Multipoint diffraction strain sensor with variable sensitivity

In our earlier work, a multipoint diffraction strain sensor using a microlens array was developed for measurement of whole-field strains. The method is extended to a system with variable sensitivity and measurement range. In the present system, two collimated laser beams, 3 mm in diameter, symmetrically strike the grating attached to the specimen surface at prescribed angles. The diffracted wavefronts, magnified by a microscope objective, are sampled by a lenslet array with each microlens acting as an individual strain sensor. In-plane strain components over the full field can be measured by what is to our knowledge a new sensor with variable sensitivity by changing the distance from the microscope objective to the microlens array. Both a theoretical explanation and experimental verification are provided.     

Noncompetitive detection of low molecular weight peptides by open sandwich immunoassay

Small peptides with less than 1000 in molecular weight are not considered amenable to sandwich immunoassays due to their difficulty of simultaneous recognition by two antibodies. As an alternative, we attempted noncompetitive detection of small peptides by open sandwich enzyme-linked immunosorbent assay (OS-ELISA) utilizing the antigen-induced enhancement of antibody VH/VL interaction. Taking fragments of human osteocalcin (BGP), a major non-collagen peptide produced in bone, as model peptides, OS immunoassay was performed using the cloned VH and VL cDNAs from two anti-BGP monoclonal antibodies either recognizing the N- or C-terminal fragment, respectively. When the clones were used for OS-ELISA with immobilized VL fragment and phage-displayed VH fragment, enhanced VH/VL interaction upon BGP addition was observed. Especially the clone for the C-terminal fragment showed a superior detection limit as well as a wider working range than those of competitive assay. The result was reproduced with purified VH-alkaline phosphatase and MBP-VL fusion proteins, where the latter was directly immobilized onto the microplate wells. The minimum detectable fragment was the hexamer including the C-terminus. This simple approach with a single monoclonal antibody with a short measurement time may prove a useful tool in immunodiagnostics as well as in proteomics research.     

Heating performance enhancement of a CO2 heat pump system recovering stack exhaust thermal energy in fuel cell vehicles

A CO₂ heat pump system using recovered heat from the stack coolant was provided for use in fuel cell vehicles, where the high temperature heat source like in internal combustion engine vehicles is not available. The refrigerant loop consists of an electric drive compressor, a cabin heater, an outdoor evaporator, an internal heat exchanger, an expansion valve and an accumulator. The performance characteristics of the heat pump system were investigated and analyzed by experiments. The results of heating experiments were discussed for the purpose of the development and efficiency improvement of a CO₂ heat pump system, when recovering stack exhaust heat in fuel cell vehicles. A heater core using stack coolant was placed upstream of a cabin heater to preheat incoming air to the cabin heater. The performance of the heat pump system with heater core was compared with that of the conventional heating system with heater core and that of the heat pump system without heater core, and the heat pump system with heater core showed the best performance of the selected heating systems. Furthermore, the coolant to air heat pump system with heater core showed a significantly better performance than the air to air heat pump system with heater core.     

MEMS needle-type sensor array for in situ measurements of dissolved oxygen and redox potential

Microelectrodes are among the most accurate and reliable monitoring devices for measuring the dynamics of biofilm processes. This paper describes a novel needle-type microelectrode array (MEA) for simultaneous in situ measurements of dissolved oxygen (DO) and oxidation reduction potential (ORP) fabricated using microelectromechanical systems (MEMS) technologies. The MEA exhibits fast response times for both DO and ORP measurements and shows a substantial increase in DO sensitivity. To demonstrate the versatility of the new sensor, it was applied to the measurement of DO and ORP microprofiles in a multispecies biofilm. This work demonstrates that the MEA is able to monitor local concentration changes with a high spatial resolution and provide the versatility of the microelectrode technique needed for biofilm studies as well as the capability for repetitive measurements. In addition, the use of MEMS technologies and batch fabrication approaches enables integration, high consistency, high yields, and mass production. With further development, it may be possible to add additional sensors to the MEA (e.g., pH, phosphate) and integrate them with a reference electrode.     

Perception of Conspecific Female Pheromone Stimulates Female Calling in an Arctiid Moth, <Emphasis Type="Italic">Utetheisa ornatrix</Emphasis>

Perception of the female sex pheromone in Utetheisa ornatrix (Lepidoptera: Arctiidae) is responsible for induction and adjustment of calling by females and the collective phenomenon termed “female pheromonal chorusing”. We found five olfactory-active compounds in the U. ornatrix female gland. When females were exposed to the entire pheromone or to two of its (synthetically prepared) components, (Z,Z,Z)-3,6,9-eicosatriene and (Z,Z,Z)-3,6,9-heneicosatriene, they were more likely to call during a given night, begin calling earlier, and briefly increase signal frequency with which they extrude their abdomen, an observable indication of calling in this species. Some females even initiated calling during photophase when exposed to the pheromone components. In general, female U. ornatrix are more sensitive to the complete blend of pheromone than to its individual compounds. We also tested the hypotheses: 1) that abdominal extrusion per se increases the rate of pheromone release; and 2) that greater abdominal pumping rhythm increases pheromone release rate. Contrary to our expectations: 1) females did not respond more strongly to a pulsed pheromone stimulus than to the constant release of pheromone at the same average release rate; and 2) we did not find a relationship between the frequency of abdominal pumping and pheromone release rate. Possible explanations for these unexpected findings are discussed.     

Biped walking robots created at Waseda University: WL and WABIAN family

This paper proposes the mechanism and control of the biped humanoid robots WABIAN-RIV and WL-16. WABIAN-RIV has 43 mechanical degrees of freedom (d.f.): 6 d.f. in each leg, 7 d.f. in each arm, 3 d.f. in each hand, 2 d.f. in each eye, 4 d.f. in the neck and 3 d.f. in the waist. Its height is about 1.89 m and its total weight is 127 kg. It has a vision system and a voice recognition system to mimic some of the capabilities of the human senses. WL-16 consists of a pelvis and two legs having six 1 d.f. active linear actuators. An aluminium chair is mounted on two sets of its telescopic poles. To reduce the large support forces during the support phase, a support torque reduction mechanism is developed, which is composed of two compression gas springs with different stiffness. For the stability of the robots, a compensatory motion control algorithm is developed. This control compensates for moments generated by the motion of the lower limbs, using the motion of the trunk and the waist that is obtained by the zero moment point concept and fast Fourier transform. WABIAN-RIV is able to walk forwards, backwards and sideways, dance, carry heavy goods and express emotion, etc. WL-16 can move forwards, backwards and sideways while carrying an adult weighing up to 60 kg.     

Annealing characteristics of nanostructured Cu-Fe-P alloy processed by accumulative roll-bonding

Annealing characteristics of a nanostructured copper alloy processed by accumulative roll-bonding (ARB) were studied. A nano-grained Cu-Fe-P alloy processed by 8 cycles of the ARB was annealed at various temperatures ranging from 100 to 400 degrees C for 0.6 ks. The sample still showed an ultrafine grained (UFG) structure up to 250 degrees C, however above 300 degrees C it began to replace by equiaxed and coarse grains due to an occurrence of the conventional static recrystallization. The hardness of the annealed copper decreased largely above 300 degrees C. These annealing characteristics of the UFG copper alloy were compared to those of a high purity copper.     

A frequent activated smoothened mutation in sporadic basal cell carcinomas

Basal-cell carcinomas (BCCs) are the most common cancer in Caucasians. It has been reported that the patched gene is inactivated in 30-40% sporadic BCCs and 20% sporadic medulloblastomas via loss of heterozygosity and nonsense mutations. Recently, two activating smoothened mutations have been found in the sporadic basal cell carcinomas. One, at base pair 1604 (G-to-T transversion) of exon 9, changes codon 535 from tryptophan to leucine, and the other, at base pair 1685 (G-to-A transition) of exon 10, changes codon 562 from arginine to glutamine (Xie et al., 1998). In our study, 1604G-->T was found in 20 out of 97 (20.6%) sporadic BCCs. The high prevalence indicates that 1604G is the mutation hot spot in our tumor samples. This mutation was detected in all three histological subtypes of BCCs, suggesting that smoothened mutation is an early event during the development of the tumor. Our finding of a high smoothened mutation rate, together with high frequent patched gene mutations reported recently, indicates that activation of the hedgehog signal transduction pathway is the most common and early event in the development of sporadic BCCs. Additionally, to determine whether smoothened, like patched, is also involved in the carcinogenesis of medulloblastomas, we screened medulloblastoma samples for these two mutations by restriction analysis. We have found the 1604G-->T mutation in 1 out of 21 medulloblastomas. This result confirmed smoothened gene involvement in the carcinogenesis of medulloblastoma.     

Roles of wave impedance and refractive index in photonic crystalswith magnetic and dielectric properties

We investigated the roles of wave impedance and refractive index in photonic crystals by means of analytical expressions for edges frequencies of a photonic bandgap (PBG) in a one-dimensional photonic crystal with magnetic and dielectric properties. The analytical expressions were derived when the optical thicknesses of layers are the same. The wave impedance governs the formation of PBG's and the intensity of defect modes. Meanwhile, the position of PBG's and the creation of defect modes are related to the refractive index