The Multisensor Array Based on Grown-On-Chip Zinc Oxide Nanorod Network for Selective Discrimination of Alcohol Vapors at Sub-ppm Range

We discuss the fabrication of gas-analytical multisensor arrays based on ZnO nanorods grown via a hydrothermal route directly on a multielectrode chip. The protocol to deposit the nanorods over the chip includes the primary formation of ZnO nano-clusters over the surface and secondly the oxide hydrothermal growth in a solution that facilitates the appearance of ZnO nanorods in the high aspect ratio which comprise a network. We have tested the proof-of-concept prototype of the ZnO nanorod network-based chip heated up to 400 °C versus three alcohol vapors, ethanol, isopropanol and butanol, at approx. 0.2–5 ppm concentrations when mixed with dry air. The results indicate that the developed chip is highly sensitive to these analytes with a detection limit down to the sub-ppm range. Due to the pristine differences in ZnO nanorod network density the chip yields a vector signal which enables the discrimination of various alcohols at a reasonable degree via processing by linear discriminant analysis even at a sub-ppm concentration range suitable for practical applications

UV-Light-Tunable p-/n-Type Chemiresistive Gas Sensors Based on Quasi-1D TiS\u3csub\u3e3\u3c/sub\u3e Nanoribbons: Detection of Isopropanol at ppm Concentrations

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 oC, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 oC reduces both the sensitivity and selectivity of the sensor array

UV-Light-Tunable p-/n-Type Chemiresistive Gas Sensors Based on Quasi-1D TiS3 Nanoribbons: Detection of Isopropanol at ppm Concentrations

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS(3)) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS(3) nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 °C, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 °C reduces both the sensitivity and selectivity of the sensor array

2D Molybdenum Carbide MXenes for Enhanced Selective Detection of Humidity in Air

2D transition metal carbides and nitrides (MXenes) open up novel opportunities in gas sensing with high sensitivity at room temperature. Herein, 2D Mo2CTx flakes with high aspect ratio are successfully synthesized. The chemiresistive effect in a sub-mu m MXene multilayer for different organic vapors and humidity at 10(1)-10(4) ppm in dry air is studied. Reasonably, the low-noise resistance signal allows the detection of H2O down to 10 ppm. Moreover, humidity suppresses the response of Mo2CTx to organic analytes due to the blocking of adsorption active sites. By measuring the impedance of MXene layers as a function of ac frequency in the 10(-2)-10(6) Hz range, it is shown that operation principle of the sensor is dominated by resistance change rather than capacitance variations. The sensor transfer function allows to conclude that the Mo2CTx chemiresistance is mainly originating from electron transport through interflake potential barriers with heights up to 0.2 eV. Density functional theory calculations, elucidating the Mo2C surface interaction with organic analytes and H2O, explain the experimental data as an energy shift of the density of states under the analyte's adsorption which induces increasing electrical resistance

Anthropometric characteristics of patients suffering from chronic cystitis

Introduction. With a depressingly high prevalence of chronic cystitis (it is believed that half of women suffer from acute cystitis at least once in their lives), there is still no clarity on this disease. We were unable to find any studies on the anthropometric characteristics of patients with chronic cystitis either in the domestic or in the English literature.Objective. To assess the anthropometric characteristics of patients with chronic recurrent cystitis.Material & methods. A prospective multicenter cohort study included 91 patients with symptoms of acute cystitis. All underwent anthropometric measurements, analyzed complaints, studied anamnesis morbi et vitae, performed a study on a gynecological chair; urine was sent for general analysis and bacteriological examination for nonspecific microflora with the determination of the sensitivity of the isolated pathogen to antimicrobial drugs. The patients answered questions about the Russian version of the Acute Cystitis Symptom Score (ACSS). A urethra and cervical canal smear was studied using the polymerase chain reaction method to identify the causative agents of sexually transmitted infections. The diagnosis was considered confirmed in the presence of leukocyturia, bacteriuria, and the sum of symptoms on the ACSS scale was 6 or more.Results. The duration of chronic recurrent cystitis was averaged at 7.1 ± 4.2 years. The age of the patients ranged from 18 to 49 years, averaging 28.9 ± 3.9 years. The height ranged from 150 cm to 178 cm, on average 165.9 ± 7.1 cm. The average weight was within the normal range: 64.2 ± 6.1 kg. However, the spread in the cohort by body weight was two-fold: from 42 to 86 kg. Overweight was found in five (5.5%) patients; two patients (2.2%), on the contrary, had a body weight deficit. When analyzing anthropometric indicators, along with the obvious ones (direct dependence of the duration of the disease on the age of the patient; direct dependence of the quality of life on the severity of symptoms), other statistically significant correlations were established: a positive relationship between age and weight, weight and duration of the disease.Conclusion. The analysis showed that overweight women respond to treatment worse, they have a longer history of cystitis. Neither typical symptoms nor ACSS score correlated with any of the anthropometric measures

The impact of life events on later life: A latent class analysis of the English longitudinal study of ageing

Objectives: Inequalities in life events can lead to inequalities in older age. This research aimed to explore associations between life events reported by older people and quality of life (QoL) and functional ability. Study Design: A latent class analysis (LCA) of the English Longitudinal Study of Ageing wave 3. Methods: Participants were grouped according to eight life events: parental closeness, educational opportunities in childhood, financial hardship, loss of an unborn child, bereavement due to war, involvement in conflict, violence, and experiencing a natural disaster. Linear and logistic regression were used to explore associations between these groups and the main outcomes of functional ability and QoL. Results: 7,555 participants were allocated to four LCA groups: “Few life events” (n=6,250), “Emotionally cold mother” (n=724), “Violence in combat” (n=274) and “Many life events” (n=307). Reduced QoL was reported in the “many life events” (coefficient -5.33, 95%CI -6.61 to -4.05), “emotionally cold mother” (-1.89, -2.62 to 1.15) and “violence in combat” (-1.95, -3.08 to -0.82) groups, compared to the “few life events” group. The “many life events” group also reported more difficulty with activities of daily living. Conclusions: Policies aimed at reducing inequalities in older age should consider events across the life course

Development of certain aspects of colloid chemistry and physical-chemical mechanics of disperse systems and materials in relation to stability of slopes and grades

In the article the motive force of the movement the particles in dispersed systems, which include soils, when load is just sole weight of the array was investigated. It is shown that the shearing force of the weight of the soil and the specific cohesion which taken into account in calculating the stability of slopes of embankments and landslides on the slopes, much less than real. The calculations showed that the electrophoretic mechanism is a very real explanation of the observed sliding the upper part of the slope

Independent diagnostic computer systems with the ability to restore operational characteristics of construction facilities

Progress in modern engineering devices favours the development of independent computer systems of intelligent change management of operational characteristics of construction facilities. The article deals with the continuous control system (monitoring) of the soil moisture. The capillary sensor applied provides a far higher accuracy in determining the moisture than it is achieved by discrete determination of soil electrical characteristics which depend on the concentration and proportion of salts dissolved in the soil as well as the particle-size distribution. A flowchart of the diagnostic system was developed; it does not only transfer the data from the sensors, processes them and informs the operator, but also gives the possibility of autonomous inclusion of mechanisms to eliminate the emerged damages. Thus, while monitoring the soil moisture of hillsides, embankments and cuts slopes it prevents their shifts and other damages