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1.
Ahmad Guji Yahaya Tomohiro Okuyama Jaroslav Kristof Marius Gabriel Blajan Kazuo Shimizu 《Molecules (Basel, Switzerland)》2021,26(9)
The direct and indirect bactericidal effects of dielectric barrier discharge (DBD) cold atmospheric-pressure microplasma in an air and plasma jet generated in an argon-oxygen gas mixture was investigated on Staphylococcus aureus and Cutibacterium acnes. An AC power supply was used to generate plasma at relatively low discharge voltages (0.9–2.4 kV) and frequency (27–30 kHz). Cultured bacteria were cultivated at a serial dilution of 10−5, then exposed to direct microplasma treatment and indirect treatment through plasma-activated water (PAW). The obtained results revealed that these methods of bacterial inactivation showed a 2 and 1 log reduction in the number of survived CFU/mL with direct treatment being the most effective means of treatment at just 3 min using air. UV–Vis spectroscopy confirmed that an increase in treatment time at 1.2% O2, 98.8% Ar caused a decrease in O2 concentration in the water as well as a decrease in absorbance of the peaks at 210 nm, which are attributed NO2− and NO3− concentration in the water, termed denitratification and denitritification in the treated water, respectively. 相似文献
2.
Andrea Macrelli Nicol Simone Villa Andrea Lucotti David Dellasega Paolo Maria Ossi Matteo Tommasini 《Molecules (Basel, Switzerland)》2022,27(1)
The applications of SERS in therapeutic drug monitoring, or other fields of analytical chemistry, require the availability of sensitive sensors and experimental approaches that can be implemented in affordable ways. In this contribution, we show the production of cost-effective SERS sensors obtained by depositing Lee-Meisel Ag colloids on filter paper either by natural sedimentation or centrifugation. We have characterized the morphological and plasmonic features of the sensors by optical microscopy, SEM, and UV-Vis spectroscopy. Such sensors can be used to quantify by SERS the anti-epileptic drug Perampanel (in the concentration range 1 × 10−4–5 × 10−6 M) by spinning them during the micro-Raman measurements on the top of a custom device obtained from spare part hard disk drives. This approach minimizes laser-induced heating effects and allows averaging over the spatial non-uniformity of the sensor. 相似文献
3.
Modeling results are presented to compare the characteristics of laminar and turbulent argon thermal plasma jets issuing into ambient air. The combined-diffusion-coefficient method and the turbulence-enhanced combined-diffusion-coefficient method are employed to treat the diffusion of ambient air into the laminar and turbulent argon plasma jects, respectively. It is shown that since only the molecular diffusion mechanism is involved in the laminar plasma jet, the mass flow rate of ambient air entrained into the laminar plasma jet is comparatively small and less dependent on the jet inlet velocity. On the other hand, since turbulent transport mechanism is dominant in the turbulent plasma jet, the entrainment rate of ambient air into the turbulent plasma jet is about one order of magnitude larger and almost directly proportional to the jet inlet velocity. As a result, the characteristics of laminar plasma jets are quite different from those of turbulent plasma jets. The length of the high-temperature region of the laminar plasma jet is much longer and increases notably with increasing jet inlet velocity or inlet temperature, while the length of the high-temperature region of the turbulent plasma jet is short and less influenced by the jet inlet velocity or inlet temperature. The predicted results are reasonably consistent with available experimental observation by using a DC arc plasma torch at arc currents 80–250 A and argon flow rates (1.8–7.0)×10−4 kg/s. 相似文献
4.
Ewelina Skowron Kaja Spilarewicz-Stanek Dariusz Guziejewski Kamila Koszelska Radovan Metelka Sylwia Smarzewska 《Molecules (Basel, Switzerland)》2022,27(7)
The analytical performance of the clay paste electrode and graphene paste electrode was compared using square wave voltammetry (SWV) and cyclic voltammetry (CV). The comparison was made on the basis of a paracetamol (PA) determination on both working electrodes. The influence of pH and SWV parameters was investigated. The linear concentration ranges were found to be 6.0 × 10−7–3.0 × 10−5 and 2.0 × 10−6–8.0 × 10−5 mol L−1 for clay paste electrode (ClPE) and graphene paste electrode (GrPE), respectively. The detection and quantification limits were calculated as 1.4 × 10−7 and 4.7 ×10−7 mol L−1 for ClPE and 3.7 × 10−7 and 1.2 × 10−6 mol L−1 for GrPE, respectively. Developed methods were successfully applied to pharmaceutical formulations analyses. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize ClPE and GrPE surfaces. Clay composition was examined with wavelength dispersive X-ray (WDXRF). 相似文献
5.
Aleksandra Owczarzy Andrzej Ziba Jadwiga Poycka Karolina Kulig Wojciech Rog Agnieszka Szkudlarek Magorzata Maciek-Jurczyk 《Molecules (Basel, Switzerland)》2021,26(16)
Plasma proteins play a fundamental role in living organisms. They participate in the transport of endogenous and exogenous substances, especially drugs. 5-alkyl-12(H)-quino[3,4-b][1,4]benzothiazinium salts, have been synthesized as potential anticancer substances used for cancer treatment. Most anticancer substances generate a toxic effect on the human body. In order to check the toxicity and therapeutic dosage of these chemicals, the study of ligand binding to plasma proteins is very relevant. The present work presents the first comparative analysis of the binding of one of the 5-alkyl-12(H)-quino[3,4-b][1,4]benzothiazinium derivatives (Salt1) with human serum albumin (HSA), α-1-acid glycoprotein (AGP) and human gamma globulin (HGG), assessed using fluorescence, UV-Vis and CD spectroscopy. In order to mimic in vivo ligand–protein binding, control normal serum (CNS) was used. Based on the obtained data, the Salt1 binding sites in the tertiary structure of all plasma proteins and control normal serum were identified. Both the association constants (Ka) and the number of binding site classes (n) were calculated using the Klotz method. The strongest complex formed was Salt1–AGPcomplex (Ka = 7.35·104 and 7.86·104 mol·L−1 at excitation wavelengths λex of 275 and 295 nm, respectively). Lower values were obtained for Salt1–HSAcomplex (Ka = 2.45·104 and 2.71·104 mol·L−1) and Salt1–HGGcomplex (Ka = 1.41·104 and 1.33·104 mol·L−1) at excitation wavelengths λex of 275 and 295 nm, respectively, which is a positive phenomenon and contributes to the prolonged action of the drug. Salt1 probably binds to the HSA molecule in Sudlow sites I and II; for the remaining plasma proteins studied, only one binding site was observed. Moreover, using circular dichroism (CD), fluorescence and UV-Vis spectroscopy, no effect on the secondary and tertiary structures of proteins in the absence or presence of Salt1 has been demonstrated. Despite the fact that the conducted studies are basic, from the scientific point of view they are novel and encourage further in vitro and in vivo investigations. As a next part of the study (Part 2), the second new synthetized quinobenzothiazine derivative (Salt2) will be analyzed and published. 相似文献
6.
Abdul Ahad Faiyaz Shakeel Mohammad Raish Ajaz Ahmad Yousef A. Bin Jardan Fahad I. Al-Jenoobi Abdullah M. Al-Mohizea 《Molecules (Basel, Switzerland)》2022,27(4)
The solubility parameters, and solution thermodynamics of temozolomide (TMZ) in 10 frequently used solvents were examined at five different temperatures. The maximum mole fraction solubility of TMZ was ascertained in dimethyl sulfoxide (1.35 × 10−2), followed by that in polyethylene glycol-400 (3.32 × 10−3) > Transcutol® (2.89 × 10−3) > ethylene glycol (1.64 × 10−3) > propylene glycol (1.47 × 10−3) > H2O (7.70 × 10−4) > ethyl acetate (5.44 × 10−4) > ethanol (1.80 × 10−4) > isopropyl alcohol (1.32 × 10−4) > 1-butanol (1.07 × 10−4) at 323.2 K. An analogous pattern was also observed for the other investigated temperatures. The quantitated TMZ solubility values were regressed using Apelblat and Van’t Hoff models and showed overall deviances of 0.96% and 1.33%, respectively. Apparent thermodynamic analysis indicated endothermic, spontaneous, and entropy-driven dissolution of TMZ in all solvents. TMZ solubility data may help to formulate dosage forms, recrystallize, purify, and extract/separate TMZ. 相似文献
7.
Anna V. Nomin Cdric Noel Thomas Gries Alexandre Nomin Valentin A. Milichko Thierry Belmonte 《Molecules (Basel, Switzerland)》2021,26(23)
Time-resolved optical emission spectroscopy of nanosecond-pulsed discharges ignited in liquid nitrogen between two bismuth electrodes is used to determine the main discharge parameters (electron temperature, electron density and optical thickness). Nineteen lines belonging to the Bi I system and seven to the Bi II system could be recorded by directly plunging the optical fibre into the liquid in close vicinity to the discharge. The lack of data for the Stark parameters to evaluate the broadening of the Bi I lines was solved by taking advantage of the time-resolved information supported by each line to determine them. The electron density was found to decrease exponentially from 6.5 ± 1.5 × 1016 cm−3 200 ns after ignition to 1.0 ± 0.5 × 1016 cm−3 after 1050 ns. The electron temperature was found to be 0.35 eV, close to the value given by Saha’s equation. 相似文献
8.
Nazrul Haq Adel F. Alghaith Sultan Alshehri Faiyaz Shakeel 《Molecules (Basel, Switzerland)》2022,27(13)
This study examines the solubility and thermodynamics of febuxostat (FBX) in a variety of mono solvents, including “water, methanol (MeOH), ethanol (EtOH), isopropanol (IPA), 1-butanol (1-BuOH), 2-butanol (2-BuOH), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), Transcutol-HP (THP), and dimethyl sulfoxide (DMSO)” at 298.2–318.2 K and 101.1 kPa. The solubility of FBX was determined using a shake flask method and correlated with “van’t Hoff, Buchowski-Ksiazczak λh, and Apelblat models”. The overall error values for van’t Hoff, Buchowski-Ksiazczak λh, and Apelblat models was recorded to be 1.60, 2.86, and 1.14%, respectively. The maximum mole fraction solubility of FBX was 3.06 × 10−2 in PEG-400 at 318.2 K, however the least one was 1.97 × 10−7 in water at 298.2 K. The FBX solubility increased with temperature and the order followed in different mono solvents was PEG-400 (3.06 × 10−2) > THP (1.70 × 10−2) > 2-BuOH (1.38 × 10−2) > 1-BuOH (1.37 × 10−2) > IPA (1.10 × 10−2) > EtOH (8.37 × 10−3) > EA (8.31 × 10−3) > DMSO (7.35 × 10−3) > MeOH (3.26 × 10−3) > PG (1.88 × 10−3) > EG (1.31 × 10−3) > water (1.14 × 10−6) at 318.2 K. Compared to the other combinations of FBX and mono solvents, FBX-PEG-400 had the strongest solute-solvent interactions. The apparent thermodynamic analysis revealed that FBX dissolution was “endothermic and entropy-driven” in all mono solvents investigated. Based on these findings, PEG-400 appears to be the optimal co-solvent for FBX solubility. 相似文献
9.
Xiaorui Zhang Chao Han Xinxing Zhou Frdric Otto Fan Zhang 《Molecules (Basel, Switzerland)》2021,26(23)
Soybean-derived bio-oil is one of the vegetable-based oils that is gaining the most interest for potential use in the rejuvenation of aged asphalt binders. This laboratory study was conducted to characterize and quantify the diffusion and rheological properties of bio-oil-rejuvenated aged asphalt binder (BRAA) using soybean oil. In the study, the chemical structure of the soybean oil was comparatively characterized using an element analyzer (EA), gel permeation chromatography (GPC), and a Fourier infrared (FTIR) spectrometer, respectively. Based on the chemical structure of the bio-oil, BRAA molecular models were built for computing the diffusion parameters using molecular dynamic simulations. Likewise, a dynamic shear rheometer (DSR) test device was used for measuring and quantifying the rheological properties of the aged asphalt binder rejuvenated with 0%, 1%, 2%, 3%, 4%, and 5% soybean oil, respectively. The laboratory test results indicate that bio-oil could potentially improve the diffusion coefficients and phase angle of the aged asphalt binder. Similarly, the corresponding decrease in the complex shear modulus has a positive effect on the low-temperature properties of BRAA. For a bio-oil dosage 4.0%, the diffusion coefficients of the BRAA components are 1.52 × 10−8, 1.33 × 10−8, 3.47 × 10−8, 4.82 × 10−8 and 3.92 × 10−8, respectively. Similarly, the corresponding reduction in the complex shear modulus from 1.27 × 107 Pa to 4.0 × 105 Pa suggests an improvement in the low-temperature properties of BRAA. Overall, the study contributes to the literature on the potential use of soybean-derived bio-oil as a rejuvenator of aged asphalt binders. 相似文献
10.
Maria A. Morosanova Tatyana V. Fedorova Alexandra S. Polyakova Elena I. Morosanova 《Molecules (Basel, Switzerland)》2020,25(24)
In the present work crude Agaricus bisporus extract (ABE) has been prepared and characterized by its tyrosinase activity, protein composition and substrate specificity. The presence of mushroom tyrosinase (PPO3) in ABE has been confirmed using two-dimensional electrophoresis, followed by MALDI TOF/TOF MS-based analysis. GH27 alpha-glucosidases, GH47 alpha-mannosidases, GH20 hexosaminidases, and alkaline phosphatases have been also detected in ABE. ABE substrate specificity has been studied using 19 phenolic compounds: polyphenols (catechol, gallic, caffeic, chlorogenic, and ferulic acids, quercetin, rutin, dihydroquercetin, l-dihydroxyphenylalanine, resorcinol, propyl gallate) and monophenols (l-tyrosine, phenol, p-nitrophenol, o-nitrophenol, guaiacol, o-cresol, m-cresol, p-cresol). The comparison of ABE substrate specificity and affinity to the corresponding parameters of purified A. bisporus tyrosinase has revealed no major differences. The conditions for spectrophotometric determination have been chosen and the analytical procedures for determination of 1.4 × 10−4–1.0 × 10−3 M l-tyrosine, 3.1 × 10−6–1.0 × 10−4 M phenol, 5.4 × 10−5–1.0 × 10−3 M catechol, 8.5 × 10−5–1.0 × 10−3 M caffeic acid, 1.5 × 10−4–7.5 × 10−4 M chlorogenic acid, 6.8 × 10−5–1.0 × 10−3 M l-DOPA have been proposed. The procedures have been applied for the determination of l-tyrosine in food supplements, l-DOPA in synthetic serum, and phenol in waste water from the food manufacturing plant. Thus, we have demonstrated the possibility of using ABE as a substitute for tyrosinase in such analytical applications, as food supplements, medical and environmental analysis. 相似文献
11.
Kazuaki Wagatsuma 《Analytical and bioanalytical chemistry》2009,393(8):2067-2074
The emission characteristics of ionic lines of nickel, cobalt, and vanadium were investigated when argon or krypton was employed
as the plasma gas in glow discharge optical emission spectrometry. A dc Grimm-style lamp was employed as the excitation source.
Detection limits of the ionic lines in each iron-matrix alloy sample were compared between the krypton and the argon plasmas.
Particular intense ionic lines were observed in the emission spectra as a function of the discharge gas (krypton or argon),
such as the Co II 258.033 nm for krypton and the Co II 231.707 nm for argon. The explanation for this is that collisions with
the plasma gases dominantly populate particular excited levels of cobalt ion, which can receive the internal energy from each
gas ion selectively, for example, the 3d74p 3G5 (6.0201 eV) for krypton and the 3d74p 3G4 (8.0779 eV) for argon. In the determination of nickel as well as cobalt in iron-matrix samples, more sensitive ionic lines
could be found in the krypton plasma rather than the argon plasma. Detection limits in the krypton plasma were 0.0039 mass%
Ni for the Ni II 230.299-nm line and 0.002 mass% Co for the Co II 258.033-nm line. However, in the determination of vanadium,
the argon plasma had better analytical performance, giving a detection limit of 0.0023 mass% V for the V II 309.310-nm line. 相似文献
12.
Masakazu Kobayashi Takuya Honda Atsushi Kanzawa 《Plasma Chemistry and Plasma Processing》1984,4(1):43-57
The momentum and energy transfer phenomena with large temperature difference were investigated experimentally and theoretically, using an argon atmospheric thermal plasma. The plasma was generated by an arc discharge, 4–6 kW, and flowed into a water-cooled copper tube for static pressure measurements and into a copper block with the same size hole (8 mm i.d.) for measuring heat fluxes using a transient method. The argon flow rate was 2.77–8.31×10–4 kg/s. The static pressure of the plasma flow shows a different variation from that of an ordinary flow and does not decrease monotonically. The axial distributions of the numerical calculations are in fair agreement with those of the experiments, and it is concluded that the contributions of recombination and of physical properties play important roles in the behavior of the confined thermal plasma flow. 相似文献
13.
Luis D. Gmez-Mndez Luis C. Jimnez-Borrego Alejandro Prez-Flrez Raúl A. Poutou-Piales Aura M. Pedroza-Rodríguez Juan C. Salcedo-Reyes Andrs Vargas Johan M. Bogoya 《Molecules (Basel, Switzerland)》2021,26(9)
Low-density polyethylene (LDPE) sheets (3.0 ± 0.1 cm) received sequential treatment, first by the action of direct-current low-pressure plasma (DC-LPP) with a 100% oxygen partial pressure, 3.0 × 10−2 mbar pressure, 600 V DC tension, 5.6 cm distance, 6-min treatment. Then, sheets were submitted to TiO2 photocatalysis at UV radiation at 254 nm (TiO2/UV) with a pH value of 4.5 ± 0.2 and a TiO2 concentration of 1 gL−1. We achieved a complementary effect on the transformation of LDPE films. With the first treatment, ablation was generated, which increased hydrophilicity. With the second treatment, the cavities appeared. The changes in the LDPE sheets’ hydrophobicity were measured using the static contact angle (SCA) technique. The photocatalytic degradation curve at 400 h revealed that the DC-LPP photocatalysis sequential process decreased SCA by 82°. This was achieved by the incorporation of polar groups, which increased hydrophilicity, roughness, and rigidity by 12 and 38%, respectively. These sequential processes could be employed for LDPE and other material biodegradation pretreatment. 相似文献
14.
Lea Kukoc-Modun Tomislav Kraljevi Dimitrios Tsikas Njegomir Radi Darko Modun 《Molecules (Basel, Switzerland)》2021,26(22)
A new flow injection spectrophotometric method for the determination of N-acetyl-l-cysteine ethyl ester (NACET) was developed and validated. The method is based on the reduction of Cu(II)-ligand complexes to chromophoric Cu(I)-ligand complexes with the analyte. The studied ligands were neocuproine (NCN), bicinchoninic acid (BCA) and bathocuproine disulfonic acid (BCS). The absorbance of the Cu(I)-ligand complex was measured at 458, 562 and 483 nm for the reactions of NACET with NCN, BCA and BCS, respectively. The method was validated in terms of linear dynamic range, limit of detection and quantitation, accuracy, selectivity, and precision. Experimental conditions were optimized by a univariate method, yielding linear calibration curves in a concentration range from 2.0 × 10−6 mol L−1 to 2.0 × 10−4 mol L−1 using NCN; 2.0 × 10−6 mol L−1 to 1.0 × 10−4 mol L−1 using BCA and 6.0 × 10−7 mol L−1 to 1.2 × 10−4 mol L−1 using BCS. The achieved analytical frequency was 90 h−1 for all three ligands. The method was successfully employed for NACET determination in pharmaceutical preparations, indicating that this FIA method fulfilled all the essential demands for the determination of NACET in quality control laboratories, as it combined low instrument and reagent costs with a high sampling rate. 相似文献
15.
Willian Robert Caliman Franciani Cassia Sentanin Rodrigo Cesar Sabadini Jose Pedro Donoso Claudio Jose Magon Agnieszka Pawlicka 《Molecules (Basel, Switzerland)》2022,27(24)
Nanocomposite polymer electrolytes (NPEs) were obtained using gellan gum (GG) and 1 to 40 wt.% of montmorillonite (Na+SYN-1) clay. The NPEs were crosslinked with formaldehyde, plasticized with glycerol, and contained LiClO4. The samples were characterized by impedance spectroscopy, thermal analyses (TGA and DSC), UV-vis transmittance and reflectance, X-ray diffraction (XRD), and continuous-wave electron paramagnetic resonance (CW-EPR). The NPEs of GG and 40 wt.% LiClO4 showed the highest conductivity of 2.14 × 10−6 and 3.10 × 10−4 S/cm at 30 and 80 °C, respectively. The samples with 10 wt.% Na+SYN-1 had a conductivity of 1.86 × 10−5 and 3.74 × 10−4 S/cm at 30 and 80 °C, respectively. TGA analyses revealed that the samples are thermally stable up to 190 °C and this did not change with clay addition. The transparency of the samples decreased with the increase in the clay content and at the same time their reflectance increased. Finally, CW-EPR was performed to identify the coordination environment of Cu2+ ions in the GG NPEs. The samples doped with the lowest copper concentration exhibit the typical EPR spectra due to isolated Cu2+ ions in axially distorted sites. At high concentrations, the spectra become isotropic because of dipolar and exchange magnetic effects. In summary, GG/clay NPEs presented good ionic conductivity results, which qualifies them for electrochemical device applications. 相似文献
16.
An analytical procedure regarding the determination of selenium(IV) by anodic stripping voltammetry exploiting the in situ plated bismuth film electrode is described. Since organics are commonly present in untreated natural water samples, the use of Amberlite XAD-7 resin turns out to be quite important to avoid problems such as the adsorption of these compounds on the working electrode. The optimum circumstances for the detection of selenium in water using differential pulse voltammetry techniques were found to be as follows: 0.1 mol L−1 acetic acid, 1.9 × 10−5 mol L−1 Bi(III), 0.1 g Amberlite XAD-7 resin, and successive potentials of −1.6 V for 5 s and −0.4 V for 60 s, during which the in situ formation of the bismuth film on glassy carbon and the accumulation of selenium took place. The current of the anodic peak varies linearly with the selenium concentration ranging from 3 × 10−9 mol L−1 to 3 × 10−6 mol L−1 (r = 0.9995), with a detection limit of 8 × 10−10 mol L−1. The proposed procedure was used for Se(IV) determination in certified reference materials and natural water samples, and acceptable results and recoveries were obtained. 相似文献
17.
Xiaokai Zhang Daria A. Barkova Pavel V. Koshlyakov Ilya E. Gerasimov Evgeni N. Chesnokov Lev N. Krasnoperov 《Molecules (Basel, Switzerland)》2022,27(7)
The kinetics of the reaction of hydroxyl radical (OH) with dimethyl methylphosphonate (DMMP, (CH3O)2CH3PO) (reaction 1) OH + DMMP → products (1) was studied at the bath gas (He) pressure of 1 bar over the 295–837 K temperature range. Hydroxyl radicals were produced in the fast reaction of electronically excited oxygen atoms O(1D) with H2O. The time-resolved kinetic profiles of hydroxyl radicals were recorded via UV absorption at around 308 nm using a DC discharge H2O/Ar lamp. The reaction rate constant exhibits a pronounced V-shaped temperature dependence, negative in the low temperature range, 295–530 K (the rate constant decreases with temperature), and positive in the elevated temperature range, 530–837 K (the rate constant increases with temperature), with a turning point at 530 ± 10 K. The rate constant could not be adequately fitted with a standard 3-parameter modified Arrhenius expression. The data were fitted with a 5-parameter expression as: k1 = 2.19 × 10−14(T/298)2.43exp(15.02 kJ mol−1/RT) + 1.71 × 10−10exp(−26.51 kJ mol−1/RT) cm3molecule−1s−1 (295–837 K). In addition, a theoretically predicted pressure dependence for such reactions was experimentally observed for the first time. 相似文献
18.
Optical and Photoacoustic Properties of Laser-Ablated Silver Nanoparticles in a Carbon Dots Solution
Amir Reza Sadrolhosseini Ganesan Krishnan Suhaidi Shafie Suraya Abdul Rashid Sulaiman Wadi Harun 《Molecules (Basel, Switzerland)》2020,25(24)
This study used the carbon dots solution for the laser ablation technique to fabricate silver nanoparticles. The ablation time range was from 5 min to 20 min. Analytical methods, including Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, transmission electron microscopy, and Raman spectroscopy were used to categorize the prepared samples. The UV-visible and z-scan techniques provided optical parameters such as linear and nonlinear refractive indices in the range of 1.56759 to 1.81288 and 7.3769 × 10−10 cm2 W−1 to 9.5269 × 10−10 cm2 W−1 and the nonlinear susceptibility was measured in the range of 5.46 × 10−8 to 6.97 × 10−8 esu. The thermal effusivity of prepared samples, which were measured using the photoacoustic technique, were in the range of 0.0941 W s1/2 cm−2 K−1 to 0.8491 W s1/2 cm−2 K−1. The interaction of the prepared sample with fluoride was investigated using a Raman spectrometer. Consequently, the intensity of the Raman signal decreased with the increasing concentration of fluoride, and the detection limit is about 0.1 ppm. 相似文献
19.
In the present study, the seasonal variability of the in vitro ferric reducing ability of plasma (FRAP), total phenols, and terpene hydrocarbon content in 70% ethanol extracts were evaluated. The samples of crushed (CBs) and non-crushed ripe juniper berries (NCBs) collected at five localities in North-East Slovakia during the years 2012–2014 were compared. The method of preparation of the extract influenced the amount of dry matter (DM) in the extracts. In the CB extracts were statistically higher contents of DM (from 13.91 ± 0.11 g·L−1 to 23.84 ± 0.14 g·L−1) compared to NCB extracts (from 1.39 ± 0.01 g·L−1 to 16.55 ± 0.09 g·L−1). The differences in antioxidant activity between the investigated localities were statistically significant for both types of extract. For example, in 2013 in the locality of Zbojné, the FRAP in NCBs was 76.62 µmol·L−1·g−1 DM and in CBs was 138.27 µmol·L−1·g−1 DM, while in the Miľpoš locality, in NCBs there was 232.66 µmol·L−1·g−1 DM and in CBs there was 1178.98 µmol·L−1·g−1 DM. The differences in the antioxidant activity between the studied years in the case of NCB extracts were not statistically significant. In the case of CB extracts, significant differences between the evaluated years were found. Statistics by ANOVA confirmed that CB extracts prepared from berries in the year 2013 showed significantly higher activity compared to CB extracts from berries from the years 2012 and 2014. Based on the Pearson we found a negative correlation coefficient between the FRAP assay and the content of total polyphenols in NCB extracts (−0.531 in 2012; −0.349 in 2013; and −0.224 in 2014). In contrast, CB extracts showed a positive correlation coefficient (0.843 in 2012; 0.742 in 2013; 0.617 in 2014). 相似文献
20.
Simion Bogdan Angyus Erika Levei Dorin Petreus Radu Etz Eniko Covaci Oana Teodora Moldovan Michaela Ponta Eugen Darvasi Tiberiu Frentiu 《Molecules (Basel, Switzerland)》2021,26(9)
The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min−1) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180–210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02–0.75 mg kg−1) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86–116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation. 相似文献