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In situ Determination of Nitrate and Hydrogen Sulfide in the Baltic Sea Using an Ultraviolet Spectrophotometer
摘要： Evaluating the health status of marine ecosystems becomes ever increasingly important especially against the backdrop of rising pressures from human activities. This is true especially for coastal seas such as the Baltic Sea that is surrounded by highly industrialized countries. Nutrients and pollutants such as nitrate and hydrogen sulfide, which have a major impact on ecosystem functioning, are two of several indicators for assessing the status of natural waters, and therefore key environmental of considerable interest. The frequency and the spatial coverage of the nitrate and hydrogen sulfide measurements are currently limited by the cost of the laboratory analysis and personnel. Optical in situ sensors can help to overcome this challenge by allowing reagentless and fast detection of dissolved chemical species. A chemical-free optical sensor has been used for direct and simultaneous measurements of both key parameters, and the results were compared with traditional methods. The data were collected during an observational program conducted in the Baltic Sea in February 2018. We used the OPUS UV spectral sensor, which was deployed for the first time in coastal waters, in combination with a deep-sea telemetry system to enable near-real time measurements during CTD profiling. Data processing was carried out using a multiple linear regression procedure. Measurements from both OPUS and on-board analysis were in good agreement. The results showed, that in situ UV-VIS spectrophotometry provides the capability to determine the concentration distributions of nitrate and hydrogen sulfide in the brackish waters of the Baltic Sea.
关键词： sulfide,Baltic Sea,monitoring,hypoxia,nutrients,UV-VIS spectrophotometry
更新于2025-09-23 15:22:29
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Synthesis and Characterization of Aluminum Nanoparticles Prepared in Vinegar Using a Pulsed Laser Ablation Technique
摘要： The second harmonic wavelength of a neodymium-doped yttrium-aluminum-garnet (Nd-YAG) laser (λ = 532 nm) was used in a pulsed laser ablation technique (PLAL) to synthesize aluminum nanoparticles suspended in white vinegar from an aluminum target. The nanoparticles were characterized by HRTEM and UV-Vis spectrophotometry. They were found to range in size between 2 and 50 nm in diameter, with an average diameter of 12 ± 9 nm. The nanoparticles had a maximum absorption peak at 237 nm and were found to exhibit a core-shell structure with an Al core coated by a thin layer of an amorphous material which could be attributed to amorphous carbon. HRTEM results revealed that the small nanoparticles (<20 nm) had an fcc phase of aluminum crystalline structure, where the larger particles represented alumina (γ-Al2O3) nanoparticles. Such observation suggests that the use of white vinegar as an ablation medium could facilitate the synthesis of aluminum nanoparticles with minimal evidence of the existence of aluminum oxide nanoparticles in the resultant suspension.
关键词： pulsed laser ablation in liquid (PLAL),UV-Vis spectrophotometry,white vinegar,HRTEM,Aluminum nanoparticles
更新于2025-09-19 17:13:59
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Deposition of Cu2ZnSnS4 films by doctor blade printing using a one-step microwave heated ink as an absorber layer for solar cells
摘要： Kesterite (Cu2ZnSnS4, CZTS) semiconductors are known as the most suitable compounds for the synthesis of absorber layers. These compounds are used in solar cells due to their high solar energy absorption coe?cient and ideal band gap. In the present work, the microwave-assisted process and doctor blade printing were used to prepare Cu2ZnSnS4 ?lms. To this aim, ink solution was used, which consisted of copper, zinc acetate, tin chloride and thiourea as copper, zinc, tin and sulfur precursors, respectively. Ethylene glycol was used as a non-toxic solvent. The CZTS ink was prepared using microwave heating for 10 min. The CZTS layers were printed on soda lime silica glass substrates and heat treated at 150, 200, 250, 300, and 350°C. The microstructure, phase analysis, morphology, optical properties, and absorption ratio of the samples were evaluated using X-ray di?raction analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, transmittance spectroscopy, ?eld emission scanning electron microscopy (FESEM), energy dispersive X-ray, and UV–Vis spectrophotometry. The formation of the Kesterite structure was con?rmed using X-ray di?raction and Raman spectroscopy. The FESEM micrographs and DLS (dynamic light scattering) revealed that the ?lms contained equated grains with the diameter range of 350–650 nm. According to the X-ray analysis and Raman spectrum, the highest crystallization and purity of the Kesterite phase as well as the best microstructure property and morphology (smooth spherical particles with good adhesion) of the CZTS ?lms were found in the synthesized specimen at 300°C. The band gap of the samples was measured to be about 1.5 eV using UV–Vis spectrophotometry.
关键词： Microwave heating process,UV–Vis spectrophotometry,Solar cell,CZTS ?lm
更新于2025-09-16 10:30:52
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Personalized nanomedicine: a rapid, sensitive, and selective UV–vis spectrophotometry method for the quantification of nanostructured PEG-asparaginase activity in children’s plasma
摘要： PEGylated asparaginase (PEG-ASNase), which hydrolyzes asparagine to ammonia and aspartic acid, is an effective nanostructured antitumor agent for acute lymphoblastic leukemia (ALL). In order to monitor the activity of PEG-ASNase in plasma and design an individualization project, a rapid and sensitive method to determine PEG-ASNase activity in plasma using ultraviolet–visible spectrophotometry was established. Methods: PEG-ASNase is commonly used in acute lymphoblastic leukemia. With Nessler’s reagent as the chromogenic reagent of ammonia, a stable yellow complex was produced. The units of enzyme activity were defined as micromoles of ammonia released per minute. Results: Calibration curves fitted by plotting the OD at 450 nm of the Nessler product vs concentration were linear in the range of 27.8–1,111.0 IU/L with r2=0.999. The lower limit of quantification for PEG-ASNase activity in human plasma was 20 IU/L with good accuracy and precision. The intra- and interday precision (relative standard deviation) values were below 10% and accuracy ranged from 90% to 110% at all quality control levels. Analytical recoveries were determined between 90% and 110% for all quality control samples. Conclusion: This study proved that the Nessler method is well validated and can be successfully applied in the determination of plasma samples in the clinical setting for patients with ALL. It takes personalized nanomedicine to an entirely new level.
关键词： PEG-ASNase,plasma,ALL,enzyme activity,Nessler method,personalized nanomedicine,UV–vis spectrophotometry,Nessler’s reagent
更新于2025-09-09 09:28:46
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Dose response and stability of water equivalent PRESAGE <sup>?</sup> dosimeters for synchrotron radiation therapy dosimetry
摘要： This research investigated the dose response and post-irradiation stability of water-equivalent PRESAGE? dosimeters exposed to synchrotron radiation. Water-equivalent PRESAGE? dosimeters were irradiated up to 1000 Gy in a synchrotron x-ray beam with a mean energy of 95.3 keV. The change in optical density was measured using UV/visible spectrophotometry pre- and post-irradiation using a wavelength of 630 nm. Dose response was found to be approximately linear from 0–200 Gy with saturation occurring above 300 Gy. The post-irradiation stability was determined by measuring the change in optical density at 10, 30, 60, 180, 420 min and 7, 21 and 33 d post-irradiation for three groups of dosimeters stored at different temperatures. Each group had two dosimeters irradiated at 50, 100, 200 and 300 Gy and each group was stored at a different temperature following irradiation: room temperature (22 °C), 4 °C and ?18 °C. The optimal time for readout of the dosimeters varied with the post-irradiation storage temperature. The room temperature group had an optimal time-to-readout of 10 min for maximum signal before fading, while the 4 °C group was reasonably stable from 90 min to 1 week. The ?18 °C group showed the least amount of ongoing post-irradiation development and fading with an optimal readout window from 30 min to 21 d. The intra-batch variation between the mean of each temperature control group was 4.2% at 10 min post-irradiation.
关键词： PRESAGE? dosimeter,synchrotron radiation therapy,UV/Vis spectrophotometry
更新于2025-09-09 09:28:46
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Preparation of water-soluble asphalt carbon dots and hyperchromic effect to Cr (VI)
摘要： Water-soluble asphalt carbon dots（W-CDs）was prepared from medium - temperature coal tar pitch as raw material, via mixed acid oxidation，alkali solubilization and acid precipitation method. It was observed that as-prepared W-CDs were irregular particles with good water dispersibility and the particle size was controlled by the pH of the acid precipitation solution by a polarizing microscope . Infrared spectroscopy confirmed that the surface of the W-CDs was functionalized by hydrophilic and color-promoting functional groups, which had good water solubility; the thermal weight loss proved to be good thermal stability below 200°C; the fluorescence spectrum proved that the fluorescence emission peak position of the carbon dots appears red shift with increase of excitation wavelength, with fluorescence conversion property, and its emission light intensity decreases, belonging to non-resonant fluorescence type of direct jump fluorescence; UV spectrum proves that the addition of W-CDs can be chromium (VI) CrO4 2- content The detection limit was increased from milligram to microgram; the molar absorptivity of CrO4 2- was increased by 4 times. The experimentally optimized W-CDs-ultraviolet-viscometry method for measuring CrO4 2- conditions: W-CDs to chromium ratio of 8:2, pH of 8, hexamethylenetetramine as a surfactant, and the solution was allowed to stand at room temperature for 45 min.
关键词： hyperchromic effect,Cr (Ⅵ),UV-vis spectrophotometry,Water-soluble asphalt carbon dots
更新于2025-09-04 15:30:14
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Detection in UV-visible spectrophotometry: Detectors, detection systems, and detection strategies
摘要： A compilation of the new developments in terms of detection, detections systems and detection strategies in Ultraviolet-Visible (UV-Vis) spectrophotometry is presented and discussed. It is shown that this evolution has promoted the use of UV-Vis spectrophotometry as a simple, sensitive, reliable, and low cost technique, that allows the determination of very low concentrations of compounds, and the use of very small amounts of samples. The versatility, and the portability of the developed equipment and strategies, have also contributed for the continuous use of UV-Vis spectrophotometry, over the years. By the examples of its use in diverse fields such as agriculture, food, clinical, pharmaceutical, and environmental is highly expectable that detection in UV-Vis spectrophotometry, continues to evolve and to promote this kind of applications.
关键词： Organic compounds,Quantitative analysis,Detectors,Qualitative analysis,UV-vis spectrophotometry,Detection
更新于2025-09-04 15:30:14