Atomically defined interfaces that maximize the density of active sites and harness the electronic metal−support interaction are desirable to facilitate challenging multielectron transformations, but their synthesis remains a considerable challenge. We report the rational synthesis of the atomically defined metal chalcogenide nanopropeller Fe 3 Co 6 Se 8 L 6 (L = Ph 2 PNTol) featuring three Fe edge sites, and its ensuing catalytic activity for carbodiimide formation. The complex interaction between the Fe edges and Co 6 Se 8 support, including the interplay between oxidation state, substrate coordination, and metal−support interaction, is probed in detail using chemical and electrochemical methods, extensive single crystal X-ray diffraction, and electronic absorption and Mossbauer spectroscopy.

Because of the high prevalence of penicillinase-producing Neisseria gonorrhoeae in the Republic of Korea, spectinomycin has been used there in the primary treatment of gonococcal infections in U.S. military personnel since 1981, but there have been increasingly frequent reports of treatment failures with spectinomycin. We conducted a clinical study to determine the efficacy of spectinomycin treatment in 124 U.S. servicemen in the Republic of Korea who had urethral gonococcal infections. Ninety-seven patients were treated with spectinomycin alone and evaluated in a follow-up visit. In eight patients (8.2 percent), this treatment was unsuccessful. Antibiotic-sensitivity testing on isolates from seven of the patients with treatment failure demonstrated that six isolates were highly resistant to spectinomycin (minimal inhibitory concentration, greater than or equal to 100 micrograms per milliliter). None of the spectinomycin-resistant strains had become resistant to penicillin, either through the production of penicillinase or through a chromosomal mutation. Although the mechanism of spectinomycin resistance appears to be a chromosomal mutation, these isolates were generally sensitive to other antibiotics. The prevalence of resistance to spectinomycin resulted in the substitution of ceftriaxone for the primary treatment of gonorrhea acquired by U.S. military personnel in the Republic of Korea. We believe that the rapid emergence of spectinomycin resistance in this population mandates a cautious approach to widescale use of the drug and indicates a need to broaden current surveillance programs.

This study provides atomistic insights into the interface between a single-site catalyst and a transition metal chalcogenide support and reveals that peak catalytic activity occurs when edge/ support redox cooperativity is maximized. A molecular platform MCo 6 Se 8 (PEt 3 ) 4 (L) 2 (1-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (Co 6 Se 8 ) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal 1-M clusters display remarkable catalytic activity for coupling tosyl azide and tert-butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series. Structural, electronic, and magnetic characterization of the clusters was performed using single crystal X-ray diffraction, 1 H and 31 P nuclear magnetic resonance spectroscopy, electronic absorption spectroscopy, cyclic voltammetry, and computational methods. Distinct metal/support redox regimes can be accessed in 1-M based on the energy of the edge metal's frontier orbitals with respect to those of the cluster support. As the degree of electronic interaction between the edge and the support increases, a cooperative regime is reached wherein the support can deliver electrons to the catalytic site, increasing the reactivity of key metal-nitrenoid intermediates.

The authors identified hospitalizations for pneumonia (n = 6,522) in active-duty Navy and Marine Corps personnel during 1981-1991 from computerized inpatient records. The crude mean annual rate of pneumonia hospitalization was 77.6 per 100,000 active-duty personnel; 65% of pneumonia hospitalizations had no etiologic agent identified. The most commonly reported agents to cause pneumonia hospitalization were Streptococcus pneumoniae (12.3%), Mycoplasma pneumoniae (10.8%), other streptococcal species (2.1%), and Haemophilus influenzae (1.9%). The median age at hospitalization was 22 years. The median duration of hospital stay was 4 days and the case fatality rate was 0.4%. The authors used a 2% sample of the entire population and by means of stepwise unconditional multivariate logistic regression modeling for pneumonia found that, independent of age, the most junior Navy and Marine Corps personnel were at highest risk. Whites were at higher risk than blacks, Hispanics, or Filipinos. These results indicate that among this generally healthy US young adult military population, pneumonia hospitalization is common, often brief, and frequently without specifically identified pathogens.

We demonstrate that allosteric effects and redox state changes can be harnessed to create a switch that selectively and reversibly regulates the coordination chemistry of a single site on the surface of a molecular cluster. This redox-switchable allostery is employed as a guiding force to assemble the molecular clusters Zn 3 Co 6 Se 8 L′ 6 (L′ = Ph 2 PN(H)Tol, Ph = phenyl, Tol = 4-tolyl) into materials of predetermined dimensionality (1- or 2-D) and to encode them with emissive properties. This work paves the path to program the assembly and function of inorganic clusters into stimuli-responsive, atomically precise materials.