The DNA base cytosine is commonly methylated in the promoter regions of inactive genes, indicatin... more The DNA base cytosine is commonly methylated in the promoter regions of inactive genes, indicating that methylation serves as a mechanism of control of gene expression. Methylated cytosine can also be oxidized to form other bases such as 5-formylcytosine, a reactive molecule. Molecules such as 1,3-propanediol, a compound commonly found in antifreeze and textiles, could react with the formyl group of 5-fC to form a cyclic acetal lesion
OWIN is a fairly new specification for modelling a HTTP server API for hosting web applications. ... more OWIN is a fairly new specification for modelling a HTTP server API for hosting web applications. The intent is to decouple the host from the application with the goal of providing a simpler programming model with potentially better performance than traditional web servers. While OWIN is a specification, Katana is Microsoft's implementation of an OWIN host. In this session we will discuss OWIN, Katana and how to write applications and middleware that take advantage of this new and exciting hosting environment.
Modern web development means that more and more application code is running in the browser as Jav... more Modern web development means that more and more application code is running in the browser as JavaScript. This architectural shift requires us to change how we perform authentication and authorization. Fortunately, using modern protocols such as OpenID Connect you don't need to invent your own solution for this new environment. This session will show you the modern approach for browser-based JavaScript applications to authenticate users, and perform secure web api invocations. As you might expect, security is sufficiently complex and so even modern security comes with its own set of challenges. Luckily, we will show off some libraries that help manage this complexity so your application doesn't have to.
Entries from this database may be freely copied and distributed for non-commercial use, providing... more Entries from this database may be freely copied and distributed for non-commercial use, providing copied materials contain this notice:
Nitraria retusa Asch. is one of the native perennial halophyte species that belongs to the botani... more Nitraria retusa Asch. is one of the native perennial halophyte species that belongs to the botanical family Nitrariaceae (Zygophyllaceae). It is a resistant shrub that grows in steppes and saline deserts, distributed in North Africa and restricted to Algeria, Egypt, and Tunisia >1, 2@. Previous phytochemical studies on N. retusa have led to the identification of a variety of compounds that include mainly flavonoids and their corresponding glucosides >3-7@. Recently, the phytochemical study of a Jordanian Nitraria retusa led to the isolation of two new quinazoline alkaloids, namely 5,7-dihydroxy-3-deoxyvasicine and 7-hydroxy-3-deoxy-1-vasiciene together with the known O-acetylnitraraine >8@. Due to our continuing interest in the chemical diversity of plants belonging to the Nitraria genus >9, 10@, we investigated the aerial parts of N. retusa growing in Egypt. Thus, we report herein the isolation and identification of three known compounds: two aromatics, vanillamide (1) and PABA (2), and one lignan, (+)-epi-syringaresinol (3). The description of the above-mentioned metabolites is noteworthy, as they have hitherto never been encountered in Nitraria species. Although the Nitraria genus is known to be rich in terms of diversity of alkaloids if not amounts, the alkaloidic extraction of the Egyptian N. retusa afforded only a small amount of material compared to its Jordanian congener. Furthermore, when the alkaloid extract was tested for the presence of alkaloids using Mayercs and Dragendorffcs reagents, the tests were negative. The absence of alkaloids in the so-called "alkaloidic extract" caught our attention and led us to analyze the methanolic one. Its extracted UV and MS data indicated characteristic evidences reminiscent of tricyclic quinazoline alkaloids >11@. Therefore, the putative detection of alkaloids in the methanolic extract may explain their absence in the alkaloid one. Indeed, due to their low basicity, alkaloids of the Egyptian N. retusa could not be extracted by the classical alkaloid extraction. On the other hand, the putative MS-based detection of the aforementioned tricylic quinazoline alkaloids in the methanolic extract of N. retusa is not an unexpected feature, because they were also identified in N. schoberi >10@, N. sibirica >12@ and N. komarovii >13@. Moreover, the distribution in Nature of the tricyclic quinazoline alkaloids, biosynthetically derived from anthranilic acid, is not restricted by the frameworks of any one or more taxonomic units. They are found most often in plants of the genera Peganum, Galega, Adhadota, Nitraria, Mackinlaya, etc. >14@. General. Optical rotations were measured at 25qC on an Anton Paar MCP200 polarimeter. UV spectra were recorded on a PerkinElmer Lambda 5 spectrophotometer. IR spectra were recorded with a Vector 22 Bruker spectrometer. The NMR spectra were recorded on Bruker AM-300 (300 MHz), AM-400 (400 MHz) apparatus using DMSO-d 6 , CD 3 OD, as solvents. HR-ESI-MS and LC/MS were run on a Thermoquest TLM LCQ Deca ion-trap spectrometer with an XBridge analytical C 18 column (150 u 2.1 mm; 3.5 Pm, Waters) and a preparative (150 u 19 mm, 5 Pm, Waters). Sunfire preparative C 18 columns (150 u 30 mm; i.d. 5 Pm, Waters) was used for preparative HPLC separations using a Waters Delta Prep column equipped with a binary pump (Waters 2525) and a UV-visible diode array detector (190-600 nm, Waters 2996). All other chemicals and solvents were purchased from Aldrich and SDS (France).
This thesis is dedicated to my family, especially my parents, for their constant support and enco... more This thesis is dedicated to my family, especially my parents, for their constant support and encouragement throughout this process. DNA Lesions Produced from the Reaction of Environmental Toxins and 5-Formylcytosine and their Effects on DNA Replication.
A total of 1,052 bacteria and 828 yeasts were isolated from the surface flora of 6 batches of Gub... more A total of 1,052 bacteria and 828 yeasts were isolated from the surface flora of 6 batches of Gubbeen cheese made in 1996-1997 and 2002-2003. Stability of the microflora was evaluated over time and also during ripening at 4, 10, and 16 d (batches 4, 5, and 6) or at 4, 16, 23, and 37 d (batches 1, 2, and 3). Bacteria were identified using pulsed-field gel electrophoresis, repetitive extragenic palindromic-PCR, and 16S rRNA gene sequencing, and yeasts were identified by Fourier transform infrared spectroscopy. The bacteria included at least 17 species, of which the most common were Staphylococcus saprophyticus (316 isolates), Corynebacterium casei (248 isolates), Brevibacterium aurantiacum (187 isolates), Corynebacterium variabile (146 isolates), Microbacterium gubbeenense (55 isolates), Staphylococcus equorum/cohnii (31 isolates), and Psychrobacter spp. (26 isolates). The most common yeasts were Debaryomyces hansenii (624 isolates), Candida catenulata (135 isolates), and Candida lusitaniae (62 isolates). In all batches of cheese except batch 2, a progression of bacteria was observed, with staphylococci dominating the early stages of ripening and coryneforms the later stages. No progression of yeast was found. Pulsed-field gel electrophoresis showed that several different strains of the 5 important species of bacteria were present, but generally only one predominated. The commercial strains used for smearing the cheese were recovered, but only in very small numbers early in ripening. Four species, B. aurantiacum, C. casei, C. variabile, and Staph. saprophyticus, were found on all batches of cheese, but their relative importance varied considerably. The results imply that significant variation occurs in the surface microflora of cheese.
Fractal error is an image processing metric that can be used to locate man-made features in aeria... more Fractal error is an image processing metric that can be used to locate man-made features in aerial images. The metric can aid photointerpreters in locating targets in aerial reconnaissance images. Fractal error was developed for this purpose by Cooper et al. [1]. Since the development, Jansing et al. [2] have shown that the fractal error metric also works well for extracting features in synthetic aperture radar (SAR) images. Jansing et al. [3] have also shown that the fractal error metric is useful for locating edge pixels in industrial images. The fractal error metric has a wide range of applications; however, some applications require real-time image analysis. The main disadvantage of the fractal error algorithm is that it can take several seconds to compute on large images. Therefore, it is desirable to create an approximation of fractal error to provide real-time image analysis. This paper presents two novel approximations of fractal error using a genetic algorithm and a neural network. The results obtained using the approximations are compared with those obtained from the fractal error algorithm. Results from the neural network and the genetic algorithm are compared with one another. The neural network provides an accurate representation of fractal error, while the genetic algorithm does in fact preserve all of the desired features of the original fractal error image. The genetic algorithm has been shown to be computationally faster than the neural network. Future work will consist of training a functional link neural network to improve computation time, and developing a genetic programming technique to evolve the mathematical structure and weights for a better fractal error approximation.
Page 148. THE EFFECTS OF INSTRUCTOR IMMEDIA CY BEHA VIORS IN ONLINE LEARNING ENVIRONMENTS Maria S... more Page 148. THE EFFECTS OF INSTRUCTOR IMMEDIA CY BEHA VIORS IN ONLINE LEARNING ENVIRONMENTS Maria Schutt San Diego State University Brock S. Allen and Mark A. Laumakis San Diego State University Previous ...
Two strains, Enterococcus faecium RZS C5 and E. faecium DPC 1146, produce listericidal bacterioci... more Two strains, Enterococcus faecium RZS C5 and E. faecium DPC 1146, produce listericidal bacteriocins, so-called enterocins. E. faecium RZS C5 was studied during batch fermentation in both a complex medium (MRS) and in milk to understand the influence of environmental factors, characteristic for milk and cheese, on both growth and bacteriocin production. Fermentation conditions were chosen in view of the applicability of in situ enterocin production during Cheddar cheese production. Enterocin production by E. faecium RZS C5 in MRS started in the early logarithmic growth phase, and enterocin activity decreased during the stationary phase. The effect of pH on enterocin production and decrease of activity was as intense as the effect on bacterial growth. Higher enterocin production took place at pH 5.5 compared with pH 6.5. The use of lactose instead of glucose increased the production of enterocin, and at higher lactose concentration, production increased more and loss of activity decreased. The production in skimmed milk compared to MRS was lower and was detected mainly in the stationary phase. When casein hydrolysate was added to the milk, enterocin production was higher and started earlier, indicating the importance of an additional nitrogen source for growth of E. faecium in milk. For co-cultures of E. faecium RZS C5 with the starters used during Cheddar cheese manufacture, no enterocin activity was detected during the milk fermentation. Furthermore, the applicability of E. faecium RZS C5 and E. faecium DPC 1146 strains was tested in Cheddar cheese manufacture on pilot scale. Enterocin production took place from the beginning of the cheese manufacturing and was stable during the whole ripening phase of the cheese. This indicates that both an early and late contamination of the milk or cheese can be combated with a stable, in situ enterocin production. The use of such a co-culture is an additional safety provision beyond good manufacturing practices.
The mechanism of biological photosensitization induced by furocoumarins (psoralens) has been inve... more The mechanism of biological photosensitization induced by furocoumarins (psoralens) has been investigated. Psoralen and other furocoumarins were found to exhibit fluorescence and to undergo electronic transitions involving singlet → triplet inter-combinations. The wavelengths emitted during phosphorescence were longer than those emitted during fluorescence. The biologically active and inactive compounds studied showed phosphorescence in the region of 460–470 and 500–525 mμ, respectively. Solutions of three psoralen derivatives (i.e., psoralen, 8-methoxypsoralen and 4,5′-dihydro-5-ethylcarbamyl-8-methoxypsoralen) in various solvents were irradiated with ultraviolet light (wavelengths greater than 310 mμ) at the temperature of liquid oxygen and examined with an electron spin-resonance spectrometer for free-radical formation. In the presence of either psoralen or 8-methoxypsoralen substantial electron-resonance signals were produced in solvent systems such as alcohol, alcohol plus water and glycerol plus water. Smaller signals were observed when water, glycerol and benzene were used alone as solvetns. The electron-resonance spectra of psoralen and 8-methoxypsoralen in alcohol solvents differed markedly from those of the same substances in solvents containing water. The biologically inactive derivative, 4′5′-dihydro-5-ethylcarbamyl-8-methoxypsoralen, produced weak free-radical signals in ethanol, but failed to produce signals in several other solvents. This study indicates that the reactive species in the biological photosensitization induced by psoralens is the triplet state of the sensitizing molecule. Exciation of the psoralen molecule to the triplet state may lead to free-radical formation. The mechanism of biological photosensitization appears to involve excitation of molecules to a triplet state and generation of free radicals which eventually evoke biological changes in the irradiated system.
The electron spin resonances of CaZliphora puparia, of Sepia ink, of human hair, and of 3,4-dihyd... more The electron spin resonances of CaZliphora puparia, of Sepia ink, of human hair, and of 3,4-dihydroxyphenylalanine melanin have been determined. The pigment in each case displays absorption with g = 2.003 f .OOl. The free radical property of these melanins is ascribed to a stabilized semiquinonoid form of the polymeric pigment.
We live in an era when everyday activities are shaped by en-vironments that are not only artifici... more We live in an era when everyday activities are shaped by en-vironments that are not only artificialalmost half of human-ity lives in citiesbut also mediated. Emotional and cognitive activities in all levels and segments of society are increasingly vested in information-rich ...
We live in an era when everyday activities are shaped by en-vironments that are not only artifici... more We live in an era when everyday activities are shaped by en-vironments that are not only artificialalmost half of human-ity lives in citiesbut also mediated. Emotional and cognitive activities in all levels and segments of society are increasingly vested in information-rich ...
The DNA base cytosine is commonly methylated in the promoter regions of inactive genes, indicatin... more The DNA base cytosine is commonly methylated in the promoter regions of inactive genes, indicating that methylation serves as a mechanism of control of gene expression. Methylated cytosine can also be oxidized to form other bases such as 5-formylcytosine, a reactive molecule. Molecules such as 1,3-propanediol, a compound commonly found in antifreeze and textiles, could react with the formyl group of 5-fC to form a cyclic acetal lesion
OWIN is a fairly new specification for modelling a HTTP server API for hosting web applications. ... more OWIN is a fairly new specification for modelling a HTTP server API for hosting web applications. The intent is to decouple the host from the application with the goal of providing a simpler programming model with potentially better performance than traditional web servers. While OWIN is a specification, Katana is Microsoft's implementation of an OWIN host. In this session we will discuss OWIN, Katana and how to write applications and middleware that take advantage of this new and exciting hosting environment.
Modern web development means that more and more application code is running in the browser as Jav... more Modern web development means that more and more application code is running in the browser as JavaScript. This architectural shift requires us to change how we perform authentication and authorization. Fortunately, using modern protocols such as OpenID Connect you don't need to invent your own solution for this new environment. This session will show you the modern approach for browser-based JavaScript applications to authenticate users, and perform secure web api invocations. As you might expect, security is sufficiently complex and so even modern security comes with its own set of challenges. Luckily, we will show off some libraries that help manage this complexity so your application doesn't have to.
Entries from this database may be freely copied and distributed for non-commercial use, providing... more Entries from this database may be freely copied and distributed for non-commercial use, providing copied materials contain this notice:
Nitraria retusa Asch. is one of the native perennial halophyte species that belongs to the botani... more Nitraria retusa Asch. is one of the native perennial halophyte species that belongs to the botanical family Nitrariaceae (Zygophyllaceae). It is a resistant shrub that grows in steppes and saline deserts, distributed in North Africa and restricted to Algeria, Egypt, and Tunisia >1, 2@. Previous phytochemical studies on N. retusa have led to the identification of a variety of compounds that include mainly flavonoids and their corresponding glucosides >3-7@. Recently, the phytochemical study of a Jordanian Nitraria retusa led to the isolation of two new quinazoline alkaloids, namely 5,7-dihydroxy-3-deoxyvasicine and 7-hydroxy-3-deoxy-1-vasiciene together with the known O-acetylnitraraine >8@. Due to our continuing interest in the chemical diversity of plants belonging to the Nitraria genus >9, 10@, we investigated the aerial parts of N. retusa growing in Egypt. Thus, we report herein the isolation and identification of three known compounds: two aromatics, vanillamide (1) and PABA (2), and one lignan, (+)-epi-syringaresinol (3). The description of the above-mentioned metabolites is noteworthy, as they have hitherto never been encountered in Nitraria species. Although the Nitraria genus is known to be rich in terms of diversity of alkaloids if not amounts, the alkaloidic extraction of the Egyptian N. retusa afforded only a small amount of material compared to its Jordanian congener. Furthermore, when the alkaloid extract was tested for the presence of alkaloids using Mayercs and Dragendorffcs reagents, the tests were negative. The absence of alkaloids in the so-called "alkaloidic extract" caught our attention and led us to analyze the methanolic one. Its extracted UV and MS data indicated characteristic evidences reminiscent of tricyclic quinazoline alkaloids >11@. Therefore, the putative detection of alkaloids in the methanolic extract may explain their absence in the alkaloid one. Indeed, due to their low basicity, alkaloids of the Egyptian N. retusa could not be extracted by the classical alkaloid extraction. On the other hand, the putative MS-based detection of the aforementioned tricylic quinazoline alkaloids in the methanolic extract of N. retusa is not an unexpected feature, because they were also identified in N. schoberi >10@, N. sibirica >12@ and N. komarovii >13@. Moreover, the distribution in Nature of the tricyclic quinazoline alkaloids, biosynthetically derived from anthranilic acid, is not restricted by the frameworks of any one or more taxonomic units. They are found most often in plants of the genera Peganum, Galega, Adhadota, Nitraria, Mackinlaya, etc. >14@. General. Optical rotations were measured at 25qC on an Anton Paar MCP200 polarimeter. UV spectra were recorded on a PerkinElmer Lambda 5 spectrophotometer. IR spectra were recorded with a Vector 22 Bruker spectrometer. The NMR spectra were recorded on Bruker AM-300 (300 MHz), AM-400 (400 MHz) apparatus using DMSO-d 6 , CD 3 OD, as solvents. HR-ESI-MS and LC/MS were run on a Thermoquest TLM LCQ Deca ion-trap spectrometer with an XBridge analytical C 18 column (150 u 2.1 mm; 3.5 Pm, Waters) and a preparative (150 u 19 mm, 5 Pm, Waters). Sunfire preparative C 18 columns (150 u 30 mm; i.d. 5 Pm, Waters) was used for preparative HPLC separations using a Waters Delta Prep column equipped with a binary pump (Waters 2525) and a UV-visible diode array detector (190-600 nm, Waters 2996). All other chemicals and solvents were purchased from Aldrich and SDS (France).
This thesis is dedicated to my family, especially my parents, for their constant support and enco... more This thesis is dedicated to my family, especially my parents, for their constant support and encouragement throughout this process. DNA Lesions Produced from the Reaction of Environmental Toxins and 5-Formylcytosine and their Effects on DNA Replication.
A total of 1,052 bacteria and 828 yeasts were isolated from the surface flora of 6 batches of Gub... more A total of 1,052 bacteria and 828 yeasts were isolated from the surface flora of 6 batches of Gubbeen cheese made in 1996-1997 and 2002-2003. Stability of the microflora was evaluated over time and also during ripening at 4, 10, and 16 d (batches 4, 5, and 6) or at 4, 16, 23, and 37 d (batches 1, 2, and 3). Bacteria were identified using pulsed-field gel electrophoresis, repetitive extragenic palindromic-PCR, and 16S rRNA gene sequencing, and yeasts were identified by Fourier transform infrared spectroscopy. The bacteria included at least 17 species, of which the most common were Staphylococcus saprophyticus (316 isolates), Corynebacterium casei (248 isolates), Brevibacterium aurantiacum (187 isolates), Corynebacterium variabile (146 isolates), Microbacterium gubbeenense (55 isolates), Staphylococcus equorum/cohnii (31 isolates), and Psychrobacter spp. (26 isolates). The most common yeasts were Debaryomyces hansenii (624 isolates), Candida catenulata (135 isolates), and Candida lusitaniae (62 isolates). In all batches of cheese except batch 2, a progression of bacteria was observed, with staphylococci dominating the early stages of ripening and coryneforms the later stages. No progression of yeast was found. Pulsed-field gel electrophoresis showed that several different strains of the 5 important species of bacteria were present, but generally only one predominated. The commercial strains used for smearing the cheese were recovered, but only in very small numbers early in ripening. Four species, B. aurantiacum, C. casei, C. variabile, and Staph. saprophyticus, were found on all batches of cheese, but their relative importance varied considerably. The results imply that significant variation occurs in the surface microflora of cheese.
Fractal error is an image processing metric that can be used to locate man-made features in aeria... more Fractal error is an image processing metric that can be used to locate man-made features in aerial images. The metric can aid photointerpreters in locating targets in aerial reconnaissance images. Fractal error was developed for this purpose by Cooper et al. [1]. Since the development, Jansing et al. [2] have shown that the fractal error metric also works well for extracting features in synthetic aperture radar (SAR) images. Jansing et al. [3] have also shown that the fractal error metric is useful for locating edge pixels in industrial images. The fractal error metric has a wide range of applications; however, some applications require real-time image analysis. The main disadvantage of the fractal error algorithm is that it can take several seconds to compute on large images. Therefore, it is desirable to create an approximation of fractal error to provide real-time image analysis. This paper presents two novel approximations of fractal error using a genetic algorithm and a neural network. The results obtained using the approximations are compared with those obtained from the fractal error algorithm. Results from the neural network and the genetic algorithm are compared with one another. The neural network provides an accurate representation of fractal error, while the genetic algorithm does in fact preserve all of the desired features of the original fractal error image. The genetic algorithm has been shown to be computationally faster than the neural network. Future work will consist of training a functional link neural network to improve computation time, and developing a genetic programming technique to evolve the mathematical structure and weights for a better fractal error approximation.
Page 148. THE EFFECTS OF INSTRUCTOR IMMEDIA CY BEHA VIORS IN ONLINE LEARNING ENVIRONMENTS Maria S... more Page 148. THE EFFECTS OF INSTRUCTOR IMMEDIA CY BEHA VIORS IN ONLINE LEARNING ENVIRONMENTS Maria Schutt San Diego State University Brock S. Allen and Mark A. Laumakis San Diego State University Previous ...
Two strains, Enterococcus faecium RZS C5 and E. faecium DPC 1146, produce listericidal bacterioci... more Two strains, Enterococcus faecium RZS C5 and E. faecium DPC 1146, produce listericidal bacteriocins, so-called enterocins. E. faecium RZS C5 was studied during batch fermentation in both a complex medium (MRS) and in milk to understand the influence of environmental factors, characteristic for milk and cheese, on both growth and bacteriocin production. Fermentation conditions were chosen in view of the applicability of in situ enterocin production during Cheddar cheese production. Enterocin production by E. faecium RZS C5 in MRS started in the early logarithmic growth phase, and enterocin activity decreased during the stationary phase. The effect of pH on enterocin production and decrease of activity was as intense as the effect on bacterial growth. Higher enterocin production took place at pH 5.5 compared with pH 6.5. The use of lactose instead of glucose increased the production of enterocin, and at higher lactose concentration, production increased more and loss of activity decreased. The production in skimmed milk compared to MRS was lower and was detected mainly in the stationary phase. When casein hydrolysate was added to the milk, enterocin production was higher and started earlier, indicating the importance of an additional nitrogen source for growth of E. faecium in milk. For co-cultures of E. faecium RZS C5 with the starters used during Cheddar cheese manufacture, no enterocin activity was detected during the milk fermentation. Furthermore, the applicability of E. faecium RZS C5 and E. faecium DPC 1146 strains was tested in Cheddar cheese manufacture on pilot scale. Enterocin production took place from the beginning of the cheese manufacturing and was stable during the whole ripening phase of the cheese. This indicates that both an early and late contamination of the milk or cheese can be combated with a stable, in situ enterocin production. The use of such a co-culture is an additional safety provision beyond good manufacturing practices.
The mechanism of biological photosensitization induced by furocoumarins (psoralens) has been inve... more The mechanism of biological photosensitization induced by furocoumarins (psoralens) has been investigated. Psoralen and other furocoumarins were found to exhibit fluorescence and to undergo electronic transitions involving singlet → triplet inter-combinations. The wavelengths emitted during phosphorescence were longer than those emitted during fluorescence. The biologically active and inactive compounds studied showed phosphorescence in the region of 460–470 and 500–525 mμ, respectively. Solutions of three psoralen derivatives (i.e., psoralen, 8-methoxypsoralen and 4,5′-dihydro-5-ethylcarbamyl-8-methoxypsoralen) in various solvents were irradiated with ultraviolet light (wavelengths greater than 310 mμ) at the temperature of liquid oxygen and examined with an electron spin-resonance spectrometer for free-radical formation. In the presence of either psoralen or 8-methoxypsoralen substantial electron-resonance signals were produced in solvent systems such as alcohol, alcohol plus water and glycerol plus water. Smaller signals were observed when water, glycerol and benzene were used alone as solvetns. The electron-resonance spectra of psoralen and 8-methoxypsoralen in alcohol solvents differed markedly from those of the same substances in solvents containing water. The biologically inactive derivative, 4′5′-dihydro-5-ethylcarbamyl-8-methoxypsoralen, produced weak free-radical signals in ethanol, but failed to produce signals in several other solvents. This study indicates that the reactive species in the biological photosensitization induced by psoralens is the triplet state of the sensitizing molecule. Exciation of the psoralen molecule to the triplet state may lead to free-radical formation. The mechanism of biological photosensitization appears to involve excitation of molecules to a triplet state and generation of free radicals which eventually evoke biological changes in the irradiated system.
The electron spin resonances of CaZliphora puparia, of Sepia ink, of human hair, and of 3,4-dihyd... more The electron spin resonances of CaZliphora puparia, of Sepia ink, of human hair, and of 3,4-dihydroxyphenylalanine melanin have been determined. The pigment in each case displays absorption with g = 2.003 f .OOl. The free radical property of these melanins is ascribed to a stabilized semiquinonoid form of the polymeric pigment.
We live in an era when everyday activities are shaped by en-vironments that are not only artifici... more We live in an era when everyday activities are shaped by en-vironments that are not only artificialalmost half of human-ity lives in citiesbut also mediated. Emotional and cognitive activities in all levels and segments of society are increasingly vested in information-rich ...
We live in an era when everyday activities are shaped by en-vironments that are not only artifici... more We live in an era when everyday activities are shaped by en-vironments that are not only artificialalmost half of human-ity lives in citiesbut also mediated. Emotional and cognitive activities in all levels and segments of society are increasingly vested in information-rich ...
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