Two novel betaine derivatives from Kancolla seeds (Chenopodiaceae)

Analysis of the polar extracts from kancolla seeds led to the isolation of five betaines: glycine betaine, trigonelline, trigonelline methylester, trigonelline glucosylester and 3-carboxy-1-(2-sulfoethyl)-pyridinium, the last two of which have not previously been reported in the literature. All structures were elucidated from spectroscopic [NMR (¹H, ¹³C, COSY, HOHAHA, HMQC, HMBC)] and mass spectrometric data (ESI-MS).     

A 3-DOF testing machine for in-plane behaviour of structures

A testing machine designed for studying the in-plane behaviour of structures controlling independently (either in load and in displacement) three degrees of freedom is presented. The main topics herein discussed are (i) limits of application, either due to the capability of jacks, transducers and rollers, and to local and global equilibrium; (ii) behaviour in the case of brittle failure, with particular regard to energy and displacement restitution due to the elastic behaviour of the machine itself and to oil deformability; and (iii) the control system, which is based on the classic scheme for feedback control systems and has a separate sub-system to keep under control the security devices.     

Pyrolysis Kinetics for the Conversion of a Polymer into an Amorphous Silicon Oxycarbide Ceramic

We present experimental and analytical results for the pyrolysis reactions underlying the conversion of a cross-linked polymer into an amorphous ceramic material. The activation energies, obtained from thermogravimetric data, and chemical analysis of the volatiles by mass spectroscopy are used to identify the reaction pathways. The reaction is determined to be first-order, which is consistent with its solid-state nature. The magnitude of the weight loss is analyzed to calculate the number of molecular sites in the polymer that participate in the reaction. The experiments were conducted on a polymer made from silsesquioxanes that convert into silicon oxycarbide ceramics on pyrolysis. The results show that <2.5% of the silicon atoms in the polymer are removed as volatile silanes, and less than one-half of the carbon atoms are lost as methane. These results are a first step in understanding the molecular basis for the ceramic yield, as well as the evolution of the nanostructure as the material changes from an organic into a ceramic state by reactions that can occur at <850°C.     

Changes in Abundance and Growth Characteristics of White Perch from the Mouth of the Bay of Quinte

White perch became established in Lake Ontario in the 1950s, and by the mid 1960s were a major commercial species in the Bay of Quinte area. Commercial catches have fluctuated markedly, ranging from approximately 60,000 to 230,000 kg/yr between 1964 and 1978. Experimental trap nets set inshore of the mouth of the Bay of Quinte during May to July suggest a decline in white perch abundance from 1973 through 1978. However, the commercial catch did not similarly decline until 1979 when the commercial catch fell to a low of 30,000 kg/yr. The reason for this difference may be due to the fact that the bulk of the commercial catch is harvested during the winter when white perch congregate at the mouth of the bay, making fishing relatively productive. The growth of white perch was also considered, based on back-calculated growth curves of white perch caught in the experimental nets. Lee's phenomenon—a tendency for back-calculated lengths at a given age to become progressively smaller as the age of the fish from which they were computed increases—was apparent among the fish caught during this study although lacking in an earlier study. Due to the size selective nature of the fishery, an increased commercial harvest in recent years may have removed a disproportionate number of faster growing individuals from the population.     

A criterion for experimental validation of slip-flow models for incompressible rarefied gases through microchannels

This paper is devoted to analysing the friction factor for incompressible rarefied gas flow through microchannels. A theoretical investigation is conducted in order to underline the conditions for experimentally evidencing rarefaction effects on the pressure drop. It is demonstrated that for a fixed geometry of the microchannel cross-section, it is possible to calculate the minimum value of the Knudsen number for which the rarefaction effects can be observed experimentally, taking into account the uncertainties related to evaluation of the friction factor.     

Comparison and electrical modeling of new polymeric cellular electrets

A new family of cellular polymers-that, upon appropriate charging, reveals interesting piezoelectric properties-has been developed recently. Its major characteristic is thermal stability up to high temperatures, which broadens the potential field of application. These materials become electrets upon charging under high levels of electric field. Investigation of charging mechanisms is fundamental to reach optimization of electret and piezoelectric properties. This paper presents results and considerations relevant to contact charging of these new materials, pointing out the relation between partial discharge and space charge formation, as well as time and temperature stability of electret properties. The concepts of threshold for partial discharge inception and space charge accumulation, the modeling of avalanches in cavities, and the rate of charge generation are exploited trying to explain charging mechanism and, therefore, they provide useful indication for optimization of material manufacturing.     

Crystallisation kinetics and morphology of high density polyethylene containing organic and inorganic pigments

Some organic pigments, present in very small amounts (0.1 to 0.2%), can cause warpage and shrinkage phenomena in moulded parts of linear polyethylene. Investigations on such phenomena have been carried out by dilatometric and morphological analysis. The influence on polyethylene crystallisation kinetics and morphology of such organic and inorganic pigments, which do not cause any deformation effect, has been studied. The experimental results show that only organic pigments increase the crystallisation rate, by acting as nucleating agents; in these cases, moreover, the crystalline grain is smaller and the typical morphology of polyethylene crystallised in bulk is altered. A possible correlation between the nucleating action and the warpage effect of organic pigments on moulded polyethylene is discussed.     

Friction,adhesion and durability and influence of humidity on adhesion and surface charging of skin and various skin creams using atomic force microscopy

Skin cream is commonly used to improve skin health and create a smooth, soft and moist perception by altering the surface roughness, friction, adhesion, elasticity and surface charging of skin surface. In this study, we present the first systematic study on friction, adhesion, durability and influence of humidity on adhesion and surface charging of skin and various skin creams using atomic force microscopy. Skin is subjected to various daily activities with time, and the durability is closely tied to product compositions. Durability of various skin creams was studied by repeated cycling tests. In order to better understand the frictional behaviour, the dynamic viscosities of various skin creams were measured. Skin cream thinly coats the skin surface and can cause drastic changes in the mechanical properties. In addition to mechanical properties, adhesive force is one of the important factors in determining the tactile perception of skin cream and is directly affected by the film thickness. Because the environmental dependence of skin and skin cream is of importance, the influence of humidity on adhesive force, film thickness and Young's modulus mapping were measured using force distance technique. The health and feel of skin are significantly affected by its surface charging, the surface potential of skin and various cream‐treated skins was measured using the Kelvin probe method.     

Phase-Sensitive Reflective Imaging Device in the mm-wave and Terahertz Regions

Two Free Electron Laser sources have been developed at ENEA-Frascati for a variety of applications: A Compact Free Electron Laser (C-FEL) that provides coherent radiation in the frequency range between 90 and 150 GHz Gallerano et al. (Infrared Phys. and Techn. 40:161, 1999), and a second source, FEL-CATS, which utilizes a peculiar radio-frequency structure to generate coherent emission in the range 0.4 to 0.7 THz Doria et al. (Phys. Rev. Lett 93:264801, 2004). The high peak power of several kW in 15 to 50 ps pulses, makes these sources particularly suitable for the assessment of exposure limits in biological systems and for long range detection. In this paper we present a phase-sensitive reflective imaging device in the mm-wave and THz regions, which has proven to be a valuable tool in the biological Ramundo-Orlando et al. (Bioelectromagnetics 28:587–598, 2007), environmental Doria et al. (2005) and art conservation fields Gallerano et al. (2008). Different setups have been tested at different levels of spatial resolution to image objects from a few centimeter square to larger sizes. Images have been compared to identify and characterize the contrast mechanism.