Hydrogen storage in microporous metal-organic frameworks

Metal-organic framework-5 (MOF-5) of composition Zn4O(BDC)3 (BDC = 1,4-benzenedicarboxylate) with a cubic three-dimensional extended porous structure adsorbed hydrogen up to 4.5 weight percent (17.2 hydrogen molecules per formula unit) at 78 kelvin and 1.0 weight percent at room temperature and pressure of 20 bar. Inelastic neutron scattering spectroscopy of the rotational transitions of the adsorbed hydrogen molecules indicates the presence of two well-defined binding sites (termed I and II), which we associate with hydrogen binding to zinc and the BDC linker, respectively. Preliminary studies on topologically similar isoreticular metal-organic framework-6 and -8 (IRMOF-6 and -8) having cyclobutylbenzene and naphthalene linkers, respectively, gave approximately double and quadruple (2.0 weight percent) the uptake found for MOF-5 at room temperature and 10 bar.     

Genetic diversity of American hazelnut in the Upper Midwest,USA

World hazelnut production is based on European hazelnut (Corylus avellana) and is limited by the narrow climatic requirements of this species. The cold hardiness and disease resistance of the American hazelnut (Corylus americana) offer opportunities to expand production to new areas including the Upper Midwest (USA). The American hazelnut is a phenotypically diverse species. This study used ten microsatellite marker loci to investigate genetic diversity in 1140 individuals sampled from 25 populations across Wisconsin, Iowa, Minnesota and North Dakota. Overall, the marker loci were highly polymorphic (H_o = 0.69, H_e = 0.78, PIC = 0.84) with 7–13 alleles per locus. There was very high genetic diversity within populations (90% of the total) and some tendency toward population differentiation. Mantel’s test showed that genetic distance among the populations was not correlated with geographic distance. We conclude that selection of individuals for use in breeding should be based primarily on phenotype (productivity, nut size, percent kernel, ease of harvest), with care to include representatives of genetically differentiated populations.     

A single drought event of 100‐year recurrence enhances subsequent carbon uptake and changes carbon allocation in experimental grassland communities

Evidence suggests that the expected increase in frequency and magnitude of extreme weather events during climate change will alter plant productivity. Therefore, extreme weather events might also be capable of changing C sequestration and allocation. Here, experimental grassland communities of two species compositions, differing in their diversity, were exposed either to a simulated single drought or to a heavy‐rainfall event. The magnitude of these manipulations imitated the local 100‐year weather extreme according to extreme‐value statistics. Effects on Net Ecosystem CO₂ Exchange (NEE in µmol m^–2 s^–1) as well as aboveground biomass production and leaf‐area index (LAI) were recorded from prior to the manipulations until two months after the manipulations ended. Initial light utilization efficiency and maximum NEE increased after the drought. No change in the respiration was detected and maximum uptake capacity (GPP_max) was 15% higher for the drought‐manipulated plots compared to controls, which indicates an enhanced CO₂ uptake into the systems. The level of diversity was also found to alter the light‐response curves, increasing respiration and maximum NEE to a higher degree than drought in the more diverse compared to the less diverse community. This resulted in an increase of GPP_max by 55%. No significant interactions between species composition and weather manipulations were detected. Interestingly, aboveground biomass production was not significantly affected by weather manipulations, even though LAI increased due to drought. This increase was caused by a decrease in the ratio between reproductive and vegetative growth. The heavy‐rainfall manipulation resulted in no significant effects. Our data suggest that C sequestration can be enhanced by a single weather event. However the importance, long‐term duration, and thresholds or turning points of such effects need to be investigated further as intensification of weather extremes is currently emerging as one of the most important facets of climate change.     

Crown thinning on Eucalyptus dunnii stands for saw- and veneer logs in southern Brazil

New Forests - Eucalypt plantations occupy >?5 million ha in the warm regions of Brazil. In the southern highlands, however, forestry is dominated by Pinus taeda. The frost-tolerant...     

Orbital neoplasia in 23 dogs

Medical records of 23 dogs with histologically documented orbital neoplasia and admitted to the New York State College of Veterinary Medicine between 1975 and 1984 were reviewed. Almost all (91%) of the tumors were classified as malignant; 74% of the tumors arose as primary neoplasms within the orbit. Eleven tumor types of connective tissue, bone, epithelial, and hemolymphatic origin were represented. The typically afflicted dog was purebred, female, and middle-aged. Review of this series confirmed the clinical impression that orbital neoplasms in dogs are aggressive malignancies with poor long-term prognosis.     

Comparison of trochlear block recession and trochlear wedge recession for canine patellar luxation using a cadaver model

OBJECTIVE: To compare trochlear block recession (TBR) to trochlear wedge recession (TWR) with regards to patellar depth (percentage of patellar volume under the trochlear ridges), patellar articular contact, percentage of recessed trochlear surface area, and resistance to patellar luxation. STUDY DESIGN: In vitro computed tomography (CT) and biomechanical evaluation using a cadaver model. SAMPLE POPULATION: Twelve normal, large-breed canine cadavers. METHODS: Bilateral pelvic limb specimens with intact stifle joints were mounted on a positioning device. The femoral trochlear ridges were reduced to provide a standard shallow trochlea. TBR or TWR was performed to a standard depth randomly on paired specimens. CT and biomechanical evaluations were performed pre- and postoperatively in both an extended (148 degrees ) and flexed (113 degrees ) stifle position. CT images were digitized and measurements made using an image-analysis software program. Biomechanical testing consisted of applying 40 degrees of internal tibial rotation and documenting patellar luxation. RESULTS: The change in trochlear depth (depth of recession) was not significantly different between groups. In the extended stifle position (patella in the proximal trochlea), patellar depth and patellar articular contact with the recessed trochlea were significantly greater after TBR compared with TWR. The percentage of recessed trochlear surface area was significantly greater after TBR compared with TWR. In the extended position, a smaller percentage of the patellae luxated within 40 degrees of internal tibial rotation after TBR compared with TWR. CONCLUSIONS: TBR increases proximal patellar depth, increases patellar articular contact with the recessed proximal trochlea, recesses a larger percentage of trochlear surface area, and results in a greater resistance to patellar luxation in an extended position as compared with TWR. CLINICAL RELEVANCE: TBR may help limit the development of stifle DJD in dogs treated for canine patellar luxation.     

Thyroid cystadenoma, colloid goiter, and hypothyroidism in an American black bear (Ursus americanus).

A 178-kg, 14-yr-old captive female American black bear (Ursus americanus) was examined because of lethargy, inappetance, obesity, and alopecia. Serum chemistry and complete blood count values were within normal limits. Based on serum levels for total thyroxine (T4), free T4 by equilibrium dialysis (fT4ED), and canine thyroid-stimulating hormone concentrations, using assays validated for domestic dogs, hypothyroidism was diagnosed presumptively, and therapy with levothyroxine sodium (0.022 mg/kg p.o. b.i.d.) was initiated. Haircoat, body weight, appetite, and activity level improved within 30 days. The levothyroxine dose was decreased twice (to 0.018 mg/kg p.o. b.i.d. and then to 0.011 mg/kg p.o. b.i.d.) during the course of treatment based on monitoring of serum T4 and fT4ED concentrations. After euthanasia for severe refractory lameness, postmortem examination revealed bilateral thyroid lobe enlargement and a fluid-filled cyst within the right lobe. Histologically, colloid goiter was present in both lobes, and a follicular cystadenoma had replaced one third of the cranial pole of the right lobe. The goiter and cystadenoma likely contributed to the hypothyroid condition in this bear and fT4ED was a more sensitive indicator of hypothyroidism than was T4. The recommended canine dosage of levothyroxine may be too high for the treatment of hypothyroidism in American black bears; 0.011 mg/kg p.o. b.i.d. may be a more appropriate dosage.     

Antibacterial agents for ocular therapeutics.

Ocular bacterial infections of animals take a variety of forms. The eyelid, external ocular surface, anterior segment, posterior segment,and orbit are all frequent targets. Effective management of ocular bacterial infections requires specific identification of the offending organism(s) combined with knowledge of the mechanisms of action and the therapeutic characteristics of available antibiotics.