Effects of some calcium-related agents on the protoplast transfection of Lactobacillus casei with phage PL-1 DNA

An audit of the treatment procedures routinely adopted by maxillofacial and oral surgeons for the removal of impacted third molars under general anaesthesia was undertaken in South Africa. Most maxillofacial and oral surgeons agree on the method of bone removal, the prescribing of antibiotics, analgesic agents and mouthwashes, the suturing of the incision wound and the post-operative review of patients. The results were compared to a similar study undertaken by Falcon and Roberts (1992) in the UK. With the exception of the method of bone removal, maxillofacial and oral surgeons in both groups share a similar approach to the treatment procedures adopted in the removal of impacted third molars. Some variability, however, existed in both studies with regard to the use of intra-operative local anaesthetic agents, the administration of peri-operative steroids and the use of non-steroidal anti-inflammatory agents.     

The effect of a split in WAIS-R VIQ and PIQ scores on patients with cognitive impairment and psychiatric illness

To determine the most effective treatment for acrodermatitis chronica atrophicans, several clinical trials were undertaken in recent years to evaluate whether a 2-week course of ceftriaxone would be superior to oral antibiotics. Of the 46 patients suffering from acrodermatitis chronica atrophicans, 14 were treated with ceftriaxone 2g for 15 days. The remaining patients received either oral penicillin V 1.5 million IU t.i.d. or doxycycline 100 mg b.i.d. for 20 to 30 days. Patients were followed up for at least 1 year. Of the 14 ceftriaxone-treated patients four showed incomplete regression of the inflammatory skin changes after 6 to 12 months. Two out of five patients who were monitored for Borrelia burgdorferi DNA excretion were still positive after 12 months as compared to none of six patients who were treated orally for 20-30 days. Six out of 11 patients treated orally for only 20 days needed retreatment after 6 months because of continuing skin manifestations, neuropathy or arthralgia. A 30-day duration of treatment with oral antibiotics and not the chosen antibiotic is crucial for curing acrodermatitis chronica atrophicans. The duration of treatment with ceftriaxone needed for eradication of Borrelia in acrodermatitis chronica atrophicans has yet to be determined in future studies.     

Smart computational fracture of materials and structures

The use of the finite element method for complex engineering problems is now common. To ease the burden on the engineer the development of smart or adaptive computational methods is now required to model complex problems. In this paper we investigate the development of an adaptive finite element method for fracture-related problems. The adaptive method involves various stages which include the finite element analysis, error estimation/indication, mesh refinement and fracture/failure analysis in a loop. Some simple error estimators, based on stress projection, are used to investigate the adaptive finite element process. Element refinement is based on three schemes; the first and second are a simple and hierarchical refinement scheme with transitioning which avoids the need for constraint equations between element boundaries. Another scheme based on constraint equations between elements is also examined. The energy norm is used to estimate the element error. The software has the ability to introduce a discrete fracture in the structure according to standard fracture analysis practice. Crack tip parameters are calculated using a least-squares fit of the displacements into the asymptotic crack tip displacement field. Some simple examples are used to investigate the adaptive process, its behavior and some of the practical problems encountered. The convergence and equilibrium of the adaptive process, in terms of global error in the energy norm, are investigated. In the example the same problem is analyzed using both a fine computational grid and a coarse one. The coarse mesh is then adapted using the three different procedures available. The estimated error in the solution and the stress intensity are shown against the number of elements and number of iterations. Some further areas of research in adaptive finite element analysis are discussed.     

Influence of series resistance in oxide parameter extraction data from accelerated tests

Accelerated reliability tests on thin oxide capacitors can be affected by series resistance effects at high stress conditions. The purpose of this work is to point out such problems both with measurements and simulations. It is shown that breakdown electric field is overestimated. Due to the resulting nonuniform stress, charge to breakdown density is underestimated if the test structure layout is not accurately designed. In any case the series resistance effects can have an undesirable impact on the reliability evaluation of thin dielectrics.     

Gene amplification in Chinese hamster DNA repair deficient mutants

In order to study the possible relationship between gene amplification and DNA repair we analyzed the amplification of the CAD gene in four mutants hypersensitive to UV light (CHO43RO, CHO7PV, UV5 and UV61) isolated in vitro from Chinese hamster cell lines (CHO-K1 and AA8). These mutants are characterized by different defects in the nucleotide excision repair mechanism and represent complementation groups 1, 9, 2, and 6 respectively. To evaluate the amplification ability of each cell line we measured the rate of appearance of PALA resistant clones with the Luria and Delbrück fluctuation test. Resistance to PALA is mainly due to amplification of the CAD gene. In the mutants CHO43RO, UV5 and CHO7PV we reproducibly found an amplification rate lower than in the parental cell lines (2-5 times), while in UV61 the amplification rate was about 4 times higher. This result indicates that each mutant is characterized by a specific amplification ability and that the unefficient removal of UV induced DNA damage can be associated with either a higher or a lower amplification rate. However, the analysis of randomly isolated CHO-K1 clones with normal UV sensitivity has shown variability in their amplification ability, making it difficult to relate the specific amplification ability of the mutants to the DNA repair defect and suggesting clonal heterogeneity of the parental population.     

Gain equalization by mitigating self-filtering effect in a chain ofcascaded EDFA's for WDM transmissions

A simple method of alternatively using high-inversion and moderate-inversion erbium-doped fiber amplifiers (EDFA's) in an optical amplifier chain is presented to mitigate the self-filtering effect and equalize both signal power and signal-to-noise ratio (SNR) of multiple wavelength channels in wavelength-division multiplexing (WDM) transmission systems. The performance of the compensated system with alternatively used high- and moderate-inversion amplifiers is compared with the uncompensated ones where only moderate- or high-inversion amplifiers are employed. The result shows that the compensated system has a flatter gain profile, a lesser signal power spread, and SNR degradation     

Heterotopic replantation

In multidigital amputations, it is sometimes better to replant an amputated finger to a different proximal part if a better function can be expected in this position. In our clinical material between October 1991 and March 1994, heterotopic replantation was performed in twelve digits in eleven patients. Three fingers were replanted to the thumb, three to the index, four to the middle, and two to the ring fingers. The functional results were satisfying. The total active range of motion was on an average 24% of a normal finger. Static two-point discrimination was 8.5 mm on an average, and the values for the Semmes-Weinstein test ranged between 3.61 and 6.5. A heterotopic replantation is of special value for primary thumb reconstruction.     

Full scale thermal testing of latent heat storage in wallboard

Full scale thermal storage tests were conducted in a room lined with PCM wallboard having latent heat storage capacity. The results were compared with those obtained from tests conducted in a similar room lined with ordinary wallboard. The research showed that PCM wallboard can function efficiently as a thermal storage medium which can be applied to peak load shifting, improved use of waste and solar heat as well as more efficient operation of heating and cooling equipment.     

Encapsulation of PV modules using ethylene vinyl acetate copolymer as a pottant: A critical review

The primary purpose of this work is to review the literature about what is and is not known about using ethylene vinyl acetate (EVA0 copolymer as the encapsulant (or pottant) material in photovoltaic (PV) modules. Secondary purposes include elucidating the complexity of the encapsulation problem, providing an overview about encapsulation of PV cells and modules, providing a historical overview of the relevant research and development on EVA, summarizing performance losses reported for PV systems deployed since ca. 1981, and summarizing the general problems of polymer stability in a solar environment. We also provide a critical review of aspects of reported work for cases that we believe are important.Failure modes resolved in the early work to establish reliability of deployed modules and the purposes and properties of pottants, are summarized. Typical performance losses in large field-deployed, large-scale systems ranging from 1% to 10% per year are given quantitatively, and qualitative reports of EVA discoloration are summarized with respect to ultraviolet (UV), world-wide location and site dependence.The general stability of polymers and their desirable bulk properties for solar utilization are given. The stabilization formulation for EVA, its effectiveness, and changes in it during degradation are discussed. The degradation mechanisms for the base resin, e.g., unstabilized Elvax 150^TM, and stabilized EVA are indicated for literature dating to the early 1950s, and the role played by unsaturated chromophores is indicated. The limited number of studies relating discoloration and PV cell efficiency are summarized.Observed degradation of EVA or the unstabilized base resin in the laboratory and examples used to measure the degradation are summarized in sections entitled: (1) thermally-induced degradation; (2) photodegradation and photothermal degradation of EVA in different temperature regimes; (3) photobleaching and photodegradation of the UV absorber and cross-linking agent; (4) acetic acid and metal and metal-oxide catalyzed oxidative degradation; and (5) discolaration and PV cell efficiency losses.Processing effects/influences on EVA stability are discussed in sections entitled: (1) EVA raw materials and extruded, uncured films; (2) thermal encapsulation processes; (3) effects of lamination, curing, and curing peroxide on gel content and chromophores formed; and (4) incomplete shielding of curing-generated chromophores. A summary is given for the limited number of accelerated lifetime testing efforts and examples of erroneous service lifetime predictions for EVA are discussed. The known factors that effect the discoloration rate of several EVA formulations are discussed in which the reduction in rate by using UV-absorbing superstrates is a prime example. A summary is given of what is and is not known about EVA degradation mechanisms, degradation from exposures in field-deployed modeules and/or laboratory testing, and factors that contribute to EVA stability or degradation. Finally, conclusions about using Elvax 150 in EVA formulations are summarized, and future prospects for developing the next-generation pottant for encapsulating PV modules are discussed.     

The material properties of sulphonated phenolic resin reinforced cement mortars

The material properties of new sulphonated phenolic resin (SP) reinforced cement mortars have been investigated. SP was found to promote the dispersion of cement particles and to interact with Ca(OH)₂. As a result, the resulting mortars exhibit better workability, more compact structure and higher compressive strength than plain mortars. The mortar with 1 wt% SP present after 28 days curing exhibits a compressive strength of 66MPa, which is about 18% higher than that of plain mortar.