Resonating valence-bond ground state in a phenalenyl-based neutral radical conductor

An organic material composed of neutral free radicals based on the spirobiphenalenyl system exhibits a room temperature conductivity of 0.3 siemens per centimeter and a high-symmetry crystal structure. It displays the temperature-independent Pauli paramagnetism characteristic of a metal with a magnetic susceptibility that implies a density of states at the Fermi level of 15.5 states per electron volt per mole. Extended Hückel calculations indicate that the solid is a three-dimensional organic metal with a band width of approximately 0.5 electron volts. However, the compound shows activated conductivity (activation energy, 0.054 electron volts) and an optical energy gap of 0.34 electron volts. We argue that these apparently contradictory properties are best resolved in terms of the resonating valence-bond ground state originally suggested by Pauling, but with the modifications introduced by Anderson.     

Isolation and identification of canine adenovirus type-2 from the upper respiratory tract of a dog

AIM: To report on the isolation and identification of canine adenovirus type-2 (CAV-2) from a greyhound dog with tracheitis/tonsillitis. METHODS: Virus isolation was performed with Madin and Darby canine kidney (MDCK) cell monolayers using standard virological techniques. The isolated virus was identified by haemagglutination inhibition and serum neutralisation tests. Viral DNA was extracted from infected MDCK cells and subjected to restriction endonuclease analysis using the endonuclease enzymes Bam HI, Bgl II, Eco RI and Hind III. RESULTS: A virus, designated 5 113-87, was isolated in MDCK cells yielding typical cytopathic effect. The virus could be neutralised with a CAV-2 specific reference antiserum and also showed some cross neutralisation with CAV-1 specific reference antiserum. The virus 5 113-87 had a high haemagglutination inhibition titre with CAV-2 antiserum using human group 0 red blood-cells and CAV-1 and CAV-2 reference antisera. This virus also had DNA restriction profiles identical to those of the reference CAV-2 (Toronto A26/61), whereas previously isolated strains of adenovirus from dogs in New Zealand had DNA restriction patterns identical to the prototype CAV-1 strain (Utrecht). CONCLUSION: The findings show that the virus 5 113-87 isolated from the upper respiratory tract of a dog in New Zealand is CAV-2.     

Zoogeographical barriers causing discontinuous osteometrical variations in the northern treeshrew skulls

Morphological variation of the skull was examined in the northern treeshrew (Tupaia belangeri) from various localities across Southeast Asia. Through a multivariate analysis, the treeshrews from South Vietnam exhibited distinct morphological characteristics compared to other populations from Thailand and Laos, and Malaysia. The plots of the specimens of North Vietnam are not randomly mixed with Thailand plots segregation in the scatteregrams of canonical discriminant analysis. Since the skulls of the population from North Vietnam were morphologically similar to those form central Laos and northern and northeastern Thailand, the zoogeographical barrier effect of Mekong River was not clearly confirmed. The population of the Kanchanaburi in western Thailand is clearly smaller in size compared to the other populations. The southern border of the distribution of this species is determined by the Isthmus of Kra or Kangar-Pattani Line. In the northern treeshrew, which is distributed from southern China to Bangladesh and southern Thailand, we have detected osteometrical geographical variation driven by geography. These results indicate that the skull morphology in the Tupaia glis-belangeri complex distinctively differs in South Vietnam, western Thailand, and southern Thailand. The zoogeographical barrier and factor separating these districts are expected to clarify in the future.     

Prevalence and radiologic and histologic appearance of vesicourachal diverticula in dogs without clinical signs of urinary tract disease

OBJECTIVE: To determine prevalence and radiologic and histologic appearance of vesicourachal diverticula in dogs without clinical signs of urinary tract disease. DESIGN: Original study. ANIMALS: 50 dogs between 4 months and 17 years old representing 22 breeds that had been euthanatized for unrelated reasons; none of the dogs had a history or clinical signs of urinary tract disease. PROCEDURE: Retrograde positive-contrast radiography was performed, and radiographs were examined for macroscopic diverticula. Necropsy specimens from the urinary bladder vertex were examined by means of light microscopy for diverticula and signs of inflammation. RESULTS: 17 of the 50 (34%) dogs had vesicourachal diverticula, and 1 additional dog had a urachal cyst. Fifteen of the 17 diverticula were macroscopic; surface area of the diverticulum could be measured radiographically in 13 of these dogs and ranged from 1 to 90 mm2. The remaining 2 diverticula were microscopic. Sixteen diverticula were intramural and 1 was extramural. Light microscopic signs of bladder wall inflammation could be detected in 5 dogs, 4 of which had macroscopic diverticula. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a high percentage of dogs without clinical signs of urinary tract disease may have vesicourachal [corrected] diverticula. Further studies are needed to determine the clinical relevance of vesicourethral diverticula in dogs.     

Polycyclic Aromatic Hydrocarbons (PAHs) in the Aerosol of Higashi Hiroshima, Japan: Pollution Scenario and Source Identification

Polycyclic aromatic hydrocarbons (PAHs) are considered to be atmospheric pollutants and well-known human carcinogens. This study analyzes the pollution scenarios of PAHs in the aerosol of Higashi Hiroshima, Japan. We examined the characteristics, the influences of meteorological conditions, the distribution and seasonal variation of PAHs in aerosol samples collected from June 2000 to May 2001. The concentration of PAHs in the aerosol of Higashi Hiroshima was ranging from 11.8 to 157.5 μg/g with a mean concentration of 63.4 μg/g. Results showed that there is positive correlation between aerosol PAH concentrations and ambient temperature but a relatively little correlation with solar radiation. Seasonal variation was observed with a higher concentration during winter and lower concentration during summer. Apart from that, principal component analysis and molecular diagnostic ratios were also used to characterize and identify possible PAHs emission sources. Results obtained strongly suggested that vehicular emissions appeared to be the major source of aerosol PAHs in this study although other sources do have some degree of influence.