples, relative to control couples, evinced more distress by self-report, by their higher rate of negative nonverbal behavior, and by their longer sequences of negative exchanges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clonal stability in late-relapsing childhood lymphoblastic leukaemia

We report stability of a clonal immunoglobulin heavy chain (IgH) gene rearrangement in a case of childhood acute lymphoblastic leukaemia (ALL) relapsing 17 years after completion of first-line therapy. Clonal stability was shown by polymerase chain reaction amplification of the hypervariable CDRIII region of IgH gene. Identically sized products from the original diagnostic and the second presentation samples were obtained and direct sequencing confirmed complete sequence homology. Absence of clonal evolution together with recent reports of persistent minimal residual disease in patients in long-term complete remission, suggests that 'cure' of childhood ALL may be critically dependent on effective immune surveillance to keep such disease below clinically significant levels.     

Cardiovascular effects of microinjections of opioid agonists into the ''Depressor Region'' of the ventrolateral periaqueductal gray region

Differentiating the binding properties of applied lectins should facilitate the selection of lectins for characterization of glycoreceptors on the cell surface. Based on the binding specificities studied by inhibition assays of lectin-glycan interactions, over twenty Gal and/or GalNAc specific lectins have been divided into eight groups according to their specificity for structural units (lectin determinants), which are the disaccharide as all or part of the determinants and of GalNAc alpha 1-->Ser (Thr) of the peptide chain. A scheme of codes for lectin determinants is illustrated as follows: (1) F (GalNAc alpha 1-->3GalNAc), Forssman specific disaccharide--Dolichos biflorus (DBL), Helix pomatia (HPL) and Wistaria floribunda (WFL) lectins. (2) A (GalNAc alpha 1-->3 Gal), blood group A specific disaccharide--Codium fragile subspecies tomentosoides (CFT), Soy bean (SBL), Vicia villosa-A4 (VVL-A4), and Wistaria floribunda (WFL) lectins. (3) Tn (GalNAc alpha 1-->Ser (Thr) of the protein core)--Vicia villosa B4 (VVL-B4), Salvia sclarea (SSL), Maclura pomifera (MPL), Bauhinia purpurea alba (BPL) and Artocarpus integrifolia (Jacalin, AIL). (4) T (Gal beta 1-->3GalNAc), the mucin type sugar sequences on the human erythrocyte membrane(T alpha), T antigen or the disaccharides at the terminal nonreducing end of gangliosides (T beta)--Peanut (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera (MPL), Sophora japonica (SJL), Artocarpus lakoocha (Artocarpin) lectins and Abrus precatorius agglutinin (APA).(5) I and II (Gal beta 1-->3(4)GlcNAc)--the disaccharide residue at the nonreducing end of the carbohydrate chains derived from either N- or O-glycosidic linkage--Ricinus communis agglutinin (RCA1), Datura stramonium (TAL, Thorn apple), Erythrina cristagalli (ECL, Coral tree), and Geodia cydonium (GCL). (6) B (Gal alpha 1-->3Gal), human blood group B specific disaccharide--Griffonia(Banderiaea) simplicifolia B4 (GSI-B4). (7) E (Gal alpha 1-->4Gal), receptors for pathogenic E. coli agglutinin, Shiga toxin and Mistletoe toxic lectin-I (ML-I) and abrin-a.     

THE ORIGIN OF BEDDED PENNSYLVANIAN FIRE CLAYS IN THE UNITED STATES1

The bedded Pennsylvanian fire clays are practically all formed in the Pottsville and Allegheny series, and are associated more or less closely with coal beds, although all underclays are not refractory. Various theories have been advanced to explain the origin of these fire clays, but there seem to be serious objections to most of them. The author believes that the clays here discussed were mostly deposited in swamps and owe their purity to the leaching action of waters containing carbonic and organic acids, which leached out the iron, alkalis, etc. Such leaching would occur chiefly in those portions of the swamp where the water was circulating along channels. Differential leaching would therefore explain variable composition in the underclays.