This research investigates organic photovoltaic (OPV) structures using time-correlated single photon counting (TCSPC) to study time-resolved fluorescence dynamics under low injection conditions. A picosecond laser diode with a wavelength of 650 nm and a single photon avalanche diode (SPAD) are applied for excitation and detection. The measurements are performed at an irradiance of 0.011 W/cm2 (1.2 & times; 108 photons/pulse) which is sufficiently low to avoid damaging the sample. Decay characteristics are analyzed using iterative reconvolution. The samples include various absorber species and structural configurations, revealing fluorescence decay components as short as 30-500 ps. Such rapid dynamics can only be detected using conventional photodiode-based setups at much higher excitation levels. The findings indicate that while absorption spectra vary with structural properties like layer thickness, decay times are primarily determined by the absorber material. TCSPC measurements thus provide deeper insights into the recombination dynamics of organic semiconductors.

We functionalized fluorescent nanodiamonds of various sizes using a thiourea-based thiolation reaction to tailor their surface chemistry for biological and quantum technological applications. Spectroscopic analyses revealed that this reaction generates a complex mixture of sulfur- and nitrogen-containing groups, arising from the reaction of thiourea with surface functional groups and from oxidative cyclization. Since the charge stability of negatively charged nitrogen-vacancy (NV⁻) centers is strongly influenced by the near-surface electronic structure, surface modifications that enhance this stability—while preserving colloidal dispersibility and enabling further functionalization—are essential for quantum sensing applications. We show that the surface chemistry produced through the reaction of nanodiamonds with thiourea increases electron availability and favors the stabilization of the NV⁻ charge state. These results highlight the potential of thiourea-derived surface modification as an effective route to improve the quantum performance of nanodiamonds.

In this study, we implement thiol termination on the surface of few-nanometer-sized silicon carbide (SiC) nanoparticles (NPs) to enable further applications, such as fluorescent biomarkers. Various spectroscopic techniques are employed to monitor the effectiveness of the surface treatment. A thiol-Michael addition reaction is performed by conjugating 4-arm PEGmaleimide molecules to the thiol groups of SiC NPs, further demonstrating the reactivity of thiol-terminated SiC NPs, which also acts as a protection layer against oxidation. These fluorescent thiolated SiC NPs, both with and without conjugated molecules, are directly applicable as bioinert probes. Since SiC NPs can potentially host room-temperature fluorescent defect quantum bits, our results are an important step to realize a bioinert, ultrasmall quantum sensor bioagents, which may open new avenues in biotechnology. © 2001 Elsevier Science. All rights reserved.

In this study, we implement thiol termination on the surface of few-nanometer-sized silicon carbide (SiC) nanoparticles (NPs) to enable further applications, such as fluorescent biomarkers. Various spectroscopic techniques are employed to monitor the effectiveness of the surface treatment. Additionally, a thiol-Michael addition reaction is performed by conjugating 4-arm PEG-maleimide molecules to the thiol groups of SiC NPs, further demonstrating the reactivity of thiol-terminated SiC NPs. These thiolated SiC NPs, both with and without conjugated molecules, open new avenues in biotechnology.

This study evaluated the physiological responses of Eucalyptus urophylla x Eucalyptus grandis under varying water stress levels and their recovery post-rehydration. Plants were exposed to control, light (LS), and moderate (MS) water stress treatments in an open area, with continuous monitoring of meteorological conditions. Physiological parameters, including net photosynthesis, stomatal conductance, transpiration, and the Crop Water Stress Index (CWSI), were assessed. Mini-lysimeters measured cumulative plant transpiration. Results showed that predawn leaf water potential (4'pd) declined by approximately 196% under LS and 599% under MS compared to the control (-0.2), reflecting significant stress, alongside an increased CWSI due to stomatal closure and higher leaf temperatures. Water stress significantly reduced gas exchange variables, notably photosynthesis, which showed quicker recovery after rehydration compared to transpiration and stomatal conductance. Changes in the photochemical fluorescence parameter qP(3), defined as the coefficient of photochemical quenching measured at the third saturation pulse during fluorescence induction, reflected adjustments in photochemical activity. Five days post-rehydration, plants exhibited partial recovery, with photosynthesis regaining more rapidly than other gas exchange processes. Overall, the study underscores that water stress heavily impairs in E. urophylla x E. grandis physiological processes, though photosynthesis recovers more readily than transpiration and stomatal conductance, depending on stress severity.

This paper presents a novel high-resolution and rapid (50 ms) UV imaging system, which was used for at-line, non-destructive API content determination of tablets. For the experiments, amlodipine and valsartan were selected as two colourless APIs with different UV induced fluorescent properties according to the measured solid fluorescent spectra. Images were captured with a LED-based UV illumination (385-395 nm) of tablets containing amlodipine or valsartan and common tableting excipients. Blue or green colour components from the RGB colour space were extracted from the images and used as an input dataset to execute API content prediction with artificial neural networks. The traditional destructive, solution-based transmission UV measurement was applied as reference method. After the optimization of the number of hidden layer neurons it was found that the relative error of the content prediction was 4.41 % and 3.98 % in the case of amlodipine and valsartan containing tablets respectively. The results open the possibility to use the proposed UV imaging-based system as a rapid, in-line tool for 100 % API content screening in order to greatly improve pharmaceutical quality control and process understanding.

The study aimed to develop a measurement apparatus for in vivo chlorophyll-a (Chl-a) fluorescence decay measurements of plants by means of time correlated single photon counting. In this approach, sub-nanosecond laser pulses with a repetition rate of 10 MHz are applied to excite the sample, followed by the analysis of arrival times of the emitted fluorescence photons. Photon statistics are generated by iteratively fitting the sum of two exponential functions. The tool was tested on both plastid and in vivo leaf samples of Savoy cabbage (Brassica oleracea var. sabauda) with 3-4 subsequent leaves giving a complete sample coverage starting from the outermost. The Chl-a fluorescence lifetime exhibited a gradual increase in both the isolated plastid suspensions and the in vivo leaf samples towards the innermost leaf layers explained by an increase of natural absence of light (etiolation syndrome). Furthermore, cadmium stress and iron deficiency were investigated on treated sugar beet (Beta vulgaris) samples in vivo using TCSPS measurements. The reduced fluorescence quenching resulted in an increased fluorescence lifetime. Finally, a long-term (10 week) testing of the setup was carried out on Chl-retaining resurrection Haberlea rhodopensis plants protecting themselves by an elevated non-photochemical quenching yielding a decrease of fluorescence lifetime during their desiccation.

The occurrence of the market-leading glyphosate active ingredient in surface waters is a globally observed phenomenon. Although co-formulants in pesticide formulations were considered inactive components from the aspects of the required main biological effect of the pesticide, several studies have proven the high individual toxicity of formulating agents, as well as the enhanced combined toxicity of the active ingredients and other components. Since the majority of active ingredients are present in the form of chemical mixtures in our environment, the possible combined toxicity between active ingredients and co-formulants is particularly important. To assess the individual and combined phytotoxicity of the components, glyphosate was tested in the form of pure active ingredient (glyphosate isopropylammonium salt) and herbicide formulations (Roundup Classic and Medallon Premium) formulated with a mixture of polyethoxylated tallow amines (POEA) or alkyl polyglucosides (APG), respectively. The order of acute toxicity was as follows for Roundup Classic: glyphosate < herbicide formulation < POEA. However, the following order was demonstrated for Medallon Premium: herbicide formulation < glyphosate < APG. Increased photosynthetic activity was detected after the exposure to the formulation (1.5–5.8 mg glyphosate/L and 0.5–2.2 mg POEA/L) and its components individually (glyphosate: 13–27.2 mg/L, POEA: 0.6–4.8 mg/L), which indicates hormetic effects. However, decreased photosynthetic activity was detected at higher concentrations of POEA (19.2 mg/L) and Roundup Classic (11.6–50.6 mg glyphosate/L). Differences were demonstrated in the sensitivity of the selected algae species and, in addition to the individual and combined toxicity of the components presented in the glyphosate-based herbicides. Both of the observed inhibitory and stimulating effects can adversely affect the aquatic ecosystems and water quality of surface waters.

The environmental load by isoxaflutole and its formulated herbicide products has increasingly become apparent because, after the ban of atrazine, isoxaflutole has become its replacement active ingredient (a.i.). Obtaining information regarding the fate of this a.i. in environmental matrices and its ecotoxicological effects on aquatic organisms is essential for the risk assessment of the herbicide. In this study, the effects of Merlin Flexx- and Merlin WG75 formulated isoxaflutole-based herbicide products and two selected additives (cyprosulfamide safener and 1,2-benzisothiazol-3(2H)-one antimicrobial agent) were investigated on Raphidocelis subcapitata in growth inhibition assays. In ecotoxicological tests, two conventional (optical density and chlorophyll-a content) and two induced fluorescence-based (Fv*/Fp: efficiency of the photosystem PSII and Rfd* changes in the observed ratio of fluorescence decrease) endpoints were determined by UV-spectrophotometer and by our FluoroMeter Module, respectively. Furthermore, dissipation of isoxaflutole alone and in its formulated products was examined by an HPLC-UV method. In ecotoxicological assays, the fluorescence-based Rfd* was observed as the most sensitive endpoint. In this study, the effects of the safener cyprosulfamide and the antimicrobial agent 1,2-benzisothiazol-3(2H)-one on R. subcapitata is firstly reported. The results indicated that the isoxaflutole-equivalent toxicity of the mixture of the isoxaflutole–safener–antimicrobial agent triggered lower toxicity (EC50 = 2.81 ± 0.22 mg/L) compared to the individual effect of the a.i. (EC50 = 0.02 ± 0.00 mg/L). The Merlin Flexx formulation (EC50 = 27.04 ± 1.41 mg/L) was found to be approximately 50-fold less toxic than Merlin WG75, which can be explained by the different chemical characteristics and quantity of additives in them. The additives influenced the dissipation of the a.i. in Z8 medium, as the DT50 value decreased by approximately 1.2- and 3.5-fold under light and dark conditions, respectively.

The effect of laser irradiation in the energy range from 20 mW to 200 mW was investigated in 109 nm thick Fe _51 Rh _49 film deposited on an MgO (100) substrate. The initial, A1 structure with fully paramagnetic magnetic ordering was achieved after irradiating the samples with 120 keV Ne ^+ ions with a fluence of 1 × 10 ^16 ion cm ^−2 , as it was confirmed by conversion-electron Mössbauer spectroscopy. At higher powers physical damage of the layer was observed, while in the lowest power case, magnetic force microscopy revealed a well-defined magnetic structure reflecting the laser irradiation pattern. The presented results have the potential to be employed for laser ablation or allows the fabrication of arbitrary ferromagnetic pattern within a homogeneous paramagnetic FeRh thin films.

Silicon carbide nanoparticles (SiC NPs) are promising inorganic molecular-sized fluorescent biomarkers. It is imperative to develop methods to functionalize SiC NPs for certain biological applications. One possible route is to form amino groups on the surface, which can be readily used to attach target biomolecules. Here, we report direct amino-termination of aqueous SiC NPs. We demonstrate the applicability of the amino-terminated SiC NPs by attaching bovine serum albumin as a model for functionalization. We monitor the optical properties of the SiC NPs in this process and find that the fluorescence intensity is very sensitive to surface termination. Our finding may have implications for a few nanometers sized SiC NPs containing paramagnetic color centers with optically read electron spins.

Introduction:Iron (Fe) is one of themost important cofactors in the photosynthetic apparatus, and its uptake by chloroplasts has also been associated with the operation of the photosynthetic electron transport chain during reduction-based plastidial Fe uptake. Therefore, plastidial Fe uptake was considered not to be operational in the absence of the photosynthetic activity. Nevertheless, Fe is also required for enzymatic functions unrelated to photosynthesis, highlighting the importance of Fe acquisition by non-photosynthetic plastids. Yet, it remains unclear how these plastids acquire Fe in the absence of photosynthetic function. Furthermore, plastids of etiolated tissues should already possess the ability to acquire Fe, since the biosynthesis of thylakoid membrane complexes requires a massive amount of readily available Fe. Thus, we aimed to investigate whether the reduction-based plastidial Fe uptake solely relies on the functioning photosynthetic apparatus.Methods:In our combined structure, iron content and transcript amount analysis studies, we used Savoy cabbage plant as a model, which develops natural etiolation in the inner leaves of the heads due to the shading of the outer leaf layers.Results:Foliar and plastidial Fe content of Savoy cabbage leaves decreased towards the inner leaf layers. The leaves of the innermost leaf layers proved to be etiolated, containing etioplasts that lacked the photosynthetic machinery and thus were photosynthetically inactive. However, we discovered that these etioplasts contained, and were able to take up, Fe. Although the relative transcript abundance of genes associated with plastidial Fe uptake and homeostasis decreased towards the inner leaf layers, both ferric chelate reductase FRO7 transcripts and activity were detected in the innermost leaf layer. Additionally, a significant NADP(H) pool and NAD(P)H dehydrogenase activity was detected in the etioplasts of the innermost leaf layer, indicating the presence of the reducing capacity that likely supports the reduction-based Fe uptake of etioplasts.Discussion:Based on these findings, the reduction-based plastidial Fe acquisition should not be considered exclusively dependent on the photosynthetic functions.

Our research group developed a novel nano-pitted (NP) TiO2 surface on grade 2 titanium that showed good mechanical, osteogenic, and antibacterial properties; however, it showed weak hydrophilicity. Our objective was to develop a surface treatment method to enhance the hydrophilicity of the NP TiO2 surface without the destruction of the nano-topography. The effects of dilute and concentrated orthophosphoric (H3PO4) and nitric acids were investigated on wettability using contact angle measurement. Optical profilometry and atomic force microscopy were used for surface roughness measurement. The chemical composition of the TiO2 surface and the oxidation state of Ti was investigated using X-ray photoelectron spectroscopy. The ccH3PO4 treatment significantly increased the wettability of the NP TiO2 surfaces (30°) compared to the untreated control (88°). The quantity of the absorbed phosphorus significantly increased following ccH3PO4 treatment compared to the control and caused the oxidation state of titanium to decrease (Ti4+ → Ti3+). Owing to its simplicity and robustness the presented surface treatment method may be utilized in the industrial-scale manufacturing of titanium implants.

Bevezetés: Világszerte egyre szélesebb körben alkalmazzák a cirkónium-dioxid kerámiákat monolitikus fogpótlásokanyagaként. A teljes kerámiarendszerek esetén a végleges restaurátum esztétikáját a kerámiaanyag színén túl olyantovábbi tényezők is befolyásolják, mint a csonkszín, a kerámia vastagsága és transzlucenciája, illetve a cement színeés rétegvastagsága.Célkitűzés: A Semmelweis Egyetem Fogpótlástani Klinikájának és a Budapesti Műszaki és GazdaságtudományiEgyetem Atomfizika Tanszékének közös in vitro kísérletének célja tanulmányozni, hogy a különböző árnyalatú és vastagságúmonolitikus cirkónium-dioxid kerámiák optikai tulajdonságait milyen módon befolyásolja a csonkszín és a cementszín.Anyag és módszer: Vizsgálatunkhoz kétféle árnyalatú (A2P1, WHITE), ötféle rétegvastagságú cirkónium-dioxid mintát(Erran Tech), háromféle próbacementet (Variolink Esthetic Try-In Paste, Ivoclar Vivadent), kilencféle csonkanyagot(hat VITA Simulate, három fémtartalmú csonkanyag) használtunk fel. Méréseinket a Budapesti Műszaki és GazdaságtudományiEgyetem Atomfizika Tanszékén lévő PerkinElmer LAMBDA 1050 UV/Vis/NIR spektrofotométerrel végeztükel. A színkülönbség (ΔE) számításához a CIEDE2000 képletet alkalmaztuk.Eredmények: 0,5 mm vastagságú A2P1-minták esetén az átlagos ΔE xΔE = 4,10 (σΔE = 2,91); 2,5 mm vastagság mellettxΔE = 1,88 (σΔE = 0,67). 0,5 mm vastagságú WHITE-minták esetén az átlagos ΔE xΔE = 6,40 (σΔE = 2,75); 2,5 mmvastagság mellett xΔE = 5,46 (σΔE = 0,79).Megbeszélés: A kutatás rámutatott arra, hogy a cirkónium-dioxid minták színezettsége és rétegvastagsága nagybanbefolyásolja a fedőképességet, illetve 1,5 mm kerámiavastagság mellett a próbacementek szignifikáns színeltérést okoznak.A színezetlen cirkónium-dioxidok színét kevésbé befolyásolja a csonkszín, különösen 1,5 mm rétegvastagság felett.Következtetés: Elszíneződött csonkok monolitikus cirkónium-dioxid fogpótlással való fedése esetén a rétegvastagságnövelésével esztétikusabb végeredményt tudunk elérni a vizsgált színezett cirkónium-dioxid alkalmazása mellett.

Project Aquafluosense was designed to develop prototypes for a modular fluorescence-based instrumental setup for in situ measurement of major water quality parameters. A fluorometer was developed for algal density estimation based on the fluorescent excitation of chlorophyll. The appropriate type of sample holder microplate was determined, along with the need for dark acclimation, prior to the measurements during the instrument’s development. Model species of green (Raphidocelis subcapitata) and blue-green alga (Microcystis aeruginosa) were applied in forms of pure monocultures and their mixtures, and improved analytical limits of detection were achieved (3.70 × 103 cell/mL and 1.13 × 105 for R. subcapitata and M. aeruginosa, respectively). The fluorescence-based determination of algal density was validated by conventional methods, such as cell counting in a Bürker chamber, optical density measurement, and chlorophyll extraction with ethanol. The signals obtained by the fluorometer correlated well with the conventional methods. Pearson r coefficients (applied where the correlation was linear) were ≥0.988 and Spearman ρ coefficients (applied where the correlation was not linear) were >0.976, indicating a strong and positive correlation. The applicability of the developed fluorometer was demonstrated in a growth inhibition ecotoxicity assay on R. subcapitata using the herbicide active ingredient isoxaflutole. During the assay, light intensity (continuous, 104.9 ± 14.9 µE/m2/s), temperature (22 ± 2 °C), pH of algal media (pH = 6–7 for Zehnder and Allen media, as well), and intensity of stirring (continuous, 100 rpm) were controlled. The results indicated that the FluoroMeter Module is applicable for screening algal toxicity: the observed ratio of fluorescence decrease determined by fluorescence induction provided significantly lower toxicity values (EC50: 0.015 ± 0.001 µg/mL) compared to values determined by the optical density (EC50: 0.034 ± 0.004 µg/mL) and chlorophyll a content (EC50: 0.033 ± 0.000 µg/mL).

An enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the quantitative analytical determination of the herbicide active ingredient glyphosate in environmental matrices (surface water, soil, and plant tissues). Glyphosate, as a ubiquitous agricultural pollutant, is a xenobiotic substance with exposure in aquatic and terrestrial ecosystems due its extremely high worldwide application rate. The immunoassay developed in Project Aquafluosense is part of a fluorescence-based instrumentation setup for the in situ determination of several characteristic water quality parameters. The 96-well microplate-based competitive immunoassay method applies fluorescence signal detection in the concentration range of 0–100 ng/mL glyphosate. Application of the fluorescent signal provides a limit of detection of 0.09 ng/mL, which is 2.5-fold lower than that obtained with a visual absorbance signal. Beside the improved limit of detection, determination by fluorescence provided a wider and steeper dynamic range for glyphosate detection. No matrix effect appeared for the undiluted surface water samples, while plant tissues and soil samples required dilution rates of 1:10 and 1:100, respectively. No cross-reaction was determined with the main metabolite of glyphosate, N-aminomethylphosphonic acid, and related compounds.

A színtestek (vagy plasztiszok) két burokmembránnal határolt és belső membránrendszerrel rendelkező sejtszervecskék, amelyek számos típusa található változatos formában és funkcióval a növények sejtjeiben [1]. Általánosságban a sejt felépítő jellegű (anabolikus), energia-befektetést igénylő anyagcsere-folyamataiban vesznek részt. A zöld növényekben hétféle színtestet szokás elkülöníteni. Ezek közül a legismertebb a fotoszintézis folyamatáért felelős zöld színtest (kloroplasztisz), amely belsejében helyezkedik el a belső burokmembrán befűződéséből kialakult, magányos membrán zsákokból (ún. tilakoidokból) és korongszerűen egymásra rétegződött tilakoidokból álló komplex membránrendszer, amelybe a fotoszintetikus apparátus beágyazódik. Ennek fontos elemei a fénnyel kölcsönható pigment-molekulákat tartalmazó ún. fotorendszerek, valamint a fotoszintézishez szükséges enzimek. A fotorendszeren belül a fény energiájának összegyűjtését végző fénybegyűjtő, valamint továbbításáért felelős antenna molekulákat képező klorofill-molekulák tömegei veszik körbe a reakcióközpontot, ami gerjesztett elektron formájában csapdázza az energiát a további fotokémiai reakciókhoz.

Project Aquafluosense is designed to develop prototypes for a fluorescence-based instrumentation setup for in situ measurements of several characteristic parameters of water quality. In the scope of the project an enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the detection of several environmental xenobiotics, including mycotoxin zearalenone (ZON). ZON, produced by several plant pathogenic Fusarium species, has recently been identified as an emerging pollutant in surface water, presenting a hazard to aquatic ecosystems. Due to its physico-chemical properties, detection of ZON at low concentrations in surface water is a challenging task. The 96-well microplate-based fluorescence instrument is capable of detecting ZON in the concentration range of 0.09–400 ng/mL. The sensitivity and accuracy of the analytical method has been demonstrated by a comparative assessment with detection by high-performance liquid chromatography and by total internal reflection ellipsometry. The limit of detection of the method, 0.09 ng/mL, falls in the low range compared to the other reported immunoassays, but the main advantage of this ELFIA method is its efficacy in combined in situ applications for determination of various important water quality parameters detectable by induced fluorimerty—e.g., total organic carbon content, algal density or the level of other organic micropollutants detectable by immunofluorimetry. In addition, the immunofluorescence module can readily be expanded to other target analytes if proper antibodies are available for detection.

This work demonstrates the most widely used characterization methods and techniques of the supermolecular and lamellar structure of semicrystalline polymers. Polarized optical microscopy (POM) equipped with a hot-stage (thermo-optical microscopy, TOM), brightfield microscopy (BF), darkfield microscopy (DF), digital image processing techniques, optical profilometry (OP), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used as investigation techniques. The same iPP grade was used with different sample preparation techniques to compare these methods. The advantages and drawbacks of the sample preparation and investigation methods were discussed. The results show how the introduced techniques could reveal different kinds of information, and it is also shown how the experimental techniques should be matched to the goals of a structural study.

There is an urgent quest for room-temperature qubits in nanometer-sized, ultrasmall nanocrystals for quantum biosensing, hyperpolarization of biomolecules, and quantum information processing. Thus far, the preparation of such qubits at the nanoscale has remained futile. Here, we present a synthesis method that avoids any interaction of the solid with high-energy particles and uses self-propagated high-temperature synthesis with a subsequent electrochemical method, the no-photon exciton generation chemistry to produce room-temperature qubits in ultrasmall nanocrystals of sizes down to 3 nm with high yield. We first create the host silicon carbide (SiC) crystallites by high-temperature synthesis and then apply wet chemical etching, which results in ultrasmall SiC nanocrystals and facilitates the creation of thermally stable defect qubits in the material. We demonstrate room-temperature optically detected magnetic resonance signal of divacancy qubits with 3.5% contrast from these nanoparticles with emission wavelengths falling in the second biological window (1000-1380 nm). These results constitute the formation of nonperturbative bioagents for quantum sensing and efficient hyperpolarization.