Favorable Absorption Properties Research Articles

Effects of Mango Pectin Concentration on the Calcium Pectate Bead Properties and on the Cell Leakage of Yeast (Saccharomyces cerevisiae) Immobilized by Entrapment Technique

Immobilized yeast cells have advantages for use in industries due to their stability, viability, and productivity. As a support material, pectin is suitable because of its stability, strong mechanical attributes, and favorable absorption properties. In this study, the influence of mango pectin concentration on the CP bead characteristics and the leakage of immobilized yeast cells were determined. Results have indicated that yeast cells can be immobilized using low-methoxyl pectin (LMP) from mango peels via entrapment technique. Pectin concentration did not affect the size (3.0323 to 3.4315 mm) of the CP beads. Only 5% and 7% (w/v) pectin concentrations produced spherical beads (SF<0.05). Increasing the pectin concentration from 3% to 7% (w/v) resulted in a 36.21% decrease in swelling ratio for CP beads with yeast. The pectin concentration significantly affects the cell leakage (p-value<0.05). The results further indicate the feasibility of using locally available materials as a matrix for immobilization.

Efficient broadband sea urchin-like Fe3O4@C electromagnetic wave absorbing materials

The development of electromagnetic wave absorbing materials is crucial for various applications. Carbon materials and ferrite materials were recognized as ideal candidates of absorbing agents due to their respective dielectric loss and magnetic loss capabilities. In this study, Fe3O4@C were prepared using hydrothermal carbonization coupling method. The microstructure and morphology of Fe3O4@C were studied using SEM, TEM, XRD and TG. The results showed that Fe3O4@C exhibited a hollow sea urchin-like structure. The molar ratio of carbon to iron sources in the raw materials significantly influenced the crystal structure of the product. The growth mechanism of sea urchin-like Fe3O4@C was proposed. The carbon content in Fe3O4@C increased with the increase of molar ratio of glucose and iron (III) sulfate. The Fe3O4@C with carbon content of 31.10 % exhibited optimal absorption performance, with a minimum reflection loss of −57.1 dB at a matching thickness of 5.10 mm and effective absorption bandwidth (EAB) of 4 GHz. Electromagnetic parameters and absorption performance could be adjusted by varying the molar ratio of glucose and iron (III) sulfate. The unique sea urchin-like structure enhanced multiple reflection of electromagnetic waves. Interface polarization, conductivity loss and synergistic effect between carbon and Fe3O4 also contributed to the favorable absorption properties.

PbS quantum dot thin film dry etching

Many consumer products used daily contain sensors and image sensors (smartphones, cars, automated tools, etc.). There is a growing demand to enhance the capabilities of industrial products to probe their environment more efficiently, i.e., under difficult conditions (smoke, darkness, etc.). One solution is to extend the capabilities of image sensors to detect light toward the near-infrared and short-wave infrared (SWIR) regions. Because silicon has weak absorption properties in the infrared, especially in the SWIR region, manufacturers are investigating the use of new materials to build these sensors. To this end, colloidal quantum dot (QD) thin films made from the assembly of PbS nanoparticles have emerged as promising materials. They offer tunable bandgaps, favorable absorption properties, and scalability in production. However, patterning the active parts of photodiodes by plasma etching of this new material presents challenges. The etching chemistry must be selected to volatilize Pb and S without modifying the unetched active part of the PbS QD photodiode, and the etching profile should be anisotropic. In this study, we have screened several plasma operating conditions (power, pressure, and temperature) in various chemistries (H2, Cl2, HBr, and N2). To understand the etch mechanisms and profiles, ToF-SIMS and TEM/energy dispersive x-ray were employed. Our findings reveal that halogen-based plasmas cause QD material deterioration through Cl or Br diffusion deep in the film. While H2 plasmas are efficient to etch PbS QD films, they result in high roughness due to the removal of the carbonated ligands that separate PbS QDs. This ligand etching is followed by QD coalescence leading to significant roughness. However, the addition of N2 to H2 can prevent this phenomenon by forming a diffusion barrier at the surface, resulting in favorable etching characteristics.

Pharmacokinetics of Two Nanoemulsion Formulations of Δ8-Tetrahydrocannabinol in Rats.

The use of Δ8-tetrahydrocannabinol (Δ8-THC) has increased in recent years. Given that the oral absorption of cannabinoids in oil formulations is typically slow and variable, nanoemulsions may be an improved delivery vehicle. Therefore, we characterized the pharmacokinetics (PK) in Sprague-Dawley rats following the administration of three different oral formulations containing 10 mg/kg Δ8-THC: a translucent liquid nanoemulsion, a reconstituted powder nanoemulsion, and a medium chain triglyceride (MCT) oil solution for comparison. Δ8-THC was also administered intravenously at 0.6 mg/kg. Plasma samples were quantified for Δ8-THC and two metabolites, 11-hydroxy-Δ8-THC (11-OH-Δ8-THC) and 11-carboxy-Δ8-THC (COOH-Δ8-THC). Non-compartmental PK parameters were calculated, and a PK model was developed based on pooled data. Despite a smaller median droplet size of the translucent liquid nanoemulsion (26.9 nm) compared to the reconstituted powder nanoemulsion (168 nm), the PK was similar for both. The median Tmax values of Δ8-THC for the nanoemulsions (0.667 and 1 h) were significantly shorter than the median Tmax of Δ8-THC in MCT oil (6 h). This resulted in an approximately 4-fold higher Δ8-THC exposure over the first 4 h for the nanoemulsions relative to the MCT oil solution. The active 11-OH-Δ8-THC metabolite followed a similar pattern to Δ8-THC. The non-compartmental bioavailability estimates of Δ8-THC for the nanoemulsions (11-16.5%) were lower than for the MCT oil solution (>21.5%). However, a model-based analysis indicated similar bioavailability for all three oral formulations. These results demonstrate favorable absorption properties of both nanoemulsions, despite the difference in droplet sizes, compared to an MCT oil formulation.

Synthesis and characterization of kesterite Cu2ZnSn(SxSe1-x)4 thin films with low-cost for efficient solar cells

In this study, we conducted an investigation on the Cu2ZnSnS4 (CZTS) kësterite compound, which is considered an attractive material for its favorable absorption properties, making it a suitable semiconductor for photovoltaic applications. However, its market potential is limited by its low efficiency of 12.6%, primarily caused by the presence of secondary phases that act as recombination centers. Theoretically, the efficiency limit for CZTS ranges from 31% to 33%.To enhance the photovoltaic performance of CZTS, we employed a doping strategy by incorporating selenium (Se) into the Cu2ZnSn(SxSe1-x)4 film, where the sulfur-to-selenium ratio (S/Se) was optimized within the range of 0< x <1. The CZTS films were deposited onto FTO substrates using the spray pyrolysis technique, which is a simple and cost-effective method. The characterization of these films involved X-ray diffraction (XRD) and UV–visible spectroscopy analysis. Additionally, the morphology and topography of the CZTSSe layers were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Transmission electron microscopy (TEM) was also employed.The results obtained in this study indicate that CZTSSe films exhibit band gap values ranging from 1.54 eV to 1.68 eV and grain compactness, with larger agglomerated grains on the film surface when the S/Se ratio is approximately 0.5 or lower. Moreover, the resistivity measurements revealed significant variations when sulfur and selenium were combined, suggesting the influence of their composition on the electrical properties of the CZTS films.

Loosely bonded dual-functionalized ionic liquid-based phase change solvent for energy-saving CO2 capture

A phase change solvent based on a novel loosely bonded dual-functionalized ionic liquids (ILs) containing diethylenetriamine (DETA) and 1-methylimidazole (1-MI), namely [DETA][1-MI], was developed. The strong anion–cation interactions in an ILs inhibited the CO2–ILs interaction and decrease the absorption capacity of the ILs. The weak interaction of [DETA][1-MI] retained most of the absorption capacity of DETA and 1-MI (up to 2.06 mol CO2/mol ILs). When simulated flue gas was fed into the [DETA][1-MI] + dimethylformamide (DMF) + H2O phase change solvent, the CO2-rich phase had a CO2 concentration of up to 6.51 mol CO2/L and a volume ratio of 42.2%. Moreover, a regeneration efficiency of > 90% was maintained even after three regeneration cycles at 393 K. The corresponding regeneration heat (1.40 GJ/ton CO2) was only 36.8% of 30 wt% monoethanolamine (MEA, 3.80 GJ/ton CO2). To the best of our knowledge, it’s well below the reported regeneration energy of amine-based absorbents. In addition, the corrosion rates of the rich and lean phases were only 0.58% and 0.51% of those of the saturated MEA solution, indicating that the corrosivity of [DETA][1-MI] + DMF + H2O was negligible. Moreover, [1-MI]− was observed to promote the formation of m-DETACOO− and HCO3−/CO32−, further enhancing the CO2 absorption capacity. Therefore, the proposed [DETA][1-MI] + DMF + H2O was verified to be a promising absorbent with favorable absorption properties, a low corrosion rate, high cyclic stability, and superior energy efficiency for CO2 capture.

A pure dielectric metamaterial absorber with broadband and thin thickness based on a cross-hole array structure

A pure dielectric metamaterial absorber with broadband and thin thickness is proposed, whose structure is designed as a periodic cross-hole array. The pure dielectric metamaterial absorber with high permittivity is prepared by ceramic reinforced polymer composites. Compared with those with low permittivity, the absorber with high permittivity is more sensitive to structural parameters, which means that it is easier to optimize the equivalent electromagnetic parameters and achieve wide impedance matching by altering the size or shape of the unit cell. The optimized metamaterial absorber exhibits reflection loss below −10 dB in 7.93 GHz–35.76 GHz with a thickness of 3.5 mm, which shows favorable absorption properties under the oblique incidence of TE polarization (±45°). Whether it is a measured or simulated value, the strongest absorbing peak reaches below −45 dB, which exceeds that of most metamaterial absorbers. The distributions of power loss density and electric and magnetic fields are investigated to study the origin of their strong absorbing properties. Multiple resonance mechanisms are proposed to explain the phenomenon, including polarization relaxation of the dielectric and edge effects of the cross-hole array. This work overcomes the shortcomings of the narrow absorbing bandwidth of dielectrics. It demonstrates that the pure dielectric metamaterial absorber with high permittivity has great potential in the field of microwave absorption.

Numerical investigation of the potential of tailored inclusions as noise reduction measures

The reduction of noise and vibrations is an important task in automotive and aircraft industry. Various applications require slender or adjustable reduction measures. Metamaterials formed by a periodic assembly of unit cells consisting of non-homogeneous material decomposition and having topology dependent favorable absorption properties can meet this need. The absorption efficiency of different types of metamaterials has already been proven by various authors. Thereby metamaterials formed by a periodic assembly of tuned mass dampers on plate-like structures or porous layers with rigid inclusions have been investigated. Beyond that, we suggest to design metamaterials consisting of inclusions containing appropriately tuned mass dampers embedded in a material layer and to examine their noise reduction potential. It is investigated, whether besides absorbing energy by exciting the damping device, the orientation of the tuned mass damper is active by purposefully deflecting waves inside the structure. The analysis is carried out applying the Wave Finite Element Method. Using the inverse approach of the Wave Finite Element Method, stop bands, i.e. frequencies for which no free wave propagation is observed, are detected. In a parameter study, the influence of the characteristics of the inclusion on the absorption behavior of the metamaterial is determined.

Designing new quinoline-based organic photosensitizers for dye-sensitized solar cells (DSSC): a theoretical investigation.

In this work, 27 new quinoline-derivative dyes were proposed, and their geometries, electronic structures, and absorption spectra were investigated using density functional theory (DFT) calculations. An important feature found in most of the new compounds was that the lowest unoccupied molecular orbital (LUMO) was above the TiO2 conduction band, facilitating electron transfer from the excited dye to the semiconductor. The energy of the highest occupied molecular orbital (HOMO) was below the reduction potential energy of the electrolyte (I-/I3-), improving the charge regeneration process after photooxidation. Here we present compounds with a small band gap, favorable absorption properties, a D-π-A-type structure that exhibits maximum absorption above 540nm, and a high light harvesting efficiency (LHE > 0.78). The results show that the compounds D1C, D2C, D3C, and R3C could be used as dye sensitizers for dye-sensitized solar cells (DSSCs).

Comparison of the effect of non-esterified and esterified astaxanthins on endurance performance in mice.

Astaxanthin, a natural antioxidant, exists in non-esterified and esterified forms. Although it is known that astaxanthin can improve exercise endurance and cause metabolic improvement in skeletal muscle, the effects of the two different forms are unclear. We investigated the effects of the different forms of astaxanthin on endurance in mice. Eight-week-old ICR mice were divided into four groups: control; astaxanthin extracted from Haematococcus pluvialis in an esterified form; astaxanthin extracted from Phaffia rhodozyma in a non-esterified form; and astaxanthin synthesized chemically in a non-esterified form. After 5 weeks of treatment, each group was divided into sedentary and exercise groups. In the group fed astaxanthin from Haematococcus, the running time to exhaustion was longest, and the plasma and tissue concentrations of astaxanthin were significantly higher than those in the other groups. Astaxanthin from Haematococcus increased 5'-adenosine monophosphate-activated protein kinase levels in the skeletal muscle. Although the mice in the Haematococcus group ran for longer, hexanoyl lysine adduct levels in the skeletal muscle mitochondria were similar in the control and Haematococcus groups. Our results suggested that esterified astaxanthin promoted energy production and protected tissues from oxidative damage during exercise owing to its favorable absorption properties, leading to a longer running time.

Fabrication of CeO2@CdS sub-micron rod arrays for enhanced photoelectrochemical performance

Two-component CeO2@CdS sub-micron rod arrays with enhanced photoelectrochemical properties were fabricated on Ti substrates by electrodeposition. And it is demonstrated that the enhanced photoelectrochemical properties, compared to those of the pristine CeO2, are attributed to the suitable type-II band alignment of CeO2@CdS and the favorable absorption properties of CdS shell.

High-Quality LaVO3 Films as Solar Energy Conversion Material.

Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron-hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron-electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO3 films were grown with defect densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO3 bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO3 films compared to their nonstoichiometric counterparts. This work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.

Solutions of fourth-order parabolic equation modeling thin film growth

In this paper we study the well-posedness for a fourth-order parabolic equation modeling epitaxial thin film growth. Using Kato's Method [1–3] we establish existence, uniqueness and regularity of the solution to the model, in suitable spaces, namely C0([0,T];Lp(Ω)) where p=nα2−α with 1<α<2, n∈N and n≥2. We also show the global existence solution to the nonlinear parabolic equations for small initial data. Our main tools are Lp–Lq-estimates, regularization property of the linear part of e−tΔ2 and successive approximations. Furthermore, we illustrate the qualitative behavior of the approximate solution through some numerical simulations. The approximate solutions exhibit some favorable absorption properties of the model, which highlight the stabilizing effect of our specific formulation of the source term associated with the upward hopping of atoms. Consequently, the solutions describe well some experimentally observed phenomena, which characterize the growth of thin film such as grain coarsening, island formation and thickness growth.

NIR-Absorbing Merocyanine Dyes for BHJ Solar Cells

We have synthesized a series of new, polymethine chain extended merocyanine dyes 1–4 bearing varied acceptor units and an aminothiophene donor moiety. The optical and electronic properties of these new merocyanines have been studied in comparison with their corresponding lower homologues 5–8, which contain two methine groups less, by UV–vis and electro-optical absorption (EOA) spectroscopy and cyclic voltammetry. The absorption spectra of π-extended merocyanines are markedly red-shifted, and their extinction coefficients are significantly increased compared to those of their lower homologues. The photovoltaic characteristics of these dyes have been explored in devices using them as donor and PC61BM fullerene as acceptor materials. Our detailed studies reveal that, despite more favorable absorption properties, the π-extended merocyanines exhibit lower short-circuit current densities (JSC) as well as decreased open-circuit voltages (VOC) and power conversion efficiencies (PCE) compared with those of their r...

Interface Engineering in Inorganic-Absorber Nanostructured Solar Cells.

Nanostructured solar cells have the potential to provide a low-cost alternative to more traditional thin film solar cell technologies. Of particular interest are nanostructured solar cells with inorganic semiconductor absorbers, due to their favorable absorption properties. Such devices include quantum-dot-sensitized solar cells (QDSSCs), extremely thin absorber solar cells (ETASCs), and colloidal quantum dot solar cells (CQDSCs). However, these device architectures suffer from high rates of internal recombination and other problems associated with their extensive internal surface areas. Interfacial surface treatments have proven to be a highly effective means to improve the electronic properties of these devices, leading to overall gains in efficiencies. In this Perspective, we focus on three types of interfacial modification: band alignment by molecular dipole layers, improved CQD film mobilities by ligand exchange, and reduced recombination by interfacial inorganic layers. Select examples in each of these categories are highlighted to provide a detailed look at the underlying mechanisms. We believe that surface modification studies in these devices-QDSSCs, ETASCs, and CQDSCs-are of interest not only to these fields, but also to the broader photovoltaics community.

Energy deposition profile in human skin upon irradiation with a 1,342 nm Nd:YAP laser

Nd:YAP laser emitting at 1,342 nm appears promising for nonablative skin rejuvenation treatment, based on favorable absorption properties of water and melanin in this part of the spectrum. A quantitative determination of energy deposition characteristics of Nd:YAP in normal human skin should enable design of a safe and effective treatment protocol for future human studies. Energy deposition profile of a prototype Nd:YAP laser was determined using pulsed photothermal radiometry. This technique involves time-resolved measurement of mid-infrared emission from a sample after pulsed laser irradiation. The laser-induced temperature depth profile is reconstructed from the radiometric transients using a custom optimization algorithm, developed and tested earlier in our group. Measurements were performed on the extremities of four healthy volunteers at low radiant exposure (2.8 J/cm(2) ). For the purpose of comparison, energy deposition characteristics of commercial Nd:YAG and KTP lasers (at 1,064 and 532 nm, respectively), were also determined at the same test sites. On average, the Nd:YAP laser deposits 50% of the absorbed energy within the top 0.36 mm of skin and 90% within 0.86 mm, which is significantly shallower than the Nd:YAG laser. The ratio between the dermal versus epidermal heating is more favorable and shows a smaller inter- and intra-patient variance as compared to both Nd:YAG and KTP laser. Energy deposition characteristics of the 1,342 nm Nd:YAP laser are very suitable for controlled heating of the upper dermis, as required for nonablative skin rejuvenation. The risks of overheating the epidermis or subcutis should be significantly reduced in comparison with the 1,064 nm Nd:YAG laser.

Utilizing Photocurrent Transients for Dithiolene-Based Photodetection: Stepwise Improvements at Communications Relevant Wavelengths

Photodetection based on bis-(4-dimethylaminodithiobenzil)-Ni(II) (BDN), a representative and well-studied metal dithiolene that shows strong absorption in the near-infrared region of the electromagnetic spectrum, has been investigated. By adopting a metal/insulator/semiconductor/metal (MISM) structure, the peak photocurrent response to an oscillating light chain is increased by up to 50 times, compared to devices without an insulating layer. The transient form of the MISM photoresponse, while unsuitable for steady-state photodetection, can be used to detect periodic light signals of frequencies up to 1 MHz, and is thus applicable for optical communication. Further improvements have been realized by nanostructuring carbon black into the dithiolene layer, improving charge collection, and yielding detectivity of up to 1.6 × 10(11) Jones at wavelengths beyond the scope of silicon photodiodes. Such an architecture may allow the favorable absorption properties of other such metal dithiolenes to be harnessed, where their low charge carrier mobilities and short excitation lifetimes have previously limited their applicability to this field.

Spectroscopic characterization of Nd:Y_2O_3: application toward a differential absorption lidar system for remote sensing of ozone

Neodymium-doped yttria (Nd:Y2O3) is investigated as a solid-state laser material for frequency-tripled generation of ultraviolet laser wavelengths for use in remote sensing of ozone. Emphasis is placed both on the spectroscopy of the fundamental wavelengths at ∼0.914 µm and ∼0.946 µm to assess their feasibility for laser oscillation and on the absorption spectroscopy in the 0.8-µm wavelength region for determination of suitable pump sources. The temperature dependence of the emission and absorption characteristics of Nd:Y2O3 are examined, since aggressive cooling may be required for efficient ∼0.914-µm lasing due to its quasi four-level nature. Data for flash-lamp-pumped laser performance on the 4F3/2→4I11/2 is presented for Nd:Y2O3 and compared with Nd:YAG. Diode-pumped threshold-fluence and threshold-pump energy estimates for Nd:Y2O3 lasing on the 4F3/2→4I9/2 at 0.914 µm and 0.946 µm are calculated based on the data presented here. The measurements presented here for the Nd:Y2O3 indicate favorable absorption and emission properties. Favorable absorption properties in the ∼0.8-µm pump wavelength are compatible with a variety of potential pump sources. Favorable emission properties at reduced temperatures near 150 K indicate that Nd:Y2O3 operating at 0.914 µm and 0.946 µm will have normal-mode laser thresholds similar to that of room-temperature Nd:YAG operating at 0.946 µm. In Q-switched operation, however, Nd:Y2O3 is predicted to exceed the performance of Nd:YAG due to the lower 1.06/0.94 cross-section ratio, which helps to limit amplified spontaneous-emission effects. Although Nd:Y2O3 is not a new material, it has not been the topic of study due to growth problems associated with its high melting point. New advances in growth techniques and the favorable spectroscopic features of Nd:Y2O3 have inspired a new examination of this material.

Synthesis, photochemistry and application of (7-methoxycoumarin-4-yl)methyl-caged 8-bromoadenosine cyclic 3′,5′-monophosphate and 8-bromoguanosine cyclic 3′,5′-monophosphate photolyzed in the nanosecond time region

New caged derivatives of hydrolysis-resistant 8-bromoadenosine cyclic 3′,5′-monophosphate (8-Br-cAMP) and 8-bromoguanosine cyclic 3′,5′-monophosphate (8-Br-cGMP) are described. The compounds are the axial and equatorial isomers of the (7-methoxycoumarin-4-yl)methyl (MCM) esters of cyclic nucleotides. Synthesis is accomplished by treatment of 4-bromomethyl-7-methoxycoumarin with the tetra- n-butylammonium salts of the 8-bromo-substituted cyclic nucleotides or with the free acids of 8-Br-cAMP and 8-Br-cGMP in the presence of silver(I) oxide. MCM-caged 8-Br-cAMP and MCM-caged 8-Br-cGMP liberate 8-Br-cAMP and 8-Br-cGMP during irradiation with ultraviolet light within a few nanoseconds. They show favorable absorption properties and quantum yields and are resistant to hydrolysis in aqueous buffer solutions. The moderate fluorescence properties of the caged compounds in comparison with the strongly fluorescent 4-hydroxymethyl-7-methoxycoumarin (MCM-OH) photoproduct allow the indirect estimation of the amount of photolytically released cyclic nucleotides in aqueous buffer solutions using fluorescence measurements. Their usefulness for physiological studies has been examined in a mammalian cell line expressing the cyclic nucleotide-gated ion channel of bovine olfactory sensory neurons using the patch-clamp technique and confocal laser scanning microscopy. The caged compounds serve as efficient and rapid intracellular sources of 8-Br-cAMP and 8-Br-cGMP. However, at least in HEK 293 cells, fluorescence signals cannot be used to monitor the photolysis of MCM-caged 8-Br-cAMP and 8-Br-cGMP, due to quenching of the fluorescence of MCM-OH.

Schottky-barrier versus homojunction silicon solar cells: a status report

The present state of silicon Schottky-barrier solar cell (s.b.s.c.) development is reviewed and the relative advantages and disadvantages of this type of cell compared with the competing homojunction cell technology. Recent work on cast silicon substrates is considered, and the conclusion drawn that Schottky-barrier cells are not likely to compete unless a wholly thin-film s.b.s.c. can be developed based on the favourable absorption properties of amorphous silicon. A number of problems requiring solution before s.b.s.c. can compete in terms of reliability and low cost for both thick- and thin-film cells are discussed.