Physical Bases of Work of Photo Receivers Based on Silicides
Elchin Ahmed Kerimov,
Sevinj Nadir Musaeva
Issue:
Volume 8, Issue 4, August 2020
Pages:
77-80
Received:
19 March 2020
Accepted:
24 April 2020
Published:
14 September 2020
Abstract: The creation of high-quality high-speed semiconductor devices and integrated circuits requires the introduction of new materials into the technology for their manufacture. The most promising of them are silicides-silicon compounds with more electropositive elements. These compounds can be obtained as a result of a solid phase reaction at a temperature in the range of about one to half the melting point of this metal on an absolute scale. Silicides have a high conductivity of a metallic nature, high temperature stability, and surpass in these properties any heavily doped semiconductor layer. The use of polysilicon as a material for gates and connecting lines providing a layer resistance of 20 Ohms/□ allowed us to reduce the minimum dimensions of the elements of devices to 25 microns. Methods were proposed for the formation of silicide films, as well as technological processes necessary for the manufacture of semiconductor devices and microcircuits with their application, which allowed us to start developing devices with a minimum element size of 1 μm and to begin their industrial production. The stable and reliable characteristics of platinum-silicon silicide (PtSi-Si) contacts have led to the widespread use of silicides as materials for ohmic contacts, gates in metal-oxide-semiconductor (MIS)-transistors, materials for storing optical information, photodetectors operating in IR-spectral regions, etc. The Si-2p band has an asymmetric shape; the structure of valence states differs from metallic ones.
Abstract: The creation of high-quality high-speed semiconductor devices and integrated circuits requires the introduction of new materials into the technology for their manufacture. The most promising of them are silicides-silicon compounds with more electropositive elements. These compounds can be obtained as a result of a solid phase reaction at a temperat...
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Inhibitory Effect and Antimicrobial Activity of Secondary Metabolites of Khaya Senegalensis (Desr.) A. Juss. (Meliaceae)
Yves Oscar Ditchou Nganso,
Emmanuella Marthe Satchet Tchana,
Alex Doutsing Kahouo,
Ange Gabrielle à Ngnoung Amang,
Kombo Abah,
Hermann Fomena,
Hamadou Mamoudou
Issue:
Volume 8, Issue 4, August 2020
Pages:
81-94
Received:
3 August 2020
Accepted:
21 August 2020
Published:
17 September 2020
Abstract: This present study investigates the in vitro inhibitory effect and antimicrobial activity of secondary metabolites isolated from the roots of Khaya senegalensis, a plant of the Meliaceae family. Khaya senegalensis is widely used in traditional medicine for the treatment of various illnesses such as: fever, stomach ache, diarrhea, dysentery and anemia. The chemical study of the extract with CH2Cl2-MeOH (1:1) led to the isolation of five compounds: Alphitolic acid (1); Epigouanic acid (2); Methyl angolensate (3); Rohituca-3 (4) and 5, 6, 7, 3′, 4′-pentamethoxyflavone or Sinensetin (5). Alphitolic acid (1), Rohituca-3 (4) and 5, 6, 7, 3′, 4′-pentamethoxyflavone or Sinensetin (5) were isolated from the roots of this plant for the first time. The structures of the isolated compounds have been elucidated on the basis of spectroscopic analysis and a comparison of their spectral data with those reported in the literature. The results of the antibiogram tests showed that the strain of Escherichia coli is sensitive to all the antibiotics tested except Ceftazidime, a Cephalosporin. The Staphylococcus aureus strain is resistant to almost all the antibiotics tested except Amikacin, an aminoglycoside. This is because the enzymes diffuse through the inter and intraspecific transmission of genes through a plasmid. The antibiogram made it possible to establish the sensitivity profile of the strains tested with regard to certain antibiotics. The antimicrobial tests carried out showed that the inhibitory effect of the compounds isolated from Khaya senegalensis on the four bacterial strains tested at the concentration of 25 mg/mL positively influenced at least one of the microbial strains. However, compounds 1, 2 and 3 did not show any bacterial growth inhibitory activity against Proteus vulgaris. MIC obtained for microbiological tests varied between 0.097 and 0.195 mg/mL for the most sensitive strains of Escherichia coli and Pseudomonas aeruginosa, which revealed the highest antibacterial powers. Furthermore, these results therefore show a great variability in the bacteriostatic qualities of the compounds with respect to the different strains. The two Gram-positive strains of Staphylococcus aureus are more sensitive than the other Gram-negative bacterial strains tested. From the antibacterial activity, it appears that the compounds isolated from this plant have a bactericidal activity against Escherichia coli and Pseudomonas aeruginosa. This bactericide could justify their use in herbal medicine against bacterial infections.
Abstract: This present study investigates the in vitro inhibitory effect and antimicrobial activity of secondary metabolites isolated from the roots of Khaya senegalensis, a plant of the Meliaceae family. Khaya senegalensis is widely used in traditional medicine for the treatment of various illnesses such as: fever, stomach ache, diarrhea, dysentery and anem...
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Evaluation of the Maturity of the Compost Produced at the Compost Production Site of the NGO ENPRO in Lomé (Togo) Using the UV-Visible Spectroscopy
Joël Mawuli Tamakloe,
Edem Komi Koledzi,
Sassou Megnassan,
Etsè Aziable
Issue:
Volume 8, Issue 4, August 2020
Pages:
95-101
Received:
18 August 2020
Accepted:
31 August 2020
Published:
17 September 2020
Abstract: Composting is a method of recovery of household solid waste. But to be useful to agriculture the compost resulting from this process must be mature. The objective of this study is to evaluate the maturity of three types of composts produced on the garbage composting unit of the NGO ENPRO in Lomé. Three types of compost (garbage, fruit waste, animal litter) were made in windrows for at least 3 months. The maturity of the composts was determined according to the basic chemical analysis, by UV-Visible spectroscopy. UV-visible spectroscopy performed on the three types of compost at the end of the 3rd and 4th months of composting shows a decrease in the E4/E6 ratio (465 nm/665 nm), Q2/Q6 (280 nm/664 nm) and Q4/Q6 (472 nm/664 nm) for two types of composts characteristic of increasing humification of organic matter. The data from the various elementary analyzes and particularly from UV-Visible spectroscopy show that composts N°1 and N°2 can be considered ripe after 3 months of composting. But the values of the various elementary analyzes clearly show that compost N° 3 is not yet ripe. UV-Visible spectroscopy is a relatively effective method for evaluating the maturity of compost.
Abstract: Composting is a method of recovery of household solid waste. But to be useful to agriculture the compost resulting from this process must be mature. The objective of this study is to evaluate the maturity of three types of composts produced on the garbage composting unit of the NGO ENPRO in Lomé. Three types of compost (garbage, fruit waste, animal...
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