Hydrogen Gas Response of Zn1 – xAgxOy and Cu1 – xZnxOy Nanostructured Films

Detection of hydrogen gas in industry, biomedical systems and combustion systems is important for safety reasons. Silver doping in zinc oxide and zinc doping in copper oxide were investigated to obtain improved hydrogen sensing performances for sensors. Samples were grown by chemical method and studied by X-ray diffraction, SEM and sensorial techniques. For selectivity study samples were exposed to hydrogen, methane and ethanol gases. Were found growth and annealing regimes which allow us fabrication of faster and more selective gas sensors based on Zn1-xAgxOy nanostructured films and nanocrystallite Cu1-xZnxOy films with respect to 100 ppm H2

Causes of unfavorable evolution of pancreatic trauma

Catedra de chirurgie nr. 1 “Nicolae Anestiadi”, Universitatea de Stat de Medicină și Farmacie ”Nicolae Testemițanu”, IMSP Institutul de Medicină Urgentă, Laboratorul Chirurgie Hepato-Pancreato-Biliară, Chișinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Rezultatele tratamentului chirurgical în traumatismul pancreatic (TP) nu sunt considerate satisfăcătoare din cauza persistenței mortalității cu o frecvență de 13,8-39,4%. Complicația specifică - pancreatita acută posttraumatică (PAPT) se dezvoltă practic după fiecare intervenție chirurgicală cu o frecvența de 25,9-85,7%. Scopul: Analiza cauzelor rezultatelor nefavorabile în tratamentul TP. Material și metode: S-au studiat retrospectiv rezultatele tratamentului chirurgical a 70 pacienți cu TP, și anume complicațiile postoperatorii și letalitatea specifică și nespecifică. Criteriile de includere: vârsta >18 ani și intervenția urgentă; de excludere - decedații 24 ore . Rezultate: În perioada postoperatorie la 48 pacienți au fost depistate complicații specifice, cele mai frecvente fiind pancreonecroza (23 pts), PAPT interstițială și fistulele pancreatice (respectiv câte 11 pts.). Peste 48 ore au decedat 14 pacienți. Letalitatea specifică a constituit 9,6%, nespecifică - 12,4%. În dependență de intervențiile efectuate, complicațiile specifice și letalitatea au fost mai scăzute la drenarea închisă a BO, intervențiile fiind efectuate în gr. I-II de leziune vs gr. III-V (62,2% și 5,3% vs 85,7% și 42,9%). La prezența hemoragiilor s-a stabilit, că suturarea ermetică a țeusuturilor pancreatice a majorat frecvența complicațiilor specifice și letalității vs suturarea neermetică (91,6% și 16,3% vs 60,8% și 9,2%). Administrarea tratamentul medicamentos pentru PAPT, mai ales cu includerea Sandostatinei a diminuat rata complicațiilor și letalității specifice în comparație cu neadministrarea preparatului (56,5% și 4,7% vs 83,2% și 12,3%). Concluzii: Evoluția nefavorabilă a TP este urmare a suturării ermetice a plăgilor, drenării incorecte a BO și omiterii profilaxiei medicamentoase.Background: The outcomes of the surgical treatment in pancreatic trauma (PT) are not considered satisfactory because of the persistence of a high mortality rate, reaching 13,8-39,4%. The specific complication is posttraumatic acute pancreatitis (PTAP) that it develops after each surgical intervention in practice with a frequency between 25,9 and 85,7%. Aim of the study: Analysis of causes unfavorable results (outcomes) in the treatment of pancreatic treatment Methods and materials: The results of surgical treatment were retrospectively evaluated in 70 patients with pancreatic trauma according to (by) postinterventional complications and specific/non-specific lethality. Inclusion criteria were: age greater than 18 years and emergency surgery. Exclusion criteria were: died patients within 48 hours after hospitalization and hospitalization greater than 24 hours. Results: During the postoperative period specific complications were found in 48 patients, the most common being pancreonecrosis in 23 patients, PTAP interstitial and pancreatic fistula in 11 patients, respectively. After 48 hours 14 patients died. Specific lethality was 9.6% and non-specific lethality - 12.4%. Depending on the performed intervention, specific complications and lethality were lowered to the closed drainage of omental bursa (OB), the interventions being made in gr. I-II of lesions vs gr. III-V (62,2% and 5,3% vs 85,7% and 42,9%). In the presence of haemorrhages, it was established that the hermetic suture of pancreatic tissues increased the frequency of specific complications and lethality versus non-ermetic suture (91,6% și 16,3% vs 60,8% și 9,2%). Administration of drug therapy in PTAP, especially with the including of Sandostatin, reduced the rate of complications and specific lethality instead of non-administration of the medicine (56,5% și 4,7% vs 83,2% și 12,3%). Conclusions: The unfavorable evolution of PT is due to ermetic suturing of wounds, incorrect drainage of OB and omission of drug prophylaxis

Ethanol Sensing Performances of Zinc-doped Copper Oxide Nano-crystallite Layers

The synthesis via chemical solutions (aqueous) (SCS) wet route is a low-temperature and cost-effective growth technique of high crystalline quality oxide semiconductors films. Here we report on morphology, chemical composition, structure and ethanol sensing performances of a device prototype based on zincdoped copper oxide nanocrystallite layer. By thermal annealing in electrical furnace for 30 min at temperatures higher than 550 ˚C, as-deposited zinc doped Cu2O samples are converted to tenorite, ZnxCu1-xOy, (x=1.3wt%) that demonstrate higher ethanol response than sensor structures based on samples treated at 450 ˚C. In case of the specimens after post-growth treatment at 650 ˚C was found an ethanol gas response of about 79 % and 91 % to concentrations of 100 ppm and 500 ppm, respectively, at operating temperature of 400 ˚C in air

Hydrogen Gas Response of Zn1 – xAgxOy and Cu1 – xZnxOy Nanostructured Films

Detection of hydrogen gas in industry, biomedical systems and combustion systems is important for safety reasons. Silver doping in zinc oxide and zinc doping in copper oxide were investigated to obtain improved hydrogen sensing performances for sensors. Samples were grown by chemical method and studied by X-ray diffraction, SEM and sensorial techniques. For selectivity study samples were exposed to hydrogen, methane and ethanol gases. Were found growth and annealing regimes which allow us fabrication of faster and more selective gas sensors based on Zn1-xAgxOy nanostructured films and nanocrystallite Cu1-xZnxOy films with respect to 100 ppm H2

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Nanomaterials for highly selective and sensitive sensors toward specific gas molecules of volatile organic compounds (VOCs) are most important in developing new-generation of detector devices, for example, for biomarkers of diseases as well as for continuous air quality monitoring. Here, we present an innovative preparation approach for engineering sensors, which allow for full control of the dopant concentrations and the nanoparticles functionalization of columnar material surfaces. The main outcome of this powerful design concept lies in fine-tuning the reactivity of the sensor surfaces toward the VOCs of interest. First, nanocolumnar and well-distributed Ag-doped zinc oxide (ZnO:Ag) thin films are synthesized from chemical solution, and, at a second stage, noble nanoparticles of the required size are deposited using a gas aggregation source, ensuring that no percolating paths are formed between them. Typical samples that were investigated are Ag-doped and Ag nanoparticle-functionalized ZnO:Ag nanocolumnar films. The highest responses to VOCs, in particular to (CH3)2CHOH, were obtained at a low operating temperature (250 °C) for the samples synergistically enhanced with dopants and nanoparticles simultaneously. In addition, the response times, particularly the recovery times, are greatly reduced for the fully modified nanocolumnar thin films for a wide range of operating temperatures. The adsorption of propanol, acetone, methane, and hydrogen at various surface sites of the Ag-doped Ag8/ZnO(0001) surface has been examined with the density functional theory (DFT) calculations to understand the preference for organic compounds and to confirm experimental results. The response of the synergistically enhanced sensors to gas molecules containing certain functional groups is in excellent agreement with density functional theory calculations performed in this work too. This new fabrication strategy can underpin the next generation of advanced materials for gas sensing applications and prevent VOC levels that are hazardous to human health and can cause environmental damages

Nanomechanics of individual aerographite tetrapods

R.A., O.L. and K.S. would like to thank the German Research Foundation (DFG) for the financial support under schemes AD 183/17-1 and SFB 986-TP-B1, respectively, and the Graphene FET Flagship. R.M. and D.E. would like to thank for financial support from Latvian Council of Science, no. 549/2012. N.M.P. is supported by the European Research Council (ERC PoC 2015 SILKENE no. 693670) and by the European Commission H2020 under the Graphene Flagship (WP14 ‘Polymer Composites’, no. 696656) and under the FET Proactive (‘Neurofibres’ no. 732344). S.S. acknowledges support from SILKENE

Synthesis, Characterization And Dft Studies Of Zinc-Doped Copper Oxide Nanocrystals For Gas Sensing Applications

Due to their unique properties, p-type copper oxide nanostructures have demonstrated promising potential for various applications, especially for the detection of ethanol vapour and other volatile organic compounds (VOCs). In this work a simple and cost-effective synthesis from chemical solutions (SCS) at low temperatures (≤80 °C) and rapid thermal annealing (RTA) process were used to grow zinc-doped copper oxide (ZnxCu1-xOy) nanostructures. The structural, morphological, vibrational, chemical, electronic and sensorial characteristics of ZnxCu1-xOy nanocrystallite layers obtained by using such an efficient approach based on both, the SCS and RTA processes, have been studied. The investigations demonstrated the possibility to tune sensitivity from VOC to H2, as well as an improved response and high selectivity with respect to hydrogen gas for ZnxCu1-xOy nano-crystalline thin films with x = 0.03. Density functional theory calculations showed that the charge transfer together with changes in the Fermi level facilitate H2 gas sensing, which is further enhanced by Zn doping. Hydrogen gas sensing with a high response and selectivity using p-type hybrid semiconductor nanostructures has been reported. An improved stability in humid air was observed by exposure of doped samples to rapid thermal annealing process for the first time. The experimental and calculation results provide an alternative to sensitive and selective detection of ethanol and hydrogen gases, which would be of particular benefit in the area of public security, industrial and environmental applications

Uv Radiation And Ch4 Gas Detection With A Single Zno:Pd Nanowire

There is an increasing demand for sensors to monitor environmental levels of ultraviolet (UV) radiation and pollutant gases. In this work, an individual nanowire of Pd modified ZnO nanowire (ZnO:Pd NW) was integrated in a nanosensor device for efficient and fast detection of UV light and CH4 gas at room temperature. Crystalline ZnO:Pd nanowire/nanorod arrays were synthesized onto fluorine doped tin oxide (FTO) substrates by electrochemical deposition (ECD) at relative low-temperatures (90 °C) with different concentrations of PdCl2 in electrolyte solution and investigated by SEM and EDX. Nanodevices were fabricated using dual beam focused electron/ion beam (FIB/SEM) system and showed improved UV radiation response compared to pristine ZnO NW, reported previously by our group. The UV response was increased by one order in magnitude (∼ 11) for ZnO:Pd NW. Gas sensing measurements demonstrated a higher gas response and rapidity to methane (CH4 gas, 100 ppm) at room temperature, showing promising results for multifunctional applications. Also, due to miniature size and ultra-low power consumption of these sensors, it is possible to integrate them into portable devices easily, such as smartphones, digital clock, flame detection, missile lunching and other smart devices

Detectors Based On Pd-Doped And Pdo-Functionalized Zno Nanostructures

In this work, zinc oxide (ZnO) nanostructured films were grown using a simple synthesis from chemical solutions (SCS) approach from aqueous baths at relatively low temperatures (\u3c 95°C). The samples were doped with Pd (0.17 at% Pd) and functionalized with PdO nanoparticles (NPs) using the PdCl2 aqueous solution and subsequent thermal annealing at 650°C for 30 min. The morphological, micro-Raman and optical properties of Pd modified samples were investigated in detail and were demonstrated to have high crystallinity. Gas sensing studies unveiled that compared to pure ZnO films, the Pd-doped ZnO (ZnO:Pd) nanostructured films showed a decrease in ethanol vapor response and slight increase in H2 response with low selectivity. However, the PdO-functionalized samples showed excellent H2 gas sensing properties with possibility to detect H2 gas even at room temperature (gas response of ∼ 2). Up to 200°C operating temperature the samples are highly selective to H2 gas, with highest response of ∼ 12 at 150°C. This study demonstrates that surface functionalization of n-ZnO nanostructured films with p-type oxides is very important for improvement of gas sensing properties

Detectors based on Pd-doped and PdO-functionalized ZnO nanostructures

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