Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser...Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser pulses of known energy density through absorbing media allow their absorption parameter determination. The peak energy density w0P of second harmonic pulses of a mode-locked titanium sapphire laser at wavelength λP = 400 nm is determined by nonlinear energy transmission measurement TE through the dye ADS084BE (1,4-bis(9-ethyl-3-car-bazovinylene)-2-methoxy-5-(2’-ethyl-hexyloxy)-benzene) in tetrahydrofuran. TE(w0P) calibration curves are calculated for laser pulse peak energy density reading w0P from measured pulse energy transmissions TE. The ground-state absorption cross-section σP and the excited-state absorption cross-section σex at λP, and the number density N0 of the retinal Schiff base isoform RetA in pH 7.4 buffer of the blue-light adapted recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1 from Chlamydomonas reinhardtii were determined by picosecond titanium sapphire second harmonic laser pulse energy transmission measurement TE through RetA as a function of laser input peak energy density w0P. The complete absorption cross-section spectrum展开更多
AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved b...AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P 【0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA,which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination.展开更多
The analysis of trace elements in human hair for use as biomarkers continues to generate considerable interest in environmental and bioanalytical studies, medical diagnostics, and forensic science. This study investig...The analysis of trace elements in human hair for use as biomarkers continues to generate considerable interest in environmental and bioanalytical studies, medical diagnostics, and forensic science. This study investigated the concentrations of essential and toxic elements (Fe, Mg, Ca, Cu, Zn, Cr, Cd, and Pb) using flame atomic absorption spectroscopy (FAAS) in human scalp hair obtained from subjects living in Forsyth County, North Carolina, USA. The influence of age, sex, race, and smoking habits on the levels of trace elements in the hair samples were also investigated. Additionally, analyses were subjected to a statistical, regression, and principal component analysis to evaluate inter-elemental association and possible pattern recognition in hair samples. Furthermore, Ca/Mg and Zn/Cu ratios, which are often used to evaluate the degree of Ca and Cu utilization in humans and as markers for various health related issues including, atherosclerosis, hypertension, insulin sensitivity, and pancreatic cancer, were calculated. The overall mean concentrations of Fe (25 μg/g), Ca (710 μg/g), Mg (120 μg/g), Zn (190 μg/g), Cu (12 μg/g), and Cr (0.20 μg/g) were found in hair samples. The trace element concentrations varied widely in hair samples as demonstrated by large range of concentrations obtained for each element. However, levels of Cd and Pb elements of <0.030 μg/g were detected in hair sample. In general, the levels of the trace elements in hair samples were poorly correlated. However, significant correlations were found between Ca and Mg (r = 0.840, p = 0.05). The levels of Fe, Ca, Mg, Zn, Cu, and Cr in hair samples and the calculated Ca/Mg and Zn/Cu ratios were found to be largely correlated with age, race, sex, and smoking habits.展开更多
Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-ins...Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.展开更多
In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. Th...In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.展开更多
Absorption enhancement has been considered as an effective way of improving coefficient of performance (COP) of refrigeration systems and magnetic enhancement is one of these methods. A model of magnetic field enhance...Absorption enhancement has been considered as an effective way of improving coefficient of performance (COP) of refrigeration systems and magnetic enhancement is one of these methods. A model of magnetic field enhancement in ammonia-water absorption systems is presented in this paper. A numerical model using finite difference scheme was developed based on the conservation equations and mass transport relationship. Macroscopic magnetic field force was introduced in the momentum equation. The model was validated using data obtained from the literature. Changes in the physical properties of ammonia solution while absorbing both in the direction of falling film and across its thickness were investigated. The magnetic field was found to have some positive effect on the ammonia-water falling film absorption. The results indicate that absorption performance enhancement increased with magnetic intensity. The COP of simple ammonia solution absorption refrigeration system increased by 1.9% and 3.6% for magnetic induction of 1.4 and 3.0 Tesla respectively.展开更多
A comparative research has been developed for acidity and stability constants of M(TTA)1 and M(Asp)2 complexes which have been determined by potentiometric pH titration. Depending on metal ion–binding properties, vit...A comparative research has been developed for acidity and stability constants of M(TTA)1 and M(Asp)2 complexes which have been determined by potentiometric pH titration. Depending on metal ion–binding properties, vital differences in building complex were observed. The present study shows that in M(TTA) complexes, metal ions are coordinated to the carboxyl groups, but in M(Asp) some metal ions are able to build macrochelate over amine group. Hence, the following intermolecular and as a result independent concentration equilibrium between an open–isomer M(Asp)op and a closed–isomer M(Asp)cl, has to be considered cl op. The amounts are reported. The results mentioned above demonstrate that for some M(Asp) complexes the stability constants is also largely determined by the affinity of metal ions for amine group. This leads to a kind of selectivity of metal ions and transfer them via building complexes with the aspartate. The result of this effect is a higher dosage-absorption of minerals in body. Based on the sort of metal ions, the drug-therapy can be different. For heavy metal ions this building complex helps the absorption and filtration of the blood plasma, and consequently the excursion of heavy metal ions takes place. This is an important method in microdialysis. Other metal ions such as the complexes can be considered as mineral carriers. These complexes in certain conditions (PH–range) can release the minerals in body.展开更多
A direct analysis method combining an iminodiacetate extraction disk (IED) with graphite furnace atomic absorption spectrometry was developed for the determination of Co, Ni, Cu, Cd, Sn, Pb, and Bi at sub-ppb levels i...A direct analysis method combining an iminodiacetate extraction disk (IED) with graphite furnace atomic absorption spectrometry was developed for the determination of Co, Ni, Cu, Cd, Sn, Pb, and Bi at sub-ppb levels in water. A 100 mL water sample was adjusted to pH 5.6 with nitric acid and a 1 mol?L–1 ammonium acetate solution, and then passed through an IED (diameter, 47 mm;effective filtering diameter, 35 mm) at a flow rate of 80 - 100 mL?min–1 to preconcentrate seven analytes. The IED was dried at 100?C for 20 min in an electric oven, and 110 - 145 small disks, each 2 mm in diameter, were punched out from the IED. A small disk was introduced into the graphite furnace and atomized according to a heating program. For Cd, Sn, Pb, and Bi measurements, Pd was used as a chemical modifier to enhance the absorbances. Calibration was performed using aqueous standard solutions. The detection limits, corresponding to three times the standard deviation (n = 5) of the blank values, were 0.092 μg·L–1 for Co, 0.12 μg·L–1 for Ni, 0.40 μg·L–1 for Cu, 0.077 μg·L–1 for Cd, 0.92 μg·L–1 for Sn, 0.61 μg·L–1 for Pb, and 0.80 μg·L–1 for Bi with an enrichment factor of 140 using a 100-mL water sample. A spike test for the seven analytes in tap water, rainwater, river water, and mineral drinking water showed quantitative recoveries (93% - 108%).展开更多
GaAs has high three photon absorption (3PA) co-efficient at mid-infrared wavelength like2.2mm and waveguides can be formed with this material like silicon nano-wires. It is shown that three-photon-absorption in GaAs w...GaAs has high three photon absorption (3PA) co-efficient at mid-infrared wavelength like2.2mm and waveguides can be formed with this material like silicon nano-wires. It is shown that three-photon-absorption in GaAs wire waveguide can be utilized to form NAND gate. Three-photon-absorption is incorporated in one-dimensional Finite Difference Time Domain (FDTD) equations. The evolution of a probe pulse under the influence of a pump pulse through crossabsorption in a waveguide is investigated using FDTD simulation, where the dominant process is nonlinear three-photon-absorption. Output probe power dependence on input pump power shows that GaAs waveguide NAND gate has higher extinction ratio in comparison to NAND gate using two-photon-absorption in silicon waveguide.展开更多
The enhanced optical absorption measured by Constant Photocurrent Method (CPM) of hydrogenated nanocrystalline silicon thin films is due mainly to bulk and/or surface light scattering effects. A new numerical method i...The enhanced optical absorption measured by Constant Photocurrent Method (CPM) of hydrogenated nanocrystalline silicon thin films is due mainly to bulk and/or surface light scattering effects. A new numerical method is presented to calculate both true optical absorption and scattering coefficient from CPM absorption spectra of nanotextured nano-crystalline silicon films. Bulk and surface light scattering contributions can be unified through the correlation obtained between the scattering coefficient and surface roughness obtained using our method.展开更多
The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to...The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to their single-functionalities.Herein,a combined Prussian blue analogues derived and catalytical chemical vapor deposition strategy was proposed to produce hierarchical cubic sea urchin-like yolk–shell CoNi@Ndoped carbon(NC)-CoNi@carbon nanotubes(CNTs)mixed-dimensional multicomponent nanocomposites(MCNCs),which were composed of zerodimensional CoNi nanoparticles,three-dimensional NC nanocubes and onedimensional CNTs.Because of good impedance matching and attenuation characteristics,the designed CoNi@NC-CoNi@CNTs mixed-dimensional MCNCs exhibited excellent MA performances,which achieved a minimum reflection loss(RL_(min))of−71.70 dB at 2.78 mm and Radar Cross section value of−53.23 dB m^(2).More importantly,the acquired results demonstrated that CoNi@NC-CoNi@CNTs MCNCs presented excellent photothermal,antimicrobial and anti-corrosion properties owing to their hierarchical cubic sea urchin-like yolk–shell structure,highlighting their potential multifunctional applications.It could be seen that this finding not only presented a generalizable route to produce hierarchical cubic sea urchin-like yolk–shell magnetic NC-CNTs-based mixed-dimensional MCNCs,but also provided an effective strategy to develop multifunctional MCNCs and improve their environmental adaptabilities.展开更多
Differential optical absorption spectroscopy (DOAS) is a useful technique for measuring nitrogen dioxide (NO2) and aerosol, the most important species in urban environmental pollution. This paper reports on the result...Differential optical absorption spectroscopy (DOAS) is a useful technique for measuring nitrogen dioxide (NO2) and aerosol, the most important species in urban environmental pollution. This paper reports on the results of our dual path DOAS measurements recently conducted in Chiba City, Japan, using xenon flashlights equipped on tall constructions as aviation obstruction lights. Because of the proximity of the southern DOAS path to an industrial area, it is found that the level of air pollution generally increases with the dominance of westerly winds, from the plausible source area to the observation light path. This situation is consistent with the result of wind lidar measurement covering a sector of ±28? with the observation range of approximately 2.8 km. In spite of the fact that the two DOAS paths, having path lengths of 5.5 and 3.5 km each, are located in separated regions of Chiba City, the observed temporal behavior was similar for both nitrogen dioxide and aerosol, though the southern path tends to exhibit slightly higher pollution levels than the northern counterpart. Additionally it is confirmed that size information of aerosol particles can be derived from the DOAS data through the analysis of the wavelength dependence of the aerosol optical thickness, which shows fairly good correlation with the mass ratio between PM2.5 and suspended particulate matter (SPM) obtained from the in-situ sampling station measurement. Thus, the DOAS approach can also be utilized for obtaining information on PM2.5 that is considered to be more harmful to human health than SPM.展开更多
The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbi...The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.展开更多
Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usu...Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.展开更多
Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures ...Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures were prepared through digital light processing(DLP)3D printing,polymer-derived ceramics(PDCs),chemical vapor infiltration(CVI),and oxidation technologies.The incorporation of the CVISiC phase effectively increases the dissipation capability,while the synergistic interaction between the gyroid structure and SiO_(2)phase significantly improves impedance matching performance.The SiOC/SiC/SiO_(2)composite achieved a minimum reflection loss(RL min)of-62.2 d B at 4.3 mm,and the effective absorption bandwidth(EAB)covered the X-band,with a thickness range of 4.1 mm-4.65 mm.The CST simulation results explain the broadband and low-frequency absorption characteristics,with an EAB of 8.4 GHz(9.6-18 GHz)and an RL min of-21.5 dB at 5 GHz.The excellent EM wave attenuation performance is associated primarily with polarization loss,conduction loss,the gyroid structure's enhancement of multiple reflections and scattering of EM waves,and the resonance effect between the structural units.The SiOC/SiC/SiO_(2)composite also demonstrated strong mechanical properties,with a maximum compressive failure strength of 31.6 MPa in the height direction.This work opens novel prospects for the development of multifunctional structural wave-absorbing materials suitable for broadband microwave absorption and load-bearing properties.展开更多
A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in environmental samples has been reported. The method is based on the adsorption of Zinc, Iron and Cop...A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in environmental samples has been reported. The method is based on the adsorption of Zinc, Iron and Copper on SDS-coated alumina nanoparticles, which is also modified with 3-mercapto-D-valine. The retained analyte ions on modified solid phase were eluted using 5 mL of 4 mol·L﹣1 HNO3. The analyte determination was carried out by flame atomic absorption spectrometry. The influences of some metal ion and anions on the recoveries of understudy analyte ion were investigated. The influences of the analytical parameters including pH, ligand and SDS amount, eluting solution (type and concentrations) and sample volume on metal ions recoveries were investigated. The extraction efficiency was > 98% with relative standard deviation lower than 3% the method has been successfully applied for the extraction and determination of these ions content in some real samples. Prepared adsorbent was characterized by SEM and FT-IR measurements.展开更多
The bauxite mineral obtained from Araku, Vishakapatnam district of Andhra Pradesh, India is used in the present work. Structural characterization was performed by X-ray diffraction (XRD). The mineral was found to be g...The bauxite mineral obtained from Araku, Vishakapatnam district of Andhra Pradesh, India is used in the present work. Structural characterization was performed by X-ray diffraction (XRD). The mineral was found to be gibbsite in phase. The transitional metal ions present were investigated using electron paramagnetic resonance (EPR) and optical absorption spectra. The EPR results suggest that Fe3+ has replaced Al3+ in the unit cell of bauxite. The optical absorption spectrum is due to Fe3+ which indicates that it is in distorted octahedral environment. The near-infrared (NIR) spectrum is due to water fundamentals and combination overtones, which confirm the formula of the compound. The impurities in the mineral are identified using spectroscopic techniques.展开更多
Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: ...Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: the entrance of Ca2+ across the brush border membranes(BBM) of enterocytes through epithelial Ca2+ channels TRPV6, TRPV5, and Cav1.3; Ca2+ movement from the BBM to the basolateral membranes by binding proteins with high Ca2+ affinity(such as CB9k); and Ca2+ extrusion into the blood. Plasma membrane Ca2+ ATPase(PMCA1b) and sodium calcium exchanger(NCX1) are mainly involved in the exit of Ca2+ from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1 b, since both molecules colocalize and interact. The paracellular pathway consists of Ca2+ transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca2+ transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca2+ absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca2+ transport to control values. Calcitriol [1,25(OH)2D3] is the major controlling hormone of intestinal Ca2+ transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, p ro l a c t i n, g ro w t h h o r m o n e, a n d g l u c o c o r t i c o i d s apparently also regulate Ca2+ transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)2D3 production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca2+ absorption according to Ca2+ demands. Better knowledge of the molecular details of intestinal Ca2+ absorption could lead to the development of nutritional and medical strategies for optimizing the efficiency of intestinal Ca2+ absorption and preventing osteoporosis and other pathologies related to Ca2+ metabolism.展开更多
AIM: To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis(TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. METHOD: The absorption behavior...AIM: To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis(TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. METHOD: The absorption behavior was investigated in an in situ single-pass intestinal perfusion(SPIP) assay in rats. RESULTS: The intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds(jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids(borneol or camphor) was higher than by the monocyclic monoterpenes(menthol or menthone), and promotion by compounds with a hydroxyl group(borneol or menthol) was higher than those with a carbonyl group(camphor or menthone). The apparent permeability coefficient(Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant(Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. CONCLUSION: The intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein(P-gp) and organic cation transporters(OCT), rather than multidrug resistance protein(MRP) and breast cancer resistance protein(BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively.展开更多
FeSiAl magnetically soft alloy hollow microspheres(MSAHMs) were prepared by self-reactive quenching technology based on Fe + Si + AI + KNO_3 reactive systems, in order to obtain absorbents with light weight, low frequ...FeSiAl magnetically soft alloy hollow microspheres(MSAHMs) were prepared by self-reactive quenching technology based on Fe + Si + AI + KNO_3 reactive systems, in order to obtain absorbents with light weight, low frequency and high efficiency. Firstly, twice-balling adhesive precursor method was used to obtain FeSiAl magnetically soft alloy agglomerate powders. Then agglomerate powders with the mesh number of 150-240, 240-325 and 325-400 were sprayed through the flame field into the quenching water. At last, FeSiAl MSAHMs with coarse(average at 86.97 μm), medium(average at 52.16 μm) and fine particles(average at 31.80 μm) were got. Effect of particle size on the phases and microwave absorption properties in low frequency band was studied by XRD and vector network analyzer. The results show that,Fe_3 Si_(0.7)Al_(0.3) and Fe_3 Si_(0.5)Al_(0.5) appear in the phase components of FeSiAl MSAHMs,which is important to improve the microwave absorption properties in low frequency. In addition, the real part(ε′) and imaginary part(ε″) of complex permittivity, the real part(μ′) and imaginary part(μ″) of complex permeability of FeSiAl MSAHMs all present the trend of fine particles > medium particles > coarse particles. The microwave absorption properties in low frequency are improved with the increasing of particle size, and the absorption peak moves to lower frequency range. The properties of fine particles are the best. Their matching thickness of samples is at 5 mm, and the minimum reflectivity is-43 dB at this thickness. The absorption frequency band lower than-10 dB is 4.6-7.6 GHz with a bandwidth of 3 GHz.展开更多
文摘Laser pulse nonlinear transmission measurements through saturable absorbers of known absorption parameters allow the measurement of their energy density. On the other hand, nonlinear transmission measurements of laser pulses of known energy density through absorbing media allow their absorption parameter determination. The peak energy density w0P of second harmonic pulses of a mode-locked titanium sapphire laser at wavelength λP = 400 nm is determined by nonlinear energy transmission measurement TE through the dye ADS084BE (1,4-bis(9-ethyl-3-car-bazovinylene)-2-methoxy-5-(2’-ethyl-hexyloxy)-benzene) in tetrahydrofuran. TE(w0P) calibration curves are calculated for laser pulse peak energy density reading w0P from measured pulse energy transmissions TE. The ground-state absorption cross-section σP and the excited-state absorption cross-section σex at λP, and the number density N0 of the retinal Schiff base isoform RetA in pH 7.4 buffer of the blue-light adapted recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1 from Chlamydomonas reinhardtii were determined by picosecond titanium sapphire second harmonic laser pulse energy transmission measurement TE through RetA as a function of laser input peak energy density w0P. The complete absorption cross-section spectrum
基金Supported by Grant for Promotion of Science from Tottori Bioscience Foundation(1997-1998)Japan and Japanese Government(Ministry of Education,Science and Culture of Japan,MONBUSHO)scholarship No.933241(1994-1999)Japan in part.Dr.Luo was supported by the scholarships.
文摘AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P 【0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA,which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination.
文摘The analysis of trace elements in human hair for use as biomarkers continues to generate considerable interest in environmental and bioanalytical studies, medical diagnostics, and forensic science. This study investigated the concentrations of essential and toxic elements (Fe, Mg, Ca, Cu, Zn, Cr, Cd, and Pb) using flame atomic absorption spectroscopy (FAAS) in human scalp hair obtained from subjects living in Forsyth County, North Carolina, USA. The influence of age, sex, race, and smoking habits on the levels of trace elements in the hair samples were also investigated. Additionally, analyses were subjected to a statistical, regression, and principal component analysis to evaluate inter-elemental association and possible pattern recognition in hair samples. Furthermore, Ca/Mg and Zn/Cu ratios, which are often used to evaluate the degree of Ca and Cu utilization in humans and as markers for various health related issues including, atherosclerosis, hypertension, insulin sensitivity, and pancreatic cancer, were calculated. The overall mean concentrations of Fe (25 μg/g), Ca (710 μg/g), Mg (120 μg/g), Zn (190 μg/g), Cu (12 μg/g), and Cr (0.20 μg/g) were found in hair samples. The trace element concentrations varied widely in hair samples as demonstrated by large range of concentrations obtained for each element. However, levels of Cd and Pb elements of <0.030 μg/g were detected in hair sample. In general, the levels of the trace elements in hair samples were poorly correlated. However, significant correlations were found between Ca and Mg (r = 0.840, p = 0.05). The levels of Fe, Ca, Mg, Zn, Cu, and Cr in hair samples and the calculated Ca/Mg and Zn/Cu ratios were found to be largely correlated with age, race, sex, and smoking habits.
基金supported by the Khalifa University of Science and Technology internal grants(Nos.2021-CIRA-109,2020-CIRA-007,and 2020-CIRA-024).
文摘Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.
文摘In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.
文摘Absorption enhancement has been considered as an effective way of improving coefficient of performance (COP) of refrigeration systems and magnetic enhancement is one of these methods. A model of magnetic field enhancement in ammonia-water absorption systems is presented in this paper. A numerical model using finite difference scheme was developed based on the conservation equations and mass transport relationship. Macroscopic magnetic field force was introduced in the momentum equation. The model was validated using data obtained from the literature. Changes in the physical properties of ammonia solution while absorbing both in the direction of falling film and across its thickness were investigated. The magnetic field was found to have some positive effect on the ammonia-water falling film absorption. The results indicate that absorption performance enhancement increased with magnetic intensity. The COP of simple ammonia solution absorption refrigeration system increased by 1.9% and 3.6% for magnetic induction of 1.4 and 3.0 Tesla respectively.
文摘A comparative research has been developed for acidity and stability constants of M(TTA)1 and M(Asp)2 complexes which have been determined by potentiometric pH titration. Depending on metal ion–binding properties, vital differences in building complex were observed. The present study shows that in M(TTA) complexes, metal ions are coordinated to the carboxyl groups, but in M(Asp) some metal ions are able to build macrochelate over amine group. Hence, the following intermolecular and as a result independent concentration equilibrium between an open–isomer M(Asp)op and a closed–isomer M(Asp)cl, has to be considered cl op. The amounts are reported. The results mentioned above demonstrate that for some M(Asp) complexes the stability constants is also largely determined by the affinity of metal ions for amine group. This leads to a kind of selectivity of metal ions and transfer them via building complexes with the aspartate. The result of this effect is a higher dosage-absorption of minerals in body. Based on the sort of metal ions, the drug-therapy can be different. For heavy metal ions this building complex helps the absorption and filtration of the blood plasma, and consequently the excursion of heavy metal ions takes place. This is an important method in microdialysis. Other metal ions such as the complexes can be considered as mineral carriers. These complexes in certain conditions (PH–range) can release the minerals in body.
文摘A direct analysis method combining an iminodiacetate extraction disk (IED) with graphite furnace atomic absorption spectrometry was developed for the determination of Co, Ni, Cu, Cd, Sn, Pb, and Bi at sub-ppb levels in water. A 100 mL water sample was adjusted to pH 5.6 with nitric acid and a 1 mol?L–1 ammonium acetate solution, and then passed through an IED (diameter, 47 mm;effective filtering diameter, 35 mm) at a flow rate of 80 - 100 mL?min–1 to preconcentrate seven analytes. The IED was dried at 100?C for 20 min in an electric oven, and 110 - 145 small disks, each 2 mm in diameter, were punched out from the IED. A small disk was introduced into the graphite furnace and atomized according to a heating program. For Cd, Sn, Pb, and Bi measurements, Pd was used as a chemical modifier to enhance the absorbances. Calibration was performed using aqueous standard solutions. The detection limits, corresponding to three times the standard deviation (n = 5) of the blank values, were 0.092 μg·L–1 for Co, 0.12 μg·L–1 for Ni, 0.40 μg·L–1 for Cu, 0.077 μg·L–1 for Cd, 0.92 μg·L–1 for Sn, 0.61 μg·L–1 for Pb, and 0.80 μg·L–1 for Bi with an enrichment factor of 140 using a 100-mL water sample. A spike test for the seven analytes in tap water, rainwater, river water, and mineral drinking water showed quantitative recoveries (93% - 108%).
文摘GaAs has high three photon absorption (3PA) co-efficient at mid-infrared wavelength like2.2mm and waveguides can be formed with this material like silicon nano-wires. It is shown that three-photon-absorption in GaAs wire waveguide can be utilized to form NAND gate. Three-photon-absorption is incorporated in one-dimensional Finite Difference Time Domain (FDTD) equations. The evolution of a probe pulse under the influence of a pump pulse through crossabsorption in a waveguide is investigated using FDTD simulation, where the dominant process is nonlinear three-photon-absorption. Output probe power dependence on input pump power shows that GaAs waveguide NAND gate has higher extinction ratio in comparison to NAND gate using two-photon-absorption in silicon waveguide.
文摘The enhanced optical absorption measured by Constant Photocurrent Method (CPM) of hydrogenated nanocrystalline silicon thin films is due mainly to bulk and/or surface light scattering effects. A new numerical method is presented to calculate both true optical absorption and scattering coefficient from CPM absorption spectra of nanotextured nano-crystalline silicon films. Bulk and surface light scattering contributions can be unified through the correlation obtained between the scattering coefficient and surface roughness obtained using our method.
基金support from the National Natural Science Foundation of China(U21A2093)Shaanxi Province Key Research and Development Plan Project(2023-YBGY-461)+4 种基金Platform of Science and Technology and Talent Team Plan of Guizhou province(GCC[2023]007)Guizhou Provincial Basic Research Program(Natural Science)(No.ZK[2025]Key 086)Fok Ying Tung Education Foundation(171095)financial support,Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2024094)。
文摘The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to their single-functionalities.Herein,a combined Prussian blue analogues derived and catalytical chemical vapor deposition strategy was proposed to produce hierarchical cubic sea urchin-like yolk–shell CoNi@Ndoped carbon(NC)-CoNi@carbon nanotubes(CNTs)mixed-dimensional multicomponent nanocomposites(MCNCs),which were composed of zerodimensional CoNi nanoparticles,three-dimensional NC nanocubes and onedimensional CNTs.Because of good impedance matching and attenuation characteristics,the designed CoNi@NC-CoNi@CNTs mixed-dimensional MCNCs exhibited excellent MA performances,which achieved a minimum reflection loss(RL_(min))of−71.70 dB at 2.78 mm and Radar Cross section value of−53.23 dB m^(2).More importantly,the acquired results demonstrated that CoNi@NC-CoNi@CNTs MCNCs presented excellent photothermal,antimicrobial and anti-corrosion properties owing to their hierarchical cubic sea urchin-like yolk–shell structure,highlighting their potential multifunctional applications.It could be seen that this finding not only presented a generalizable route to produce hierarchical cubic sea urchin-like yolk–shell magnetic NC-CNTs-based mixed-dimensional MCNCs,but also provided an effective strategy to develop multifunctional MCNCs and improve their environmental adaptabilities.
文摘Differential optical absorption spectroscopy (DOAS) is a useful technique for measuring nitrogen dioxide (NO2) and aerosol, the most important species in urban environmental pollution. This paper reports on the results of our dual path DOAS measurements recently conducted in Chiba City, Japan, using xenon flashlights equipped on tall constructions as aviation obstruction lights. Because of the proximity of the southern DOAS path to an industrial area, it is found that the level of air pollution generally increases with the dominance of westerly winds, from the plausible source area to the observation light path. This situation is consistent with the result of wind lidar measurement covering a sector of ±28? with the observation range of approximately 2.8 km. In spite of the fact that the two DOAS paths, having path lengths of 5.5 and 3.5 km each, are located in separated regions of Chiba City, the observed temporal behavior was similar for both nitrogen dioxide and aerosol, though the southern path tends to exhibit slightly higher pollution levels than the northern counterpart. Additionally it is confirmed that size information of aerosol particles can be derived from the DOAS data through the analysis of the wavelength dependence of the aerosol optical thickness, which shows fairly good correlation with the mass ratio between PM2.5 and suspended particulate matter (SPM) obtained from the in-situ sampling station measurement. Thus, the DOAS approach can also be utilized for obtaining information on PM2.5 that is considered to be more harmful to human health than SPM.
基金supported by the National Natural Science Foundation of China(No.52436008)the Inner Mongolia Science and Technology Projects,China(Nos.JMRHZX20210003 and 2023YFCY0009)+3 种基金the Huaneng Group Co Ltd.,China(No.HNKJ23-H50)the National Natural Science Foundation of China(No.22408044)the China Postdoctoral Science Foundation(No.2024M761877)the National Key R&D Program of China(No.SQ2024YFD2200039)。
文摘The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.
基金financially supported by the National Natural Science Foundation of China(Nos.22475057 and No.52373262).
文摘Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.
基金financially supported by National Natural Science Foundation of China(Grant Nos.12141203,52202083,W2421013)the Natural Science Foundation Project of Shaanxi Province(Grant No.2024JC-YBMS-450)+1 种基金the Sichuan Science and Technology Program(Grant No.2024YFHZ0265)the Open Project of High-end Equipment Advanced Materials and Manufacturing Technology Laboratory(Grant No.2023KFKT0005)。
文摘Designing materials with both structural load-bearing capacity and broadband electromagnetic(EM)wave absorption properties remains a significant challenge.In this work,SiOC/SiC/SiO_(2)composite with gyroid structures were prepared through digital light processing(DLP)3D printing,polymer-derived ceramics(PDCs),chemical vapor infiltration(CVI),and oxidation technologies.The incorporation of the CVISiC phase effectively increases the dissipation capability,while the synergistic interaction between the gyroid structure and SiO_(2)phase significantly improves impedance matching performance.The SiOC/SiC/SiO_(2)composite achieved a minimum reflection loss(RL min)of-62.2 d B at 4.3 mm,and the effective absorption bandwidth(EAB)covered the X-band,with a thickness range of 4.1 mm-4.65 mm.The CST simulation results explain the broadband and low-frequency absorption characteristics,with an EAB of 8.4 GHz(9.6-18 GHz)and an RL min of-21.5 dB at 5 GHz.The excellent EM wave attenuation performance is associated primarily with polarization loss,conduction loss,the gyroid structure's enhancement of multiple reflections and scattering of EM waves,and the resonance effect between the structural units.The SiOC/SiC/SiO_(2)composite also demonstrated strong mechanical properties,with a maximum compressive failure strength of 31.6 MPa in the height direction.This work opens novel prospects for the development of multifunctional structural wave-absorbing materials suitable for broadband microwave absorption and load-bearing properties.
文摘A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in environmental samples has been reported. The method is based on the adsorption of Zinc, Iron and Copper on SDS-coated alumina nanoparticles, which is also modified with 3-mercapto-D-valine. The retained analyte ions on modified solid phase were eluted using 5 mL of 4 mol·L﹣1 HNO3. The analyte determination was carried out by flame atomic absorption spectrometry. The influences of some metal ion and anions on the recoveries of understudy analyte ion were investigated. The influences of the analytical parameters including pH, ligand and SDS amount, eluting solution (type and concentrations) and sample volume on metal ions recoveries were investigated. The extraction efficiency was > 98% with relative standard deviation lower than 3% the method has been successfully applied for the extraction and determination of these ions content in some real samples. Prepared adsorbent was characterized by SEM and FT-IR measurements.
文摘The bauxite mineral obtained from Araku, Vishakapatnam district of Andhra Pradesh, India is used in the present work. Structural characterization was performed by X-ray diffraction (XRD). The mineral was found to be gibbsite in phase. The transitional metal ions present were investigated using electron paramagnetic resonance (EPR) and optical absorption spectra. The EPR results suggest that Fe3+ has replaced Al3+ in the unit cell of bauxite. The optical absorption spectrum is due to Fe3+ which indicates that it is in distorted octahedral environment. The near-infrared (NIR) spectrum is due to water fundamentals and combination overtones, which confirm the formula of the compound. The impurities in the mineral are identified using spectroscopic techniques.
文摘Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: the entrance of Ca2+ across the brush border membranes(BBM) of enterocytes through epithelial Ca2+ channels TRPV6, TRPV5, and Cav1.3; Ca2+ movement from the BBM to the basolateral membranes by binding proteins with high Ca2+ affinity(such as CB9k); and Ca2+ extrusion into the blood. Plasma membrane Ca2+ ATPase(PMCA1b) and sodium calcium exchanger(NCX1) are mainly involved in the exit of Ca2+ from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1 b, since both molecules colocalize and interact. The paracellular pathway consists of Ca2+ transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca2+ transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca2+ absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca2+ transport to control values. Calcitriol [1,25(OH)2D3] is the major controlling hormone of intestinal Ca2+ transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, p ro l a c t i n, g ro w t h h o r m o n e, a n d g l u c o c o r t i c o i d s apparently also regulate Ca2+ transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)2D3 production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca2+ absorption according to Ca2+ demands. Better knowledge of the molecular details of intestinal Ca2+ absorption could lead to the development of nutritional and medical strategies for optimizing the efficiency of intestinal Ca2+ absorption and preventing osteoporosis and other pathologies related to Ca2+ metabolism.
基金supported by China Pharmaceutical University Training Programs of Innovation for Undergraduates(No.02640390)
文摘AIM: To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis(TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. METHOD: The absorption behavior was investigated in an in situ single-pass intestinal perfusion(SPIP) assay in rats. RESULTS: The intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds(jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids(borneol or camphor) was higher than by the monocyclic monoterpenes(menthol or menthone), and promotion by compounds with a hydroxyl group(borneol or menthol) was higher than those with a carbonyl group(camphor or menthone). The apparent permeability coefficient(Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant(Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. CONCLUSION: The intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein(P-gp) and organic cation transporters(OCT), rather than multidrug resistance protein(MRP) and breast cancer resistance protein(BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively.
基金financial support of National Natural Science Fund of China(No. 51172282)Hebei Natural Science Fund of China (No. E2015506011)
文摘FeSiAl magnetically soft alloy hollow microspheres(MSAHMs) were prepared by self-reactive quenching technology based on Fe + Si + AI + KNO_3 reactive systems, in order to obtain absorbents with light weight, low frequency and high efficiency. Firstly, twice-balling adhesive precursor method was used to obtain FeSiAl magnetically soft alloy agglomerate powders. Then agglomerate powders with the mesh number of 150-240, 240-325 and 325-400 were sprayed through the flame field into the quenching water. At last, FeSiAl MSAHMs with coarse(average at 86.97 μm), medium(average at 52.16 μm) and fine particles(average at 31.80 μm) were got. Effect of particle size on the phases and microwave absorption properties in low frequency band was studied by XRD and vector network analyzer. The results show that,Fe_3 Si_(0.7)Al_(0.3) and Fe_3 Si_(0.5)Al_(0.5) appear in the phase components of FeSiAl MSAHMs,which is important to improve the microwave absorption properties in low frequency. In addition, the real part(ε′) and imaginary part(ε″) of complex permittivity, the real part(μ′) and imaginary part(μ″) of complex permeability of FeSiAl MSAHMs all present the trend of fine particles > medium particles > coarse particles. The microwave absorption properties in low frequency are improved with the increasing of particle size, and the absorption peak moves to lower frequency range. The properties of fine particles are the best. Their matching thickness of samples is at 5 mm, and the minimum reflectivity is-43 dB at this thickness. The absorption frequency band lower than-10 dB is 4.6-7.6 GHz with a bandwidth of 3 GHz.
