scholarly journals Photodegradation Properties of Earlywood and Latewood Spruce Timber Surfaces

2021 ◽  
Vol 17 (1) ◽  
pp. 9-20
Author(s):  
Edina Preklet ◽  
László Tolvaj ◽  
Satoru Tsuchikawa ◽  
Dénes Varga
Keyword(s):  
Uv Irradiation ◽  
Lignin Degradation ◽  
Diffuse Reflectance ◽  
Difference Spectrum ◽  
Mercury Vapour ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Light Emitter ◽  
Mercury Vapour Lamp ◽  
The Difference ◽  
Guaiacyl Lignin

Spruce (Picea abies Karst.) samples were irradiated using an ultraviolet light emitter mercury vapour lamp. The examined specimen surfaces contained earlywood or latewood to determine the photodegradation properties of these two tissue types. The generated chemical changes were monitored by diffuse reflectance Fourier transformed infrared spectroscopy. The difference spectrum method was used to present absorption changes. The earlywood suffered considerably greater degradation than the latewood during the UV irradiation. Most of the lignin molecules in the examined surface layer degraded during the first 11 days of UV irradiation for both earlywood and latewood. Results demonstrated that two types of unconjugated carbonyls absorbing at 1705 and 1764 cm–1 wavenumbers were created during the photodegradation. Time dependence of the absorption changes showed correlation between the guaiacyl lignin degradation and the generation of unconjugated carbonyl group absorbing at 1764 cm–1 wavenumber.

Difference Spectrophotometric Estimation of Santonin

1984 ◽  
Vol 67 (5) ◽  
pp. 939-941
Author(s):  
Abdel-Azim M Habib ◽  
Abdalla A Omar ◽  
Taha M Sarg
Keyword(s):  
Difference Spectrum ◽  
Crude Drug ◽  
The Difference

Abstract Santonin gives a characteristic alkaline vs acidic difference spectrum. This was used for its estimation in pharmaceuticals and in the crude drug. Santonin was first extracted and purified through a specific partition procedure; then the difference absorbance was measured either at the maximum, 285 nm, or the minimum, 242 nm. The percentage of santonin can be calculated either by reference to the difference absorbance of a reference santonin sample, treated similarly, or by making use of the determined absorptivity. Measurement at the maximum is advisable, especially when the crude drug is assayed, because natural contaminants may interfere with the difference absorbance at the minimum.

The interaction of bovine milk caseins with the detergent sodium dodecyl sulphate. II. The effect of detergent binding on spectral properties of caseins

1970 ◽  
Vol 37 (2) ◽  
pp. 259-267 ◽  
Author(s):  
G. C. Cheeseman ◽  
Dorothy J. Knight
Keyword(s):  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Bovine Milk ◽  
Difference Spectrum ◽  
Temperature Dependent ◽  
Difference Spectra ◽  
Negative Change ◽  
Tryptophan Residues ◽  
Hydrophobic Binding ◽  
The Difference

SummaryThe dissociation of casein aggregates by the detergent sodium dodecyl sulphate (SDS) gave rise to difference spectra and these spectra were characteristic for each of the different types of casein. Increase in absorption by the chromophore groups, tyrosine and tryptophan, when αs1- and β-casein aggregates were dissociated indicated binding of the detergent at regions of the molecule containing these residues. A decrease in absorption when κ-casein was dissociated indicated that the tyrosine and tryptophan residues were not in the region of the molecule to which the detergent was bound and that in the κ-casein aggregate these residues were in a more hydrophobic environment. Peaks on the difference spectra were obtained at 280 and 288 nm for αs1-casein and 284 and 291 nm for β-casein and troughs at 278 and 286 nm for κ-casein. The difference spectrum reached a maximum value when the αsl- and β-casein aggregates were dissociated and the further binding of SDS did not alter this value. The large negative change in the difference spectrum of κ-casein did not occur until after most of the aggregates were dissociated and did not reach a maximum until binding with SDS was complete. The value obtained for ΔOD was found to be temperature-dependent for β-casein-SDS interaction, but not for αs1- and κ-casein. Changes in spectra were also observed when αs1- and κ-casein interacted to form aggregates. The data obtained confirmed the importance of hydrophobic binding in casein aggregate formation and indicated the possible involvement of tyrosine and tryptophan residues in this binding.

scholarly journals Structural Analysis of Yoked Chorionic Gonadotropin-Luteinizing Hormone Receptor Ectodomain Complexes by Circular Dichroic Spectroscopy

2003 ◽  
Vol 17 (7) ◽  
pp. 1192-1202 ◽  
Author(s):  
Gregory B. Fralish ◽  
Brian Dattilo ◽  
David Puett
Keyword(s):  
Chorionic Gonadotropin ◽  
Fusion Proteins ◽  
Homology Model ◽  
Difference Spectrum ◽  
Luteinizing Hormone Receptor ◽  
Amino Acid Residues ◽  
Single Chain ◽  
Glycoprotein Hormone ◽  
The Difference ◽  
Α Helix

Abstract Binding of the heterodimeric glycoprotein hormone, chorionic gonadotropin (CG), occurs to the heptahelical LH receptor N-terminal ectodomain (ECD), a large portion of which has been modeled as a leucine-rich repeat protein. In this study, we expressed and purified three single chain N-CG-ECD-C complexes, one comprising the full-length ECD, 1–341 (encoded by exons 1–10 and a portion of 11), and two C-terminal ECD deletion fragments, 1–294 (encoded by exons 1–10) and 1–180 (encoded by exons 1–7). The fusion proteins, including yoked CG (N-β-α-C), were characterized by Western blot analysis and circular dichroism (CD). Analysis of the CD spectra obtained on the CG-ECD fusion proteins, and of the difference spectrum of each after subtracting the CG contribution, yielded secondary structures consistent with a repeating β-strand/α-helix fold as predicted in the homology model. A marked decrease in helicity was observed when the C-terminal 47 amino acid residues were removed from the ECD. Removal of an additional 114 residues, i.e. the region encoded by exons 8–10, results in the loss of fewer helical residues. These results suggest that the hinge region of the ECD, predicted to contain only limited secondary structure, interacts with and stabilizes the ligand-occupied N-terminal portion. Furthermore, the results support a repeating fold, consistent with the proposed model for the LHR ECD.

scholarly journals Intercalibration of different light-traps and bulbs used in moth monitoring in northern Europe

1998 ◽  
Vol 9 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Reima Leinonen ◽  
Guy Söderman ◽  
Juhani Itämies ◽  
Seppo Rytkönen ◽  
Ilpo Rutanen
Keyword(s):  
The Other ◽  
Northern Europe ◽  
Mercury Vapour ◽  
Light Traps ◽  
Mercury Vapour Lamp ◽  
Species Being ◽  
Tungsten Lamp

Four different combinations of light-traps and bulbs were tested during the summer 1996 in Kainuu, northern Finland: a Jalas model with a 160-W (J/160W) blended light lamp or a 125-W (J/125W) mercury vapour lamp, a Ryrholm trap with a 125-W (R/125W) mercury vapour lamp and a Rothamsted trap with a 200-W tungsten lamp (G/200W). The traps were rotated between four sites every night, but were kept in the same position for the fifth night in order to prevent the possible influence of moonlight. The longest distance between the traps was 150m, and there was no direct visibility between any of them. Three orders were inspected, i.e. Lepidoptera, Coleoptera and Hemiptera, the total numbers of individuals and species being as follows: 20857/425, 862/101 and 1868/58. G/200W collected significantly fewer moths than the other traps. In some cases, J/125W collected significantly more moths and less species than the J/160W design. The R/125W design collected significantly more species than the J/160W design. Similar differences in the effectiveness of the lamps and traps were found in the case of Coleoptera and Hemiptera. Alpha diversities showed the same trend.

Photorearrangement of 2-cyanobicyclo[2.2.1]hept-2-ene. Observation of 1,2- and 1,3-sigmatropic shifts

1982 ◽  
Vol 60 (13) ◽  
pp. 1657-1663 ◽  
Author(s):  
Ikbal A. Akhtar ◽  
John J. McCullough ◽  
Susan Vaitekunas ◽  
Romolo Faggiani ◽  
Colin J. L. Lock
Keyword(s):  
Single Crystals ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Major Product ◽  
Molecular Structures ◽  
Lithium Aluminum ◽  
Mercury Vapour ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Mercury Vapour Lamp

Irradiation of 2-cyanobicyclo[2.2.1]hept-2-ene (2-cyanonorbornene, 4) in hexane, with the full arc of a mercury vapour lamp, gives the rearrangement products 1-cyanobicyclo[4.1.0]hept-2-ene 5 and 7-cyanotricyclo[4.1.0.03.7]heptane 6 in the ratio 20:1. These products were separated by preparative vpc. The structure of the major product 5 was determined by single crystal X-ray analysis. Reduction of 5 with lithium aluminum hydride gave the corresponding primary amine, which was converted to the p-bromobenzenesulfonamide 9, mp 150–151 °C, which gave single crystals from ethanol–water. The crystal and molecular structures are described. The minor product 6 was hydrogenated to give 7-cyanobicyclo[2.2. 1]heptane. Formation of 5 and 6 may involve concerted σ2s + π2s and σ2a + π2a processes respectively, which are photochemically allowed.

Diagnosis of Gulf War Illness Using Laser-Induced Spectra Acquired from Blood Samples

2021 ◽  
pp. 000370282110420
Author(s):  
Rosalba Gaudiuso ◽  
Sirui Chen ◽  
Efi Kokkotou ◽  
Lisa Conboy ◽  
Eric Jacobson ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Correct Diagnosis ◽  
Difference Spectrum ◽  
Gulf War ◽  
Classification Model ◽  
Control Group ◽  
Plasma Samples ◽  
Gulf War Illness ◽  
Breakdown Spectroscopy ◽  
The Difference

Gulf War illness (GWI) is a chronic illness with no known validated biomarkers that affects the lives of hundreds of thousands of people. As a result, there is an urgent need for the development of an untargeted and unbiased method to distinguish GWI patients from non-GWI patients. We report on the application of laser-induced breakdown spectroscopy (LIBS) to distinguish blood plasma samples from a group of subjects with GWI and from subjects with chronic low back pain as controls. We initially obtained LIBS data from blood plasma samples of four GWI patients and four non-GWI patients. We used an analytical method based on taking the difference between a mean LIBS spectrum obtained with those of GWI patients from the mean LIBS spectrum of those of the control group, to generate a “difference” spectrum for our classification model. This model was cross-validated using different numbers of differential LIBS emission peaks. A subset of 17 of the 82 atomic and ionic transitions that provided 70% of correct diagnosis was selected test in a blinded fashion using 10 additional samples and was found to yield 90% classification accuracy, 100% sensitivity, and 83.3% specificity. Of the 17 atomic and ionic transitions, eight could be assigned unambiguously to species of Na, K, and Fe.

scholarly journals The photographic efficiency of heterogeneous light

1921 ◽  
Vol 100 (703) ◽  
pp. 109-113 ◽  
Keyword(s):  
Absorption Coefficient ◽  
White Light ◽  
Photographic Plate ◽  
Silver Halide ◽  
Radiant Energy ◽  
Spectral Lines ◽  
Photographic Emulsion ◽  
Mercury Vapour ◽  
Mercury Vapour Lamp

There are some sources of illumination which are much more active photographically than others, and one of the most active of all artificial sources is the mercury vapour lamp. The energy of the radiation from this lamp is concentrated in a comparatively few spectral lines, and most of these are in that region of the spectrum which is the region of greatest absorption by the silver halide grains of which the photographic emulsion is composed. This, in itself, may be the complete explanation of the intense photographic activity of this particular illuminant, but the question arises as to whether the explanation is, in part, merely the fact that the light is concentrated into a few wave-lengths, apart altogether from any consideration of the absorption coefficient. In other words, a given quantity of radiant energy absorbed in the grains may give a greater photographic effect when it is all of one frequency than when it is a complex radiation such as white light. The object of the present paper is to discuss this question in the light of recent researches on the photographic plate.

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