gebhart/patrepeval huggingface dataset:
Optically pumped atomic magnetometers after three decades (1992)

The main achievements in the development of optically pumped atomic magnetometers are reviewed. The best up-to-date magnetometers have sensitivities up to 0.1 pT/(Hz)<sup>1/2</sup> and absolute accuracy of about 0.1 nT, permitting notless than 10 readings per 1 s. The main applications are earth field gradiometry and variometry.
Radio-frequency glow discharge ion trap mass spectrometry (1992)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRadio-frequency glow discharge ion trap mass spectrometryScott A. McLuckey, Gary L. Glish, Douglas C. Duckworth, and R. Kenneth. MarcusCite this: Anal. Chem. 1992, 64, 14, 1606–1609Publication Date (Print):July 15, 1992Publication History Published online1 May 2002Published inissue 15 July 1992https://pubs.acs.org/doi/10.1021/ac00038a018https://doi.org/10.1021/ac00038a018research-articleACS PublicationsRequest reuse permissionsArticle Views218Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Site-controlled and advanced epitaxial Ge/Si quantum dots: fabrication, properties, and applications (2017)

In this review, we report on fabrication paths, challenges, and emerging solutions to integrate group-IV epitaxial quantum dots (QDs) as active light emitters into the existing standard Si technology. Their potential as laser gain material for the use of optical intra- and inter-chip interconnects as well as possibilities to combine a single-photon-source-based quantum cryptographic means with Si technology will be discussed. We propose that the mandatory addressability of the light emitters can be achieved by a combination of organized QD growth assisted by templated self-assembly, and advanced inter-QD defect engineering to boost the optical emissivity of group-IV QDs at room-temperature. Those two main parts, the site-controlled growth and the light emission enhancement in QDs through the introduction of single defects build the main body of the review. This leads us to a roadmap for the necessary further development of this emerging field of CMOS-compatible group-IV QD light emitters for on-chip applications.
Infrared‐Emitting Colloidal Nanocrystals: Synthesis, Assembly, Spectroscopy, and Applications (2007)

Semiconductor nanocrystals produced by means of colloidal chemistry in a solvent medium are an attractive class of nanometer-sized building blocks from which to create complex materials with unique properties for a variety of applications. Their optical and electronic properties can be tailored easily, both by their chemical composition and particle size. While colloidal nanocrystals emitting in the infrared region have seen a burst of attention during the last decade there is clearly a paucity of review articles covering their synthesis, assembly, spectroscopic characterization, and applications. This Review comprehensively addresses these topics for II-VI, III-V, and IV-VI nanocrystals, examples being HgTe and Cd(x)Hg(1-) (x)Te, InP and InAs, and PbS, PbSe, and PbTe, respectively. Among the applications discussed here are optical amplifier media for telecommunications systems, electroluminescence devices, and noninvasive optical imaging in biology.
Suppressed transformation and induced differentiation of HER-2/neu-overexpressing breast cancer cells by emodin. (1995)

The amplification and overexpression of the HER-2/neu proto-oncogene, which encodes the tyrosine kinase receptor p185neu, have been observed frequently in tumors from human breast cancer patients and are correlated with poor prognosis. To explore the potential of chemotherapy directed at the tyrosine kinase of p185neu, we have found that emodin (3-methyl-1,6,8-trihydroxyanthraquinone), a tyrosine kinase inhibitor, suppresses autophosphorylation and transphosphorylation activities of HER-2/neu tyrosine kinase, resulting in tyrosine hypophosphorylation of p185neu in HER-2/neu-overexpressing breast cancer cells. Emodin, at a 40-microM concentration, which repressed tyrosine kinase of p185neu, efficiently inhibited both anchorage-dependent and anchorage-independent growth of HER-2/neu-overexpressing breast cancer cells. However, the inhibition was much less effective for those cells expressing basal levels of p185neu under the same conditions. Emodin also induced differentiation of HER-2/neu-overexpressing breast cancer cells by exhibiting a morphological maturation property of large lacy nuclei surrounded by sizable flat cytoplasm and by showing a measurable production of large lipid droplets, which is a marker of mature breast cells. Therefore, our results indicate that emodin inhibits HER-2/neu tyrosine kinase activity and preferentially suppresses growth and induces differentiation of HER-2/neu-overexpressing cancer cells. These results may have chemotherapeutic implications for using emodin to target HER-2/neu-overexpressing cancer cells.
Ion‐Exchange Chromatography (1999)

This unit outlines the basic steps in planning and carrying out ion-exchange chromatography to separate proteins. Protocols describe both batch adsorption and column chromatography in conjunction with either step- or linear elution gradients. Support protocols describe (1) pilot experiments to determine initial conditions for batch or column chromatography (i.e., pH required for binding, change in pH or salt concentration required for elution, and available capacity of a medium), (2) calculation of the dynamic capacity of an ion-exchange column, (3) methods for producing continuous gradients of pH and salt concentration to elute proteins from ion-exchange columns, (4) regeneration of used ion-exchange media, and (5) storage of ion-exchange media.
Lithium aluminium hydride-aluminium chloride reduction of steroidal cyclic acetals (1971)

Lithium aluminium hydride-aluminium chloride (1 : 1, AlH2Cl) reduction of 3,3-ethylenedioxycholest-5-ene (5), 3,3-ethylenedioxy-5a-oholestane (7), 6,6-ethyl-enedioxy-5a-cholestane (7), and 3,3-(1?- methylethylenedioxy)cholest-5-en (8a), gave the glycol ethers (9), (17), (21a), and (24), respectively. The structures of the ethers (9), (17), (21a), and (24) have been established by their spectral properties and chemical transformations. A mechanism of the hydrogenolysis is presented.
SYNTHESIS OF A PRECURSOR TRIPEPTIDE Z-Asp-Val-Tyr-OH OF THYMOPENTIN BY CHEMO-ENZYMATIC METHOD (2012)

The precursor tripeptide of thymopentin was synthesized by a combination of chemical and enzymatic methods. First, Val-Tyr-OH dipeptide was synthesized by a novel chemical method in two steps involving preparation of NCA-Val. Second, the linkage of the third amino acid Z-Asp-OMe to Val-Tyr-OH was completed by an enzymatic method under kinetic control. An industrial alkaline protease alcalase was used in water-organic cosolvent systems. The synthesis reaction conditions were optimized by examining the effects of several factors including organic solvents, water content, temperature, pH, and reaction time on the yield of Z-Asp-Val-Tyr-OH. The optimum condition is of pH 10.0, 35°C, acetonitrile/Na₂CO₃-NaHCO₃ buffer system (85:15, v/v), and reaction time of 2.5 hr, which achieves tripeptide yield of more than 70%.
The initial step of DNA hairpin folding: a kinetic analysis using fluorescence correlation spectroscopy (2006)

Conformational fluctuations of single-stranded DNA (ssDNA) oligonucleotides were studied in aqueous solution by monitoring contact-induced fluorescence quenching of the oxazine fluorophore MR121 by intrinsic guanosine residues (dG). We applied fluorescence correlation spectroscopy as well as steady-state and time-resolved fluorescence spectroscopy to analyze kinetics of DNA hairpin folding. We first characterized the reporter system by investigating bimolecular quenching interactions between MR121 and guanosine monophosphate in aqueous solution estimating rate constants, efficiency and stability for formation of quenched complexes. We then studied the kinetics of complex formation between MR121 and dG residues site-specifically incorporated in DNA hairpins. To uncover the initial steps of DNA hairpin folding we investigated complex formation in ssDNA carrying one or two complementary base pairs (dC-dG pairs) that could hybridize to form a short stem. Our data show that incorporation of a single dC-dG pair leads to non-exponential decays for opening and closing kinetics and reduces rate constants by one to two orders of magnitude. We found positive activation enthalpies independent of the number of dC-dG pairs. These results imply that the rate limiting step of DNA hairpin folding is not determined by loop dynamics, or by mismatches in the stem, but rather by interactions between stem and loop nucleotides.
Roles of Glycogen Synthase Kinase 3 in Alzheimer’s Disease (2012)

Evidence from basic molecular biology has noted a critical role of GSK-3 in Alzheimer's disease (AD) pathogenesis such as beta-amyloid (Aβ) production and accumulation, the formation of neurofibrillary tangle (NFT), and neuronal degeneration. Aβ generation and deposition represents a key feature and is generated from APP by the sequential actions of two proteolytic enzymes: β-secretase and γ-secretase. GSK-3 could play a critical role in Aβ production via enhancing β-secretase activity. GSK-3 not only modulates APP processing in the process of Aβ generation, but regulates Aβ production by interfering with APP cleavage at the γ-secretase complex step since the APP and PS1 (a component of γ- secretase complex) are substrates of GSK-3 as well. GSK-3 may downregulate α-secretase through inhibiting PKC and ADAMs activity which are the substrates of GSK-3 contributing to Aβ production. Meanwhile, Aβ accumulation can induce GSK-3 activation through Aβ-mediated neuroinflammation and oxidative stress. Considering that active GSK-3 and some common GSK-3-shared factors induce the hyperphosphorylation of tau and neurofibrillary lesions, GSK-3 is a possible linking between amyloid plaques and NFT pathology. Additionally, GSK-3 could disrupt acetylcholine activity, and accelerate axon degeneration and failures in axonal transport, and lead to cognitive impairment in AD. Preclinical and clinical studies have supported that GSK-3β inhibitors could be useful in the treatment of AD. Consequently, an effective measure to inhibit GSK-3 activity may be a very attractive drug target in AD.
Experimental realization of a Mode-locked parabolic Raman fiber oscillator (2010)

We report here the first demonstration of a mode-locked fiber laser delivering parabolic pulses (similaritons) at 1534 nm. The use of a Raman-based gain medium potentially allows its implementation at any wavelength. The 22nJ output similariton pulses have a true parabolic shape both in the time and spectral domains and a linear chirp. Linear recompression close to Fourier limit is demonstrated allowing us to obtain 6 ps compressed pulses with a compression factor of 75.
Control allocation for fault tolerant control of a VTOL octorotor (2012)

For the fault tolerant control of an eight-rotor VTOL Unmanned Air Vehicle (UAV), a control allocation scheme is proposed. The eight-rotor configuration provides actuator redundancy to ensure safe operation under rotor/motor failures. A PD controller is used to generate total thrust and moment demands. A cascade inverse method of control allocation is proposed to allocate the controller commands to the actuators whilst ensuring that actuator saturation does not occur. If the vehicle is subjected to rotor failures, the scheme re-allocates the commands to maintain the vehicle stability and performance. Until actuator saturation occurs the response of the vehicle is the same when operating with all motors or fewer. The response of the vehicle to several combinations of complete actuator failures is investigated by simulation and it is shown that the proposed method is able to maintain control after failure of up to four actuators. The controller is invarient and the vehicle response to commands is identical until motor saturation occurs.
Characterization of poly(<scp>L</scp>‐lactic acid) fibers produced by melt spinning (2001)

Abstract Biodegradable poly( L ‐lactic acid) (PLLA) fibers were processed by a two‐step melt‐spinning method (melt extrusion and hot draw) from PLLA with three different viscosity‐average molecular weights (494,600, 304,700, and 262,800). Before spinning, the polymer flakes were first milled into powders and dried under vacuum. Viscosity‐average molecular weight of PLLA following the fabrication process was monitored. Tensile properties of as‐spun and hot‐drawn fibers were investigated. Morphology of the PLLA fibers was viewed under a scanning electron microscope. Crystallinity of these fibers was assessed by thermogram analysis of differential scanning calorimetry. Results showed that the extent of decrease in the viscosity‐average molecular weight of PLLA dropped sharply by 13.1–19.5% during pulverization and by 39.0–69.0% during melt‐extrusion. The hot‐draw process in this study had a little effect on the viscosity‐average molecular weight of PLLA. Smoother fibers could be obtained for the die temperature at least 230°C for raw materials with higher crystallinity (more than 75%) and at least 220°C for raw materials with lower crystallinity (about 60%). The as‐spun fibers showed crystallinity of 16.5–22.8% and the value increased to 50.3–63.7% after hot draw. Tensile moduli of the as‐spun fibers were in the range of 1.2–2.4 GPa, which were raised to 3.6–5.4 GPa after hot draw. The final PLLA fibers with 110–160 μm diameters showed tensile strengths of 300–600 MPa. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 251–260, 2001
Severely Reduced Female Fertility in CD9-Deficient Mice (2000)

CD9 is a widely expressed cell surface molecule that belongs to the tetraspanin superfamily of proteins. The tetraspanins CD9, KAI-1/CD82, and CD63 are involved in metastasis suppression, an effect that may be related to their association with beta1 integrins. Knockout mice lacking CD9 were created to evaluate the physiological importance of CD9. CD9-/- females displayed a severe reduction of fertility. Oocytes were ovulated but were not successfully fertilized because sperm did not fuse with the oocytes from CD9-/- females. Thus, CD9 appears to be essential for sperm-egg fusion, a process involving the CD9-associated integrin alpha6beta1.
How cellular processing of superparamagnetic nanoparticles affects their magnetic behavior and NMR relaxivity (2012)

Cellular processing of nanomaterials may affect their physical properties at the root of various biomedical applications. When nanoparticles interact with living cells, their spatial distribution is progressively modified by cellular activity, which tends to concentrate them into intracellular compartments, changing in turn their responsivity to physical stimuli. In this paper, we investigate the consequences of cellular uptake on the related magnetic properties and NMR relaxivity of iron oxide nanoparticles. The superparamagnetic behavior (field-dependent and temperature-dependent magnetization curves investigated by SQUID (Superconducting Quantum Interference Device) measurements) and nuclear magnetic relaxation dispersion (NMRD) R(1) profiles of citrate-coated maghemite nanoparticles (mean diameter 8 nm) were characterized in colloidal suspension and after being uptaken by several types of cells (tumor cells, stem cells and macrophages). The temperature-dependent magnetization as well as the NMRD profile were changed following cellular uptake depending on the stage of endocytosis process while the field-dependent magnetization at room temperature remained unchanged. Magnetic coupling between nanoparticles confined in cell lysosomes accounts for the modification in magnetic behavior, thereby reflecting the local organization of nanoparticles. NMR longitudinal relaxivity was directly sensitive to the intracellular distribution of nanoparticles, in line with Transmission Electron Microscopy TEM observations. This study is the first attempt to link up magnetic properties and NMR characterization of iron oxide nanoparticles before and after their cell processing.
Horn Image Guide Leaky-Wave Antenna (2005)

A novel approach for designing a frequency-scanning millimeter-wave antenna is described. The antenna is constructed by using an image wide leaky-wave antenna embedded in a long trough with metal flares along both sides. The optimum flare angle for achieving maximum gain is theoretically predicted. The design of the leaky-wave antenna, which is comprised of metallic-strip perturbations on top of a dielectric guide, is also discussed.
Degradation of Human Fibrinogen by Plasma α2-Macroglobulin-Enzyme Complexes (1973)

This study demonstrates that human plasma alpha(2)-macroglobulin preparations possess an enzymic activity that degrades fibrinogen, resulting in the formation of products whose structure resembles that of circulating fibrinogen catabolites. The sequence of degradation is similar to that observed in plasmin-catalyzed digests, in that Aalpha-chain fragmentation precedes that of Bbeta-chain. The addition of plasminogen activators to plasma induced an increase in the N-alpha-tosyl-l-arginine methyl ester HCl esterase and fibrinogenolytic activity associated with alpha(2)-macroglobulin purified from this plasma, indicating that the enzymic activity of the complex was preserved and could be increased in the presence of other plasma enzyme inhibitors. Immunochemical studies demonstrated that an alpha(2)-macroglobulin-plasmin complex had formed in urokinase-treated plasma. This alpha(2)-macroglobulin preparation manifested an esterolytic profile like that of a complex prepared from plasmin and purified alpha(2)-macroglobulin. After complex formation with alpha(2)-macroglobulin in plasma, plasmin retained less than 0.1% of its fibrinogenolytic activity. That plasmin expressed its activity while bound to alpha(2)-macroglobulin was suggested by immunoprecipitation of this activity with alpha(2)-macroglobulin antibody and by the demonstration that pancreatic trypsin inhibitor did not effectively inhibit its fibrinogenolytic or esterolytic activity. These results raise the possibility that, in addition to its activity as a major plasma proteolytic enzyme inhibitor, alpha(2)-macroglobulin may modulate enzyme-substrate interactions, such as those resulting in the formation of circulating fibrinogen catabolites, by providing a mechanism for the preservation and protection of a portion of the enzymic activity in the presence of other circulating inhibitors.
Leukotriene A4 hydrolase: protection from mechanism-based inactivation by mutation of tyrosine-378. (1996)

Leukotriene A4 (LTA4) hydrolase [(7E,9E,11Z,14Z)-(5S,6S)-5,6-epoxyicosa-7, 9,11,14-tetraenoate hydrolase; EC 3.3.2.6] is a bifunctional zinc metalloenzyme that catalyzes the final step in the biosynthesis of the potent chemotactic agent leukotriene B4 (LTB4). LTA4 hydrolase/aminopeptidase is suicide inactivated during catalysis via an apparently mechanism-based irreversible binding of LTA4 to the protein in a 1:1 stoichiometry. Previously, we have identified a henicosapeptide, encompassing residues Leu-365 to Lys-385 in human LTA4 hydrolase, which contains a site involved in the covalent binding of LTA4 to the native enzyme. To investigate the role of Tyr-378, a potential candidate for this binding site, we exchanged Tyr for Phe or Gln in two separate mutants. In addition, each of two adjacent and potentially reactive residues, Ser-379 and Ser-380, were exchanged for Ala. The mutated enzymes were expressed as (His)6-tagged fusion proteins in Escherichia coli, purified to apparent homogeneity, and characterized. Enzyme activity determinations and differential peptide mapping, before and after repeated exposure to LTA4, revealed that wild-type enzyme and the mutants [S379A] and [S380A]LTA4hydrolase were equally susceptible to suicide inactivation whereas the mutants in position 378 were no longer inactivated or covalently modified by LTA4. Furthermore, in [Y378F]LTA4 hydrolase, the value of kcat for epoxide hydrolysis was increased 2.5-fold over that of the wild-type enzyme. Thus, by a single-point mutation in LTA4 hydrolase, catalysis and covalent modification/inactivation have been dissociated, yielding an enzyme with increased turnover and resistance to mechanism-based inactivation.
Ground surface segmentation for navigation with a low resolution visual prosthesis (2011)

We propose the use of ground surface segmentation to enhance the perception of obstacles in low to medium resolution prosthetic visual representations. We apply a recently proposed algorithm for segmenting traversable space in stereo disparity data, and show how such a scheme may be utilised to enhance the distinction between the ground surface and obstructions (in particular, small trip hazards). Qualitative comparisons with intensity and straight depth-based representations highlight advantages for the visualisation of obstacles, offering potential gains for visual navigation with low resolution and low dynamic range visual prostheses.
Promising therapeutic targets for antileishmanial drugs (2002)

Current treatments for the parasitic disease leishmaniasis are unsatisfactory due to their route of administration, toxicity and expense. Resistance is also developing to first-line antimonial drugs. Fortunately, a handful of antileishmanial agents, such as the orally available compound miltefosine, are currently in clinical trials. In addition, several promising drug targets and lead molecules are being studied with the goal of developing new antileishmanial agents. Drug candidates have been identified through the continued investigation of parasite sterol metabolism and parasite proteases. New antileishmanial molecules have also been discovered through the study of novel targets and pathways, such as the bisphosphonate inhibitors of isoprenoid biosynthesis. This review presents a synopsis of the drug targets and lead compounds that have been investigated over the last few years against leishmaniasis, gives a perspective on the chemotherapeutic potential of each and discusses some of the obstacles to antileishmanial drug development.