Science Letters:Evaluation of a kinetic uricase method for serum uric acid assay by predicting background absorbance of uricase reaction solution with an integrated method

A patented kinetic uricase method was evaluated for serum uric acid assay. Initial absorbance of the reaction mixture before uricase action （A0） was obtained by correcting the absorbance at 293 nm measured before the addition of uricase solution, and background absorbance （Ab） was predicted by an integrated method. Uric acid concentration in reaction solution was calculated from AA, the difference between A0 and Ab, using the absorptivity preset for uric acid. This kinetic uricase method exhibited CV〈4.3% and recovery of 100%. Lipids, bilirubin, hemoglobin, ascorbic acid, reduced glutathione and xanthine 〈0.32 mmol/L in serum had no significant effects. △A linearly responded to 1.2 to 37.5 μmol/L uric acid in reaction solution containing 15 μl serum. The slope of linear response was consistent with the absorptivity preset for uric acid while the intercept was consistent with that for serum alone. Uric acid concentrations in clinic sera by different uricase methods positively correlated to each other. By Bland-Altman analysis, this kinetic uricase method accorded with that by quantifying the total change of UV absorbance on the completion of uricase reaction. These results demonstrated that this kinetic uricase method is reliable for serum uric acid assay with enhanced resistance to both xanthine and other common errors, wider range of linear response and much lower cost.

Calibration-free wavelength modulation spectroscopy for gas concentration measurements under low-absorbance conditions

We derive the expressions of the first and second harmonic signals on the basis of absorption spectral and lock-in theories, and determine the gas concentration according to the ratio of second and first harmonic signals. It is found that the X and Y components of the harmonic signals are influenced by the phase shift between the detection and reference signal, and the phase shift can be any value in a range from 0 to 2π, which is different from the results obtained previously. Meanwhile, an additional item caused by the residual amplitude modulation will make a great contribution to the second harmonic signal, and may not be neglected under low absorbance conditions. Theoretical analysis indicates that subtracting back-ground signal from the second harmonic signal can remove the influence of this item, and can improve the measurement accuracy of gas concentration. On this basis, we select the transition of CO2 at 6527.64 cm-1 to analyse the approximation errors during the derivation by numerical simulation and then measure the CO2 concentration under low absorbance conditions, with absorbance varying from 1‰ to 6‰.

Near-Infrared Spectroscopy Combined with Absorbance Upper Optimization Partial Least Squares Applied to Rapid Analysis of Polysaccharide for Proprietary Chinese Medicine Oral Solution

Near-infrared (NIR) spectroscopy was applied to reagent-free quantitative analysis of polysaccharide of a brand product of proprietary Chinese medicine (PCM) oral solution samples. A novel method, called absorbance upper optimization partial least squares (AUO-PLS), was proposed and successfully applied to the wavelength selection. Based on varied partitioning of the calibration and prediction sample sets, the parameter optimization was performed to achieve stability. On the basis of the AUO-PLS method, the selected upper bound of appropriate absorbance was 1.53 and the corresponding wavebands combination was 400 - 1880 & 2088 - 2346 nm. With the use of random validation samples excluded from the modeling process, the root-mean-square error and correlation coefficient of prediction for polysaccharide were 27.09 mg·L-1 and 0.888, respectively. The results indicate that the NIR prediction values are close to those of the measured values. NIR spectroscopy combined with AUO-PLS method provided a promising tool for quantification of the polysaccharide for PCM oral solution and this technique is rapid and simple when compared with conventional methods.

Corrigendum:A rapid absorbance-based growth assay to screen the toxicity of oligomer Aβ42 and protect against cell death in yeast

In the article titled“A rapid absorbance-based growth assay to screen the toxicity of oligomer Aβ42 and protect against cell death in yeast”,published on pages 1931–1936,Issue 10,Volume 15 of Neural Regeneration Research(Bharadwaj and Martins,2020),there is an error in the title.It should read:A rapid absorbance-based growth assay to screen the toxicity of oligomer Aβ42 and protection against cell death in yeast.

ANALYSIS OF HUMAN PLACENTA BY ^(31)P NUCLEAR MAGNETIC RESONANCE AND THIN-LAYER CHROMATOGRAPHY SCANNING COMBINED WITH THE CORRECTIVE METHOD OF ABSORBANCE PROPORTIONAL COEFFICIENT

Five phospholipids in human placenta were determined by phosphorus 31 nuclear magnetic resonance(^(31)P NMR)spectroscopy and thin-layer chromatography(TLC) scanning combined with the corrective method of absorbance proportional coefficient. The NMR spectrometer used this investigation was a Bruker AM-500 spectrometer operating at 202.4 MHz for ^(31)P chemical shifts are relative to 85% phosphoric acid. TIC was carried out by silica gel H plate developed in chloroform-methanol-glacial acetic acid-ethanol-water(25:4:6:2:0.5),with Vaskovsky reagent as colour -developing agent of phospholipids.

Correlation of fibrinogen level and absorbance change in both PT and APTT clotting curves on BCSXP

Objective： To investigate the correlation of fibrinogen level and absorbance change in both PT and APTT clotting curves on BCSXP Analyzer. Methods：A serial of standard fibrinogen and 250 patient plasma samples with different qualities（normal, hemolysis, icterus, and lipemia） were run on BCSXP for assays PT, APTT and Fibrinogen. The absorbance change（DeltaA） from baseline to plateau in clotting curve was retrieved and analyzed on its correlation with the Fibrinogen result. Influence of plasma quality and PT/ APTT result on this correlation was also studied respectively. Results：Both PT-DeltaA and APTT-DeltaA showed good linear regres- sion with fibrinogen level in the sample, with R2 close to 0.90 in both standard and patient samples. Hemolysis（H）, itcterus（I） and lipemia（L） of the sample with valid clotting curves were found to have no significant difference in this correlation from normal（N） sample（R2： 0.83H, 0.92I, 0.81L and 0.79N in PT; 0.89H, 0.95l, 0.91L and 0.89N in APTT） in either PT or APTT curve. PT or APTT result also has little impact on this correlation（0.71 in range 7 - 10 sec, 0.56 inl0 - 20 sec, and 0.70 in 20 sec-; R2 in APTT： 0.88 in 20-30 sec, 0.92 in 30-40 sec, and 0.95 in 40 sec-）. Conclusion：The absorbance change in either PT or APTT clotting curve correlates well with the fibrinogen level in plasma, which is independent of plasma quality PT or APTT results. The absorbance change can be used as an alternative way to roughly estimate fibrinogen level in either PT or APTT clotting curve when the result of clauss-based fibrinogen measurement is not available.

External Electric Field Dependence of Optical Absorbance in SnO_2 Nanoclusters

The optical absorbance in near UV wavelength region in SnO 2 nanoclusters in an external electric field is determined at room temperature. The absorbance spectra as applied field and the absorbance variations with the applied field are obtained.The relation between absorbance change and applied field is non-linear, and is saturated at high field region.

The Effects of Antiretroviral Drugs on the Absorbance Characteristics of HIV-Infected Blood

In the twenty first century research works, there may be a need to achieve a more reliable research result through a synergy between engineers and biological researchers. The peak absorbance data for various interacting systems were measured. These were used to show that the antiretroviral drug has the effect of increasing the peak absorbance values of both the uninfected and infected blood components, i.e., the drugs are made able to increase the light absorption capacity of the blood cells. For drug 2 that contains three components including Efavirenz, the drug effect on lymphocytes was increased by about 38% for patients that had been on antiretroviral drug treatment. Mathematical models were proposed and used in determining the coating effectiveness of antiretroviral drugs in the presence and absence of HIV. The use of the findings of this work by pharmaceutical industries may help in the search for more effective antiretroviral drugs for the treatment of HIV patients.

Effect of Deposition Temperature on the FTIR Absorbance of Zinc Oxide Thin Films Produced by MOCVD

Metalorganic chemical vapour deposition (MOCVD) method was used to deposit zinc oxide thin films on soda-lime glass substrates at temperatures of 330°C, 360°C, 390°C and 420°C, using zinc acetate as the precursor. Compressed air was used as the carrier gas at a flow rate of 2.5 dm3 per minute. Each deposition was carried out for two hours under atmospheric pressure. FTIR measurements were subsequently made on the produced thin films to determine their struc ture and trend with deposition temperatures. The measurements showed the presence of lingering functional groups of organic, oxide and nitride origin, which prominently moderated the natural vibrational modes of the material within their respective affiliate wavenumbers, as well as three slight but evident trends in absorbance peaks, cut-off wave length, and the existence of the functional groups with temperature. The produced materials are expected to be useful for enhanced solar cells, triggering sensor devices, p-doped zinc oxide, etc.

Optical and Morphological Properties of Carbon Nanotube—Anatase Nanocomposites: Improvements in Visible Absorbance

In this work, we present the growth and optical characterization of carbon nanotube/TiO2 anatase nanocomposites. The composites are obtained by doping a bulk of anatase nanometric grains with different weight percentages of carbon nanotube (from 0.1% to 50%). We observe that only for tube concentrations between 0.1% and 2%, the growth process shows the formation of a matrix where carbon nanotubes are uniformed and dispersed in a bulk of TiO2 grains. Moreover, the X-ray photoelectron spectroscopy and surface morphology analysis (conducted from AFM images) indicated that the CNT absorption is a simple physisorption without chemical bonds formations between tube and dioxide. Finally, absorption in all the visible range has the increase of about 60% at very low concentration (2%) of carbon nanotubes.

Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light

Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter（DOM） was investigated in this study. Solar light significantly decreased the UV_（254） absorbance and fluorescence（FLU） intensity of reclaimed water.However, its effect on the dissolved organic carbon（DOC） value of reclaimed water was very limited. The decrease in the UV_（254） absorbance intensity and FLU excitation–emission matrix regional integration volume（FLU volume） of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV_（254） absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV_（254） absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV_（254） and FLU intensity were independent of light intensity. The peaks of the UV_（254） absorbance and FLU intensity with an apparent molecular weight（AMW） of 100 Da to 2000 Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change.

DETERMINATION OF THE MOLE ABSORBANCE COEFFICIENT AND DISSOCIATION CONSTANT OF THE COLOR COORDINATION COMPOUND BY MEANS OF NONLINEAR PROGRAMMING

When a coordinate equilibrium is MRn-1+R（?）MRn, we can express the dissociation constant Kn as follows:

Contrasting altitudinal patterns of leaf UV reflectance and absorbance in four herbaceous species on the Qinghai-Tibetan Plateau

Aims Alpine plants have to cope with intense ultraviolet(UV)radiation and its altitudinal changes.It has been argued that leaf UV reflec-tance and absorbance should play a central role in acclimation and adaptation to changes in UV radiation,but evidence is lim-ited from high altitudinal ecosystems.In this study,we assessed whether leaf UV reflectance and leaf pigments jointly vary with altitude in alpine broadleaved herbaceous species.The primary hypothesis is that leaves with higher UV reflectance should have lower UV absorbance and/or lower contents of photosynthetic pigments.Methods Leaf UV reflectance,leaf UV absorbance and photosynthetic pig-ments(chlorophyll a and b,carotenoids)were examined in four broadleaved herbaceous species in relation to their habitat alti-tudes.The leaf surface reflectance and leaf extract absorbance at wavelengths of 305 and 360 nm were measured to examine the leaf optical and photochemical characteristics in the UV-B and UV-A bands,respectively.The species included Saussurea katochaete Maxim.,Saussurea pulchra Lipsch.,Anaphalis lactea Maxim.and Rheum pumilum Maxim.,which are distributed along the same slope from 3200 to 4200 m in the Qilian Mountains,Qinghai-Tibetan Plateau.Important Findings The leaf UV absorbance was approximately twice as high at 305 nm(UV-B)than at 360 nm(UV-A)for all species except R.pumilum.Among the four species,the leaf UV absorbance was the highest and almost all values were within 2-6 Abs cm^(−2)(absorbance cm^(−2))in S.pulchra,but the lowest(frequently<1 Abs cm^(−2))were observed in R.pumilum.Only R.pumilum showed significantly higher values at higher elevations.Leaf UV reflectance was generally higher at higher elevations for all species except for A.lactea,and exhibited much larger altitudinal variations compared to leaf UV absorbance.Anaphalis lactea showed a very high UV reflectance even at low altitudes.Among the four species,photosynthetic pigments tended to decrease with an increase in leaf UV reflectance but increased with leaf UV absorbance.The study suggests that leaf UV reflec-tance,rather than leaf UV absorbance,plays a more active role in acclimation to altitudinal changes in UV radiation,and a high investment in leaf UV reflectance may limit the accumulation of photosynthetic pigments in alpine plants.

Multiscattering-enhanced absorbance to enable the sensitive analysis of extremely diluted biological samples: Determination of oxidative potential in exhaled air

Direct determination of the oxidative potential in exhaled air(OPEA)as a biological indicator of the redox balance status in airways requires an extremely sensitive sensing approach to counterbalance the high dilution of the exhaled air matrix.In opposite to standard colorimetric assays based on Beer-Lambert Law,the use of simple multiscattering-enhanced absorbance(MEA)strategy results in an improved photonic sensing system.Based on this strategy and using the ferrous-xylenol orange assay,analytical performances allowing the detection of 3 pmol of H_(2)O_(2) could be obtained.The comparative analysis of photometric configurations–standard vs MEA–highlights the large absorbance gain obtained for tiny H_(2)O_(2) amounts–from 0 to 30 pmol–whereas similar sensing trends are observed at higher concentration range.The automated introduction of exhaled air sample into the reaction compartment via needle-impinger coupled with the MEA-based photonic cell enables ultrasensitive determination of OPEA in short time(<5 min).A pilot study conducted on healthy subjects(n=22)and chronic obstructive pulmonary disease(COPD)patients(n=23)volunteers shows a significant increase of the OPEA for COPD versus controls and strong negative correlation between OPEA and spirometry parameters(Tiffeneau index:FEV1/FVC)for ex-/non-smokers.Application perspectives to assess inflammatory episodes in obstructive lung diseases are thus made possible using this sensing approach.

Multiphase Interfacial Regulation Based on Hierarchical Porous Molybdenum Selenide to Build Anticorrosive and Multiband Tailorable Absorbers

Electromagnetic wave(EMW)absorbing materials have an irreplaceable position in the field of military stealth as well as in the field of electromagnetic pollution control.And in order to cope with the complex electromagnetic environment,the design of multifunctional and multiband high efficiency EMW absorbers remains a tremendous challenge.In this work,we designed a three-dimensional porous structure via the salt melt synthesis strategy to optimize the impedance matching of the absorber.Also,through interfacial engineering,a molybdenum carbide transition layer was introduced between the molybdenum selenide nanoparticles and the three-dimensional porous carbon matrix to improve the absorption behavior of the absorber.The analysis indicates that the number and components of the heterogeneous interfaces have a significant impact on the EMW absorption performance of the absorber due to mechanisms such as interfacial polarization and conduction loss introduced by interfacial engineering.Wherein,the prepared MoSe_(2)/MoC/PNC composites showed excellent EMW absorption performance in C,X,and Ku bands,especially exhibiting a reflection loss of−59.09 dB and an effective absorption bandwidth of 6.96 GHz at 1.9 mm.The coordination between structure and components endows the absorber with strong absorption,broad bandwidth,thin thickness,and multi-frequency absorption characteristics.Remarkably,it can effectively reinforce the marine anticorrosion property of the epoxy resin coating on Q235 steel substrate.This study contributes to a deeper understanding of the relationship between interfacial engineering and the performance of EMW absorbers,and provides a reference for the design of multifunctional,multiband EMW absorption materials.

Ultra-broadband microwave absorber and high-performance pressure sensor based on aramid nanofiber,polypyrrole and nickel porous aerogel

Electronic devices have become ubiquitous in our daily lives,leading to a surge in the use of microwave absorbers and wearable sensor devices across various sectors.A prime example of this trend is the aramid nanofibers/polypyrrole/nickel(APN)aerogels,which serve dual roles as both microwave absorbers and pressure sensors.In this work,we focused on the preparation of aramid nanofibers/polypyrrole(AP15)aerogels,where the mass ratio of aramid nanofibers to pyrrole was 1:5.We employed the oxidative polymerization method for the preparation process.Following this,nickel was thermally evaporated onto the surface of the AP15 aerogels,resulting in the creation of an ultralight(9.35 mg·cm^(-3)).This aerogel exhibited a porous structure.The introduction of nickel into the aerogel aimed to enhance magnetic loss and adjust impedance matching,thereby improving electromagnetic wave absorption performance.The minimum reflection loss value achieved was-48.7 dB,and the maximum effective absorption bandwidth spanned 8.42 GHz with a thickness of 2.9 mm.These impressive metrics can be attributed to the three-dimensional network porous structure of the aerogel and perfect impedance matching.Moreover,the use of aramid nanofibers and a three-dimensional hole structure endowed the APN aerogels with good insulation,flame-retardant properties,and compression resilience.Even under a compression strain of 50%,the aerogel maintained its resilience over 500 cycles.The incorporation of polypyrrole and nickel particles further enhanced the conductivity of the aerogel.Consequently,the final APN aerogel sensor demonstrated high sensitivity(10.78 kPa-1)and thermal stability.In conclusion,the APN aerogels hold significant promise as ultra-broadband microwave absorbers and pressure sensors.

Vibration Reduction by a Partitioned Dynamic Vibration Absorber with Acoustic Black Hole Features

Vibration quality is a vital indicator for assessing the progress of modern equipment.The dynamic vibration absorber(DVA)based on the acoustic black hole(ABH)feature is a new passive control method that manipulates waves.It offers efficient energy focalization and broad-spectrum vibration suppression,making it highly promising for applications in large equipment such as aircraft,trains,and ships.Despite previous advancements in ABH-DVA development,certain challenges remain,particularly in ensuring effective coupling with host structures during control.To address these issues,this study proposes a partitioned ABH-featured dynamic vibration absorber(PABH-DVA)with partitions in the radial direction of the disc.By employing a plate as the host structure,simulations and experiments were conducted,demonstrating that the PABH-DVA outperforms the original symmetric ABH-DVA in terms of damping performance.The study also calculated and compared the coupling coefficients of the two ABH-DVAs to uncover the mechanism behind the enhanced damping.Simulation results revealed that the PABH-DVA exhibits more coupled modes,occasionally with lower coupling coefficients than the symmetric ABH-DVA.The influence of frequency ratio and modal mass was further analyzed to explain the reasons behind the PABH-DVA's superior damping performance.Additionally,the study discussed the impact of the number of slits and their orientation.This research further explains the coupling mechanism between the ABH-DVA and the controlled structure,and provides new ideas for the further application of ABH in engineering.

Designing Symmetric Gradient Honeycomb Structures with Carbon‑Coated Iron‑Based Composites for High‑Efficiency Microwave Absorption

The impedance matching of absorbers is a vital factor affecting their microwave absorption(MA)properties.In this work,we controllably synthesized Material of Institute Lavoisier 88C(MIL-88C)with varying aspect ratios(AR)as a precursor by regulating oil bath conditions,followed by one-step thermal decomposition to obtain carbon-coated iron-based composites.Modifying the precursor MIL-88C(Fe)preparation conditions,such as the molar ratio between metal ions and organic ligands(M/O),oil bath temperature,and oil bath time,influenced the phases,graphitization degree,and AR of the derivatives,enabling low filler loading,achieving well-matched impedance,and ensuring outstanding MA properties.The MOF-derivatives 2(MD_(2))/polyvinylidene Difluoride(PVDF),MD_(3)/PVDF,and MD4/PVDF absorbers all exhibited excellent MA properties with optimal filler loadings below 20 wt%and as low as 5 wt%.The MD_(2)/PVDF(5 wt%)achieved a maximum effective absorption bandwidth(EAB)of 5.52 GHz(1.90 mm).The MD_(3)/PVDF(10 wt%)possessed a minimum reflection loss(RL_(min))value of−67.4 at 12.56 GHz(2.13 mm).A symmetric gradient honeycomb structure(SGHS)was constructed utilizing the high-frequency structure simulator(HFSS)to further extend the EAB,achieving an EAB of 14.6 GHz and a RL_(min) of−59.0 dB.This research offers a viable inspiration to creating structures or materials with high-efficiency MA properties.

Manganese dioxide as wide adaptive ultrafast photonic device for pulsed laser generation

Research on novel ultrafast photonic devices with wide adaptability has become important scientific technical means to realize both scheme innovation and performance breakthrough in fiber laser generation.As types of transition metal oxide,manganese dioxide(MnO_(2))materials exhibit remarkable properties including high photothermal stability,strong oxidation resistance,and excellent optical properties,making them promising candidate for utilization as modulation devices in nonlinear optics and ultrafast optics fields.We investigate the impact of MnO_(2)-based saturable absorber(SA)on the pulse characteristics.The experiment reveals that MnO_(2)-based SA supports effectively pulsed laser generation in wide pump power range and large dispersion parameter space with signal-to-noise ratio more than 85 dB.As far as we know,the pump power response range is outstanding among the most of the reported pulsed lasers,which is attributed to the large modulation depth of MnO_(2) SA.We also investigate the impact of dispersion on the characteristics of laser output,which is not involved in other similar works.This research indicates that MnO_(2) as a photonic device has vast potential in advanced ultrafast optics.

Optical Nonlinearity of Violet Phosphorus and Applications in Fiber Lasers

A D-shaped fiber is coated with a new two-dimensional nanomaterial,violet phosphorus(VP),to create a saturable absorber(SA)with a modulation depth of 3.68%.Subsequently,the SA is inserted into a fiber laser,enabling successful generation of dark solitons and bright–dark soliton pairs through adjustment of the polarization state within the cavity.Through further study,mode-locked pulses are achieved,proving the existence of polarization-locked vector solitons.The results indicate that VP can be used as a polarization-independent SA.