Peierls mechanism of the metal-insulator transition in ferromagnetic hollandite K2Cr8O16

Synchrotron x-ray diffraction experiment shows that the metal-insulator transition occurring in a ferromagnetic state of a hollandite K(2)Cr(8)O(16) is accompanied by a structural distortion from the tetragonal I4/m to monoclinic P112(1)/a phase with a √2×√2×1 supercell. Detailed electronic structure calculations demonstrate that the metal-insulator transition is caused by a Peierls instability in the quasi-one-dimensional column structure made of four coupled Cr-O chains running in the c direction, leading to the formation of tetramers of Cr ions below the transition temperature. This provides a rare example of the Peierls transition of fully spin-polarized electron systems.

Visible Electroluminescence from Pn Junction Type μc-Sic/ Porous Si / c-Si Structures

We have fabricated two kinds of n-type microcrystalline silicon carbon (μc-SiC) / porous silicon (PS) / p-type crystalline silicon (c-Si) pn junctions and demonstrated a visible light emission from them. We have observed three types of visible light emission; an uniform red light emission at a forward current above 12mA/cm2 for the pn junction using a 0.2–0.4 Qcm c-Si substrate, and a very weak white light emission at a forward current of about 90 mA/mm2 and a strong orange-red light emission at a forward current from 200 to 619 mA/mm2for the pn junction using a 3.5–4.5 Ωcm c-Si substrate.

A possible animal model for critical colonisation

OBJECTIVE

To develop a critical colonisation model in rats that will facilitate investigation of its pathophysiology and the development of new and effective diagnosis and treatment protocols.

METHOD

Three groups of rats were given full-thickness dorsal wounds: a control group received phosphate-buffered saline; an experimental group was inoculated with Pseudomonas aeruginosa; an infection group with streptozotocin-induced diabetes was also inoculated with P. aeruginosa. All groups were assessed on a number of parameters at days 1, 3, 5 and 7 following wounding. Parameters included gross observations, histopathological observations, quantification of redness and swelling, serum C-reactive protein (CRP) measurement and tissue bacterial counts.

RESULTS

Healing was delayed in the experimental group when compared with the control group, with no signs of inflammation. Although the numbers of bacteria were similar in the experimental and infection groups, polymorphonuclear neutrophil (PMN) infiltration was localised to granulation tissue in the experimental group, whereas it extended to muscular tissue in the experimental group. CRP levels remained low in the experimental group.

CONCLUSION

These findings suggest that the inoculation of bacteria provides a possible model of critical colonisation in rats. We believe this will contribute to a better understanding of critical colonisation.

High-efficiency genetic transformation of maize by a mixture of pollen and exogenous DNA

High-efficiency genetic transformation was induced in a genetic stock of maize, Zea mays Linnaeus, by self-pollination of the recipient plants along with DNA of the donor. The highest frequency of transformed endosperm per ear was 9.29%. DNA was applied onto silks in a pollen/DNA pasty mixture. The exogenous DNA transferred into endosperm expressed itself in endosperm formation. It is not known, however, whether the exogenous DNA segment in endosperm had been incorporated or whether it was present in the nucleus additionally, fragmentally, or in some other state. It was revealed that all of four possible cases had occurred as follows: exogenous DNA was transferred into (i) both embryo and endosperm of the same kernel, (ii) embryo only, (iii) endosperm only, and (iv) neither embryo nor endosperm. It was also revealed that exogenous DNA that had entered into the embryo had been maintained through embryo formation, germination, vegetative growth and differentiation, and reproductive growth, and finally was manifested in embryo and/or endosperm of the following generation and acted in endosperm formation. The frequency of transformed endosperm in this generation, however, was rather low. It may be that exogenous DNA taken into the embryo was unstable.

Development of a method to control the water evaporation of hatching eggs during incubation

Three experiments were conducted to develop methods to control the amount of water loss and to evaluate the metabolic effects of water condition in the White Leghorn breeder eggs during incubation. One hundred twenty, 54, and 90 Julia strain White Leghorn breeder eggs were incubated at 37.8 degrees C, 60% RH in experiments 1, 2, and 3. In experiment 1, eggs were drilled with various bore diameters of 0, 0.5, 1, 2, 3, 4, and 5 mm on the blunt end of the eggshell. In experiment 2, 4 x 4 mm(2) windows were cut into the eggs or the eggs were drilled with 5 holes of bore diameter 2 mm on the blunt end of eggshell. In experiment 3, eggs were drilled with 1, 3, 5, and 7 holes of diameter 2 mm on the blunt end of eggshell. Eggs were treated on d 3 of each experiment and the amount of water loss was recorded on d 19 of incubation. Embryo growth was evaluated in experiments 2 and 3. In addition, the livers of embryos were collected in the 0-, 1-, 3-, and 5-hole treatment groups after weighing eggs to determine 3-hydroxy acyl coenzyme A dehydrogenase activity. In experiment 1, although higher water loss was observed in all windowed eggs than in control, there were no differences in amount of water loss among all bore diameters. Accordingly, that was not successful to control amount of water loss. In experiment 2, higher water loss was observed in drilled eggs at the same levels in windowed eggs as in control. Drilling holes was a more useful treatment to control amount of water loss on incubated eggs than windowing. In experiment 3, amount of water loss increased linearly with increasing number of holes on the blunt end of eggshell. Hepatic 3-hydroxy acyl coenzyme A dehydrogenase activity increased with increasing the number of drilled holes.

Repeated recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80, a mast cell degranulator

We examined the recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80 (C48/80), a mast cell degranulator. During the period of 0.5 h to 24 h after treatment with C 48/80 (0.75 mg/kg, i.p.), an apparent recurrence of gastric mucosal lesions was found 18 and 24 h after the lesion formation, progression, and recovery occurred during the period of 12 h. Gastric mucosal blood flow showed the maximum reduction at 0.5, 16, and 22 h after treatment followed by the maximum recovery of the decrease at 12, 20, and 24 h, respectively. Gastric mucosal myeloperoxide and xanthine oxidase activities and lipid peroxide content showed the maximum increase at 3, 18, and 24 h after treatment. Gastric mucosal superoxide dismutase activity unchanged after treatment and gastric mucosal catalase activity decreased only at 24 h. Gastric mucosal Se-glutathione peroxidase activity and vitamin E, ascorbic acid, and hexosamine contents showed their maximum decrease at 3, 18, and 24 h after treatment. Gastric mucosal non-protein SH content showed the maximum decrease at 0.5, 16, and 22 h after treatment. Serum histamine and serotonin concentrations increased rapidly after treatment but the increases in serum histamine and serotonin concentrations diminished completely until 12 and 14 h, respectively. These results indicate that lesions recur repeatedly accompanied with an ischemia-reperfusion-like change in blood flow, inflammation, and disruption of antioxidant defense systems in the gastric mucosa of rats in no relation to released histamine and serotonin after a single C48/80 treatment.

Potential contributions of heat shock proteins to temperature-dependent sex determination in the American alligator

Sex determination in the American alligator depends on the incubation temperature experienced during a thermo-sensitive period (TSP), although sex determination can be 'reversed' by embryonic exposure to an estrogenic compound. Thus, temperature and estrogenic signals play essential roles during temperature-dependent sex determination (TSD). The genetic basis for TSD is poorly understood, although previous studies observed that many of the genes associated with genetic sex determination (GSD) are expressed in species with TSD. Heat shock proteins (HSPs), good candidates because of their temperature-sensitive expression, have not been examined in regard to TSD but HSPs have the ability to modify steroid receptor function. A number of HSP cDNAs (HSP27, DNAJ, HSP40, HSP47, HSP60, HSP70A, HSP70B, HSP70C, HSP75, HSP90alpha, HSP90beta, and HSP108) as well as cold-inducible RNA binding protein (CIRBP) and HSP-binding protein (HSPBP) were cloned, and expression of their mRNA in the gonadal-adrenal-mesonephros complex (GAM) was investigated. Embryonic and neonatal GAMs exhibited mRNA for all of the HSPs examined during and after the TSP. One-month-old GAMs were separated into 3 portions (gonad, adrenal gland, and mesonephros), and sexual dimorphism in the mRNA expression of gonadal HSP27 (male > female), gonadal HSP70A (male < female), and adrenal HSP90 alpha (male > female) was observed. These findings provide new insights on TSD and suggest that further studies examining the role of HSPs during gonadal development are needed.