scholarly journals Role of crystallography in pharmaceutical solid-form development

2021 ◽  
Vol 77 (a1) ◽  
pp. a201-a201
Author(s):  
Rajni Bhardwaj
Keyword(s):  
Solid Form ◽  
Form Development

scholarly journals Metamorphoses of malaria: the role of autophagy in parasite differentiation

2011 ◽  
Vol 51 ◽  
pp. 127-136 ◽  
Author(s):  
Isabelle Coppens
Keyword(s):  
Life Cycle ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Protozoan Parasites ◽  
Membrane Complex ◽  
Autophagic Process ◽  
Inner Membrane Complex ◽  
Form Development ◽  
High Degree

Several protozoan parasites undergo a complex life cycle that alternates between an invertebrate vector and a vertebrate host. Adaptations to these different environments by the parasites are achieved by drastic changes in their morphology and metabolism. The malaria parasites must be transmitted to a mammal from a mosquito as part of their life cycle. Upon entering the mammalian host, extracellular malaria sporozoites reach the liver and invade hepatocytes, wherein they meet the challenge of becoming replication-competent schizonts. During the process of conversion, the sporozoite selectively discards organelles that are unnecessary for the parasite growth in liver cells. Among the organelles that are cleared from the sporozoite are the micronemes, abundant secretory vesicles that facilitate the adhesion of the parasite to hepatocytes. Organelles specialized in sporozoite motility and structure, such as the inner membrane complex (a major component of the motile parasite's cytoskeleton), are also eliminated from converting parasites. The high degree of sophistication of the metamorphosis that occurs at the onset of the liver-form development cascade suggests that the observed changes must be multifactorial. Among the mechanisms implicated in the elimination of sporozoite organelles, the degradative process called autophagy contributes to the remodelling of the parasite interior and the production of replicative liver forms. In a broader context, the importance of the role played by autophagy during the differentiation of protozoan parasites that cycle between insects and vertebrates is nowadays clearly emerging. An exciting prospect derived from these observations is that the parasite proteins involved in the autophagic process may represent new targets for drug development.

Particle Engineering: Fundamentals of Particle Formation and Crystal Growth

MRS Bulletin ◽  
2006 ◽  
Vol 31 (11) ◽  
pp. 881-886 ◽  
Author(s):  
Alfred Y. Lee ◽  
Allan S. Myerson
Keyword(s):  
Crystal Growth ◽  
Dosage Form ◽  
Decisive Role ◽  
Product Performance ◽  
Particle Engineering ◽  
Particle Properties ◽  
Packing Arrangement ◽  
Form Development

AbstractThe engineering of particles with customized properties optimized for dosage form manufacture (tablet, capsule, ointment, etc.) has long been a goal of the pharmaceutical industry. Particles can be designed through modification in the size, morphology, and packing arrangement of the solids. The most common approach in achieving this is through crystallization. In this bottom-up process, the two main steps, nucleation and crystal growth, both play a decisive role in shaping the quality of the final crystalline product. In this review, the role of nucleation and crystal growth in controlling particle properties is discussed, and examples are provided that demonstrate the variation in solid-state properties as a function of size, habit (morphology), and internal structure of the particles. In addition, the role of particle properties in product performance and dosage form development of pharmaceuticals is also discussed.

Iodination of Organic Compounds with Elemental Iodine in the Presence of Hydrogen Peroxide in Ionic Liquid Media

2008 ◽  
Vol 61 (12) ◽  
pp. 946 ◽  
Author(s):  
Jasminka Pavlinac ◽  
Kenneth K. Laali ◽  
Marko Zupan ◽  
Stojan Stavber
Keyword(s):  
Hydrogen Peroxide ◽  
Ionic Liquid ◽  
Organic Compounds ◽  
Molar Ratio ◽  
Liquid Media ◽  
Reaction Conditions ◽  
Solid Form ◽  
Elemental Iodine ◽  
Solvent Free Reaction

Iodo-transformations using the reagent system I2/H2O2 were studied in the water miscible ionic liquid (IL) 1-butyl-3-methyl imidazolium tetrafluoroborate (bmimBF4) and in water immiscible IL, 1-butyl-3-methyl imidazolium hexafluorophosphate (bmimPF6). Two different forms of H2O2 as mediators of iodination were investigated, namely 30% aq. H2O2 and urea-H2O2 (UHP) in solid form. The role of the oxidant during the course of a reaction could be distinguished based on the amount of reagent required for the most efficient transformation. Two types of iodo-functionalizations through an electrophilic process were observed depending on the structure of the substrates. Whereas ring iodination took place in the case of dimethoxy- and trimethoxy-benzenes, with arylalkyl ketones the alkyl group α to the carbonyl was regioselectively iodinated. The results were further evaluated in comparison with iodination using the reagent system I2/H2O2 in water as medium, and under solvent-free reaction conditions, in terms of efficiency, selectivity, mechanism, and the ‘green’ aspects. The reusability/recycling of water immiscible bmimPF6 was investigated for 1,3,5-trimethoxy benzene (1b), which required a 1/0.5/0.6 molar ratio of substrat/I2/oxidant, and for 1,2,3-trimethoxy benzene (1f), which required a 1/1/1 ratio for complete iodine introduction. In addition, the efficiency of iodination was tested by varying the substrates, and employing the recycled hydrophobic IL bmimPF6.

The role of Douglas-fir stem sapwood and heartwood in the mechanical and physiological support of crowns and development of stem form

1981 ◽  
Vol 11 (3) ◽  
pp. 459-464 ◽  
Author(s):  
James N. Long ◽  
Frederick W. Smith ◽  
David R. M. Scott
Keyword(s):  
Douglas Fir ◽  
Mechanical Support ◽  
Principal Function ◽  
Stem Form ◽  
Cross Sectional ◽  
Sapwood Area ◽  
Large Trees ◽  
Uniform Resistance ◽  
Form Development

The mechanical and physiological support of a tree's crown is the principal function of its bole. A simple model for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) of different crown classes explains much of the observed differences in stem form development. Sapwood cross-sectional area at any height on the bole of the tree was found to be related linearly to the amount of foliage above that point; however, in large trees the sapwood area needed to supply transpiring foliage with water is insufficient to provide mechanical support. The combination of sapwood and heartwood was found to provide the stem form that would be expected to ensure uniform resistance to bending by the wind.

scholarly journals The potential of computed crystal energy landscapes to aid solid-form development

2016 ◽  
Vol 21 (6) ◽  
pp. 912-923 ◽  
Author(s):  
Sarah L. Price ◽  
Susan M. Reutzel-Edens
Keyword(s):  
Energy Landscapes ◽  
Solid Form ◽  
Form Development

SOLID FORM DEVELOPMENT FOR POORLY SOLUBLE COMPOUNDS

2019 ◽  
pp. 665-687
Author(s):  
Alessandra Mattei ◽  
Shuang Chen ◽  
Jie Chen ◽  
Ahmad Y. Sheikh
Keyword(s):  
Poorly Soluble ◽  
Solid Form ◽  
Form Development

scholarly journals Applying artificial precipitations to mitigate the melting of the Muz Taw Glacier, Sawir Mountains

2019 ◽  
Author(s):  
Feiteng Wang ◽  
Xiaoying Yue ◽  
Lin Wang ◽  
Huilin Li ◽  
Zhencai Du ◽  
...  
Keyword(s):  
Mass Loss ◽  
Surface Albedo ◽  
Weather Station ◽  
Air Mass ◽  
Individual Experiment ◽  
Before And After ◽  
Set Up ◽  
The Individual ◽  
Solid Form

Abstract. The Glaciers in the Sawir Mountains, Altai area, are characterized by higher latitudes and lower elevations. Influenced by the westerly circulation and the polar air mass, the precipitation is abundant and evenly distributed over the year in this area. However, a continuing and accelerating mass loss of glaciers has been in presence since 1959. To study the role of precipitation in mitigating the glacier’s melting, we carried out two artificial-precipitation experiments on the Muz Taw Glacier of the Sawir Mountains on 19 and 22 August 2018, respectively. We measured the albedo and MB at different sites along the glacier before and after the individual experiment. According to the records of the automatic weather station (AWS) set up at the equilibrium line (EL, 3400 m), the amount of precipitation was 6.2 mm and 12.4 mm water equivalent in solid form by the two experiments, respectively. Due to the artificial solid precipitations, the glacier’s surface albedo significantly increased in the mid-upper area, and the amounts of the mass loss decreased by 17 %. We also propose a possible mechanism describing the role of precipitation in mitigating the melting of the glacier.

scholarly journals Phytolith Formation in Plants: From Soil to Cell

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 249 ◽  
Author(s):  
Muhammad Amjad Nawaz ◽  
Alexander Mikhailovich Zakharenko ◽  
Ivan Vladimirovich Zemchenko ◽  
Muhammad Sajjad Haider ◽  
Muhammad Amjad Ali ◽  
...  
Keyword(s):  
Life Science ◽  
Biotic And Abiotic Stress ◽  
Plant Phylogeny ◽  
Silicon Transporter ◽  
Plant Body ◽  
Precise Understanding ◽  
Significant Research ◽  
Solid Form ◽  
Channel Type

Silica is deposited extra- and intracellularly in plants in solid form, as phytoliths. Phytoliths have emerged as accepted taxonomic tools and proxies for reconstructing ancient flora, agricultural economies, environment, and climate. The discovery of silicon transporter genes has aided in the understanding of the mechanism of silicon transport and deposition within the plant body and reconstructing plant phylogeny that is based on the ability of plants to accumulate silica. However, a precise understanding of the process of silica deposition and the formation of phytoliths is still an enigma and the information regarding the proteins that are involved in plant biosilicification is still scarce. With the observation of various shapes and morphologies of phytoliths, it is essential to understand which factors control this mechanism. During the last two decades, significant research has been done in this regard and silicon research has expanded as an Earth-life science superdiscipline. We review and integrate the recent knowledge and concepts on the uptake and transport of silica and its deposition as phytoliths in plants. We also discuss how different factors define the shape, size, and chemistry of the phytoliths and how biosilicification evolved in plants. The role of channel-type and efflux silicon transporters, proline-rich proteins, and siliplant1 protein in transport and deposition of silica is presented. The role of phytoliths against biotic and abiotic stress, as mechanical barriers, and their use as taxonomic tools and proxies, is highlighted.

Mechanisms of removal of heavy metals and arsenic from water by TiO2-heterogeneous photocatalysis

2015 ◽  
Vol 87 (6) ◽  
pp. 557-567 ◽  
Author(s):  
Marta I. Litter
Keyword(s):  
Direct Reduction ◽  
Ionic Species ◽  
Heterogeneous Photocatalysis ◽  
Semiconductor Surface ◽  
Simultaneous Treatment ◽  
Radical Oxidation ◽  
Photogenerated Electrons ◽  
Removal Of Heavy Metals ◽  
Solid Form

AbstractThis article is an overview of recent work performed in our laboratory on TiO2 heterogeneous photocatalysis of aqueous systems containing toxic forms of chromium, arsenic, lead, uranium and mercury. The cases of chromium and arsenic are treated in profundity. Photocatalytic treatments can convert the ionic species into their metallic solid form and deposit them over the semiconductor surface, or transform them into less toxic soluble species. When a transformation to the zerovalent state is possible, this allows the recovery of the metal from the waters, with an important economical return. Three types of mechanisms can be considered, all of them taking place through successive thermodynamically allowed monoelectronic electron transfer steps: (a) direct reduction by photogenerated electrons; (b) indirect reduction by intermediates generated by hole or hydroxyl radical oxidation of electron donors (reducing radicals); (c) oxidative removal by holes or hydroxyl radicals. Fundamentals of oxidative or reductive heterogeneous photocatalysis are described, with special emphasis on the role of organic donors present in the medium acting as synergists. This indicates the possibility of simultaneous treatment of pollutants of different chemical structure and properties present in the same medium.

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