gebhart/patrepeval huggingface dataset:
Fluorescent core-shell silica nanoparticles: an alternative radiative materials platform (2006)

We report on monodisperse fluorescent core-shell silica nanoparticles (C dots) with enhanced brightness and photostability as compared to parent free dye in aqueous solution. Dots containing either tetramethylrhodamine or 7-nitrobenz-2-oxa-1,3-diazole dyes with diameters ranging from tens of nanometers to microns are discussed. The benefits of the core-shell architecture are described in terms of enhanced fluorescent yield of the fluorophores in the quasi-solid-state environment within the particle as compared with parent free dye in water. Several applications of these particles in the fields of photonics and the life sciences are discussed. Specifically, fluorescent core-shell silica nanoparticles are investigated as an active medium for photonic building blocks assembled on zinc sulfide-based seed particles. Initial assembly results for these composite raspberry structures are shown. Finally, applications in the life sciences are explored, including targeting of specific antibody receptors using these single-emission nanoparticles. We expand on single-emission core-shell architecture to incorporate environmentally-sensitive fluorophores to create quantitative ratiometric nanoscale sensors capable of interrogating chemical concentrations on the sub-cellular to molecular levels and demonstrate initial results of intracellular pH imaging. The concept of a single particle laboratory (SPL) is introduced as an active investigator of its environment.
Nature and origin of asphaltenes in processed coals. Annual report. [55 references] (1976)

Several significant new methods of study were developed. These included a novel fractionation procedure for the separation of soluble coal products into discrete chemical classes. With this chemical description of the Solvent Refined Coal (SRC) products, fundamental understanding of the mechanisms involved in coal conversion can be achieved and a chemical basis for process optimization may possibly be found. Procedures were also developed which allowed the study of the transformation of coal to soluble form under the conditions of pressure and temperature common to SRC processing, but at very short times (as short as 15 to 30 sec.). A synthetic solvent developed and used in this project is composed of a minimum number of known low boiling compounds that reflect the chemistry of actual recycle solvents. This solvent was easily separated and distinguished from coal products and, because of its simplicity, the chemistry of solvent-solvent and solvent-coal interactions could also be determined. The key findings of this work using these new tools are described in detail.
End-member extraction based on segmented vertex component analysis in hyperspectral images (2017)

Hyperspectral images collected by a remote sensing hyperspectral imaging instrument have many mixed pixels, due to the limited resolution of image sensors and the complex diversity of nature. End-member extraction is the process that determines the end-members in mixed pixels. The results of traditional methods are inaccurate, due to the spatial complexity and noise of actual hyperspectral image data. This study presents segmented vertex component analysis (SVCA), wherein the relative complexities of hyperspectral images are segmented into a number of relatively simple spatial subsets to reduce the effect of uncorrelated pixels. The end-members are extracted by finding the vertices of the simplex that minimally encloses the hyperspectral image data in each spatial subset, and the inversion abundance is used to identify each major end-member in each subset. Experimental results demonstrate that the proposed method can effectively implement end-member extraction with high accuracy.
Scintillator with ZnWO/sub 4/ single crystal (1982)

A scintillator formed of a ZnWO/sub 4/ single crystal having an absorption coefficient less than or equal to 1.8 cm-1 for the light having a wavelength of 520 nm is disclosed which has a luminescence wavelength of 480 nm and therefore can be combined with a photodiode, and which is high in radiation detection sensitivity, short in decay time, and specifically suitable for use in computed tomography.
Expedited-compact architecture for average scan power reduction (2012)

In expedited-compact scan, the output response of the STUMPS channels is smartly compacted without the overhead of the full-scan chain-shift operation, thereby reducing the scan mode power. The authors propose suitable integration with other scan compression methods.
A new approach to prepare well‐dispersed CaF<sub>2</sub> nanoparticles by spray drying technique (2011)

Previously, nano-sized calcium fluoride (CaF₂) particles were prepared using a spray drying method by simultaneously feeding Ca(OH)₂ and NH₄F solutions to a two-liquid nozzle. The aim of the present study was to prepare better-dispersed nano-CaF₂ particles by co-forming a soluble salt, sodium chloride (NaCl). NaCl of various concentrations were added to the NH(4) F solution, leading to formation of (CaF₂ +NaCl) composites with CaF₂ /NaCl molar ratios of 4/1, 4/4, and 4/16. Pure nano-CaF₂ was also prepared as the control. Powder X-ray diffraction analysis showed that the products contained crystalline CaF₂ and NaCl. Scanning electron microscopy examinations showed that both the CaF₂ /NaCl composite and pure CaF₂ particles were about (50-800) nm in size and consisted of primary CaF₂ particles of < 50 nm in size. BET surface area measurements showed similar primary particle sizes for all samples. Dynamic light scattering measurements showed that the washed (CaF₂+NaCl) particles were much smaller than the pure CaF₂ as the dissolution of NaCl "freed" most of the primary CaF₂ particles, leading to a greater degree of particle dispersion. The well-dispersed nano-CaF₂ may be expected to be a more effective anticaries agent than NaF by providing longer lasting elevations of fluoride concentrations in oral fluids.
Retargeting the Clostridium botulinum C2 toxin to the neuronal cytosol (2016)

Many biological toxins are known to attack specific cell types, delivering their enzymatic payloads to the cytosol. This process can be manipulated by molecular engineering of chimeric toxins. Using toxins with naturally unlinked components as a starting point is advantageous because it allows for the development of payloads separately from the binding/translocation components. Here the Clostridium botulinum C2 binding/translocation domain was retargeted to neural cell populations by deleting its non-specific binding domain and replacing it with a C. botulinum neurotoxin binding domain. This fusion protein was used to deliver fluorescently labeled payloads to Neuro-2a cells. Intracellular delivery was quantified by flow cytometry and found to be dependent on artificial enrichment of cells with the polysialoganglioside receptor GT1b. Visualization by confocal microscopy showed a dissociation of payloads from the early endosome indicating translocation of the chimeric toxin. The natural Clostridium botulinum C2 toxin was then delivered to human glioblastoma A172 and synchronized HeLa cells. In the presence of the fusion protein, native cytosolic enzymatic activity of the enzyme was observed and found to be GT1b-dependent. This retargeted toxin may enable delivery of therapeutics to peripheral neurons and be of use in addressing experimental questions about neural physiology.
ATM Kinase Is Required for Telomere Elongation in Mouse and Human Cells (2015)

Short telomeres induce a DNA damage response, senescence, and apoptosis, thus maintaining telomere length equilibrium is essential for cell viability. Telomerase addition of telomere repeats is tightly regulated in cells. To probe pathways that regulate telomere addition, we developed the ADDIT assay to measure new telomere addition at a single telomere in vivo. Sequence analysis showed telomerase-specific addition of repeats onto a new telomere occurred in just 48 hr. Using the ADDIT assay, we found that ATM is required for addition of new repeats onto telomeres in mouse cells. Evaluation of bulk telomeres, in both human and mouse cells, showed that blocking ATM inhibited telomere elongation. Finally, the activation of ATM through the inhibition of PARP1 resulted in increased telomere elongation, supporting the central role of the ATM pathway in regulating telomere addition. Understanding this role of ATM may yield new areas for possible therapeutic intervention in telomere-mediated disease.
Enzyme conversion immunoassay for determining total homocysteine in plasma or serum (1998)

A rapid and precise immunoassay for quantification of total homocysteine in blood samples is presented. The method avoids the use of radioisotopes and chromatographic separations and relies on enzymatic conversion of homocysteine to S-adenosyl-L-homocysteine, followed by quantification of S-adenosyl-L-homocysteine by an enzyme-linked immunoassay in microtiter format. The within- and between-assay imprecision is < 6% and 8%, respectively, and results by the method show good correlation with those by HPLC. Including controls and calibrators in duplicates, 82 samples can be analyzed within 2.5 h. The procedure can be fully automated.
An electromagnetic microscope for eddy current evaluation of materials (1991)

The concept for a novel instrument to be used in nondestructive evaluation (NDE) is presented. It is called an electromagnetic microscope, formed by superconductive microprobes arrayed in parallel rows. When moved over a test piece, the array generates a scanned image of flaws, stress variations, or changes in composition. Each microprobe comprises drive coils a few millimeters in radius that encircle pickup loops forming a concentric superconducting quantum interference device (SQUID). Drive coils transmit an oscillating magnetic field that induces eddy or magnetization currents in conductive or ferromagnetic materials, respectively. The gradiometer senses distortions in paths of induced currents. The extreme sensitivity of SQUIDS increases sensitivity, penetration depth, and spatial resolution over existing eddy current and magnetic NDE systems. Estimates of performance predict that a current of 1 A oscillating at 1 kHz in the drive coils allows detection of a flaw 0.1-mm in diameter to a depth of several millimeters in aluminum, with a horizontal resolution of about 1 mm and a vertical resolution of 0.3 mm or so.
Positioning of Functionalities in a Heteroduplex Major Groove: Synthesis of 7-Deaza-2-Amino-2′-deoxyadenosines (1997)

Abstract We have synthesized the 7-iodo-, 7-cyano-and 7-propynyl-7-deaza-2-ainino-2′-deoxyadenosines and incorporated each into several oligonucleotide (ODN) sequences. These oligonucleotides exhibit enhanced binding affinities to RNA complements relative to unmodified sequences.
Materials for Liquid Crystal Displays with Reduced Power Consumption (2000)

Abstract A significant reduction of the power consumption of a liquid crystal display can be achieved either by application of a lower driving voltage or – even more effectively – by use of a holographically structured reflective scattering type of display without colour filters. The first option requires strongly polar materials with extremely high reliability, the second one new types of liquid crystals with a birefringence as high as possible in order to optimize the scattering effect. A molecular modeling based method for the prediction of reliability parameters is presented.
Use of ultrasound in monitoring chemical contamination in water (1995)

The US Environmental Protection Agency (EPA) has been examining the potential of combining sonication with other technologies for monitoring specific classes of organic pollutants in water. Pollutants are decomposed into ions which can be detected using known electrochemical techniques. An increase in concentration of the target ion after sonication indicates the presence of the pollutant. This paper presents additional results on the use of sonochemistry in monitoring carbon tetrachloride (CCl{sub 4}), chloroform (CHCl{sub 3}), and Cl{sub 2}CCHCl (trichloroethylene)(TCE) in water. Relationships were examined for changes in chloride ion and pH upon sonication versus concentration of the individual organochlorine pollutants. Another issue deals with the effect of various humic acids (at different concentrations) on changes in Cl{sup {minus}}, pH, and conductivity, as a result of sonicating solutions of the pollutants. Linear relationships with excellent correlation coefficients were found between increases of Cl{sup {minus}} (after sonication) and 3--80 ppm concentrations of CCl{sub 4}, CHCl{sub 3}, and TCE in water. The pH was found to decrease in all cases, and the relationships were nonlinear. Three different humic acids were examined in concentrations up to 400 ppm for effects on Cl{sup {minus}} yield, pH changes, and conductivity changes. There were no differences in Cl{supmore » {minus}} yield relative to control solutions of chlorinated hydrocarbons in deionized water. However, conductivity and pH changes were much smaller.« less
Multiple human D5 dopamine receptor genes: a functional receptor and two pseudogenes. (1991)

Three genes closely related to the D1 dopamine receptor were identified in the human genome. One of the genes lacks introns and encodes a functional human dopamine receptor, D5, whose deduced amino acid sequence is 49% identical to that of the human D1 receptor. Compared with the human D1 dopamine receptor, the D5 receptor displayed a higher affinity for dopamine and was able to stimulate a biphasic rather than a monophasic intracellular accumulation of cAMP. Neither of the other two genes was able to direct the synthesis of a receptor. Nucleotide sequence analysis revealed that these two genes are 98% identical to each other and 95% identical to the D5 sequence. Relative to the D5 sequence, both contain insertions and deletions that result in several in-frame termination codons. Premature termination of translation is the most likely explanation for the failure of these genes to produce receptors in COS-7 and 293 cells even though their messages are transcribed. We conclude that the two are pseudogenes. Blot hybridization experiments performed on rat genomic DNA suggest that there is one D5 gene in this species and that the pseudogenes may be the result of a relatively recent evolutionary event.
ChemInform Abstract: Structure‐Based Design of Non‐Peptide HIV Protease Inhibitors (2001)

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Nanoparticle technology: Addressing the fundamental roadblocks to protein biomarker discovery (2009)

The incorporation of affinity baits into N-isopropylacrylamide-hydrogel-based nanoparticles offers a novel technology that addresses the major analytical challenges of disease biomarker discovery. In solution in complex biologic fluids (e.g. blood or urine), core-shell bait-containing nanoparticles can perform three functions in one step: (a) sieve molecules according to size, (b) sequestrate and concentrate target analytes, and (c) protect analytes from degradation.
Virus-Induced Gene Silencing in Soybean (2012)

Understanding the biology of a system requires the association of gene functions to phenotypes and vice versa. Although a large number of resources and genomic tools are available for studies in the crop plant soybean, investigations related to gene function have been lacking. This is largely due to the fact that rapid functional genomics tools have been unavailable for application in soybean. This constraint was recently alleviated when a novel bean pod mottle virus (BPMV)-based system for virus-induced gene silencing in soybean was developed. This methodology exploits the plant's ability to silence virus-encoded sequences as a defense mechanism. Plants infected with recombinant viruses carrying sequences that are identical/near-identical to the plant's own genes suppress the expression of the target endogenous gene(s). Phenotypes associated with suppression of target sequence enable the assignment of functions to specific genes. The strategy involves inserting short sequences of target soybean genes into the viral genome to generate recombinant vectors. Soybean plants are then inoculated with the recombinant vectors, assessed for BPMV propagation and silencing of the target genes. Plants silenced for specific targets can then be analyzed for various different traits depending upon the known/predicted functions of the target genes. Using this strategy, we have identified genes participating in basal, resistance gene-mediated, and systemic immunity in soybean.
Newest hydrogenation catalysts (1985)

A new generation of hydrogenation catalysts, bimetallic palladium catalysts, is now available. They meet the very stringent requirements of new refining and petrochemical industry that has to face a difficult economic period in which the highest performance becomes standard. Therefore the demand for these new very efficient catalysts and for the associated technologies is rapidly growing.
Structural Characterization of Cleaved, Soluble HIV-1 Envelope Glycoprotein Trimers (2013)

Human immunodeficiency virus type 1 (HIV-1) infection is a significant global public health problem for which development of an effective prophylactic vaccine remains a high scientific priority. Many concepts for a vaccine are focused on induction of appropriate titers of broadly neutralizing antibodies (bNAbs) against the viral envelope (Env) glycoproteins gp120 and gp41, but no immunogen has yet accomplished this goal in animals or humans. One approach to induction of bNAbs is to design soluble, trimeric mimics of the native viral Env trimer. Here, we describe structural studies by negative-stain electron microscopy of several variants of soluble Env trimers based on the KNH1144 subtype A sequence. These Env trimers are fully cleaved between the gp120 and gp41 components and stabilized by specific amino acid substitutions. We also illustrate the structural consequences of deletion of the V1/V2 and V3 variable loops from gp120 and the membrane-proximal external region (MPER) from gp41. All of these variants adopt a trimeric configuration that appropriately mimics native Env spikes, including the CD4 receptor-binding site and the epitope for the VRC PG04 bNAb. These cleaved, soluble trimer designs can be adapted for use with multiple different env genes for both vaccine and structural studies.
Previously Unrecognized Vaccine Candidates Control<i>Trypanosoma cruzi</i>Infection and Immunopathology in Mice (2008)

Trypanosoma cruzi is the etiologic agent of Chagas' disease, a major health problem in Latin America and an emerging infectious disease in the United States. Previously, we screened a T. cruzi sequence database by a computational-bioinformatic approach and identified antigens that exhibited the characteristics of good vaccine candidates. In this study, we tested the vaccine efficacy of three of the putative candidate antigens against T. cruzi infection and disease in a mouse model. C57BL/6 mice vaccinated with T. cruzi G1 (TcG1)-, TcG2-, or TcG4-encoding plasmids and cytokine (interleukin-12 and granulocyte-macrophage colony-stimulating factor) expression plasmids elicited a strong Th1-type antibody response dominated by immunoglobulin G2b (IgG2b)/IgG1 isotypes. The dominant IgG2b/IgG1 antibody response was maintained after a challenge infection and was associated with 50 to 90% control of the acute-phase tissue parasite burden and an almost undetectable level of tissue parasites during the chronic phase, as determined by a sensitive T. cruzi 18S rRNA gene-specific real-time PCR approach. Splenocytes from vaccinated-and-infected mice, compared to unvaccinated-and-infected mice, exhibited decreased (approximately 50% lower) proliferation and gamma interferon (IFN-gamma) production when stimulated in vitro with T. cruzi antigens, thus suggesting that protection from challenge infection was not provided by an active T-cell response. Subsequently, the serum and cardiac levels of IFN-gamma and tumor necrosis factor alpha and infiltration of inflammatory infiltrate in the heart were decreased in vaccinated mice during the course of infection and chronic disease development. Taken together, these results demonstrate the identification of novel vaccine candidates that provided protection from T. cruzi-induced immunopathology in experimental mice.
Hemagglutinin Sequence Conservation Guided Stem Immunogen Design from Influenza A H3 Subtype (2015)

Seasonal epidemics caused by influenza A (H1 and H3 subtypes) and B viruses are a major global health threat. The traditional, trivalent influenza vaccines have limited efficacy because of rapid antigenic evolution of the circulating viruses. This antigenic variability mediates viral escape from the host immune responses, necessitating annual vaccine updates. Influenza vaccines elicit a protective antibody response, primarily targeting the viral surface glycoprotein hemagglutinin (HA). However, the predominant humoral response is against the hypervariable head domain of HA, thereby restricting the breadth of protection. In contrast, the conserved, subdominant stem domain of HA is a potential "universal" vaccine candidate. We designed an HA stem-fragment immunogen from the 1968 pandemic H3N2 strain (A/Hong Kong/1/68) guided by a comprehensive H3 HA sequence conservation analysis. The biophysical properties of the designed immunogen were further improved by C-terminal fusion of a trimerization motif, "isoleucine-zipper", or "foldon". These immunogens elicited cross-reactive, antiviral antibodies and conferred partial protection against a lethal, homologous HK68 virus challenge in vivo. Furthermore, bacterial expression of these immunogens is economical and facilitates rapid scale-up.
AN INVESTIGATION OF METALLURGICAL FACTORS WHICH AFFECT THE FRACTURE TOUGHNESS OF ULTRA HIGH STRENGTH STEELS (1973)

The relationship between microstructure, heat treatment and room temperature fracture toughness has been determined for the low alloy ultra-high strength steels 4130, 4330, 4340, 4140 and 300-M. Optical metallography, microprobe analysis, and scanning electron microscopy were used to characterize the structure and morphology, while both Charpy V-notch impact tests and plane strain fracture toughness tests were used to determine the fracture properties. The normal commercial heat treatment resulted in the formation of some bainite in all the alloys. MnS inclusions on prior austenite grain boundaries were found to initiate cracks during loading. By increasing the austenitizing temperature to l200 C, the fracture toughness could be increased by at least 60%. For some alloys increasing the severity of the quench in conjunction with the higher austenitizing temperatures resulted in further increases in the fracture toughness, and the elimination of any observable upper bainite. There was no correlation between the Charpy impact test results and the fracture toughness results. The alloys 4130, 4140, 4340 all showed a severe intergranular embrittlement when austenitized at high temperatures and tempered above 200 C, while the alloys 4330 and 300-M exhibited no drop in toughness for the same heat treatment conditions. The as-quenched tensile specimens had a very low 'micro' yield strength which rapidly increased to the level of the 'macro' yield strength when tempered.