scholarly journals Acid-catalyzed transformation of cassane diterpenoids from Caesalpinia bonduc to aromatic derivatives

RSC Advances ◽  
2021 ◽  
Vol 11 (36) ◽  
pp. 22070-22078
Author(s):  
Ting Liu ◽  
Zunxi Ning ◽  
Yan Yin ◽  
Shizhou Qi ◽  
Huiyuan Gao
Keyword(s):  
Uv Light ◽  
Acid Catalyzed ◽  
P Transformations

Transformations of cassane diterpenoids from Caesalpinia bonduc into aromatic derivatives, either in CDCl3 or in CHCl3 irradiated with UV light or catalyzed by AlCl3, were described.

Tetrazole 5-Acetic Acid Catalyzed Synthesis and Photophysical Study of 2-Aryl-2,3-dihydroquinolin-4(1H)-ones

2019 ◽  
Vol 16 (3) ◽  
pp. 176-184
Author(s):  
Mohabul A. Mondal ◽  
Abdul Ashik Khan ◽  
Kanchan Mitra
Keyword(s):  
Acetic Acid ◽  
Uv Light ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Mechanistic Study ◽  
Fluorescence Emission Spectra ◽  
Initial Activation ◽  
Photophysical Study ◽  
Acid Catalyzed ◽  
Yellowish White

1H-Tetrazole 5-acetic acid (TAA) has been explored as a new organocatalyst for the synthesis of 2-aryl-2,3-dihydroquinolin-4(1H)-ones derivatives from 2’-aminoacetophenone under solventfree conditions. The method described herein is covenient and the catalyst could be reused. Mechanistic study of the reaction revealed that the reaction passing through initial activation of the aldehyde by the catalyst and the C-C bond formed through the intermolecular pathway. The synthesized compounds exhibit yellowish-white fluorescence when exposed to 350 nm UV light. Optical properties such as absorption and fluorescence emission spectra were monitored in methanol. Fluorescence emission properties in different solvents with different polarity indicate solvatochromic characteristics of the probes.

scholarly journals Photooxidation of cyclohexene in the presence of SO<sub>2</sub>: SOA yield and chemical composition

2017 ◽  
Author(s):  
Shijie Liu ◽  
Long Jia ◽  
Yongfu Xu ◽  
Narcisse T. Tsona ◽  
Shuangshuang Ge ◽  
...  
Keyword(s):  
Urban Areas ◽  
Uv Light ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Atmospheric Environment ◽  
Oh Radicals ◽  
Competitive Reaction ◽  
Acid Catalyzed ◽  
Complementary Techniques ◽  
So2 Concentration

Abstract. Secondary organic aerosol (SOA) formation from cyclohexene/NOx system with various SO2 concentrations under UV light was studied to understand the effects of cyclic alkenes on the atmospheric environment in polluted urban areas. A clear decrease at first and then increase of the SOA yield was found with increasing SO2 concentrations. The lowest SOA yield was obtained when initial SO2 concentration was in the range of 30–40 ppb, while higher SOA yield compared to that without SO2 could not be obtained until the initial SO2 concentration was higher than 85 ppb. SOA formation was enhanced by the acid-catalyzed heterogeneous reactions, which lead to an increase in the total organic aerosol mass. The competitive reaction of OH radicals with SO2 and VOCs was the reason for the SOA yield decrease even under acidic conditions. The competitive reaction was an important factor for SOA yield and it should not be neglected in photooxidation, especially when acid-catalyzed mechanism could not significantly improve SOA yield. The composition of organic compounds in SOA was measured using several complementary techniques including Fourier transform infrared (FTIR) spectrometer, ion chromatograph (IC) and electrospray ionization high-resolution quadrupole mass spectrometer (ESI-HR-MS). We present the first evidence that organosulfates were produced from the photooxidation of cyclohexene in the presence of SO2.

Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

1992 ◽  
Vol 50 (2) ◽  
pp. 1104-1105
Author(s):  
Debby A. Jennings ◽  
Michael J. Morykwas ◽  
Louis C. Argenta
Keyword(s):  
Electron Microscopy ◽  
Cell Suspension ◽  
Single Cell ◽  
Chronic Wounds ◽  
Mechanical Stability ◽  
Uv Light ◽  
Type I ◽  
Single Cell Suspension ◽  
Collagen Substrate ◽  
Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

Immunolabelling of glomerular deposits in kidney biopsies routinely fixed in glutaraldehyde

1989 ◽  
Vol 47 ◽  
pp. 910-911
Author(s):  
Ś Lhoták ◽  
I. Alexopoulou ◽  
G. T. Simon
Keyword(s):  
Uv Light ◽  
Kidney Diseases ◽  
Light Chains ◽  
Microscopical Level ◽  
Accurate Identification ◽  
Light Microscopical Level ◽  
Dense Deposits ◽  
Cacodylate Buffer ◽  
Glomerular Deposits ◽  
Prognostic Importance

Various kidney diseases are characterized by the presence of dense deposits in the glomeruli. The type(s) of immunoglobulins (Igs) present in the dense deposits are characteristic of the disease. The accurate Identification of the deposits is therefore of utmost diagnostic and prognostic importance. Immunofluorescence (IF) used routinely at the light microscopical level is unable to detect and characterize small deposits found in early stages of glomerulonephritis. Although conventional TEM is able to localize such deposits, it is not capable of determining their nature. It was therefore attempted to immunolabel at EM level IgG, IgA IgM, C3, fibrinogen and kappa and lambda Ig light chains commonly found in glomerular deposits on routinely fixed ( 2% glutaraldehyde (GA) in 0.1M cacodylate buffer) kidney biopsies.The unosmicated tissue was embedded in LR White resin polymerized by UV light at -10°C. A postembedding immunogold technique was employed

Acid Catalyzed Furan Ring Transposition

10.1039/sp768 ◽  
2014 ◽  
Author(s):  
Jamsheena V. ◽  
Ravindra Phatake
Keyword(s):  
Furan Ring ◽  
Acid Catalyzed

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Sign in / Sign up

Export Citation Format

Share Document