Microbial transformations of arsenic: mobilization from glauconitic sediments to water

In the Inner Coastal Plain of New Jersey, arsenic (As) is released from glauconitic sediment to carbon- and nutrient-rich shallow groundwater. This As-rich groundwater discharges to a major area stream. We hypothesize that microbes play an active role in the mobilization of As from glauconitic subsurface sediments into groundwater in the Inner Coastal Plain of New Jersey. We have examined the potential impact of microbial activity on the mobilization of arsenic from subsurface sediments into the groundwater at a site on Crosswicks Creek in southern New Jersey. The As contents of sediments 33-90 cm below the streambed were found to range from 15 to 26.4 mg/kg, with siderite forming at depth. Groundwater beneath the streambed contains As at concentrations up to 89 μg/L. Microcosms developed from site sediments released 23 μg/L of As, and active microbial reduction of As(V) was observed in microcosms developed from site groundwater. DNA extracted from site sediments was amplified with primers for the 16S rRNA gene and the arsenate respiratory reductase gene, arrA, and indicated the presence of a diverse anaerobic microbial community, as well as the presence of potential arsenic-reducing bacteria. In addition, high iron (Fe) concentrations in groundwater and the presence of iron-reducing microbial genera suggests that Fe reduction in minerals may provide an additional mechanism for release of associated As, while arsenic-reducing microorganisms may serve to enhance the mobility of As in groundwater at this site.     

Mechanisms of Drying of Skin-Forming Materials. II.Droplets of Heat Sensitive Materials

ABSTRACT

Drying studies were carried out on single droplets of gelatin solution, typifying a skin forming, heat-sensitive material. Each droplet was suspended from a novel rotating glass nozzle which enabled direct measurement of its weight and temperature during drying. Observations using this appartatus successfully detected the decrease in core temperature and increase in drying rate resulting from granule dissolution at 30 °C.

The study covered air temperatures in the range 19 °C–175 °C. Scanning Electron Microscopy was used to examine the dried crusts. The resistance of the skin to vapour diffusion was significantly increased with an increase in the air temperature. At air temperature > 60 °C the dried particle lost the structure and properties of the original powder. The optimum drying conditions to avoid this were predicted for this type of skin forming-material.     

Hyperferritinaemia in the absence of iron overload

We present a case of a 3-month-old boy presenting with fulminating meningococcal septicaemia associated with extensive peripheral gangrene requiring amputation of three limbs. The surgical management options and the role of early fasciotomy are discussed.     

Volatiles Retention in the Drying of Skin Forming Materials PART 3: Heat-Sensitive Materials

Ethanol retention in solutions was determined by drying single droplets in a horizontal wind tunnel, with gelatine (Bloom numbers 60 and 150) and gum arabic as encapaulants. The variation in ethanol content, droplet temperature history and crust structure were evaluated in each case. General conclusions are provided for parameters determining volatile- retention in convective drying.     

Public veterinary medicine: public health. Serologic evaluation of vesicular stomatitis virus exposure in horses and cattle in 1996

OBJECTIVE: To determine potential risk factors for vesicular stomatitis (VS) in Colorado livestock in 1995 and evaluate VS virus (VSV) exposure of Colorado livestock in 1996. DESIGN: Retrospective case-control study of VS risk factors and seroprevalence evaluation. SAMPLE POPULATION: Premises included 52 that had VS-positive animals and 33 that did not have VS-positive animals during the 1995 epidemic, and 8 in the vicinity of premises that had VS-positive animals during the 1995 epidemic. PROCEDURE: Layout and management data for premises were collected during site visits in 1996. Signalment and management data were collected for animals from which samples were obtained, and samples were tested by serologic examination and virus isolation. The VSV seroprevalence rate was estimated for Colorado, using serum obtained for equine infectious anemia testing and from the Market Cattle Identification program in Colorado. RESULTS: At least 1 animal was seropositive for VSV on 35 of 52 (67%) premises, and 71 of 228 (31%) animals tested were seropositive for VSV. Seroprevalence was 63 of 170 (37%) for horses and 8 of 54 (15%) for cattle. Seroprevalence of VSV in animals from non-study premises in Colorado in 1996 was estimated to be 1.1% in cattle and 0.8% in horses. CLINICAL IMPLICATIONS: Overall VSV seroprevalence in Colorado livestock was less than seroprevalence in epidemic areas, and seroprevalence rates in epidemic areas were greater for horses than cattle. Results may indicate that some animals had subclinical VSV infection during epidemics and that animals may be exposed to VSV between epidemics.     

Time Synchronization Error and Calibration in Integrated GPS/INS Systems

The necessity for the precise time synchronization of measurement data from multiple sensors is widely recognized in the field of global positioning system/inertial navigation system (GPS/INS) integration. Having precise time synchronization is critical for achieving high data fusion performance. The limitations and advantages of various time synchronization scenarios and existing solutions are investigated in this paper. A criterion for evaluating synchronization accuracy requirements is derived on the basis of a comparison of the Kalman filter innovation series and the platform dynamics. An innovative time synchronization solution using a counter and two latching registers is proposed. The proposed solution has been implemented with off‐the‐shelf components and tested. The resolution and accuracy analysis shows that the proposed solution can achieve a time synchronization accuracy of 0.1 ms if INS can provide a hard‐wired timing signal. A synchronization accuracy of 2 ms was achieved when the test system was used to synchronize a low‐grade micro‐electromechanical inertial measurement unit (IMU), which has only an RS‐232 data output interface.     

Optimisation of a liquid extraction process

A mathematical model of a solvent extraction process has been developed which has been arranged into a form suitable for optimising the process by the indirect optimisation procedure and by the direct method developed by Hooke and Jeeves. These optimisation procedures have been compared by analysing an extraction process in which solvent recovery is by distillation.     

Mechanisms of Drylng of Skin-Forming Materials; the Significance of Skin Formation and a Comparison Between Three Types of Material

Comparisons are drawn between the drying characteristics, and the mechanisms of skin formation on, three characteristic types of material. The significance of skin formation, which may be a major factor in valatiles retention in the drying of spray dried products, is discussed. The optimum drying conditions to achieve the highest volatiles retention for each type of skin-forming material are predicted. General comparisons are also drawn between the drvine of skin-formine i.e., materials which form a smooth flexible low- parosity skin at same slage, and normal crust-forming materials. The latter form only a rigid crust with a porosity which is system and drying-condition dependent.