Imaging surface atomic structure by means of auger electrons

Measurements of the complete angular distribution of Auger electrons emitted from well-defined platinum[111] single-crystal surfaces have led to the discovery that the distributions are composed of "silhouettes" of surface atoms "back lit" by emission from atoms deeper in the solid. Theoretical simulations of Auger electron angular distributions based upon atomic point emitters and spherical atomic scatterers of uniform cross section are in close agreement with these experimental results, but opposite to previous theoretical predictions. In view of the definitive results obtained and the straightforward agreement between theory and experiment, angular distribution Auger microscopy (ADAM) is useful for direct imaging of interfacial structure and investigation of electron-solid interactions in the physical and biological sciences and engineering. Applicability of ADAM is illustrated by images obtained for monolayers of silver and iodine on platinum[111].     

Clinical characteristics, treatment, and outcome of dogs with presumed primary hepatic lymphoma: 18 cases (1992-2008)

OBJECTIVE-To determine outcome of dogs with presumed primary hepatic lymphoma treated with various multiagent, doxorubicin-based chemotherapeutic protocols and identify factors associated with prognosis. DESIGN-Retrospective case series. ANIMALS-18 dogs with presumed primary hepatic lymphoma. PROCEDURES-Medical records were reviewed for information on signalment, treatment, and outcome. RESULTS-8 dogs had a complete remission (CR), with a median remission duration of 120 days. Dogs with leukocytosis, neutrophilia, hypoalbuminemia, hyperbilirubinemia, or a combination of hypoalbuminemia and hyperbilirubinemia were less likely to achieve a CR. Overall median survival time (MST) was 63 days (range, 2 to 402 days). In a multivariate analysis, response to treatment and serum albumin concentration were associated with MST. Dogs that did not achieve a CR had a significantly shorter MST than did dogs that did achieve a CR (13 vs 283 days, respectively). Dogs with serum albumin concentration < 2.5 g/dL at the time treatment was initiated had a significantly shorter MST than did dogs with serum albumin concentration within reference limits (10 vs 128 days, respectively). There was also a positive correlation between serum albumin concentration and survival time (r = 0.74). CONCLUSIONS AND CLINICAL RELEVANCE-Results suggested that dogs with primary hepatic lymphoma that underwent chemotherapy had a poor prognosis, with a low response rate. Dogs that responded to treatment had a better prognosis, and dogs with hypoalbuminemia had a poorer prognosis.     

Reaction of chlorine nitrate with hydrogen chloride and water at antarctic stratospheric temperatures

Laboratory studies of heterogeneous reactions important for ozone depletion over Antarctica are reported. The reaction of chlorine nitrate (ClONO(2)) with H(2)0 and hydrogen chloride (HCl) on surfaces that simulate polar stratospheric clouds [ice and nitric acid (HNO(3))-ice and sulfuric acid] are studied at temperatures relevant to the Antarctic stratosphere. The reaction of ClONO(2) on ice and certain mixtures of HNO(3) and ice proceeded readily. The sticking coefficient of ClONO(2) on ice of 0.009 +/- 0.002 was observed. A reaction produced gas-phase hypochlorous acid (HOCl) and condensed-phase HNO(3); HOC1 underwent a secondary reaction on ice producing dichlorine monoxide (Cl(2)O). In addition to the reaction with H(2)0, ClONO(2) reacted with HCl on ice to form gas-phase chlorine (Cl(2)) and condensed-phase HNO(3.) Essentially all of the HCl in the bulk of the ice can react with ClONO(2) on the ice surface. The gaseous products of the above reactions, HOCl, Cl(2)0, and Cl(2), could readily photolyze in the Antarctic spring to produce active chlorine for ozone depletion. Furthermore, the formation of condensed-phase HNO(3) could serve as a sink for odd nitrogen species that would otherwise scavenge the active chlorine.     

Genome rearrangement and nitrogen fixation in Anabaena blocked by inactivation of xisA gene

Two genome rearrangements involving 11- and 55-kilobase DNA elements occur during the terminal differentiation of an Anabaena photosynthetic vegetative cell into a nitrogen-fixing heterocyst. The xisA gene, located on the nifD 11-kilobase DNA element, was inactivated by recombination between the chromosome and a copy of the xisA gene that was mutated by inserting an antibiotic gene cassette. Site-directed inactivation of the Anabaena xisA gene blocked rearrangement of the 11-kilobase element and nitrogen fixation, but did not affect rearrangement of the 55-kilobase element, heterocyst differentiation, or heterocyst pattern formation.     

The relationships among mitochondrial uncoupling protein 2 and 3 expression, mitochondrial deoxyribonucleic acid single nucleotide polymorphisms, and residual feed intake in Angus steers

The objective of this study was to determine the relationships of uncoupling protein 2 and 3 expression, SNP of mitochondrial DNA, and residual feed intake (RFI) in Angus steers selected to have high or low RFI. Individual feed intake was measured via the GrowSafe feed intake system over a 3-mo period and used to calculate RFI, a measure of efficiency. Based on these calculations, 6 low- (average RFI = -1.57 kg) and 6 high- (average RFI = 1.66 kg) RFI steers were selected for further study. Blood was collected via jugular venipuncture 1 wk before slaughter for the isolation of mitochondrial DNA. The steers were then killed to collect LM for the measurement of uncoupling protein 2 and 3 mRNA and protein expression. Protein and mRNA expression of uncoupling protein 2 and 3 were determined by Western blotting and quantitative PCR, respectively. To determine SNP of mitochondrial DNA, total DNA was isolated from blood via standard phenol/chloroform extraction; fragments were amplified with PCR and sequenced with an automated nucleotide sequencer. Average daily gain and carcass composition were not different (P > 0.13) between the high- and low-RFI steers; however, ADFI by the high-RFI animals was 3.77 kg greater (P < 0.001) than the low-RFI animals. No difference (P > 0.55) was observed between the high- and low-RFI animals in their expression of uncoupling protein 2 or 3 mRNA or protein. On average 9.8 and 8.9 polymorphisms were found per mitochondrial genome for the low- and high-RFI steers, respectively. None of these polymorphisms were related to RFI. It seems that the expression of uncoupling protein 2 and 3 and mitochondrial DNA sequence are not related to RFI status.