Mapping High-Temperature Superconductors—A Scientometric Approach

This study has been carried out to analyze the research field of high-temperature superconductivity and to demonstrate the potential of modern databases and search systems for generating meta-information. The alkaline earth (A2) rare earth (RE) cuprate high-temperature superconductors as a typical inorganic compound family and the corresponding literature were analyzed by scientometric methods. The time dependent overall number of articles and patents and of the publications related to specific compound subsets and subject categories are given. The data reveal a significant decrease of basic research activity in this research field. The A2 RE cuprate species covered by the CAS compound file were analyzed with respect to the occurrence of specific elements in order to visualize known and unknown substances and to identify characteristic patterns. The quaternary and quinternary cuprates were selected and the number of compound species as a function of specific combinations of A2 and RE elements is given. The Cu/O and RE/A2 ratios of the quaternary cuprate species as a function of A2 and RE atoms are shown. In addition, the research landscape of the MgB₂ related publications was established using STN AnaVist, an analysis tool recently developed by STN International.     

Temporal analyses of virus replication, immune responses, and efficacy in rhesus macaques immunized with a live, attenuated simian immunodeficiency virus vaccine

Despite evidence that live, attenuated simian immunodeficiency virus (SIV) vaccines can elicit potent protection against pathogenic SIV infection, detailed information on the replication kinetics of attenuated SIV in vivo is lacking. In this study, we measured SIV RNA in the plasma of 16 adult rhesus macaques immunized with a live, attenuated strain of SIV (SIVmac239Deltanef). To evaluate the relationship between replication of the vaccine virus and the onset of protection, four animals per group were challenged with pathogenic SIVmac251 at either 5, 10, 15, or 25 weeks after immunization. SIVmac239Deltanef replicated efficiently in the immunized macaques in the first few weeks after inoculation. SIV RNA was detected in the plasma of all animals by day 7 after inoculation, and peak levels of viremia (10(5) to 10(7) RNA copies/ml) occurred by 7 to 12 days. Following challenge, SIVmac251 was detected in all of the four animals challenged at 5 weeks, in two of four challenged at 10 weeks, in none of four challenged at 15 weeks, and one of four challenged at 25 weeks. One animal immunized with SIVmac239Deltanef and challenged at 10 weeks had evidence of disease progression in the absence of detectable SIVmac251. Although complete protection was not achieved at 5 weeks, a transient reduction in viremia (approximately 100-fold) occurred in the immunized macaques early after challenge compared to the nonimmunized controls. Two weeks after challenge, SIV RNA was also reduced in the lymph nodes of all immunized macaques compared with control animals. Taken together, these results indicate that host responses capable of reducing the viral load in plasma and lymph nodes were induced as early as 5 weeks after immunization with SIVmac239Deltanef, while more potent protection developed between 10 and 15 weeks. In further experiments, we found that resistance to SIVmac251 infection did not correlate with the presence of antibodies to SIV gp130 and p27 antigens and was achieved in the absence of significant neutralizing activity against the primary SIVmac251 challenge stock.     

6‐Substituted 2‐Aminopurine‐2′‐deoxyribonucleoside 5′‐Triphosphates that Trace Cytosine Methylation

Gene expression is extensively regulated by the occurrence and distribution of the epigenetic marker 2′‐deoxy 5‐methylcytosine (5mC) in genomic DNA. Because of its effects on tumorigenesis there is an important link to human health. In addition, detection of 5mC can serve as an outstanding biomarker for diagnostics as well as for disease therapy. Our previous studies have already shown that, by processing O⁶‐alkylated 2′‐deoxyguanosine triphosphate (dGTP) analogues, DNA polymerases are able to sense the presence of a single 5mC unit in a template. Here we present the synthesis and evaluation of an extended toolbox of 6‐substituted 2‐aminopurine‐2′‐deoxyribonucleoside 5′‐triphosphates modified at position 6 with various functionalities. We found that sensing of 5‐methylation by this class of nucleotides is more general, not being restricted to O⁶‐alkyl modification of dGTP but also applying to other functionalities.     

Monocyte-dependent death of freshly isolated T lymphocytes: induction by phorbolester and mitogens and differential effects of catalase

Resting T cells are resistant to anti-Fas (CD95) mAb-mediated apoptosis but undergo apoptosis when triggered by anti-CD3 mAb or phorbolester PMA in the presence of PMA-activated monocytes. In this study, PMA, as well as the mitogens PHA and Con A, was found to induce death of resting T cells in the presence of autologous or allogeneic monocytes, while PWM was ineffective. Although several established monocytic and myelocytic cell lines were potent accessory cells for the mitogen-induced expansion of T lymphocytes, they all failed to replace plastic-adherent monocytes in the induction of monocyte-dependent cell death (MDCD) by PMA or PHA. CD45RA-positive cord blood T cells were as susceptible as peripheral blood T cells from adult donors to PMA-stimulated induction of MDCD. Using optimal concentrations of phorbolester, MDCD was inhibited neither by Fas-Fc fusion protein or neutralizing anti-Fas mAb, nor by inhibitors of IL-1beta-converting enzyme (ICE)-like proteases. In striking contrast, the H2O2 scavenger catalase completely prevented the PMA-stimulated T cell death, thereby revealing a potent mitogenic activity of PMA for human T cells in the presence of monocytes. Taken together, our results demonstrate that the accessory cell activity of monocytes/macrophages can be separated into "T cell death" and "T cell expansion" costimulatory functions, of which only the latter is mediated by established cell lines. Moreover, our results point to a pivotal role of reactive oxygen intermediates in the execution of MDCD triggered by PMA.     

Diffusion of Aroma Compounds into Packaging Films under High Pressure

Diffusion of the aroma compounds p-cymene and acetophenone into three different packaging films was studied at 500 MPa for kinetic measurement, and in the range of 0.1–450 MPa for measurement of the diffusion rate as a function of pressure. Absorption of aroma compounds was lower in pressurized than in nonpressurized polymeric films. PET/A1/LDPE was impermeable to either substance; absorption was limited to the LDPE lining inside. Distribution of aroma compounds to solution and films depended on their polarity; acetophenone virtually did not diffuse into the films. Measurements of the diffusion rate as a function of pressure has shown a diffusion barrier in the range of 100–200 MPa for the films investigated. The assumption that this is due to transition into the glassy state has been supported by studies of diffusion as a function of temperature.     

Nitroprusside and methylene blue methods for silicone membrane differentiated flow injection determination of sulfide in water and wastewater.

Hydrogen sulfide evolved from an acidified sample is pre-concentrated by permeation in a stationary alkaline acceptor solution enclosed in a silicone rubber sample loop. Depending on the sample volume pre-concentrated, the applicable analytical range spans low micrograms/L to tens of mg/L for both methods. The methylene blue method is more sensitive by a factor of approximately 30 and actually permits practical determinations in the sub-micrograms/L levels. The limit of detection (LOD) for the nitroprusside method ranges from 20 micrograms/L for a 20 microL sample by conventional flow-injection determination (no membrane, throughput 30 samples/h) to less than 2 micrograms/L for 12 mL sample pre-concentrated in the membrane system (throughput 5 samples/h). The membrane is highly resistant to fouling and permits analysis of untreated wastewater samples bearing suspended solids, oil, grease, etc. without any pretreatment. No significant interference is observed with either chemistry. Although the nitroprusside chemistry is less sensitive, it does not involve the use of concentrated aggressive reagents and is recommended unless ultratrace determinations are essential. Viable reaction mechanisms are proposed for both of these chemistries.     

How accurately does Thomas Kuhn’s model of paradigm change describe the transition from the static view of the universe to the big bang theory in cosmology?

Up to the 1960s the prevalent view of science was that it was a step-by-step undertaking in slow, piecemeal progression towards truth. Thomas Kuhn argued against this view and claimed that science always follows this pattern: after a phase of “normal” science, a scientific “revolution” occurs. Taking as a case study the transition from the static view of the universe to the Big Bang theory in cosmology, we appraised Kuhn’s theoretical approach by conducting a historical reconstruction and a citation analysis. As the results show, the transition in cosmology can be linked to many different persons, publications, and points in time. The findings indicate that there was not one (short term) scientific revolution in cosmology but instead a paradigm shift that progressed as a slow, piecemeal process.