Joseph Sherma

Bio: Joseph Sherma is an academic researcher from Lafayette College. The author has contributed to research in topics: Biomphalaria glabrata & Thin-layer chromatography. The author has an hindex of 26, co-authored 441 publications receiving 4514 citations.

Handbook of Thin-Layer Chromatography

Abstract: Part 1 Principles and practice of thin-layer chromatography: basic techniques, materials and apparatus theory and mechanism of thin-layer chromatography optimization in TLC sorbents and precoated layers in TLC instrumental thin-layer chromatography gradient development in TLC overpressured layer chromatography detection, identification and documentation of chromatogen zones thin-layer chromatography coupled with mass spectrometry basic principles of optical quantitation in TLC preparative layer chromatography thin-layer radiochromatography rod TLC with flame ionization detection automation and robotics in planar chromatography. Part 2 Applications of thin-layer chromatography: amino acids and derivatives peptides and proteins antibiotics carbohydrates inorganics and organometallics enantiomeric separations lipids natural pigments pesticides pharmaceuticals and drugs phenols, aromatic acids and indoles nucleic acid derivatives steroids synthetic dyes toxins hydrophilic vitamins liphophilic vitamins.

Thin Layer Chromatography in Phytochemistry

Abstract: Thin layer chromatography in phytochemistry , Thin layer chromatography in phytochemistry , کتابخانه دیجیتال جندی شاپور اهواز

Thin-Layer Chromatography: Techniques and Applications

Abstract: Part 1 General practices of TLC: introduction and history mechanism and theory sorbents, layers, and precoated plates obtaining material for TLC and sample preparation application of samples solvent systems development techniques detection and visualization qualitative evaluation and documentation quantification reproducibility of results preparative TLC radiochemical techniques. Part 2 Applications of TLC to different compound types. basic TLC design and TLC of organic dyes lipids amino acids carbohydrates natural pigments vitamins nucleic acid derivatives steroids and terpinoids pharmaceuticals miscellaneous directory of manufacturers and suppliers of TLC instruments plates and reagents.

Synthesis, Light Emission, Nanoaggregation, and Restricted Intramolecular Rotation of 1,1-Substituted 2,3,4,5-Tetraphenylsiloles

Abstract: A series of ten 2,3,4,5-tetraphenylsiloles with different 1,1-substituents [XYSi(CPh)4] were prepared, and three of these, i.e., 1,1,2,3,4,5-hexaphenylsilole [X = Y = Ph (3)], 1-ethynyl-1,2,3,4,5-pentaphenylsilole [X = Ph, Y = C⋮CH (15)], and 1,1-bis(phenylethynyl)-2,3,4,5-tetraphenylsilole [X = Y = C⋮CPh (18)], were characterized crystallographically. The ground- and excited-states of the siloles were influenced by the inductive effect of the 1,1-substituents: with an increase in their electronegativity, the absorption and emission spectra of the siloles bathochromically shifted. A simple and reliable TLC-based method was developed for measurement of the solid-state luminescence spectra of the siloles. When molecularly dissolved in common solvents at room temperature, all the siloles were practically nonemissive (“off”). When poor solvents were added, the silole molecules clustered into nanoaggregates, which turned the emission “on” and boosted the photoluminescence quantum yields by up to 2 orders of m...

Protecting against water loss: analysis of the barrier properties of plant cuticles

Abstract: The cuticle is the major barrier against uncontrolled water loss from leaves, fruits and other primary parts of higher plants. More than 100 mean values for water permeabilities determined with isolated leaf and fruit cuticles from 61 plant species are compiled and discussed in relation to plant organ, natural habitat and morphology. The maximum barrier properties of plant cuticles exceed that of synthetic polymeric films of equal thickness. Cuticular water permeability is not correlated to the thickness of the cuticle or to wax coverage. Relationships between cuticular permeability, wax composition and physical properties of the cuticle are evaluated. Cuticular permeability to water increases on the average by a factor of 2 when leaf surface temperature is raised from 15 degrees C to 35 degrees C. Organic compounds of anthropogenic and biogenic origin may enhance cuticular permeability. The pathway taken by water across the cuticular transport barrier is reviewed. The conclusion from this discussion is that the bulk of water diffuses as single molecules across a lipophilic barrier while a minor fraction travels along polar pores. Open questions concerning the mechanistic understanding of the plant cuticular transport barrier and the role the plant cuticle plays in ensuring the survival and reproductive success of an individual plant are indicated.

Research advances in the use of tetrapyrrolic photosensitizers for photodynamic therapy.

Abstract: Photodynamic therapy (PDT) is a promising new treatment modality for several diseases, most notably cancer. In PDT, light, O2, and a photosensitizing drug are combined to produce a selective therapeutic effect. Lately, there has been active research on new photosensitizer candidates, because the most commonly used porphyrin photosensitizers are far from ideal with respect to PDT. Finding a suitable photosensitizer is crucial in improving the efficacy of PDT. Recent synthetic activity has created such a great number of potential photosensitizers for PDT that it is difficult to decide which ones are suitable for which pathological conditions, such as various cancer species. To facilitate the choice of photosensitizer, this review presents a thorough survey of the photophysical and chemical properties of the developed tetrapyrrolic photosensitizers. Special attention is paid to the singlet-oxygen yield (ΦΔ) of each photosensitizer, because it is one of the most important photodynamic parameters in PDT. Also, in the survey, emphasis is placed on those photosensitizers that can easily be prepared by partial syntheses starting from the abundant natural precursors, protoheme and the chlorophylls. Such emphasis is justified by economical and environmental reasons. Several of the most promising photosensitizer candidates are chlorins or bacteriochlorins. Consequently, chlorophyll-related chlorins, whose ΦΔ have been determined, are discussed in detail as potential photosensitizers for PDT. Finally, PDT is briefly discussed as a treatment modality, including its clinical aspects, light sources, targeting of the photosensitizer, and opportunities.

Antioxidant Activity of the Main Phenolic Compounds Isolated from Hot Pepper Fruit (Capsicum annuum L.)

Abstract: Four cultivars (Bronowicka Ostra, Cyklon, Tornado, and Tajfun) of pepper fruit Capsicum annuum L. were studied for phenolics contents and antioxidant activity. Two fractions of phenolics, flavonoids (with phenolic acids) and capsaicinoids, were isolated from the pericarp of pepper fruit at two growth stages (green and red) and were studied for their antioxidant capacity. Both fractions from red fruits had higher activities than those from green fruits. A comparison of the capsaicinoid fraction with the flavonoid and phenolic acid fraction from red fruit with respect to their antioxidant activity gave similar results. Phenolic compounds were separated and quantified by LC and HPLC. Contents of nine compounds were determined in the flavonoid and phenolic acid fraction: trans-p-feruloyl-β-d-glucopyranoside, trans-p-sinapoyl-β-d-glucopyranoside, quercetin 3-O-α-l-rhamnopyranoside-7-O-β-d-glucopyranoside, trans-p-ferulyl alcohol-4-O-[6-(2-methyl-3-hydroxypropionyl] glucopyranoside, luteolin 6-C-β-d-glucopyran...