Updating of a DRASTIC-based Method for Specific Vulnerability Assessment in Carbonate Aquifers

Abstract

Some methodological modifications are suggested to improve a DRASTIC-based method as a reliable predictor of microbial contamination in extensively fractured and subordinately karstified carbonate aquifers. These modifications will allow a better assessment of vulnerability induced by the concentrated infiltration of surface runoff in two different scenarios: (a) when the karst system is entirely located within an unsaturated aquifer and (b) when the karst system is partially located within a saturated medium. The effectiveness of the updated method has been experimentally verified by comparing the vulnerability values with the results of a hydrogeological and microbiological study at a test site.     

Thinking about Antarctic Heritage: Kaleidoscopes and filters

The preliminary results of a project that is currently investigating the nature and range of meanings of Antarctic heritage are explored. The project involves two visits to Scott Base, and the subjects of the qualitative research are the members of the New Zealand Antarctic community. Work so far suggests that different meanings do exist, and a four-fold typology of meanings is suggested which needs to be considered in decisions affecting the future of Antarctica.     

Development and application of a new time–temperature integrator for the measurement of P-values in mild pasteurisation processes

A new time–temperature integrator (TTI) for the measurement of mild pasteurisation treatments is described. The objective was to measure thermal processes of the order of a few minutes at 70 °C. Food products that receive these treatments are intended for sale either under refrigerated conditions with <10 days storage, or are naturally high in acid that allows ambient storage for many months. The new TTI, referred to as BAA70, consisted of 0.5 mg/mL α-amylase from Bacillus amyloliquefaciens in 10 mM acetate buffer. Decimal reduction time (D₇₀-value) of 8.4 min and z-value of 8.9 C° were calculated for BAA70 in a water bath. Maximum P-values measured with BAA70 were up to 25.2 min at 70 °C. Industrial evaluation for surface pasteurisation in hot-filled mini jam jars and for continuous oven cooking of quiches demonstrated the applicability of the BAA70 TTI. P-Values in both these operations could not be measured using conventional temperature sensors and so the TTIs provided invaluable data on pasteurisation achieved.     

Innovation or Notoriety?

The purpose of this column is to give some perspective and words of advice to new inventors. When you choose to be an innovator, you will have lots of fun intellectually, but the road can be pretty bumpy when it comes to the politics of receiving proper credit for your ideas, and when it comes to "selling" your ideas and seeing them through to implementation. This column documents some of the possible bumps in the road, including the three stages toward acceptance of a new idea: ridicule, opposition, and obviousness.     

Automated strategies to identify compounds on the basis of GC/EI-MS and calculated properties

The identification of unknown compounds based on GC/EI-MS spectrum and structure generation techniques has been improved by combining a number of strategies into a programmed sequence. The program MOLGEN-MS is used to determine the molecular formula and incorporate substructural information to generate all structures matching the mass spectral information. Mass spectral fragments are then predicted for each structure and compared with the experimental spectrum using a match value. Additional data are then calculated automatically for each candidate to allow exclusion of candidates that did not match other analytical information. The effectiveness of these "exclusion criteria", as well as the programming sequence, was tested using a case study of 29 isomers of formula C(12)H(10)O(2). The default classifier precision resulted in the generation of too many structures in some cases, which was improved by up to several orders of magnitude by including additional classifiers or restrictions. Combining this with the exclusion of candidates based on a Lee retention index/boiling point correlation, octanol-water partitioning coefficients, steric energies, and finally spectral match values limited the number of candidate structures further from over 1 billion without any restrictions down to less than 6 structures in 10 cases and below 35 in all but 3 cases. This method can be used in the absence of matching database spectra and brings unknown identification based on MS interpretation and structure generation techniques a step closer to practical reality.     

Stray light correction for diode-array-based spectrometers using a monochromator

Photodiode-array-based spectrometers are increasingly being used in a wide variety of applications. However, the signal measured by this type of instrument often is not what is anticipated by the user and is often subject to contamination from stray light. This paper describes an efficient and low-cost stray light correction approach based on a relatively simple system using a monochromator-based source. The paper further discusses the limitations of using a monochromator instead of a laser, as used by previous researchers, and its impact on the quality of the stray light correction. The reliability and robustness of the stray light correction matrix generated have been studied and are also reported.     

Comparative analysis of breast cancer contamination in mobilized and nonmobilized hematopoietic grafts

We report a case of an 18-month-old female who presented with three supernumerary upper limbs of varying lengths on the right side. Each limb had a proximal, middle, and distal segment, and an intercalated elbow and wrist joint. A single digit was present in the superior limb, three digits in the middle limb, and two digits in the caudal-most limb. Right plagiocephaly, congenital torticollis, scoliosis involving the upper and mid thoracic region, and a hypoplastic right pectoralis major were the other abnormal features noted. Radiography showed two scapulae, humerus, a single forearm bone in each limb, and rudimentary metacarpals and phalanges. Limb duplication may rarely be encountered in parasitic conjoined twins. The role of mutagens, drugs, cellular contributions, and morphogens in the growth and differentiation of limbs has been studied in animals. It is rather difficult to deduce the time of action of the factors responsible for such a malformation.     

Determination of heavy metals in milk by potentiometric stripping analysis using a home-made flow cell

A method is described for sensitive and reliable determination of trace concentrations of cadmium, lead and copper in real samples by stripping potentiometry with a home-made flow cell. The selection of the experimental conditions was made using experimental design methodology. The optimum conditions for the method include an acetic acid–acetate buffer mixture (pH 3.4) as supporting electrolyte, an electrolysis potential of −1.1 V and a flow rate of 3 ml min⁻¹. The detection limits were 6.51 × 10⁻¹⁰ mol l⁻¹ for cadmium, 4.60 × 10⁻¹⁰ mol l⁻¹ for lead and 8.59 × 10⁻¹⁰ mol l⁻¹ for copper, with an electrolysis time of 900 s. The relative standard deviations at this concentration level were 0.038, 0.086 and 0.095, respectively. In order to check the analytical accuracy, standard solutions have been used and recoveries close to 100% were obtained. The method was successfully applied to the determination of cadmium, lead and copper in powdered milk, using the method of standard additions.