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ABSTRACTThe prevalence, among human clinical cases, of Salmonella entericaserotype 4,5,12:i:-, a serotype antigenically similar to Salmonella entericaserotype Typhimurium but lacking second-phase flagellar antigens, has increased considerably over the last 10 years. To probe the evolution and ecology of this emerging serotype, we characterized 190 Salmonellaisolates initially classified as Salmonellaserotypes 4,5,12:i:- (n= 90) and Typhimurium (n= 100) and obtained from various sources in the United States and Spain. These isolates were characterized into six sequence types (determined by multilocus sequence typing [MLST]) and 79 pulsed-field gel electrophoresis types. The majority of Salmonellaserotype 4,5,12:i:- and Typhimurium isolates (85 and 84 isolates, respectively) represented a single MLST type. Existing genome information revealed different genome deletions (which included genes responsible for phase 2 flagellum expression) in four Spanish Salmonellaserotype 4,5,12:i:- isolates and one U.S. Salmonellaserotype 4,5,12:i:- isolate. Fifty-nine isolates of both serotypes, representing different sources and geographical locations as well as different molecular subtypes, were thus screened for the presence of six genes and one specific region, all of which were previously found to show variable presence among Salmonellaserotype 4,5,12:i:- and Typhimurium strains. All Salmonellaserotype 4,5,12:i:- isolates lacked the phase 2 flagella genes fljAand fljB, which were present in all Salmonellaserotype Typhimurium isolates. While all Spanish Salmonellaserotype 4,5,12:i:- isolates carried the same deletion surrounding fljAB, all but two U.S. isolates showed a different genomic deletion; the two atypical U.S. isolates represented the “Spanish” deletion genotype and a unique deletion genotype. Salmonellaserotype 4,5,12:i:- thus appears to represent at least two common clones, which cannot easily be differentiated with standard diagnostic procedures.

Natural-abundance ¹⁵N nuclear magnetic resonance (NMR) experiments show direct evidence for metal−pyridine interactions in blends of pyridine-containing polyurethanes and metal acetates. After blending with zinc acetate, the pyridine nitrogen peak shifts from −320 to −304 ppm; blending with magnesium acetate causes a shift to −309 ppm. Sodium acetate did not complex with the pyridine-containing polyurethanes; no shifts in the ¹³C NMR signal for the acetate carbonyl or in the ¹⁵N NMR for the pyridine nitrogen are apparent. Additionally, no interactions were evident for the urethane nitrogen site in any of the blends. Peak shifts, changes in cross-polarization dynamics, and increases in relaxation times were also apparent in the ¹³C NMR spectra of the metal acetate−polymer blends. Effects of blending on the hard-domain hydrogen bonding were evident in FTIR and ¹⁵N NMR contact-time experiments. The N−H stretching band shifted to higher wavenumbers and the ¹⁵N NMR N−H signal persisted to longer contact times for the blend. Both spectroscopic techniques give evidence for complexation in these polyurethane blends.

Ion content and molecular weight have been shown to affect the ²³Na NMR spectra of monodisperse sodium-neutralized sulfonated polystyrene ionomers (MNaSPS). A new NMR peak at −2.7 ppm appears at ionization levels above 1.2% and molecular weights of a least 35 000; this peak is not present in polydisperse NaSPS. The fraction of NMR intensity due to this peak is relatively constant above Mn ~ 100 000. It is proposed that this peak is due to a distorted version of an isolated site. Along with the new −2.7 ppm peak, the monodisperse materials also have far fewer isolated ions than the corresponding polydisperse ionomers. It is possible that the greater chain uniformity of the monodisperse ionomers eliminates plasticization of the aggregates by the low molecular weight components and steric hindrances from the high molecular weight components and permits more complete aggregation of the ionic groups. The new NMR peak can be removed by casting from a cosolvent of THF/water, but not by casting from THF/methanol. Blending of two or more monodisperse materials in solution followed by annealing resulted in an NMR spectrum similar to that of a polydisperse material; however, the behavior of the blend without annealing did not replicate that of polydisperse NaSPS.

Gastrointestinal disorders of varying severity were observed in 239 (53%) of 455 campers and staff members at a coed summer camp in Sullivan County, New York, during July 1981. Five of seven hospitalized patients had appendectomies before the disease was recognized as yersiniosis. Yersinia enterocolitica serogroup O:8 (American strain) was isolated from 37 (54%) of 69 persons examined, including the head cook and 3 others of the 11-person kitchen staff. Of 48 food, water, and environmental samples collected from the camp area, Y. enterocolitica isolates belonging to the same serogroup and biogroup as the human isolates were recovered from dissolved powdered milk, a milk dispenser, and turkey chow mein. This laboratory finding supported the epidemiological data indicating a correlation between consumption of these foods and illness. Y. enterocolitica isolates of the same biogroup as the O:8 isolates but belonging to serogroup O:34 were also isolated from six campers and two samples of dissolved powdered milk. Pathogenicity studies on the Yersinia isolates were performed with three in vitro tests (calcium dependency, autoagglutination, and HeLa cell infection) and one in vivo test (intraperitoneal challenge of mice). Most of the serogroup O:8 human isolates and the chow mein isolate were positive in all four tests. Milk isolates of serogroup O:8 were positive in the in vitro tests but were relatively avirulent in mice, whereas serogroup O:34 isolates, regardless of source, were negative in all four tests.

Diffusivities of several proteins or protein variants in nonadsorbing rigid-polymer and bonded-phase-silica chromatographic media were determined using pulsed-field-gradient NMR of both proton and fluorine nuclei. Solute size, pore size, and concentration all affect the intraparticle diffusivity. The intraparticle diffusivity of proteins is well represented by a hindered diffusion of a sphere in a long cylinder and a tortuosity factor of 2.0 for a ratio of solute diameter to pore diameter ranging from 0 to 0.3. An investigation of the effects of fluorine labeling on protein chemistry and hydrodynamics revealed that the extensive fluorine labeling denatured the protein, increasing its effective Stokes radius. The fluorine labeling did not, however, significantly alter the intraparticle diffusivity variation dependence on protein and pore sizes.

During a 4-year period, 4,448 human, animal, and environmental samples collected in New York State were tested for the presence of Yersinia enterocolitica or related species. A total of 339 isolates were identified as Yersinia and characterized according to source, species, biogroup, serogroup, and, in some instances, phage type. Four new biogroups of Y. intermedia were characterized. Of 149 human isolates, 120 (80.5%) were identified as Y. enterocolitica, and 29 were identified as either Y. intermedia (12.1%), Y. frederiksenii (5.4%), or Y. kristensenii (2.0%). Of the other 190 isolates, recovered from animals and the environment, 54 (28.4%) were Y. enterocolitica and 136 were either Y. intermedia (62.6%), Y. frederiksenii (4.7%), Y. kristensenii (3.7%), or an undescribed Yersinia species (0.5%). Two established human pathogenic strains of Y. enterocolitica were recovered: 59 isolates (37 from an outbreak) of "American strain" (serogroup O:8, biogroups Niléhn 2, Wauters 1, and Knapp and Thal 2, phage type Xz) and 11 isolates of "Canadian strain" (serogroup O:3, biogroups Niléhn 4, Wauters 4, and Knapp and Thal 1, phage types IXb). This was the first documented isolation of the Canadian strain in the United States. Isolates of other strains implicated in human disease (serogroups 0:4,33, 0:5, O:6,31, O:7,8, and O:8) were also recovered from both human and nonhuman sources.

Presented below is a method of calculating the off-design performance of multistage axial compressor characteristics that differs in concept from previous methods. A set of resulting calculations has certain general properties; namely, that it is independent of absolute stage work and flow coefficient, number of stages, and annulus geometry. The set depends only on a stage characteristic “shape” which is normalized so that the work and pressure coefficient is unity when the flow coefficient is unity. One set of tabulated results can be applied to many different designs. Two comparisons with experiment are presented below and the agreement is fairly good. An added benefit derived from this kind of general approach is that one gains physical understanding of the various regions of compressor operation. In this regard the concepts of “axial equilibrium” and “match point” have been developed which in the present context are defined in a precise, quantitative manner.

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The article offers information on the educational video 'Water Style for Beginners' by Helen Liang.

The article presents views of several readers of the journal on issues related to U.S. Armed Forces including reserve soldiers, cyberwar and troops committing suicide.