Graft copolymerization of hydroxyethyl methacrylate onto chitosan

Chitosan is a polysaccharide derived from chitin, which is commonly found in shellfish waste materials. The present work is concerned with the graft copolymerization of 2-hydroxyethylmethacrylate (HEMA) onto chitosan using thiocarbonation–potassium bromate for redox initiation. The combined effects of the principal reaction variables for the grafting reaction were studied systematically. This grafting reaction was studied with respect to percentages of graft yield (%G.Y.), homopolymer (%H.P.), and total conversion (%T.C.). A tentative polymerization mechanism is proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 683–702, 2001     

Rate control of elastic connections competing with long-rangedependent network traffic

Long-range dependence is regarded as a fundamental property of network traffic. Using an original approach, we incorporate this property in a traffic control mechanism for elastic connections that can adapt to the instantaneous network load in a differentiated services-type framework. In this scenario, the network makes predictions of bandwidth requirements of the high-priority traffic and returns feedback information to the elastic source. We include a prediction compensation algorithm that compensates for the larger prediction errors for connections with longer roundtrip delay, and analyze the performance of this algorithm. The specific topology involved in traffic control for differentiated services is thus harnessed, together with the long-range dependence, to improve network performance, thereby counteracting the undesirable characteristics of self-similarity. Furthermore, an adaptive version of the rate-based control algorithm is studied, based on the use of real-time estimates of traffic parameters, including the mean, variance, and Hurst parameter     

Biological motor control

The authors consider understanding what it will take for robots to run with the cockroaches. Nature has designed an elegant architecture that solves a number of engineering problems related to motor control. The neurobiological system utilizes large, parallel structures of repeatable elements to ensure maximum reliability. The motoneurons and muscle units interact to produce a diverse set of movements with a single architecture. This architecture guarantees efficient use of the muscle fibers while simplifying the control requirements. These biologically inspired principles can be applied to both electrical and bioengineering systems to solve real-world problems     

LINC01133 Inhibits Invasion and Promotes Proliferation in an Endometriosis Epithelial Cell Line

Endometriosis is a common gynecological disorder characterized by ectopic growth of endometrium outside the uterus and is associated with chronic pain and infertility. We investigated the role of the long intergenic noncoding RNA 01133 (LINC01133) in endometriosis, an lncRNA that has been implicated in several types of cancer. We found that LINC01133 is upregulated in ectopic endometriotic lesions. As expression appeared higher in the epithelial endometrial layer, we performed a siRNA knockdown of LINC01133 in an endometriosis epithelial cell line. Phenotypic assays indicated that LINC01133 may promote proliferation and suppress cellular migration, and affect the cytoskeleton and morphology of the cells. Gene ontology analysis of differentially expressed genes indicated that cell proliferation and migration pathways were affected in line with the observed phenotype. We validated upregulation of p21 and downregulation of Cyclin A at the protein level, which together with the quantification of the DNA content using fluorescence-activated cell sorting (FACS) analysis indicated that the observed effects on cellular proliferation may be due to changes in cell cycle. Further, we found testis-specific protein kinase 1 (TESK1) kinase upregulation corresponding with phosphorylation and inactivation of actin severing protein Cofilin, which could explain changes in the cytoskeleton and cellular migration. These results indicate that endometriosis is associated with LINC01133 upregulation, which may affect pathogenesis via the cellular proliferation and migration pathways.     

Volatile Components in Dorsal Gland Secretions of the White-Lipped Peccary, Tayassu pecari, from Bolivia

Secretions from the dorsal gland of male and female free-ranging adult white-lipped peccaries (Tayassu pecari) from Bolivia were analyzed by gas chromatography–mass spectrometry. Fifty compounds were identified, some provisionally. Secretions of both sexes contain saturated and unsaturated C₅–C₁₈ carboxylic acids as well as isomers of the diterpene springene. The females' secretions uniquely possess farnesyl esters of C₈ and C₁₀ carboxylic acids, whereas the males' secretions uniquely showed two compounds provisionally identified as monounsaturated C₁₆ lactones. Saturated high-molecular-weight esters of C₁₀ carboxylic acids are more abundant in the females' secretions than in those of the males. The secretions of both sexes also contain monoalkanoate esters of methylhydroquinone as major components.     

Coupled T–H–M issues relating to radioactive waste repository design and performance

In this paper, coupled thermo-hydro-mechanical (THM) issues relating to nuclear waste repository design and performance are reviewed. Concise statements, that were developed from DECOVALEX discussions, on the current state-of-knowledge are presented. Section 1 describes the THM background and the interface with performance assessment (PA). The role of THM issues in the overall repository design context is amplified in Section 2, which includes a review of the processes in terms of repository excavation, operation and post-closure stages. It is important to understand the overall context, the detailed THM issues, the associated modelling and how these issues will be resolved in the wider framework. Also, because uncoupled and coupled numerical codes have been used for this subject, there is discussion in Section 3 on the nature of the codes and how the content of the codes can be audited. To what extent does a particular code capture the essence of the problem in hand? Consideration is also given to the associated question of code selection and the future of numerical codes. The state-of-knowledge statements are presented in Section 4 under 11 headings which follow the repository design sequence. The overview conclusion is that “A predictive THM capability is required to support repository design because precedent practice information is insufficient. Many aspects of THM processes and modelling are now well understood and there is a variety of numerical codes available to provide solutions for different host rock and repository conditions. However, modelling all the THM mechanisms in space and time is extremely complex and simplifications will have to be made — if only because it is not possible to obtain all the necessary detailed supporting information. Therefore, an important step is to clarify the THM modelling requirement within the PA context. This will help to indicate the complexity of THM modelling required and hence the models, mechanisms, type of computing, supporting data, laboratory and in situ testing, etc. required. An associated transparent and open audit trail should be developed.” We also include comments from reviewers and highlight four outstanding issues which are currently being studied in the DECOVALEX III programme.     

Acetyl-protected cytosine and guanine containing acrylics as supramolecular adhesives

Hydrogen bonding among nucleobase pairs serves as an efficient noncovalent interaction for designing supramolecular polymers with desired properties for pressure sensitive adhesives. Michael addition yielded acetyl-protected cytosine/guanine containing acrylic monomers with flexible spacers between the hydrogen bonding units and the acrylic backbone. Free radical polymerization of nucleobase-containing monomers afforded acetyl-protected cytosine/guanine homopolymers and random copolymers with n-butyl acrylate. Nucleobase incorporation significantly affected thermal, thermomechanical, rheological, morphological properties, and adhesive performance of polyacrylates. Guanine/cytosine-containing copolymers each exhibited a single glass transition (T_g) that increased with increasing nucleobase content. Self-association of acetyl cytosine and acetyl guanine units converted low T_g polyacrylates to physically crosslinked networks with mechanical integrity. Solution casting acetyl guanine-containing copolymers with 8 mol% or higher guanine content yielded free-standing films with microphase-separated morphologies. Acetyl cytosine-containing copolymers with 15 mol% or more cytosine formed free-standing films with less microphase-separation compared to the guanine copolymers. ¹H NMR titration experiments established a 1:1 binding stoichiometry between acetyl cytosine and acetyl guanine monomers in CDCl_3, similar to guanine-cytosine association. However, the acetyl protecting group hindered the formation of triple hydrogen bonding, resulting in double hydrogen bonding between acetyl cytosine and acetyl guanine with an intermediate binding strength comparable to their self-associations. Acetyl guanine-containing copolymers with 3 mol% acetyl guanine exhibited higher peel strength on stainless steel and higher extended service frequency range compared to cytosine-containing copolymers and various pressure sensitive adhesive controls.     

A diagnostic interview module for anabolic-androgenic steroid dependence: Preliminary evidence of reliability and validity.

The syndrome of anabolic-androgenic steroid (AAS) dependence, though well recognized, remains poorly studied. In this preliminary psychometric study, American and British investigators separately administered a structured diagnostic interview module, based on recently proposed criteria for AAS dependence, to 42 male AAS users in Middlesbrough, England. Another investigator, blinded to the diagnostic interview findings, assessed self-reported symptoms of “muscle-dysmorphia”; effects of AAS on various aspects of functioning; and maximum proportion of annual income spent on AAS. We also assessed demographic measures, history of other substance use, and performance on a hypothetical AAS-purchasing task. The interview module yielded very good interrater reliability (kappa = 0.76 and overall intraclass correlation = 0.79) and strong internal consistency (Cronbach's alpha = 0.77–0.87). Men diagnosed as AAS-dependent, when compared to nondependent men, reported significantly earlier onset of AAS use, longer duration and higher maximum doses of AAS used, more frequent use of other performance-enhancing drugs, and a somewhat larger maximum percentage of income spent on AAS. Dependent users also “bought” more AAS in the hypothetical purchase task, but rated significantly more negatively the effects of AAS on their mental health—findings all suggesting that the diagnosis of AAS dependence shows construct validity. As a group, AAS users showed high preoccupation with muscular appearance, but dependence per se was not significantly associated with this measure—suggesting that the diagnosis of AAS dependence shows some evidence of discriminant validity. Collectively, these findings suggest that AAS dependence may be diagnosed reliably, with preliminary evidence for construct and discriminant validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)