Cold Fiber Research Articles

Application of poly 3,4-ethylenedioxythiophene and gold nanoparticles composite on a gold wire as a coating for determination of nitroaromatics in soil using cold fiber solid phase microextraction combined with gas chromatography

Although several sensing techniques have been employed for nitroaromatics, developing novel detection approaches for environment analysis is still necessary. In this study, for the first time, the cooling assisted solid phase microextraction (CA-SPME) method was performed using poly 3,4-ethylenedioxythiophene and gold nanoparticles composite coating on a gold wire to extract nitroaromatic compounds. The surface morphology of the homemade SPME fiber was investigated through a field emission scanning electron microscope. The fiber was used to extract 4-nitrotoluene (4-NT), 1,3-dinitrobenzene (1,3-DNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) from the soil. To increase extraction efficiency and reduce interferences, extraction was performed from the sample headspace, and the fiber was cooled by a cooling apparatus. Then, the extracts of nitroaromatics were injected into the gas chromatography- flame ionization detector instrument to identify and quantify the analytes. A set of effective experimental parameters in fiber coating characteristics and extraction and separation procedures, including extraction temperature, extraction time, vial volume, and separation conditions in gas chromatography, were optimized. Under optimal conditions, recoveries of nitroaromatics ranged from 96.80% to 102.10%, and the detection limit values were in the range of 0.15 to 0.30 ng.g−1. The linear ranges were obtained to be 0.5–250.0 ng.g−1 and 1.0–250.0 ng.g−1 for 4-NT, 2,4-DNT, 2,6-DNT, and 1,3-DNB, respectively. Finally, the proposed method was successfully tested on real soil samples.

Investigating cold Aδ fibers in the 0–40 °C temperature range: A quantitative sensory testing and evoked potentials study

ObjectiveTo evaluate the activity of cold Aδ-type fibers to thermal stimuli above human skin temperature (i.e., >32 °C). MethodsTwenty young adults aged 20–24 years participated in this study. The cold-detection threshold was measured from a basal temperature of 40 °C using an adaptive staircase method with high-speed cooling ramps (170 °C/s). A total of 150 stimulations at 36 °C, 32 °C, 28 °C, 24 °C, 20 °C, 16 °C, 12 °C, 8 °C, 4 °C and 0 °C (15 each) were performed. After each stimulation, subjects estimated the intensity of cold sensation using a visual analog scale, and evoked potentials were recorded. ResultsThe average cold-detection threshold was 35 °C (SD = 1.8). Regardless of the stimulation temperature, subjects reported a cooling sensation. Interestingly, reported increments in sensation were prominent for stimulation temperatures between 32 °C and 20 °C, but below this latter temperature sensations varied only very slightly. Evoked potential recordings revealed that decreasing temperature stimuli from a baseline of 40 °C induced a previously unreported N2P2 component with a mean N2 peak latency of 275 ms (SD = 13.1). The peak-to-peak amplitude of the N2P2 complex increased as the intensity of the cooling stimulation increased, exhibiting a profile comparable to subject-perceived intensity, namely, a major increase up to 20 °C, followed by a plateau to 0 °C. ConclusionsThe cool sensations reported by subjects were likely conveyed by Aδ fibers rather than by slow-conducting C fibers. Moreover, our rapid stimulation technique starting from a high temperature (40 °C) was capable of a) generating cold sensations at stimulation temperatures between 36 °C and 32 °C, and b) revealing the optimal activation range of Aδ fibers (20 °C–28 °C). Any decrease in temperature below this range did not result in a significant increase in sensation and thus probably did not evoke a significant increase in Aδ fiber activity. SignificanceThe regular assessment of cold sensation in peripheral neuropathies (i.e., with temperatures below 32 °C), could be completed by investigating cold-detection thresholds at temperatures ranging from 40 °C to 32 °C. Indeed, the absolute threshold of cold perception appears to start at 35 °C. Changes in the activation threshold of cold fibers were more easily detectable at this level.

Assessment of polycyclic aromatic hydrocarbons and derivatives in beer using a new cold fiber-solid phase microextraction system

Sample preparation assisted by a cooling system including solid phase microextraction (SPME) has received an increased interest in recent years. In this work, a new cold fiber (CF-SPME) system using thermoelectric cooling is proposed. The system consists of three thermoelectric coolers (Peltier), a heat sink, a recirculation module to dissipate the heat generated on the hot side, and an electric power source to generate the necessary voltage for the system. The Peltier keeps the SPME fiber cool during the extraction process.. This system was used to analyze polycyclic aromatic hydrocarbons (PAHs), and their nitrated (nitro-PAHs) and oxygenated (oxy-PAHs) derivatives, in commercial beers by gas chromatography coupled to mass spectrometry (GC/MS). The analyte's extraction was optimized through Doehlert design. Optimal extraction conditions were obtained with a salt content of 0.6% w/v and beer volume of 700.0 μL. The validated method showed limits of detection (LOD) in the range of 0.003–0.128 μg L−1 and limits of quantification (LOQ) from 0.011 to 0.427 μg L−1. Precision Coefficients of Variation values ranged from 3.0 to 18.7%, and recovery values of the analytes in beer varied between 80.1 and 100.3%. Among the PAHs derivatives evaluated in this study, only 9-fluorenone and 9-nitroanthracene were detected in some samples. Benzo[b]fluoranthene was the most detected analyte in the samples, and at least one PAH was detected in all samples. Principal component analysis (PCA) separated the samples into two groups, mainly due to the high relative concentrations of acenaphthene and chrysene. The cooling approach improved the extraction efficiency and the new system demonstrated high potential for portability and automation.

Application of Artificial Neural Network and Response Surface Methodology in Optimization of Cold Fiber Headspace Solid-Phase Microextraction (CF-HS-SPME) for Analysis of 2, 5-Hexandion in Urine Samples

Background: Cold-Fiber Solid-Phase Microextraction (CF-SPME) is often used for the extraction of volatile and semi-volatile compounds from complex matrices. Multivariate statistical optimization techniques can save time and chemicals and thus decrease the analytical cost in comparison with the Single Variable Approach (SVA). Over the past few decades, different beneficial mathematical tools have been developed for the optimization of separation processes. Objectives: In this study, the Artificial Neural Network (ANN) and Response Surface Methodology (RSM) applications were compared for CF-SPME optimization to determine 2, 5-hexandion in urine samples. 2, 5-Hexanedione is a colorless liquid and the main metabolite of n-hexane as a result of occupational exposure. Methods: N-hexane is widely used in the rubber industry, food processing, solvents, and medicinal drugs and has adverse effects such as neurotoxicity on humans. Thus, biological monitoring, analytic methods, and mathematical and statistical techniques concerning 2.5-HD are very important. The RSM and ANN are mathematical and statistical techniques applied for the optimization and process modeling. Designing an experiment based on the Historical Data Design (HDD) of RSM was adopted to evaluate the relationship between independent parameters such as extraction temperature, extraction time, sample volume, and extraction efficiency of 2, 5-hexandion. Results: The models were compared for their predictive ability by the coefficient of determination (R2) and Root Mean Square Error (RSME) based on the train and test dataset. Conclusions: The results were highly significant (P < 0.05) for the optimization of variables. The ANN model had more generalizability than the RSM model. Also, the ANN had higher predictive accuracy.

Repair of road surfaces using cold wet fiber containing asphalt concrete mixtures

During the construction of experimental sections of road surfaces in v. Ust-Kurdyum of the Saratov district of the Saratov region has been established the efficiency of production and application of cold fiber-containing dispersed-reinforced asphalt concrete mixtures with dispersed bitumen. A method for accelerating the formation of the structure of cold fiber-containing asphalt concrete by heat treatment of its surface is studied. Dispersed bitumen after drying the water film has good adhesion to concrete, asphalt concrete and other materials. The asphalt concrete formed as a result of curing on the basis of dispersed bitumen is high-strength, chemical-resistant, hydrophobic and environmentally friendly, corresponding to the existing regulatory requirements for asphalt concrete. For the production of asphalt mixtures, mass-produced equipment is suitable using materials commonly used in hot asphalt concrete: crushed stone, sand, mineral powder and bitumen. Operations on drying and heating of crushed stone and sand are excluded from the technological process. Asphalt concrete mix does not stick to the surface of rubberized rollers of vibratory rollers, which allows compacting mixtures with a high content of mineral powder at any time. There are fewer cracks on the surface of the compacted layer than when using a smooth-rolling roller. The technology is recommended for extended use on roads and streets of localities, and highways with low traffic intensity.

Phase distribution of polycyclic aromatic hydrocarbons and their oxygenated and nitrated derivatives in the ambient air of a Brazilian urban area☆

Air quality in large cities has worsened in recent years as a consequence people’s health is directly affected. Among the toxic compounds released to environmental air are polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (nitro-PAHs), and oxygenated PAHs (oxy-PAHs). Performant methods to analyze these compounds is necessary to enable adequate monitoring of air quality. Thus, this manuscript presents the development of a highly sensitive method to analyze PAHs, nitro-PAHs, and oxy-PAHs collected from ambient air (PM2.5) and the gas phase for a period of one year in the urban area of Belo Horizonte, Brazil. PAHs and their derivatives were extracted by cold fiber solid phase microextraction (CF-SPME) and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). The proposed method allows simultaneous analysis of 16 PAHs, nitro-PAHs and oxy-PAHs, presenting very good limits of detection and quantification, as well as appropriate precision and recovery. The results obtained for the period of one year allowed different studies. The compounds collected simultaneously from gas and particulate phase showed that total concentration of 16 PAHs were higher in the gas phase than in the particulate. On the other hand, nitro-PAHs and oxy-PAHs presented similar concentration in gas and particulate phases. The potential carcinogenicity of PAHs relative to benzo[a]pyrene showed benzo[a]pyrene equivalents of 0.49 ng m−3. The estimated risk of lifetime lung cancer was 5 × 10−5. Principal component analysis and diagnostic ratio was applied for source distribution indicating that burning of gasoline, diesel and biomass accounted for the PAHs profile in ambient air samples.

УСИЛЕНИЕ СТРОИТЕЛЬНЫХ КОНСТРУКЦИЙ ИЗ БЕТОНА СИСТЕМОЙ ВНЕШНЕГО АРМИРОВАНИЯ ИЗ УГЛЕПЛАСТИКА

The article describes the results of research work on the reinforcement of concrete structures via carbon reinforcing filler with a cold curing resin. As an object of research were selected: brand of concrete M-350 and experimental cold curing carbon fiber based on an epoxy matrix. The physico-mechanical characteristics of carbon fiber are investigated. The properties of concrete samples externally reinforced with carbon fiber after conducting full-scale exposure in various conditions and without it are investigated. It was established, that strength gain of reinforced samples compared to purely concrete samples is up to 550%.

Recent Applications and Newly Developed Strategies of Solid-Phase Microextraction in Contaminant Analysis: Through the Environment to Humans

The present review aims to describe the recent and most impactful applications in pollutant analysis using solid-phase microextraction (SPME) technology in environmental, food, and bio-clinical analysis. The covered papers were published in the last 5 years (2014–2019) thus providing the reader with information about the current state-of-the-art and the future potential directions of the research in pollutant monitoring using SPME. To this end, we revised the studies focused on the investigation of persistent organic pollutants (POPs), pesticides, and emerging pollutants (EPs) including personal care products (PPCPs), in different environmental, food, and bio-clinical matrices. We especially emphasized the role that SPME is having in contaminant surveys following the path that goes from the environment to humans passing through the food web. Besides, this review covers the last technological developments encompassing the use of novel extraction coatings (e.g., metal-organic frameworks, covalent organic frameworks, PDMS-overcoated fiber), geometries (e.g., Arrow-SPME, multiple monolithic fiber-SPME), approaches (e.g., vacuum and cold fiber SPME), and on-site devices. The applications of SPME hyphenated with ambient mass spectrometry have also been described.

P47-S Cold C-fibers sensitization to warm stimulation after ultraviolet B and heat-capsaicin exposure

Background Capsaicin, UV-B irradiation and electrical stimulation methods have been used to develop experimental hyperalgesia in Phase-I human studies. These sensitization models contribute to the study of the functional behavior of small fiber C-nociceptors. However, there is no published literature about functional changes of cold C-fibers using these models. Material and methods Skin sensitization was induced at the dorsum of the foot (superficial peroneal nerve) in two healthy volunteers using ultraviolet B radiation in one female and heat/capsaicin in one male. Microneurographic recordings were performed in the intermediate branch of the superficial peroneal nerve. Then trains of cold and warm stimuli, from 32 to 4 and 32 to 48-Celsius degrees respectively, were applied in the skin area of interest before and at least 45 min after induction of the skin sensitization models. Results Preliminary results showed a single cold C-fiber recorded in each subject. During cold stimulation, there were not functional variations in the cold receptors. Warm stimulation induced a reduction of the spontaneous firing rate of the cold fibers during the baseline recording in both models (room temperature at 25 °C). After the UVB and heat-capsaicin induction, the firing rate of the cold C-fibers in response to cold stimuli was increased. All cold C-fibers recorded became also sensitized to warm stimuli. Conclusions The ultraviolet B radiation and the heat-capsaicin sensitization models sensitize cutaneous cold C fibers to warmth. Some cases of warm allodynia in humans could partially be explained by skin sensitization after inflammatory processes (e.g., sunburn or thermal/chemical exposure).

Determination of polycyclic aromatic hydrocarbons and their nitrated and oxygenated derivatives in coffee brews using an efficient cold fiber-solid phase microextraction and gas chromatography mass spectrometry method

Polycyclic aromatic hydrocarbons (PAHs) are food contaminants; besides, their oxygenated (oxy-PAHs) and nitrated (nitro-PAHs) derivatives have also been detected in some foods. This is worrying because these derivatives may be more toxic than PAHs. This study presents a new method for the determination of PAHs and their oxygenated and nitrated derivatives in coffee brew. The analytes were extracted by cold fiber solid phase microextraction (CF-SPME) with analysis by gas chromatography/mass spectrometry. The developed method presented good precision with intra-assay and inter-assay, ranged from 4.5 to 16.4%, and from 9.8 to 19.8%, respectively. Recovery ranged from 82.1 to96.3% and linearity showed good adjustment presenting determination coefficients (R2) from 0.980 to 0.999. The limits of quantification ranged from 0.025 to 0.224 μg L−1. The proposed method is simple, versatile, allows simultaneous extraction of PAHs, nitrated and oxygenated derivatives and was successfully applied to the analysis of commercial coffee samples. Benzo(k)fluoranthene, benzo(b)fluoranthene, pyrene, acenaphthylene and acenaphthene are the most abundant PAHs found in samples. In addition, 5,12-naphthacenequinone was the most abundant oxy-PAH and 1-nitropyrene was the most abundant nitro-PAH.

Thermocapillary instability of self-rewetting films on vertical fibers

The self-rewetting fluid has a quadratic temperature dependence of surface tension with a well-defined minimum, which is distinct from that of normal fluids whose surface tension decreases linearly with temperature. The instability of a self-rewetting film on a vertical hot or cold fiber is investigated using the long-wave asymptotic model, which discovers that the role of the thermocapillarity varies in three different regimes. In the normal regime, the behavior of this fluid is similar to that of a normal fluid while in another anomalous regime, it shows a reverse feature of instability. It is this reverse behavior that guarantees the potentials of this fluid in heat transfer applications. Transient numerical simulations are also performed to be compared with the linear theory and to explore the saturate states as well as the breakup for this special fluid. Apart from supporting the conclusions obtained in the linear analysis, noticeably, the numerical results predict a flatter saturate shape and a weaker breakup in the anomalous regime.

Effect of Strain Path on Texture Evolution in Cold Rolled Pure Titanium

The cold rolling texture evolution as a function of strain path in pure titanium with initial typical recrystallized texture has been studied using viscoplastic self-consistent simulations. Three different strain paths, namely unidirectional rolling, two-step cross rolling and multi-step cross rolling have been employed to investigate the effect of strain path change on the evolution of deformation texture. The simulation results indicate that the activation of predominant prismatic slip in unidirectional rolling sample results in the formation of commonly cold rolling fiber texture RD//<10-10> in pure titanium, whereas the increased activity of basal slip over that of prismatic slip is responsible for the strong ND//<hkil> fiber texture in the two cross rolled samples.

Chapter 3 - Molecular basis of peripheral innocuous cold sensitivity

Of somatosensory modalities cold is one of the more ambiguous percepts, evoking the pleasant sensation of cooling, the stinging bite of cold pain, and welcome relief from chronic pain. Moreover, unlike the precipitous thermal thresholds for heat activation of thermosensitive afferent neurons, thresholds for cold fibers are across a range of cool to cold temperatures that spans over 30°C. Until recently, how cold produces this myriad of biologic effects was unknown. However, recent advances in our understanding of cold mechanisms at the behavioral, physiologic, and cellular level have begun to provide insights into this sensory modality. The identification of a number of ion channels that either serve as the principal detectors of a cold stimulus in the peripheral nervous system, or are part of a differential expression pattern of channels that maintain cell excitability in the cold, endows select neurons with properties that are amenable to electric signaling in the cold. This chapter highlights the current understanding of the molecules involved in cold transduction in the mammalian peripheral nervous system, as well as presenting a hypothetic model to account for the broad range of cold thermal thresholds and distinct functions of cold fibers in perception, pain, and analgesia.

Determination of benzene, toluene, ethylbenzene and xylene in field and laboratory by means of cold fiber SPME equipped with thermoelectric cooler and GC/FID method

Abstract A simple and effective cooling device based on a thermoelectric cooler was applied to cool the SPME fiber. The device was used for quantitative extraction of aromatic hydrocarbons in the air. Several factors such as coating temperature, extraction temperature and relative humidity in the laboratory setting were optimized. Comparison of the results between the cold fiber SPME (CF-SPME) and NIOSH 1501 method on standard test atmosphere indicated a satisfactory agreement. The CF-SPME and SPME method were also compared. The results revealed that CF-SPME has the most appropriate outcome for the extraction of aromatic hydrocarbons from the ambient air. The cold fiber SPME technique showed good results for several validation parameters. Under the optimized conditions, the limits of detection (LOD) and the limits of quantification (LOQ) ranged from 0.00019 to 0.00033 and 0.0006 to 0.001 ng ml−1, respectively. The intra-day relative standard deviation (RSD) showed ranging from 4.8 to 10.5%.

Determination of BTEX in urine samples using cooling/heating-assisted headspace solid-phase microextraction

Excessive and uncontrolled exposures of the workers to benzene, toluene, ethylbenzene and xylene (BTEX) have currently raised great concerns among industrial hygienist all over the world. Therefore, the effective monitoring of such exposures is assumed to be of prime importance. A cold fiber solid-phase microextraction device based on a cooling capsule as a cooling unit and CO2 as a coolant was applied to quantitatively analyze BTEX in aqueous samples. A gas chromatography with flame ionization detection was recruited to analyze the target analytes, which had been identified according to their retention times. Several factors such as coating temperature, extraction time and temperature, sample volume and sodium content were optimized. Two modes of extraction, i.e., headspace (HS) and headspace cold fiber (HS-CF) in SPME, were investigated and compared under optimized conditions. The results revealed that HS-CF-SPME has the most appropriate outcome for the extraction of BTEX from aqueous samples. Under the optimized conditions, the calibration curves were linear within the range of 0.2–500 ng ml−1 and the detection limits were between 0.02 and 0.07 ng ml−1.The intraday relative standard deviations was lower than about 10%. The method was successfully applied to the determination of BTEX in urine samples with good recovery.

Improved Method to Assess Polycyclic Aromatic Hydrocarbons in Atmospheric Gas Particles in Belo Horizonte, Brazil

ABSTRACTThis article describes the development and validation of a solid-phase microextraction method using direct immersion and cold fiber (DI-CF-SPME) to collect samples in ambient air particulate matter and a gas phase to analyze 16 priority polycyclic aromatic hydrocarbons by gas chromatography mass spectrometry. This method has proven to yield good results for some validation parameters. Limits of detection and quantification ranged from 0.008 ng m−3 to 0.095 ng m−3 and from 0.020 ng m−3 to 0.101 ng m−3, respectively. The inter-assay precision shows a coefficient of variation ranging from 1.01% to 15.75%. The method was applied to the analysis of samples collected in 2014 and 2015 in the urban area of Belo Horizonte, located in southeastern Brazil. The samples were collected next to high-traffic routes and industrial regions using a PM10 (<10 μm) high-volume air sampler for 24-h periods. The total concentration of polycyclic aromatic hydrocarbon found in samples collected simultaneously in filter and foam were 8.53 ng m−3 and 18.58 ng m−3, respectively. Anthracene and fluoranthene showed the highest concentrations in the gas phase, whereas benzo(b)fluoranthene and benzo(ghi)perylene showed the highest levels in the particulate phase. A model based on principal component analysis was applied to identify possible anthropogenic sources of individual polycyclic aromatic hydrocarbons in 68 particulate matter samples. The results suggest that the main sources of these pollutants came from a combustion engine.

Use of exhaled air as an improved biomonitoring method to assess perchloroethylene short-term exposure

This paper shows the use of exhaled air as a biomonitoring method to assess perchloroethylene (PERC) environmental and occupational exposure. A sensitive, fast, and solvent free analytical method was developed to determine PERC in ambient and exhaled air of individuals occupationally exposed. The developed method used cold fiber solid phase microextraction (CF-SPME) as the sampling technique, and a standard permeation method to simulation of air matrix. The analysis were conducted by gas chromatography coupled to mass spectrometry (GC/MS). The methods were validated and were found to be precise, linear and sensitive for environmental and biological monitoring. The developed methods were applied to twenty-seven sampling points spread across Belo Horizonte city, Brazil, twenty four dry cleaners, an electroplating industry, a research laboratory, and an automotive paint preparation shop. The results of ambient air analyses ranging from 14.0 to 3205.0µgm−3 with median concentration of 599.0µgm−3. Furthermore, sampling of exhaled air of individuals occupationally exposed presented results ranging from 6.0 to 2635.0µgm−3 with median concentration of 325.0µgm−3. The strong correlation observed between ambient and exhaled air (r =0.930) demonstrates that exhaled air is a suitable biomarker for evaluating occupational exposure to PERC.

Environmental and biological determination of acrolein using new cold fiber solid phase microextraction with gas chromatography mass spectrometry.

Acrolein is a pollutant released daily to the indoor environment from different sources. The present study reports the development of a simple and sensitive cold fiber solid phase microextraction sampling method for the determination of acrolein in exhaled air and indoor air by gas chromatography mass spectrometry. O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine was used as derivatizing agent supported on a 65-μm polydimethylsiloxane-divinylbenzene SPME fiber. An acrolein permeation tube at 326.25ngmin-1 rate was used to generate gaseous standards. The method shows good results for main validation parameters. The limits of detection and quantification were 2.88 and 5.08μgm-3, respectively, for indoor analysis; and 2.40 and 3.79μgm-3, respectively, for exhaled air analysis. The precision showed standard deviation ranges from 6.00 to 8.00% for intra-assay analyses and from 8.00 to 10.00% for inter-assay analyses. After optimizing the conditions, analyses of real samples were performed on indoor environments contaminated by cigarette smoke, or heated oil, including pastry shops, restaurants, churros stands, and closed parking cars located in the city of Belo Horizonte, Brazil. Acrolein breaths of exposed people were also determined. A good Pearson correlation coefficient (r = 0.901) was observed between the concentration of acrolein in indoor air and exhaled air, allowing to propose acrolein breath as environmental exposure biomarker. Graphical Abstract Cold fiber solid phase microextraction gas chromatography/mass spectrometry.

Determination of Polycyclic Aromatic Hydrocarbons in Sediment by Pressure-Balanced Cold Fiber Solid Phase Microextraction.

An improved performance of the cold fiber solid phase microextraction (CF-SPME) technique was accomplished with the use of the pressure-balanced procedure. In order to obtain a pressure-balanced state during extraction at 200 °C, 7 mL of air volume was withdrawn from 10 mL commercial vials, while 15 mL was withdrawn from vials where 5 μL of diethylamine was added as a modifier/displacer. The benefits of the balanced system were demonstrated for determination of polycyclic aromatic hydrocarbons (PAHs) from solid matrixes, including sand and certified sediment samples. Results showed the pressure-balanced procedure enhanced the extraction efficiency of the method, especially for high volatility compounds, as the leakage of analytes was mitigated under sample temperature conditions of 200 °C. Analytical precision was also improved, with relative standard deviations (RSDs) ranging from 4% to 8% for all analytes under study. For the determination of PAHs in certified sediment samples, pressure-balanced CF-SPME yielded more accurate results in comparison to nonpressure-balanced CF-SPME. The proposed methodology provided the additional benefit of improved recoveries at lower pressures.

Methylene Blue promotes cortical neurogenesis and ameliorates behavioral deficit after photothrombotic stroke in rats

Ischemic stroke in rodents stimulates neurogenesis in the adult brain and the proliferation of newborn neurons that migrate into the penumbra zone. The present study investigated the effect of Methylene Blue (MB) on neurogenesis and functional recovery in a photothrombotic (PT) model of ischemic stroke in rats. PT stroke model was induced by photo-activation of Rose Bengal dye in cerebral blood flow by cold fiber light. Rats received intraperitoneal injection of either MB (0.5mg/kg/day) from day 1 to day 5 after stroke or an equal volume of saline solution as a control. Cell proliferative marker 5-bromodeoxyuridine (BrdU) was injected twice daily (50mg/kg) from day 2 to day 8 and animals were sacrificed on day 12 after PT induction. We report that MB significantly enhanced cell proliferation and neurogenesis, as evidenced by the increased co-localizations of BrdU/NeuN, BrdU/DCX, BrdU/MAP2 and BrdU/Ki67 in the peri-infarct zone compared with vehicle controls. MB thus effectively limited infarct volume and improved neurological deficits compared to PT control animals. The effects of MB were accompanied with an attenuated level of reactive gliosis and release of pro-inflammatory cytokines, as well as elevated levels of cytochrome c oxidase activity and ATP production in peri-infarct regions. Our study provides important information that MB has the ability to promote neurogenesis and enhance the newborn-neurons’ survival in ischemic brain repair by inhibiting microenvironmental inflammation and increasing mitochondrial function.