gebhart/patrepeval huggingface dataset:
Metallocene-mediated olefin polymerization : the effects of distal ligand perturbations on polymer stereochemistry (2004)

New group IV compounds containing a 9-dialkylaminofluorenide ligand have been prepared. Their properties and reactivity have been investigated. For example, single crystal X-ray analysis of the metallocene (9-(N,N-dimethylamino)fluorenyl)2ZrCl2 (4) reveals a bonding mode that includes a zirconium-nitrogen bond. In combination with methylaluminoxane (MAO), several aminofluorenide complexes afford atactic polypropylene. A statistical model has been developed that quantifies the unidirectional site epimerization probability, e, for singly- and doubly-bridged C1- symmetric metallocene polymerization catalysts. The unidirectional site epimerization model allows deconvolution of the site sequence probability and the stereochemical probability for producing a given pentad. Highly stereoregular syndiotactic polypropylene is obtained with the catalyst systems Ph2C(Oct)(C5H4)ZrCl2/MAO (8/MAO) (Oct = octamethyloctahydrodibenzofluorenyl, C-29H36) and Me2C(Oct)(C5H4)ZrCl2/MAO (12/MAO). Melting temperatures as high as 153?C or 154?C are found for the thermally quenched polymers. Distal ligand perturbations are demonstrated to have a dramatic effect on polymer stereochemistry. Polypropylenes that are isotactic-hemiisotactic or syndiotactic-hemiisotactic can be made with proper R substituent selection in the catalyst system Me2C(Flu)(3-R-C5H3)ZrCl2/MAO or Me2C(Oct)(3-R-C5H3)ZrCl2/MAO, where Flu = fluorenyl (C13H8). The prepared polymers have been subjected to a statistical model which suggests that the metallocenes have one highly selective site (99%) and one site of variable selectivity which is highly dependent on the nature of the R substituent and whether the metallocene contains the Flu or Oct ligand. Control of the tacticity of isotactic-hemiisotactic polypropylene, as quantified by the parameter a, is achieved by proper R substituent selection in the catalyst system R'2C(3-R-C5H3)(C13H8)MCl2/MAO. For R = 2-adamantyl, R' = Ph, and M = Zr or Hf, a is approximately 0.60 and the polypropylene obtained is elastomeric. Its properties are rationalized by the statistical existence of isotactic stereoblocks among an otherwise amorphous hemiisotactic medium. For the C1-symmetric polymerization catalyst Me2C(3-t-butyl-C5H3)(9-C13H8)ZrCl2/MAO, evidence gathered here supports an alternating mechanism in which both sites of the metallocene wedge are utilized for monomer insertion. For an Oct-containing catalyst system with a cyclopentadienyl substituent of R = 2-methyl-2-adamantyl, unprecedentedly high isotacticity (>99% [mmmm]) is observed for a fluorenyl-based metallocene catalyst. Melting temperatures for such isotactic polymers can be as high as 167?C (Tp = 0?C).
Direct Analyte‐Probed Nanoextraction Coupled to Nanospray Ionization–Mass Spectrometry of Drug Residues from Latent Fingerprints (2013)

Here, we present a method of extracting drug residues from fingerprints via Direct Analyte-Probed Nanoextraction coupled to nanospray ionization-mass spectrometry (DAPNe-NSI-MS). This instrumental technique provides higher selectivity and lower detection limits over current methods, greatly reducing sample preparation, and does not compromise the integrity of latent fingerprints. This coupled to Raman microscopy is an advantageous supplement for location and identification of trace particles. DAPNe uses a nanomanipulator for extraction and differing microscopies for localization of chemicals of interest. A capillary tip with solvent of choice is placed in a nanopositioner. The surface to be analyzed is placed under a microscope, and a particle of interest is located. Using a pressure injector, the solvent is injected onto the surface where it dissolves the analyte, and then extracted back into the capillary tip. The solution is then directly analyzed via NSI-MS. Analyses of caffeine, cocaine, crystal methamphetamine, and ecstasy have been performed successfully.
Generalized Walsh transforms of Boolean functions (2003)

A theoretical formulation of the generalized Walsh transform targeting different gate implementations is presented. The formulation is based on a uniform representation of completely and incompletely specified Boolean functions by a set of orthogonal and generalized Walsh spectral coefficients. The computer implementation drastically reduces required computation time by making it possible to calculate only chosen coefficients in specified polarity. The entire spectrum, if required, can be computed incrementally for groups of coefficients.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Multiphosphine‐Oxide Hosts for Ultralow‐Voltage‐Driven True‐Blue Thermally Activated Delayed Fluorescence Diodes with External Quantum Efficiency beyond 20% (2015)

Highly efficient low-voltage-driven -true-blue thermally activated -delayed fluorescence diodes are realized through employing a tri-phosphine oxide host (2,2',4-tris(di(phenyl) -phosphoryl)-diphenylether (DPETPO)) with a record external quantum efficiency of 23.0% and the lowest onset voltage of 2.8 V to date.
Handling a Dynamic Mixture of Sources in Blind Source Separation Tasks (2013)

We investigate an audio scene consisting of two main sound sources: (i) instrumental music and (ii) speech sound. To date, independent component analysis (ICA) has emerged as a powerful technique for blind source separation tasks. However, ICA does not handle a dynamic mixture of sources. In this paper, we investigate this issue and propose a two-pass framework: in the first pass, the system segments the mixed-source input into different chunks based on the similarity of the audio features, in the second pass, the system applies ICA to each segmented chunk. We argue that different mixtures of sources have different audio characteristics. These characteristics can be extracted using machine learning techniques. The extracted features are used to segment the mixed-source input into different chunks. Performing source separation on these chunks yields a better extraction of the original sources than performing a source separation without segmentation. We present the framework, experimental design and results from our proposed approach.
Intestinal Drug Absorption Enhancement by Aloe vera Gel and Whole Leaf Extract: In Vitro Investigations into the Mechanisms of Action (2019)

The co-administration of absorption enhancing agents with macromolecular drugs (e.g., protein and peptide drugs) has been identified as a means to improve the oral bioavailability of these drugs. Absorption-enhancing agents of natural origins have received a great deal of attention due to their sustainable production, in support of green chemistry. In previous studies, certain parts of the <i>Aloe vera</i> leaf (e.g., gel and whole leaf extract) have shown a potential to enhance drug permeation across the intestinal epithelial barrier. The mechanism of the drug-absorption-enhancement action and the capacity for absorption-enhancement of the <i>A. vera</i> gel and whole leaf, were investigated in this study. A clear decrease in transepithelial electrical resistance (TEER) of Caco-2 cell monolayers exposed to <i>A. vera</i> gel and wholeleaf extract, in various concentrations, indicated the opening of tight junctions between the epithelial cells. The transport of Fluorescein isothiocyanate (FITC)-dextran, with a molecular weight of 4 kDa (FD-4), could be enhanced across the Caco-2 cell monolayers, by the <i>A. vera</i> gel and whole-leaf extract, but not the FITC-dextran with larger molecular weights (i.e., 10, 20, and 40 kDa), which indicated a limited drug absorption enhancement capacity, in terms of the molecular size. Accumulation of FD-4 between the Caco-2 cells (and not within the cells), after treatment with the <i>A. vera</i> gel and whole-leaf extract was shown with a confocal laser scanning microscopy (CLSM) imaging, indicating that the paracellular transport of FD-4 occurred after the interaction of the <i>A. vera</i> gel and whole-leaf extract, with the epithelial cell monolayers. Furthermore, changes in the F-actin distribution in the cytoskeleton of the Caco-2 cell monolayers was observed by means of a fluorescence staining, which confirmed tight junction modulation as the mechanism of action for the absorption enhancement effect of the <i>A. vera</i> gel and whole-leaf extract.
Bacteriology of severe periodontitis in young adult humans (1982)

A total of 78 bacteriological samples were taken from the supragingival tooth surface after superficial cleaning with toothpicks or from the periodontal sulci of 42 affected sites in 21 adolescents or young adults with severe generalized periodontitis. Of 190 bacterial species, subspecies, or serotypes detected among 2,723 isolates, 11 species exceeded 1% of the subgingival flora and were most closely associated with the diseased sulci. Eleven others were also sufficiently frequent to be suspect agents of tissue destruction. Many of these species are known pathogens of other body sites. In addition, 10 species of Treponema were isolated. One of these and the "large treponeme" were also more closely associated with severe periodontitis than they were with healthy sites or gingivitis. There were highly significant differences between the composition of the flora of the affected sulci and the flora of (i) the adjacent supragingival tooth surface, (ii) the gingival crevice of periodontally healthy people, and (iii) sites with a gingival index score of 0 or 2 in experimental gingivitis studies. The floras of different individuals were also significantly different. There was no statistically detectable effect of sampling per se upon the composition of the flora of subsequent samples from the same sites. The composition of the supragingival flora of the patients with severe generalized periodontitis that had serum antibody to Actinobacillus actinomycetemcomitans was significantly different from the supragingival flora of patients without this serum antibody. However, there was no statistically significant difference in the composition of their subgingival floras.
Endocytosis by African trypanosomes. I. Three-dimensional structure of the endocytic organelles in Trypanosoma brucei and T. congolense. (1989)

African trypanosomes multiply rapidly during the course of infection obtaining nutrients from the host blood and other body fluids. The organelles involved in endocytosis were revealed ultrastructurally using horseradish peroxidase (HRP) and colloidal gold coupled to bovine transferrin (Au-Tf) or bovine serum albumin (Au-BSA). At 0 degree C the markers bound to the cell surface and neither entered the flagellar pocket nor were internalized. Upon warming to 37 degrees C, the markers were found in the flagellar pocket and appeared to enter all the intracellular endocytic organelles within 5 min. Serial sectioning of resin-embedded cells was employed to obtain pseudo three-dimensional views of these organelles. The organelles involved were of three types: (1) small vesicles and cisternae (20-25 nm in diameter), (2) large tubular networks (200 nm diameter) similar to endosomes of mammalian cells, and (3) large lysosome-like vesicles. These organelles were located between the flagellar pocket and the nucleus and were also associated with one face of the Golgi apparatus. In pulse-chase experiments HRP was not detected in intracellular organelles after 410 min but Au-Tf was seen in residual bodies. No exocytosis of Au-Tf from the flagellar pocket was observed. The data suggests that the processes of endocytosis in these parasitic protozoa may be similar to the endocytic processes found in mammalian cells.
Solution Structures and Molecular Interactions of Selective Melanocortin Receptor Antagonists (2010)

The solution structures and inter-molecular interaction of the cyclic melanocortin antagonists SHU9119, JKC363, HS014, and HS024 with receptor molecules have been determined by NMR spectroscopy and molecular modeling. While SHU9119 is known as a nonselective antagonist, JKC363, HS014, and HS024 are selective for the melanocortin subtype-4 receptor (MC4R) involved in modulation of food intake. Data from NMR and molecular dynamics suggest that the conformation of the Trp9 sidechain in the three MC4R-selective antagonists is quite different from that of SHU9119. This result strongly supports the concept that the spatial orientation of the hydrophobic aromatic residue is more important for determining selectivity than the presence of a basic, "arginine-like" moiety responsible for biological activity. We propose that the conformation of hydrophobic residues of MCR antagonists is critical for receptor-specific selectivity.
The biology of melanocytes (2003)

In veterinary medicine, our understanding of the biology and regulation of melanocytic function is mostly based on information realized from human and murine studies. Improved understanding of the biology of melanocytes is needed to develop more effective treatment regimens for malignant melanoma and other melanocytic disorders. In vertebrates, melanocytes are well known for their role in skin pigmentation, hair and feather coloration, and for their ability to produce and distribute melanin to surrounding keratinocytes. Enzymes involved in melanin synthesis are present exclusively in melanosomes. The type of melanin synthesized by melanocytes in mammals is regulated at a genetic, biochemical and environmental level. These regulatory factors affect not only the phenotypic appearance, but also the photoprotective properties of melanin. This review addresses the biology of melanocytes, melanin synthesis and the photoprotective properties of melanin.
Rate of Elongation of Polyphenylalanine <i>in vitro</i> (1982)

Ribosomes purified from Escherichia coli were preincubated with AcPhe-tRNA and poly(U). Then purified components necessary for polypeptide synthesis were added. Incubation of the complete system led to a burst of elongation which lasted for nearly 10 s. During the initial burst approximately 10% of the ribosomes participated in the elongation of poly(Phe) at an average rate per ribosome close to eight peptide bonds/s. The missense error rate with leucine was 4 x 10(-4) during the burst. Accordingly, the preincubated elongation system functions at a rate, as well as an accuracy, close to those of protein synthesis in vivo.
Transitive Invariance for Self-supervised Visual Representation Learning (2017)

Learning visual representations with self-supervised learning has become popular in computer vision. The idea is to design auxiliary tasks where labels are free to obtain. Most of these tasks end up providing data to learn specific kinds of invariance useful for recognition. In this paper, we propose to exploit different self-supervised approaches to learn representations invariant to (i) inter-instance variations (two objects in the same class should have similar features) and (ii) intra-instance variations (viewpoint, pose, deformations, illumination, etc). Instead of combining two approaches with multi-task learning, we argue to organize and reason the data with multiple variations. Specifically, we propose to generate a graph with millions of objects mined from hundreds of thousands of videos. The objects are connected by two types of edges which correspond to two types of invariance: "different instances but a similar viewpoint and category" and "different viewpoints of the same instance". By applying simple transitivity on the graph with these edges, we can obtain pairs of images exhibiting richer visual invariance. We use this data to train a Triplet-Siamese network with VGG16 as the base architecture and apply the learned representations to different recognition tasks. For object detection, we achieve 63.2% mAP on PASCAL VOC 2007 using Fast R-CNN (compare to 67.3% with ImageNet pre-training). For the challenging COCO dataset, our method is surprisingly close (23.5%) to the ImageNet-supervised counterpart (24.4%) using the Faster R-CNN framework. We also show that our network can perform significantly better than the ImageNet network in the surface normal estimation task.
Fulven (1964)

Abstract Fulvene has been prepared by condensing cyclopentadiene with formaldehyde at −15° using sodium ethylate as a base. UV.‐, IR.‐, NMR.‐ and mass spectra as well as polarographic half‐wave potentials have been recorded.
The optical transfer function of a perfect lens with polarisation masks (1978)

The optical transfer function (OTF) of a perfect lens with zonal masking of the lens aperture with polarisation devices has been studied. It is seen that the OTF of such system can be varied continuously by varying state of polarisation of the input beam and also by changing the orientation of the analyser placed at the output side.
Inferring the source of encrypted HTTP connections (2006)

We examine the effectiveness of two traffic analysis techniques for identifying encrypted HTTP streams. The techniques are based upon classification algorithms, identifying encrypted traffic on the basis of similarities to features in a library of known profiles. We show that these profiles need not be collected immediately before the encrypted stream; these methods can be used to identify traffic observed both well before and well after the library is created. We give evidence that these techniques will exhibit the scalability necessary to be effective on the Internet. We examine several methods of actively countering the techniques, and we find that such countermeasures are effective, but at a significant increase in the size of the traffic stream. Our claims are substantiated by experiments and simulation on over 400,000 traffic streams we collected from 2,000 distinct web sites during a two month period.
Protein incorporation by isolated amphibian oocytes III. Optimum incubation conditions (1973)

Abstract Available evidence indicates that protein incorporation by amphibian oocytes is mediated through a process of micropinocytosis. Oocytes incubated under our standard conditions sequester protein at a constant rate for at least 24 hours and appear to maintain approximately the same level of micropinocytosis as that observed in situ. Protein uptake is markedly sensitive to temperature and the ionic composition of the medium, with calcium being a particularly important component. Magnesium, phosphate, and additional energy sources are of only minor significance. Based on these observations, several slightly improved reformulations of the standard incubation medium are provided.
An analysis of the effects of feedline and ground screen noise currents on a conical monopole receiving antenna (1994)

Excessive electromagnetic interference/radio frequency interference (EMI/RFI) degrades the capability of the Naval Security Group (NSG) high frequency direction finding (HFDF) sites to receive signals of interest (SOI). These sites use a circularly disposed antenna array (CDAA) to receive signals in the 2 to 30 MHz frequency range. A conical monopole (CM), an antenna whose bandwidth matches the CDAA's, may provide a solution to the EMI/RFI problem through separation and isolation. Semi-remotely locating the CM away from EMI/ RFI sources achieves the former, while its independence from the noisy RF distribution system accomplishes the latter. This thesis analyzed the susceptibility of the CM to EMI/RFI currents that might be injected onto the feedline from equipment in the building at the center of the CDAA. The Numerical Electromagnetics Code (NEC) was used to model the CM and its buried feedline at the Imperial Beach CDAA site. The numerical model was used to validate proposed limits for the maximum allowable EMI/RFI current on incidental conductors and grounds at receiving sites. A maximum of two microamps of EMI current has been suggested to ensure that no appreciable degradation of SOI reception occurred. The NEC CM model predicted that the two microamp current limit would be adequate for SOI reception on the CM examined. Experimental measurements obtained at the Imperial Beach HFDF site partially validated these results and demonstrated that the CDAA response to the two microamp EMI/RFI limit is within the expected levels. Electromagnetic interference, EMI, Radio frequency interference, RFI, Circularly disposed antenna array, CDAA, Conical monopole antenna, Receiving sites.
Wireless Data Broadcast Schemes for Location-Dependent Information Services Under a Geometric Location Model (2005)

Indexing techniques are used to implement selective tuning in wireless environments. Indices are broadcast together with data to help mobile clients locate the required information. As a result, clients stay in doze mode most of the time. The drawback of this solution is that broadcast cycles are lengthened due to additional index information. In this paper, we introduce the broadcast-based LDIS scheme (BBS) for the mobile computing environment. In the BBS, broadcasted data objects are sorted sequentially, based on their location, and the server broadcasts the location-dependent data (LDD) without additional indices. Then, we present a data prefetching scheme and OBC (Object Boundary Circle) in order to reduce the client’s tuning time. The performance of the proposed scheme is investigated in relation to various environmental variables, such as the distributions of the data objects, the average speed of the clients, and the size of the service area.
Visual analysis of malware behavior using treemaps and thread graphs (2009)

We study techniques to visualize the behavior of malicious software (malware). Our aim is to help human analysts to quickly assess and classify the nature of a new malware sample. Our techniques are based on a parametrized abstraction of detailed behavioral reports automatically generated by sandbox environments. We then explore two visualization techniques: treemaps and thread graphs. We argue that both techniques can effectively support a human analyst (a) in detecting maliciousness of software, and (b) in classifying malicious behavior.
A Cartridge Type Pivotal Pin and Bushing Joint (1982)

<div class="htmlview paragraph">A cartridge type pivotal pin and bushing joint has been patented and is being tested and refined both in the laboratory and on construction machinery. It features “dry lubricated” (Teflon) bearings which are assembled and sealed prior to installation. It is suitable for heavy unit loads and use under severe wear conditions, such as in crawler track chains and loader bucket pivotal pin joints. A brief history of U. S. manufactured track pin joints is included to show the progress in extending the service life of these devices.</div>
Thermophilic bacterial isolates producing lipase (1987)

A number of lipase-producing thermophilic bacteria were isolated from natural habitats. One isolate, obtained from a coal tip sample, was examined in some detail: it was a highly thermophilic Bacillus sp. (optimum growth temperature approx. 65°C) and at 55°C it produced the maximum level of lipase (about 4 U/ml) in a medium containing Tween-80 (polyoxyethylene sorbitan monooleate) as the principal carbon source when growth had virtually ceased. Lipase synthesis thus appears to be inducible, and since a very low level of lipase was observed when the isolate was grown in a medium containing a carbon source like glucose as well as Tween-80, lipase synthesis is apparently also subject to catabolite repression.