Novel biodegradable amino acid containing anhydride oligomers for orthopedic applications

Novel synthetic biodegradable methacrylated anhydride oligomers (MAOs) based on methacrylated alaninyl maleamic acid (MAMA) and methacrylated aminocaproyl maleamic acid (MACMA) were synthesized and characterized. Injectable and in situ crosslinkable polymer networks were formulated by the copolymerization of MAOs with triethylene glycol dimethacrylate (TEGDMA). Furthermore, composites composed of MAOs, TEGDMA, and β‐tricalcium phosphate were prepared. The networks and composites were initiated by photopolymerization and redox polymerization, respectively. The initial compressive strength (CS) and diametral tensile strength (DTS) of these materials were determined and used to evaluate the effects of the MAO/TEGDMA ratios on the degradation behavior of the materials. The MAMA‐based composites had initial DTS values of 5.7–17.1 MPa and CS values of 30.7–114.2 MPa. The MACMA‐based composites had initial DTS values of 2.8–20.8 MPa and CS values of 19.1–119.5 MPa. During the course of degradation, the neat polymer resins lost 97 and 87% of their initial CS values after 6 months with 50/50 MAMA/TEGDMA and MACMA/TEGDMA ratios, respectively. The composite with a 25/75 MACMA/TEGDMA ratio showed a significant increase in CS after an initial decrease for 7 days and then lost 57% of its initial CS value after 3 months. The composite composed of 100% methacrylated anhydride oligomer (MAOs) showed complete degradation after 21 days. The degrees of conversion of the neat resins were 60–77%. Both the neat resins and the composites had low polymerization shrinkage ranging from 3.8 to 5.6%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1979–1984, 2005     

Discrete Tagaki–Sugeno models for control: Where are we?

This work deals with relaxed conditions for stability and stabilization of discrete-time Takagi–Sugeno (TS) models. It recalls classical results found in the literature which use quadratic Lyapunov functions leading to very conservative conditions, and various extensions based on piecewise and non-quadratic Lyapunov functions. Afterwards, a new and powerful way to enhance the previous results is depicted. The basic idea is that waiting long enough a stable model will converge towards its equilibrium and, therefore, the Lyapunov functions under consideration are not necessarily decreasing at every sample, but are allowed to decrease every k samples. Whatever it is k >1, the results are proved to include the standard one-sample case. The potential of this approach is shown through several examples in the paper.     

先进栅叠层的在线光谱分析法

量测平台的复杂性和光学原理上的局限性制约着测量系统的应用，直到真空紫外光谱反射仪的出现，这种状况才得到改变。     

Copper‐Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl‐N‐methylimidazole Michael Acceptors: Scope,Limitations and Iterative Reactions

An efficient copper‐catalyzed enantioselective conjugate addition of dimethylzinc to unsaturated 2‐acyl‐N‐methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl‐NHC ligand. The reactions proceed with excellent regioselectivity (1,4 vs. 1,6 and 1,8) in extended conjugated systems to afford the 1,4‐adducts in high enantioselectivities. This regioselectivity could be ascertained by DFT studies highlighting the crucial role of the imidazole ring. Thanks to the development of efficient protocols to regenerate the unsaturated 2‐acyl‐N‐methylimidazole moiety, an iterative process has been developed ultimately leading to 3,5,7 all‐syn or anti‐anti polydeoxypropionate stereodiads.

     

Evaluation of harassment of migrating double-crested cormorants to limit depredation on selected sport fisheries in Michigan

Diverse management techniques have been used to mitigate conflicts between humans and double-crested cormorants (Phalacrocorax auritus) including harassment methods supplemented by lethal take. In this study we evaluated impacts of programs to harass spring migrating cormorants on the walleye (Sander vitreus) fishery in Brevoort Lake and the yellow perch (Perca flavescens) and walleye fisheries at Drummond Island. Cormorant foraging declined significantly (p < 0.05) at both locations subsequent to initiation of harassment programs. Overall harassment deterred 90% of cormorant foraging attempts while taking less than 6% lethally on average at each site. Yellow perch were a predominate prey item in number and biomass at both locations. Walleye made up a small proportion of the diet at both locations. However, both walleye and yellow perch abundance increased significantly (p < 0.05) at Drummond Island. Walleye abundance at age 3 increased to record levels in 2008 following 3 years of cormorant management at Brevoort Lake. The estimated cormorant consumption of age-1 walleye in the absence of management at Brevoort Lake during 2005 would account for 55% of the record 2006 age-1 walleye population. These results support the hypothesis that cormorant predation on spawning aggregations of sportfish was a significant mortality factor and cormorant management reduced sportfish mortality and increased abundance at both locations. Continuation of harassment programs and fishery assessments will determine whether improvement of targeted sport fisheries through control of spring migrating cormorants is sustainable.     

Synergistic inhibition of Listeria monocytogenes in vitro through the combination of octanoic acid and acidic calcium sulfate

It has been hypothesized that inhibition of foodborne pathogens can be enhanced by using antimicrobials in combination. A broth dilution assay was devised to determine whether inhibition of Listeria monocytogenes exposed to the combination of the fatty acid octanoic acid (OCT) and the organic acid-containing antimicrobial acidic calcium sulfate (ACS) was enhanced compared with the inhibition of the pathogen exposed to either antimicrobial applied singly. MICs for OCT and ACS were 25.00 μg/g and 1.56 ml/liter, respectively, for all strains of the pathogen tested. Fractional inhibitory concentrations (FICs) from the combination exposures were calculated for use in characterizing the antimicrobial interaction as antagonistic, additive indifferent, or synergistic with respect to L. monocytogenes inhibition. Combining OCT and ACS resulted in observed synergistic inhibition of L. monocytogenes; isobolograms for all strains curved toward the origin, and FIC indices (FIC(I)s) were <1.0. Future investigations of the antimicrobial combination should focus on determining the mechanism of action of combined antimicrobials and the levels of antimicrobials required for pathogen inhibition on the surfaces of ready-to-eat meats.     

A statistical investigation of wind characteristics and wind energy potential based on the Weibull and Rayleigh models in Rwanda

A wind energy system converts the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical uses and transform the economy of rural areas where access to water and electricity is very restricted and industry is almost nonexistent in most of the developing countries like Rwanda. Assessing wind power potential for a location is an imperative requirement before making a decision for the installation of windmills or a wind electric generator and evaluating plans for relating projects. The aim of the present study was to evaluate the potential of wind resource in Rwanda and to constitute a database for the users of the wind power. A time series of hourly daily measured wind speed and wind direction for the period between 1974 and 1993 on five main Rwandan meteorological stations was provided by the National Meteorology Department. Statistical methods applying Weibull and Rayleigh distribution were presented to evaluate the wind speed characteristics and the wind power potential at a height of 10 m above ground level using hourly monthly average data. Those characteristics were extrapolated for higher levels in altitude. The results give a global picture of the distribution of the wind potential in different locations of Rwanda.     

Reduced autonomy workspace (RAW)—an interaction design approach for human-automation cooperation

Cognition, Technology & Work - Lack of support for handling a reduction of autonomy in a highly autonomous automation may lead to a stressful situation for a human when forced to take over. We...     

Linguistic frequent pattern mining using a compressed structure

Traditional association-rule mining (ARM) considers only the frequency of items in a binary database, which provides insufficient knowledge for making efficient decisions and strategies. The mining of useful information from quantitative databases is not a trivial task compared to conventional algorithms in ARM. Fuzzy-set theory was invented to represent a more valuable form of knowledge for human reasoning, which can also be applied and utilized for quantitative databases. Many approaches have adopted fuzzy-set theory to transform the quantitative value into linguistic terms with its corresponding degree based on defined membership functions for the discovery of FFIs, also known as fuzzy frequent itemsets. Only linguistic terms with maximal scalar cardinality are considered in traditional fuzzy frequent itemset mining, but the uncertainty factor is not involved in past approaches. In this paper, an efficient fuzzy mining (EFM) algorithm is presented to quickly discover multiple FFIs from quantitative databases under type-2 fuzzy-set theory. A compressed fuzzy-list (CFL)-structure is developed to maintain complete information for rule generation. Two pruning techniques are developed for reducing the search space and speeding up the mining process. Several experiments are carried out to verify the efficiency and effectiveness of the designed approach in terms of runtime, the number of examined nodes, memory usage, and scalability under different minimum support thresholds and different linguistic terms used in the membership functions.

     

Anchoring hydroxyl intermediate on NiCo(OOH)x nanosheets to enable highly efficient electrooxidation of benzyl alcohols

Selective oxidation of alcohols to the carboxylic acid plays an important role in the production of valuable chemicals. Herein, NiCo hydroxide (NiCo(OOH)_x) nanosheets with a thickness of ~4 nm were controllably fabricated in a facile way efficient for the electrooxidation of benzyl alcohol (BAL) to benzoic acid (BAD). Mechanistic studies confirmed the hydroxyl active intermediate ( OH*) generated on the surface of NiCo(OOH)_x nanosheets through operando electrochemical impedance spectroscopy and the electron paramagnetic resonance spectroscopy analysis during the electrooxidation process. Importantly, we discovered that the  OH* was crucial to boost the selective oxidation of BAL by attacking the hydroxyl end group to achieve carboxylic acid. The early onset potential of 1.16 V_RHE in the presence of BAL was below 1.23 V_RHE for oxygen evolution reaction. The rotating ring-disk electrode further revealed that the electrocatalytic BAL oxidation reaction occurred earlier in the oxygen evolution reaction. In 150 mM BAL, NiCo(OOH)_x nanosheets generated a high BAD selectivity of >99% and full conversion of BAL in 3 h. The experimental and theoretical calculation revealed that the dominant pathway of BAL oxidation was the interaction between nucleophilic BAL with  OH* to form BAL-OH* directly by dehydrogenates, thereby producing BAD with high efficiency. This research sheds mechanism insights on the electrocatalytic alcohols oxidation reaction.