scholarly journals Surface Functionality Features of Porous Silicon Prepared and Treated in Different Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yu. M. Spivak ◽  
S. V. Mjakin ◽  
V. A. Moshnikov ◽  
M. F. Panov ◽  
A. O. Belorus ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Ir Spectroscopy ◽  
Ir Spectra ◽  
Current Density ◽  
Functional Composition ◽  
Acid Base ◽  
Oh Groups ◽  
Surface Functionality ◽  
Lewis Acidic Sites ◽  
Acidic Sites

Hydrophilic layers of porous silicon are prepared by single- or two-step anodization and characterized by evaluating their surface hydrophilicity and contents of functional groups using IR spectroscopy and adsorption of acid-base indicators with differentpKavalues. The surface functional composition of the synthesized samples is shown to be adjustable depending on the anodization current density. The surface of samples obtained at anodization current density 30 mA/cm2is predominantly occupied withpKa2.5 corresponding to ≡Si–OH groups. The increase of current density to 80 mA/cm2results in the increase of surface functional nonuniformity with the formation of versatile centers, primarily Lewis acidic sites corresponding to Si atoms, as indicated by selective indicator adsorption in agreement with the disappearance of Si–H bonds in IR spectra and overall surface disordering according to SEM and AFM data.

Acid-base properties of modified aluminas

1982 ◽  
Vol 47 (8) ◽  
pp. 2044-2060 ◽  
Author(s):  
E. A. Paukshtis ◽  
P. I. Soltanov ◽  
E. N. Yurchenko ◽  
Květa Jirátová
Keyword(s):  
Carbon Monoxide ◽  
Ir Spectroscopy ◽  
Relative Proportion ◽  
Total Acidity ◽  
Acid Base ◽  
Pure Alumina ◽  
Oh Groups ◽  
Concentration Of Ions ◽  
Ir Spectroscopic ◽  
Base Properties

Acid-base properties of the pure alumina and aluminas modified by addition of various ions were determined by IR spectroscopic and Benesi method. The quality and concentration of OH groups of alumina samples containing SO42-, F-, Cl-, Na+, Zn2+ and Mg2+ ions were determined by IR spectroscopy, Pyridine, benzonitrile and carbon monoxide were used to determine the concentration and strength of aprotic centres and deuteriochloroform was used to determine the concentration and strength of basic centres. The results allowed to evaluate changes in the above properties caused by changes in the concentration of ions in alumina. It was found that the total acidity of modified aluminas determined by Benesi method correlates well with the relative proportion of acidic OH groups in the total spectrum of OH groups.

Basic properties of anodized porous silicon formed under uniform current density

1994 ◽  
Vol 77 (4) ◽  
pp. 97-105
Author(s):  
Hidekazu Aoyagi ◽  
Akira Motohashi ◽  
Akira Kinoshita ◽  
Tomoyoshi Aono ◽  
Akinobu Satoh
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Basic Properties ◽  
Uniform Current

Structural, Surface Morphological and Photoluminescence Properties of Nanostructured Porous Silicon Material for Optoelectronics Application

2012 ◽  
Vol 584 ◽  
pp. 290-294 ◽  
Author(s):  
Jeyaprakash Pandiarajan ◽  
Natarajan Jeyakumaran ◽  
Natarajan Prithivikumaran
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Light Emitting Diode ◽  
Radiative Transition ◽  
Sem Images ◽  
Optoelectronic Application ◽  
Gap Opening ◽  
P Type

The promotion of silicon (Si) from being the key material for microelectronics to an interesting material for optoelectronic application is a consequence of the possibility to reduce its device dimensionally by a cheap and easy technique. In fact, electrochemical etching of Si under controlled conditions leads to the formation of nanocrystalline porous silicon (PS) where quantum confinement of photo excited carriers and surface species yield to a band gap opening and an increased radiative transition rate resulting in efficient light emission. In the present study, the nanostructured PS samples were prepared using anodic etching of p-type silicon. The effect of current density on structural and optical properties of PS, has been investigated. XRD studies confirm the presence of silicon nanocrystallites in the PS structure. By increasing the current density, the average estimated values of grain size are found to be decreased. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. The observed PL spectra at room temperature for all the current densities confirm the formation of PS structures with nanocrystalline features. PL studies reveal that there is a prominent visible emission peak at 606 nm. The obtained variation of intensity in PL emission may be used for intensity varied light emitting diode applications. These studies confirm that the PS is a versatile material with potential for optoelectronics application.

scholarly journals Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 829 ◽  
Author(s):  
Zhang ◽  
Yuan ◽  
Miao ◽  
Li ◽  
Shan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Performance ◽  
High Yield ◽  
Side Chain ◽  
Impregnation Method ◽  
Basic Sites ◽  
Lewis Acidic Sites ◽  
X Zeolite ◽  
Acidic Sites ◽  
Negative Effect

The side-chain alkylation of toluene with methanol was investigated over some Fe-modified Cs ion-exchanged X zeolite (CsX) catalysts prepared via the impregnation method using different iron sources. The absorption/activation behaviors of the reactants on the surface of the catalysts were studied by in situ Fourier-transform infrared (FT-IR) spectroscopy and temperature programmed desorption (TPD) mass measurements. Modification of CsX with a small amount of FeCl3 could result in a considerable decrease in catalytic activity, due mainly to the remarkable decrease in the density of acidic and basic sites of the catalysts. Interestingly, the Fe(NO3)3-modified CsX with an optimum Fe loading of 0.15 wt.% shows improved catalytic activity and high yield compared to the side-chain alkylation products. Modification of CsX with Fe(NO3)3 could also result in a decrease in basic sites of the catalyst. However, such a change does not bring an obvious negative effect on the adsorption/activation of toluene, while it could effectively inhibit the generation of the undesired bidentate formate. Furthermore, the introduced FeOx species (derived from the decomposition of Fe(NO3)3) may also act as new Lewis acidic sites to participate in the activation of methanol and to stabilize the formed active intermediates (i.e., unidentate formate). Therefore, modification of CsX with a suitable amount of Fe(NO3)3 may adjust its adsorption/activation ability for reagents by changing the acid–base properties of the catalyst, which can finally enhance the catalytic performance for the side-chain alkylation of toluene with methanol.

scholarly journals Evaluation of solubility and histological effect of 11-keto-β-Boswellic acid on the diabetic mice liver using FTIR-PCA analysis and microscopy

2021 ◽  
Author(s):  
I.S. Al-Amri ◽  
F. Mabood ◽  
I.T. Kadim ◽  
A.Y. Alkindi ◽  
A. Al-Harrasi ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Ir Spectra ◽  
Liver Tissue ◽  
Diabetic Control ◽  
Control Group ◽  
Diabetic Mice ◽  
Boswellic Acid ◽  
Ft Ir ◽  
Mice Liver ◽  
Ft Ir Spectroscopy

ABSTRACTThis study was designed to develop a rapid, sensitive, accurate, and inexpensive Fourier Transform Infrared Reflectance (FT-IR) Spectroscopy coupled with Principle Component Analysis (PCA) as a detection technique to evaluate the solubility of 11-Keto-β-Boswellic acid (KBA), from the gum resin extracted from the Omani frankincense, (Boswellia sacra) in the liver of STZ induced diabetic mice. This study also investigated the effect of KBA on the histological changes of hepatocytes of diabetic mice. Liver tissue samples from three groups of mice included normal control group, diabetic control group and diabetic group treated IP with KBA were scanned with FT-IR spectrophotometer in the reflection mode. FT-IR Spectra were collected in the wavenumber range from 400 to 4000cm-1 using ATR accessorry. The results of FT-IR Spectra were analyzed by using multivariate method Principle Component Analysis. The PCA score plot is an exploratory multivariate method indicated that there was a complete segregation among the three groups of liver samples based on change in variation of position of wavenumber in FT-IR spectra, which revealed that there is a clear effect of KBA solubility on treatments. The histological features showed an improvement in the liver tissues with normal structures of hepatocytes with exhibiting mild vacuolations in their cytoplasm. In conclusion, reflectance FT-IR spectroscopy coupled with PCA could be deployed as a new detection method for rapid, low cost and non-destructive method for evaluating of treatment effects in diseased liver tissue based on the solubility of KBA. Histological findings demonstrated the protective effective of KBA on improving the morphology of liver tissue in diabetic mice which resulted in complete recovery to the damage observed in diabetic control group.Summary StatementReflectance FT-IR spectroscopy coupled with PCA has been deployed as a new rapid, inexpensive and non-destructive detection method to examine the solubility of 11-keto-β-Boswellic acid (KBA) in streptozotocin (STZ) induced-diabetes mice liver tissue following intraperitoneal treatment. Moreover, microscopic study of liver tissue histopathology revealed that KBA has a protecting effect against STZ damage.

scholarly journals The Bio-fabrication of Gold Nanoparticles (AuNPs) by Green Method and Study of its Electrochemical Applications

2020 ◽  
Vol 1 (4) ◽  
pp. 22-25
Author(s):  
Azwan Morni
Keyword(s):  
Gold Nanoparticles ◽  
Ir Spectroscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Green Method ◽  
Oh Groups ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

This study reports a green method for the synthesis of gold nanoparticles (AuNPs) using the aqueous extract of Salix aegyptiaca extract. The effects of gold salt concentration, extract concentration and extract quantity were investigated on nanoparticles synthesis. Novel methods of ideally synthesizing AuNPs are thus thought that are formed at ambient temperatures, neutral pH, low costs and environmentally friendly fashion. AuNPs were characterized with different techniques such as UV–vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, and TEM. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary carbonyl group, -OH groups and other stabilizing functional groups. TEM experiments showed that these nanoparticles are formed with various shapes and X-ray diffraction pattern showed high purity and face centered cubic structure of AuNPs. For electrochemical properties of AuNPs, a modified glassy carbon electrode using AuNPs (AuNPs/GCE) was investigated. The results show that electronic transmission rate between the modified electrode and [Fe (CN)6]3-/4- increased.

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