Vibrational spectra of crystalline polytetrafluoroethylene

Existing literature sources on the experimental vibrational spectroscopy of polytetrafluorethylene are reviewed and new detailed evidence in this field is presented. It has been proposed elsewhere on spectroscopic grounds that a structure exists involving two chains per unit cell at low temperatures, but X-ray support for this proposal is lacking. We explore this point in detail by referring to new spectroscopic data.     

Chain branching in high pressure polymerized polyethylene

We have combined the techniques of ¹³C nuclear magnetic resonance (n.m.r.) and nitric acid degradation to obtain information on the location of the side chains in branches polyethylene. Surprisingly, we have found that the ethyl and butyl groups are mainly excluded from the crystalline zones. The longer branches can cocrystallize with the main chain. Knowledge of the numbers and types of branch in polymers is of some technological important in polymer science. Short chain branching has a marked effect on the mechanical properties of the polymer, whilst the long chain branching affects the properties of melts.     

Anodische Korrosionsprozesse auf Stählen in inerten und in oxydierenden Atmosphären

Anodic corrosion processes on steels in inert and oxidising atmospheres The purpose of the investigation here described was to find out to what extent electrochemical techniques lend themselves to the examination of steel corrosion in the presence of molten sulphates and combustion gases. The measured equilibrium potentials of an inert metal electrode are intended to serve for the determination of the redox potential in the salt melt/combustion gases system. If no current is flowing, the stationary potential of a platinum electrode in a sulphate melt at 600° C can be expressed by the equation where E signifies the potential related to the silver/silver sulphate electrode, and p_SO2 p_O2 the partial pressures (in atmospheres) of the two gases in an inert gas (nitrogen + carbon dioxide). The formula permits the conclusion that the electrode reaction can be expressed by the equilibrium condition . The anode currents set up if the potential of a mild steel or pure iron electrode is kept at the above-mentioned temperature viz. ?0.3 V with N₂ + CO₂ + 5% O₂, or + 0.4 V with N₂ + CO₂ + 0.2% SO₂, show that under the test conditions, these metals would be greatly exposed to corrosion. Stainless steels become passive after a few hours although a residual corrosion current at + 0.4 V remains. These observations give rise to the expectation that electro-chemical examinations may well represent a useful means of examining corrosion phenomena caused by molten salts in the presence of combustion gases, so that they merit more detailed investigation.     

Teaching psychology by telephone.

2 groups of 10—matched for education, intelligence, and sex—participated. A special 8-weeks course in elementary psychology was presented. 1 of the 2 groups had face-to-face class meetings; the other group was taught by telephone. For the latter group: "In each home, an Executone speaker-microphone had been installed permitting everyone in the class to talk to everyone else as soon as the instructor turned on the switch… . Some lessons were straight lecture; others were conducted by discussion. Role playing was used twice." Both groups showed significant gains in knowledge as measured by examination. Both groups changed significantly in direction of more democratic attitudes as measured by the California F Scale. The "authors are now convinced that teaching by telephone is practical… . Telephone teaching might also be useful in areas of highly specialized instruction at the graduate level or in business or industry." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subliminal stimulation: An overview.

"Seldom has anything in psychology caused such an immediate and widespread stir as the recent claim that the presentation of certain stimuli below the level of conscious awareness can influence people's behavior in a significant way." Recent history relating to the technique is discussed under the topics of Recent Advertising Demonstrations, Research on Behavior without Awareness, and Effects of Inner States upon Thresholds. Unanswered Methodological Questions and The Ethics of Subliminal Influence are the other major topic areas. "The indiscriminate and uncontrolled application of psychological principles is increasing at a fearsome rate in the form of motivation research, propaganda, public relations, and a host of other useful practices based on the work of psychologists." Psychologists have a responsibility for assisting society to use its findings wisely. 132 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tribological behavior of a multialkylated cyclopentane oil under ultrahigh vacuum conditions

An ultrahigh vacuum, ball-on-flat test apparatus has been built to study the performance of candidate oils intended for spacecraft applications. Tests have been conducted on a multialkylated cyclopentane base oil using steel balls and disks. Different results are obtained when this oil is tested under vacuum conditions than when it is tested under a nitrogen environment. These differences are dramatic when the tests are conducted under starved conditions. Analyses of gases evolved during rubbing reveal that large quantities of methane are evolving from the process. A mechanism is proposed whereby oxide-free steel surfaces combine with tribological activity to crack the hydrocarbon oil to produce CH _x radicals. These CH _x radicals abstract hydrogen from the surrounding oil to produce methane. The increased volatility of the oil fragments remaining after methane formation leads to material loss by evaporation, thereby explaining the differences in vacuum and nitrogen performance of the oil.     

Towards Quantification of Functional Breast Images Using Dedicated SPECT With Non-Traditional Acquisition Trajectories

Quantification of radiotracer uptake in breast lesions can provide valuable information to physicians in deciding patient care or determining treatment efficacy. Physical processes (e.g., scatter, attenuation), detector/collimator characteristics, sampling and acquisition trajectories, and reconstruction artifacts contribute to an incorrect measurement of absolute tracer activity and distribution. For these experiments, a cylinder with three syringes of varying radioactivity concentration, and a fillable 800 mL breast with two lesion phantoms containing aqueous (99m)Tc pertechnetate were imaged using the SPECT sub-system of the dual-modality SPECT-CT dedicated breast scanner. SPECT images were collected using a compact CZT camera with various 3D acquisitions including vertical axis of rotation, 30° tilted, and complex sinusoidal trajectories. Different energy windows around the photopeak were quantitatively compared, along with appropriate scatter energy windows, to determine the best quantification accuracy after attenuation and dual-window scatter correction. Measured activity concentrations in the reconstructed images for syringes with greater than 10 μCi /mL corresponded to within 10% of the actual dose calibrator measured activity concentration for ±4% and ±8% photopeak energy windows. The same energy windows yielded lesion quantification results within 10% in the breast phantom as well. Results for the more complete complex sinsusoidal trajectory are similar to the simple vertical axis acquisition, and additionally allows both anterior chest wall sampling, no image distortion, and reasonably accurate quantification.     

A Measurement-Based Prioritization Scheme for Smartphone Applications

Applications labeled with priorities can reduce energy consumption on smartphones for network traffic, by conserving up to 56 % energy under typical usage patterns. In this paper, we present a measurement-based prioritization scheme for smartphone applications, which labels each application with a priority. More specifically, we first conduct a measurement of application usage on Android smartphones based on the implementation of SystemSens. Based on the measurement results, we observe that two key features of receiving rate (RX rate) and screen touch rate (ST rate) extracted from netlog and screen data can reflect the network interactivity and improve the accuracy of the prioritization scheme as well. Then, with the two selected features, we propose an online solution that prioritizes applications on smartphones to conserve energy consumption. Finally, we evaluate the proposed prioritization scheme with data from a user study, and the results demonstrate that our scheme can accurately prioritize applications on smartphones most of the time.     

Trichodermin Induces G0/G1 Cell Cycle Arrest by Inhibiting c-Myc in Ovarian Cancer Cells and Tumor Xenograft-Bearing Mice

Ovarian cancer is a fatal gynecological cancer because of a lack of early diagnosis, which often relapses as chemoresistant. Trichodermin, a trichothecene first isolated from Trichoderma viride, is an inhibitor of eukaryotic protein synthesis. However, whether trichodermin is able to suppress ovarian cancer or not was unclear. In this study, trichodermin (0.5 µM or greater) significantly decreased the proliferation of two ovarian cancer cell lines A2780/CP70 and OVCAR-3. Normal ovarian IOSE 346 cells were much less susceptible to trichodermin than the cancer cell lines. Trichodermin predominantly inhibited ovarian cancer cells by inducing G0/G1 cell cycle arrest rather than apoptosis. Trichodermin decreased the expression of cyclin D1, CDK4, CDK2, retinoblastoma protein, Cdc25A, and c-Myc but showed little effect on the expression of p21^Waf1/Cip1, p27^Kip1, or p16^Ink4a. c-Myc was a key target of trichodermin. Trichodermin regulated the expression of Cdc25A and its downstream proteins via c-Myc. Overexpression of c-Myc attenuated trichodermin’s anti-ovarian cancer activity. In addition, trichodermin decelerated tumor growth in BALB/c nude mice, proving its effectiveness in vivo. These findings suggested that trichodermin has the potential to contribute to the treatment of ovarian cancer.