Evaluation of the concentrations of hydrogen and methane emitted by termite using a semiconductor gas sensor

A gas detection apparatus equipped with a semiconductor gas sensor was employed for qualitative and quantitative measurement of hydrogen and methane emitted by termites. A gas sample of 2.5 ml was injected into the semiconductor gas sensor through the gas detection apparatus, and the maximum voltage of the sensor was converted into gas concentration. The gas samples were collected from three distinct experiments: (1) five combinations of workers and soldiers of Coptotermes formosanus with and without a wood specimen; (2) C. formosanus under six temperature conditions; and (3) four different termite species, C. formosanus, Reticulitermes speratus, Incisitermes minor, and Zootermopsis nevadensis. The hydrogen and methane concentrations increased with an increase in the number of termites. Concentrations were higher in samples with a wood specimen than without it. Both hydrogen and methane concentrations were the highest for the samples at 35 °C and were lowest at 15 and 5 °C. The concentrations were very low at 45 °C because all the termites had died in a few hours. The concentrations of hydrogen and methane were highest for Z. nevadensis, the dampwood termite, among the four species, and no methane was detected for I. minor, the drywood termite, at 28 °C and 75 % RH.     

Dynamic responses of nailed plywood-timber joints under a band-limited white-noise wave

In this study, dynamic tests of nailed plywood-timber joints are conducted under a band-limited white-noise wave using a uniaxial hydraulic shaking table. The principal results are as follows: dynamic responses of nailed plywood-timber joints under a band-limited white-noise wave are reasonably related to the static load-slip relationships and the dynamic responses under harmonic waves of them. When nailed plywood-timber joints are shaken under a composite wave of wide frequency range, they resonate transitionally with one of the frequency components one after another decreasing their equivalent resonant frequencies along their static load-slip curves. Nailed plywood-timber joints are in danger of ultimate failures even though the input maximum accelerations do not exceed their damage limits, if they are shaken for long times with or without intermittences. In this case, nailed plywood-timber joints are prone to fail in low-cyclic bending fatigue failure of nails. Nailed plywood-timber joints, on the other hand, are prone to fail in typical static failure modes when they are shaken under strong input maximum accelerations equivalent to their ultimate limits.     

Dynorphin-Kappa Opioid Receptor Signaling Partly Mediates Estrogen Negative Feedback Effect on LH Pulses in Female Rats

Accumulating evidence suggests that the arcuate nucleus (ARC) kisspeptin/neurokinin B (NKB)/dynorphin (KNDy) neurons play a role in estrogen negative feedback action on pulsatile gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) release. The present study aimed to determine if dynorphin (Dyn) is involved in estrogen negative feedback on pulsatile GnRH/LH release. The effect of the injection of nor-binaltorphimine (nor-BNI), a kappa-opioid receptor (KOR) antagonist, into the third cerebroventricle (3V) on LH pulses was determined in ovariectomized (OVX) adult female rats with/without replacement of negative feedback levels of estradiol (low E₂). The mean LH concentrations and baseline levels of LH secretion in nor-BNI-injected, low E₂-treated rats were significantly higher compared with vehicle-treated controls. On the other hand, the nor-BNI treatment failed to affect any LH pulse parameters in OVX rats without low E₂ treatment. These results suggest that Dyn is involved in the estrogen negative feedback regulation of pulsatile GnRH/LH release. The low E₂ treatment had no significant effect on the numbers of ARC Pdyn (Dyn gene)-,Kiss1- and Tac2 (NKB gene)-expressing cells. The treatment also did not affect mRNA levels of Pdyn and Oprk1 (KOR gene) in the ARC-median eminence region, but significantly increased the ARC kisspeptin immunoreactivity. These findings suggest that the negative feedback level of estrogen suppresses kisspeptin release from the ARC KNDy neurons through an unknown mechanism without affecting the Dyn and KOR expressions in the ARC. Taken together, the present result suggests that Dyn-KOR signaling is a part of estrogen negative feedback action on GnRH/LH pulses by reducing the kisspeptin release in female rats.     

Quantification of phosphatidic acid in foodstuffs using a thin-layer-chromatography-imaging technique

Apical application of lysophosphatidic acid (LPA), a growth-factor-like phospholipid, was shown to prevent or restore gastrointestinal (GI) disorders, such as diarrhea and stomach ulcer, in experimental animals. Because LPA is formed from phosphatidic acid (PA) by the activity of digestive phospholipase A(2), PA is a potential component for dietary treatment of such GI disorders. Here, we quantified PA contained in 38 foodstuffs and 3 herbs by a thin-layer-chromatography-imaging technique. Vegetables belonging to Brassicaceae, such as cabbage leaves (700 nmol/g of wet weight) and Japanese radish leaves (570 nmol/g), contained higher amounts of PA than other foodstuffs. Amounts of PA in fruits, cereals, and starchy root vegetables were below 300 nmol/g. Animal foodstuffs contained low amounts of PA (<60 nmol/g). Interestingly, leaves of Mallotus japonicas, a Japanese edible herb used for treatment of stomach ulcer, had the highest PA (1410 nmol/g) among those examined. The data shown here will be useful for the development of dietary treatment for a damaged GI tract.     

Development of a sustainable evaluation indicator for livestock farming system on the basis of nitrogen flow: a case study on the material flow in livestock farming along with fodder crop production and grazing on abandoned paddy fields

This study was conducted to identify the differences of characteristics of nitrogen flow on the cattle fattening breeders in different types of feeding system. Targeted breeders were classified into fodder-product type and grazing type. In both types, the nitrogen flow during livestock farming was estimated based on the inputs and outputs of materials, and summarized with following three indicators: (1) Flow-Drive Indicator (FDI), indicator for the amplified nitrogen flow per unit of external commercial materials, (2) Artificial Resources Utilization Indicator (AUI), indicator for effects of the inputs of artificial resources on nitrogen flow, and (3) Sustainability Indicator (SI = FDI/AUI), indicator for sustainability of resource utilization. As the results of nitrogen flow analysis, higher average FDI value in the grazing type (2.09) than in the fodder-product type (1.90) showed that the nitrogen from external commercial materials contributed efficiently to increase the nitrogen flow in the grazing type. The average AUI value in the fodder-product type (24.27) was clearly higher than in the grazing types (1.90). It is suggested that fodder-product type was operated by higher dependency of the inputs of utilization of artificial resources. The value of SI was less than 0.2 in the fodder-product type, and it ranged from 1.00 to 1.36 in the grazing type, respectively. It was suggested that the nitrogen flow was completely different in both types of systems, and the grazing type well utilized natural process. Moreover, by comparing the AUI and SI values, it was found that the fodder-product type was operated depending on nitrogen inputs from commercial products. In contrast, the grazing type operated well utilization of nitrogen from natural resources with less input from commercial feed.     

Strain analysis near the cutting edge in orthogonal cutting of hinoki (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>) using a digital image correlation method

A digital image correlation (DIC) method was utilized to measure strain distributed within approximately 0.5 mm of the cutting edge during slow-speed orthogonal cutting of air-dried hinoki (Chamaecyparis obtusa), to clarify the relationships of the strain distribution and cutting conditions, including cutting angle (\(\theta\)) and depth of cut (\(d\)). The strain was measured in 0.04 mm steps, and the measurable minimum strain was approximately 0.08%. Tensile strain of 3% or larger normal to the cutting direction, \({\varepsilon _y}\), tended to extend 0.2 mm or further ahead of the tool when \(\theta \leq 60^\circ\) and \(d \geq 0.1{\text{ mm}}\). This tensile \({\varepsilon _y}\) corresponded to the occurrence of the fore-split in Chip Type I. The tensile \({\varepsilon _y}\) detected along the path of the cutting edge decreased as \(\theta\) and/or \(d\) decreased. Positive shear strain, \({\gamma _{xy}}\), tended to be detected ahead of the tool in Type I. Negative \({\gamma _{xy}}\) tended to be detected ahead of the tool in Type II and III \(\left( {\theta \geq 70^\circ ,\,\,d \geq 0.05{\text{ mm}}} \right)\). These \({\gamma _{xy}}\) values were considered to be related to the elongation and shrinkage of the chip. The study confirmed the usability of the DIC method for the evaluation of cutting conditions and also to classify chip formation into chip types.     

Continuous nondestructive monitoring of larval feeding activity and development of the bamboo powderpost beetle <Emphasis Type="Italic">Dinoderus minutus</Emphasis> using acoustic emission

The life history and feeding biology of the bamboo powderpost beetle Dinoderus minutus remain poorly understood because the beetles’ oviposition, development, and feeding take place inside bamboo culms. In this study, acoustic emission (AE) monitoring was applied for continuous nondestructive analysis of larval feeding activity and development from the first instar to adult eclosion. Newly hatched larvae were inoculated individually into pieces of madake (Phyllostachys bambusoides) culms. AE hits were recorded using single AE sensors fixed onto the bamboo pieces. Generation of AE hits indicated that larval feeding activity had begun after inoculation. Based on the time course of the hourly AE hit rate, the larvae were feeding constantly during each instar, and feeding activity only ceased during periods of ecdysis and pupation. Half of the individuals examined underwent seven instars and the other half underwent eight instars. The time course of AE hit rate per 5 min exhibited periodic cycles, where continuous meals were separated by inactive phases of ca. 5 min, with an average dominant period of each instar ranging between 0.76 and 2.19 h. After correcting the AE data based on distance attenuation of AE waves, the tendency that AE amplitude increased as the larvae developed through ecdysis events became more apparent. AE monitoring continued after adult eclosion, and the feeding activity of the newly emerged adults continued almost ceaselessly during the Reifungsfrass period.     

Risk assessment of ozone impact on the carbon absorption of Japanese representative conifers

A risk assessment of ozone (O₃) impact on the annual carbon absorption (ACA) of Japanese representative conifers was conducted based on the results of an experimental study, monitoring data of oxidant concentrations and vegetation surveys. The areas with high O₃-induced reduction in ACA did not necessarily correspond to the areas with relatively high O₃-exposure. Widespread distribution of O₃-sensitive tree species such as Pinus densiflora and Larix kaempferi, and high ACA were important factors that induced a high risk of O₃ impact on the ACA. Therefore, we concluded that not only the accumulated O₃-exposure but also the variety of tree habitat, the tree sensitivity to O₃ and the ACA among the tree species must be taken into account to assess the risk of O₃ impact on the ACA of Japanese conifers. The O₃-induced reduction in the total ACA of the three tree species in Japan was estimated to be 0.8%.     

Sensitivity to cadmium of the standard test species Folsomia candida compared to two other species, Onychiurus yodai and Sinella umesaoi (Collembola)

Knowing whether test species used for single-species toxicity tests are representative of other species provides valuable information because contaminant effects are often extrapolated to the community level based on these tests. To evaluate how representative the sensitivity of the standard test collembolan species Folsomia candida is for Collembola, we devised toxicity tests using the collembolan species Onychiurus yodai and Sinella umesaoi, which exhibit life-forms different from F. candida. Sensitivity to cadmium (Cd) was compared between F. candida and the novel test species. The 50% effective concentrations for reproduction were 154.7, 72.2 and 40.9 mg Cd/kg dry soil for O. yodai, F. candida and S. umesaoi, respectively. Thus, the reproductive sensitivity of F. candida to Cd was between that of the other two species. Increasing reproductive sensitivity to Cd corresponded to increasing activity levels and a more surface-dwelling life-form. Our data may facilitate the generalisation of effect data for F. candida to other species.