Formaldehyde Vapor Research Articles

Adsorption dynamics of gaseous toluene with and without formaldehyde and water vapors on composites of UiO-66-NH2 and microporous carbon

To improve the adsorption capacity/selectivity of activated carbon (AC) against diverse volatile organic compounds (VOCs), a series of AC-based composites have been prepared with UiO-66-NH2 (U6N) and coded as AC-U6Nx (x = 1–20 wt/wt%). The adsorption potential of AC-U6Nx is evaluated against toluene in relation to the effects of composite compositions and the presence of competing feed gases/vapors (e.g., formaldehyde (FA) and water vapor). Although AC-U6N(1%) adsorbs toluene preferentially over FA, the selectivity factor of the former decreases from 6.4 to 2.63 as the x value increases from 1 to 20 wt%. This indicates the crucial role of U6N-NH2 groups in active capturing of FA over toluene through Schiff-base adsorption mechanism. Interestingly, the partition coefficient (PC100%: 0.045 ± 0.004 mol kg−1 Pa−1) of AC-U6N(1%) for 100 ppm FA remains nearly constant across varying toluene levels (1–100 ppm), suggesting the preferential occupation of active sites by FA (pore-filling). The contrasting role of relative humidity (RH) is also evidenced, as AC-U6N(1%), exhibits the highest capacity for toluene and FA under dry (0 % RH) and humid (20 % RH) conditions, respectively. The adsorption behavior of VOC on AC-U6N(1%) surface active sites (e.g., graphitic basal planes, NH2, COO–, and Zr sites) is predictable with a good fit of experimental data to the Freundlich isotherm and pseudo-second-order (PSOM) kinetic models. A density functional theory (DFT) simulation supports the enhancement of toluene adsorption on the interface of AC and U6N-based systems. Overall, this work offers practical guidelines for the construction of advanced functional adsorbents against diverse VOCs under both competitive and non-competitive conditions.

Structure, Properties and Degradation of Self-Assembled Fibrinogen Nanofiber Scaffolds.

Self-assembled fibrinogen nanofibers are promising candidates for skin tissue engineering due to their biocompatibility and ability to mimic the native blood clot architecture. Here, we studied the structure-property relationship and degradation of rehydrated fibrinogen nanofibers prepared by salt-induced self-assembly, focusing on the effect of scaffold layering, cross-linking time and freeze-drying. Optimal fiber stability was achieved with cross-linking by formaldehyde (FA) vapor, while treatment with liquid aldehydes, genipin, EDC, and transglutaminase failed to preserve the nanofibrous architecture upon rehydration. Scaffold layering did not significantly influence the mechanical properties but changed the scaffold architecture, with bulk fiber scaffolds being more compact than layered scaffolds. Freeze-drying maintained the mechanical properties and interconnected pore network with average pore diameters around 20 μm, which will enhance the storage stability of self-assembled fibrinogen scaffolds. Varying cross-linking times altered the scaffold mechanics without affecting the swelling behavior, indicating that scaffold hydration can be controlled independently of the mechanical characteristics. Cross-linking times of 240 min increased scaffold stiffness and decreased elongation, while 30 min resulted in mechanical properties similar to native skin. Cross-linking for 120 min was found to reduce scaffold degradation by various enzymes in comparison to 60 min. Overall, after 35 days of incubation, plasmin and a combination of urokinase and plasminogen exhibited the strongest degradative effect, with nanofibers being more susceptible to enzymatic degradation than planar fibrinogen due to their higher specific surface area. Based on these results, self-assembled fibrinogen fiber scaffolds show great potential for future applications in soft tissue engineering that require controlled structure-function relationships and degradation characteristics.

Emerging 2D nanoscale metal oxide sensor: semiconducting CeO2nano-sheets for enhanced formaldehyde vapor sensing.

Herein, we fabricated nanoscale 2D CeO2sheet structure to develop a stable resistive gas sensor for detection of low concentration (ppm) level formaldehyde vapors. The fabricated CeO2nanosheets (NSs) showed an optical band gap of 3.53 eV and cubic fluorite crystal structure with enriched defect states. The formation of 2D NSs with well crystalline phases is clearly observed from high-resolution transmission electron microscope (HRTEM) images. The NSs have been shown tremendous blue-green emission related to large oxygen defects. A VOC sensing device based on fabricated two-dimensional NSs has been developed for the sensing of different VOCs. The device showed better sensing for formaldehyde compared with other VOCs (2-propanol, methanol, ethanol, and toluene). The response was found to be 4.35, with the response and recovery time of 71 s and 310 s, respectively. The device showed an increment of the recovery time (71 s to 100 s) with the decrement of the formaldehyde ppm (100 ppm to 20 ppm). Theoretical fittings provided the detection limit of formaldehyde ≈8.86 ± 0.45 ppm with sensitivity of 0.56 ± 0.05 ppm-1. The sensor device showed good reproducibility with excellent stability over the study period of 135 d, with a deviation of 1.8% for 100 ppm formaldehyde. The average size of the NSs (≈24 nm) calculated from HRTEM observation showed lower value than the calculated Debye length (≈44 nm) of the charge accumulation during VOCs sensing. Different defect states, interstitial and surface states in the CeO2NSs as observed from the Raman spectrum and emission spectrum are responsible for the formaldehyde sensing. This work offers an insight into 2D semiconductor-based oxide material for highly sensitive and stable formaldehyde sensors.

Genotoxicity of Formaldehyde: Effect of Whole-Body Exposure on Polychromatic Erythrocyte/Normochromatic Erythrocyte Ratio in Male and Female Rats.

Every day, millions of individuals are exposed to formaldehyde (FA) due to its extensive presence and versatile use. Many in vivoand in vitroexperiments revealed that the mechanism of genotoxicity induced by FA exposure is complex yet toxicity upon whole-body exposure (WBE) to FA is less. As teachers, students, and skilled assistants in the health care sectors are also extensively exposed to FA vapors, it might result in genotoxicity. However, the effects of subchronic exposure to FA at low concentrations are not clear. Hence, analysis of the micronucleus (MN) was necessary to study the genetic toxicity triggered by FA in the bone marrow of male and female experimental rats. The present study is a gender- and duration of exposure-based assessment of the geno- and cytotoxicity in bone marrow cells of Wistar rats to study the effect of WBE to 10% FA on polychromatic erythrocytes/normochromatic erythrocytes (PCE/NCE) ratio and micronucleated polychromatic erythrocytes (MnPCE) in experimental rats. The obtained result clearly showed that WBE to FA for 60 days at concentrations between 1 and 1.1 ppm (0, 1, and 1.5 h) induced genotoxic effects in both male and female rats by altering the MnPCE% and significantly increasing the ratio of PCE/NCE (1.07 ± 0.23, 1.20 ± 0.20, 1.22 ± 0.14). The PCE/NCE ratio in male rats was lesser (0.98, 1.12, and 1.18) when compared with female rats (1.17, 1.29, and 1.26) with 0, 1, and 1.5 h exposure, respectively. Thus, the genetic/cellular sensitivity to FA differs among the sexes and also depends on the exposure duration.

Hematological and immunohistochemical changes in testes associated with exposure to the formaldehyde Vapor in male rats

Hematological and immunohistochemical changes in testes associated with exposure to the formaldehyde Vapor in male rats

New Architecture Based on Metal-Organic Frameworks and Spin Crossover Complexes to Detect Volatile Organic Compounds.

We present here the encapsulation of a spin crossover complex C1 [FeII(L)] (L: 4-amino-, 2-(2-pyridinylmethylene)hydrazide) inside MOF-808(Zr), a chemically robust Metal-Organic Framework. The compound C1⊂MOF-808 retains its crystallinity as well as a partial porosity compared to pristine MOF and shows solvatochromism under Volatile Organic compounds (VOCs) sorption associated to a spin state change of the guest complex. More specifically, this compound shows an interesting reversible color change under formaldehyde and formic acid vapor sorption and can therefore be considered as a new kind of optical VOCs chemosensor, opening new doors for developing a broad range of VOCs optical sensors.

Formaldehyde vapor-induced chronic tracheitis in relation to the expression of S-100 proteins

Background and objective: Formaldehyde is the most widely used chemical in daily life; thus, chronic exposure to formaldehyde has been shown to have adverse effects on different organs in humans and animals. Different of industries use formaldehyde including the medical, detergent, cosmetic, food, rubber, metal, wood, leather, petroleum, and agricultural industries and as a hydrogen sulfide scavenger in oil operations. This research was designed to investigate variable tracheal changes arising from chronic formaldehyde exposure by measuring different histomorphometric parameters in accordance with S-100 protein expression. Methods: In this experiment, twenty Wister rats were used, divided into the control group (n=10) and the experimental group (n=10). Animals in the experimental group had approximately 21 days of formaldehyde vapor 40ppm. At the end of the study tracheal samples were collected and used for histopathologic assessments and IHC staining. Results: In comparison to the control group, the experimental group revealed various histological lesions in tracheal structures from lining epithelium till adventitia including highest degrees and scores of; Epithelial necrosis, goblet cell hyperplasia, fibrosis in the submucosa, squamous metaplasia, chronic tracheitis and glandular changes. Results of IHC showed that the S-100 expression in the experimental group displayed higher percentages in different cells (epithelial cells, chondrocytes, and inflammatory cells) which were reported as strong intensity (3+), then moderate intensity (2+), and accompanied by weak intensity (1+), which revealed minimum percentages compared to the control-negative group in which the weak intensity (1+) recorded the highest percentages. Conclusion: Chronic exposure to formaldehyde causes significant histological changes that may lead to cancer induction. S-100 may appear as pro-inflammatory and proliferative marker, also S-100 expression associated with chondrocyte hypertrophy.

PH-based colorimetric detection of monofunctional aldehydes in liquid and gas phases

Abstract An ammonium chloride–Congo red (NH4Cl-CR) solution is presented as a potential sensing solution for aldehydes. Monofunctional aldehydes such as formaldehyde, acetaldehyde, benzaldehyde, and isobutyraldehyde caused changes in the pH of the sensing solution, producing a color transition from red-orange to violet to blue. This distinguished them from the other compounds, thereby acting as a qualitative test for the functional group. The NH4Cl-CR solution was also employed in making filter paper-based and silica gel-based sensors for formaldehyde and acetaldehyde vapors. These sensors responded positively towards the aldehyde gases through a color transition from pink to blue. The NH4Cl-CR mixture provides a simple and easy-to-handle reagent for the detection of both liquid and gaseous aldehydes which has potential applications in environmental monitoring.

Anti-competitive adsorption of gaseous benzene on hydrophilic microporous carbon in humid conditions

The adsorption capture of ambient volatile organic compounds (VOCs) is of practical importance for air quality management. Herein, unique anti-competitive adsorption behavior of benzene on a hydrophilic activated carbon (Procarb-900 (P900)) is evidenced in the presence of competing components (e.g., formaldehyde (FA) and/or moisture). Contrary to general expectations, the adsorption capacity of 10 Pa benzene (QB) onto P900 (30 mg) at the 99 % breakthrough level improves from 144.8 to 187 mg g−1 as the relative humidity (RH) increases from 0 to 25 %. Such pattern is maintained at 183.9 mg g−1 even at the relatively high RH of 50 %. Furthermore, QB exhibits a remarkable increase of 56.1 % (to 226.0 mg g−1) in the binary phase (100 ppm benzene plus 50 ppm FA) relative to its single phase (144.8 mg g−1). The kinetic studies confirm the occurrence of anti-competitive adsorption of benzene under humid conditions with the unusual decrease in rate constants at the elevated RHs (i.e., 25 and 50 %). The thermodynamic studies suggest the exothermic nature of benzene adsorption onto P900. The hydrophilicity of P900's outer surface promotes the preferential adsorption of polar FA and water vapor over non-polar benzene, which deforms the activated carbon texture and lowers the pore size distribution (PSD). The narrow PSD enhances benzene uptake in the complex systems due to the confinement effect. Overall, this study offers insights into the unique anti-competitive adsorption of non-polar VOCs (e.g., benzene) on hydrophilic microporous adsorbents in the presence of potential interferences such as polar water vapor and FA. These findings offer a guideline for the practical implementation of adsorption techniques for gaseous VOCs in humid conditions.

Fluorinated TiO2 Hollow Spheres for Detecting Formaldehyde under UV Irradiation.

The fluorinated titanium dioxide (F-TiO2) hollow spheres with varying F to Ti molar ratios were prepared by a simple one-step hydrothermal method followed by thermal processing. The diameter of the F-TiO2-0.3 hollow spheres with a nominal ratio of F:Ti = 0.3:1 was about 200-400 nm. Compared with the sensor based on pristine TiO2 sensing materials, the F-TiO2-0.3 sensor displayed an enhanced sensing performance toward gaseous formaldehyde (HCHO) vapor at room temperature under ultraviolet (UV) light irradiation. The F-TiO2-0.3 sensor demonstrated an approximately 18-fold enhanced response (1.56) compared to the pristine TiO2 sensor (0.085). The response and recovery times of the F-TiO2-0.3 sensor to 10 ppm HCHO were about 56 s and 64 s, respectively, and a limit-of-detection value of 0.5 ppm HCHO was estimated. The F-TiO2-0.3 sensor also demonstrated good repeatability and selectivity to HCHO gas under UV light irradiation. The outstanding HCHO gas-sensing properties of the F-TiO2-0.3 sensor were related to the following factors: the excitation effect caused by the UV light facilitated surface chemical reactions with analyte gas species; the hollow sphere structure provided sufficient active sites; and the surface fluoride (≡Ti-F) created additional chemisorption sites on the surface of the TiO2 material.

Integration of jackfruit seed-derived carbon dots and electronic nose for a sensitive detection of formaldehyde vapor

The preparation of carbon dots from jackfruit seeds through a pyrolysis method at 280℃ and their use for the detection of formaldehyde were reported. The as-prepared carbon dots showed a high fluorescence efficiency with a quantum yield of 12.7% and excellent photostability and dispersibility in aqueous solution with a zeta potential of ‒62.5 mV. The integration of carbon dot thin film and a home-made optical electronic nose system possessed sensitivity towards formaldehyde vapor with a detection limit of 24.7%v/v across a linear range of 25%v/v to 100%v/v. Furthermore, the sensor showed the highest sensitivity towards formaldehyde against other volatile organic compounds through a strong interaction between the carbonyl groups and the carbon dots. Additionally, principal component analysis (PCA) was conducted to achieve quantitative measurements of formaldehyde content in different formaldehyde volume ratios with substantial variance. Due to the significance of methanol as a typical chemical precursor for the industrial manufacturing of formaldehyde, the quantitative analytical method is essential to determining formaldehyde or methanol concentration. The sensing ability of carbon dot film-integrated electronic nose towards formaldehyde in formaldehyde/methanol mixtures was measured to be 10.74%v/v in a linear range of 25%v/v to 100%v/v. The PCA showed orderly linear combinations of the data set, which can be potentially utilized to analyze formaldehyde and methanol content in industrial processes. The results indicate the significant potential of carbon dots and optical electronic nose system as an effective formaldehyde sensing platform. Potential applications include the quantification of formaldehyde from methanol conversion and determination of methanol contaminant in formaldehyde.

Effects of Chemical Fixatives on Kinetic Measurements of Biomolecular Interaction on Cell Membrane.

Understanding the interaction between ligands and membrane proteins is important for drug design and optimization. Although investigation using live cells is desirable, it is not feasible in some circumstances and cell fixation is performed to reduce cell motion and degradation. This study compared the effects of five fixatives, i.e., formaldehyde vapor (FV), paraformaldehyde (PFA), acetone, methanol, and ethanol, on kinetic measurements via the LigandTracer method. We found that all five fixatives exerted insignificant effects on lectin-glycan interaction. However, antibody-receptor interaction is markedly perturbed by coagulant fixatives. The acetone fixation changed the binding of the anti-human epidermal growth factor receptor 2 (HER2) antibody to HER2 on the cell membrane from a 1:2 to a 1:1 binding model, while methanol and ethanol abolished the antibody binding possibly by removal of the HER2 receptors on the cell membrane. The capability of binding was retained when methanol fixation was performed at lower temperatures, albeit with a binding model of 1:1 instead. Moreover, whereas cell morphology does not exert a substantial impact on lectin-glycan interaction, it can indeed modify the binding model of antibody-receptor interaction. Our results provided insights into the selection of fixatives for cell-based kinetic studies.

Surface energy and stress driven growth of extremely long and high-density ZnO nanowires using a thermal step-oxidation process.

Formation of highly crystalline zinc oxide (ZnO) nanowires with an extremely high aspect ratio (length = 60 μm, diameter = 50 nm) is routinely achieved by introducing an intermediate step-oxidation method during the thermal oxidation process of thin zinc (Zn) films. High-purity Zn was deposited onto clean glass substrates at room temperature using a vacuum-assisted thermal evaporation technique. Afterwards, the as-deposited Zn layers were thermally oxidized under a closed air ambient condition at different temperatures and durations. Structural, morphological, chemical, optical and electrical properties of these oxide layers were investigated using various surface characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoemission spectroscopy (XPS). It was noticed that the initial thermal oxidation of Zn films usually starts above 400 °C. Homogeneous and lateral growth of the ZnO layer is usually preferred for oxidation at a lower temperature below 500 °C. One-dimensional (1D) asymmetric growth of ZnO started to dominate thermal oxidation above 600 °C. Highly dense 1D ZnO nanowires were specifically observed after prolonged oxidation at 600 °C for 5 hours, followed by short-step oxidation at 700 °C for 30 minutes. However, direct oxidation of Zn films at 700 °C resulted in ZnO nanorod formation. The formation of ZnO nanowires using step-oxidation is explained in terms of surface free energy and compressive stress-driven Zn adatom kinetics through the grain boundaries of laterally grown ZnO seed layers. This simple thermal oxidation process using intermittent step-oxidation was found to be quite unique and very much useful to routinely grow an array of high-density ZnO nanowires. Moreover, these ZnO nanowires showed very high sensitivity and selectivity towards formaldehyde vapour sensing against few other VOCs.

Mixed-ligand based water-stable Mn(II)-MOF for quick, sensitive, and reusable IFE-PET-RET facilitated detection of formaldehyde and Cr(VI)-oxoanions in real-field samples like food and industrial water: experimental and theoretical insights.

We report the luminescence-based detection of Group-1 carcinogen formaldehyde (FA) and Cr(VI)-oxoanions with a mesoporous Mn(II)-MOF (1), featuring a uninodal 4-c net topology and linear 1D square channels forming a polymeric 2D network. The Mn-MOF i.e., [Mn(phen)(hia)(H2O)]∞ was solvothermally constructed using π-conjugated, chelating phenanthroline (phen) and µ3-η2:η1 binding 5-hydroxyisophthalic acid (hia) ligands. The 2D rod-like crystallites of 1 demonstrated excellent phase purity, high thermal and photostability, and robustness under harsh conditions. The SCXRD and XPS studies established the structural framework and elemental composition, while the Hirshfeld surface analysis and NCI-RDG plot confirmed the presence of π-π stacking and weak interactions in 1. We explored the bright-blue emission of 1 for recyclable and fast-responsive (∼70 s) 'turn-off' detection of FA, with a low limit of detection (LOD) of 8.49 µM. Based on this, a 04-input-03-output molecular logic gate was proposed, which can be useful as a molecular switch for future applications. Furthermore, a unique experimental setup using the MOF film demonstrated ∼57% quenching upon exposure to FA vapor (an indoor VOC). Additionally, 1 exemplified itself as an efficient probe towards Cr(VI)-oxyanions, depicting LODs of 79 and 170 ppb, Stern-Volmer constants (KSV) of 16.13 × 104 and 12.73 × 104 M-1, and response times of ∼48 and ∼40 s for CrO42- and Cr2O72-, respectively. DFT calculations and specific wet-chemical investigations elucidated the FA detection to be triggered by photo-induced electron transfer (PET), while the Cr(VI)-sensing involved a combination of PET, the inner-filter effect (IFE), resonance energy transfer (RET), and electrostatic H-bonding interactions. The FA detection was validated using food samples (fish and meat) and wastewater specimens, achieving excellent recovery rates of ∼92-95%. Furthermore, the MOF's efficacy in recognizing the Cr(VI)-species in complex matrices (coal mine wastewater, sewage, and tap water) was investigated to yield high KSV values (3.10-5.17 × 104 and 2.16-7.03 × 104 M-1 for CrO42- and Cr2O72-), which demonstrated the probe's consistency and reliability.

Protective Effect of Garlic Oil Supplementation on Serum Sodium and Potassium Ions against Formaldehyde Induced Toxicity in Wistar Rats

The present experimental study was designed to investigate the protective effect of garlic oil against formaldehyde vapor induced toxicity on serum electrolytes namely sodium (Na+) and potassium (K+). Twenty four male rats were randomly divided into three groups (control set 1, experimental set 2 and experimental set 3). The control set 1 was fed with standard food without any exposure and garlic oil supplementation while experimental set 2 was exposed to 6 ppm formaldehyde vapors for one hour daily for 30 days and experimental set 3 was given garlic oil supplementation (1 ml/100 g b. wt.) after exposure to 6 ppm formaldehyde vapors for one hour daily for 30 days. A highly significant increase in serum sodium ion level and a highly significant decrease in serum potassium ion level was observed respectively after exposure to formaldehyde vapors (P<0.01), while a significant decrease in serum sodium ion level (P<0.05) and a highly significant increase in serum potassium ion level has been noticed respectively after supplementation of garlic oil in comparison to formaldehyde vapor exposed rats (P<0.01). Therefore, it is concluded that garlic oil has shown positive potential to detoxify the toxic effect of formaldehyde inhalation on serum electrolytes sodium Na+ and potassium K+.

Needle flower-like ZnO-based chemiresistive sensor for efficient detection of formaldehyde vapors

The development of a chemiresistive sensor that uses needle-flower-like ZnO to effectively detect formaldehyde vapors is highlighted in the paper. The hydrothermal process at low temperature was used to prepare the sensing material. The morphological and structural characteristics of the synthesized material were assessed using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Using a micropipette, the sensing material was transferred to the surface of the gold-based interdigitated electrodes to fabricate the device. The fabricated sensor was found to be more selective and sensitive to formaldehyde in the sensing study. The results showed an approximate response of 8 at 250 °C and 75 ppm formaldehyde. The lowest detection limit of the sensor was calculated as 480 ppb. The sensor has a great potential to monitor formaldehyde vapors in the indoor environment.

Сравнительная оценка токсичности и вирулицидных свойств дезинфектантов, применяемых при работе с вирусом SARS-CoV-2 в изолированных вирусологических лабораториях

The choice of disinfectants and their combinations for the final disinfection of the premises of «infectious» areas of laboratories of biosafety level 3–4, in which work is carried out with viruses with epidemic potential, is important for reducing the toxic effect of these disinfectants on personnel while maintaining 100?% disinfection efficiency. Purpose of the study: to study the toxicity of disinfectants of different groups for cell culture, to select a toxicity neutralizer, to study the virucidal activity of these disinfectants and their combinations against the SARS-CoV-2 virus. Materials and methods: experimental studies were carried out using the reference strain of coronavirus SARS-CoV-2, namely the hCoV-19/Australia/VIC01/2020 (AUS) strain (Wuhan variant), obtained from the State Collection of Causative Agents of Viral Infectious Diseases and Rickettsial Diseases, functioning on the basis of the Federal Budgetary Institution State Scientific Center for Virology and Biotechnology «Vector» of Rospotrebnadzor. The residual infectious activity of the virus was determined by titrating samples in cell culture. To conduct the research, we used a Vero E6 cell culture obtained from the Collection of Cell Cultures of the Federal Budgetary Institution of Scientific Research Center for Virology and Biochemistry «Vector» of Rospotrebnadzor in the form of a 2-day monolayer with a confluency of 95–100?%. Results. As a result of the studies, experimental data were obtained on the dynamics of the virucidal activity of different groups of disinfectants and their combinations against the SARS-CoV-2 virus. The degree of toxicity of disinfectants for Vero E6 cell culture is shown. Optimal combinations of disinfectants and a 40?% aqueous solution of formaldehyde (hereinafter referred to as formalin) have been selected, increasing its disinfection efficiency at an initial concentration halved, which can be used for final disinfection treatment of the premises of isolated virology laboratories conducting work with the SARS-CoV- coronavirus. Conclusion. The results obtained indicate that when using selected combinations of disinfectants to carry out final disinfection with formaldehyde vapors formed during the evaporation of formaldehyde as a result of its heating, a twofold decrease in the initial concentration of formalin is possible, leading to a decrease in its toxic effect on personnel, while maintaining 100?% efficiency disinfection. Keywords: disinfection, disinfectants, formaldehyde, SARS-CoV-2 coronavirus, disinfection efficiency, cytotoxicity.

ZnO quantum dots sensitized ZnSnO3 for highly formaldehyde sensing at a low temperature

Developing gas sensors for formaldehyde vapor detection is necessary. Metal oxide semiconductor (MOS) exhibited good formaldehyde sensing properties but with high working temperature and unsatisfactory selectivity. Herein, ZnSnO3 was sensitized by ZnO QDs modification for high-performance formaldehyde sensing at low working temperatures via simple immersion method. Meanwhile, SnO2 QDs instead of ZnO QDs was also modified on ZnSnO3 nanocubes. The result indicated both ZnO QDs and SnO2 QDs modification greatly improved gas sensing response and lower the working temperature of ZnSnO3 to formaldehyde. Whereas, the obtained ZnSnO3/ZnO QDs composite (ZSO/ZQD) containing 5 wt% ZnO QDs (ZSO/ZQD-0.05) showed a highest response value of 613.3–100 ppm formaldehyde at 70℃ with good reversibility and stability, which was nearly 20 times of bare ZnSnO3 and 6 times of SnO2 QDs modified ZnSnO3. The detection limit reached 100 ppb formaldehyde. The formaldehyde sensing performance of ZSO/ZQD-0.05 composite was checked in presence of simulated indoor pollutants. Its improved sensor performance was mainly attributed to ZnO QDs, which played roles in forming rich heterojunctions with ZnSnO3, increasing the surface area, and providing oxygen deficiency for formaldehyde sensing reaction. This provided an alternative way to improving the sensing properties of MOS by QDs modification.

Morphological changes in liver tissues of rats under the exposure of ecotoxicants and perinatal prophylaxis

BACKGROUND: The high sensitivity of the liver to chemicals is due to its leading role in their metabolism. During the biotransformation of ecotoxicants, highly reactive intermediate products may be formed and free radical oxidation may be initiated, which may result in liver damage.
 MATERIALS AND METHODS: The experiment was carried out on outbred white rats weighing 180250 g. A total of 50 animals were involved in the experiment. All animals were divided into 5 groups: control and 4 experimental ones. All rats in the experimental groups were subjected to inhalation exposure to gasoline and formaldehyde vapors. In the 1st (control) group only poisoning with ecotoxicants was used, in the 2nd group peptinsorbent (apple pectin) was used against the background of poisoning with ecotoxicants, in the 3rd group a membrane protector lemongrass, in the 4th group a beets, in the 5th experimental group peptinsorbent, membrane protector and beets. We examined pieces of liver and rats that were subjected to histological processing. Using a LEICA RM 2145 rotary microtome (Leica Microsystems, Germany), histological sections with a thickness of 58 m were prepared. Stained sections were examined and photographed using an Axio Imager Z1 light microscope (Carl Zeiss, Germany).
 RESULTS: The liver structure of rat pups born from female rats exposed to subchronic gasoline and formaldehyde poisoning throughout pregnancy has pronounced pathomorphological signs characteristic of hepatosis, turning into toxic hepatitis. The use of lemongrass, peptinsorbent and beets separately, along with intoxication of pregnant rats, somewhat reduced the degree of pathomorphological changes in the liver of born rat pups, but not dramatically. When using a combined mixture (apple pectin + membrane protector lemongrass + beets), the liver structure of the rat pups subsequently born was preserved relatively better than in the control group, with the exception of certain areas of the liver in which hemostasis and moderately pronounced dystrophic changes in hepatocytes were detected.
 CONCLUSIONS: The combined mixture (apple pectin + membrane protector lemongrass + beets) has a more pronounced hepatoprotective effect compared to the separate use of each of its constituent substances and is effective as a hepatoprotective agent for liver damage from ecotoxicants.

Pattern Recognition and Visual Detection of Aldehydes Using a Single ESIPT Dye.

The accurate discrimination and quantification of aldehydes is a worthy objective made challenging by their similar chemical reactivities. Considering the nucleophilic reaction mechanism between an aldehyde and a primary amine, it is reasonable to vary the reaction pH to manipulate the reactivity of aldehydes and the stability of the resulting Schiff base for analytical purposes. We have designed and synthesized three benzothiazole-based fluorescent molecules (BS1-BS3) containing an amino group substituted at the ortho-, meta-, and para-positions for aldehyde sensing. It was determined that only BS1 having an amino group at the ortho-position exhibits a significant fluorescence response in the presence of formaldehyde at a particular pH, whereas BS2 and BS3 gave negligible responses, indicating that the ESIPT process in BS1 should be responsible for the changes in its fluorescence. Accordingly, a pH-mediated sensor array BS1SA was constructed by dissolving BS1 in aqueous solvents with different pH values. BS1SA was found to be reliable for the discrimination of seven different aldehydes and identification of unknown aldehyde samples. Moreover, BS1 was successfully applied to prepare a fluorescent test paper for the visual detection of formaldehyde vapor.