Low-energy laser irradiation stimulates bone nodule formation at early stages of cell culture in rat calvarial cells

AIMS: To investigate the pharmacokinetics of the antimalarial artemisinin in the field setting using sparsely collected data. METHODS: Artemisinin concentrations were determined by h.p.l.c. in a total of 107 capillary plasma samples collected on the first day and in 33 samples on the last day of a 5-day oral artemisinin regimen of 10 mg kg(-1) day(-1) in 23 paediatric (aged 2-12 years) and 31 adult (aged 16-45 years) Vietnamese patients with uncomplicated falciparum malaria. The population model was developed using NONMEM, incorporating interoccasion variability and accounting for a systematic change in artemisinin pharmacokinetics with time, modelled as a change in oral bioavailability. RESULTS: Clinical efficacy, in terms of parasite clearance and fever subsidence times, was comparable between children and adults. A one-compartment model with separate pharmacokinetic estimates for children and adults was found best to describe the disposition of artemisinin after oral administration. The population estimates for artemisinin clearance and distribution volume, respectively, were 432 1 h(-1) and 16001 for adults and 14.41 h(-1) kg(-1) and 37.91 kg(-1) for children, with an intersubject variability (collectively for both age groups) of 45% and 104%, respectively. The oral bioavailability was estimated to decrease from Day 1 to Day 5 by a factor of 6.9, a value found to be similar for children and adults. CONCLUSIONS: Artemisinin pharmacokinetic data was successfully derived in both paediatric and adult patients using 2-3 capillary blood samples taken in conjunction with parasitaemia monitoring. This study's findings advocated the dosing of artemisinin to children according to bodyweight and to adults according to a standard dose.     

Effects of water vapor in the oxidative dehydrogenation of isobutyric acid to methacrylic acid over iron phosphate catalyst

The effects of water vapor on the oxidative dehydrogenation of isobutyric acid to methacrylic acid over an iron phosphate catalyst were studied. The presence of water vapor suppresses both the carbon deposit and the formation of phosphorus-rich species on the surface of the catalyst and, as a result, it prevents the degradation in both the catalytic activity and the selectivity which occurs during the reaction, though it has no clear influence on both the redox properties and the structure of the catalyst. The pretreatment of the catalyst with a gas containing water vapor or the reaction in the presence of water vapor restores the activity and selectivity of the degraded catalyst. It is proposed that water plays a role in removing the carbon and oxygenated products from the surface, in suppressing the side reaction, that is, the decomposition of isobutyric acid to propylene and CO, and also in modifying the surface species.     

Synthesis and antibacterial activity of copolymers having a quaternary ammonium salt side group

Copolymers with a quaternary ammonium salt side group have been prepared from vinylbenzyl–cetyldimethylammonium chloride and acrylonitrile and their antibacterial activity has been examined with Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. Growth inhibitory effect has been found to increase with the increase in the quaternary ammonium salt concentration in the copolymer. The effect is small on gram-negative bacteria and large on gram-positive bacteria.     

Supporting efficient multimedia database exploration

Due to the fuzziness of query specification and media matching, multimedia retrieval is conducted by way of exploration. It is essential to provide feedback so that users can visualize query reformulation alternatives and database content distribution. Since media matching is an expensive task, another issue is how to efficiently support exploration so that the system is not overloaded by perpetual query reformulation. In this paper, we present a uniform framework to represent statistical information of both semantics and visual metadata for images in the databases. We propose the concept of query verification, which evaluates queries using statistics, and provides users with feedback, including the strictness and reformulation alternatives of each query condition as well as estimated numbers of matches. With query verification, the system increases the efficiency of the multimedia database exploration for both users and the system. Such statistical information is also utilized to support progressive query processing and query relaxation. Received: 9 June 1998/ Accepted: 21 July 2000 Published online: 4 May 2001     

A dynamic simulator for dispatcher training

A dynamic simulatir for power system dispatcher's training was recently developed in Japan. To date, this training simulator has been implemented in two Japanese power utility companies. To give trainees realistic simulation, the training simulator provides the same human-machine interface as that for the actual dispatcher, and calculates the dynamics of the power network in much the same way as the actual dispatcher sees them and with the same time resolution. For this a modern 32-bit computer was used, and a fast AC load flow program was developed. For smooth simulation the whole simulation was designed to comprise five phases, i.e. scenario registration, scenario selection/modification, static simulation, dynamic simulation and evaluation.     

Experimental Study of the Viscous Pump with a Helical Channel Rotor： Torsion Effect of the Channel

The viscous pump, which has a rotor with a helical square channel, is studied experimentally. The non-dimensional channel curvature is taken to be about 0.1. Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics. We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump. We also observe the secondary flow at a crosssection of the channel. Some of the results obtained are shown as follows： The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation, and becomes small when the favorable rotation of the rotor to the flow is applied. As for the secondary flow in a cross-section, there appear several types of vortex. When there is no rotation, the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex, but it changes to a four-vortex type when the flux is large. The secondary flow becomes asymmetric as the rotation is applied. We have unsteady flow patterns at large flux and rotation.     

Influence of Cyclic Strain-Hardening Exponent on Fatigue Ductility Exponent for a Sn-Ag-Cu Micro-Solder Joint

The fatigue ductility exponent in the Coffin–Manson law for a Sn-Ag-Cu micro-solder joint was investigated in terms of the cyclic strain-hardening property and the inelastic strain energy in fracture for isothermal fatigue. The fatigue ductility exponent was found to increase with temperature and holding time under strain at high temperature. This exponent is closely related to the cyclic strain-hardening exponent, which displays the opposite behavior in that it decreases with increasing temperature and with coarsening of intermetallic compound particles while holding under strain at high temperature. This result differs from the creep damage mechanism (grain boundary fracture), which is a primary reason for the significant reduction in fatigue life for all strain ranges for large-size specimens.     

Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Upward in Small Rectangular and Triangular Tubes

In the present study, experiments were performed to examine the characteristics of flow boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically upward in small copper rectangular and triangular tubes with hydraulic diameters of 1.04 and 0.88 mm, respectively, for the development of a high-performance heat exchanger using small tubes or minichannels for air-conditioning systems. Their characteristics were clarified by comparing the previous experimental data of the small circular tube (1.00 mm internal diameter). In the rectangular and triangular tubes, the pressure drop was found to be slightly lower and the heat transfer was much better than in the circular tube.     

Influence of Asymmetrical Waveform on Low-Cycle Fatigue Life of Micro Solder Joint

The effects of waveform symmetry on the low-cycle fatigue life of the Sn-3.0Ag-0.5Cu alloy have been investigated, using micro solder joint specimens with approximately the same volume of solder as is used in actual products. Focusing on crack initiation life, fatigue tests on Sn-Ag-Cu micro solder joints using asymmetrical triangular waveforms revealed no significant reduction in fatigue life. A slight reduction in fatigue life at low strain ranges caused by an increase in the fatigue ductility exponent, which is the result of a weakening microstructure due to loads applied at high temperature for long testing time, was observed. This was due to the fact that grain boundary damage, which has been reported in large-size specimens subjected to asymmetrical triangular waveforms, does not occur in Sn-Ag-Cu micro size solder joints with only a small number of crystal grain boundaries.