Glass Test Tubes Research Articles

Thermal Response to High-Power Holmium Laser Lithotripsy.

The aim of this study was to investigate "caliceal" fluid temperature changes during holmium laser activation/lithotripsy using settings up to 40 W power output with different irrigation flow rates. The experimental system consisted of a glass test tube (diameter 10 mm/length 75 mm) filled with deionized water, to mimic a calix. Real-time temperature was recorded using a thermocouple (Physitemp, NJ) positioned 5 mm from the bottom of the tube. A 200 μm laser fiber (Flexiva; Boston Scientific, MA) was introduced through the working channel of a disposable ureteroscope (LithoVue; Boston Scientific) and the laser fiber tip was positioned 15 mm above the bottom of the test tube. Deionized water irrigation (room temperature) through the working channel of the ureteroscope was delivered at flow rates of 0, 7-8, 14-15, and 38-40 mL/minute. A 120-W holmium laser (pulse 120; Lumenis, CA) was used. The following settings were explored: 0.5 J × 10 Hz, 1.0 J × 10 Hz, 0.5 J × 20 Hz, 1.0 J × 20 Hz, 0.5 J × 40 Hz, 1.0 J × 40 Hz, and 0.5 J × 80 Hz. During each experiment, the laser was activated continuously for 60 seconds. Temperature increased with increasing laser power output and decreasing irrigation flow rate. The highest temperature, 70.3°C (standard deviation 2.7), occurred with laser setting of 1.0 J × 40 Hz and no irrigation after 60 seconds of continuous laser firing. None of the tested laser settings and irrigation parameters produced temperature exceeding 51°C when activated for only 10 seconds of continuous laser firing. High-power holmium settings fired in long bursts with low irrigation flow rates can generate high fluid temperatures in a laboratory "caliceal" model. Awareness of this risk allows urologist to implement a variety of techniques (higher irrigation flow rates, intermittent laser activation, and potentially cooled irrigation fluid) to control and mitigate thermal effects during holmium laser lithotripsy.

In situ-produced CO2-assisted dispersive liquid–liquid microextraction for extraction and preconcentration of cobalt, nickel, and copper ions from aqueous samples followed by graphite furnace atomic absorption spectrometry determination

In the present work, a new microextraction technique, namely in situ-produced CO2-assisted dispersive liquid–liquid microextraction was introduced for the extraction and preconcentration of cobalt, nickel, and copper from aqueous samples followed by graphite furnace atomic absorption spectrometry detection. The proposed method relies on the CO2 gas produced due to a chemical reaction as the disperser agent instead of the disperser solvent used in the conventional dispersive liquid–liquid microextraction. Initially, a solid mixture of tartaric acid and sodium bicarbonate was placed in the bottom of a dry conical glass test tube. Then µL level of 1,1,2,2-tetrachloroethane as the extraction solvent was added into the tube. An aqueous solution of the analytes containing sodium diethyldithiocarbamate (as chelating agent) was transferred into the tube. The reaction between tartaric acid and sodium bicarbonate was immediately occurred, and the produced CO2 led to dispersion of the extraction solvent as tiny droplets into the sample which resulted in extraction of the analytes into the organic solvent. The cloudy solution was centrifuged, and the sedimented phase was analyzed by the instrumental analytical method. Under the optimum conditions, the calibration curves were linear in the ranges of 20–300, 20–200, and 15–250 ng L−1 for Co2+, Ni2+, and Cu2+, respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.3 to 4.6 and 4.5–5.6% for intra- and inter-day (n = 6, C = 50 ng L−1) precisions, respectively. Moreover, the detection limits and enrichment factors of the selected analytes were obtained in the ranges of 6.2–12 and 139–150 ng L−1, respectively. The accuracy of the developed procedure was checked by analyzing NRCC-SLRS4 Riverine water as a certified reference material. Finally, the proposed method was successfully applied for the simultaneous analysis of the selected analytes in environmental water and fruit juice samples. The relative recoveries obtained for the analytes in the spiked samples were within in the range of 84–107%.

High-throughput analysis of softwood lignin using tetra-n-butylphosphonium hydroxide (TBPH)

The authors developed a high-throughput method for analyzing softwood lignin using tetra-n-butylphosphonium hydroxide (TBPH). Wood meal, TBPH, and hydrogen peroxide (H2O2) were introduced into a screw-capped glass test tube and allowed to react in a pressure cooker at 121 °C for 3 h to solubilize the wood meal. The solubilized polysaccharide was precipitated by the addition of a poor solvent such as methanol. After removal of the polysaccharide, the lignin concentration was measured via ultra-violet (UV) absorption spectroscopy. The series of operations performed was summarized as the TBPH method. The TBPH method was characterized as a simple and rapid procedure that used common equipment and was suitable for multiple-sample analysis. Softwood sample groups were prepared, and the lignin contents of these samples were measured by the TBPH method, the Klason method, and the acetyl bromide method to determine the accuracy of the proposed method. The TBPH method showed a high coefficient of determination (R2 = 0.94) when compared to the Klason method. By contrast, the acetyl bromide method showed a comparatively low correlation (R2 = 0.71) with the Klason method. This study revealed that the TBPH method presented high-throughput rapid analysis and good accuracy for soft wood lignin analysis.

Active control of supercooling degree using two surfactants of different molecular sizes

The authors have achieved active control of the supercooling degree by varying surfactant concentrations. To improve controllability of supercooling dissolution, the following experiments were carried out by different mixing methods using two kinds of surfactant of different molecular sizes. First, supercooling degrees were measured after dropping a “different” surfactant–pure water mixture with a fixed concentration onto a “base” surfactant–pure water mixture with a critical micelle concentration (CMC) in a glass test tube varying concentrations of the different surfactant-mixture. Second, supercooling degrees were measured after simultaneously mixing the mixture of a base surfactant at its CMC and a different surfactant of fixed concentration in a glass test tube varying the different surfactant-mixture concentrations. In both cases, adsorbed amounts of two surfactants to SiO2 surfaces were measured by a quartz crystal microbalance. Correlations among the mixing method, surfactant concentration of the total mixture, the supercooling degree and the adsorbed amount were clarified.

Model-based precision position and force control of SMA actuators with a clamping application

This paper presents a novel control strategy for precision control of Shape Memory Alloy (SMA) actuators by using a combination of large and small-signal controllers. The large-signal controller, responsible for coarse positioning, is a nonlinear PID (NPID) temperature controller that gets its desired temperature value online from a computationally efficient stress-strain and phase kinetics SMA model. The small-signal controller, responsible for fine positioning, is variable structure controller that uses an asymmetrical boundary layer to prevent over-heating of the wire. Further, the control signals adapt to the dynamic load on the wire to prevent overshoots. The control results show precise tracking control with exceptional disturbance rejection for various loads. The control strategy is then used for force control in an SMA-based clamping vice to clamp a thin-walled glass test tube. While the large-signal controller remains unchanged, the small-signal controller is used as a force controller rather than a position controller. The control unit of the vice is an embedded processor, on which the control algorithms run with a sample time of 3 ms. The vice is used to clamp the test tube at various desired step and sinusoidal forces and shows accurate force tracking and good disturbance rejection.

Dissolution Test of Tacrolimus Capsule: Effects of Filtration and Glass Adsorption.

Tacrolimus is a potent, narrow therapeutic index, immunosuppressive drug used to avoid organ rejection in patients that have undergone organ transplantation. Dissolution tests are widely used to evaluate drug product quality and performance. Analysis of tacrolimus during dissolution testing is sensitive to several factors, such as sample solution storage time and container material. The filtration process, tacrolimus glass adsorption, and sample solution storage time are found to impact the tacrolimus dissolution results. Based on observations in this work, the use of G4or equivalent filter flush before collection and polypropylene test tubes or vials instead of glass test tubes or vials are recommended for tacrolimus drug product dissolution test.

Demonstration of acoustic resonances in a cylindrical cavity applying the photoacoustic technique

In this work we present some experiments which can be performed in college or on the first courses of university to acquire knowledge about resonant acoustical phenomena in closed cavities in a tangible way, through experiments based on the photoacoustic effect in gases. This phenomenon consists in the generation of acoustic waves after optical excitation of an absorbing gas and further local heating of the non-absorbing surrounding gas by energy exchange through collisions between molecules of both species. Simple experiments, performed with daily live elements, can be very useful for teachers and students to get in touch with the phenomenon of acoustic resonances with the addition of concepts about light–matter interaction. The setups consist of the resonant cavity, the illumination source and the signal detection-acquisition scheme. In this paper a closed glass test tube is used as the resonant cavity and is filled with a mixture of nitrogen dioxide and air. The illumination is performed by a pulsed power LED modulated at different resonant frequencies of the cavity. A microphone inside the tube is connected to an oscilloscope which displays the photoacoustic signal. The LED is moved along the tube showing how different resonant modes can be excited.

Inhibition of Tetrahydrofuran Hydrate Formation in the Presence of Polyol-Modified Glass Surfaces.

Glycerol was conjugated to glass test tube surfaces in four configurations by employing two different silane spacers, covalent attachment to glycerol at either the 1- or the 2-position, and with a succinic acid spacer. The resulting surfaces were tested for their ability to inhibit the nucleation of tetrahydrofuran hydrate (THF hydrate) in comparison with polyvinylpyrrolidone (PVP), a known polymeric inhibitor of THF hydrate formation. Contact angle measurements were used as an indication of surface modification throughout the glass derivatization steps. Of the four final surfaces modified with glycerol, only the coating with (3-aminopropyl)triethoxysilane (APTES) and glycerol coupled at the 1-position (leaving a free 1,2-diol) showed significant inhibition of the formation of THF hydrate. The corresponding N-[3-(trimethoxysilyl)propyl]-ethylenediamine (AEAPTMS) coating with glycerol coupled at the 1-position did not show a significant difference over the untreated test tubes. Attachment of glycerol at the 2-position yielded a coating with no benefit over the untreated test tubes regardless of the silane used, and a surface modified with APTES and succinic acid alone enhanced the formation of THF hydrate. The ability to inhibit THF hydrate formation using a polyol-modified surface is a first step in the development of a coating that, alone or in combination with known gas hydrate inhibitors, could be used to prevent gas hydrates from plugging pipelines in field applications.

Cyclohexylamine as extraction solvent and chelating agent in extraction and preconcentration of some heavy metals in aqueous samples based on heat-induced homogeneous liquid-liquid extraction

A new sample preparation method has been developed for extraction and preconcentration of some heavy metal cations in aqueous samples using cyclohexylamine-based homogeneous liquid-liquid microextraction. In the proposed method, cyclohexylamine was used as both the complexing agent and the extraction solvent. For this purpose, cyclohexylamine at µL level was initially added into an aqueous solution containing Co(II), Ni(II), and Cu(II) ions which was placed in a glass test tube. The mixture was shaken for forming a homogeneous solution. Then sodium chloride was added to the solution. After shaking manually again, the test tube was placed in a water bath thermostated at 70°C. Due to lower solubility of cyclohexylamine at the elevated temperature, a cloudy solution was formed. The fine droplets of cyclohexylamine containing cation-cyclohexylamine complexes were collected on the top of the aqueous phase by centrifuging. The enriched analytes in the upper phase were determined by graphite furnace atomic absorption spectrometry. Several variables possibly affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curves were linear in the ranges of 80–1000, 40–700, and 80–800ngL−1 for Co2+, Ni2+, and Cu2+, respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 3.3% to 5.2% (n = 6, C = 200ngL−1). Moreover, the obtained detection limits of the selected analytes were in the range of 15.3–37.7ngL−1. The accuracy of the developed procedure was verified by analyzing a certified reference material, namely NRCC-SLRS4 Riverine water. Finally, the proposed method was successfully applied for the simultaneous analysis of the selected analytes in environmental water samples.

Stability of some clinical biochemistry parameters in equine serum/plasma stored at refrigerator and room temperatures: a preliminary study

Accurate measurement of clinical biochemistry parameters is an essential tool for the correct interpretation of clinical biochemistry abnormalities. A general problem faced by most clinical laboratories is inability to process blood samples received late or submitted in large numbers. This delay in sample processing is usually unavoidable. This present study evaluated the stability of some biochemistry parameters in equine blood before and after storage at room (25 °C) and refrigerator (4 °C) temperatures. Five milliliters of blood were collected from external jugular veins of 17 apparently healthy adult horses kept at Obollo Afor horse lairage, Enugu State. The blood samples were collected into anti-coagulant glass test tubes and in non-anticoagulant glass test tubes to harvest plasma and serum respectively. Serum and plasma were analyzed shortly (0 h), and then after storage at refrigerator and room temperatures, at 24, 48, 72 h. Standard procedures were followed in the determination of plasma Malondialdehyde (MDA), plasma glucose, serum calcium, sodium, potassium, and uric acid concentrations. Comparisons to the fresh samples (hour 0) (P < 0.05) revealed that plasma MDA was stable for 48 h at both 4 and 25 °C; serum uric acid, potassium, and calcium were stable, less than 24 h post sample collection, at both 4 and 25 °C. Serum sodium and plasma glucose were stable at 4 °C for up to 72 h. The results of this study suggest that the ideal temperature for storage of equine serum/plasma for serum sodium and plasma glucose determinations is 4 °C. Plasma stored for 48 h at either 4 or 25 °C is suitable for malondialdehyde determination. Also, serum uric acid, potassium, and calcium determinations should be carried out immediately upon separation of clotted blood from serum so as to avoid obtaining erroneous result.

Experimental study on freezing of liquids under static magnetic field

Abstract Freezing processes of several liquids under static magnetic field (SMF) less than 50 mT were investigated. Central temperature of liquid samples held in glass test tubes immersed in a liquid bath was measured and collected. Nucleation temperature and phase transition time were obtained from freezing curves. Normality tests were performed for nucleation temperature of these liquids with/without magnetic field and normality distributions were justified. Analysis of variances was carried out for nucleation temperature of these liquids with magnetic field flux density as the influencing factor. Results showed that no significant difference was found for deionized water with or without SMF. However, differences exist in 0.9% NaCl solution and 5% ethylene glycol solution with and without SMF. Nucleation temperature of 0.9% NaCl with SMF is lower than that without SMF, while its phase transition time is shorter than that without SMF. Nucleation temperature of 5% ethylene glycol with SMF is higher than that without SMF, while its phase transition time is not modified with SMF.

FUNGICIDAL POTENTIAL OF ALLELOPATHIC WEED Cenchrus pennisetiformis ON GROWTH OF Fusarium oxysporum f. sp. lycopersici UNDER CHROMIUM STRESS

ABSTRACT The present study was conducted to assess antifungal potential of the allelopathic grass Cenchrus pennisetiformis Hochst. &amp; Steud. against the fungal plant pathogen Fusarium oxysporum f. sp. lycopersici (cause of tomato wilt disease) under chromium stress. Laboratory experiments were performed in 10 mL volume glass test tubes each containing 1.0 mL of malt extract broth with seven concentrations (0, 50, 100, 150, 200, 250, 300 and 350 ppm) of each of Cr(III) and Cr(VI), and two concentrations (5% and 6%) of methanolic leaf, stem or root extract of C. pennisetiformis. A metal + weed extract amended medium was inoculated with the pathogen and incubated for 7 days at 25 C. Different concentrations of Cr(III) and Cr(VI) proved equally inhibitory resulting in 10-84% and 18-89% reduction in fungal biomass, respectively. Methanolic leaf, stem and root extracts of the weed reduced fungal biomass by 12-25%, 14-23% and 46-50%, respectively, over negative control. In combined application of methanolic extracts of different parts of C. pennisetiformis and metal solutions, root extract in combination with either Cr(III) or Cr(VI) showed the highest inhibitory potential against the fungus followed by leaf and stem extracts. In combination with methanolic root, leaf and stem extracts, different concentrations of Cr(III) and Cr(VI) significantly reduced fungal biomass by 54-99%, 14-99% and 9-95%, respectively, over negative control. Such studies have not been carried out previously. Results of the present investigation suggest that F. oxysporum oxysporum f. sp. lycopersici, the cause of Fusarium wilt disease in tomato, can be managed by application of extracts (or alternatively biomass) of C. pennisetiformis in chromium contaminated soils.

Gas chromatography for measurement of chlorpyrifos in serum

To investigate the method for the measurement of chlorpyrifos in serum by gas chromatography, and to provide a basis for emergency treatment of poisoning in clinical practice. Venous blood (3.0 ml) was collected from patients. After coagulation, the blood samples were centrifuged at 4 000 r/min for 5 minutes, and 0.5 ml of serum was placed in a glass test tube with a cork; 4.0 ml of ethyl acetate was then added and mixed rapidly, and this solution was subjected to extraction for 5 minutes and centrifuged at 4 000 r/min for 10 minutes. The ethyl acetate layer was placed in a conical tube and extracted twice with the same method. The extract was mixed and blow-dried with nitrogen, and the residue was dissolved with 50.0 μl ethanol. Gas chromatography was used for measurement, with a sample size of 1 μl and a retention time of 9.609 minutes. The linear range of this method was 0.2~20.0 μg/ml, and the regression equation was y=2 372.6x+357.2(r=0.999 6). The detection limit of chlorpyrifos in serum was 0.05 μg/ml, and the recovery rate was 84.6%~102.4%. The relative standard deviation was 3.6%~4.8%, and the intra-day and inter-day relative standard deviations were 3.62%~5.10% and 3.77%~4.98%, respectively. This detection method is accurate, simple, and convenient, and can be used for the clinical diagnosis of chlorpyrifos poisoning.

Axisymmetric diffraction of a cylindrical transverse wave by a viscoelastic spherical inclusion

In this paper, the scattering and diffraction of a cylindrical transverse shear wave in a viscoelastic isotropic medium by a spherical heterogeneity is analytically solved. The waves are generated by the harmonic longitudinal oscillations of the cylinder walls. The spherical inclusion is located at the radial center of the cylinder and differs from the cylindrical material only in its complex shear modulus. Small amplitude motion is assumed, such that linear system theory is valid. By employing multi-pole expansions, the incident and scattered wave fields are each defined in both cylindrical and spherical coordinates allowing for the satisfaction of the boundary conditions at the surfaces of these multiply connected bodies. The solution involves an infinite sum of improper integrals, which are evaluated numerically. The wave field is determined for a hydrogel (alginate) bead suspended in a different hydrogel (agarose) that fills a glass test tube. Numerical examples showing the effect on displacement fields of varying the stiffness of the inclusion are presented. This solution is further validated with a finite element simulation showing excellent agreement with the analytic results.

Determination of widely used non-steroidal anti-inflammatory drugs in biological fluids using simultaneous derivatization and air-assisted liquid–liquid microextraction followed by gas chromatography–flame ionization detection

A sensitive and reliable method for the extraction, preconcentration, and determination of non-steroidal acidic anti-inflammatory drugs (ibuprofen, naproxen, and diclofenac) from biological samples has been developed using simultaneous derivatization and air-assisted liquid–liquid microextraction followed by gas chromatography–flame ionization detection. In this method, a mixture of an extraction solvent (chloroform) and a derivatizing agent (butyl chloroformate) is added into a glass test tube containing an aqueous sample of the analytes and picoline (catalyst). The mixture is dispersed by repeatedly aspirating and dispensing via a syringe. By this action, derivatization and extraction of the selected analytes is performed simultaneously. Under the optimal conditions, enrichment factors and extraction recoveries were obtained in the ranges 364–412 and 72–82 %, respectively. The linear ranges were broad with correlation coefficients higher than 0.995. Limits of detection were obtained in the ranges 0.06–3.30 and 0.24–13 ng mL−1 in urine and plasma samples, respectively. Limits of quantification were 0.21–9.2 ng mL−1 in urine and 0.84–37 ng mL−1 for plasma sample. Relative standard deviations were lower than 5.2 % for six repeated determinations at a concentration of 25 ng mL−1 of each analyte. Finally, the developed method was successfully applied to determine the selected analytes in urine and plasma samples.

Gold Nanoparticles for In Vitro Diagnostics.

1.1. Significance of IVDs in the Clinic IVD test is a crucial component of clinical care that performs a diagnostic test on biological samples that have been taken from a living body, such as blood, urine, and tissue.1 Such tests are usually performed to determine or confirm the presence of disease in an individual. “In vitro” literally means “within the glass”, which indicates that the test was historically conducted in glass test tubes. In contrast, in vivo tests, literally “within the living”, are conducted within a whole, living organism including human body.2 IVD tests have received much public attention because of their distinct features in the medical profession. First, IVD tests do not interact with the human body directly, making such diagnosis accessible without invasive surgeries and thus saving a great deal of suffering. Second, the procedures of IVDs are performed on samples rather than human body, avoiding the possible biological safety problems on patients that often take place in the in vivo diagnostics. Third, an IVD test can quickly provide valuable information on a patient’s healthcare conditions. On the basis of the information, physicians or patients are able to make a timely decision for patient care or treatment. Fourth, the application of IVDs enables early diagnosis and makes treatment of serious diseases easier. Generally, the cost of early testing is much lower than that of the later on extensive treatment. Last, IVDs play a particularly vital role in remote settings for managing outbreaks of acute infectious diseases, where effective but simple diagnostic systems are highly desirable. These features make IVDs unique and of great importance among medical technologies.

Active control of supercooling degree using surfactant (In system with solid–liquid interface)

Supercooling reduces the COP of ice formation systems. So, control of supercooling dissolution is useful and would bring numerous benefits. In a previous report, the authors conducted an experiment to control supercooling dissolution in a mixture with a hydrophilic surfactant and water in a glass test tube which had the liquid–gas(air) interface, and it was possible to actively control average supercooling degree by varying the surfactant concentrations. The average supercooling degrees' tendencies below and over a critical micelle concentration, calculated based on the variation in surface tensions, were quite different. However, since the critical micelle concentration is a physical quantity concerned only with liquid–gas interface, it is essential to investigate phenomena in a system with a solid–liquid interface. So, in a syringe with a system having only a solid–liquid interface, possibility of active control of average supercooling degree by variation in surfactant concentrations is investigated.

The preparation of chicken tracheal organ cultures for virus isolation, propagation, and titration.

Chicken tracheal organ cultures (TOCs), comprising transverse sections of chick embryo trachea with beating cilia, have proved useful in the isolation of several respiratory viruses and as a viral assay system, using ciliostasis as the criterion for infection. A simple technique for the preparation of chicken tracheal organ cultures in glass test tubes, in which virus growth and ciliostasis can be readily observed, is described.

Instability of the hydrochloride salts of cathinone derivatives in air

We observed the decomposition of the hydrochloride salt of α-pyrrolidinoheptanophenone (α-PHPP-HCl), a newly distributed pyrrolidine-type cathinone derivative when 2.5ng of this substance was placed in glass test tubes and stored in a refrigerator for 3 days. To further investigate this phenomenon, we studied the (i) time course of the residual ratios of α-PHPP-HCl when a small amount (10μg) of α-PHPP-HCl was stored in glass vials in air at room temperature; (ii) identification of the decomposition products of α-PHPP-HCl; (iii) effect of air on the decomposition process; (iv) effect of the added amounts of α-PHPP-HCl on its decomposition; and (v) comparison of the stability between various cathinone derivatives and their decomposition products. The decomposition of α-PHPP-HCl occurred in air and increased with time. Two possible decomposition products, α-(2″-oxopyrrolidino)heptanophenone and α-PHPP-N-oxide, were identified. These products were formed by oxygen in air because the yield significantly decreased by storing them in a vacuum desiccator. With the decrease in the amount of α-PHPP-HCl, the residual ratios decreased and amount of the decomposition products increased. This indicates that the decomposition of α-PHPP-HCl occurred on the upper surface of the samples. The hydrochloride salts of other cathinone derivatives were also unstable in air, and the residual ratios observed were different depending on the compounds. The pyrrolidine-type cathinone derivatives afforded two types of decomposition products, which were presumed to be 2″-oxo and N-oxide derivatives, similar to α-PHPP-HCl. In contrast, secondary amine-type cathinone derivatives showed different decomposition patterns, possibly including the dealkylated derivative. These findings may be very useful for the future toxicological analysis of cathinone derivatives.

Labware Additives Identified to Be Selective Monoamine Oxidase-B Inhibitors

Plastic labware is used in all processes of modern pharmaceutical research, including compound storage and biological assays. The use of these plastics has created vast increases in productivity and cost savings as experiments moved from glass test tubes and capillary pipettes to plastic microplates and multichannel liquid handlers. One consequence of the use of plastic labware, however, is the potential release of contaminants and their resultant effects on biological assays. We report herein the identification of biologically active substances released from a commonly used plastic microplate. The active contaminants were identified by gas chromatography–mass spectroscopy as dodecan-1-ol, dodecyl 3-(3-dodecoxy-3-oxopropyl)sulfanylpropanoate, and dodecanoic acid, and they were found to be selective monoamine oxidase-B inhibitors.