From geotechnical maps to three-dimensional models

It is generally preferable to store geotechnical and geological investigation material for possible future use. Old material may be even more valuable than new results in some cases. If the location data for site investigations cannot be identified reliably, it is usually advisable to refrain from using the data at all. Quaternary maps compiled by the Geological Survey of Finland are available for the entire country. Some municipalities in areas where foundation conditions play a prominent part in the safety and economy of building have worked up their own foundation survey materials into regional geotechnical maps. The use of geotechnical data for planning has always required a three-dimensional viewpoint. 3D analysis requires a joint GIS-type database. These still generally consist of binary files, although a relational database solution is recommended for the management of large bodies of data in particular. The general principle as regards old investigations is that their costs have already been covered, whereas overwise separate search and maintenance costs will be involved. Data users are themselves responsible for the results of older site investigations. One important feature is that geotechnical data can be combined with information obtained from other systems.     

Ultrathin Dual‐Scale Nano‐ and Microporous Membranes for Vascular Transmigration Models

Selective cellular transmigration across the microvascular endothelium regulates innate and adaptive immune responses, stem cell localization, and cancer cell metastasis. Integration of traditional microporous membranes into microfluidic vascular models permits the rapid assay of transmigration events but suffers from poor reproduction of the cell permeable basement membrane. Current microporous membranes in these systems have large nonporous regions between micropores that inhibit cell communication and nutrient exchange on the basolateral surface reducing their physiological relevance. Here, the use of 100 nm thick continuously nanoporous silicon nitride membranes as a base substrate for lithographic fabrication of 3 µm pores is presented, resulting in a highly porous (≈30%), dual‐scale nano‐ and microporous membrane for use in an improved vascular transmigration model. Ultrathin membranes are patterned using a precision laser writer for cost‐effective, rapid micropore design iterations. The optically transparent dual‐scale membranes enable complete observation of leukocyte egress across a variety of pore densities. A maximal density of ≈14 micropores per cell is discovered beyond which cell–substrate interactions are compromised giving rise to endothelial cell losses under flow. Addition of a subluminal extracellular matrix rescues cell adhesion, allowing for the creation of shear‐primed endothelial barrier models on nearly 30% continuously porous substrates.     

Fluorescence quenching-based assays for hydrolyzing enzymes. Application of time-resolved fluorometry in assays for caspase, helicase, and phosphatase

We have developed assay technologies to measure hydrolyzing enzymes based on homogeneous time-resolved fluorescence quenching (TruPoint). High sensitivity was obtained using fluorescent europium chelates as labels, internally quenched by suitable quenchers and released upon enzymatic reaction. This approach allows robust and sensitive monitoring of low enzyme activities. The assay technology and the choice of donor-acceptor pairs were evaluated in three different enzymatic assays, a protease related to apoptosis, helicase involved in DNA unwinding, and phosphatase having an important role in cellular signaling cascades. All the assays produced an increasing signal, were sensitive, and had a good dynamic range. There were significant differences in optimized quenchers for each of the assays depending on the size, flexibility, and rigidity of the substrates. Also, clear differences in the energy-transfer reactions, their requirements for spectral overlapping, ionic interactions, and energy-transfer distances were found. Each of the enzymatic assays was briefly tested in a high-throughput screening environment by analyzing signal dynamics and statistical relevance as Z' factors.     

Dichromated Gelatin Reflection Gratings

Abstract

Reflection gratings were recorded in dichromated gelatin by using a non-symmetrical recording geometry. In addition to the primary grating, secondary gratings were also formed, as is generally known. It is found that the secondary gratings assist the structure stability during development in the exposure energy range (50–100) mJ cm^?2. The structure containing these secondary gratings is more rigid than those without and the reflection grating period is more stable during the development process in this exposure energy range, which is most suitable for the transmission grating formation. Secondary gratings also cause unwanted noise, but the noise level is low and the improved stability outweighs the extra noise.     

Toxicological screening with formula-based metabolite identification by liquid chromatography/time-of-flight mass spectrometry

An analytical procedure was evaluated for the comprehensive toxicological screening of drugs, metabolites, and pesticides in 1-mL urine samples by TurboIon spray liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) in the positive ionization mode and continuous mass measurement. The substance database consisted of exact monoisotopic masses for 637 compounds, of which an LC retention time was available for 392. A macroprogram was refined for extracting the data into a legible report, utilizing metabolic patterns and preset identification criteria. These criteria included +/-30 ppm mass tolerance, a +/-0.2-min window for absolute retention time, if available, and a minimum area count of 500. The limit of detection, determined for 90 compounds, was <0.1 mg/L for 73% of the compounds studied and >1.0 mg/L for 6% of the compounds. For method comparisons, 50 successive autopsy urine samples were analyzed by this method, and the results confirmed by gas chromatography/mass spectrometry (GC/MS). Findings for parent drugs were consistent with both methods; in addition, LC/TOFMS regularly revealed apparently correct findings for metabolites not shown by GC/MS. Mean and median mass accuracy by LC/TOFMS was 7.6 and 5.4 ppm, respectively. The procedure proved well-suited for tentative identification without reference substances. The few false positives emphasized the fact that all three parameters, exact mass, retention time, and metabolite pattern, are required for unequivocal identification.     

Demonstration of safety of probiotics -- a review

Probiotics are commonly defined as viable microorganisms (bacteria or yeasts) that exhibit a beneficial effect on the health of the host when they are ingested. They are used in foods, especially in fermented dairy products, but also in pharmaceutical preparations. The development of new probiotic strains aims at more active beneficial organisms. In the case of novel microorganisms and modified organisms the question of their safety and the risk to benefit ratio have to be assessed. Lactic acid bacteria (LAB) in foods have a long history of safe use. Members of the genera Lactococcus and Lactobacillus are most commonly given generally-recognised-as-safe (GRAS) status whilst members of the genera Streptococcus and Enterococcus and some other genera of LAB contain some opportunistic pathogens. Lactic acid bacteria are intrinsically resistant to many antibiotics. In many cases resistances are not, however, transmissible, and the species are also sensitive to many clinically used antibiotics even in the case of a lactic acid bacteria- associated opportunistic infection. Therefore no particular safety concern is associated with intrinsic type of resistance. Plasmid-associated antibiotic resistance, which occasionally occurs, is another matter because of the possibility of the resistance spreading to other, more harmful species and genera. The transmissible enterococcal resistance against glycopeptide antibiotics (vancomycin and teicoplanin) is particularly noteworthy, as vancomycin is one of the last effective antibiotics left in the treatment of certain multidrug-resistant pathogens. New species and more specific strains of probiotic bacteria are constantly identified. Prior to incorporating new strains into products their efficacy should be carefully assessed, and a case by case evaluation as to whether they share the safety status of traditional food-grade organisms should be made. The current documentation of adverse effects in the literature is reviewed. Future recommendations for the safety of already existing and new probiotics will be given.     

HIV-1 genetic subtype A/B recombinant strain causing an explosive epidemic in injecting drug users in Kaliningrad

OBJECTIVES: To investigate the molecular epidemiology and genetic structure of the virus strain(s) causing an outbreak of HIV-1 infection in the Kaliningrad province of the Russian Federation and to investigate the relationship of this outbreak to some other emerging HIV-1 epidemics in the countries of the former Soviet Union. DESIGN: A molecular epidemiological investigation was conducted in the city of Kaliningrad amongst individuals recently diagnosed as HIV-1-positive. Samples were also collected from neighbouring Lithuania and from the Ukraine. METHODS: Incident and population data was collected from official health statistics in Kaliningrad. A standardized questionnaire was administered to newly diagnosed individuals to assess risk factors for HIV-1 infection. For genotyping, two regions of the virus (env C2-V3 and gag NCp7) were directly sequenced. RESULTS: The number of newly diagnosed individuals testing seropositive for HIV-1 infection in Kaliningrad rose from less than one per month to more than 100 per month during the period of July-October 1996. A total of 1335 new infections were identified between 1 July 1996 and 30 June 1997. The main reported risk factor for HIV-1 infection (80%) was injecting drug use, in particular with a locally produced opiate. Sequence analysis of patient viruses in Kaliningrad (n = 50) showed that the epidemic was caused by a highly homogenous HIV-1 strain, recombinant between the genetic subtypes A and B. Comparison with subtype A strains prevalent amongst injecting drug users (IDU) in the Ukraine showed that one of these strains was the direct subtype A parent of the epidemic A/B recombinant strain in Kaliningrad. CONCLUSIONS: The HIV-1 epidemic in Kaliningrad probably started from a single source, with rapid spread of the virus through the IDU population. The origin of the epidemic strain is a recombination event occurring between the subtype A strain virus prevalent among IDU in some southern CIS countries, and a subtype B strain of unknown origin.     

Improving the Accuracy of Structural Hot‐spot Stress Approach

A method for extending the applicability of the structural hot‐spot stress method for fatigue assessment of welded structures is discussed. The structural hot‐spot stress method for plate structures, as currently presented in commonly used design guidance documents, cannot account for the effect of weld size, and load carrying fillet welds are assessed using a different S‐N curve as compared to non‐load carrying fillet welds. This paper presents a proposal to linearize the local stress distribution through the plate thickness in the plane of the weld toe. This proposal considers the forces transmitted by the weld itself. A bilinear stress distribution, which partially captures the local effect of the weld, is derived from the non‐linear stress distribution. The non‐linear distribution is based on equilibrium and the stress in the fillet weld. A simple procedure is presented to determine the bilinear curve from the nominal weld stress. This is a great advantage in finite element analysis when only nominal base plate stress and nominal weld stresses need to be determined. When compared to the more conventional structural stress approach, the new method also has the advantage that extrapolation is not required. The same weld stresses can also be used in the analysis of the root cracks. The proposed method was scaled to correspond to the traditional structural hot‐spot stress method using detailed linear elastic fracture mechanics simulations. The method is only applied to fully load‐carrying welds here but can also be used for partial load‐carrying welds. A symmetric splice plate having a fully loaded fillet weld is presented as an example case. The influence of base plate thickness is studied as well.     

Age-dependent correlation of low-back pain and lumbar disc regeneration

The prevalence of lumbar disc degeneration in subjects suffering from low-back pain (n = 207; age range 10-49 years) and in age-matched asymptomatic controls (n = 216) was investigated by magnetic resonance imaging. The percentage of subjects with degenerated discs increased with age; starting from the age of 15 years, this increase was more rapid in subjects with low-back pain. Concurrently, the number of degenerated discs was higher in the pain group than in controls. Lumbar disc degeneration manifests earlier and in a greater percentage of subjects with low-back pain than in asymptomatic controls.