Structural studies of peri-interactions and bond formation between electron-rich atomic centres and N-phenylcarboxamides or nitroalkenyl groups

Structural studies of peri-interactions with dimethylamino groups in naphthalene systems indicate that the N-phenylcarboxamide group has a through-space electron attracting power closer to that of a carboxylic ester than a N,N-dialkylcarboxamide, while 2-nitroalkenyl groups have a lower through-space electron attracting power. However, addition of a benzoyl group to the 2-position of the nitroethenyl group leads to cyclisation to give a zwitterion, in which the carbanion is stabilised by full conjugation with the nitro group and partial conjugation with the carbonyl group. An interesting case where a steric interaction overrides an electrophile/nucleophile attraction is also described. The limitations to the interpretation of short contact distances from crystallographic measurements are discussed

Yersinia ruckeri isolates recovered from diseased Atlantic Salmon (Salmo salar) in Scotland are more diverse than those from Rainbow Trout (Oncorhynchus mykiss) and represent distinct subpopulations

Yersinia ruckeri is the etiological agent of enteric redmouth (ERM) disease of farmed salmonids. Enteric redmouth disease is traditionally associated with rainbow trout (Oncorhynchus mykiss, Walbaum), but its incidence in Atlantic salmon (Salmo salar) is increasing. Yersinia ruckeri isolates recovered from diseased Atlantic salmon have been poorly characterized, and very little is known about the relationship of the isolates associated with these two species. Phenotypic approaches were used to characterize 109 Y. ruckeri isolates recovered over a 14-year period from infected Atlantic salmon in Scotland; 26 isolates from infected rainbow trout were also characterized. Biotyping, serotyping, and comparison of outer membrane protein profiles identified 19 Y. ruckeri clones associated with Atlantic salmon but only five associated with rainbow trout; none of the Atlantic salmon clones occurred in rainbow trout and vice versa. These findings suggest that distinct subpopulations of Y. ruckeri are associated with each species. A new O serotype (designated O8) was identified in 56 biotype 1 Atlantic salmon isolates and was the most common serotype identified from 2006 to 2011 and in 2014, suggesting an increased prevalence during the time period sampled. Rainbow trout isolates were represented almost exclusively by the same biotype 2, serotype O1 clone that has been responsible for the majority of ERM outbreaks in this species within the United Kingdom since the 1980s. However, the identification of two biotype 2, serotype O8 isolates in rainbow trout suggests that vaccines containing serotypes O1 and O8 should be evaluated in both rainbow trout and Atlantic salmon for application in Scotland

A list of balanced incomplete block designs for r \u3c 30

A balanced incomplete block design consists of a set of v elements arranged into b k-element subsets called blocks such that each element occurs r times and each pair of elements appears in lambda distinct blocks. The numbers v,b,r,k,lambda are called the parameters of the design. A necessary condition that a design exist is that the parameters be integers satisfying: (1) vr = bk ( 2) r(k-1) = lambda (v-1

Fatigue behavior of continuous fiber silicon-carbide-aluminum composites

Four lay-ups of continuous fiber silicon carbide (SCS2) fiber/aluminum matrix composites were tested to assess fatigue mechanisms including stiffness loss when cycled below their respective fatigue limits. The lay-ups were 0 (sub 8), 0(sub 2)/ + or - 45 (sub 2s), 0/90 (sub 2s),and 0/ + or 45/90 (subs). The data were compared with predictions from the author's previously published shakedown model which predicts fatigue-induced stiffness loss in metal matrix composites. A fifth lay-up, + or - 45 (sub 2s), was tested to compare shakedown and fatigue limits. The particular batch of silicon-carbide fibers tested in this program had a somewhat lower modulus (340 GPa) than expected and displayed poor bonding to the aluminum matrix. Good agreement was obtained between the stiffness loss model and the test data. The fatigue damage below the fatigue limit was primarily in the form of matrix cracking. The fatigue limit corresponded to the laminate shakedown for the + or - 45 (sub 2s) laminate

The Relationship Between Student Demographics and Student Engagement with Online Library Instruction Modules

Objective – To investigate whether there are any demographic trends affecting student engagement with online library instruction which might have implications for practice, the authors designed a case study to examine the relationship between student demographic characteristics and engagement with online library instruction modules in English 102 courses at a single university. Methods – The authors recruited 181 students from English 102 (ENG 102), a research-based composition course, to participate in the study. ENG 102 instructors asked all participants to complete an online library instruction module embedded in the university’s course management system, either before in-person library instruction or in lieu of face-to-face library instruction. No external incentive was provided for online module completion. The research team measured levels of student engagement by recording the amount of time students spent on each page of the online module. In collaboration with the Office of Institutional Research, the authors then pulled demographic data on each participant using the university’s student information system. Pearson chi-square tests were performed to determine whether there were any notable associations between levels of student engagement and student age, grade point average, gender, and race/ethnicity. Results – Observable trends tied age and higher grade point average to higher levels of engagement with online instruction. There was additionally a slight trend linking female participants to higher levels of engagement than their male peers. In the category of race/ethnicity, the two largest subgroups, Hispanic and Caucasian students, exhibited similar levels of engagement. Conclusions – The authors conclude that there may be demographic implications for practice in designing online library instruction programs, especially when considering student age and academic performance indicators. They also conclude that, owing to this case study’s limited sample size, further study is warranted to investigate these conclusions, and to further examine the possible impact of gender and race/ethnicity on engagement with online library instruction modules