Evgeny Shulzinger

Physical mechanisms of interaction of cold plasma with polymer surfaces

Physical mechanisms of the interaction of cold plasmas with organic surfaces are discussed. Trapping of plasma ions by the CH2 groups of polymer surfaces resulting in their electrical charging is treated. Polyethylene surfaces were exposed to the cold radiofrequency air plasma for different intervals of time. The change in the wettability of these surfaces was registered. The experimentally established characteristic time scales of the interaction of cold plasma with polymer surfaces are inversely proportional to the concentration of ions. The phenomenological kinetic model of the electrical charging of polymer surfaces by plasmas is introduced and analyzed.

Fiberoptic infrared spectroscopy: a novel tool for the analysis of urine and urinary salts in situ and in real time.

OBJECTIVES To use infrared fiberoptic spectroscopy for the analysis of urinary salts in real time and with no sample processing; and to assess the practical role of this method for the quantitative measurement of the composition of urine and for the diagnosis of urolithiasis in patients. METHODS Urine samples were obtained from two groups of patients: 24 patients with stone formation after shock wave lithotripsy and 24 normal subjects of similar age. Infrared absorption measurements were performed in real time, using infrared transmitting silver halide fibers. The absorption data were compared with the infrared absorption spectra of aqueous solutions prepared in our laboratory, with known concentrations of known urinary salts. The results were used for the study of the chemical composition of these salts in the urine samples and for a quantitative analysis of the concentration of the salts. RESULTS We determined the composition of the stones in 20 of the 24 patients on the basis of the characteristic absorption peaks for the oxalates, carbonates, urates, and phosphates observed in their urinary samples. Using the method mentioned above, we found the concentration of different salts in urine with an average error of 20%. CONCLUSIONS Fiberoptic infrared spectroscopy could be used as a new diagnostic tool for detecting different urinary salts in urine, finding their chemical composition, and determining their concentrations, without any sample preparation.

Progress in low voltage reversible electrowetting with lubricated polymer honeycomb substrates

Low-voltage electrowetting on liquid infused films realized with lubricated honeycomb polymer surfaces is reported. Introduction of ethylene carbonate into the polymer (polycarbonate) matrix allowed an increase in the sensitivity of the scheme. A theoretical analysis of the thermodynamics of the electrowetting on a liquid infused film is reported. Fitting of experimental data to theoretical curves allowed an estimation of the specific capacity of the double layer. An analysis of the viscous dissipation taking place under the proposed electrowetting scheme is presented.

Self-assembled levitating clusters of water droplets: pattern-formation and stability

Water forms ordered hexagonally symmetric structures (snow crystals) in its solid state, however not as liquid. Typically, mists and clouds are composed of randomly moving small droplets lacking any ordered structure. Self-organized hexagonally patterned microdroplet clusters over locally heated water surfaces have been recently observed. However, many aspects of the phenomenon are far from being well understood including what determines droplets size, arrangement, and the distance between them. Here we show that the Voronoi entropy of the cluster tends to decrease indicating to their self-organization, while coupling of thermal effects and mechanical forces controls the stability of the clusters. We explain the balance of the long-range attraction and repulsion forces which stabilizes the cluster patterns and established the range of parameters, for which the clusters are stable. The cluster is a dissipative structure similar to self-organized Rayleigh–Bénard convective cells. Microdroplet formation plays a role in a variety effects from mist and clouds to aerosols. We anticipate that the discovery of the droplet cluster phenomenon and its explanation will provide new insights on the fundamental physical and chemical processes such as microdroplet role in reaction catalysis in nature as well as new tools for aerosol analysis and microfluidic applications.

Infrared fiber optic evanescent wave spectroscopy for the study of diffusion in the human skin

Fourier Transform Infrared (FTIR) spectroscopic systems make use of Attenuated Total Reflection (ATR) elements for the study of skin in dermatology. FTIR - ATR allows real time and reagent-less analysis of several components, simultaneously. The potential for skin studies is increased by the development of the flexible fiber optic sensor made from infrared transparent polycrystalline silver halide. Segments of fibers can replace the ATR sensing elements inside an FTIR system. Moreover a Fiberoptic Evanescent Wave Spectroscopy (FEWS) can also be used for real time in vivo measurement on skin, in situ. We used FEWS to study the diffusion of UV sunscreen lotions from the outer skin layer into the dermis and epidermis, and used the various absorption bands to differentiate between the behavior of the organic and the water molecules in the lotion. FEWS can be a powerful tool for studying the transport of drugs and cosmetic creams through the skin from the stratum corneum to the dermis and epidermis and for studying the lateral diffusion of various molecules into the skin, in vivo and in real time.

New applications of fiber-optic IR spectroscopy in urologic practice

The objective of this work was to use infrared (IR) fiberoptic spectroscopy for the analysis of urinary salts. Urine samples were obtained (with no sample preparation) from two groups of patients: 24 stone forming patients, after shock wave lithotripsy, and 24 normal subjects of similar ages. IR absorption measurements were performed in real time, using Fiberoptic Evanescent Wave Spectroscopy system, based on IR transmitting silver halide fibers. The absorption data were compared with the IR spectra of aqueous solutions with known concentrations of known urinary salts. The results were then used for the study of the chemical composition of salts in urine samples and for a quantitative analysis of the concentration of these salts. We established the composition of the stones in 20 of the 24 stone forming patients, based on the characteristic absorption peaks for oxalates, carbonates, urates and phosphates observed in their urinary samples. We also determined the concentrations of these salts in the urine samples with average error of 20 percent.

On the Universal Quantitative Pattern of the Distribution of Initial Characters in General Dictionaries: The Exponential Distribution is Valid for Various Languages

Abstract A language is treated as a formal set of characters built into words. The distribution of initial characters in various general dictionaries is uneven. We demonstrate the existence of a consistent general pattern in the distribution of initial characters appearing in various dictionaries. This distribution is satisfactorily described by exponential fitting. The affined languages (related to the same language group) demonstrate close parameters of the exponential fitting curve. A separate treatment of consonants and vowels is instructive. The exponential pattern was registered for the checked physical (paperback) and electronic dictionaries.

Sagging ropes demonstrate transversality conditions of variational problems

We present an account of transversality conditions of variational problems and show how they give rise to essential results in the analysis of different physical phenomena. We find such conditions to be a powerful and elegant approach to a diverse number of variational problems with free endpoints. In this work, we illustrate such condition with the study of a heavy inextensible rope sagging both symmetrically and asymmetrically between two variously shaped, steering-guide wires without friction. In such a situation, the transversality conditions lead to the orthogonality of the rope to the wires at endpoints of the rope, which we confirm experimentally. Freeing the endpoints of the rope yields exact analytical equations that predict the tension of the rope. Heavy ropes whose endpoints are free to slip between arbitrarily shaped, steering wires are discussed.

Infrared fiber optic spectroscopy: a novel tool for skin diagnosis

Fiber Evanescent Wave Spectroscopy (FEWS) is a very useful method for non-invasive and non-destructive biomedical diagnosis. We have developed a FEWS system that makes use of a Fourier Transform Infrared (FTIR) spectrometer and IR transmitting AgBrxCl1-x fibers. The FTIR-FEWS system is compact and easy to use, and it is ideal for the study of the spectroscopy of the skin in the mid-IR. The evanescent wave penetration depth in the mid-IR is comparable with the thickness of the stratum corneum, and therefore the vibrational spectra of lipids, proteins and water can be easily analyzed. We have used FTIR-FEWS for a clinical study of the skin of 60 patients, who had some suspicious skin lesions. Preliminary measurements were carried out both on the lesion and on neighboring healthy areas of the skin, showing some differences in the IR absorption. More data is needed in order to determine the possibility of diagnosis of skin cancer and its type from mid-IR spectral data.

Self-propelling rotator driven by soluto-capillary marangoni flows

The self-propelled, longstanding rotation of the polymer tubing containing camphor continuing for dozens of hours is reported. The rotator is driven by the solutocapillary Marangoni flows owing to the dissolution of camphor. The phenomenological model of self-propulsion is suggested and verified. Scaling laws describing the quasi-stationary self-propulsion are proposed and tested experimentally. The change in the surface tension, arising from the dissolution of camphor and driving the rotator, is estimated as 0.3 mN/m.