Membrane-active bacteriocins to control Salmonella in foods: Are they the definite hurdle?

According to recent surveys salmonellosis is the main disease caused by foodborne microorganisms in many countries. Although traditional methods to control bacterial contamination in food are effective in controlling Salmonella, a major problem arises with fresh and organic food demanded by the market with little preparation and no chemical additives. Besides the development of new technologies that combine soft physical and chemical treatments in a way that causes minimal changes in food properties, antimicrobial peptides derived from natural sources are presented as an interesting alternative to chemical preservatives. There are many bacteriocins active against Salmonella and they could be used in the food industry alone or in combination with other hurdles to increase the anti-Salmonella effect in the so-called hurdle technology. However, further studies are necessary to demonstrate the safety of new bacteriocins and to improve their activity in different environmental conditions encountered during food processing. Moreover, nisin and pediocin PA-1 already approved as food preservatives by various government agencies, can be used along with other hurdles to control the pathogen in foods. In this paper the use of bacteriocins as hurdles for controlling Salmonella in the future is discussed and analyzed.     

Efficient Approach to Compute Generalized Interdependent Effects between Infrastructure Systems

Most studies on infrastructure interdependencies only explore a subset of the possible damage states in which they operate. Typically, interdependence effects (IE) are measured in terms of common failure fractions (f) of components across systems. In this paper, an expanded damage space is explored where infrastructure systems can simultaneously experience different failure fractions f. This augmented space is then mapped onto a functionality space where IEs are evaluated as a function of the efficiencies of constitutive systems: a desirable feature because efficiency is typically measured and recorded in practice whereas f is not. These new IEs conditioned on efficiency levels are termed generalized interdependent effects (GIE), which can be predicted or detected in a computationally efficient fashion. Prediction is a function of initial efficiencies before damage propagation and can be used in prefailure analyses, whereas detection is a function of final joint efficiencies for postfailure analyses. To illustrate the quantification of the nonnegative GIE metric, this study uses artificial power (p) and gas (g) networks with flow traversal capabilities. Results show that the maximum predicted or detected GIE of power on gas and gas on power among all efficiencies are GIEp→gmax? = 1.54 and GIEg→pmax? = 0.19, respectively, highlighting the relative inadequacy of the gas system to function independently (high GIE) and vice versa. The proposed practical metric is expected to provide useful information to infrastructure decision makers on strategies to design interdependent topology and handle interdependencies when operating at different regimes.     

Cooperative-feedback control

In this work a control structure capable of handling controllability problems, which emerge from the presence of constraints, and improve the performance of the system by coordinating the use of several manipulated variables is introduced. In this scheme, the primary manipulated variable is used to handle the transient response while the auxiliary manipulated variable is used to keep the primary manipulated variable away from saturation. These two manipulated variables are coordinated through a user-defined non-linear function, which decides when and how the control structure changes. Its parameters determine the interaction between both inputs and the steady state value of each manipulated variable. The effectiveness of the proposed scheme is illustrated in two simulation examples.     

Effect of rotary instrument associated with different irrigation techniques on removing calcium hydroxide dressing

Calcium hydroxide [Ca(OH)₂] residues in root canals may compromise sealing of filling and endodontic treatment success. The aim of this study was to compare the efficacy of using rotary instrument associated with EndoActivator, EndoVac, passive ultrasonic irrigation (PUI), and conventional needle irrigation (CNI), in Ca(OH)₂ removal from root canal, by means of scanning electron microscopy (SEM) images. Sixty‐six human canines were prepared with the Protaper system up to F5 and filled with Ca(OH)₂. After 7 days, Ca(OH)₂ was removed with rotary instrument F5 associated with the irrigation techniques used in each group (n = 15): GI (CNI), GII (EndoVac), GIII (EndoActivator) and GIV (PUI). In all groups 15 mL of 2.5% NaOCl and 3 mL of 17% EDTA were used for Ca(OH)₂ removal. The Ca(OH)₂ residues was evaluated by SEM in the middle and apical third using a system of scores. The results were analyzed by the Kruskal‐Wallis and Dunn tests (α = 0.05). None of the techniques completely removed the Ca(OH)₂ from root canals. There was no difference between EndoActivator, EndoVac and PUI (P > 0.05), but the three techniques removed more Ca(OH)₂ than the CNI (P < 0,05), in the middle and apical thirds of the root canal. It was concluded that the rotary instrument combined with EndoActivator, EndoVac, and PUI was shown to be more efficient than the rotary instrument combined with the CNI in removing Ca(OH)₂ from the root canal. Microsc. Res. Tech. 77:642–646, 2014. © 2014 Wiley Periodicals, Inc.     

Process adapted structure optimization of deep hole drilling tools

In order to machine boreholes having a high length-to-diameter ratio, deep hole drilling methods are applied. Especially when drilling ductile materials, the removal of cooling lubricant and chips can be hindered by long chips which block the inside of the chip mouth. In order to increase the volume flow rate of the cooling lubricant and chips, the chip mouth cross-section of a commercially available state-of-the-art BTA (Boring and Trepanning Association) boring tool was analyzed. Structure topology optimization was applied to reduce the drill head material without the drill head losing its stiffness to maximize the chip mouth cross-section. Finally, new drill head design was developed and verified through experimental investigations.     

Preparation of TNT,RDX and Ammonium Nitrate Standards on Gold-on-Silicon Surfaces by Thermal Inkjet Technology

This research examines the surface contamination properties, trace sample preparation methodologies, detection systems response and generation of explosive contamination standards for trace detection systems. Homogeneous and reproducible sample preparation is relevant for trace detection of chemical threats, such as warfare agents, highly energetic materials (HEM) and toxic industrial chemicals. The objective of this research was to develop a technology capable of producing samples and standards of HEM with controlled size and distribution on a substrate to generate specimens that would reproduce real contamination conditions. The research activities included (1) a study of the properties of particles generated by two deposition techniques: sample smearing deposition and inkjet deposition, on gold-coated silicon, glass and stainless steel substrates; (2) characterization of composition, distribution and adhesion characteristics of deposits; (3) evaluation of accuracy and reproducibility for depositing neat highly energetic materials such as TNT, RDX and ammonium nitrate; (4) a study of HEM-surface interactions using FTIR-RAIRS; and (5) establishment of protocols for validation of surface concentration using destructive methods such as HPLC.     

Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were 35 m for dimethyl methylphosphonate (DMMP) detection and 60, 90 and 140 m for cyclohexane detection. The prototype systems consisted of a Raman spectrometer equipped with a CCD detector (for CW measurements) and an I-CCD camera with time-gated electronics (for pulsed laser measurements), a reflecting telescope, a fiber optic assembly, a single-line CW laser source (514.5, 488.0, 351.1 and 363.8 nm) and a frequency-doubled single frequency Nd:YAG 532 nm laser (5 ns pulses at 10 Hz). The telescope was coupled to the spectrograph using an optical fiber, and filters were used to reject laser radiation and Rayleigh scattering. Two quartz convex lenses were used to collimate the light from the telescope from which the telescope-focusing eyepiece was removed, and direct it to the fiber optic assembly. To test the standoff sensing system, the Raman Telescope was used in the detection of liquid TIC: benzene, chlorobenzene, toluene, carbon tetrachloride, cyclohexane and carbon disulfide. Other compounds studied were CWAS: dimethylmethyl phosphonate, 2-chloroethyl ethyl sulfide and 2-(butylamino)-ethanethiol. Relative Raman scattering cross sections of liquid CWAS were measured using single-line sources at 532.0, 488.0, 363.8 and 351.1 nm. Samples were placed in glass and quartz vials at the standoff distances from the telescope for the Remote Raman measurements. The mass of DMMP present in water solutions was also quantified as part of the system performance tests.     

Machinability aspects concerning micro-turning of PA66-GF30-reinforced polyamide

This paper aims to study the behavior of machining forces and machined surface finish when micro-turning PA66-GF30-reinforced polyamide with various tool materials under distinct cutting conditions. The performance of polycrystalline diamond (PCD), CVD diamond coated carbide and plain cemented carbide tools (K15-KF and K15) were investigated in addition to the influence of feed rate on cutting forces, surface roughness and chip formation. The results indicated that the radial force was the highest force component because of the reduction in the effective cutting edge angle. Moreover, the cutting force increased almost linearly with feed, whereas the feed and radial forces remained unaltered. The cutting tools possessing lower edge radius promoted lower surface finish and turning forces, i.e., the best results were provided by the PCD tool, followed by the uncoated carbide inserts and finally by the CVD diamond-coated carbide tool.     

Identification and quantification of β-caryophyllene in copaiba oil using Raman spectroscopy

Copaiba oleoresin presents several compounds with known biologic activity and physiologic effects, including analgesic and insecticide properties. Among them are the terpenoids (mainly diterpenes and sesquiterpenes) with β-caryophyllene, the main representative of the terpenoids and considered to be a chemical marker. This study employed Raman spectroscopy and principal component analysis (PCA) techniques to identify and quantify the β-caryophyllene marker in copaiba oil samples purchased from popular markets in Brazil. A dispersive Raman spectrometer (830?nm, 250?mW, 2?cm^?1 spectral resolution) was used. Results showed the identification of the main Raman peaks from the β-caryophyllene in copaiba oil samples (main peaks at 507, 771, 1442, 1638, and 1673?cm^?1). The loading vector 2 (PC2) extracted the spectral information from β-caryophyllene in the samples and the eigenvalue 2 (score 2) allowed the estimation of the concentration of this marker in commercial samples, with the concentrations from 15 to 34%. Raman spectroscopy combined with PCA may be considered to be a potential analytical tool for the quality control of Copaifera oil samples by quantifying β-caryophyllene using its unique spectral information.     

The Cyclic Cystine Ladder of Theta‐Defensins as a Stable,Bifunctional Scaffold: A Proof‐of‐Concept Study Using the Integrin‐Binding RGD Motif.

Peptides have the specificity and size required to target the protein–protein interactions involved in many diseases. Some cyclic peptides have been utilised as scaffolds for peptide drugs because of their stability; however, other cyclic peptide scaffolds remain to be explored. θ‐Defensins are cyclic peptides from mammals; they are characterised by a cyclic cystine ladder motif and have low haemolytic and cytotoxic activity. Here we demonstrate the potential of the cyclic cystine ladder as a scaffold for peptide drug design by introducing the integrin‐binding Arg‐Gly‐Asp (RGD) motif into the θ‐defensin RTD‐1. The most active analogue had an IC₅₀ of 18 nM for the α_vβ₃ integrin as well as high serum stability, thus demonstrating that a desired bioactivity can be imparted to the cyclic cystine ladder. This study highlights how θ‐defensins can provide a stable and conformationally restrained scaffold for bioactive epitopes in a β‐strand or turn conformation. Furthermore, the symmetry of the cyclic cystine ladder presents the opportunity to design peptides with dual bioactive epitopes to increase activity and specificity.