Absorption Spectrometer Research Articles

Generation and Investigation of FE2O3 Nanoparticles’ Optical Properties and Antibacterial Activity Using Pulsed Laser Ablation in Deionized Water

The synthesis of metallic nanoparticles has ignited intense interest over the last decade due to their unique properties, which make them applicable in a variety of fields of science and technology. In this study, iron oxide nanoparticles (Fe2O3 NPs) were synthesized, characterized, and their antibacterial activity was determined using a low-cost and simple method. Method: In this paper, magnetic nanoparticles were synthesized by a physical method of pulsed laser ablation in a liquid medium with 600 mJ energy. Magnetic Fe2O3 NPs were prepared by using a 1064 nm Nd-YAG laser and bombarding the [Formula: see text]-Fe2O3 target in a deionized aqueous solution. An absorption spectrometer was used to study the optical properties and structures of nanoparticles, the prepared nanoparticles were analyzed using Fourier transform infrared (FTIR) spectroscopy. Besides, utilizing FESEM, the morphological and surface characteristics were examined. The antibacterial activity of Fe2O3 NPs against several pathogenic Gram-positive and Gram-negative bacteria isolated from various human infection sites was investigated using a disk diffusion experiment with laser pulse lengths of (100 nm, 150 nm, 200 nm and 300 nm) with the same laser energy. Result: The results showed the success of this method as the first sign that can be inferred from the change in the color of the solution to prepare nanoparticles. Fe2O3 NPs are mostly spherical in shape, with nano sizes ranging between 66.7 nm and 9.5 nm. The energy gap was found to be in the range of 1.79–2.39 eV for almost all nanoparticles prepared. Fe2O3 NPs were formed in almost spherical surface morphology with regular size and shape. The results showed their effect on stopping the growth of bacteria of type E. coli maximum zone of inhibition of 20 mm and 19 mm of S. epidermidis, 18 mm of type S. mutans and 16 mm of P. aeruginosa. As a result, in this study, it was shown that Fe2O3 NPs produced in water by laser ablation method can be used as antibacterial agents due to these properties.

Direct fabrication of metal-free graphene nanohairs/polyimide heterojunction for the highly efficient photocatalytic degradation of industrial dyes

A single-step three-dimensional graphene nanohairs/polyimide heterojunction (GPH) is fabricated using a CO2 laser-assisted method. An optimization process has been systematically carried out to obtain high-quality graphene nanohairs on polyimide. The obtained GPH was characterized by X-Ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. Using the fabricated GPH as a photocatalyst, the photocatalytic degradation of three industrial dyes namely, methyl orange (MO), methylene blue (MB), and Rhodamine B (RhB), was studied under UV irradiation. The decolorization of the samples was studied by UV–vis absorbance spectrometer. Starting from 5 ppm dye solutions with GPH, the degradation efficiencies of 97 % for MO in 60 min, 98 % for RhB in 90 min, and 88 % for MB in 170 min, were achieved. Furthermore, the stability of GPH was evaluated and after five runs, the degradation efficiency of MO, RhB and MB is decreased to 85 %, 91 % and 75 % from 98 %, 97 %, and 88 %, respectively. The mechanism for the degradation of dyes using GPH was proposed. The simple and feasible fabrication of GPH with excellent photocatalytic dye degradation efficiency would create the new insight into the flexible heterostructures for degrading the industrial wastewater treatment process.

Airborne observations of peroxy radicals during the EMeRGe campaign in Europe

Abstract. In this study, airborne measurements of the sum of hydroperoxyl (HO2) and organic peroxy (RO2) radicals that react with nitrogen monoxide (NO) to produce nitrogen dioxide (NO2), coupled with actinometry and other key trace gases measurements, have been used to test the current understanding of the fast photochemistry in the outflow of major population centres. The measurements were made during the airborne campaign of the EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales) project in Europe on board the High Altitude and Long Range Research Aircraft (HALO). The measurements of RO2∗ on HALO were made using the in situ instrument Peroxy Radical Chemical Enhancement and Absorption Spectrometer (PeRCEAS). RO2∗ is to a good approximation the sum of peroxy radicals reacting with NO to produce NO2. RO2∗ mixing ratios up to 120 pptv were observed in air masses of different origins and composition under different local actinometric conditions during seven HALO research flights in July 2017 over Europe. Radical production rates were estimated using knowledge of the photolysis frequencies and the RO2∗ precursor concentrations measured on board, as well as the relevant rate coefficients. Generally, high RO2∗ concentrations were measured in air masses with high production rates. In the air masses investigated, RO2∗ is primarily produced by the reaction of O1D with water vapour and the photolysis of nitrous acid (HONO) and of the oxygenated volatile organic compounds (OVOCs, e.g. formaldehyde (HCHO) and glyoxal (CHOCHO)). Due to their short lifetime in most environments, the RO2∗ concentrations are expected to be in a photostationary steady state (PSS), i.e. a balance between production and loss rates is assumed. The RO2∗ production and loss rates and the suitability of PSS assumptions to estimate the RO2∗ mixing ratios and variability during the airborne observations are discussed. The PSS assumption for RO2∗ is considered robust enough to calculate RO2∗ mixing ratios for most conditions encountered in the air masses measured. The similarities and discrepancies between measured and PSS calculated RO2∗ mixing ratios are discussed. The dominant terminating processes for RO2∗ in the pollution plumes measured up to 2000 m are the formation of nitrous acid, nitric acid, and organic nitrates. Above 2000 m, HO2–HO2 and HO2–RO2 reactions dominate the RO2∗ removal. RO2∗ calculations by the PSS analytical expression inside the pollution plumes probed often underestimated the measurements. The underestimation is attributed to the limitations of the PSS equation used for the analysis. In particular, this expression does not account for the yields of RO2∗ from the oxidation and photolysis of volatile organic compounds, VOCs, and OVOCs other than those measured during the EMeRGe research flights in Europe. In air masses with NO mixing ratios ≤50 pptv and low VOC/NO ratios, the RO2∗ measured is overestimated by the analytical expression. This may be caused by the formation of H2O and O2 from OH and HO2, being about 4 times faster than the rate of the OH oxidation reaction of the dominant OVOCs considered.

Mercury toxicology in Epinephelidae fishes: A multiple tissue approach in two groupers species from southwestern Atlantic (SE-Brazil)

Epinephelidae fishes are important to reef ecosystems, as well as for commercial fishing and cultural heritage. Additionally, most of these species are at some risk of extinction, as Epinephelus marginatus and Hyporthodus nigritus. This study aimed to determine total mercury (THg) concentrations and burden on eight tissues of E. marginatus and H. nigritus. A Cold Vapor/Atomic Absorption Spectrometer was used for the THg determination. THg concentrations and burden varied significantly between tissues in both species. The highest concentrations were determined in the liver, and the greatest burden was in muscle. The gonad concentrations were higher than the toxicological threshold. General trends of increase in THg concentrations and burden along growth were observed. Mercury is a threat for both species evaluated, raising this concern for other Epinephelidae species.

Northern Hemisphere atmospheric history of carbon monoxide since preindustrial times reconstructed from multiple Greenland ice cores

Abstract. Carbon monoxide (CO) is a regulated pollutant and one of the key components determining the oxidizing capacity of the atmosphere. Obtaining a reliable record of atmospheric CO mixing ratios ([CO]) since preindustrial times is necessary to evaluate climate–chemistry models under conditions different from today and to constrain past CO sources. We present high-resolution measurements of CO mixing ratios from ice cores drilled at five different sites on the Greenland ice sheet that experience a range of snow accumulation rates, mean surface temperatures, and different chemical compositions. An optical-feedback cavity-enhanced absorption spectrometer (OF-CEAS) was coupled with continuous melter systems and operated during four analytical campaigns conducted between 2013 and 2019. Overall, continuous flow analysis (CFA) of CO was carried out on over 700 m of ice. The CFA-based CO measurements exhibit excellent external precision (ranging from 3.3 to 6.6 ppbv, 1σ) and achieve consistently low blanks (ranging from 4.1±1.2 to 12.6±4.4 ppbv), enabling paleoatmospheric interpretations. However, the five CO records all exhibit variability that is too large and rapid to reflect past atmospheric mixing ratio changes. Complementary tests conducted on discrete ice samples demonstrate that these variations are not artifacts of the analytical method (i.e., production of CO from organics in the ice during melting) but are very likely related to in situ CO production within the ice before analysis. Evaluation of the signal resolution and co-investigation of high-resolution records of CO and total organic carbon (TOC) suggest that past atmospheric CO variations can be extracted from the records' baselines with accumulation rates higher than 20 cm w.e.yr-1 (water equivalent per year). Consistent baseline CO records from four Greenland sites are combined to produce a multisite average ice core reconstruction of past atmospheric CO for the Northern Hemisphere high latitudes, covering the period from 1700 to 1957 CE. Such a reconstruction should be taken as an upper bound of past atmospheric CO abundance. From 1700 to 1875 CE, the record reveals stable or slightly increasing values in the 100–115 ppbv range. From 1875 to 1957 CE, the record indicates a monotonic increase from 114±4 to 147±6 ppbv. The ice core multisite CO record exhibits an excellent overlap with the atmospheric CO record from Greenland firn air which spans the 1950–2010 CE time period. The combined ice core and firn air CO history, spanning 1700–2010 CE, provides useful constraints for future model studies of atmospheric changes since the preindustrial period.

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO 2 Bioreduction

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO ₂ Bioreduction

Reactive nitrogen fluxes over peatland and forest ecosystems using micrometeorological measurement techniques

Abstract. Interactions of reactive nitrogen (Nr) compounds between the atmosphere and the earth's surface play a key role in atmospheric chemistry and in understanding nutrient cycling of terrestrial ecosystems. While continuous observations of inert greenhouse gases through micrometeorological flux measurements have become a common procedure, information about temporal dynamics and longer-term budgets of Nr compounds is still extremely limited. Within the framework of the research projects NITROSPHERE and FORESTFLUX, field campaigns were carried out to investigate the biosphere–atmosphere exchange of selected Nr compounds over different land surfaces. The aim of the campaigns was to test and establish novel measurement techniques in eddy-covariance setups for continuous determination of surface fluxes of ammonia (NH3) and total reactive nitrogen (ΣNr) using two different analytical devices. While high-frequency measurements of NH3 were conducted with a quantum cascade laser (QCL) absorption spectrometer, a custom-built converter called Total Reactive Atmospheric Nitrogen Converter (TRANC) connected and operated upstream of a chemiluminescence detector (CLD) was used for the measurement of ΣNr. As high-resolution data of Nr surface–atmosphere exchange are still scarce but highly desired for testing and validating local inferential and larger-scale models, we provide access to campaign data including concentrations, fluxes, and ancillary measurements of meteorological parameters. Campaigns (n=4) were carried out in natural (forest) and semi-natural (peatland) ecosystem types. The published datasets stress the importance of recent advancements in laser spectrometry and help improve our understanding of the temporal variability of surface–atmosphere exchange in different ecosystems, thereby providing validation opportunities for inferential models simulating the exchange of reactive nitrogen. The dataset has been placed in the Zenodo repository (https://doi.org/10.5281/zenodo.4513854; Brümmer et al., 2022) and contains individual data files for each campaign.

Seasonal content of heavy metals in the "soil-feed-milk-manure" system in horse husbandry in Kazakhstan.

Background and Aim:The quality of food, especially animal-based food, is crucial for human health. However, the quality of milk and other animal products has become an acute cause for concern in Kazakhstan. Technogenic dispersion of heavy metals (HMs) causes adverse effects on living organisms and creates unfavorable conditions for the existence of humans, animals, and plants. The purpose of this study was to analyze the content of several HMs in samples of soil, horse feed (hay, mixed feed, and bran), mare’s milk, and manure to assess bioaccumulation and possible adverse effects on the bodies of horses. An additional purpose was to identify areas with acceptable conditions for obtaining environmentally safe horse breeding products in the agricultural zones of the Almaty region, Kazakhstan.Materials and Methods:Samples were obtained from two farms in the Almaty region in 2020 (spring, summer, and autumn). In total, 72 soil samples were analyzed, which were taken from the upper humus horizon to the depth of the arable layer. Eighty-six samples were taken from the feed of horses. Green feed was represented by perennial and annual grasses (alsike clover, Medicago sativa, sweet yellow clover, as well as pea and oat mix). Barley and wheat bran stored in the warehouses of the farm were sampled for the research as feed supplements. The mixed feed comprised components such as maize and sunflower. In addition, 46 samples of mare’s milk and 28 samples of horse manure were collected. The HM analysis was performed in the laboratory of the Kazakh-Japanese Innovation Center. The residual amounts of HMs were determined using an absorption spectrometer with a voltammetric analyzer. The content of cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) in all the studied samples of soil, feed, mare’s milk, and manure did not exceed the threshold limit values (TLVs), suggesting that the intake of these toxic elements into the human body with food was low.Results:The average Cd concentration was in the range of 0.29-0.31 mg/kg in soil samples and in the range of 0.20-0.27 mg/kg in feed samples. In milk, the Cd concentration varied from 0.01 to 0.02 mg/L and was lower in summer and higher in fall. The total average Cd content in horse manure was 0.1844 mg/kg. The concentration of Pb in soil samples ranged from 1.09 to 1.30 mg/kg with the lowest value in spring and the highest in fall. In the feed, the concentration of Pb varied from 0.14 to 0.76 mg/kg and in milk from 0.03 to 0.15 mg/L. The average concentrations of Hg and As in soil samples averaged 0.022 and 0.019 mg/kg, respectively, and were within the TLVs.Conclusion:In the study areas, the calculated transition rates in the soil–feed–milk–manure system revealed that the greatest transition of HMs was observed for Pb and Cd, and a smaller migration was observed for Hg and As. The tendency of accumulation of trace elements continued in the feed.

Impact of Al2O3 and Dy2O3 Substitution on the Physical, Structural, and Radiation Shielding Properties of Li2O-B2O3 Glass System

A new series of lithium-borate glass systems (23Li2O-72B2O3 in mol%) were synthesized with the substitution of Al2O3 (5 mol.%) as a modifier and doped with 0.3 and 0.5 mol% of Dy2O3. Four series of glasses (S1, S2, S3 and S4) were synthesized via the conventional melt-quenching technique and characterized by using UV-Visible-NIR absorption spectrometer and Fourier transform infrared (FTIR) spectroscopy. The current investigation gives further insight on the structural and optical properties of the samples. The diffraction spectrum obtained from the X-ray Diffraction (XRD) analysis shows no typical peaks in the glass system, which indicates its amorphous phase. The optical properties of Al3+ and Dy3+ ions were evaluated and found that there is a pivot effect for the addition of Al2O3 and Dy2O3 for the glass system. Notably, the sample S2 shows different behaviours for physical, structural, and optical properties compared with other prepared glass samples that can be attributed to the increment of Al2O3. Besides, the physical and ionizing shielding features were investigated for current glass samples. The radiation shielding properties were examined within the energy range of 0.015 until 15 MeV. The sample S4 has the optimum radiation shielding features as a result of the addition of Dy2O3. Hence, the composition attributes a new glass system that can be used in various applications such as radiation dosimeter and photon shielding materials.

Quantitative Determination of Airborne Redox-Active Compounds Based on Heating-Induced Reduction of Gold Nanoparticles.

Airborne redox-active compounds (ARC) account for a substantial fraction of atmospheric aerosols and play a vital role in chemical processes that influence global climate and human and ecological health. With the exception of the determination of total organic carbon by the expensive total organic carbon (TOC) analyzer, there is currently no easy-to-use method to quantify ARC. Here, we designed a method to detect the concentration of ARC by using the thermal-induced reduction and colorimetric behaviors of gold nanoparticles (AuNPs), in which the humic substances (HS) was used as a standard model of ARC to calculate the HS-equivalent concentration of ARC. Distinguished from the conventional complex methods, e.g., TOC analysis, the proposed approach measured localized surface plasmon resonance absorption of AuNPs and the target ARC concentration can be either directly quantified by the absorption spectrometer or qualitatively evaluated by the naked eyes. By using the absorption spectrometer, a limit of detection of 0.005 ppm by our AuNP sensor was achieved. To validate this sensing technique, aerosol samples collected from Basel (suburban), Bern (urban), and Rigi mountain (rural and high-altitude) sites in Switzerland were further investigated through the TOC combustion method. The results thereby substantiated that our plasmonic absorption-based AuNP sensor upholds a great promise for fast, cost-efficient total ARC detection and air quality assessment.

Direct Formulation of Bipropellant Thruster Performance for Quantitative Cold-Flow Diagnostic

We present a straightforward formulation predicting the characteristic velocity and specific impulse for bipropellant thrusters as a direct function of injection conditions, propellant combination, and nozzle expansion ratio. The theoretical formulation deduces a framework for a quantitative noncombustion test or cold-flow test to predict the performance indices. We simply employ water and dyed water as simulant liquids and then measure the local ratios of mixture and flow rate using an absorbance spectrometer. Density ratio mismatch between hypergolic propellants and water can be reasonably convertible. Combined with chemical equilibrium analysis, we obtain characteristic velocity and specific impulse across wide injection mixture ratios. The validity of the quantitative water-flow diagnostic is evidenced by comparing the results with those of corresponding combustion tests using nitrogen tetroxide and monomethylhydrazine as the propellants under several injector unlike-doublet and triplet configurations, showing that the mixing states of bipropellant thrusters under combustion can be reproduced using the water-flow diagnostic.

Photoinduced charge-separated molecular probe for ultrasensitive spectrum analysis and rapid colorimetric detection of platinum ions

Increased utilization of platinum ions in chemicals and drugs escalates environmental pollution and toxicity associated with Pt ions. However, current analysis and detection strategies of Pt ions display limited sensitivity due to the similar inert metal nature of platinum to gold. Herein, a photoinduced charge-separated molecule (MTPA)2Ab was synthesized as a probe for enhanced sensitive selection of Pt ions. Long-lived charge-separated states generated upon exposure to 365 nm light lead to a stable complex between (MTPA)2Ab and PtCl2/PtCl4 with highly-selectivity via sequential photoinduced electron transfers. Owing to the linear relationship of complex characteristic absorption and fluorescence emission intensities to Pt2+/Pt4+ concentrations, ultrasensitive spectrum analysis of Pt ions is achieved with a detection limit of 14.2 nM (2.8 ppb) for Pt2+ and 12.6 nM (2.5 ppb) for Pt4+ by an absorption spectrometer and 9.8 nM (1.9 ppb) for Pt ions (Pt2+/Pt4+) by a fluorescence spectrometer, far less than the reported values. Furthermore, a portable test box is developed based on (MTPA)2Ab test strips due to distinguishable color change with Pt2+/Pt4+ concentrations for rapid colorimetric detection of Pt ions. The results highlight the promise of photoinduced charge-separated molecular probe in ultrasensitive and rapid detection of Pt ions to overcome current limitations of detection strategies.

Anti-solvent mixture-mediated reduction of photocurrent hysteresis in high-impurity perovskite precursor based MAPbI3 solar cells

High-impurity precursor based CH3NH3PbI3 (MAPbI3) perovskite thin films are fabricated by using the one-step spin-coating method with an anti-solvent mixture-mediated nucleation (ASMEN) process under various dropping times. The structural, optical and excitonic properties of the resultant perovskite thin films are characterized through the X-ray diffractometer, absorbance spectrometer, photoluminescence spectrometer and Raman scattering spectrometer. The experimental results show that the dropping time and the use of 10% dicloromethane (DCM) in the ASMEN process strongly influences the formation of point defects in the resultant MAPbI3 thin film, which dominates the current-hysteresis behavior in the current density-voltage curves of solar cells. In addition, this investigation helps further understand the effects of toluene/DCM anti-solvent mixture on the formation of point defect-free MAPbI3 thin films.

Total Integration of the Sample Injection, Microdroplet Reaction, Phase Separation, Real‐Time Optical Detection, and Recovery of Diverse Silver–Gold Bimetallic Nanoalloys in a Continuous Process

AbstractMicrofluidic droplet generators have garnered great attention due to the uniformity, high‐throughput capability, and facile experimental setup. To maximize the potentials of droplet technology as a chemical/biological nanoliter‐scale reactor, the downstream processes such as separation of the aqueous and oil phase, real‐time monitoring of the products formed in droplets, and the final product recovery from the droplets is necessary. In this study, the droplet is utilized as a chemical reactor to synthesize a variety of Ag and Au bimetallic nanoalloys in a fully integrated microsystem including sample injection, a T‐junction droplet generator, droplet reaction, water–oil phase separation, real‐time UV–vis absorbance detection, and product recovery. The flow rate of the Ag nanoparticle (NP) solution and the HAuCl4 solution was tuned to generate different molar ratios of Ag and Au components. The in‐line UV–vis absorbance spectrometer displays a peak shift of the Ag/Au bimetallic alloys depending on the molar ratio of Ag/Au in the continuous process, enabling to judge the kind of the Ag/Au alloys in situ and collect a variety of Ag/Au nanoalloys. Thus, the desired nanomaterials can be obtained with minimal trial and error, saving time and cost.

The effect of activated carbon additives on lead sulphide thin film for solar cell applications

A photovoltaic device with an efficiency that could break the theoretical limit, exceeding ~60% is the focus in the research field in recent years. The efficiency of three important processes in a photovoltaic device need to be ensured to materialize the goal i.e., electron excitations, injections and regenerations. A multiple exciton generation (MEG) mechanism has been proven to increase the photovoltaic conversion efficiency - achievable via usage of small size lead chalcogenides as main light absorber of the photovoltaic device. An efficient electron injection in an excitonic solar cell could be achieved upon fulfilment of the following factors i.e., (i) LUMOfluorophore>CBphotoelectrode, and (ii) small offset between the LUMOfluorophore and CBphotoelectrode. The opto-electronic properties of lead chalcogenide are tuneable based on its size and morphology. Therefore, a synthesis method that could control the size and morphology of the yielded lead chalcogenide plays an important role. This research investigated the effect of additional activated carbon (AC) to the yielded PbS using vacuum thermal evaporator method. The PbS thin films were fabricated with addition of AC with different surface areas i.e., 80 m2/g, 650 m2/g and 1560 m2/g using thermal evaporator at vacuum pressure of 1.0 × 10−5 Torr. The surface area of the ACs was determined using Micromeritics ASAP 2020 BET (Brunauer-Emmett-Teller). The morphology, elemental analysis, crystal structure, opto-electronic, electron injection efficiency and electrical conductivity of the PbS thin film was characterized using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Spectrometer (EDX), X-Ray Diffractometer (XRD), absorption spectrometer, photoluminescence spectrometer (PL), and Bridge Technology 4-point probes (4PP) respectively. The excited and ground states of the PbS, and redox potential of ionLic PMII electrolyte were determined using quantum chemical calculations at b3lyp/lanl2dz level of theory. Three important observations have been made i.e., (i) addition of AC with the PbS reactants affects the yielded morphology of PbS thin film, (ii) bare PbS/TiO2 device structure offers electron injection efficiency as high as 97% from the PbS to TiO2, and (iii) the bare PbS/TiO2 device structure would offer maximum VOC of ca. 1.7 V, however need to be paired with an electrolyte that possess oxidation potential of ca. −6.5 eV.

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Abstract. The development of fast-response analysers for the measurement of nitrous oxide (N2O) has resulted in exciting opportunities for new experimental techniques beyond commonly used static chambers and gas chromatography (GC) analysis. For example, quantum cascade laser (QCL) absorption spectrometers are now being used with eddy covariance (EC) or automated chambers. However, using a field-based QCL EC system to also quantify N2O concentrations in gas samples taken from static chambers has not yet been explored. Gas samples from static chambers are often analysed by GC, a method that requires labour and time-consuming procedures off-site. Here, we developed a novel field-based injection technique that allowed the use of a single QCL for (1) micrometeorological EC and (2) immediate manual injection of headspace samples taken from static chambers. To test this approach across a range of low to high N2O concentrations and fluxes, we applied ammonium nitrate (AN) at 0, 300, 600 and 900 kg N ha−1 (AN0, AN300, AN600, AN900) to plots on a pasture soil. After analysis, calculated N2O fluxes from QCL (FN2O_QCL) were compared with fluxes determined by a standard method, i.e. laboratory-based GC (FN2O_GC). Subsequently, the comparability of QCL and GC data was tested using orthogonal regression, Bland–Altman and bioequivalence statistics. For AN-treated plots, mean cumulative N2O emissions across the 7 d campaign were 0.97 (AN300), 1.26 (AN600) and 2.00 kg N2O-N ha−1 (AN900) for FN2O_QCL and 0.99 (AN300), 1.31 (AN600) and 2.03 kg N2O-N ha−1 (AN900) for FN2O_GC. These FN2O_QCL and FN2O_GC were highly correlated (r=0.996, n=81) based on orthogonal regression, in agreement following the Bland–Altman approach (i.e. within ±1.96 standard deviation of the mean difference) and shown to be for all intents and purposes the same (i.e. equivalent). The FN2O_QCL and FN2O_GC derived under near-zero flux conditions (AN0) were weakly correlated (r=0.306, n=27) and not found to agree or to be equivalent. This was likely caused by the calculation of small, but apparent positive and negative, FN2O when in fact the actual flux was below the detection limit of static chambers. Our study demonstrated (1) that the capability of using one QCL to measure N2O at different scales, including manual injections, offers great potential to advance field measurements of N2O (and other greenhouse gases) in the future and (2) that suitable statistics have to be adopted when formally assessing the agreement and difference (not only the correlation) between two methods of measurement.

Investigation of the layer-dependent optical properties of ultrathin BiOI by spectroscopic ellipsometry

Layered semiconductor BiOI has gained considerable interests in the field of optoelectronics, but the basic knowledge of its optical and dielectric properties is still lack of a full investigation. Here, by using spectroscopic ellipsometry (SE), the complex refractive indexes and dielectric constants of ultrathin BiOI films over a wide spectral range are measured for the first time. The ellipsometric angle Δ is found to be linear with the layer number of BiOI, suggesting that SE could be a facile way to estimate the thickness of 2D BiOI. The optical properties of BiOI show a distinct layer-dependent feature, and the bandgap values of 2D BiOI increase from 1.99 to 2.33 eV with decreasing thickness. Further, the results from absorption spectrometer also show a blue shift of bandgap energy with decreasing thickness. Our work provides valuable data about the optical properties of ultrathin BiOI, and can shed a light on the exploration of original applications based on 2D BiOI.

Water Soluble Silicon Quantum Dots Grafted with Amoxicillin as a Drug Delivery System.

Water soluble silicon quantum dots (Si QDs) are prepared and used for the measurement of the efficiency for the controlled release drug delivery. Amoxicillin, antibiotics, is covalently grafted with Si QDs through a surface derivatization reaction. Si QDs are embedded in hydrogel polymer. The release of amoxicillin has been measured by using Ultra violet-visible (UV-vis) absorption spectrometer. Amoxicillin-embedded hydrogels exhibit a burst release for 1 h, however covalently loaded Amoxi-Si QDs hydrogel composite exhibited very slow release. Absorption analysis reveals that the Si QDs exhibits a great potential candidate for controlled release of drug. The controlled drugrelease profiles depend on the hydrolysis of amoxicillin from the surface of Si QDs.

Synthesis and up-conversion properties of Er3+ doped ZnTiO3-Zn2TiO4 composite phosphor

The conventional solid state reaction method was used to prepare Er3+ activated ZnTiO3-Zn2TiO4 composite phosphor. The structure, particle morphology, absorption, and photoluminescent properties were analyzed using x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis-NIR absorption spectrometer, and photoluminescence (PL) spectroscopy, respectively. The XRD confirmed the crystallization of mixed hexagonal ZnTiO3 and cubic spinel Zn2TiO4 phases. The SEM data showed that the prepared phosphor was made up of faceted hexagons. Furthermore, the phosphor was excited in the near-infrared (NIR) region using a laser diode with a wavelength of 980 nm, and the corresponding up-conversion emission lines were observed in the visible range at 543, 553, and 650–670 nm, associated with the 2H11/2 → 4I15/2, 4S1/2 → 4I15/2, and 4F9/2 → 4I15/2 transitions of Er3+ ions, respectively. The interaction mechanisms involved in the up-conversion process of ZnTiO3-Zn2TiO4:Er3+ phosphor are discussed with the help of an energy-level schematic diagram, and the number of the photons involved in the up-conversion luminescence process was estimated.

Manganese–Fluorouracil Metallodrug Nanotheranostic for MRI-Correlated Drug Release and Enhanced Chemoradiotherapy

For cancer therapy, drug delivery systems are often limited by insufficient drug loading capacity, which usually results in systemic toxicity and heavy metabolic burden to excrete the carriers. Her...