Liquid-crystalline behaviour of some carboxylic acids

Summary A series of 4--carboxyalkoxyphenyl-4-methoxybenzoates 2 has been prepared. Compounds with a spacer length of n=3 and n=5 show liquid crystalline behaviour. The products were characterized by IR and ¹HNMR-spectroscopy, mass spectrometry, optical microscopy and DSC-measurements. The compounds are potentially useful as side-groups in liquid-crystalline polymers.     

A readout IC for an uncooled microbolometer infrared FPA with on-chip self-heating compensation in 0.35 μm CMOS

This paper describes a readout integrated circuit architecture for an infrared focal plane array intended for infrared network-attached video cameras in surveillance applications. The focal plane array consists of 352 × 288 uncooled thin-film microbolometer detectors with a pitch of 25 μm, enabling ambient temperature operation. The circuit features a low-noise readout path, detector resistance mismatch correction and a non-linear ramped current pulse scheme for the electrical biasing of the detectors in order to relax the dynamic range requirement of amplifiers and the ADC in the readout channel, imposed by detector process variation and self-heating during readout. The design is implemented in a 0.35-μm standard CMOS process and two versions of a smaller 32 × 32-pixel test chip have been fabricated and measured for evaluation. The latest test chip achieves a dynamic range of 97 dB and an input-referred RMS noise voltage of 6.4 μV yielding an estimated NETD value of 26 mK with f/1 optics. At a frame rate of 60 FPS the chip dissipates 170 mW of power from a 3.4 V supply.     

Design and testing of a high voltage coil for the kicker magnets ofCERN's Large Hadron Collider

A prototype LHC magnet has been built and tested at voltages of up to 35 kV. This paper describes the design of the high voltage excitation coil of the magnet, the different options for the coil insulation material and the adopted manufacturing process. It discusses the loss-factor measurements that have been carried out as part of the acceptance tests. Finally, it reports on endurance tests of the coil when it is mounted in the yoke and operated in a pulsed mode. The two dumping systems are furthermore used to remove the counter-rotating beams safely during the setting up of the accelerator and in case of emergencies. Reliable and accurate dumping is of prime importance. Uncontrolled beam losses will cause damage or destruction of adjacent superconducting magnets and will induce unacceptable heat losses in the cryogenic cooling system     

Structural changes in insulin-like growth factor (IGF) I mutant proteins affecting binding kinetic rates to IGF binding protein 1 and IGF-I receptor

Ligand binding properties of five single amino acid substituted variants (V11A, D12A, Q15A, Q15E, and F16A) of human insulin-like growth factor I (IGF-I) were analyzed with respect to their binding affinities and binding kinetics to recombinant IGF binding protein 1 (IGFBP-1) and a soluble form of the IGF type I receptor (sIGF-I(R)), respectively. Side chains of the substituted residues are all predicted to be the most surface exposed in the alpha-helical portion of the B-region of the IGF-I molecule. The IGF-I variants were produced as fusion proteins to a IgG(Fc) binding protein domain, Z. Ligand binding kinetic rates were determined using BIAcore biosensor interaction analysis technology. All IGF-I variants showed altered binding affinities to both IGFBP- I and sIGF-I(R). Secondary structure content of the IGF-I variants was estimated using far-UV circular dichroism spectroscopy, followed by variable selection secondary structure calculations. The amount of calculated alpha-helicity is reduced for all the mutants, most predominantly for IGF-I(V11A) and IGF-I(F16A) proteins. Surprisingly, most of the effects of reduced binding affinities to both target proteins are attributed to lowered on-rates of binding, and these are correlated with the amount of alpha-helicity in each IGF-I variant. In addition, in some of the IGF-I variants, lowered off-rates of binding are observed. From the results, we propose that IGF-I is unusually sensitive to structural changes by surface amino acid substitutions in the B-region of the molecule. Therefore, biochemical or biological properties of amino acid substituted variants of IGF-I cannot be used in a straightforward way to dissect the direct involvement in binding of individual amino acid residues since structural changes may be involved.     

Minimizing the risk of failure in a sheet metal forming process

In the present paper, an optimization technique has been used to minimize the risk of failure in a sheet metal forming process. Two different types of finite element solvers, one using total plasticity and the other using incremental plasticity, have been used. A comparison between response surface methodology and space mapping (SM) with the one-step solver as surrogate model has been done. The conclusion of this study is that the use of the total plasticity theory drastically reduces the required computing time. Furthermore, the solution from the SM optimization algorithm is close to the solution obtained by the incremental plasticity solver.     

Potassium, sodium, and cancer: a review

Agents known or believed to be carcinogenic decrease the concentration of potassium and increase the concentration of sodium in the cells. Anticarcinogenic agents have the opposite effect. In all cases where we have information on an agent's carcinogenicity or anticarcinogenicity and on that agent's effects on cellular potassium and sodium concentrations the above relationships have been found to be true. Dietary carcinogenic agents studied include sodium, cadmium, fat, cholesterol, calories, and alcohol; dietary anticarcinogenic agents include potassium, vitamins A, C, and D, selenium, and fiber. The effect of calcium intake is less clear as that effect depends on the concentrations on sodium and potassium. Not only dietary agents but also other carcinogenic and anticarcinogenic agents work in the same way. The cancer-causing drug dimethylhydrazine increases sodium and decreases potassium in the cells, whereas, for example, indomethacin, an anticarcinogen, has the opposite effect. In aging potassium leaves the cells, sodium enters them, and the rates of cancer increase. Patients with hyperkalemic diseases (Parkinson, Addison) have reduced cancer rates, and patients with hypokalemic diseases (alcoholism, obesity, stress) have increased cancer rates.     

Differences between and within genders in caregiving strain: a comparison between caregivers of demented and non-caregivers of non-demented elderly people

Fifty-two caregivers for demented and 66 non-caregivers for non-demented elderly were investigated both within a gender and between genders. All participants were relatives and a burden questionnaire was used. The results showed that there was not always a difference between the caregivers for demented and the non-caregivers for non-demented elderly which may indicate that being a relative, even to a non-demented elderly, has obviously its own problems and importance. However, results showed more significant differences between female caregivers and female non-caregivers than between male caregivers and male non-caregivers, with females caring for a demented elderly suffering most strain. Their strain was exhibited by health problems, conflicts in the family, strained relations with family and others, a less positive outlook and limits in social support because of the caregiving situation. When investigating the group of male caregivers and male non-caregivers, it was found that males caring for a demented elderly person experienced a lack of positive outlook and a need for social support. The elderly person's residence in the group of caregivers for demented elderly people and in the group of non-caregivers for non-demented elderly people did not, however, appear to indicate any significant differences.     

Reduced beta 2-microglobulin mRNA levels in transgenic mice expressing a designed hammerhead ribozyme

We have generated three artificial hammerhead ribozymes, denoted 'Rz-b', 'Rz-c' and 'Rz-d', with different specificities for exon II of the mouse beta-2-microglobulin (beta 2M) mRNA. In this study we tested for ribozyme mediated reduction of beta 2M mRNA in a cell line and in transgenic mice. Transfections of either of the Rz-b, Rz-c or Rz-d plasmids into a mouse cell-line (NIH/3T3) revealed reductions of beta 2M mRNA substrate in each case. Ribozyme expression in individual transfected clones was accompanied with an up to 80% reduction of beta 2M mRNA levels. Rz-c was selected for a transgenic study. Seven Rz-c transgenic founder animals were identified from which three ribozyme expressing families were established and analysed. Expression of the ribozyme transgene was tested for and detected in lung, kidney and spleen. Expression was accompanied with reduction of the beta 2M mRNA levels of heterozygous (Rz+/-) animals compared to non-transgenic litter mates. The effect was most pronounced in lung with more than 90% beta 2M mRNA reduction in individual mice. In summary, expression of our ribozymes in a cell free system, in a cell-line and in transgenic mice were all accompanied with reductions of beta 2M mRNA levels.     

Reduction of 2-nitropropane in an undivided,flooded, bipolar cell

As one model reaction in the study of the effect of contacting patterns on the overall specificity of electrosynthetic reactions, 2-nitropropane has been reduced to isopropylhydroxylamine and isopropylamine in an undivided, flooded, bipolar cell. Even though this cell was expected to be unfavourable for the overall reaction it was found that high space-time yields and current efficiencies could be obtained with a suitable choice of contacting pattern.     

Lectin studies of surface carbohydrates and induction of gland secretion in the free-living stages ofSchistosoma mansoni

Secretion from glands was observed when cercariae ofSchistosoma mansoni were exposed to certain lectins. Lectins fromMaclura pomifera, Pisum sativum, andTriticum vulgaris, were effective at 7.5 /ml. The effects of cercarial gland secretion caused byT. vulgaris agglutinin andArachis hypogaea agglutinin were blocked by pretreatment with the inhibiting glycan. Discharge of glands was not visualized after exposure of miracidia to lectins. The distribution of five labeled lectins was determined on live miracidia and cercariae. OnlyT. vulgaris agglutinin generally labeled the cercarial and miracidial bodies. Specific labeling occurred with the other lectins on the anterior, in glands or on their secretions, in flame cells in both stages, and on an unidentified ring of cells in miracidia. The possible mechanisms involved in changes caused by the lectins are discussed.