scholarly journals Fabrication of Gas-Sensor Chips Based on Silicon–Carbon Films Obtained by Electrochemical Deposition

Chemosensors ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 52 ◽  
Author(s):  
Tatiana N. Myasoedova ◽  
Mikhail N. Grigoryev ◽  
Nina K. Plugotarenko ◽  
Tatiana S. Mikhailova
Keyword(s):  
Gas Sensor ◽  
Electrochemical Deposition ◽  
Recovery Time ◽  
Carbon Film ◽  
High Sensitivity ◽  
Carbon Films ◽  
Silicon Carbon ◽  
Response And Recovery

In this study, we designed two types of gas-sensor chips with silicon–carbon film, doped with CuO, as the sensitive layer. The first type of gas-sensor chip consists of an Al2O3 substrate with a conductive chromium sublayer of ~10 nm thickness and 200 Ω/□ surface resistance, deposited by magnetron sputtering. The second type was fabricated via the electrochemical deposition of a silicon–carbon film onto a dielectric substrate with copper electrodes formed by photoelectrochemical etching. The gas sensors are sensitive to the presence of CO and CH4 impurities in the air at operating temperatures above 150 °C, and demonstrated p- (type-1) and n-type (type-2) conductivity. The type-1 gas sensor showed fast response and recovery time but low sensitivity, while the type-2 sensor was characterized by high sensitivity but longer response and recovery time. The silicon–carbon films were characterized by the presence of the hexagonal 6H SiC polytype with the impurities of the rhombohedral 15 R SiC phase. XRD analysis revealed the presence of a CuO phase.

scholarly journals Functionalized Reduced Graphene Oxide Thin Films for Ultrahigh CO2 Gas Sensing Performance at Room Temperature

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 623
Author(s):  
Monika Gupta ◽  
Huzein Fahmi Hawari ◽  
Pradeep Kumar ◽  
Zainal Arif Burhanudin ◽  
Nelson Tansu
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Functional Groups ◽  
Recovery Time ◽  
Room Temperature ◽  
Co2 Gas ◽  
Reduced Graphene ◽  
Response And Recovery

The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.

A facile method for preparation of porous nitrogen-doped Ti Ti3C2Tx MXene for highly responsive acetone detection at high temperature

2021 ◽  
pp. 2151043
Author(s):  
Zijing Wang ◽  
Fen Wang ◽  
Angga Hermawan ◽  
Jianfeng Zhu ◽  
Shu Yin
Keyword(s):  
Gas Sensor ◽  
Recovery Time ◽  
Gas Sensing ◽  
Three Dimensional ◽  
Gas Sensitivity ◽  
Nitrogen Doped ◽  
Dimensional Network ◽  
Potential Applications ◽  
Response And Recovery ◽  
Acetone Detection

Porous nitrogen-doped Ti3C2T[Formula: see text] MXene (N-TCT) with a three-dimensional network structure is synthesized via a simple sacrifice template method and then utilized as an acetone gas sensor. By introducing nitrogen atoms as heteroatoms into Ti3C2T[Formula: see text] nanosheets, some defects generate around the doped nitrogen atoms, which can greatly improve the surface hydrophilicity and adsorption capacity of Ti3C2T[Formula: see text] Mxene nanosheets. It resulted in the enhanced gas sensitivity, achieving a response value of about 36 ([Formula: see text]/[Formula: see text] × 100%) and excellent recovery time (9s) at 150[Formula: see text]C. Compared with the pure Ti3C2T[Formula: see text]-based gas sensor (381/92s), the response and recovery time are both obviously improved, and the response value increased by 3.5 times. The gas-sensing mechanism of the porous N-TCT is also discussed in detail. Based on the excellent gas sensitivity of porous N-TCT for highly responsive acetone detection at high temperatures, the strategy of nitrogen-doped two-dimensional nanomaterials can be extended to other nanomaterials to realize their potential applications.

Angiotensin II-induced thirst, but not sodium appetite, via AT1 receptors in organum cavum prelamina terminalis

1995 ◽  
Vol 268 (6) ◽  
pp. R1401-R1405 ◽  
Author(s):  
M. el Ghissassi ◽  
S. N. Thornton ◽  
S. Nicolaidis
Keyword(s):  
Angiotensin Ii ◽  
Salt Intake ◽  
High Sensitivity ◽  
Ang Ii ◽  
Nacl Solution ◽  
At1 Receptors ◽  
Sodium Appetite ◽  
Specific Antagonist

The angiotensin receptor specificity, with respect to fluid intake, of the organum cavum prelamina terminalis (OCPLT), a recently discovered discrete forebrain structure with high sensitivity to angiotensin II (ANG II), was investigated. ANG II (10 ng) microinjected into the OCPLT significantly increased water consumption but did not induce intake of a hypertonic (3%) NaCl solution. Losartan, an ANG II type 1 (AT1) receptor-specific antagonist, produced dose-related (1-100 ng) inhibition of ANG II-induced drinking. The ANG II type 2 receptor-specific antagonist CGP-42112A was ineffective. Intake of the 3% NaCl solution in response to microinjection of either of the antagonists into the OCPLT was never observed. These findings suggest that water intake produced by microinjection of ANG II into the OCPLT is mediated by AT1 receptors uniquely and that, in contrast to other regions of the brain, these receptors do not induce salt intake when stimulated by ANG II.

Thermal, optical and gas sensing properties of ZnO films prepared by different techniques

2018 ◽  
Vol 81 (1) ◽  
pp. 10101 ◽  
Author(s):  
Sonik Bhatia ◽  
Neha Verma ◽  
Munish Aggarwal
Keyword(s):  
Gas Sensor ◽  
Recovery Time ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Sol Gel ◽  
Hexagonal Wurtzite Structure ◽  
Effect Of Temperature ◽  
Zno Films ◽  
Sensing Properties ◽  
Response And Recovery

Nowadays, for environmental protection, the use of portable gas sensor is essential to detect toxic gases. To control this problem of hazardous gases, metal oxide based sensors plays a vital role. In this recent study, Indium (2 at.wt.%) doped ZnO films has been prepared by sol gel spin coating and thermal evaporation techniques on glass substrates. To enhance the sensing properties, indium (In) was used as dopant and their annealing effect of temperature was observed. Thermal properties have shown the fruitful result that prepared films are useful for the fabrication of solar cell. Electrical properties revealed that capacitance and dielectric constant decreases with increase in frequency. X-ray Diffraction showed hexagonal wurtzite structure highly oriented along (1 0 1) plane. Field emission scanning electron microscope of these synthesis films prepared by different have shown the morphology as nanospheres having size of the order of 40–60 nm. 2.0 at.% of indium as modifier resulted in highest response and selectivity towards 5 ppm of NO2 gas at different operating temperature (50–200 °C). Highest sensitivity was obtained at operating temperature of 150 °C. Prepared films have quick response and recovery time in the range of 14–27 s and 67–63 s. The highest response and recovery time of gas sensor was explained by valence ion mechanism.

scholarly journals УСКОРЕННЫЙ МЕТОД ПОДСЧЕТА МЕЗОФИЛЬНЫХ АЭРОБНЫХ И ФАКУЛЬТАТИВНО-АНАЭРОБНЫХ МИКРООРГАНИЗМОВ В ПТИЦЕПРОДУКТАХ

2019 ◽  
Author(s):  
S.S. Kozak ◽  
V.G. Semenov ◽  
R.T. Abdraimov ◽  
Y.A. Kozak
Keyword(s):  
Nutrient Medium ◽  
Classical Method ◽  
Raw Materials ◽  
High Sensitivity ◽  
Food Samples ◽  
Water Soluble ◽  
Gelling Agent ◽  
Comparative Tests

Проведена апробация и произведены сравнительные испытания тест-пластин, предназначенных для подсчета количества мезофильных аэробных и факультативно-анаэробных микроорганизмов (КМАФАнМ) в птицепродуктах. Лабораторные испытания включали в себя выявление диапазонов чувствительности тест-пластин для определения КМАФАнМ, подсчет процента их извлекаемости ( всхожести) с поверхности тест-пластин, а также проведение их сравнительных испытаний с помощью классического метода анализа. Тест-пластины типа 1 содержат готовую питательную среду, гель и тетразолиевый индикатор используются для подсчета КМАФАнМ в образцах пищевых продуктов, продовольственном сырье, а также при мониторинге окружающей среды. Тест-пластины типа 2 предназначены для экспрессного подсчета КМАФАнМ в пищевых продуктах и объектах внешней среды, содержат готовую питательную среду, водорастворимый желирующий агент, цветной индикатор. При сравнении чувствительности классических сред и тест-пластин типа 1 и типа 2 при определении КМАФАнМ была установлена высокая чувствительность как питательного агара, так и испытуемых тест-пластин. Для плотных сред она составляет не менее 0,1 мл суспензии из 6-го разведения. В наших исследованиях на всех чашках и тест-пластинах из 6 и 7 разведений выявлен рост типичных колоний, что свидетельствует о высокой чувствительности. Установлено, что процент извлекаемости на тест-пластинах хороший: на тест-пластинах типа 1 98,9, на тест-пластинах типа 2 86,8. При сравнительном исследовании классического метода и тест-пластин был получен хороший результат. Во всех случаях результаты исследований на КМАФАнМ тест-пластин сопоставим с классическим методом: процент извлекаемости апробируемого материала составил более 80, в некоторых случаях даже 100. Тест-пластины для определения КМАФАнМ просты в использовании, надежны, имеют длительный срок хранения (1 год), с их применением уменьшаются сроки проведения анализа, уменьшается трудоемкость исследований.Approbation and comparative tests of test-plates designed to count the number of mesophilic aerobic and facultative anaerobic microorganisms (NMAFAnM) in poultry products were carried out. Laboratory tests included identifying the sensitivity ranges of test plates for determining NMAFAnM, calculating the percentage of their recoverability ( germination) from the surface of the test-plates, as well as conducting their comparative tests using the classical analysis method. Type 1 test-plates contain ready-made nutrient medium, gel and tetrazolium indicator they are used to calculate NMAFAnM in food samples, food raw materials, and also when monitoring the environment. Type 2 test-plates are intended for express counting of NMAFAnM in food products and environmental objects they contain ready-made nutrient medium, a water-soluble gelling agent and a color indicator. When comparing the sensitivity of classical media and type 1 and type 2 test-plates when determining NMAFAnM, a high sensitivity of both nutrient agar and test test-plates was established. For solid media, it is at least 0.1 ml of a suspension of 6 dilutions. In our studies, the growth of typical colonies was revealed on all plates and test-plates from 6 and 7 dilutions, which indicates high sensitivity. The recovery rate on the test-plates was found to be good: 98.9 on type 1 test-plates and 86.8 on type 2 test-plates. In a comparative study of the classical method and test-plates, a good result was obtained. In all cases, the results of studies on NMAFAnM test-plates are comparable with the classical method: the percentage of extractability of the tested material was more than 80, in some cases even 100. Test-plates for determining NMAFAnM are easy to use, reliable, have a long shelf life (1 year), with their use, the analysis time is reduced, and the complexity of research is reduced.

scholarly journals No additional value of conventional and high-sensitivity cardiac troponin over clinical scoring systems in the differential diagnosis of type 1 vs. type 2 myocardial infarction

2018 ◽  
Vol 56 (5) ◽  
pp. 702-709 ◽  
Author(s):  
Luciano Consuegra-Sánchez ◽  
Juan José Martínez-Díaz ◽  
Luis García de Guadiana-Romualdo ◽  
Samantha Wasniewski ◽  
Patricia Esteban-Torrella ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Troponin T ◽  
Characteristic Curve ◽  
High Sensitivity ◽  
St Segment ◽  
Clinical Scoring

AbstractBackground:The distinction of type 1 and type 2 myocardial infarction (MI) is of major clinical importance. Our aim was to evaluate the diagnostic ability of absolute and relative conventional cardiac troponin I (cTnI) and high-sensitivity cardiac troponin T (hs-cTnT) in the distinction between type 1 and type 2 MI in patients presenting at the emergency department with non-ST-segment elevation acute chest pain within the first 12 h.Methods:We measured cTnI (Dimension Vista) and hs-cTnT (Cobas e601) concentrations at presentation and after 4 h in 200 patients presenting with suspected acute MI. The final diagnosis, based on standard criteria, was adjudicated by two independent cardiologists.Results:One hundred and twenty-five patients (62.5%)were classified as type 1 MI and 75 (37.5%) were type 2 MI. In a multivariable setting, age (relative risk [RR]=1.43, p=0.040), male gender (RR=2.22, p=0.040), T-wave inversion (RR=8.51, p<0.001), ST-segment depression (RR=8.71, p<0.001) and absolute delta hs-cTnT (RR=2.10, p=0.022) were independently associated with type 1 MI. In a receiver operating characteristic curve analysis, the discriminatory power of absolute delta cTnI and hs-cTnT was significantly higher compared to relative c-TnI and hs-cTnT changes. The additive information provided by cTnI and hs-cTnT over and above the information provided by the “clinical” model was only marginal.Conclusions:The diagnostic information provided by serial measurements of conventional or hs-cTnT is not better than that yielded by a simple clinical scoring model. Absolute changes are more informative than relative troponin changes.

P1730Serial high-sensitivity troponin I measurements to discriminate type 2 from type 1 myocardial infarction

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
D A Psyrakis ◽  
J Bormann ◽  
B Von Jeinsen ◽  
J S Wolter ◽  
M Weferling ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Troponin I ◽  
High Sensitivity ◽  
High Morbidity ◽  
Absolute Change ◽  
Coronary Syndrome ◽  
High Sensitivity Troponin ◽  
Rule Out

Abstract Background Acute myocardial infarction (MI) is associated with high morbidity and mortality. A robust differentiation between type 1 and type 2 MI (T1/T2MI) has prognostic and therapeutic implications. We investigated whether serial high-sensitivity cardiac troponin I measurements could reliably discriminate T1MI from T2MI in patients presenting with a non-ST elevation myocardial infarction (NSTEMI). Methods We used data from a prospective acute coronary syndrome biomarker registry of patients with suspected MI that presented at or were transferred to one of two study centres. Here, we analysed an unselected group of 265 NSTEMI patients (67.2% males). Blood was drawn on admission and after 3 hours. High-sensitivity troponin I (hs-cTnI) was measured in frozen samples by a technician blinded to patient characteristics. T1MI or T2MI was defined as the gold-standard study diagnosis by two independent cardiologists based on all available data according to the Third Universal Definition of MI. Results A diagnosis of T2MI was made in 55 patients (20.8%) in the NSTEMI cohort. T2MI patients did not differ from T1MI patients regarding age, gender, traditional risk factors, or percentage of those with a history of coronary artery disease. Median baseline hs-cTnI levels were higher in T1MI (436.25; IQR 63.7–1918.8 ng/L) than in T2MI patients (48.4; IQR 11.7–305.9 ng/L; p<0.001). Absolute change in hs-cTnI concentration between 0 and 3 h was greater in T1MI than in T2MI patients with Dhs-cTnI 93.6 ng/L (IQR 13.5–815.3 ng/L) vs. 20.4 ng/L (IQR 2.5–106.5 ng/L) (p<0.001). hs-cTnI yielded an area under the receiver operator characteristics (AUROC) curve for identifying T2MI at baseline of 0.71 (IQR 0.64–0.79) and after 3 h of 0.7 (IQR 0.61–0.78).Dhs-cTnI was associated with an AUROC of 0.68 (IQR 0.6–0.76). Regarding a rule-out approach, Youden-optimized cut-offs for hs-cTnI at baseline as well as for the absolute change in hs-cTnI concentration were calculated (186.5 ng/L; 154.4 ng/L). Use of these two criteria yielded a sensitivity of 89% (78–96%) and a negative predictive value of 95% (89–98%) to exclude T2MI. 49 of 55 T2MI patients would have been ruled out using this algorithm. Conclusion Our data show that hs-cTnI concentrations differ between patients presenting with T1 and T2MI. The concentration of hs-cTnI and its change over time has the potential to rule out T2MI and therefore to identify patients who might benefit from an early invasive management. The differentiation between T1MI and T2MI by using hs-cTnI is nevertheless challenging, and further research on specific algorithms is needed. Acknowledgement/Funding 3German Center for Cardiovascular Research (DZHK), Partnersite Rhein Main, Bad Nauheim, Germany

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