Bonding of densified beech wood using adhesives based on thermally modified soy proteins

The bondability/glueability of aged and sanded thermo-hydro-mechanically (THM) densified beech wood (Fagus sylvatica L.) was tested and compared with undensified sanded beech wood as a control. THM and control specimens were bonded with five different soy protein isolate (SPI) based adhesives. Commercial SPI powder was thermally modified in the vacuum chamber at 50 or 100?°C and pH adjusted (to pH 10.0) dispersions in water prepared at 24, 50 or 90?°C. Wettability was determined with measuring the sessile drop contact angles of water. Effective penetrations (EPs) and tensile shear strengths of THM and control specimens were determined. THM and control wood had similar wettability. Although THM wood had lower moisture content than control wood, it absorbed the water more slowly than control wood. THM specimens showed lower EPs than control specimens when comparing individual adhesives due to increased density of THM wood. Adhesives prepared with SPI thermally modified at 50?°C showed statistically significantly lower tensile shear strength of bonded THM specimens than that of bonded control specimens. THM densification had no significant effect on the bonding strengths of adhesives prepared with non-modified SPI and SPI thermally modified at 100?°C.     

How to improve the economy of bioethanol production in Serbia

Bioethanol accounts for the majority of biofuel use worldwide, either as a fuel or a gasoline enhancer. In Serbia, the industrial production of bioethanol still relies on conventional feedstocks containing starch and sugar such as corn, wheat and molasses. In order to improve the economy of bioethanol production and to avoid the competition of the feedstock utilization for food and energy, several production approaches based on crop selection, process integration and waste utilization were considered in this paper. Particular attention was put on utilization of non conventional crops such as triticale and damaged crops not appropriate for food consumption. Potential of lignocellulosic biomass for the production of second generation ethanol in Serbia was also considered as well as the utilization of stillage as a main by-product. The investigated approaches can significantly improve the economy of bioethanol production and contribute to solve serious environmental problems.     

Design and implementation of UWB CMOS LC filters LNA for carrier less impulse radio receivers

The design and the implementation of Ultra-wide-band (UWB) CMOS LC filter LNA for Ultra Wide Band carrier less Impulse Radio receivers is presented. Architectures for both single ended and differential ended LNA are proposed for small fractional bandwidths such as the ECC frequency band and for large fractional bandwidths such as FCC frequency band. Simple guidelines to achieve large voltage gain and low noise figure are given. The implementation in standard CMOS technologies in the context of integrated receivers is discussed and simple layout rules allowing reliable designs are proposed. Several LNA prototypes for different fractional bandwidths have been fabricated in a 0.13 μm CMOS technology. Measurement results agree well with the simulations.     

Derivatives of apomorphine and of other N-substituted norapomorphines

Derivatives of apomorphine and of N-n-propylnorapomorphine were prepared to obtain modified pharmacological activity and enhanced chemical stability. Mouse profile and dog emesis screens were performed, and the activity of various N-substituted derivatives and their esters was evaluated and compared to the parent compounds. The N-n-propyl diacetate derivative and N-methyl and N-n-propyl ascorbate salts were remarkably stable to air: apomorphine etherate was no more stable than the free base. The dimers, the major products formed during the acid-catalyzed rearrangement of morphines to apomorphines, were all potent emetics. Additionally, two showed a significant antagonism to morphine in mice and dogs.     

From functional food to medicinal product: Systematic approach in analysis of polyphenolics from propolis and wine

In the last decade we have been working on standardization of propolis extract and determination of active constituents of wine those are rich in polyphenolics and have nutritional as well as therapeutic value. Here we are summarizing our results and providing overview on systematic approach how to analyse natural products rich in flavonoids and phenolic acids.     

On the stability of DC-to-DC converters in photovoltaic systems undergoing sliding motions

This paper deals with the dynamic behaviour of different DC-to-DC switching electronic converters in photovoltaic applications. In particular, the ability of the DC-to-DC converters to accomplish regulation of certain circuit variables, which are related to the control objectives, is examined. This task is addressed from a variable structure system approach. With this aim, the feasibility of establishing stable sliding regimes on different state co-ordinate surfaces is investigated. Differences in the dynamic behaviour of the DC-to-DC switching converters between photovoltaic and conventional power-supply applications are stressed.     

Energy-based approach to the output feedback control of wind energy systems

Wind energy systems can be classified into constant speed and variable speed ones. In constant speed schemes, the generator is directly connected to the electric grid. On the other hand, variable speed operation can be accomplished interposing a static converter in the energy flow between the generator and the grid, permitting a high control flexibility. The main control objectives are the maximization of the conversion efficiency and the elimination of torque oscillations propagated through the drive train. It is assumed in this paper that the most flexible part of the system lies on the turbine, constraining the control solutions to generator speed feedback. The control task is addressed from a passivity-based control viewpoint. The drive train dynamics is modelled as a port-controlled Hamiltonian system with dissipation. Then, stabilization of the desired operating point is achieved through energy shaping and damping injection. Depending on the damping matrix assignment, different control solutions are recovered. Finally, a dynamic feedback controller which preserves the system structure is proposed to improve the system performance without measuring the wind velocity.     

Drawing database schemas

A wide number of practical applications would benefit from automatically generated graphical representations of database schemas, in which tables are represented by boxes, and table attributes correspond to distinct stripes inside each table. Links, connecting attributes of two different tables, represent referential constraints or join relationships, and may attach arbitrarily to the left‐ or to the right‐hand side of the stripes representing the attributes. To our knowledge no drawing technique is available to automatically produce diagrams in such a strongly constrained drawing convention. In this paper we provide a polynomial time algorithm for solving this problem, and test its efficiency and effectiveness against a large test suite. Also, we describe an implementation of a system that uses such an algorithm and we study the main methodological problems we faced in developing such a technology. Copyright © 2002 John Wiley & Sons, Ltd.