gebhart/patrepeval huggingface dataset:
Effects of internal mineral structures on the magnetic remanence of silicate‐hosted titanomagnetite inclusions: An electron holography study (2006)

Titanomagnetite inclusions in pyroxene and plagioclase are carriers of stable magnetic remanence in some slowly cooled rocks such as gabbros, anorthosites, granulites, and diorites. Needle‐shaped inclusions with average dimensions of 1 × 1 × >25 μ m form epitaxially by exsolution from their host silicate. Close examination of clinopyroxene‐hosted inclusions reveals an internal microstructure, which consists of magnetite (Fe 3 O 4 ) prisms and ulvöspinel (Fe 2 TiO 4 ) lamellae that formed as a result of phase unmixing during initial cooling. This internal structure exerts a profound influence on the magnetic remanence properties of each inclusion, primarily by transforming it from a multidomain grain into an assemblage of magnetostatically interacting single‐domain prisms. Here we use off‐axis electron holography to image the magnetization states of individual prisms and the magnetostatic interactions between them. We show that the inclusions exhibit both single‐domain and collective magnetic states that depend primarily on the shape anisotropies of individual magnetite prisms, magnetostatic interactions between closely spaced prism stacks, and the shape anisotropy of the needle itself. Prisms that are separated by thick ulvöspinel lamellae show uniformly magnetized and/or vortex states. In contrast, closely spaced magnetite prisms behave as multipart vortices or as long composite columns, whose strong net magnetization may not be related directly to the orientation and shape of either the needle or the constituent prisms. The overall remanence direction recorded by clinopyroxene crystals containing finely exsolved inclusions is a reflection of both the inclusions' elongation directions and the prism arrangements within them.
Dielectric Properties of Lead Zirconate and Barium‐Lead Zirconate (1950)

Methods are described for preparing lead zirconate and mixtures of lead and barium zirconate in ceramic form. These compositions are shown to constitute a new class of ferroelectric materials having dielectric constants as high as 11,000. Dielectric constants are measured at 1 mc. per second in a temperature range 25° to 350° C. Nonlinear dielectric properties and piezoelectric effects are demonstrated.
Minimum constrast estimation with applications to array processing (1993)

Numerous studies have been devoted to performance analysis of direction of arrival (DOA) estimators in the context of narrow-band array processing. This contribution shows that the versatile concept of minimum contrast estimation provides a common unifying framework (i) to derive general conditions guaranteeing consistency and asymptotic normality of the estimators, (ii) to obtain closed form expressions for the asymptotic covariance of these estimators, and (iii) to develop practical numerical implementation of the estimators. The basic principles of minimum contrast estimation are reviewed. For brevity, the relevant results are stated without proof. These concepts are applied in the narrow-band array context. An application of this methodology is provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Spin–orbit splittings in Si/SiGe quantum wells: from ideal Si membranes to realistic heterostructures (2011)

We present a calculation of the wavevector-dependent subband level splitting from spin–orbit coupling in Si/SiGe quantum wells. We first use the effective-mass approach, where the splittings are parameterized by separating contributions from the Rashba and Dresselhaus terms. We then determine the inversion asymmetry parameters by fitting tight-binding numerical results obtained using the quantitative nanoelectronic modeling tool, NEMO-3D. We describe the relevant coefficients as a function of applied electric field and well width in our numerical simulations. Symmetry arguments can also predict the behavior, and an extensive analysis is also presented in this work. Using vast computational resources, we treat alloy disorder at the atomistic scale. We obtain first-time results for realistic Si/SiGe heterostructures. Our numerical data are in very good agreement with experimental results, both qualitatively and quantitatively. We conclude that effects of alloy disorder have a crucial influence on the spin–orbit parameters.
Efficacy of Remission-Induction Regimens for ANCA-Associated Vasculitis (2013)

In patients with severe ANCA-associated vasculitis, a single course of rituximab was as effective as continuous conventional immunosuppressive therapy for the induction and maintenance of remissions over the course of 18 months. (Funded by the National Institute of Allergy and Infectious Diseases and others; RAVE ClinicalTrials.gov number, NCT00104299.)
A Regularly Structured 54-bit Modified-Wallace-Tree Multiplier. (1991)

1 Conditions have been worked out for a reliable estimation of the cataleptic activity of delta'-trans-tetrahydrocannabinol (THC) after oral administration to mice, using the ring test over a period of 6 h. 2 By this method, the activity of cannabis herb and 5 crude fractions were measured against THC; at the same time the THC contents were determined chemically. 3 The B/C ratio (biological activity divided by chemical assay) was calculated for each. With cannabis herb the value was 3.3 and with extracts prepared with ethanol or 70% ethanol the values ranged from 3.2 to 7.1, indicating that in all samples the activity was much higher than would be expected from their THC content. 4. The cannabinoids were completely extracted from a sample of herb using petroleum spirit and the marc examined for a possible synergist. Surprisingly, it contained a powerful inhibitor of the action of THC, which could be restored by intraperitoneal prostaglandin E2 (3 microgram/kg). Some crude fractions had inhibitory activities about 10 times that of aspirin. 5 In contrast, the petroleum spirit extract (referred to in 4) had a surprisingly high B/C ratio of 23, indicating that a powerful synergist of THC activity is present. 6 The net effect of the herb and ethanol extracts is probably due to a balance of synergist and inhibitor.
Prediction of Glycosylphosphatidylinositol-Anchored Proteins in Arabidopsis. A Genomic Analysis (2002)

Glycosylphosphatidylinositol (GPI) anchoring of proteins provides a potential mechanism for targeting to the plant plasma membrane and cell wall. However, relatively few such proteins have been identified. Here, we develop a procedure for database analysis to identify GPI-anchored proteins (GAP) based on their possession of common features. In a comprehensive search of the annotated Arabidopsis genome, we identified 167 novel putative GAP in addition to the 43 previously described candidates. Many of these 210 proteins show similarity to characterized cell surface proteins. The predicted GAP include homologs of beta-1,3-glucanases (16), metallo- and aspartyl proteases (13), glycerophosphodiesterases (6), phytocyanins (25), multi-copper oxidases (2), extensins (6), plasma membrane receptors (19), and lipid-transfer-proteins (18). Classical arabinogalactan (AG) proteins (13), AG peptides (9), fasciclin-like proteins (20), COBRA and 10 homologs, and novel potential signaling peptides that we name GAPEPs (8) were also identified. A further 34 proteins of unknown function were predicted to be GPI anchored. A surprising finding was that over 40% of the proteins identified here have probable AG glycosylation modules, suggesting that AG glycosylation of cell surface proteins is widespread. This analysis shows that GPI anchoring is likely to be a major modification in plants that is used to target a specific subset of proteins to the cell surface for extracellular matrix remodeling and signaling.
Stimulation of human neutrophils with formyl-methionyl-leucyl-phenylalanine induces tyrosine phosphorylation and activation of two distinct mitogen-activated protein-kinases (1993)

Stimulation of human polymorphonuclear neutrophils with the chemotactic peptide FMLP induces an increase in the phosphorylation of several proteins on tyrosine residues. Immunoblotting of whole cell lysates with antiphosphotyrosine antibodies demonstrated this increase to be predominant in two proteins with apparent m.w. of 40,000 and 42,000, respectively. We identify these two proteins as members of the mitogen-activated-protein (MAP) kinase family. These results are based on comigration of the tyrosine phosphorylated proteins with two proteins of same apparent m.w., recognized by a series of antibodies raised against sequences contained within members of this family. This was further confirmed by immunoprecipitation with either an antiphosphotyrosine antibody or a MAP kinase-specific antibody. To assess whether neutrophil stimulation with FMLP increased MAP kinase activity, the cells were stimulated with various doses of FMLP and the phosphotransferase activity in cell lysates was measured against two identified substrates of MAP kinase: myelin basic protein and T-669, the epidermal growth factor receptor Thr 669 synthetic peptide modeled after the major site of phosphorylation of the receptor. A dose- and time-dependent increase in MAP kinase activity was detected in the lysates from FMLP-stimulated PMN, which closely correlated with the dose and time course of tyrosine phosphorylation of the 40- and 42-kDa proteins. Additionally, the MAP kinases in crude lysates were enriched by DEAE-cellulose chromatography and further resolved on a MonoQ column by fast performance liquid chromatography. The respective eluates contained the two proteins, each recognized by anti-MAP kinase antibodies and, after stimulation, each was phosphorylated on tyrosine residues and expressed T-669 phosphotransferase activity. Treatment with genistein, a tyrosine kinase inhibitor, reduced the tyrosine phosphorylation of the 40- and 42-kDa proteins in a dose-dependent manner, decreased the activation of the MAP kinases, and inhibited the production of superoxide anion by FMLP-stimulated neutrophils. Therefore, this study demonstrates that human polymorphonuclear neutrophils contain two distinct members of the MAP kinase family, antigenically related to sea star p44mpk and rat p43erk1 and that both MAP kinase isoforms are implicated in the cascade of protein phosphorylation induced by neutrophil stimulation with FMLP. Furthermore, these data suggest that tyrosine phosphorylation and activation of these two enzymes may play a regulatory role in the signal transduction pathway leading to the respiratory burst induced by FMLP.
Laser-induced microscopic etching of GaAs and InP (1980)

Ultraviolet laser photolysis of methyl-halides has been used to produce localized photoetching of GaAs and InP. A spatial resolution of ≃1μm has been achieved and an etch rate ≳104 times that of the dark reaction demonstrated. A chemical mechanism is proposed and the observed resolution is explained by a simple physical model.
Role of purinergic receptor polymorphisms in human bone (2011)

Osteoporosis is a multifactorial disease with a strong genetic component. Variations in a number of genes have been shown to associate with bone turnover and risk of osteoporosis. P2 purinergic receptors are proteins that have ATP or other nucleotides as their natural ligands. Various P2Y and P2X receptor subtypes have been identified on bone cells. Several cellular functions in bone tissue are coupled to P2-receptor activation, including bone resorption, cytokine release, apoptosis, bone formation, and mineral deposition. Furthermore, ATP release and P2 purinergic signalling is a key pathway in the mechanotransductory process, where mechanical stimulation on bone leads to anabolic responses in the skeleton. A number of single nucleotide polymorphisms have been identified in the P2 receptor genes, where especially the P2X7 subtype has been the focus of extensive investigation where several polymorphisms have been shown to have functional implications on receptor function; moreover, some polymorphisms are associated with alterations in bone turnover and bone mass. This review focuses on variations in P2 receptor genes and the association to bone turnover and -quality.
Flux driven fly throughs (2003)

We present a fast, robust and automatic method for computing central paths through tubular structures for application to virtual endoscopy. The key idea is to utilize a medial surface algorithm, which exploits properties of the average outward flux of the gradient vector field of a Euclidean distance function the boundary of the structure of interest. The algorithm is modified to yield a collection of 3D curves, each of which is locally centered. The approach requires no user interaction, and is virtually parameter free and has low computational complexity. We illustrate the approach on segmented colon and vessel data.
Acridine-psoralen amines and their interaction with deoxyribonucleic acid (1983)

A series of novel compounds in which a 9-acridinyl nucleus is linked to a psoralen nucleus in the 5- or 8-position via polyamines was prepared and examined. Their reversible binding to DNA and their irreversible binding to DNA and DNA cross-linking upon irradiation with UV-A light were examined. It was found that they were all less efficiently photoreactive than 8-methoxypsoralen (8-MOP), both in cross-linking and photobinding to DNA, whereas the ratio between their photobinding and cross-linking was 40-400 times that of 8-MOP. Compounds in which the linker was attached to the 5-position in psoralen showed smaller cross-linking and photobinding efficiencies and larger ratios between photobinding and cross-linking than those of psoralens attached in the 8-position. This strongly indicates that the 9-substituents of the acridines are oriented toward the minor groove. Flow linear dichroism studies showed that the compounds were DNA intercalating with the acridine moiety, whereas the psoralen moiety in no case was clearly intercalating. This conclusion was further supported by viscometry which also strongly indicated monointercalation.
Effects of Methylphenidate on Cognitive Function and Gait in Patients With Parkinson's Disease (2006)

Twenty-one patients with Parkinson's disease were studied before and 2 h after the administration of a single dose of 20 mg of methylphenidate. In response to methylphenidate, attention significantly improved, whereas memory and visual-spatial performance were unchanged. Gait speed, stride time variability, and Timed Up and Go times (demonstrated measures of fall risk) significantly improved. These findings suggest a new potential pharmacologic means of enhancing mobility and decreasing fall risk in Parkinson's disease.
Pyrrole aus 3-Alkoxyacroleinen und CH-aciden α-Aminoessigsäure-Derivaten (1989)

Pyrroles from 3-Alkoxyacroleins and CH-acidic α-Aminoacetic Acid Derivatives 2-Alkoxycarbonylpyrroles and 2-cyanopyrroles 4 are prepared in a one-step synthesis by vinylogous amidation of 3-alkoxyacroleins 1 with glycine ester 2a-c and aminoacetonitrile (2d), followed by basecatalyzed cyclodehydration of the intermediate 3-aminoacroleins 3. The 3-hydroxypropyl function can be introduced into the pyrrole ring by using 3,4-dihyrdo-2H-pyran-5-carbaldehyde (5) as a cyclic 3-alkoxyacrolein.
The Dehydro-Diels−Alder Reaction (2008)

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTThe Dehydro-Diels−Alder ReactionPablo Wessig* and Gunnar MüllerView Author Information Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany* Author to whom correspondence may be addressed. E-mail: [email protected]Cite this: Chem. Rev. 2008, 108, 6, 2051–2063Publication Date (Web):May 15, 2008Publication History Received21 January 2008Published online15 May 2008Published inissue 1 June 2008https://pubs.acs.org/doi/10.1021/cr0783986https://doi.org/10.1021/cr0783986review-articleACS PublicationsCopyright © 2008 American Chemical SocietyRequest reuse permissionsArticle Views12279Altmetric-Citations322LEARN 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 SUBJECTS:Addition reactions,Aromatic compounds,Cyclization,Hydrocarbons,Photochemical reactions Get e-Alerts
Reaction modes of fluorination of cyclic ethers by potassium fluoride-18-crown-6 (1980)

ADVERTISEMENT RETURN TO ISSUEPREVArticleReaction modes of fluorination of cyclic ethers by potassium fluoride-18-crown-6Yuhsuke Kawakami and Yuya YamashitaCite this: J. Org. Chem. 1980, 45, 19, 3930–3932Publication Date (Print):September 1, 1980Publication History Published online1 May 2002Published inissue 1 September 1980https://pubs.acs.org/doi/10.1021/jo01307a047https://doi.org/10.1021/jo01307a047research-articleACS PublicationsRequest reuse permissionsArticle Views732Altmetric-Citations9LEARN 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
Role of methionine in the regulation of the synthesis of serine hydroxymethyltransferase in Escherichia coli. (1984)

The synthesis of serine hydroxymethyltransferase during methionine limitation is different in met A and met B auxotrophs, mutants defective in homocysteine biosynthesis, as compared to met E and met F auxotrophs, mutants which are unable to methylate homocysteine and thus unable to either synthesize methionine de novo or to regenerate it after use via methylation reactions. Methods for the measurement of intracellular concentrations of sulfur-containing amino acids and nucleosides were developed and applied to cultures of the methionine auxotrophs. No definitive correlation between the absolute intracellular concentration of any single metabolite and the rate of serine hydroxymethyltransferase synthesis was found. However, a high correlation (0.92) was found with the ratio of homocysteine to S-adenosylmethionine, with the rate of enzyme synthesis being a hyperbolic function of the ratio. This is consistent with homocysteine acting as an inducer and S-adenosylmethionine as a corepressor of serine hydroxymethyltransferase synthesis with high affinity for a repressor molecule. This correlation holds only during methionine limitation, and was not observed during glucose limitation or in unrestricted cultures with added adenosine.
Naıve and Memory CD4 T Cells Differ in Their Susceptibilities to Human Immunodeficiency Virus Type 1 Infection following CD28 Costimulation: Implications for Transmission and Pathogenesis (1998)

In vitro evidence suggests that memory CD4(+) cells are preferentially infected by human immunodeficiency virus type 1 (HIV-1), yet studies of HIV-1-infected individuals have failed to detect preferential memory cell depletion. To explore this paradox, we stimulated CD45RA+ CD4(+) (naïve) and CD45RO+ CD4(+) (memory) cells with antibodies to CD3 and CD28 and infected them with either CCR5-dependent (R5) or CXCR4-dependent (X4) HIV-1 isolates. Naïve CD4(+) cells supported less X4 HIV replication than their memory counterparts. However, naïve cells were susceptible to R5 viral infection, while memory cells remained resistant to infection and viral replication. As with the unseparated cells, mixing the naïve and memory cells prior to infection resulted in cells resistant to R5 infection and highly susceptible to X4 infection. While both naïve and memory CD4(+) subsets downregulated CCR5 expression in response to CD28 costimulation, only the memory cells produced high levels of the beta-chemokines RANTES, MIP-1alpha, and MIP-1beta upon stimulation. Neutralization of these beta-chemokines rendered memory CD4(+) cells highly sensitive to infection with R5 HIV-1 isolates, indicating that downregulation of CCR5 is not sufficient to mediate complete protection from CCR5 strains of HIV-1. These results indicate that susceptibility to R5 HIV-1 isolates is determined not only by the level of CCR5 expression but also by the balance of CCR5 expression and beta-chemokine production. Furthermore, our results suggest a model of HIV-1 transmission and pathogenesis in which naïve rather than memory CD4(+) T cells serve as the targets for early rounds of HIV-1 replication.
Architectural Chemistry: Synthesis of Topologically Diverse Macromulticycles by Sequential Multiple Multicomponent Macrocyclizations (2009)

How can conformationally restricted polyvalent molecules be accessed rapidly? A sequential approach involving two multiple multicomponent macrocyclizations including bifunctional building blocks (MiBs) with up to five Ugi-four-component reactions (Ugi-4CR) has been developed to produce nonsymmetric macromulticycles. Topologically diverse structures, such as nonsymmetric cryptands and clam- and igloo-shaped macromulticycles were obtained in reaction sequences that comprise the incorporation of up to 13 building blocks by forming 20 new bonds without purification of intermediates. Cryptands were produced by a sequential-MiB procedure in which the Ugi-type functional groups of the second MiB are attached to the peptoid backbones from the first multicomponent macrocyclization. These macrobicycles show two completely new features; i.e., three different tether chains can be obtained in one pot, and tertiary amide bonds are used as bridgeheads. Alternatively, the same reaction sequence, i.e., MiB/deprotection/MiB, can be used to produce clam-shaped macrobicycles, demonstrated with a tetrafunctional cholanic steroid as a hinge moiety. Macrotetracycles endowed with igloo-type topologies are accessible by an advanced protocol featuring consecutive double and 3-fold Ugi-4CR-based macrocyclizations. Other building blocks than cholanic steroids employed include aryl, heterocyclic, polyether, and other recognition motifs. The examples given are a first-generation demonstration of an "architectural chemistry" that allows to construct three-dimensional multimotif covalent molecular "buildings" of unprecedented complexity by design.
Carbon-coated copper nanoparticles: synthesis, characterization and optical properties (2009)

Carbon-coated copper (C/Cu) nanoparticles with a size of 50–80 nm were synthesized through a simple solid-state reduction reaction. The reaction process and optical properties were subsequently explored.