Oxidation of γ‐irradiated microbial cellulose results in bioresorbable,highly conformable biomaterial

Conformability to tissues and adequate mechanical strength are clinically useful properties of resorbable biomaterials used in soft tissue repair. Microbially derived cellulose is attractive as a high strength, highly conformable, and biocompatible material for tissue repair, but is not naturally resorbable. Here we show that controlled oxidation of microbial cellulose sheets that have been pre‐irradiated with γ‐radiation results in a resorbable and fully conformable membrane that can be rapidly rehydrated in aqueous fluids. In vitro studies showed that degradation of the resorbable membranes occurs in two major phases: (1) initial rapid degradation of about 70–80% of the entire sample followed by (2) slower degradation of an additional 5–10% which eventually levels off leaving a small amount of nonresorbable material. In vivo, prototype materials showed marked degradation at all time points, with the most rapid degradation occurring in the first 2–4 weeks. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39995.     

Monovinyl Sulfone β‐Cyclodextrin. A Flexible Drug Carrier System

Cyclodextrins have been conjugated to target various receptors and have also been functionalized with carbohydrates for targeting specific organs. However, this approach is based on a rigid design that implies the ad hoc synthesis of each cyclodextrin‐targeting agent conjugate. We hypothesized that: 1) a modular design that decouples the carrier function from the targeting function leads to a flexible system, 2) combining the reactivity of the vinyl sulfone group toward biomolecules that act as targeting agents with the ability of cyclodextrin to form complexes with a wide range of drugs may yield a versatile system that allows the targeting of different organs with different drugs, and 3) the higher reactivity of histidine residues toward the vinyl sulfone group can be exploited to couple the cyclodextrin to the targeting system with a degree of regioselectivity. As a proof of concept, we synthesized a monovinyl sulfone β‐cyclodextrin (module responsible for the payload), which, after coupling to recombinant antibody fragments raised against Trypanosoma brucei (module responsible for targeting) and loading with nitrofurazone (module responsible for therapeutic action) resulted in an effective delivery system that targets the surface of the parasites and shows trypanocidal activity.     

Predicting author h-index using characteristics of the co-author network

The objective of this work was to test the relationship between characteristics of an author’s network of coauthors to identify which enhance the h-index. We randomly selected a sample of 238 authors from the Web of Science, calculated their h-index as well as the h-index of all co-authors from their h-index articles, and calculated an adjacency matrix where the relation between co-authors is the number of articles they published together. Our model was highly predictive of the variability in the h-index (R ² = 0.69). Most of the variance was explained by number of co-authors. Other significant variables were those associated with highly productive co-authors. Contrary to our hypothesis, network structure as measured by components was not predictive. This analysis suggests that the highest h-index will be achieved by working with many co-authors, at least some with high h-indexes themselves. Little improvement in h-index is to be gained by structuring a co-author network to maintain separate research communities.     

Study of the enantiomeric composition of chiral constituents in edible oils by simultaneous distillation-extraction. Detection of adulterated olive oils

A method is proposed for detecting adulterations of olive oil with hazelnut oil at percentages as low as 5%. The method is based on the identification of R- and S-enantiomers of E-5-methylhept-2-en-4-one (filbertone) and involves the use of simultaneous distillation-solvent extraction in the sample preparation step and subsequent gas chromatographic analysis with a chiral stationary phase. Relative standard deviation values obtained from three replicates of adulterated mixtures of olive oil and hazelnut oil (95:5) were less than 9% for both R-and S-filbertone.     

Optimal constrained adjustments for quality control

This paper considers the optimal adjustment of a production process under fixed adjustment and quadratic off-target quality costs, when the magnitude of the adjustment is constrained to lie within certain upper bound. The process model is that of the Box and Jenkins' 'machine tool' problem. Formulas for both end of run and long-run adjustment limits are presented. It is shown that unless the adjustment is severely constrained, in most cases the unconstrained limits are nearly as good as the considered optimal limits. Cases when the constrained solution is more economical are discussed. This includes applications in semiconductor manufacturing. An example from a chemical-mechanical wafer polishing process illustrates the use of the constrained optimal adjustment limits.     

Setup adjustment for discrete-part manufacturing processes with asymmetric cost functions

This paper presents a feedback adjustment rule for discrete-part manufacturing processes that experience errors at the setup operation which are not directly observable due to part-to-part variability and measurement error. In contrast to previous work on setup adjustment, the off-target cost function of the process is not symmetric around its target. Two asymmetric cost functions—constant and quadratic functions—are considered in this paper. By introducing a bias term in the feedback adjustment rule, the process quality characteristic converges to the optimal steady-state target from the lower cost side of the cost function. This minimizes the off-target loss incurred during the transient phase of adjustment. A machining application is used to illustrate the proposed adjustment procedure and to demonstrate the savings generated by the proposed feedback adjustment rule compared to an adjustment rule due to Grubbs and to an integral controller. It is shown that the advantage of the proposed rule is significant when the cost of the items is high, items are produced in small lot sizes and the asymmetry of the cost function is large.     

Visualizing and exploring profiles with calling context ring charts

Calling context profiling is an important technique for analyzing the performance of object‐oriented software with complex inter‐procedural control flow. The Calling Context Tree (CCT) is a common data structure that stores dynamic metrics, such as CPU time, separately for each calling context. As CCTs may comprise millions of nodes, there is a need for a condensed visualization that eases the localization of performance bottlenecks. In this article, we discuss Calling Context Ring Charts (CCRCs), a compact visualization for CCTs, where callee methods are represented in ring segments surrounding the caller's ring segment. In order to reveal hot methods, their callers, and callees, the ring segments can be sized according to a chosen dynamic metric. We describe two case studies where CCRCs help us to detect and fix performance problems in applications. A performance evaluation also confirms that our implementation can efficiently handle large CCTs. Copyright © 2010 John Wiley & Sons, Ltd.     

Thomas Young on fluid mechanics

Thomas Young was a prolific scholar who made many contributions to science, medicine and the humanities. Here, his writings on fluid mechanics are reviewed. The best known of these are on tides and on surface tension; but he did much else besides. These include his wide-ranging lectures to the Royal Institution, his rather eccentric reworking of Book 1 of Laplace’s Mécanique céleste, and papers on pneumatics and hydraulics. Among the latter are perhaps the first observation of transition to turbulence in jets of air; an empirical formula for the resistance of hydraulic flow in pipes, suggested by his own experiments with thin tubes; and probably the first, but incomplete, attempt at a theory of the hydraulic jump or bore. All of this work is characterised by sound physical insight but mathematical limitations.     

A new Price’s estimate on the size of scientific specialties based on scientific community structure

Price argued that the average scientific specialty consists of about 100 scientists, publishing an average 100 articles each during their career. Wray recently attempted to revise the number of scientists in a specialty based on the information that the average scientist publishes only 3.5 papers during their career. However, his final estimate, between 250 and 600 scientists, does not support Price’s idea that a specialty fills about 10,000 articles, unless the ad hoc assumption is made that nearly 80 % of articles circulating in a field are from other fields. This article shows that by distinguishing between graduate students, who spend only a couple of years in a specialty, and professors, who spend their entire career in a field, the ad hoc assumption becomes unnecessary, and Wray’s number of 600 scientists turns out to be a remarkable intuitive insight that is consistent with Price’s 10,000 articles. A number of 520 scientists, or somewhat larger, is suggested for Price’s estimate.     

Fibrous membranes of cellulose acetate and poly(vinyl pyrrolidone) by electrospinning method: Preparation and characterization

Fibrous membranes of cellulose acetate (CA), poly(vinyl pyrrolidone) (PVP) and composite membranes of these polymers, were obtained by the electrospinning method. Using systematic method, the optimal conditions for preparation of fibrous membranes were found. Both CA and PVP a concentration of 8% weight was found. The CA was dissolved in a acetone:water solution, volume ratio 80 : 20 and the PVP is dissolved in ethanol:water solution, ratio volume 85 : 15. The flow rate for both polymers was 1.5 mL h^?1. The same applied voltage value and the distance between the needle and collection plate were for polymer both, 15 kV and 15 cm respectively. The morphology of fibrous membranes and composite membranes were evaluated by scanning electron microscopy (SEM). The CA fibers showed ribon morphology, while the PVP fibers were cilindric, in both cases with diameters in the micrometer range. Thermogravimetric analysis showed that CA had a complete degradation to 445°C, while the fibrous membranes PVP required a value of temperature for degradation of up to 571°C. Fibrous composite membrane PVP/CA/PVP shows a higher value of strain at break (%), and a lower value of tensile strength (MPa) compared to CA/PVP/CA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010