scholarly journals Asymmetric Supercapacitors: Optical and Thermal Effects When Active Carbon Electrodes Are Embedded with Nano-Scale Semiconductor Dots

2021 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Haim Grebel
Keyword(s):  
Experimental Data ◽  
Active Carbon ◽  
Thermal Effects ◽  
Ir Absorption ◽  
High Concentration ◽  
Absorption Bands ◽  
Asymmetric Supercapacitors ◽  
Light Spectra ◽  
Thermal Capacitance ◽  
Optically Induced

Optical and thermal effects in asymmetric supercapacitors, whose active-carbon (AC) electrodes were embedded with nano-Si (n-Si) quantum dots (QD), are reported. We describe two structures: (1) p-n-like, obtained by using a polyethylimine (PEI) binder for the “n” electrode and a polyvinylpyrrolidone (PVP) binder for the “p” electrode; (2) a single component binder—poly(methyl methacrylate) (PMMA). In general, AC appears black to the naked eye and one may assume that it indiscriminately absorbs all light spectra. However, on top of a flat lossy spectrum, AC (from two manufacturers) exhibited two distinct absorption bands: one in the blue (~400 nm) and the other one in the near IR (~840 nm). The n-Si material accentuated the absorption in the blue and bleached the IR absorption. Both bands contributed to capacitance increase: (a) when using aqueous solution and a PMMA binder, the optical-related increased capacitance was 20% for low n-Si concentration and more than 100% for a high-concentration dose; (b) when using ion liquid (IL) electrolyte, the large, thermal capacitance increase (of ca. 40%) was comparable to the optical effect (of ca. 42%) and hence was assigned as an optically induced thermal effect. The experimental data point to an optically induced capacitance increase even in the absence of the n-Si dots. Overall, the experimental data suggest intriguing possibilities for optically controlled supercapacitors.

Nevirapine Pharmaceutical Cocrystal: Design, Development and Formulation

2019 ◽  
Vol 9 (3) ◽  
pp. 240-247
Author(s):  
Prabhakar Panzade ◽  
Priyanka Somani ◽  
Pavan Rathi
Keyword(s):  
Dosage Form ◽  
In Vitro Dissolution ◽  
Soluble Form ◽  
Ir Absorption ◽  
Stoichiometric Ratio ◽  
Design Development ◽  
Formulation Development ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Pharmaceutical Cocrystal

Background and Objective: The top approach to deliver poorly soluble drugs is the use of a highly soluble form. The present study was conducted to enhance the solubility and dissolution of a poorly aqueous soluble drug nevirapine via a pharmaceutical cocrystal. Another objective of the study was to check the potential of the nevirapine cocrystal in the dosage form. Methods: A neat and liquid assisted grinding method was employed to prepare nevirapine cocrystals in a 1:1 and 1:2 stoichiometric ratio of drug:coformer by screening various coformers. The prepared cocrystals were preliminary investigated for melting point and saturation solubility. The selected cocrystal was further confirmed by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), and Xray Powder Diffraction (XRPD). Further, the cocrystal was subjected to in vitro dissolution study and formulation development. Results: The cocrystal of Nevirapine (NVP) with Para-Amino Benzoic Acid (PABA) coformer prepared by neat grinding in 1:2 ratio exhibited greater solubility. The shifts in IR absorption bands, alterations in DSC thermogram, and distinct XRPD pattern showed the formation of the NVP-PABA cocrystal. Dissolution of NVP-PABA cocrystal enhanced by 38% in 0.1N HCl. Immediate release tablets of NVP-PABA cocrystal exhibited better drug release and less disintegration time. Conclusion: A remarkable increase in the solubility and dissolution of NVP was obtained through the cocrystal with PABA. The cocrystal also showed great potential in the dosage form which may provide future direction for other drugs.

Formation and bleaching of optically-induced absorption bands in CdS:Cd, Cu crystals

1978 ◽  
Vol 39 (2) ◽  
pp. 185-190 ◽  
Author(s):  
S. Kanev ◽  
K. Tsvetkova ◽  
M. Georgiev ◽  
K. Kochev ◽  
T. Todorov
Keyword(s):  
Absorption Bands ◽  
Induced Absorption ◽  
Optically Induced

Composition, particle size, and near-infrared irradiation effects on optical properties of Au–Au2S nanoparticles

2008 ◽  
Vol 23 (1) ◽  
pp. 281-293 ◽  
Author(s):  
Mei Chee Tan ◽  
Jackie Y. Ying ◽  
Gan Moog Chow
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Thermal Effects ◽  
Near Infrared ◽  
Sodium Sulfide ◽  
Irradiation Effects ◽  
Absorption Bands ◽  
Molar Ratios ◽  
Nir Absorption ◽  
Structure And Microstructure

Near-infrared (NIR)-absorbing nanoparticles synthesized by the reduction of tetrachloroauric acid (HAuCl4) using sodium sulfide (Na2S) exhibited absorption bands at ∼530 nm and at the NIR region of 650−1100 nm. A detailed study on the structure and microstructure of as-synthesized nanoparticles was reported previously. The as-synthesized nanoparticles were found to consist of amorphous AuxS (x = ∼2), mostly well mixed within crystalline Au. In this work, the optical properties were tailored by varying the precursor molar ratios of HAuCl4 and Na2S. In addition, a detailed study of composition and particle-size effects on the optical properties was discussed. The change of polarizability by the introduction of S in the form of AuxS (x = ∼2) had a significant effect on NIR absorption. Also, it was found in this work that exposure of these particles to NIR irradiation using a Nd:YAG laser resulted in loss of the NIR absorption band. Thermal effects generated during NIR irradiation had led to microstructural changes that modified the optical properties of particles.

Application of biological activated carbon anaerobic reactor for treatment of hazardous chemicals

2006 ◽  
Vol 53 (11) ◽  
pp. 251-260 ◽  
Author(s):  
H. Tsuno ◽  
M. Kawamura ◽  
T. Oya
Keyword(s):  
Experimental Data ◽  
Activated Carbon ◽  
Organic Compounds ◽  
Adsorptive Capacity ◽  
Biological Degradation ◽  
Hazardous Chemicals ◽  
High Concentration ◽  
Expanded Bed ◽  
Biological Activated Carbon ◽  
Anaerobic Reactor

An expanded-bed anaerobic reactor with granular activated carbon (GAC) medium has been developed to treat wastewaters that contain a high concentration of inhibitory and/or refractory organic compounds as well as readily degradable organic compounds. The process is characterised by a combination of two removal mechanisms; adsorption on GAC and biological degradation by microorganisms grown on GAC. Applicability of the reactor to treatment of phenol, chloroacetaldehyde (CAA), pentachlorophenol (PCP) and tetrachloroethylene (PCE) was discussed based on experimental data. All chemicals focused on here were removed well and stably at a removal efficiency of more than 98% even during starting operation and shock load operation. Chemicals in influent that exceeded biological degradation capacity was initially adsorbed on GAC and then gradually degraded, and hence the adsorptive capacity of GAC was regenerated biologically. These results proved that a biological activated carbon anaerobic reactor was effective for treatment of wastewater containing hazardous chemicals, especially for strongly absorbable chemicals, as well as readily degradable organic compounds at high concentration.

The Influence of Slit-Width on the Shape and Intensity of Infra-Red Absorption Bands

1951 ◽  
Vol 4 (2) ◽  
pp. 172
Author(s):  
JB Willis
Keyword(s):  
Experimental Data ◽  
Half Width ◽  
Slit Width ◽  
Absorption Bands ◽  
Infra Red ◽  
Spectrometer Slit

Making certain assumptions as to the shape of infra-red absorption bands and the shape of the slit function of the monochromator, expressions are obtained for the dependence on spectrometer slit-width of the intensity and half-width of absorption bands. Experimental data to confirm the accuracy of these deductions are presented.

scholarly journals Изотопные эффекты в спектрах комплексов с водородными связями. Ангармонические расчеты изотопологов комплекса [F(HF)-=SUB=-2-=/SUB=-]-=SUP=---=/SUP=-

2020 ◽  
Vol 128 (8) ◽  
pp. 1077
Author(s):  
В.П. Булычев ◽  
М.В. Бутурлимова ◽  
К.Г. Тохадзе
Keyword(s):  
Basis Set ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Spectral Parameters ◽  
Basis Set Superposition Error ◽  
Band Frequency ◽  
Normal Vibrations ◽  
K Meson ◽  
Anharmonic Interactions ◽  
Good Agreement

The frequencies and intensities of IR absorption bands of symmetric and asymmetric H-bonded complexes [FL1FL2F]- (L1, L2 = K-meson Ka, proton H, deuton D, and triton T) are calculated. The equilibrium configuration and potential energy and dipole moment surfaces of isotopologues [FL1FL2F]- were calculated by the MP2/6-311++G(3df,3pd) method with the basis set superposition error taken into account. The calculations of spectral parameters with allowance for anharmonic interactions of all vibrations were carried out using the second-order vibrational perturbation theory. Variation of Li and L2 masses in wide regions allowed significant changes in the forms of normal vibrations and values of anharmonic interaction constants upon isotopic substitution to be obtained. The trends in the changes of spectral parameters were determined upon transition from one symmetric isotopologue to another and upon transition from symmetric to asymmetric isotopologues. The D-F stretching band frequency predicted for [FHFDF]- is in good agreement with the experimental value. The assignment of this band was improved.

scholarly journals Local vibrational modes of vacancy-oxygen-related complexes at room temperature

2020 ◽  
Vol 56 (4) ◽  
pp. 480-487
Author(s):  
E. A. Tolkacheva ◽  
V. P. Markevich ◽  
L. I. Murin
Keyword(s):  
Absorption Band ◽  
Room Temperature ◽  
Clear Correlation ◽  
Ir Absorption ◽  
Oxygen Impurity ◽  
Interstitial Oxygen ◽  
Vibrational Modes ◽  
Oxygen Defect ◽  
Absorption Bands ◽  
Local Vibrational Modes

The isotopic content of natural silicon (28Si (92.23 %), 29Si (4.68 %) и 30Si (3.09 %)) affects noticeably the shape of IR absorption bands related to the oxygen impurity atoms. In the present work an attempt is undertaken to determine the positions of local vibrational modes (LVMs), related to quasimolecules 28Si16OS29Si and 28Si16OS30Si (OS – substitutional oxygen atom), for the absorption spectra measured at room temperature. An estimation of the isotopic shifts of corresponding modes is done by fitting the shape of the experimentally measured absorption band related to the vacancy–oxygen center in irradiated Si crystals. The LVM isotope shifts are found to be equal 2,2 ± 0.25 cm–1 for 28Si-16OS29Si and 4,3 ± 0,9 см–1 for 28Si-16OS30Si in relation to the basic band due to 28Si-16OS28Si, and the full width at half maximum of the A-center absorption band (28Si-16OS28Si) is 5,3 ± 0.25 cm–1. By means of infrared absorption spectroscopy a clear correlation between the disappearance of the divacancy (V2) in the temperature range 200–275 ºС and appearance of two absorption bands with their maxima at 825.8 and 839.2 cm–1 in irradiated oxygen-rich Si crystals is found. The band positioned at 825.8 cm–1 is assigned to a divacancy-oxygen defect V2O formed via an interaction of mobile V2 with interstitial oxygen (Oi ) atoms. The 839.2 cm–1 band is much more pronounced in neutron irradiated samples as compared to samples irradiated with electrons. We argue that it is related to a trivacancy–oxygen defect (V3O) formed via an interaction of mobile V3 with Oi atoms.

Magneto-Chemical Properties of Some New Ni and Co Rare-Earth Metal Tungstates

2007 ◽  
Vol 128 ◽  
pp. 207-212 ◽  
Author(s):  
Adam Worsztynowicz ◽  
Slawomir M. Kaczmarek ◽  
Elzbieta Tomaszewicz
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Epr Spectroscopy ◽  
Chemical Properties ◽  
Earth Metal ◽  
Temperature Evolution ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Metal Tungstates

New d-electron and rare-earth metal tungstates (CoRE2W2O10; CoRE4W3O16; Co2RE2W3O14 and NiRE2W2O10) were studied by the IR and EPR spectroscopy methods. The IR absorption bands with their maxima can be assigned to the symmetric and asymmetric stretching modes of W-O bonds in the joint of WO6 octahedra and also to the oxygen double WOOW bridge bonds. The wide, unstructured EPR powder spectra of these compounds and their temperature evolution have been analyzed and interpreted.

Method for determining the formation constants of intermolecular H-bonding from IR spectroscopy data

2021 ◽  
pp. 55-58
Author(s):  
N.U. Mulloev ◽  
◽  
N.L. Lavrik ◽  
J.O. Yusypova ◽  
N.A. Majidov ◽  
...  
Keyword(s):  
Optical Density ◽  
Formation Constants ◽  
Butyl Alcohol ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Ir Absorption ◽  
Visible Spectroscopy ◽  
Absorption Bands ◽  
Intermolecular Hydrogen Bonds ◽  
Uv Visible

An experimental method is proposed for determining the efficiency of the formation of intermolecular hydrogen bonds by determining the formation constant of the H-complex (K). The essence of the experiment to determine the value of K is that for one initial concentration of the proton donor, it is necessary to register the change in the optical density at the absorption wavelength of the monomers and the change in the optical density of the complexes of IR absorption bands at two concentrations of the proton acceptor. This approach was tested on the example of the interaction of butyl alcohol (proton donor) with 4-chloromethyl-1.3-dioxolane (proton acceptor). The obtained value of the equilibrium constant was 72.2 M-1. It is concluded that the proposed method for determining the value of K can be used not only in IR, but also in UV-visible spectroscopy.

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