Inductive electron-withdrawal from ammonium ion headgroups of cationic lipids and the influence on DNA transfection

We have prepared a panel of lipidic ammonium tetrafluoroborate salts that contain trifluoromethyl, trichloromethyl, and methyl groups attached to the headgroup. 19F-NMR analyses of the cationic lipid panel revealed that the differences in electron-withdrawal from the ammonium ion headgroup accounted for differences in ion-pairing. Exchange of the tetrafluoroborate counterion by complexation to DNA-phosphate of a reporter gene enabled us to probe the influence of inductive electron-withdrawal in cationic lipid-mediated DNA transfection. We tested the lipid panel for transfection activity in two cell lines. The results indicate that the inductive effects of electron-withdrawing functionality diminish transfection activity in modest (2-4-fold) increments. The present study suggests that the mechanism whereby poly(alcohol)- or poly(ether)-substituted headgroups improve DNA transfection is not based on electronic activation of the ammonium ion.     

Six-degrees-of-freedom alignment technique that provides diagnostic misalignment information

We introduce a new six-degrees-of-freedom alignment technique that enables the precise alignment of two optical device planes. The method combines linear diffraction gratings and cylindrical Fresnel lenses that allow the diagnosis of misalignment in each degree of freedom independently. The technique was used to align two 20 mm x 20 mm fused-silica substrates separated by 17 mm. The worst-case alignment precision was found to be better than +/- 5 microm laterally, +/- 20 microm longitudinally, +/- 0.036 degrees rotationally, and +/- 0.007degrees in tilt.     

Crambe seed processing: Decomposition of glucosinolates (thioglucosides) with chemical additives

Crambe meal was cooked with a variety of bases and metal salts to study decomposition of the undesirable glucosinolate (thioglucoside),epi-progoitrin. Salts of iron and copper were preferred because they were the most active decomposers and because they did not reduce the lysine content as did the alkalies. An unsaturated hydroxy nitrile, representing about 25 mole per cent of the decomposedepi-progoitrin, was the major reaction product left in the cooked meal. A thionamide product, representing about 7 mole per cent of the decomposedepi-progoitrin, was also observed in meals cooked with metallic salts. The thionamide was relatively unstable in moist, hot crambe meal, especially at basic pH, and may therefore be an intermediate in a complex decomposition path. Rats fed ferrous sulfate-treated crambe meal as 30% of a protein sufficient diet gained 70% compared with a basal control. Enlargement of thyroid, liver and kidneys was about 1.5 times that of the control organs. A crambe meal heated under the same conditions but without ferrous sulfate and fed at the same diet level caused 100% mortality within two weeks. Presented at AOCS Meeting, Houston, Texas, May 1971. Northern Marketing and Nutrition Research Division, ARS, USDA.     

Particle emission by fission

We have investigated the sputtering by fission fragments of Cu, Al and Nb doped with 0.1 at % ²³⁵U and bombarded with thermal neutrons. This was primarily a search for micron-size particles emitted from the surfaces of the doped sources. Kaminsky et al. have observed large particles (several microns in size) emitted from the surface of samples bombarded by 14 MeV neutrons, with a maximum knock-on energy of 600 keV in Nb. The fission energy deposition of 200 MeV should be more than adequate to yield any observable effects that might be present at 600 keV. The concentration of fission events was 10 times the concentration of primary knock-ons in the Kaminsky experiments. With scanning electron microscope and energy dispersive X-ray analyses of our sputtering collectors both before and after irradiation, we found no sputtered particles larger than our detection limit of 0.1 μm.     

Approximation schemes for a class of subset selection problems

In this paper we develop an easily applicable algorithmic technique/tool for developing approximation schemes for certain types of combinatorial optimization problems. Special cases that are covered by our result show up in many places in the literature. For every such special case, a particular rounding trick has been implemented in a slightly different way, with slightly different arguments, and with slightly different worst case estimations. Usually, the rounding procedure depended on certain upper or lower bounds on the optimal objective value that have to be justified in a separate argument. Our easily applied result unifies many of these results, and sometimes it even leads to a simpler proof.     

Lane selection in an AGV-based asynchronous parallel assembly line

Automated Guided Vehicles (AGVs) have the flexibility to meet the material handling requirements of asynchronous assembly lines. Furthermore, AGVs can select from among alternative paths in accordance with a prescribed lane selection rule, thereby facilitating the use of parallel server workstations.

In this paper, motivated by our work in the automotive industry, several new lane selection rules are proposed. One of these, First Available Server/First Available Buffer/Balanced Work Content (FAS/FAB/BWC), is compared to two existing rules: Alternating Server, and First Available Server/First Available Buffer/Expected Completion Time (FAS/FAB/EC). Three performance measures — job throughput, workload balance among servers, and alteration of input job sequence — are employed. A SIMAN simulation model of a small, asynchronous parallel assembly line is used to study the impact on system performance of both the lane selection rule and the number of parallel servers. Interaction between these two factors is studied through ANOVA. A number of interesting findings are reported for results of the lane selection rules with respect to the three performance measures. Their interpretation is used to motivate further research.     

The CTFA Evaluation of Alternatives Program: an evaluation of in vitro alternatives to the Draize primary eye irritation test. (Phase III) surfactant-based formulations

The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.     

Environmental aspects of the use of NTA as a detergent builder

The behaviour, fate and significance of the detergent builder nitrilotriacetic acid (NTA) has been reviewed with particular reference to the removal of NTA during wastewater treatment and the effects of NTA on heavy metal solubility both during treatment and in the receiving environment. It is concluded that NTA removal during secondary biological treatment is subject to considerable variation, both temporal and between works as a result of changes in NTA load, temperature, water hardness and treatment process parameters. As a result of such variability, effluent NTA concentrations may be sufficient to mobilise heavy metals resulting in metal contamination of receiving waters and potable waters, particularly in areas of low effluent dilution and high water re-use. Removal of NTA during primary sedimentation and septic tank treatment is concluded to be predominantly due to adsorption to the sludge solids while removal in anaerobic sludge digestion is subject to operational characteristics of the treatment works. Disposal of NTA contaminated sludge to land may contaminate groundwaters and affect heavy metal speciation, while the disposal of contaminated sludge or sewage to sea may result in toxic algal blooms, in addition to effects on metal speciation.