A new ferrocenyl uracil peptide nucleic acid (PNA) monomer, tert-butyl-2-(N-(2-(((9H-floren-9-yl)methoxy)carbonylamino)ethyl)-2-(5-(N-ferrocenylmethylbenzamido)-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)acetate (1), has been successfully prepared in good yield by a procedure involving the one-pot reaction of the key synthon, 5-(ferrocenylmethylamino)pyrimidine-2,4(1H,3H)-dione (4), itself prepared from the reaction of (ferrocenylmethyl)trimethylammonium iodide and 5-aminouracil, with benzoyl chloride followed by ethyl bromoacetate. After hydrolysis of the ester, the acid was coupled with a protected PNA backbone to generate 1. NMR spectroscopy showed that 1 hydrogen bonds 9-ethyladenine (EA) in a 1:1 mixture of CD3CN:CDCl3 with an association constant Ka of 70 M(-1) at 30 degrees C. This value is comparable with those observed for model receptors and shows that the ferrocenyl moiety of 1 does not hinder the hydrogen bonding of our new PNA monomer to the complementary DNA base or if it does, not significantly. 1 is oxidized to 1+ with a reversible potential of +538 mV vs the DMFc(0/+) (decamethylferrocene) couple under voltammetric conditions in a 1:1 mixture of CH3CN:CHCl3 (0.1 M Bu4NPF6). For this reversible process, a slightly larger diffusion coefficient of 4.2 x 10(-6) cm(2).s(-1) than usually found for these compounds was determined from these electrochemical studies, which should be analytically useful as it will readily afford submicromolar voltammetric detection limits. 相似文献
OBJECTIVES: The purpose of the present article was to evaluate how shamans and the suburban communities of Quito interpret the terminology used in genetics. METHODS: One hundred people living in 5 suburban districts of Quito were surveyed as well as 19 shamans of the Salasaca community. RESULTS: The results show that members of both groups are little informed about genetics. As knowledge about genetics is correlated to educational level, which is very poor in both groups, knowledge and understanding of genetics are either very basic or nonexistent. As for the medical practices in treating genetic alterations, the surveys show that while in very severe cases scientific medicine is sought, in most cases explanations and a cure are given by shamanic medicine. CONCLUSION: There is limited knowledge of genetics and its terminology in the study population. Shamanic and marginal health practices seem to remain prevalent in these communities due to their low costs, the personal attention the individuals receive, and the holistic point of view employed. It is important that the community councils, the medical doctors and the shamans work together to set up community programs on medical education, particularly on genetics. 相似文献
Inversion over a finite field is usually an expensive operation which is a crucial issue in many applications, such as cryptography and error-control codes. In this paper, three different strategies for computing the inverse over binary finite fields , called Eulerian, Gaussian, and Euclidean, respectively, are discussed and compared in terms of time and space complexity. In particular, some new upper and lower bounds to the respective complexities are evaluated. 相似文献
The combination of imidazolium surfactants with α‐cyclodextrins (CDs, in green) was used as a control element in the thermoregulated aqueous olefin hydroformylation. The self‐assembly of the imidazolium surfactants (red) favors the micellization process at high temperatures, whereas at lower temperatures the complexation of the surfactant monomers into the α‐CDs is favored.
Hydrogen peroxide (H2O2) is an important industrial chemical, but its current production methods are highly energy-intensive. This study presents a novel process for the production of H2O2 based on the bioelectrochemical oxidation of wastewater organics at an anode coupled to the cathodic reduction of oxygen to H2O2. At an applied voltage of 0.5 V, this system was capable of producing 1.9 ± 0.2 kg H2O2/m3/day from acetate at an overall efficiency of 83.1 ± 4.8%. As most of the required energy was derived from the acetate, the system had a low energy requirement of 0.93 kWh/kg H2O2. 相似文献
Ultrahigh-molar-mass (M) polymers such as DNA, cellulose, and polyolefins are routinely analyzed using size-exclusion chromatography (SEC) to obtain
molar mass averages, distributions, and architectural information. It has long been contended that high-M polymers can degrade during SEC analysis; if true, the inaccurate molar mass information obtained can adversely affect decisions
regarding processing and end-use properties of the macromolecules. However, most evidence to the effect of degradation has
been circumstantial and open to alternative interpretation. For example, the shift in SEC elution volume as a function of
increased chromatographic flow rate, observed using only a concentration-sensitive detector, may be the result of degradation
or of elution via a nondegradatory slalom chromatography mechanism. Here, using both concentration-sensitive and multiangle
static light-scattering detection, we provide unambiguous evidence that the polysaccharide alternan actually degrades during
SEC analysis. The decrease in molar mass and size of alternan with increasing flow rate, measured using light scattering,
allows ruling out an SC mode of elution and can only be interpreted as due to degradation. These findings demonstrate the
extreme fragility of ultrahigh-M polymers and the care that must be taken for accurate characterization.
Figure Scission of alternan chains in liquid chromatography. 相似文献
A new crystal form of 2‐methyl‐6‐nitroaniline, C7H8N2O2, crystallizing with Z′ = 2 in the space group P21/c, has been identified during screening for salts and cocrystals. The different N—H...O hydrogen‐bonding synthons result in linear V‐shaped chains in the new polymorph, rather than the helical chain arrangement seen in the known form where Z′ = 1. The presence of a second component during crystallization appears to have determined the resultant crystal form of 2‐methyl‐6‐nitroaniline. 相似文献
Quantification of intracellular nanoscale macromolecular density distribution is a fundamental aspect to understanding cellular processes. We report a near-field penetrating optical microscopy (NPOM) technique to directly probe the internal nanoscale macromolecular density of biological cells through quantification of intracellular refractive index (RI). NPOM inserts a tapered optical fiber probe to successive depths into an illuminated sample. A 50 nm diameter probe tip collects signal that exhibits a linear relationship with the sample RI at a spatial resolution of approximately 50 nm for biologically relevant measurements, one order of magnitude finer than the Abbe diffraction limit. Live and fixed cell data illustrate the mechanical ability of a 50 nm probe to penetrate biological samples. 相似文献
The known 1,3,4-oxathiazol-2-ones with crystal structures reported in the Cambridge Structural Database are limited (13 to date) and this article expands the library to 15. In addition, convenient starting materials for the future exploration of 1,3,4-oxathiazol-2-ones are detailed. An unexpected halogenated propanamide has also been identified as a by-product of one reaction, presumably reacting with HCl generated in situ. The space group of 5-[(E)-2-chloroethenyl]-1,3,4-oxathiazol-2-one, C4H2ClNO2S, ( 1 ), is P21, with a high Z′ value of 6; the space group of rac-2,3-dibromo-3-chloropropanamide, C3H4Br2ClNO, ( 2 ), is P21, with Z′ = 4; and the structure of rac-5-(1,2-dibromo-2-phenylethyl)-1,3,4-oxathiazol-2-one, C10H7Br2NO2S, ( 3 ), crystallizes in the space group Pca21, with Z′ = 1. Both of the structures of compounds 2 and 3 are modeled with two-component disorder and each molecular site hosts both of the enantiomers of the racemic pairs (S,S)/(R,R) and (R,S)/(S,R), respectively. 相似文献