Absorption Max Research Articles

High energy laser & systems to neutralise stellar coronal mass ejections (CME) plasma

With CME plasma and shockwave travelling at 600+ km/sec, active methods such as high energy electron lasers (HEL) and mirrors are effective at making contact with ionised atoms in CME. Electrons pulsed from kW to MW laser(s) could polarise ionised atoms such as Fe16+, O7/8+, Mg, He2+,etc to fill valence pairs. As high-FIP atoms are electromagnetically trapped with a higher susceptibility from lower e- density and temperatures, CME plasma clouds can be neutralised, separated, and reduced in velocity trajectory around planet. Study outlines interactions between Electron Laser and CME plasma cloud, orbital geometry, build of high energy lasers, subsystems, as well as recoils, and cloud charge dynamics with e- interactions to neutralise CME particles. Additional space-based systems are designed such as mirrors in closer orbit to align lower velocity light beams. In approaching higher electron recombination and FIP ionisation of laser-plasma ion cluster density, max absorption of e- to CME could be approached with similar beam, CME, mirror angles and alignment, where e- couple and fill valence shells. Models evaluate efficacy of coherent laser beams of charged electrons, X-rays, infrared (IR), and/or electron/radio Hz to polarize CME column charge densities, with optimal CME scatter geometry and time window. Low cost ground experiments are discussed. Models suggest every ~1 km gap laser creates when CME t=8.255min creates a 10,067 km gap for Earth to orbit through. Such a HEL laser, reflecting mirrors, and space systems could neutralize plasma CME Cloud within 92.818M mi (Sun-Earth distance) and mitigate effects and trillion dollar costs from Carrington-type CME flares, and supernovae.

Understanding prominent effects of the intramolecular hydrogen bond on the photophysical properties and antiradical abilities of six flavonoids

The photophysical properties and antiradical abilities of 5-Hydroxyflavone, 3,5-Dihydroxyflavone, galangin, kaempferol, quercetin, and myricetin are explored using density functional theory and time-dependent density functional theory methods. The absorption spectra of the six flavonoids span the entire ultraviolet region, and their fluorescence peak intensities are faint, meeting the sunscreen requirements. Furthermore, their max absorption peaks are mainly affected by the hydroxyl groups in the A- and C-rings of the compounds. The hydrogen atom transfer, sequential proton loss electron transfer and single electron transfer followed by proton transfer mechanisms are used to evaluate their antiradical abilities. It can be concluded that the O4-H4 site of myricetin is the most active site to scavenge free radicals, revealing that the formation of intramolecular hydrogen bonds can significantly enhance molecular antiradical abilities. In a word, altering tactfully hydrogen group position is conducive to regulating the photophysical properties and antiradical abilities of flavonoids.

Enhancing light absorption of graphene with dual quasi bound states in the continuum resonances

Graphene is promising for next-generation optoelectronic devices owing to its unique optical and electronic properties whereas relatively weak light-matter interaction limits its performance. In this work, light can be absorbed totally by graphene with the aid of single layer all dielectric metasurface in the near infrared region. The metasurface is composed of periodically arranged amorphous Silicon nanocuboids quadrumer suspended in air which supports resonances governed by symmetry protected bound states in the continuum. Symmetry perturbation is introduced to the metasurface to induce quasi bound states in the continuum resonances by elements pair movement method in x or/and y direction. Light absorption performance of the hybrid structure can be enhanced to 50% at single-mode critical coupling state and 100% at dual-mode degenerate critical coupling state. Temporal coupled mode theory is used to analyze physical mechanism of max absorption Amax for both single mode and dual mode condition in two-port system as an analog of transparent hybrid structure. Furthermore, absorption performance can be tuned by varying the elevation between graphene and metasurface. Effects of metasurface's geometric parameters including scaling factor and thickness on absorption characteristics are also explored. Our results may provide a new route for enhancing light absorption of graphene or other 2D materials which may facilitate to design advanced modulators and photodetectors.

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

Simple two spectrophotometric methods for estimation of Cephalexin in pure and pharmaceutical dosage form

This study describes two extraction-free and direct spectrophotometric methods for the determination of Cephalexin in a pure and pharmaceutical dosage form. In this study, a zero-order method has exhibited maximum absorption max at 263 nm, while area under curve method has calculated in the range 260-266nm. The Linearity of both methods in the range (10- 60 nm), the limit of detection (LOD) is 0.808 for Zero-order method and 0.781 for the area under curve method. These methods are successfully applied to determination of Cephalexin in a pharmaceutical dosage form.

Tunable broadband, wide-angle, and polarization-dependent perfect infrared absorber based on planar structure containing phase-change material.

A multilayer absorber composed of SiO2, Fe, Ge2Sb2Te5 (GST), and Al is designed, and the absorptive properties are theoretically investigated based on the Fresnel coefficients method in the wavelength range of 300-2500nm by changing the thickness and crystallization rate of GST, the incident angle, and the polarization. The results show that the thin Fe layer plays a key role in obtaining an ultra-broadband perfect absorption. The absorption properties are polarization-dependent, and the perfect absorption can be nearly realized for a p-polarized wave at the incident angle smaller than 75° with the bandwidth larger than 316nm at 90% of max absorption value. The absorptive peak of this absorber can be tuned with the crystallization rate of GST by temperature, and the peak wavelength moves from 1433nm in the amorphous phase to 2051nm in the crystalline phase. This structure can provide a feasible route to design the tunable broadband, wide-angle, and polarization-dependent perfect absorber without lithographic patterns in the infrared band.

UV-VIS and SEM Assessment of Silver Nanoparticles Synthesized using Nd-YAG Laser as antibacterial

Introduction: Silver nanoparticle shows modern optical properties, which is observed neither in a molecule nor bulk metals. Materials and Methods: In the present study silver nanoparticles,AgNPs were produced by physics method using YAG system (Q-switched Nd-YAG laser system type HUAFEI) of a silver nitrate aqueous solution (AgNO3). The AgNPs were characterized using UV-VIS spectrometer and Scanning Electron Microscope (SEM). Results: The peak in the absorption spectra of asilver solutionwas showed an absorption max of 450 nm, which is indicated AgNPs formation. The AgNPs obtained using a laser used for the antibacterial such as S. aureus and K.pneumonia collected from Najaf city, Iraq. Conclusions: The advantages of using YAG laser in the synthesis of silver nanoparticles are environmentally friendly.

Oral Abuse Potential, Pharmacokinetics, and Safety of Once-Daily, Single-Entity, Extended-Release Hydrocodone (HYD) in Recreational Opioid Users.

Objectives. A once-daily, extended-release hydrocodone bitartrate tablet with abuse-deterrent properties (Hysingla ER [HYD]) is available for the treatment of chronic pain in appropriate patients. This study evaluated the oral abuse potential and pharmacokinetics (PK) of HYD intact, chewed, or milled to fine particles in comparison with hydrocodone solution or placebo. Design. Single-center, double-blind, randomized, five-period, five-treatment crossover study. Subjects. Healthy adult, nondependent, recreational opioid users. Methods. Forty subjects received orally administered treatments of hydrocodone 60 mg solution, HYD 60 mg intact, HYD 60 mg chewed, HYD 60 mg milled to fine particles, or placebo, separated by a five- to seven-day washout. Assessments over 36 hours postdose included subjective measures of drug liking and willingness to take drug again (assessed using visual analog scales [VAS]), pupillometry, PK, and safety measures. Results. Following oral administration, HYD intact, HYD chewed, and HYD fine particles led to significantly lower “at this moment” drug liking compared with hydrocodone solution. HYD intact and chewed were significantly different from hydrocodone solution on overall drug liking, take drug again, and good effects. Pupil constriction, as measured by pupillometry, occurred later with HYD intact and HYD chewed than with hydrocodone solution. Across treatments (hydrocodone solution, HYD fine particles, HYD chewed, and HYD intact, respectively), mean Cmax and rate of absorption (Cmax/Tmax) values decreased, respectively, and median Tmax values increased, respectively. Safety was consistent with the known effects of opioid agonists. Conclusion. HYD demonstrated reduced oral abuse potential compared with hydrocodone solution in healthy adult, nondependent, recreational opioid users.*

Simultaneous control over both molecular order and long-range alignment in films of the donor-acceptor copolymer.

Control over both molecular order and long-range alignment order in films of the donor-acceptor copolymer of 3,6-bis(thiophen-2-yl)-N,N'-bis(2-octyl-1-dodecyl)-1,4-dioxo-pyrrolo[3,4-c]pyrrole and thieno[3,2-b]thiophene (PDBT-TT) was demonstrated via off-center spin-coating (OCSC) from its blend solution with polystyrene (PS). It was found that the dichroic ratio (DR) of OCSC blend films was dependent on both the physical process of spin-coating and the effect of PS chains. The highest DR of 2.75 was obtained via OCSC from the blend solution in oDCB at 1500 rpm. Meanwhile, both the intrachain and interchain molecular order were improved in blend films compared with neat ones, which were indicated by the red-shift of the max absorption, enhanced J-aggregation absorption, and smaller π-π stacking distance (from 3.77 to 3.70 Å). According to the results of the investigation into the macro anisotropy, micro morphology, solution rheology properties, and photophysics features of films, an overall mechanism of simultaneous control over molecular and long-range order of D-A copolymer films was proposed. On the one hand, a larger viscosity and the pseudoplastic nature of the solution tuned by choosing good solvents with high boiling points and adding PS resulted in a better chain disentanglement, better shear transfer, and a slower contact line receding velocity to induce an enhanced alignment of chains and thus fibrillar aggregates. Also, the critical contact line receding velocity for alignment dominated by the solvent evaporation rate accounted for the variation of DR with OCSC rates. A vertical phase separation accompanying the formation of aligned fibrils during OCSC was also confirmed due to the friction shear between air and solution surface. On the other hand, the negligible dependence of the blend OCSC film's photophysical and morphological features on the solvent suggested the critical role of PS in determining the better intrachain conjugation in blend films, which was attributed to multiple reasons, like limited phase separation room, a coil-toward conformation promotion, and a high surface energy. Furthermore, the enhanced π-attraction and smaller steric hindrance induced by improved intrachain conjugation accounted for the smaller π-π stacking distance in the blend films than that in the neat ones.

Intestinal absorption of the antiepileptic drug substance vigabatrin is altered by infant formula in vitro and in vivo.

Vigabatrin is an antiepileptic drug substance mainly used in pediatric treatment of infantile spasms. The main source of nutrition for infants is breast milk and/or infant formula. Our hypothesis was that infant formula may affect the intestinal absorption of vigabatrin. The aim was therefore to investigate the potential effect of coadministration of infant formula with vigabatrin on the oral absorption in vitro and in vivo. The effect of vigabatrin given with an infant formula on the oral uptake and transepithelial transport was investigated in vitro in Caco-2 cells. In vivo effects of infant formula and selected amino acids on the pharmacokinetic profile of vigabatrin was investigated after oral coadministration to male Sprague–Dawley rats using acetaminophen as a marker for gastric emptying. The presence of infant formula significantly reduced the uptake rate and permeability of vigabatrin in Caco-2 cells. Oral coadministration of vigabatrin and infant formula significantly reduced Cmax and prolonged tmax of vigabatrin absorption. Ligands for the proton-coupled amino acid transporter PAT1, sarcosine, and proline/l-tryptophan had similar effects on the pharmacokinetic profile of vigabatrin. The infant formula decreased the rate of gastric emptying. Here we provide experimental evidence for an in vivo role of PAT1 in the intestinal absorption of vigabatrin. The effect of infant formula on the oral absorption of vigabatrin was found to be due to delayed gastric emptying, however, it seems reasonable that infant formula may also directly affect the intestinal absorption rate of vigabatrin possibly via PAT1.

Optimal Design of the Thickness of the Multi-Layer Absorption Plates Based on the Max Absorption Coefficient

In this paper, the thickness of the different layer of the multiple-layer homogeneous structure. is optimized designed on the condition that the absorption effort is the best Using the transfer matrix of sound pressure and particle velocity of each layer and the continuity condition at the interface between two lagers, the absorption coefficient of the multiple-layer homogeneous structure is deduced. According to the absorption coefficient, the thickness of different layer is optimized designed on the condition that the absorption effort is the best when the sound wave incident to the multiple-layer homogeneous structure with different frequency. In the last, an experiment is carried out, and the experiment results test the theoretical analysis is correct which can be applied to solve the same kind problem. Keywords: absorption coefficient multiple-layer absorption optimized design

Micromechanism of sulfurizing activated carbon and its ability to adsorb mercury

To eliminate mercury from coal-fired flue gas, sulfurization of carbons has been found to be the most inexpensive approach to solve the problem of environment contamination by mercury. This study focuses on improving the adsorption capacity of activate carbon loaded with elemental sulfur as an active phase and further use in the removal of mercury vapors from fuel gas. In this paper, equipment such as the scanning electron microscope, specific surface area test machine and fluorescence spectrophotometer are employed to study the ability of the S-loaded activated carbon. The results show that unmodified activate carbon has smooth hole surface and uneven distributed hole size. Pore walls of activate carbon modified became rougher and the hole size distribution is asymmetrical. Sulfur is uniformly distributed and is mainly bonded on the surface of the skeleton of activate carbon. In addition, a small amount of granular sulfur was loaded on the surface of the pore walls. Higher temperature creates smaller pore size and larger microporous volume. Improving the process temperature is conducive to the development of micropore and the distribution of sulfur, and a larger amount of small molecular weight sulfur are created, which is helpful in the removal of HgO through chemical adsorption. The optimum modification temperature and holding time is 550 °C and 60 min, which creates the adsorbents of the max absorption capability of 1227.5 μg Hg/g.

Acridine Red Spectrophotometric Determination of Trace IO<sub>3<sup>-</sup></sub> Based on Formation of Associated Particles

Under the conditions of HCl-KI, acridine red (AR) has a max absorption peak at 540 nm, the max absorption peak of acridine orange (AO) at 480 nm. When there is IO3-, it reacts with excessive I-to form I3-. The AR and I3-all combine to form an association particle that caused the absorption decreasing. I03-concentration in the range of 5-90×10-7mol/L can be determined by the pectrophotometry.

Chromism based on supramolecular H-bonds

Normal solvatochromic phenomena are induced by different polarities of the ground and excited states of a compound when it is dissolved in a solvent. A compound such as the perylene diimide (PDI) derivative, which has a small difference in the dipole moments of the excited and ground states, generally shows a weak color change. Herein, we found that a dilute dichloromethane (DCM) solution of the PDI derivative 1,6,7,12-tetra(4-tert-butylphenoxyl) PDI (1) with a typical concentration of 1 × 10(-5) M distinctly changed colour from red to dark blue with a distinct red-shift of both the absorption (Δλ(a)max = 32 nm) and the fluorescence (Δλ(f)max = 45 nm) when 50,000 equivalents of trifluoroacetic acid (TFA) were added. Such a new chromism originates from the stronger decrease of the energy level of the LUMO than that of the HOMO after the step-by-step H-bonding of TFA with the PDI chromophore: firstly, the imide C[double bond, length as m-dash]O functionality, then the bridged -O- and finally the TFA molecules undergo H-bonding, forming a highly polar TFA shell around the PDI molecule, as proved by the concentration variable UV-vis absorption, fluorescence, (1)H NMR, (13)C NMR, and NOE spectra, cyclic voltammetry, and quantum chemical calculations. The degree of the solution's color change (Δλ(a)max/Δλ(f)max) depends (1) on the number of the bay-substituted 4-n-butylphenoxyl groups: it amounts to 25/38 and 17/22 nm for 1,7-bis(4-tert-butylphenoxyl) PDI (2) and the bay-unsubstituted PDI 3, respectively, and (2) on the polarity of the -OH functionality: in HOOC-CX3, for example, the value of Δλ(a)max/Δλ(f)max of PDI 1 amounts to 9.5/17 nm for trichloroacetic acid (TClA, X = Cl) and 0/3.6 nm for acetic acid (AA, X = H). The protons are necessary for the chromism, and thus ethyl trifluoroacetic acid ester, EtOTFA, cannot produce any obvious red-shifting of the absorption and fluorescence for 1-3. However, 2,2,2-trifluoroethanol (TFEtOH) produces an obvious red-shift.

Effects of substituent and solvent on the UV absorption energy of 4,4′-disubstituted stilbenes

Twenty five samples of 4,4′-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4′-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter σ CC ex and polar substituent constant σ p. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4′-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (E T(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.

Optimal Design of the Thickness of the Multi-Layer Homogeneous Absorption Plates Based on the Max Absorption Coefficient of the Automotive Body

In this paper, the thickness of the different layer of the multiple-layer homogeneous structure. is optimized designed on the condition that the absorption effort is the best Using the transfer matrix of sound pressure and particle velocity of each layer and the continuity condition at the interface between two lagers, the absorption coefficient of the multiple-layer homogeneous structure is deduced. According to the absorption coefficient, the thickness of different layer is optimized designed on the condition that the absorption effort is the best when the sound wave incident to the multiple-layer homogeneous structure with different frequency. In the last, an experiment is carried out, and the experiment results test the theoretical analysis is correct which can be applied to solve the same kind problem.

Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes

A new series of pure, nanometer-sized and highly-soluble homocoupled oligodiacetylenes (HODA) consisting of two symmetrical oligodiacetylene units was synthesized with high yield and on a multi-milligram scale under mild, catalytic Sonogashira conditions. The lambda(max) and the epsilon(max) of absorption for these HODAs show an increase with the chain elongation. The lambda(max) converges to 450 nm for the longest members of the series at micromolar concentration and to 462 nm for thin drop-casted films. An additional red-shifted absorption is observed in the solid state and in solution at low temperatures, which is caused by aggregation. The lambda(max) of the fluorescence emission increases with the chain length and reaches 492 nm for the longest oligomer. The fluorescence quantum yield has its maximum for the shortest oligomer and decreases rapidly for the longer ones. A similar trend is found for the fluorescence lifetime with a maximum of 100 ps for the homocoupled monomer. The rotational correlation time shows a linear increase with the oligomer length. This reveals a significant persistence length and indicates that the HODA molecules are fully stretched molecular rods (up to 8.2 nm).

Synthesis and Optical Properties of all‐trans‐Oligodiacetylenes

A new series of pure and highly soluble oligodiacetylenes (ODAs) was synthesized in high yield and on a multi-milligram scale by a sequence of Sonogashira reactions with a strongly reduced level of homocoupling. The lambda max and epsilon max of these ODAs show an increase with both chain elongation and solvent polarity. A plot of lambda max absorption versus 1/CL (CL=conjugation length) was shown to be linear. The lambda max converges to 435 nm for the longest members of the series at micromolar concentration. This reveals that the longest wavelength absorption observed for PDA chains (lambda max up to 700 nm) is due to aggregation effects. The fluorescence quantum yield increased from monomer to trimer and decreased for longer ODAs. A similar trend is found for the lifetime of fluorescence with a maximum of 600 ps for the trimer. The observed linearity of the rotational correlation time with the oligomer length implies that the ODA chains in solution lack significant geometrical changes. This implies that the ODAs in solution are fully stretched molecular rods of up to 4 nm in length.

Application of Rat In Situ Single-pass Intestinal Perfusion in the Evaluation of Presystemic Extraction of Indinavir Under Different Perfusion Rates

First-pass effect has been an important concern for oral pharmaceuticals. An in vivo system was developed for measuring different concentrations of pharmaceuticals in the portal vein and hepatic vein (via the inferior vena cava) for delineating presystemic metabolism under different perfusion rates by using indinavir as an exemplary agent. An in situ single-pass intestinal perfusion technique was modified from previous studies to concomitantly obtain portal and hepatic venous bloods. Portal and hepatic venous samples were simultaneously taken from rats at appropriate time points using the perfusion model of 1 mg/mL indinavir at flow rates of 0.05, 0.1, 0.5 and 1.0 mL/min. The indinavir concentrations were assayed by binary-gradient high-pressure liquid chromatography with UV detection. The mean indinavir concentrations in portal vein concentration-time profiles at different perfusion times under various flow rates were all higher than those obtained for hepatic veins. At flow rates of 0.5 and 1.0 mL/min, in particular, the area under the curve (AUC) and maximal concentration (Cmax) of indinavir absorption were significantly different between portal veins and hepatic veins (p < 0.05), indicating considerable hepatic involvement in the presystemic extraction of indinavir. The system also has potential for use when estimating the hepatic extraction ratio (E(H)) and hepatic clearance (Cl(H)). This in vivo approach could provide another useful tool for improving our basic understanding of the absorption kinetics and hepatic metabolism of pharmaceuticals under development and facilitating the clinical application of such.

A TD-DFT investigation of the visible spectra of fluoro-anthraquinones

With ab initio computational chemistry techniques explicitly taking into account electron correlation and solvent effects, we investigate the chemical substitution impact on the λ max of absorption, of 1,2,3,4-tetrafluoro-9,10-anthraquinone. Increasing the electron-donating strength of the auxochromic groups leads to bathochromic displacements. The largest bathochromic effect has been observed when four built-up hydrogen bonds interact with the C O chromophores. For each substitution, the results are rationalized in terms of HOMO and LUMO energy levels, as well as in hydrogen bond effects on the charge separation and bond length in the chromophoric unit.