Hydrolysis of interfacial bonds in a metal/polymer electrical double layer

Effect of water on the electrical double layer structure at a metal/polymer interface is studied with the use of scanning vibrating capacitor and electrochemical impedance spectroscopy. In the initial stage, the Volta potential of the contact changes well reversibly and rapidly, being proportional to the water vapor pressure, following its diffusion in the polymer (V = A + B log (time)^1/2). Water dipoles at the metal/polymer interface orientate counter the field and compensate it. Drying of the contact restores the initial potential drop. In the first stage of exposure, water somewhat enhances the interfacial interaction, which manifests itself in increasing the potential drop, as well as the charge transfer resistance, and in decreasing the capacitance of the electrical double layer. As time passes, the interface hydrolyzes, its capacitance grows and the time of subsequently restoring the electrical double layer by drying increases. Kinetic dependences of the potential and capacitance, exhibit two segments, we ascribe to easily removable and strongly bonded water molecules solvating the interface, respectively. It is shown that metal-polymer interfacial bonds passivate the metal; however, the passivation can be broken down because of the hydrolysis and the interfacial moisture film formation.Translated from Zashchita Metallov, Vol. 41, No. 2, 2005, pp. 115–126.Original Russian Text Copyright © 2005 by Nazarov, Thierry.     

Incremental Deterministic Public-Key Encryption

Motivated by applications in large storage systems, we initiate the study of incremental deterministic public-key encryption. Deterministic public-key encryption, introduced by Bellare, Boldyreva, and O’Neill (CRYPTO ’07), provides an alternative to randomized public-key encryption in various scenarios where the latter exhibits inherent drawbacks. A deterministic encryption algorithm, however, cannot satisfy any meaningful notion of security for low-entropy plaintexts distributions, but Bellare et al. demonstrated that a strong notion of security can in fact be realized for relatively high-entropy plaintext distributions. In order to achieve a meaningful level of security, a deterministic encryption algorithm should be typically used for encrypting rather long plaintexts for ensuring a sufficient amount of entropy. This requirement may be at odds with efficiency constraints, such as communication complexity and computation complexity in the presence of small updates. Thus, a highly desirable property of deterministic encryption algorithms is incrementality: Small changes in the plaintext translate into small changes in the corresponding ciphertext. We present a framework for modeling the incrementality of deterministic public-key encryption. Our framework extends the study of the incrementality of cryptography primitives initiated by Bellare, Goldreich and Goldwasser (CRYPTO ’94). Within our framework, we propose two schemes, which we prove to enjoy an optimal tradeoff between their security and incrementality up to lower-order factors. Our first scheme is a generic method which can be based on any deterministic public-key encryption scheme, and, in particular, can be instantiated with any semantically secure (randomized) public-key encryption scheme in the random-oracle model. Our second scheme is based on the Decisional Diffie–Hellman assumption in the standard model. The approach underpinning our schemes is inspired by the fundamental “sample-then-extract” technique due to Nisan and Zuckerman (JCSS ’96) and refined by Vadhan (J. Cryptology ’04), and by the closely related notion of “locally computable extractors” due to Vadhan. Most notably, whereas Vadhan used such extractors to construct private-key encryption schemes in the bounded-storage model, we show that techniques along these lines can also be used to construct incremental public-key encryption schemes.     

Influence of the Processing Mode of Nonwoven Needle-Punched Materials on Air Filtration

Fibre Chemistry - The influence of the processing rate of nonwoven needle-punched fabrics made of polyethylene terephthalate and bicomponent fibres of different surface density on air filtration...     

The Effect of Morphological Surface Inhomogeneities on the Mycological Resistance of Polymer Films

Protection of Metals and Physical Chemistry of Surfaces - Polymer materials, such as polyethylene, polypropylene, polyvinyl chloride, polybutadiene, and polyethylene terephthalate, are widely used...     

Anisotropic thermal conductivity of polypropylene composites filled with carbon fibers and multiwall carbon nanotubes

Polypropylene‐based composites filled with carbon fibers and multiwall carbon nanotubes were produced by coagulation precipitation technique. Composite articles were produced by conventional injection molding technique. It was shown that the addition of carbon nanotubes (10% of total amount of carbon fibers) results in significantly increased anisotropic thermal conductivity of the composite due to formation of thermal conductive bridges between carbon fibers, which are oriented during molding. The addition of CNTs has a significant effect with more than a 50–70% increase of both the axial and transverse thermal conductivity of the composite. Produced composites were used for injection molding of polymeric radiators for LED lamps, showing sufficient heat dissipation efficiency allowing using them for industrial application in the field. POLYM. COMPOS., 36:1951–1957, 2015. © 2014 Society of Plastics Engineer     

Millimeter- and submillimeter-wave characterization of various fabrics

Transmission measurements of 14 fabrics are presented in the millimeter-wave and submillimeter-wave electromagnetic regions from 130 GHz to 1.2 THz. Three independent sources and experimental set-ups were used to obtain accurate results over a wide spectral range. Reflectivity, a useful parameter for imaging applications, was also measured for a subset of samples in the submillimeter-wave regime along with polarization sensitivity of the transmitted beam and transmission through doubled layers. All of the measurements were performed in free space. Details of these experimental set-ups along with their respective challenges are presented.     

A glucose derivative as natural alternative to the cyclohexane‐1,2‐diamine ligand in the anticancer drug oxaliplatin?

Having oxaliplatin as archetype, several platinum complexes with a carbohydrate moiety resembling the cyclohexane-1,2-diamine ligand of oxaliplatin have been prepared. As leaving groups, the anionic ligands iodide, oxalate, and malonate were utilized, and for comparison purposes the chloro complex was employed. All compounds were characterized by elemental analysis, nuclear magnetic resonance spectroscopy, and electrospray mass spectrometry. The crystal structure of (SP-4-3)-diiodo(2,3-diamino-2,3-dideoxy-D-glucose-kappa(2)N,N')platinum(II) was determined by X-ray diffraction. The affinity toward dGMP was assayed by capillary electrophoresis, revealing that the chloro complex shows the highest reactivity, followed by the iodo complex. In contrast, the binding kinetics of the dicarboxylato complexes are slower, with the malonato complex being the least reactive. Reactivity to dGMP in the cell-free system correlates with cytotoxicity in two of four human cancer cell lines as determined by means of the MTT assay. In three of the four cell lines, the chloro and the malonato complex are the most and the least active of the carbohydrate-Pt complexes, respectively, with IC(50) values differing only by factors of up to 3.2. Cytotoxicity of the chloro complex is one to two orders of magnitude lower than that of oxaliplatin, but still comparable to that of carboplatin in two of the four cell lines.     

Hearing what you cannot see and visualizing what you hear: interpreting quartz crystal microbalance data from solvated interfaces

Over the last 2 decades, the quartz crystal microbalance (QCM or QCM-D) has emerged as a versatile tool for investigating soft and solvated interfaces between solid surfaces and bulk liquids because it can provide a wealth of information about key structural and functional parameters of these interfaces. In this Feature, we offer QCM users a set of guidelines for interpretation and quantitative analysis of QCM data based on a synthesis of well-established concepts rooted in rheological research of the last century and of new results obtained in the last several years.     

Surface-enhanced raman scattering (SERS) detection of low concentrations of tryptophan amino acid in silver colloid

The surface-enhanced Raman scattering (SERS) spectrum of L-tryptophan has been studied in the concentration range 1.4 × 10(-8) to 5 × 10(-4) M. A borohydride-reduced silver colloid was employed as the nanoparticle enhancing agent and different electrolytes have been tested for activation of the colloid. The optimum conditions have been determined for achieving high sensitivity of detection. The experimental procedure developed, which includes the use of a composite electrolyte (a mixture of NaHCO(3) and NaCl) for colloid activation, results in very high enhancement of the Raman signal (up to 10(8)). This gives the possibility of studying SERS spectra of L-tryptophan at concentrations as low as 10(-8) M, which is several orders of magnitude lower than previously reported in the literature. The observed SERS spectra were very reproducible and were detectable 2 minutes after mixing, reaching maximum strength approximately 15 minutes after mixing. The spectral characteristics were stable over the entire period of observation. We have found that SERS spectra of tryptophan in silver colloid differ in several features at low (below ～10(-5) M) and at high (above ～10(-4) M) concentrations. The most important difference is the absence of the peak near 1000 cm(-1) at low concentrations, which is usually assigned to the indole ring breathing mode. The observed spectra allow us to suggest that at low concentrations Trp molecules bind to the surface through the indole ring, which remains flat on the surface. This is in contrast to the previously reported observation of SERS spectra from Trp performed at concentration levels above 10(-5) M.