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1.
Amy Fisher 《Ambix》2018,65(2):169-189
As a professor of chemistry at the University of Pennsylvania, Robert Hare actively shaped early American science. He participated in a large network of scholars, including Joseph Henry, François Arago, and Jacob Berzelius, and experimented with and wrote extensively about electricity and its associated chemical and thermal phenomena. In the early nineteenth century, prominent chemists such as Berzelius and Humphry Davy proclaimed that a revolution had occurred in chemistry through electrical research. Examining Robert Hare’s contributions to this discourse, this paper analyzes how Hare’s study of electricity and the caloric theory of heat led him to propose a new theory of galvanism. It also examines the reception of Hare’s work in America and Great Britain, highlighting the contributions of early American chemists to the development of electrochemistry.  相似文献   

2.
《Ambix》2013,60(2):159-173
Abstract

This paper is about the life and scientific achievements of François Joseph Houtou de Labillardière, a French chemist from the first half of the nineteenth century who is quite unknown, but who made some significant contributions to chemical research in the first quarter of the nineteenth century. His retirement from chemical research at the age of 37 years had two main causes: his personal enrichment, owing to family inheritances and to profitable contributions to the chemistry of dyes; and his personal disputes with different, well-known colleagues of the time, such as Payen and Gay-Lussac.  相似文献   

3.
《Ambix》2013,60(2):145-150
Abstract

This paper uses case studies of the cities of Nancy and Metz to demonstrate that chemistry was established as a thriving public science in the French provinces in the last decades of the old regime. It shows that physicians and apothecaries were key figures in this development. I argue that a detailed study of how such minor figures as Henry Michel du Tennetar and Pierre François Nicolas in Nancy constructed their public lives and careers can help us to a broader analysis, one that is not exclusively metropolitan, of the social, cultural, economic and political forces that shaped chemistry in France in the period of the Chemical and French Revolutions.  相似文献   

4.
5.
Pasteur’s major discovery in chemistry was the recognition of molecular chirality, in 1848. He understood that his new science needed its own language, and introduced new terminology and nomenclature, thereby launching modern stereochemical language. He was eminently prepared for this task as a refined user of language, skills recognized by his election to the Académie française, the supreme institution for the protection and promotion of the French language. The terms chiral and chirality did not exist at the time and he adopted the French word dissymmétrie (dissymmetry) for the phenomenon of handedness. Although in his time almost nothing was known about molecular constitution and configuration, his insights allowed him to create useful language some of which is still used today in stereochemistry, e. g., racemic for the 1 : 1 mixture of the two enantiomers, and the use of the prefixes levo‐ and dextro‐ in the names of optically active substances. On the other hand, the limitations in the knowledge of organic chemistry at the time prevented him from creating some needed terms, e. g., for the phenomenon of diastereoisomerism. He also failed to adopt the enantio terminology introduced in the 1850s by German mineralogist Carl Friedrich Naumann. Analysis of Pasteur’s linguistic innovations is of interest from the point of view of the history of chemistry and is also useful in throwing light on the fundamental nature of the concepts of stereochemistry. Such understanding has acquired a new relevance due to the considerable misuse and misunderstanding of this language seen in the literature today.  相似文献   

6.
Experimental refractive indices and molar refractions for the binary mixtures of each of the isomers of chlorobutane with each of the isomers of butanol are given at 298.15?K. From these data the refractive index deviations were calculated. The experimental refractive index results were compared with those predicted by several mixing rules: Lorentz–Lorenz, Gladstone–Dale, Arago–Biot, Wiener and Heller.  相似文献   

7.
An innovative approach is presented to interpret the refractive index of binary liquid mixtures. The concept of refractive index “before mixing” is introduced and shown to be given by the volume‐fraction mixing rule of the pure‐component refractive indices (Arago–Biot formula). The refractive index of thermodynamically ideal liquid mixtures is demonstrated to be given by the volume‐fraction mixing rule of the pure‐component squared refractive indices (Newton formula). This theoretical formulation entails a positive change of refractive index upon ideal mixing, which is interpreted in terms of dissimilar London dispersion forces centred in the dissimilar molecules making up the mixture. For real liquid mixtures, the refractive index of mixing and the excess refractive index are introduced in a thermodynamic manner. Examples of mixtures are cited for which excess refractive indices and excess molar volumes show all of the four possible sign combinations, a fact that jeopardises the finding of a general equation linking these two excess properties. Refractive indices of 69 mixtures of water with the amphiphile (R,S)‐1‐propoxypropan‐2‐ol are reported at five temperatures in the range 283–303 K. The ideal and real refractive properties of this binary system are discussed. Pear‐shaped plots of excess refractive indices against excess molar volumes show that extreme positive values of excess refractive index occur at a substantially lower mole fraction of the amphiphile than extreme negative values of excess molar volume. Analysis of these plots provides insights into the mixing schemes that occur in different composition segments. A nearly linear variation is found when Balankina’s ratios between excess and ideal values of refractive indices are plotted against ratios between excess and ideal values of molar volumes. It is concluded that, when coupled with volumetric properties, the new thermodynamic functions defined for the analysis of refractive indices of liquid mixtures give important complementary information on the mixing process over the whole composition range.  相似文献   

8.
Density, refractive index, and dynamic viscosity of two new ionic liquids involving the 1-benzyl-3-methyl imidazolium cation and the common anions chloride and methylsulfate have been determined and correlated as a function of temperature. Volumetric properties for the ionic liquids are calculated from the density and the results are also enclosed. The Lorentz–Lorenz, Dale–Gladstone, Eykman, Oster, Arago–Biot, and Newton equations, as well as a modified Eykman were used to correlate satisfactorily the relation between the densities and refractive indices of the selected ionic liquids. The influence of the benzyl group on the density was compared with other alkyl imidazolium cations and the same anions.  相似文献   

9.
In honor of the 97th birthday of Professor John D. Roberts, the author has assembled a collection of poignant quotes and anecdotes, mostly written by Roberts himself, which embody his philosophies of life and his wide‐ranging experiences and interests. A brief summary of Roberts’s major scientific accomplishments is also presented.  相似文献   

10.
Cooling and trapping of neutral atoms using laser techniques has enabled extensive progress in precise, coherent spectroscopy. In particular, trapping ultracold atoms in optical lattices in a tight confinement regime allows us to perform high‐resolution spectroscopy unaffected by atomic motion. We report on the recent developments of optical lattice atomic clocks that have led to optical spectroscopy coherent at the one second timescale. The lattice clock techniques also open a promising pathway toward trapped ultracold molecules and the possible precision measurement opportunities such molecules offer.  相似文献   

11.
Dual responsive inverse opal hydrogels were designed as autonomous sensor systems for (bio)macromolecules, exploiting the analyte‐induced modulation of the opal’s structural color. The systems that are based on oligo(ethylene glycol) macromonomers additionally incorporate comonomers with various recognition units. They combine a coil‐to‐globule collapse transition of the LCST type with sensitivity of the transition temperature toward molecular recognition processes. This enables the specific detection of macromolecular analytes, such as glycopolymers and proteins, by simple optical methods. While the inverse opal structure assists the effective diffusion even of large analytes into the photonic crystal, the stimulus responsiveness gives rise to strong shifts of the optical Bragg peak of more than 100 nm upon analyte binding at a given temperature. The systems’ design provides a versatile platform for the development of easy‐to‐use, fast, and low‐cost sensors for pathogens.  相似文献   

12.
The initial steps toward optical detection and spectroscopy of single molecules in condensed matter arose out of the study of inhomogeneously broadened optical absorption profiles of molecular impurities in solids at low temperatures. Spectral signatures relating to the fluctuations of the number of molecules in resonance led to the attainment of the single‐molecule limit in 1989 using frequency‐modulation laser spectroscopy. In the early 90s, many fascinating physical effects were observed for individual molecules, and the imaging of single molecules as well as observations of spectral diffusion, optical switching and the ability to select different single molecules in the same focal volume simply by tuning the pumping laser frequency provided important forerunners of the later super‐resolution microscopy with single molecules. In the room temperature regime, imaging of single copies of the green fluorescent protein also uncovered surprises, especially the blinking and photoinduced recovery of emitters, which stimulated further development of photoswitchable fluorescent protein labels. Because each single fluorophore acts a light source roughly 1 nm in size, microscopic observation and localization of individual fluorophores is a key ingredient to imaging beyond the optical diffraction limit. Combining this with active control of the number of emitting molecules in the pumped volume led to the super‐resolution imaging of Eric Betzig and others, a new frontier for optical microscopy beyond the diffraction limit. The background leading up to these observations is described and current developments are summarized.  相似文献   

13.
The developments in quantum mechanical calculations of vibrational circular dichroism, vibrational Raman optical activity, and vibrational contributions to optical rotation are summarized. Further developments needed in each of these areas are pointed out. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006  相似文献   

14.
The lithiation of Ntert‐butoxycarbonyl (N‐Boc)‐1,2,3,4‐tetrahydroisoquinoline was optimized by in situ IR (ReactIR) spectroscopy. Optimum conditions were found by using n‐butyllithium in THF at ?50 °C for less than 5 min. The intermediate organolithium was quenched with electrophiles to give 1‐substituted 1,2,3,4‐tetrahydroisoquinolines. Monitoring the lithiation by IR or NMR spectroscopy showed that one rotamer reacts quickly and the barrier to rotation of the Boc group was determined by variable‐temperature NMR spectroscopy and found to be about 60.8 kJ mol?1, equating to a half‐life for rotation of approximately 30 s at ?50 °C. The use of (?)‐sparteine as a ligand led to low levels of enantioselectivity after electrophilic quenching and the “poor man’s Hoffmann test” indicated that the organolithium was configurationally unstable. The chemistry was applied to N‐Boc‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline and led to the efficient synthesis of the racemic alkaloids salsolidine, carnegine, norlaudanosine and laudanosine.  相似文献   

15.
《Tetrahedron: Asymmetry》2006,17(19):2723-2725
Quartz, the most abundant mineral in Earth’s crust, is a chiral crystal. It was the first material for which the phenomenon of the optical rotation was observed. In the late 19th century/beginning of the 20th, several researchers, the most famous of which is Le Châtelier, investigated how this optical rotation changes with temperature. By employing a modern analytical/computational tool for evaluating the degree of chirality on a continuous scale, we were able to show a remarkable agreement between the original optical rotation/temperature curve, and the chirality/temperature curve. We thus provide a direct interpretation of the early observations, as reflected in the dependence of the optical rotation of the degree of chirality, linking these two properties quantitatively.  相似文献   

16.
Beginning early in the 19th century, developments in crystallography, optics, and chemistry in France set the stage for the discovery of molecular chirality by Louis Pasteur in 1848. He found that the crystallization of the sodium ammonium salt of ‘paratartaric acid’, a mysterious ‘isomer’ of natural (+)‐tartaric acid (TA), produced two different crystal types that were non‐superimposable mirror‐image forms of each other. He separated the two types and found their optical rotations in solution opposite in direction and equal in absolute magnitude. This led him to conclude that paratartaric acid is a combination of two mirror‐image molecule types of TA that are ‘dissymmetric’, an existing term he adapted to the connotation of today's ‘chiral’. In 1857, he found that the two enantiomers of TA were metabolized by a microorganism at drastically different rates, and thereby discovered biological enantioselectivity. In 1886, Italian chemist Arnaldo Piutti discovered D ‐asparagine and found that it tasted intensely sweet, in contrast to the known L ‐asparagine which had no taste. This was the discovery of stereoselectivity at biological receptors. As a result of advances in stereoselective synthesis and enantioselective chromatography during the last decades of the 20th century, in the 1990s the importance of molecular chirality in drug action and disposition began to receive serious attention from drug‐regulatory authorities and the pharmaceutical industry, the overall result of which has been the near‐complete disappearance of racemic drugs as newly introduced pharmaceuticals.  相似文献   

17.
Remarkable magneto‐optical properties of a new isolator material, that is, europium sulfide nanocrystals with gold (EuS–Au nanosystem), has been demonstrated for a future photo‐information technology. Attachment of gold particles that exhibit surface plasmon resonance leads to amplification of the magneto‐optical properties of the EuS nanocrystals. To construct the EuS–Au nanosystems, cubic EuS and spherical Au nanocrystals have been joined by a variety of organic linkers, that is, 1,2‐ethanedithiol (EDT), 1,6‐hexanedithiol (HDT), 1,10‐decanedithiol (DDT), 1,4‐bisethanethionaphthalene (NpEDT), or 1,4‐bisdecanethionaphthalene (NpDDT) . Formation of these systems was observed by XRD, TEM, and absorption spectra measurements. The magneto‐optical properties of the EuS–Au nanosystem have been characterized by using Faraday rotation spectroscopy. The Faraday rotation angle of the EuS–Au nanosystem is dependent on the Au particle size and interparticle distance between EuS and Au nanocrystals. Enhancement of the Faraday rotation of EuS–Au nanosystems was observed. The spin configuration in the excited state of the EuS–Au nanosystem was also investigated using photo‐assisted electron paramagnetic resonance.  相似文献   

18.
none 《Ambix》2013,60(3):218-240
Abstract

The Brazilian-born man of science Martim Francisco de Andrada (1775–1844) actively participated in some of the major publishing activities of the Portuguese Enlightenment, notably in the Arco do Cego printing house. For many Brazilians, technical and scientific activities provided a path to becoming part of the administrative system of the Portuguese Empire. This paper examines Andrada’s work as translator of Torbern Bergman’s book Sciagraphia Regni Mineralis, secundum principia proxima digesti, originally published in Latin in 1782 and soon translated into French. A comparison between the Portuguese and French editions allows us to understand the different ways in which translators intervened in texts. Martim Francisco established a dialogue both with Bergman and with his translators, Jean-André Mongez and Jean-Claude Delamétherie, in addition to the challenge of having to deal with the propositions set forward by the new pneumatic chemistry. We argue that the Brazilian translator’s main objective was to explore the possibilities of using the book as a teaching and fieldwork manual. From this perspective, the resulting translation gains significance when read at the confluence of these demands and intentions.  相似文献   

19.
Correlations between density and refractive index of pure systems of ionic liquids were examined in this work. To this end, the density and refractive index of four 1-n-butyl-3-imidazolium-based ionic liquids were measured at atmospheric pressure and temperature up to 353.2 K. Densities and refractive indices of the ionic liquids investigated are presented as a function of temperature. A group contribution-based equation was modified to calculate the density as a function of temperature. An empirical equation was used to study the temperature-dependence of refractive index. The Lorentz–Lorenz, Dale–Gladstone, Eykman, Oster, Arago–Biot, and Newton equations, as well as a modified Eykman were used to correlate the relation between the densities and refractive indices of the different ionic liquid systems. The correlations give satisfactory results. The results of this study can add to the newly organized database for ionic liquids and can also be used for various process design calculations.  相似文献   

20.
There is a common phenomenon that the heterogeneity of natural oligosaccharides contains various sugar units, which can be used to enhance affinity and selectivity toward a specific receptor, so the synthesis of heterogeneous glycopolymers is always an important issue in the glycopolymer field. Herein, this study conducts a one‐pot method to prepare polyrotaxane‐based heteroglycopolymers anchored with different sugar units and fluorescent moieties via the combination of host–guest interaction, thiol‐ene, and copper‐catalyzed click chemistry in water. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, X‐ray diffraction, and Ellman's assay test are used in the paper to characterize the compounds. Quartz crystal microbalance‐dissipation (QCD‐D) experiments and bacterial adhesion assay are utilized to study the interactions of polyrotaxane‐based heteroglycopolymers with Con A and Escherichia coli . The results reveal that polyrotaxanes (PRs) with mannose and glucose present better specificity toward Con A and E. coli than PRs with glucose due to synergistic effects.  相似文献   

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