Effect of ethyl-α-hydroxymethylacrylate on selected properties of copolymers and ACP resin composites

There is an increased interest in the development of bioactive polymeric dental composites and related materials that have potential for mineralized tissue regeneration and preservation. This study explores how the substitution of ethyl alpha-hydroxymethylacryate (EHMA) for 2-hydroxyethyl methacrylate (HEMA) in photo-activated 2,2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy)phenyl]propane (Bis-GMA) and Bis-GMA/tri(ethylene glycol) dimethacrylate (TEGDMA) resins affected selected physicochemical properties of the polymers and their amorphous calcium phosphate (ACP) composites. Rate of polymerization and the degree of conversion (DC) of polymers {EHMA (E), HEMA (H), Bis-GMA/EHMA (BE), Bis-GMA/HEMA (BH), Bis-GMA/TEGDMA/EHMA (BTE) and Bis-GMA/TEGDMA/HEMA (BTH)} were assessed by photo-differential scanning calorimetry and Fourier-Transform Infrared (FTIR) spectroscopy. ACP/BTE and ACP/BTH composites were evaluated for DC, biaxial flexure strength (BFS), water sorption (WS) and mineral ion release. Mid-FTIR and near-IR measurements revealed the following order of decreasing DC: [E, H polymers (97.0%)] > [BE copolymer (89.9%)] > [BH copolymer (86.2%)] > [BTE, BTH copolymers (85.5%)] > [ACP/BTH composite (82.6%)] > [ACP/BTE composite (79.3%)]. Compared to HEMA, EHMA did not adversely affect the BFS of its copolymers and/or ACP composites. Lower WS of BTE copolymers and composites (28% and 14%, respectively, compared to the BTH copolymers and composites) only marginal reduced the ion release from ACP/BTE composites compared to ACP/BTH composites. More hydrophobic ACP composites with acceptable ion-releasing properties were developed by substituting the less hydrophilic EHMA for HEMA.     

A Furnace Control System for Tracing Reference Reheating Curves

A control system for tracing the reference reheating curves of individual steel slabs in continuous furnaces is presented. The system enables the predefined, controllable reheating of slabs in a furnace. The slab temperatures are obtained by the simulation of a mathematical model of the slab‐reheating process. The interior of the continuous furnace is divided into six control zones. The individual zone temperatures are adjusted by the control system in such a way that the temperatures of the slabs in the zone are as close as possible to the desired slab temperatures. To take into account delays in the production line and to synchronize the furnace with the rolling mill's capacities, a time shift of the reference reheating curves and a prolonged drop‐out interval are introduced.     

Experience on Pre-Series and Series Production of LHC Dipoles Cold Masses in ASG Superconductors

In 1986 Ansaldo Magnet Dept. (now ASG Superconductors) started, in cooperation with CERN, the design activities of the first 1 m-8 T LHC prototype dipoles. After several design steps and the manufacturing of 1+3 prototype dipoles 10 m long, the final design configuration 15 m long was defined by CERN. During the following years, a very close collaboration with CERN engineers and technicians lead to define the parameters about the most critical manufacturing processes, in particular winding of s.c. cable, collaring of coils, cold mass welding and test procedures. In the meantime, installation and commissioning of all the manufacturing plants followed: winding machines, curing presses, collaring press and welding press were installed, as well as geometrical measurements stations and vacuum chamber for leak test. Finally two manufacturing halls were fully dedicated to LHC dipoles production. At the beginning of year 2002, all the manufacturing plants were coming to be operational, ready to start the large scale production of LHC cold masses: 30 pre-series, 386 series and 30 spare cold masses have been produced till May 2007, to get a total number of 446 cold masses. In this paper we summarize all the data collected during a five years production: main manufacturing data, test results and production rate are presented. Final results about tests performed at CERN in superfluid He at 1.9 K are also included as well as correlation between test result and manufacturing rate.     

Extrusion of a hard-to-cook bean (Phaseolus vulgaris L.) and quality protein maize (Zea mays L.) flour blend

Heated extrusion was tested as an alternative process for incorporating “hard-to-cook” beans into food products. A 3² factorial design was used to evaluate extrusion conditions for a 40/60 (w/w) blend of “hard-to-cook” beans and quality protein maize. Tested extrusion variables were temperature (155, 170 and 185 °C) and moisture content (15.5, 17.5 and 19.5 g/100 g). Screw speed was fixed at 130 rpm. The extrudates obtained at 155 and 170 °C with 15.5% moisture had the best physical characteristics and were chosen for comparative analysis of nutritional changes between the unprocessed “hard-to-cook” bean/quality protein maize flour blend and the resulting extrudates. In vitro protein digestibility was higher in the extrudates (80%) than in the flour blend (76%). In vitro starch digestibility was higher at 155 °C (89%) and 170 °C (92%) than in the flour blend (12%). Processing conditions decreased dietary fibre content by 38% at 155 °C and 44% at 170 °C.     

DV Based Positioning in Ad Hoc Networks

Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute position of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding position without the aid of GPS in each node of an ad hoc network is important in cases where GPS is either not accessible, or not practical to use due to power, form factor or line of sight conditions. Position would also enable routing in sufficiently isotropic large networks, without the use of large routing tables. We are proposing APS – a localized, distributed, hop by hop positioning algorithm, that works as an extension of both distance vector routing and GPS positioning in order to provide approximate position for all nodes in a network where only a limited fraction of nodes have self positioning capability.     

Two Degrees of Freedom in the Control of a DC-DC Boost Converter,Fuzzy Identified Explicit Model in Feed-forward Line

We present a novel approach to the fuzzy control of a DC-DC Boost Converter. Using heuristic partitioning of the main control parameters and focusing on global knowledge of the open-loop, stable system’s equilibriums, the new method is developed based on an offline fuzzy identification of the steadystate duty cycle. The explicit and the fuzzy identified global model of the duty cycle robustly contribute to the system’s stability, even in the presence of large changes to the process parameters. In comparison with the analytically derived duty cycle using two different methods, the identified model prediction of an infinity horizon duty cycle shows better precision. These results are achieved in an analysis of the converter’s hybrid-simulation model where the assumptions made in the mathematical modelling are minor in comparison with similar assumptions in physical examples. The steady-state error compensation relies on the optimized PI controller, which is independently constructed and involved in the final Two-Degreesof-Freedom (TDOF) controller. The successful simulation results agree with the robustness and present a DC-DC converter with stable operation, even in the dynamic exchange of the DCM (Discontinuous Conduction Mode) and CCM (Continuous Conduction Mode). The method is widely applicable as it minimizes the real time of processing and avoids over-determined solutions.     

How to Study Biofilms after Microbial Colonization of Materials Used in Orthopaedic Implants

Over the years, various techniques have been proposed for the quantitative evaluation of microbial biofilms. Spectrophotometry after crystal violet staining is a widespread method for biofilm evaluation, but several data indicate that it does not guarantee a good specificity, although it is rather easy to use and cost saving. Confocal laser microscopy is one of the most sensitive and specific tools to study biofilms, and it is largely used for research. However, in some cases, no quantitative measurement of the matrix thickness or of the amount of embedded microorganisms has been performed, due to limitation in availability of dedicated software. For this reason, we have developed a protocol to evaluate the microbial biofilm formed on sandblasted titanium used for orthopaedic implants, that allows measurement of biomass volume and the amount of included cells. Results indicate good reproducibility in terms of measurement of biomass and microbial cells. Moreover, this protocol has proved to be applicable for evaluation of the efficacy of different anti-biofilm treatments used in the orthopaedic setting. Summing up, the protocol here described is a valid and inexpensive method for the study of microbial biofilm on prosthetic implant materials.     

Circuiti autonomi nonsingolari din elementi binari,realizzabili medianten elementi a soglia

The linear separability concepts are applied in order to give either necessary or sufficient conditions for realizability by exactlyn threshold elements of a given coded cycle set of an autonomous nonsingular sequential circuit, specified byn boolean functions. Two main classes are obtained, the self-dual and the pure majority classes corresponding respectively to a necessary and to a sufficient condition. Also “necklace” circuits are described which exhibit remarkable properties. The number ofrealizable, non singular autonomons circuits are enumerated up ton=5, and one investigates also the capability of circuits ofn threshold elements to perform a state cycle of length2 ⁿ. Finally, in Appendix I, a constructive method to generate a non singular transition table is given.

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Questa ricerca è stata finanziata in parte dall' U.S.A.F. sotto il Grant n. 65-44 tramite l'European Office, Office of Aerospace Research-Brnxelles.     

Topographical evaluation of the phenotype of spontaneous behaviour in mice with targeted gene deletion of the D1A dopamine receptor: paradoxical elevation of grooming syntax

The phenotype of spontaneous behaviour in mice with targeted gene deletion of the DIA dopamine receptor was investigated topographically. Via direct visual observation, individual elements of behaviour were resolved and quantified using an ethologically-based, rapid time-sampling behavioural check-list procedure. Relative to wildtypes (D1A+/+), D1A-null (-/-) mice evidenced over initial exploration significant reductions in rearing free, sifting and chewing, but significant increases in locomotion, grooming and intense grooming. Sniffing and rearing to a wall habituated less readily in D1A-null mice such that these behaviours occurred subsequently to significant excess: increases in locomotion were persistent. The ethogram of spontaneous behaviour in D1A-null mice was characterised by neither 'hypoactivity' or 'hyperactivity' but, rather, by prominent topographical shifts between individual elements of behaviour that could not be encapsulated by either term. Given the substantial body of evidence that grooming and particularly intense grooming constitute the most widely accepted behavioural index of D1-like receptor function, the elevation of such behaviour in D1A-null mice was paradoxical; it may reflect (over)compensatory processes subsequent to developmental absence of D1A receptors and/or the involvement of a D1-like receptor other than/additional to the D1A subtype.