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In order to expand our understanding of a potential zinc-based battery electrolyte, we have characterized the physical and transport properties of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) containing various levels of both Zn(2+) and H2O. Detailed measurements of density, viscosity, conductivity, and individual anion and cation diffusion coefficients using pulsed-field-gradient (PFG) NMR combined with NMR chemical shifts and spin-lattice relaxation (T1) NMR experiments provide insights into the motion and chemical environment of all molecular species. We find that the various techniques for probing ion transport and dynamics form a coherent picture as a function of electrolyte composition. Zn(2+) addition causes a moderate reduction in the self-diffusion of the IL anion and cation, whereas the addition of H2O increases ion mobility by increasing the liquid's overall fluidity. Temperature-dependent (13)C T1 experiments of the dca carbon analyzed using Bloembergen-Purcell-Pound fits show monotonic slowing of anion dynamics with Zn(2+) addition, suggesting increased Zn(2+)/dca(-) association. T1 experiments show minimal change in the spin-lattice relaxation of cation or anion upon H2O addition, suggesting that H2O is playing no significant role in Zn(2+) speciation. Finally, we employ a novel electrophoretic NMR technique to directly determine the electrophoretic mobility of the C4mpyr cation, which we discuss in the context of impedance-based conductivity measurements.

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The unusual exhibition of a biaxial nematic phase in nonlinear thermotropic mesogens derived from the 2,5-oxadiazole biphenol (ODBP) core is placed in a general context; the uniaxial nematic phase of the prototypical rod-like mesogen para-quinquephenyl does not follow the classical mean-field behaviour of nematics, thus questioning the utility of such theories for quantitative predictions about biaxial nematics. The nuclear magnetic resonance spectra of labelled probe molecules dissolved in ODBP biaxial nematic phases suggest that a second critical rotation frequency, related to the differences in the transverse diamagnetic susceptibilities of the biaxial nematic, must be exceeded in order to create an aligned two-dimensional powder sample. Efforts to find higher viscosity and lower temperature biaxial nematics (with lower critical rotation rates) to confirm the above conjecture are described. Several chemical modifications of the ODBP mesogenic core are presented.

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We report the experimental realization of BOOMERANG (better observation of magnetization, enhanced resolution, and no gradient), a sensitive and general method of magnetic resonance. The prototype millimeter-scale NMR spectrometer shows signal and noise levels in agreement with the design principles. We present 1H and 19F NMR in both solid and liquid samples, including time-domain Fourier transform NMR spectroscopy, multiple-pulse echoes, and heteronuclear J spectroscopy. By measuring a 1H-19F J coupling, this last experiment accomplishes chemically specific spectroscopy with force-detected NMR. In BOOMERANG, an assembly of permanent magnets provides a homogeneous field throughout the sample, while a harmonically suspended part of the assembly, a detector, is mechanically driven by spin-dependent forces. By placing the sample in a homogeneous field, signal dephasing by diffusion in a field gradient is made negligible, enabling application to liquids, in contrast to other force-detection methods. The design appears readily scalable to microm-scale samples where it should have sensitivity advantages over inductive detection with microcoils and where it holds great promise for application of magnetic resonance in biology, chemistry, physics, and surface science. We briefly discuss extensions of the BOOMERANG method to the microm and nm scales.

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We have synthesized liquid crystal (LC) mesogens based on a nonlinear oxadiazole unit that exhibit nematic phases near 200 degrees C. Polarized microscopy and conoscopy indicate that these LCs are biaxial nematics. Unambiguous and quantitative evidence for biaxiality is achieved using 2H NMR spectroscopy. "2D powder" spectra, obtained by rotating 2H-labeled samples about an axis perpendicular to the magnetic field at approximately 200 Hz, yield phase biaxiality parameters of approximately 0.1 when coupled with rigorous and proven simulations.

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A novel method of nuclear magnetic resonance (NMR) is described which promises to be preferable to known general methods at sample length scales below approximately 100 microm. Its advantages stem from the seemingly paradoxical combination of a homogeneous static magnetic field and detection of a mechanical force between a spin-bearing sample and a magnet assembly. In contrast to other methods of force-detected nuclear magnetic resonance (FDNMR), the method is characterized by better observation of magnetization, enhanced resolution, and no gradient (BOOMERANG), and it is generally applicable with respect to sample composition, pulse sequence, and magnetic field strength. Further advantages of portability and low cost stem from the small instrument volume and mass and promise to extend the use of NMR to new applications and environments. A sensitivity analysis, relevant to spectroscopy or imaging, quantifies the advantage of BOOMERANG relative to magnetic induction using microcoils and to FDNMR methods that rely on large gradients of the magnetic field at the sample.

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BACKGROUND AND METHODS: The frequency of infection with multidrug-resistant Mycobacterium tuberculosis is increasing. We reviewed the clinical courses of 171 patients with pulmonary disease due to M. tuberculosis resistant to rifampin and isoniazid who were referred to our hospital between 1973 and 1983. The patients' records were analyzed retrospectively. Their regimens were selected individually and preferably included three medications that they had not been given previously and to which the strain was fully susceptible. RESULTS: The 171 patients (median age, 46 years) had previously received a median of six drugs and shed bacilli that were resistant to a median of six drugs. Thus, their regimens were frequently not optimal. Of 134 patients with sufficient follow-up data, 87 (65 percent) responded to chemotherapy (as indicated by negative sputum cultures for at least three consecutive months); 47 patients (35 percent) had no response, as shown by continually positive cultures. The median stay in the hospital was more than seven months. In a multivariate analysis, an unfavorable response was significantly associated with a greater number of drugs received before the current course of therapy (odds ratio, 4.0; 95 percent confidence interval, 1.6 to 9.9; P < 0.001) and with male sex (odds ratio, 2.5; 95 percent confidence interval, 1.1 to 6.2; P < 0.03). Twelve of the patients with responses subsequently had relapses. The overall response rate was 56 percent over a mean period of 51 months. Of the 171 patients, 63 (37 percent) died, and 37 of these deaths were attributed to tuberculosis. CONCLUSIONS: For patients with pulmonary tuberculosis that is resistant to rifampin and isoniazid, even the best available treatment is often unsuccessful. Only about half of such patients eventually have negative sputum cultures despite carefully selected regimens administered for extended periods. Failure to control this resistant infection is associated with high mortality and ominous implications for the public health.

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Artificial pneumoperitoneum is a form of collapse therapy that was used in the treatment of cavitary pulmonary tuberculosis before the availability of antimycobacterial chemotherapy. We report a series of cases of far-advanced pulmonary disease due to multiple-drug-resistant Mycobacterium tuberculosis, wherein artificial pneumoperitoneum with or without subsequent surgical extirpation was used as an adjunct to chemotherapy. Overall, among these desperate cases, therapeutic pneumoperitoneum provided no clear benefit.

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We treated five patients with a past history of tuberculous pleural infection that led to chronic, quiescent, loculated empyema. Reactivation of TB was associated with formation of BPF and recovery of drug-susceptible Mycobacterium tuberculosis from sputum. All patients had recurrence of positive sputum cultures that yielded tubercle bacilli resistant to drugs they were receiving. The lungs demonstrated gross thickening with calcification of both visceral and parietal pleura. Two patients underwent retreatment chemotherapy followed by decortication-empyemectomy and lung resection surgery; both are now culture-negative for TB. One patient received retreatment chemotherapy but refused surgery; he remains clinically stable with negative sputum cultures. Two other patients' organisms became drug-resistant and they remain sputum-culture positive. We believe that thick, calcified pleural walls limit penetration of drugs into the infected empyema space, resulting in suboptimal drug concentrations and drug resistance. Intensified chemotherapy and surgical intervention should be considered in these cases.

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Multiply resistant tuberculosis is on the rise throughout the world. It poses the risk that an increasing percentage of patients will have disease that cannot be cured in economically limited nations and, thus, resistant tubercle bacilli will be spread in an exponential manner. For such patients in the United States, aggressive chemotherapy, coupled with surgery in cases of localized disease, is the best hope for cure.

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