Kinetics of 1,1,1-trichloroethane transformation by iron sulfide and a methanogenic consortium

To evaluate the effect of potential interactions between methanogenic bacteria and iron sulfide minerals during transformation of 1,1,1-trichloroethane (1,1,1-TCA), we measured the kinetics of 1,1,1-TCA transformation by mackinawite (FeS(1 - x), but abbreviated as FeS) and a methanogenic consortium enriched on lactate (termed LEC). Results from batch kinetic experiments show that 1,1,1-TCA transformation by FeS and resting LEC can be described by second-order rate expressions, with rates depending on 1,1,1-TCA concentration (M), FeS surface area concentration (m2 L(-1)), and LEC concentration (as measured by mg L(-1) volatile suspended solids (VSS)). In reactors containing FeS alone, 1,1-dichloroethane (1,1-DCA) and 2-butyne were identified as products, but only accounted for 6% of the 1,1,1-TCA transformed. In reactors containing LEC alone, the only identified product was 1,1-DCA, which accounted for 46 +/- 8% of the 1,1,1-TCA transformed. Supernatant from LEC-alone reactors also transformed 1,1,1-TCA, suggesting that 1,1,1-TCA may be transformed by some non-cell component (such as a extracellular compound excreted by the organisms) that either reacts directly with 1,1,1-TCA or with the abiotic media to form a reactive species. Comparison of 1,1,1-TCA transformation rates from experiments with combinations of FeS (varying surface area concentrations) and LEC (varying VSS concentrations) to those with just FeS alone or LEC alone suggests some synergism occurs between the two reactive species. Observed enhancements took the form of faster 1,1,1-TCA transformation and faster 1,1-DCA appearance but less production of 1,1-DCA per unit of 1,1,1-TCA transformed. These observations suggest that the faster 1,1,1-TCA transformation in the combined systems (compared to the FeS-alone and LEC-alone experiments) is due to increased reactivity of both FeS and LEC, possibly due to production of soluble microbial products that make the FeS more reactive or less inhibition of LEC by 1,1,1-TCA due to FeS transformation of 1,1,1-TCA.     

Inhibitory effect of 0 degree C storage on the proliferation of Yersinia enterocolitica in donated blood

BACKGROUND: Yersinia enterocolitica is frequently identified in cases of bacterial sepsis due to red cell transfusion. One of the features that makes Y. enterocolitica particularly dangerous is that, unlike most other bacterial contaminants of blood components, this organism can actively multiply in currently recommended refrigerator temperatures (1-6 degrees C). The effect of a colder than normal storage temperature on Y. enterocolitica growth was investigated to determine whether bacteria growth could be reduced or inhibited at 0 degree C. STUDY DESIGN AND METHODS: Twenty-four units of freshly collected donated blood were obtained. Three sets of 7 units each were inoculated with Y. enterocolitica O:3, Y. enterocolitica O:20, and Y. enterocolitica O:5, 27, respectively. The remaining 3 units served as uninoculated controls. Each of the 24 bags was split into two equal aliquots, with one aliquot stored at 4 degrees C and the other at 0 degree C. Bacteria growth was measured twice weekly for 6 weeks. Endotoxin and hemoglobin levels were also measured at selected intervals. RESULTS: Bacteria growth was detected earlier and in higher concentrations in the aliquots stored at 4 degrees C. Twenty-two of the 42 inoculated aliquots had measureable bacteria growth. Thirteen aliquots had been maintained at 4 degrees C, and nine had been stored at 0 degree C. Sixteen of these 22 aliquots were matched pairs. Exponential growth was detected after 14 to 32 days in the 4 degrees C aliquots and after 28 to 39 days in the 0 degree C aliquots. Final bacteria counts were much higher in the 4 degrees C aliquots (10(5)-10(14) colony-forming units/mL) than in the 0 degree C aliquots (10(1)-10(4) colony-forming units/mL) on Day 42. Endotoxin was present in all 13 of the 4 degrees C aliquots with actively growing Y. enterocolitica. CONCLUSION: Storage of red cells at 0 degree C markedly prolongs the time required for Y. enterocolitica to achieve exponential grwoth and results in lower concentrations of bacteria.     

Optimized waveform relaxation methods for RC type circuits

Waveform relaxation (WR) has been widely used in circuit theory for the solution of large systems of ordinary differential equations, and the solution of partial differential equations. In the past, clever partitioning schemes have been used for circuit applications to enhance convergence. However, a drawback of the classical WR algorithm is the nonuniform convergence over the window in time for which the equations are integrated. We propose a new optimized WR algorithm which greatly accelerates the convergence by introducing new transmission conditions. These conditions are responsible for the exchange of information between the subcircuits. We use two RC circuit examples to illustrate the theory, as well as the improved convergence behavior.     

The future of pathology: a Delphi study by pathology department chairmen

This paper reports the results of a study by and of chairmen of pathology departments in American and Canadian medical schools directed toward discovering chairmen's perceptions and attitudes about the future of pathology. Over 100 of a total of 143 chairmen participated in some or all phases of this study in which the Delphi approach was used. Sixty-five chairmen completed all four rounds of questionnaires. Most chairmen are deeply concerned about increasing federal regulation of medicine. They expect to play a greater role in all phases of medical education with more emphasis on the basic science aspects of pathology. They also foresee a desirable shifting of residency training programs away from small hospitals to the larger medical centers. This shift will result in fewer but longer training programs.     

Real-time digital median frequency estimator for surfacemyoelectric signals

A prototype instrument is described that uses a digital signal processor to estimate the median frequency of the myoelectric signal in real time. A set of tenth-order digital low-pass filters is used to track the median frequency. An estimate of frequency is obtained once every 256 ms with a resolution of 1 Hz.     

A high performance amplitude/phase modulated digital-to-synchro switching power converters

In this paper, a high performance three-phase switching digital-to-synchro (D/S) power converter is proposed for driving high power synchro motors. An amplitude/phase modulation algorithm is implemented with digitally controlled sinusoidal pulse-width-modulation. Design methodology and synchronization improvement are also presented. The generated synchro format output is first verified by simulation and then by a digital signal processor controlled hardware prototype testing. Experimental results indicate that the switching amplifier based D/S converter not only shrinks the size over the conventional linear amplifier based unit, but also demonstrates superior performance to the commercially available unit.     

Role of Milling Parameters and Particle Stabilization on Nanogrinding of Drug Substances of Similar Mechanical Properties

The feasibility and efficiency of wet‐nanogrinding of three drug substances (miconazole, itraconazole, etravirine) with similar elastic and plastic properties proved to depend primarily on the adequate electrostatic and steric stabilization of the nanoparticles and the specific energy input. Particle stabilization was provided by sodium dodecyl sulfate (SDS) and hydroxypropylcellulose. The specific energy input was defined by the grinding time, grinding bead size, and stirrer tip speed. Miconazole and itraconazole exhibited similar milling behavior, whereas etravirine nanosuspensions revealed agglomerates and increasing viscosity with increasing specific energy input. Agglomeration and viscosity increase were successfully counteracted by increasing the SDS concentration in the nanosuspension from 0 to 0.125 %. Under the provision of proper particle stabilization, the three drug substances could be nanosized to a mean size of ～ 130 nm, with 90 % of all particles being smaller than ～ 250 nm.     

Inter–organisational Relationships in the Worldwide Popular Recorded Music Industry

This paper analyses the worldwide popular recorded music industry and examines how product, firm and industry features result in key resources coagulating around the two firm types; the major and independent. We argue that these firm specific resources are complementary and participating firms would benefit from their union. However though complementary, they are inimical and close association risks damaging their value. Collaboration between the two firm types that hold these resources therefore needs to be designed not along traditional concerns of protection from opportunism, or the requirement to control key resources. Instead competitive advantage may be gained by designing and managing structural relationships that protect each partner’s resource set from the hostile elements of the others; a contamination rather than an appropriation focus.