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排序方式: 共有407条查询结果,搜索用时 15 毫秒
91.
Rajagopal Shyamala Joshya Hélène Carrère Victor Guadalupe Ibarra-Sierra Juan Carlos Sandoval-Santana Vladimir K. Kalevich Eugeniyus L. Ivchenko Xavier Marie Thierry Amand Alejandro Kunold Andrea Balocchi 《Advanced functional materials》2021,31(27):2102003
The detection of light helicity is key for various applications, from drug production to optical communications. However, the light helicity direct measurement is inherently impossible with conventional photodetectors based on III–V or IV–VI non-chiral semiconductors. The prior polarization analysis by often moving optical elements is necessary before light is sent to the detector. A method is here presented to effectively give the conventional dilute nitride GaAs-based semiconductor epilayer a chiral photoconductivity. The detection scheme relies on the giant spin-dependent recombination of conduction electrons and the accompanying spin polarization of the engineered defects to control the conduction band. As the conduction electron spin polarization is, in turn, intimately linked to the excitation light polarization, the light polarization state and intensity can be determined by a simple conductivity measurement. This approach, removing the need for any optical elements in front of a non-chiral detector, could offer easier integration and miniaturization. This new chiral photodetector could potentially operate in a spectral range from the visible to the infra-red using (InGaAl)AsN alloys or ion-implanted nitrogen-free III–V compounds. 相似文献
92.
David Corral-Plaza Juan Boubeta-Puig Guadalupe Ortiz Alfonso Garcia-de-Prado 《计算机系统科学与工程》2020,35(1):5-12
Air pollution is currently receiving more attention by international governments and organizations. Nevertheless, current systems for air quality monitoring
lack essential requirements which are key in order to be effective concerning users’ access to the information and efficient regarding real-time monitoring
and notification. This paper presents an Internet of Things platform for air station remote sensing and smart monitoring that combines Big Data and Cloud
Computing paradigms to process and correlate air pollutant concentrations coming from multiple remote stations, as well as to trigger automatic and
personalized alerts when a health risk for their particular context is detected. This platform has been tested by analyzing the results of observing Andalusian,
South of Spain, sensor network during a long period of time. The results show that this novel solution can help to reduce the impact of air pollution on
human health since citizens are alerted in real time. 相似文献
93.
Sulfuric acid treatment of ground tire rubber and its effect on the mechanical and thermal properties of polypropylene composites
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Ernesto Hernández Hernández José Francisco Hernández Gámez Lorena Farías Cepeda Esthela Judith Chávez Muñoz Florentino Soriano Corral Silvia Guadalupe Solís Rosales Guadalupe Neira Velázquez Pablo González Morones Deidré I. Sánchez Martínez 《应用聚合物科学杂志》2017,134(21)
Ground tire rubber (GTR) was modified by sulfuric acid in order to improve its compatibility with and reinforcement of a polypropylene (PP) matrix. Polymer composites PP/GTR were prepared by melt mixing at different concentrations, with a maximum of 50 wt % of GTR. Studies by Fourier transform infrared spectroscopy (FTIR), surface specific area by BET (Brunauer, Emmett, and Teller), and scanning electron microscopy were used to characterize the untreated GTR and treated GTR, while the mechanical and thermal properties of the PP/GTR composites were assessed to understand how the surface treatment of GTR affected the mechanical and thermal properties of the composite PP/GTR. FTIR revealed the presence of sulfonic groups on the surface of sulfuric acid–treated GTR, and BET analyses showed an increase of about 625% in the specific surface area as a result of the high porosity produced by the treatment. In all composites containing treated GTR, a higher Young's modulus was obtained than for composites containing untreated GTR. Particularly, an increase of about 275% in the Young's modulus was obtained in composites with treated GTR (40 wt %) against that containing untreated GTR. However, a more significant reduction of the elongation at break was observed in composites containing treated GTR than in those containing untreated GTR. Also, an increase of the crystallization temperature of PP as a function of GTR was observed by differential scanning calorimetry, but the crystallinity of the composites was reduced by the addition of both untreated and treated GTR. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44858. 相似文献
94.
González-Quijada MR Alanís-Guzman MG Serna-Saldivar SO 《Archivos latinoamericanos de nutrición》2003,53(1):84-89
Different combinations of pHs (2 to 12) and temperatures (25, 30 and 35 degrees C) were tested to obtain a protein isolate from ebony (Pithecellobium flexicaule, Benth) seeds. Seed proteins contained 54.6% albumins, 32% globulins, 5.7% glutelins and 1.3% prolamins. The isoelectric points for albumins, globulins and glutelins were in the pH range of 2.3-2.7. The average molecular weight of albumins ranged from 92 to 100 kDa and for the four globulin subunits in the range of 28.4 to 57.3 kDa. For isolate production, proteins were sequentially extracted with distilled water and a 5% NaCl solution. The resulting supernatants were mixed. The best extraction was achieved at pH 11 and 25 degrees C. 45.6% of the total seed protein was precipitated at pH 2.6 yielding an isolate with 90% protein (N x 6.25). The isolate contained high quantities of lysine, leucine, threonine and phenylalanine but were low in sulfur containing amino acids methionine and cysteine. The extraction process reduced tannins, phytates and trypsin inhibitor in 53, 70 and 70%, respectively. In vivo protein digestibility of the protein isolate was 85.4% and the corrected digestibility essential amino acid score was of 44% due to the lack of sulfur containing amino acids. In order to upgrade the protein quality of ebony isolate it is recommend to supplement with methionine or sulfur containing rich foods. 相似文献
95.
96.
Mammalian cell expression of dimeric small immune proteins (SIP) 总被引:4,自引:0,他引:4
Li E; Pedraza A; Bestagno M; Mancardi S; Sanchez R; Burrone O 《Protein engineering, design & selection : PEDS》1997,10(6):731-736
We have designed and expressed bivalent small immune proteins (SIP) based
on scFv fragments connected through a short linker of four amino acids to
the CH3 domain of the human immunoglobulin gamma 1 H-chain. Three different
versions have been designed and expressed in mammalian cells. In one
construct a cysteine residue was included in the last amino acid of the
flexible 15-amino acid long linker connecting the V(L) and V(H) domains,
thus creating a disulphide bond stabilized molecule. A version with a
shorter (five amino acids) V(L)/V(H) linker was also produced and shown to
be efficiently assembled and secreted. All three SIPs form dimers retaining
their antigenic specificity in Western blotting and having a comparable
functional affinity (avidity) as determined by ELISA.
相似文献
97.
Guadalupe Del C. Pizarro Oscar G. Marambio Manuel Jeria‐Orell Margarita R. Huerta Oscar O. Rodríguez Bernabé L. Rivas Kurt E. Geckeler 《应用聚合物科学杂志》2007,105(5):2893-2902
This article reports the synthesis of poly(N‐maleoylglycine‐co‐itaconic acid) by radical copolymerization under different feed mole ratios and its properties to remove various metal ions, such as Cu(II), Cr(III), Co(II), Zn(II), Ni(II), Pb(II), Cd(II), and Fe(III), in aqueous phase with the liquid‐phase polymer‐based retention(LPR) technique. The interactions of inorganic ions with the hydrophilic water‐soluble polymer were determined as a function of pH and filtration factor. Metal ion retention was found to strongly depend on the pH. Metal ion retention increased as pH and MG content units in the macromolecular backbone increased. The copolymers were characterized by elemental analysis, FTIR, 1H‐NMR, and 13C‐NMR spectroscopy. Additionally, intrinsic viscosity, molecular weight, and polydispersity have been determined for the copolymers. Copolymer and polymer–metal complex thermal behavior was studied using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques under nitrogen atmosphere. The thermal decomposition temperatures (TDT) were influenced by the copolymer composition. The copolymers present lower TDT than the polymer–metal complex with the same copolymer composition. All copolymers present a single Tg, indicating the formation of random copolymers. A slight deviation of the Tg for the copolymers and its complexes can be observed. The copolymer Tg is higher than the Tg value for the polymer–metal complexes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
98.
Juan Morales‐Corona José A. López‐Barrera Alejandro Avila‐Ortega Guillermo J. Cruz María‐Guadalupe Olayo Mauricio Ortega‐López Miguelina Vasquez‐Ortega Humberto Vazquez Roberto Olayo 《应用聚合物科学杂志》2012,123(2):1120-1124
This work presents the synthesis by plasma and characterization of luminescent polymer thin films of dibenzothiophene (DBT) by plasma polymerization. The DBT is solid at room conditions and was sublimated and introduced to the plasma reactor to produce the chemical reactions with the vapors. The results indicated the production of polymers with benzene and thiophene rings in the structure as well as methylene groups. The polymer structure was studied by Fourier transform infrared spectroscopy and 13C‐CPMAS. The thermal analysis showed a residual mass of 60% at 800°C, which suggests a great thermal resilience in the polymer. The critical superficial tension was calculated with a Zisman plot and was 25 mN/m. The polymer has a fluorescent green emission between 400 and 660 nm and an orange emission between 660 and 850 nm. This effect can be a consequence of the electronic distribution along the structure in aliphatic and aromatic segments with benzene and thiophene rings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
99.
Carlos Eduardo Molina-Guerrero Guadalupe de la Rosa Hiram Castillo-Michel Arturo Sánchez Concepción García-Castañeda Angélica Hernández-Rayas Idania Valdez-Vazquez Santiago Suarez-Vázquez 《化学工程与技术》2018,41(7):1350-1350
The changes occurring during the depolymerization of lignocellulosic biomasses are not yet fully understood. Synchrotron micro‐Fourier transform infrared (µ‐FTIR), Raman spectroscopy (RS), X‐ray diffraction (XRD), and X‐ray fluorescence (XRF) were applied for better characterization of wheat straw fibers during a continuous pretreatment process in terms of conditioning (C), extrusion (E), steam explosion (SE), and enzymatic hydrolysis (EH). µ‐FTIR revealed functional groups as phenylpropanoid polymers, ethers, and aliphatic alcohol. RS detected acetoacetate, methyl and phenol groups after SE. The crystallinity index and silica content were also determined. 相似文献
100.
Vermont P. Dia Sarah Frankland-Searby Francisco Laso del Hierro Guadalupe Garcia Elvira Gonzalez de Mejia 《Food chemistry》2013
Lunasin is a 43-amino acid naturally occurring chemopreventive peptide with demonstrated anti-cancer and anti-inflammatory properties. The objectives of this study were to determine the effect of temperature on the secondary structure of lunasin, to develop a method of isolating lunasin from human plasma using an ion-exchange microspin column and to quantify the amount of lunasin using an optimized enzyme-linked immunosorbent assay. Lunasin was purified using a combination of ion-exchange chromatography, ultrafiltration and gel filtration chromatography. Circular dichroism showed that increased in temperature from 25 to 100 °C resulted in changes on the secondary structure of lunasin and its capability to interact with rabbit polyclonal antibody. Enzyme linked immunosorbent assay showed that lunasin rabbit polyclonal antibody has a titer of 250 and a specific activity of 0.05 mL/μg. A linear response was detected between 16 to 48 ng lunasin per mL (y = 0.03x − 0.38, R2 = 0.96). The use of diethylaminoethyl microspin column to isolate spiked lunasin in human plasma showed that most lunasin (37.8–46.5%) bound to the column eluted with Tris–HCl buffer, pH 7.5 with a yield up to 76.6%. In conclusion, lunasin can be isolated from human plasma by a simple DEAE microspin column technique and can be quantified using a validated and optimized immunoassay procedure. This method can be used directly to quantify lunasin from plasma in different human and animal studies aiming to determine its bioavailability. 相似文献