scholarly journals Changes in the Raman spectrum of sulphuric acid on dilution

1934 ◽  
Vol 144 (851) ◽  
pp. 129-143 ◽  
Keyword(s):  
Sulphuric Acid ◽  
Raman Effect ◽  
Wave Length ◽  
Frequency Shifts ◽  
Low Concentrations ◽  
Intensity Changes ◽  
Continuous Background ◽  
Length Determination ◽  
Detailed Interpretation ◽  
Two Stages

The results of previous workers upon the Raman effect of sulphuric acid show a considerable lack of agreement, due no doubt in part to the intensity of the accompanying continuous background and the apparent diffuseness of certain of the lines. Thus both Nisi and Woodward found that change of the concentration of the add greatly modified the appearance of the spectrum, influencing both the positions and the relative intensities of the lines. Wood-ward gave photometer carves of the spectra for concentrations ranging from 100% to 25% by volume, and attributed the observed intensity changes to tho successive stages of ionization of the acid. The lines Δ v = 910 and 1140 cm. -1 (approximate values), which were strong in the 100% acid, became weaker and shifted somewhat as the concentration decreased; while a new line Δ v = 1046 cm. -1 made its appearance and increased correspondingly in intensity. At low concentrations this last line became double, a companion appearing at 982 cm. -1 . The frequencies 910 and 1110 were regarded as characteristic of the H 2 SO 4 molecule, 1016 of the HSO' 4 ion, and 982 of the SO" 4 ion. Other diffuse lines also showed frequency shifts. Bell and Fredrickson. however, whose measurements were made not only with a prism spectrograph but also with a grating, failed to find any appreciable shifts of the line with dilution. Moreover, they stated that on their plates the 1016 line gave no indication of becoming double at low concentrations, but merely grew more diffuse. The findings of other workers are referred to in the discussion of our results (see below). In view of the conflicting nature of the above evidence regarding the two stages of ionisation of the acid, it was thought, desirable to repeat tho investigations using a higher dispersion than that employed by Woodward ( loc. cit .), the object of the work being to obtain more conclusive photometer curves of the spectra. The curves we have actually obtained not only give a clear picture of the intensity changes involved, but have also been used in a rational method of wave-length determination, the adoption of which has made it possible for us to propose a somewhat more detailed interpretation of the spectra than has hitherto been attempted.

scholarly journals Expert-analytical Support of Foreign Policy Activities

2021 ◽  
Vol 14 (5) ◽  
pp. 22-48
Author(s):  
A. A. Varfolomeev ◽  
O. P. Ivanov ◽  
I. V. Surma ◽  
Y. A. Trefilova
Keyword(s):  
Artificial Intelligence ◽  
Foreign Policy ◽  
Foreign Affairs ◽  
Decision Making Process ◽  
Policy Decisions ◽  
The Russian Federation ◽  
Detailed Interpretation ◽  
Two Stages ◽  
Expert Community

The article presents the final results of the project studying the system of expert and analytical support for foreign policy decisions. The project is devoted to conducting a survey and a set of interviews with employees of government bodies (leaders and chief specialists) who are involved in the process of preparing and making foreign policy decisions. The article contains the officials’ assessment of the main challenges when interacting with the scientific and expert community, as well as a "desired image" of such interaction.The study was held in two stages (stage I in February-October 2020, stage II-in January-August 2021) in the form of a survey with a set of follow-up interviews for a more detailed interpretation of the data obtained. The interviewees included 24 employees of federal executive bodies (the Ministry of Foreign Affairs of Russia and Rossotrudnichestvo; departments of international cooperation of line ministries, agencies and services); offices of the chambers of the Federal Assembly of the Russian Federation (departments providing international and inter-parliamentary cooperation). All participants of the study are in positions of the "managers" category or are part of the group of "chief specialists", that is, they have experience in decision-making process and/or in elaborating them. The survey and interviews were anonymous. The research is within structural-functional, institutional and regulatory approaches. The authors note that informational materials with low level of generalization and lacking recommendations and forecasts will never replace genuine analytics and expertise. Given the development of artificial intelligence, generalizing information will be automatized. As a result, expertise has to be of better quality.

THE REACTIONS OF THE HOUSEFLY, MUSCA DOMESTICA LINN., TO LIGHT OF DIFFERENT WAVE-LENGTHS

1938 ◽  
Vol 16d (11) ◽  
pp. 307-342 ◽  
Author(s):  
J. W. MacBain Cameron
Keyword(s):  
White Light ◽  
Copper Sulphate ◽  
Wave Length ◽  
Short Wave ◽  
Quantitative Relation ◽  
Copper Sulphate Solution ◽  
Quartz Mercury ◽  
Intensity Changes ◽  
Constant Quality ◽  
Colored Lights

Houseflies were reared on an artificial medium and tested with different wave-lengths of spectral light obtained from a quartz-mercury arc. The spectrum tested extended from λ3022 Å to λ5780 Å, and the lines were made of approximately equal intensity throughout. In addition, λ5461 Å and λ4078 Å were tested at several other intensities. The comparison standard in all cases was white light, obtained from a tungsten-filament, inside-frosted bulb, and filtered through copper sulphate solution. It was of constant quality, and the intensity was varied by changing the size of the bulb and by varying the distance from the bulb to the copper sulphate filter. The lighted areas to which the flies reacted were 5 by 10 mm. On one of these fell a total intensity of colored light of approximately 10.3 microwatts, on the other a range of intensity of white light of from 0.34 to 36.1 μw.Flies to be tested were removed from the breeding cage ten hours before tests began and were kept in darkness until used. Each fly whose record was used in compiling the final results was caused to make ten trips towards the two test lights, and a record was kept of the choice on each trip.A description and discussion of the four different methods found in the literature for conducting experiments of this type, and for analyzing the results, are included. In the first method, the intensity of the test light of a given wave-length is kept constant, while that of the standard light, usually white, is varied until both are equally attractive.The second method involves testing the colored light against a fixed intensity of white and finding the ratio of insects attracted to color. The intensity of white that will give the same ratio of attractiveness when tested against the standard is then determined.In the third method, the two test lights are made equal in intensity, and their relative efficiency is considered to be directly proportional to the number of insects attracted to each.In the last method, the standard is kept fixed in both quality and intensity, and the intensity of the test color is varied until the two are equal in attractiveness.Application of the first three methods to the same data shows that they give results that vary greatly as the intensity changes. Some show that efficiency increases as the intensity increases, while others show a decrease in efficiency with increasing intensity.If the intensities of all colored lights are equal, the three methods give practically the same qualitative results when applied to the same data. That is, a curve of efficiency is found which has its peak at the same wave-length, whatever method is used. Quantitatively, the results given by the three methods differ, so that no definite ratio of attractiveness can be determined between colors.The data obtained were not amenable to analysis by the fourth method, but published results indicate that this is perhaps the best method for determining the quantitative relation between the stimulative efficiencies of light of different colors.The housefly, M. domestica, is much more strongly stimulated by ultraviolet light of wave-length 3656 Å than by any other part of the spectrum examined. The effect decreases, at first rapidly and then more slowly, as the longer wave-lengths are reached; it also decreases on the short-wave side of the peak. The spectrum available extended only as far as λ3022 Å in the ultraviolet, at which point there was still an appreciable attractiveness, apparently greater than that of either yellow or green.Several problems are suggested that require further investigation.

Dynamic Fourier Transform Polarized Raman Spectroscopy of Polyethylene Fibers under a Modulated Strain

2002 ◽  
Vol 56 (7) ◽  
pp. 809-812 ◽  
Author(s):  
P. R. Griffiths ◽  
D. B. Chase ◽  
R. M. Ikeda ◽  
J. W. Catron
Keyword(s):  
Raman Spectroscopy ◽  
Tensile Deformation ◽  
Infrared Transmission ◽  
Polymeric Fibers ◽  
Frequency Shifts ◽  
Infrared Measurements ◽  
Intensity Changes ◽  
Ft Raman Spectroscopy ◽  
Polarized Raman ◽  
Polyethylene Fibers

The response of materials under stress is a critical aspect of the in-use performance of fibers and films. Dynamic infrared measurements have been shown to be very informative and have provided information about both chain reorientation and conformational state change during deformation. However, the use of infrared transmission techniques necessarily confines the measurements to thin films. Polymeric fibers present a real challenge to this approach. Raman scattering is extremely well suited for fibers. There is no real constraint on sample size, shape, or thickness. Dynamic measurements on fibers under deformation have been extended using a Raman probe. Step-scan FT-Raman spectroscopy has allowed the decoupling of the sample strain frequencies from the Fourier frequencies, and the sensitivity is sufficient to observe the small changes associated with an elastic tensile deformation. For polyethylene fibers, the dynamic spectra exhibit both stress-induced frequency shifts and intensity changes due to chain reorientation. Vibrational modes that are coupled to chain backbone motions are found to exhibit the strongest stress-induced frequency shifts, while decoupled motions, such as C–H stretching modes, exhibit the effects of chain reorientation.

scholarly journals Comparison of the activity and conformation changes of lactate dehydrogenase H4 during denaturation by guanidinium chloride

1991 ◽  
Vol 277 (1) ◽  
pp. 207-211 ◽  
Author(s):  
Y Z Ma ◽  
C L Tsou
Keyword(s):  
Lactate Dehydrogenase ◽  
Active Site ◽  
Cross Linking ◽  
Native Conformation ◽  
Guanidinium Chloride ◽  
Original Activity ◽  
Limited Region ◽  
Low Concentrations ◽  
Two Stages ◽  
Inhibited Enzyme

The inactivation and unfolding of lactate dehydrogenase (LDH) during denaturation by guanidinium chloride (GuHCl) under diverse conditions have been compared. Unfolding of the native conformation, as monitored by fluorescence and c.d. measurements, occurs in two stages with increasing GuHCl concentrations, and the inactivation approximately coincides with, but slightly precedes, the first stage of unfolding. The enzyme is inhibited to about 60-70% of its original activity by cross-linking with glutaraldehyde or in the presence of 1 M-(NH4)2SO4, with its conformation stabilized as shown by the requirement for higher GuHCl concentrations to bring about both inactivation and unfolding. Low concentrations of GuHCl (0.2-0.4 M) activate the cross-linked and the (NH4)2SO4-inhibited enzyme back to the level of the native enzyme. For the enzyme stabilized by (NH4)2SO4 or by cross-linking with glutaraldehyde, inactivation occurs at a markedly lower GuHCl concentration than that required to bring about its first stage of unfolding. It is concluded that the active site of LDH is situated in a limited region relatively fragile in conformation as compared with the molecule as a whole. The GuHCl activation of LDH stabilized in (NH4)2SO4 or by cross-linking with glutaraldehyde suggests that this fragility and consequently flexibility of the active site is required for its catalytic activity.

Germination of Seeds From the Fruits of Thryptomene calycina (Myrtaceae)

1993 ◽  
Vol 41 (2) ◽  
pp. 263 ◽  
Author(s):  
DV Beardsell ◽  
RB Knox ◽  
EG Williams
Keyword(s):  
Gibberellic Acid ◽  
Sulphuric Acid ◽  
Seed Coat ◽  
Major Site ◽  
Low Concentrations ◽  
Viable Seeds ◽  
Insect Predation

Freshly fallen fruits of T. calycina contained seeds which were completely dormant; none germinated after 200 days at 20°C. Seeds excised with testas intact from fresh fruits were partially dormant; one-third germinated after 60 days. The dormancy of seeds in freshly fallen fruits was imposed jointly by the fruit and the seed. The major site of the dormancy was however the seed coat since tearing part of it away from seeds excised from fresh fruits resulted in rapid and complete germination. Fruits stored dry in a laboratory at 20°C for 90 days were partially dormant. Nicking the distal end of these fruits enhanced germination. Seeds excised from these laboratory stored fruits had 85 % germination, which indicated a reduction in the seed imposed dormancy. Germination of T. calycina was independent of light and, although the fruits contained large amounts of phenolic material this did not inhibit germination. Fruits weathered in the field for at least 2 years contained less viable seeds, presumably because of insect predation, but these all germinated within 50 days at 20°C. Brief washing of fruits in concentrated sulphuric acid increased germination. Germination was not enhanced by treatment with low concentrations of gibberellic acid in the presence or absence of cytokinin.

A correction to X-ray wave-length determination by plane crystal spectrograph

1962 ◽  
Vol 49 (8) ◽  
pp. 178-178
Author(s):  
A. N. Vishnoi ◽  
B. K. Agarwal
Keyword(s):  
Wave Length ◽  
X Ray ◽  
Length Determination

scholarly journals The Raman spectrum of rock-salt

1946 ◽  
Vol 187 (1009) ◽  
pp. 188-196 ◽  
Keyword(s):  
Raman Spectrum ◽  
Rock Salt ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Raman Effect ◽  
Frequency Shifts ◽  
Crystal Lattices ◽  
Absorption Frequency ◽  
Infra Red ◽  
Quartz Spectrograph

Using a non-luminescent crystal of rock-salt, a quartz spectrograph with a fine slit, and the 2536.5 A resonance radiations of mercury arc as exciter, the Raman effect in rock-salt has been studied. The spectrum exhibits nine distinct Raman lines with frequency shifts 135, 184, 202, 235, 258, 278, 314, 323 and 350 cm. -1 . The frequency shifts 235 and 184 cm. -1 representing conspicuous lines in the Raman spectrum agree as nearly as could be expected with the position of the two subsidiary infra-red absorption maxima observed by Barnes & Czerny with thin films of rock-salt. The principal infra-red absorption frequency of 163 cm. -1 is inactive in the Raman effect, but its octave is represented. The nature of the Raman spectrum to be expected is deduced on the basis of a theory due to Tamm, as also on the basis of another due to Fermi, the vibration spectrum of the rock-salt lattice being taken to be that worked out by Kellermann on the basis of the Born lattice dynamics. The results are altogether of a different nature from those actually observed experimentally in the present investigation. The conclusion is thus reached that the Born lattice dynamics does not correctly picture the vibration spectrum of the rock-salt lattice. On the other hand the observed facts, both in respect of Raman effect and infra-red absorption, fit into the theoretical picture provided by the dynamics of crystal lattices recently worked out by Sir C. V. Raman.

Reduction of Intra-oral Demineralization of Enamel after Single Exposures to Sodium Fluoride

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 867-870 ◽  
Author(s):  
S. Kashket ◽  
L.R. Lopez
Keyword(s):  
Protective Effect ◽  
Streptococcus Mutans ◽  
Sodium Fluoride ◽  
Experimental Period ◽  
Low Concentrations ◽  
Baseline Values ◽  
Two Stages ◽  
Bovine Enamel ◽  
Mineral Loss ◽  
Initial Elevation

Studies demonstrated the effects of single rinses with low concentrations of NaF on the intra-oral demineralization of enamel. Blocks of bovine enamel were covered with Streptococcus mutans IB1600, mounted in palatal appliances, and worn in the mouths of volunteers for specified times. Subjects rinsed with solutions of NaF, with or without sucrose. Demineralization was determined as changes in iodide penetrability (delta Ip) of the enamel, while the pH and F of the streptococcal plaque, and enamel F, were determined with ion-specific electrodes. Delta Ip was reduced by about 80% (from 14.5 ± 2.7 to 2.8 ± 2.3 units) when 250 μg F/mL was added to the sucrose rinse. Corresponding plaque pH's were 4.1 ± 0.5 and 4.2 ± 0.3, consistent with a lack of effect on bacterial acidogenesis. Protection against mineral loss was concentration-dependent. Administration of sucrose at different times after NaF revealed that the effect of F persisted for at least 60 min. Analyses of plaque F demonstrated an initial elevation and concentration within the cells, followed by a drop to stable, baseline values. Enamel F increased slowly to almost 500 μg/g enamel after 105 min. The protective effect of F appeared to be manifested in two stages, the first related to a high plaque F and the second to F that became incorporated into the enamel. Analysis of the data suggested that F was transferred from plaque to enamel during the experimental period.

INFLUENCE OF ORGANIC MATTER ON Re-Os DATING OF SULFIDES: INSIGHTS FROM THE GIANT JINDING SEDIMENT-HOSTED Zn-Pb DEPOSIT, CHINA

2021 ◽  
Author(s):  
Shiqiang Huang ◽  
Yucai Song ◽  
Limin Zhou ◽  
David L. Leach ◽  
Zhaoshan Chang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Inductively Coupled Plasma ◽  
Elemental Mapping ◽  
Bacterial Reduction ◽  
Inductively Coupled ◽  
Hydrocarbon Reservoir ◽  
Low Concentrations ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Two Stages

Abstract This study evaluates the effect of organic matter impurities on pyrite Re-Os dating, using the giant Jinding sediment-hosted Zn-Pb deposit in China as an example. The Jinding deposit is hosted in a Paleocene evaporite dome that was a hydrocarbon reservoir before mineralization. Pyrite in Jinding formed in two stages: pre-ore (py1) and syn-ore (py2). Two types of py1 are recognized, organic matter-free and organic matter-bearing. The organic matter-free py1 contains homogeneously distributed low concentrations of Re (<2.5 ppb) that yields an isochron age of 51 ± 1 Ma (mean square of weighted deviates [MSWD] = 3.2). This date is interpreted to be the age of py1 formation. The organic matter-bearing py1 contains organic matter inclusions trapped during py1 growth and synchronous with bacterial reduction of sulfate. Elemental mapping with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) shows that the organic matter inclusions have Re signals 1 to 4 orders of magnitude higher than those of pyrite, revealing that organic matter is the major host for Re. Such pyrite separates contain 37 to 1,145 ppb Re. The Re-Os data of organic matter-bearing py1 yield an isochron age of 72.9 ± 0.5 Ma (MSWD = 0.2). This age is older than the actual py1 formation age of 51 ± 1 Ma but overlaps with previously dated bitumen Re-Os isochron age of 68 ± 5 Ma at Jinding, indicating that organic matter inclusions can significantly influence the Re-Os dates of pyrite and likely other sulfides. This study demonstrates that in order to date sulfides formed in organic-rich environments using the Re-Os method, it is necessary to determine the distribution of Re in samples using detailed petrography and LA-ICP-MS trace element mapping plus spot analysis.

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