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91.
Peptide mimics with constrained backbone and side-chain geometry are important tools for studying structure activity relationships of biologically active candidates. A general method for creating β-turn mimics possessing side-chain diversity has been developed featuring diastereoselective S(N)1 displacements of an iodide precursor. In particular, 6-iodo-pyrroloazepin-2-one amino ester 10 has served as a common precursor in reactions with a variety of alcohol, phenol, nitrate, and azide nucleophiles to provide an array of constrained peptide mimics. 相似文献
92.
Low cost and scalable manufacture of lab-on-chip devices for applications such as point-of-care testing is an urgent need. Weaving is presented as a unified, scalable and low-cost platform for the manufacture of fabric chips that can be used to perform such testing. Silk yarns with different properties are first selected, treated with the appropriate reagent solutions, dried and handloom-woven in one step into an integrated fabric chip. This platform has the unique advantage of scaling up production using existing and low cost physical infrastructure. We have demonstrated the ability to create pre-defined flow paths in fabric by using wetting and non-wetting silk yarns and a Jacquard attachment in the loom. Further, we show that yarn parameters such as the yarn twist frequency and weaving coverage area may be conveniently used to tune both the wicking rate and the absorptive capacity of the fabric. Yarns optimized for their final function were used to create an integrated fabric chip containing reagent-coated yarns. Strips of this fabric were then used to perform a proof-of-concept immunoassay with sample flow taking place by capillary action and detection being performed by a visual readout. 相似文献
93.
94.
Let be a pre-defined set of rational numbers. We say that a set of natural numbers is an -quotient-free set if no ratio of two elements in belongs to . We find the maximal asymptotic density and the maximal upper asymptotic density of -quotient-free sets when belongs to a particular class.It is known that in the case , where , are coprime integers greater than 1, the latter problem is reduced to the evaluation of the largest number of non-adjacent lattice points in a triangle whose legs lie on the coordinate axes. We prove that this number is achieved by choosing points of the same color in the checkerboard coloring. 相似文献
95.
A long-wavelength IR broadband reflector is demonstrated using a high-index-contrast subwavelength grating based on a Si/SiO2 system. The field response has been computationally and experimentally verified to exhibit broadband reflectance in the spectral range of 13-16 μm with Δλ/λ=18.5% for reflectance >70%. The gratings exhibit incident field polarization dependence with an average extinction ratio of 1:1.6. 相似文献
96.
Lorena Zapata-Cuellar Jorge Gaona-Bernal Carlos Alberto Manuel-Cabrera Moiss Martínez-Velzquez Carla Snchez-Hernndez Darwin Elizondo-Quiroga Tanya Amanda Camacho-Villegas Abel Gutirrez-Ortega 《Molecules (Basel, Switzerland)》2021,26(15)
Virus-like particles are excellent inducers of the adaptive immune response of humans and are presently being used as scaffolds for the presentation of foreign peptides and antigens derived from infectious microorganisms for subunit vaccine development. The most common approaches for peptide and antigen presentation are translational fusions and chemical coupling, but some alternatives that seek to simplify the coupling process have been reported recently. In this work, an alternative platform for coupling full antigens to virus-like particles is presented. Heterodimerization motifs inserted in both Tobacco etch virus coat protein and green fluorescent protein directed the coupling process by simple mixing, and the obtained complexes were easily taken up by a macrophage cell line. 相似文献
97.
Nozomi Mihara Tanya K. Ronson Jonathan R. Nitschke 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12627-12631
Controlled directional transport of molecules is essential to complex natural systems, from cellular transport up to organismal circulatory systems. In contrast to these natural systems, synthetic systems that enable transport of molecules between several spatial locations on the macroscopic scale, when external stimuli are applied, remain to be explored. Now, the transfer of a supramolecular cage is reported with controlled directionality between three phases, based on a cage that responds reversibly in two distinct ways to different anions. Notably, circulatory phase transfer of the cage was demonstrated based on a system where the three layers of solvent are arranged within a circular track. The direction of circulation between solvent phases depended upon the order of addition of anions. 相似文献
98.
A general model of excitation and fluorescence recapturing by the forward and backward modes of filled microstructured optical fibers (MOFs) is presented. We also present experimental results for both backward and forward fluorescence recapturing within a MOF as a function of fiber length and demonstrate a good qualitative agreement between the numerical model and experimental results. We demonstrate higher efficiency of fluorescence recapturing into backward modes in comparison with that of forward modes. 相似文献
99.
Tanya L. Díaz-Ortiz Mirna Rivera-Claudio Carlos R. Cabrera-Martínez Rolando J. Tremont 《Applied Surface Science》2008,254(6):1587-1592
Gold surfaces have been modified by self-assembled techniques. Here the adsorption time of diasteroisomers (1R, 3S)-1-ferrocenyl-3-methyl-4,4-diphenyl-2,5-dioxacyclopentane and (1S, 3S)-1-ferrocenyl-3-methyl-4,4-diphenyl-2,5-dioxacyclopentane (Scheme 1, 3a and 3b) at a Au surface in ethanol solution was controlled. This study was followed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) analysis. The method used for the surface modification was the control of exposure time of a Au surface in the modifier/ethanol solution. It was demonstrated by EIS and XPS that the Au surface was modified with mixture of compounds 3a + 3b, avoiding the electron transference in the interface. It was also observed that the organometallic molecule indeed had been adsorbed on the Au surface. In addition, evidence seems to conclude that the molecule-Au interaction is through the electrons of cyclopentadienyl moiety, where the oxygen atoms are near the air-molecule interface and the iron atom is near the Au surface. This type of interaction of the ferrocene derivatives with gold surfaces has not been reported by any other author. 相似文献
100.
High spatial resolution surface imaging and analysis of fungal cells using SEM and AFM 总被引:1,自引:1,他引:0
We review the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and force spectroscopy (FS) for probing the ultrastructure, chemistry, physical characteristics and motion of fungal cells. When first developed, SEM was used to image fixed/dehydrated/gold coated specimens, but here we describe more recent SEM developments as they apply to fungal cells. CryoSEM offers high resolution for frozen fungal samples, whereas environmental SEM allows the analysis of robust samples (e.g. spores) under ambient conditions. Dual beam SEM, the most recently developed, adds manipulation capabilities along with element detection. AFM has similar lateral and better depth resolution compared to SEM, and can image live cells including growing fungal hyphae. FS can analyze cell wall chemistry, elasticity and dynamic cell characteristics. The integration of AFM with optical microscopy will allow examination of individual molecules or cellular structures in the context of fungal cell architecture. SEM and AFM are complementary techniques that are clarifying our understanding of fungal biology. 相似文献