Calculated Absorption Values Research Articles

Comparative Study of the Optoelectronic, Reactivity Descriptors, and Thermodynamic Properties for Derivatives of Fluorene, and its Hetero-Analogous (Si, NH, O, S, and Se) by Employing the DFT and TD-DFT Approaches

A comparative study of the optoelectronic, reactivity descriptors, and thermodynamic properties for derivatives of fluorene, and its hetero - analogous (Si, NH, O, S, and Se) was performed by employing the DFT and TD-DFT approaches in the gaseous state. Based on the DFT approach, the thermodynamic properties and molecular electrostatic potential were computed while based on the TD-DFT approach, optoelectronic properties were calculated by employing the B3LYP/6-311(d,p) level. The reactivity descriptors were calculated by using an electronic property (HOMO and LUMO energies). The calculated absorption values of investigated compounds are predicted to range from 330-643nm. Comparatively, all the investigated compounds are expected used in the field of designing new types of optoelectronic materials.

Density functional theory studies on molecular structure, vibrational spectra, AIM, HOMO-LUMO, electronic properties, and NBO analysis of benzoic acid monomer and dimer

In this study, the molecular structure, vibrational frequencies, and atom-in-molecule (AIM) analysis of the benzoic acid monomer and dimer were investigated. Geometry optimization and vibrational frequency calculations for the monomer and dimer were carried out at the density functional theory (DFT) level with the 6-311++G(2d,p) basis set. UV-Vis spectroscopy and electronic properties (i.e., excitation energies, oscillator strengths) were calculated by time-dependent DFT (TD-DFT) in different solvents. The calculated absorption values mainly represented excitation from HOMO-1 (H-1)  LUMO and HOMO  LUMO+2 (L+2). The structure-activity relationship was interpreted by its molecular electrostatic potential (MEP) surface, which is very useful to the research of molecular structures and their physiochemical-property relationships. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy was analysed. The HOMO-LUMO energy gap and other related molecular properties were also calculated. In addition, natural bond orbital (NBO) analysis was carried out to investigate the various intra-intermolecular interactions in the molecular system.

Epigenetically modified nucleobases (5hmc, 5fc, and 5caC) interaction with boron and nitrogen doped porous graphene (B/N-pGr) as promising materials for biosensing application: A density functional theory calculations

In this present work, porous graphene (pGr), boron (B-pGr), and nitrogen (N-pGr) doped porous sheets are explored as a bio-sensor device for sensing modified nucleobases (MBs) in cancer therapy using density functional theory (DFT). The obtained geometrical, energetic and electronic properties revealed that the B-pGr is highly reactive and it adsorbs MBs better than the pGr and N-pGr, because B atom holds empty p-orbitals which easily interact with partially filled p-orbital of N and O atom. Thus, the adsorption energies of 5hmc, 5caC, and 5fc on B-pGr are high rather than the pGr and N-pGr. The corresponding adsorption energies are −96.074, −77.0, and −60.721 kcal/mol for 5hmc, 5caC, and 5fc respectively. The positive signature of ΔN values (0.005 eV, 0.076 eV, and 0.047 in MBs on pGr and 0.171 eV, 0.252 eV and 0.205 eV in MBs on N-pGr) are obtained at MBs on pGr and N-pGr complex. The negative ΔN values (−0.141 eV, −0.032 eV, and −0.061 eV in MBs on B-pGr) are obtained at MBs of B-pGr. The calculated absorption values shows that the B-pGr is strongly adsorbed MBs at 342 nm. The obtained results exhibit that the B-pGr sheet retains significant therapeutic potential as a bio-sensing application for cancer therapy.

Reversed photochromism reactivity of malononitrile attached bisthienylthene

ABSTRACTAn electron acceptor, malononitrile, was attached to bisthienylethene derivative. The significant influence of electron nature result a reversed phtochromism. Investigation of MT in THF demonstrates the reversible ring-open and ring-close. Upon irradiation of 405 nm laser, the solution color changed from yellowish to colorless, which is different from most of the photochromic colored phenomenon. Upon 254 nm irradiation, the original yellowish state can be recovered. Due to the attachment of malononitrile, the photo-/thermal-stability were enhanced. The ring-open/ring-closed forms were optimized by Dmol3. The distance between photocyclizing atoms in aptiparallel conformation meets the requirement for photochromic reaction. And the calculated absorption values were also in agreement with the experimental ones.

Evaluation of optical coherence quantitation of analytes in turbid media by use of two wavelengths

We introduce a novel method for determining analyte concentration as a function of depth in a highly scattering media by use of a dual-wavelength optical coherence tomography system. We account for the effect of scattering on the measured attenuation by using a second wavelength that is not absorbed by the sample. We assess the applicability of this technique by measuring the concentration of water in an Intralipid phantom, using a probe wavelength of 1.53 microm and a reference wavelength of 1.31 microm. The results of our study show a strong correlation between the measured absorption and the water content of the sample. The accuracy of the technique, however, was limited by the dominance of scattering over absorption in the turbid media. Thus, although the effects of scattering were minimized, significant errors remained in the calculated absorption values. More-accurate results could be obtained with the use of more powerful superluminescent diodes and a choice of wavelengths at which absorption effects are more significant relative to scattering.

Nitrogen Absorption and Endogenous Nitrogen along the Intestinal Tract of Chicks

Six groups of 15 chicks each were fed ad libitum experimental diets that contained between 0.4 and 35 g nitrogen/kg, from 10 to 16 d of age. Soybean meal was the only source of protein, and the marker was magnesium ferrite. The calculated absorption values obtained by regression analysis were higher than the determined apparent values, mainly in the duodenum and upper jejunum, due to elimination of endogenous nitrogen secretion. At the lower ileum, the calculated and the measured (apparent) absorption values were almost identical; thus, with soybean as the protein source in a diet containing a normal level of protein (18–35 N/kg diet), there is no need for endogenous nitrogen correction. Absorption of the endogenous nitrogen in chicks fed ad libitum a nitrogen-free diet was almost completed at the lower ileum (95%).

Vertical incidence absorption calculated using electron density profiles from rocket experiments and comparison with observations during the winter anomaly

In the first part of this paper ground-based measurements of vertical incidence absorption are compared with values calculated from electron density profiles from simultaneous rocket experiments. These data were obtained at Wallops Island during an investigation of the winter anomaly in radiowave absorption. The measurements were made at 3.03 MHz during five of the rocket flights and at 1.8 MHz on four others. Satisfactory agreement between observed and calculated values of absorption is obtained for an electron collision frequency model v m = 6.3 × 10 5 p where p is the pressure (in N m −2) from CIRA 1972. In the second part of the paper this electron collision frequency model is used in the calculation of vertical incidence absorption as a function of frequency between 1.7 and 3.0 MHz. The nine electron density profiles from the winter season are used together with five additional profiles from rocket flights in other seasons, all profiles being for a solar zenith angle of about 60°. Examination of the calculated values shows that the absorption is more sensitive to frequency changes than expected particularly for winter days, even at frequencies much less than ƒoE. The occurrence and number of multiple echoes in the ionograms is consistent with the calculated absorption values.

Sound absorption measurements at 10–60 kHz in near-freezing sea water

Sound propagation measurements at various frequencies between 10 and 60 kHz were made in April 1974 under the pack ice near Pt. Barrow, Alaska. With a stationary transmitter at mid-depth, a series of sound level versus depth profiles at ranges between 40 and 1300 m were obtained and used to calculate the absorption coefficient. Although the sound speed profile contained many small irregularities which caused undesirable fluctuations, it had no large features that would change the average intensity at the ranges and depths at which the sound was received. The average temperature and salinity were −1.6 °C and 32.3 0/00, respectively. The calculated absorption values in decibels per kiloyard were 2.5±0.5 at 10 kHz, 4.5±0.5 at 20 kHz, 8.3±0.5 at 30 kHz, 10.7±0.4 at 40 kHz, and 13.9±0.5 at 60 kHz. These values indicate a relaxation frequency, assumed due to MgSO4, of 27±5 kHz, a value much lower than that predicted by the Schulkin–Marsh equation, but about the same as that determined by Greene in similar low-temperature water. Subject Classification: 30.20, 30.80; 35.24.

Atmospheric Absorption Values from Aircraft Flyover Noise Signals

Experimental values of sound absorption were obtained from noise signals recorded at five ground positions during a series of 20 flyovers by two aircraft during a single day of field measurements. Differences in 13-oct band noise levels observed at the ground positions for the same angle of radiation from the aircraft were used to determine absorption values which are compared to calculated values of sound absorption based upon both surface and altitude measurements of temperature and humidity. The analysis did not assume uniformity of the sound source from flight to flight nor uniformity of sound power output or directivity characteristics for flights made at different altitudes. Experimental atomspheric absorption values based upon combined data for all flyovers showed good agreement (±0.8 dB per 1000 ft) with calculated absorption values for frequencies from 1250 to 6300 Hz. For the frequency range from 400 to 1000 Hz, experimental values (typically 2 dB per thousand feet) were significantly greater than calculated values. [Work supported by NASA.]

Ruby laser transmission and the lens.

The earliest recorded study of the transmission of light by the ocular *media is attributed to Aschkinass (1895), but according to Meyer-Schwickerath (I960) his method was grossly inaccurate. Luckiesh (I92 I) calculated the transmissivity of the ocular media on the basis that it equalled that of a layer of water 2-28 cm. thick. Shoji (1923) and Bucklers (I926) both made measurements of transmission but the wavelengths used were all below 400 m,u. In a classic paper, Ludvigh and McCarthy (I938) estimated the transmission of light of wavelengths from 400 to 820 mg to be 50 per cent. This paper is much quoted in the subsequent literature, and Davson (I963) quotes only the figure of 50 per cent. In fact Ludvigh and McCarthy based their estimate on experiments on only four eyes, all of which had been enucleated because they contained malignant melanomas. It can be reasonably argued that the ocular media may well have undergone pathological change while remaining clear to the naked eye. The results of Ludvigh and McCarthy (1938) appear to have been accepted until 1951, when they were seriously questioned by Wald (I 95 I). At that time Meyer-Schwickerath (I95I), in developing his light-coagulator, became interested in the transmission of light by the ocular media; he repeated the experiments of Ludvigh and McCarthy (I938) and arrived at the same value of 50 per cent. However, he had no hesitation in discarding the results because the specimens used showed signs of post mortem change when examined critically. Weale (I953), discussing the nature of light reaching the retinal elements after its passage through the ocular media, stated that far as the human eye is concerned, such knowledge is very inadequate in the case of the enucleated eye and non-existent in that of the eye in situ. Meyer-Schwickerath (I954) carried out further studies and calculated absorption values on the assumption that they were the same as that of 2 28 cm. water, quoting Goldmann, Konig, and Mader (I950) to justify this assumption. Such calculations showed that, at a wavelength of 694-3 mg, transmission via the ocular media was about 95 per cent. Wiesinger, Schmidt, Williams, Tiller, Ruffin, Guerry, and Ham (1956) studied the transmission of light via the ocular media of nine freshly-enucleated rabbit eyes, using a spectrophotometer operating from 380 to I,400 mg±. Their results also showed that, in the 694-3 mg range, transmission is of the order of 95 per cent. The technique appears to be free of major sources of error but, again, all the ocular media were grouped together in this study. There seems to be no work recorded in the literature in which the transmission of non-coherent light through the individual ocular media has been measured. Ham, Williams, Geeraets, Ruffin, and Mueller (I963) and Geeraets and Berry (I968) confirmed the figure of 95 per cent., again using non-coherent light. It may be concluded that the