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BACKGROUND Elevated preoperative lactate levels have been reported in patients admitted for resection of brain tumors. As histologic type and tumor grade have also been linked to lactate concentration, we hypothesized that preoperative lactate concentration in patients with brain tumors may be associated with tumor proliferation. We describe the relationship between preoperative plasma lactate levels, and the cell proliferation marker Ki-67 in brain tumor surgery. METHODS In this cross-sectional study, records of patients who underwent craniotomy between June 2017 and February 2018 at our Hospital were reviewed to select glioma and meningioma cases in which lactate concentrations in plasma and degree of cell proliferation were registered. Bivariable and linear regression analyses were used to assess the association between lactate concentrations and the Ki-67 index. RESULTS Lactate concentrations in plasma and Ki-67 index were available in 55 patients. Meningioma cases had a mean concentration of 1.2 (0.1) mmol/L compared to diffuse astrocytic and oligodendroglial tumours cases with 1.7 (0.1) mmol/L (p

We aimed to compare systemic and cerebral hemodynamics and coughing during emergence after pituitary surgery after endotracheal tube (ETT) extubation or after replacing ETT with a laryngeal mask airway (LMA). Patients were randomized to awaken with an ETT in place or after replacing it with an LMA. We recorded mean arterial pressure (MAP), heart rate, middle cerebral artery (MCA) flow velocity, regional cerebral oxygen saturation (SrO2), cardiac index, plasma norepinephrine, need for vasoactive drugs, coughing during emergence, and postoperative cerebrospinal fluid (CSF) leakage. The primary endpoint was postoperative MAP, secondary endpoints were SrO2 and coughing incidence. Forty-five patients were included. MAP was lower during emergence than at baseline in both groups. There were no significant between-group differences in blood pressure, nor in the number of patients that required antihypertensive drugs during emergence (ETT: 8 patients (34.8%) vs. LMA: 3 patients (14.3%), p = 0.116). MCA flow velocity was higher in the ETT group (e.g., mean (95% CI) at 15 min, 103.2 (96.3–110.1) vs. 89.6 (82.6–96.5) cm·s−1, p = 0.003). SrO2, cardiac index, and norepinephrine levels were similar. Coughing was more frequent in the ETT group (81% vs. 15%, p &lt, 0.001). CSF leakage occurred in three patients (13%) in the ETT group. Placing an LMA before removing an ETT during emergence after pituitary surgery favors a safer cerebral hemodynamic profile and reduces coughing. This strategy may lower the risk for CSF leakage.

Aerosol assisted chemical vapour deposited ZnO nanostructured films integrated into Si-based transducing platforms are modified with preformed Au nanoparticles (NPs) via impregnation. The morphological, structural, and chemical characterization of these films using different characterisation techniques shows the incorporation of well-distributed and stable Au nanoparticles (NPs) at the surface of ZnO. Photoactivated gas sensing tests at room temperature (RT) demonstrate enhanced sensitivity and better speed of response for the Au modified ZnO films (AuZn) providing 3 times higher response to ethanol and acetone as compared to the non-modified ZnO films (Zn).

A methodology based on the use of Electron Beam Lithography for contacting individual nanowires on top of non-flat micromembranes and microhotplates has been implemented, and the practical details have been exhaustively described. The different fabrication steps have been adapted to the substrate’s topology, requiring specific holders and conditions. The methodology is demonstrated on individual SnO2 nanowires, which, after fabrication, have been characterized as functional resistive gas nanosensors towards NH3 and benchmarked against similar devices fabricated using more conventional Dual Beam Focused Ion Beam techniques, demonstrating the superior properties of the here presented methodology, which can be further extended to other non-conventional suspended substrates and nanomaterials.

We report the growth of micrometer-sized In2O3 octahedral structures, which are next aligned in chains using dielectrophoresis on top of microhotplates with prepatterned electrodes and integrated heater to work as chemoresistive gas sensors. The devices are relatively fast (180 s), highly sensitive (response up to ∼256%), and selective toward NO2 in humid environments, showing little response to O2 and ethanol, and being completely insensitive to CO and CH4. The here-presented fabrication method can be easily extended as a cost-effective post-process in CMOS-compatible microhotplate fabrication and, thus, represents a promising candidate for indoor and outdoor air quality monitoring devices. Funding: This work has been partially supported by the Spanish Ministeriode Economía y Competitividad, through projects TEC2013-48147-C6 and TEC2016-79898-C6 (AEI/FEDER, EU) and by the Spanish Agencia Estatal de Investigación (AEI), through projects PID2019-107697RB-C41/AEI/10.13039/501100011033 and PID2019-107697RB-C42/AEI/10.13039/501100011033.

Background Maintaining adequate blood pressure to ensure proper cerebral blood flow (CBF) during surgery is challenging. Induced mild hypotension, sitting position or unavoidable intra-operative circumstances such as haemorrhage, added to variations in carbon dioxide and oxygen tensions, may influence perfusion. Several of these circumstances may coincide and it is unclear how these may affect CBF. Objective To describe the variation in transcranial Doppler and regional cerebral oxygen saturation (rSO2), as a surrogate of CBF, after cardiac preload and gravitational positional changes. Design Observational study. Setting Operating room at Hospital Clinic de Barcelona. Volunteers Ten healthy volunteers, white, both sexes. Interventions Measurements were performed in the supine, sitting and standing positions during hyperoxia, hypocapnia and hypercapnia protocols and after a Valsalva manoeuvre. Main outcome measures Cardiac index (CI), haemodynamic and respiratory variables, maximal and mean velocities (Vmax, Vmean) (transcranial Doppler) and rSO2 were acquired. Results were analysed using a generalised estimating equation technique. Results CI increases more than 16% after a preload challenge were not accompanied by differences in rSO2 or Vmax - Vmean. With positional changes, Vmean decreased more than 7% (P = 0.042) from the supine to the seated position. Hyperoxia induced a cerebral rSO2 increase more than 6% (P = 0.0001) with decreases in Vmax, Vmean and CI values more than 3% (P = 0.001, 0.022 and 0.001) in the supine and standing position. During hypocapnia, CI rose more than 20% from supine to seated and standing (P = 0.0001) with a 4.5% decrease in cerebral rSO2 (P = 0.001) and a decrease of Vmax - Vmean more than 24% in all positions (P = 0.001). Hypercapnia increased cerebral rSO2 more than 17% (P = 0.001), Vmax - Vmean more than 30% (P = 0.001) with no changes in CI. After a Valsalva manoeuvre, rSO2 decreased more than 3% in the right hemisphere in the upright position (P = 0.001). Vmax - Vmean decreased more than 10% (P = 0.001) with no changes in CI. Conclusion CBF changes in response to cerebral vasoconstriction and vasodilatation were detected with rSO2 and transcranial Doppler in healthy volunteers during cardiac preload and in different body positions. Acute hypercapnia had a greater effect on recorded brain parameters than hypocapnia.

© 2020 by the authors., This work presents the effect of magnesium (Mg) doping on the sensing properties of tin dioxide (SnO2) thin films. Mg-doped SnO2 films were prepared via a spray pyrolysis method using three doping concentrations (0.8 at.%, 1.2 at.%, and 1.6 at.%) and the sensing responses were obtained at a comparatively low operating temperature (160 °C) compared to other gas sensitive materials in the literature. The morphological, structural and chemical composition analysis of the doped films show local lattice disorders and a proportional decrease in the average crystallite size as the Mg-doping level increases. These results also indicate an excess of Mg (in the samples prepared with 1.6 at.% of magnesium) which causes the formation of a secondary magnesium oxide phase. The films are tested towards three volatile organic compounds (VOCs), including ethanol, acetone, and toluene. The gas sensing tests show an enhancement of the sensing properties to these vapors as the Mg-doping level rises. This improvement is particularly observed for ethanol and, thus, the gas sensing analysis is focused on this analyte. Results to 80 ppm of ethanol, for instance, show that the response of the 1.6 at.% Mg-doped SnO2 film is four times higher and 90 s faster than that of the 0.8 at.% Mg-doped SnO2 film. This enhancement is attributed to the Mg-incorporation into the SnO2 cell and to the formation of MgO within the film. These two factors maximize the electrical resistance change in the gas adsorption stage, and thus, raise ethanol sensitivity., This work was supported by the Spanish Ministry of Economy and Competitiveness via project TEC2016-79898-C6-1-R (AEI/FEDER, EU) and the ‘Ramón y Cajal’ Programme. Part of this research used the Czech CEITEC Nano Research Infrastructure, supported by MEYS (2016–2019).

In the present work, nanostructures of zeolitic imidazolate frameworks (ZIF-8 and ZIF-67) were combined to obtain a novel chemoresistive sensor, improving the response of ZIF-67 and facilitating measurement of ZIF-8 by decreasing the resistivity. The sensor detected concentrations as low as 10 ppm of toluene, ethanol, carbon monoxide, hydrogen and nitrogen dioxide, showing large resistance change. In the case of toluene and hydrogen for a 10 ppm concentration, the response of ZIFs combination based sensor was significantly higher than ZIF-67 based sensor; about 7.0 and 5.4 times, respectively.

In this paper, propagation of shear horizontal surface acoustic waves (SH-SAW) in nanoparticle layers was studied by means of dispersion acoustic theory in waveguides. These studies have allowed to obtainment of properties of nanoparticles layers, such as shear stiffness modulus. In addition, the numerical analysis of multi-guiding layers have allowed for the design of an innovative, simple and inexpensive gas sensor based on elastic properties variation of the nanoparticles layers due to their interaction with gases. Each sensor has been prepared by coating a uniform layer of nanostructured indium tin oxide (ITO) nanoparticle layer on a piezoelectric material (quartz), working as a guiding layer by confining SH-SAW energy and obtaining a Love-wave sensor. The perturbation produced in the elastic properties of the nanoparticle layer due to its interaction with gases induced a change in wave velocity that was detected by the frequency shift of an oscillator, working as a sensitive layer. Therefore, the Love-wave sensor was optimized with multi-guiding layers containing an intermediate guiding layer of SiO2. The Love-wave multi-guiding layer sensor was tested to different concentrations of toluene and benzene, measurements showed high sensitivity, short response time, and good reproducibility, and ability to detect very low concentrations of test gases, such 1 ppm of toluene and 25 ppm of benzene.

Chemoresistive gas microsensors with highly hydrogen sensitive zinc oxide rods dominated by exposed {100} surfaces are fabricated. The hexagonal rod structures are integrated into micromachined transducing platforms without the need for substrate pre-treatment, via a vapor-solid mechanism enabled using an aerosol-assisted chemical vapor deposition method. The microsensors demonstrate an enhanced functionality towards hydrogen, with greater sensor responses (between 200% and 1800%) compared to other gases including ethanol, carbon monoxide, acetone, and toluene, and with low interferences among these reductive gases. The improved functionality of these systems towards hydrogen is attributed to the formation of an accumulation layer at the zinc oxide rods after hydrogen exposure, which includes a mechanism not only dominated by the oxygen vacancies, but also by the formation of intermediate energy levels for the transfer of charge from hydrogen to the zinc oxide conduction band.

A portable electronic nose based on surface acoustic wave (SAW) sensors is proposed in this work to detect toxic chemicals, which have a great potential to threaten the surrounding natural environment or adversely affect the health of people. We want to emphasize that ferrite nanoparticles, decorated (Au, Pt, Pd) and undecorated, have been used as sensitive coatings for the first time in these types of sensors. Furthermore, the proposed electronic nose incorporates signal conditioning and acquisition and transmission modules. The electronic nose was tested to low concentrations of benzene, toluene, and xylene, exhibiting excellent performance in terms of sensitivity, selectivity, and response time, indicating its potential as a monitoring system that can contribute to the detection of toxic compounds., This work was supported by the Fundación General CSIC via Programa ComFuturo and the Spanish Ministry of Science, Innovation and Universities under the projects RTI2018-095856-B-C22 (AEI/FEDER) and TEC2016-79898-C6 (AEI/FEDER).

A new method for the site-selective synthesis of nanowires has been developed to enable material growth with defined morphology and, at the same time, different composition on the same chip surface. The chemical vapor deposition approach for the growth of these nanowire-based resistive devices using micromembranes can be easily modified and represents a simple, adjustable fabrication process for the direct integration of nanowire meshes in multifunctional devices. This proof-of-concept study includes the deposition of SnO2, WO3, and Ge nanowires on the same chip. The individual resistors exhibit adequate gas sensing responses toward changing gas concentrations of CO, NO2, and humidity diluted in synthetic air. The data have been processed by principal component analysis with cluster responses that can be easily separated, and thus, the devices described herein are in principle suitable for environmental monitoring.

BACKGROUND This study describes our experience with laryngeal mask (LM) inserted after anesthetic induction in patients already in knee-chest position for lumbar neurosurgery. METHODS Airway management (need for LM repositioning, orotracheal intubation because of failed LM insertion), anticipated difficult airway, and airway complications were registered. Statistics were compared between groups with the t test or the χ test, as appropriate. RESULTS A total of 358 cases were reviewed from 2008 to 2013. Tracheal intubation was performed in 108 patients and LM was chosen for 250 patients (69.8%). Intubated patients had a higher mean age and rate of anticipated difficult airway; duration of surgery was longer (P

Gas-sensitive structures with nanoscale heterojunctions are formed by the co-deposition of WO3-x nanoneedles and Fe2O3 nanoparticles via aerosol-assisted chemical vapour deposition. These composite structures demonstrate enhanced gas sensor performance to ethanol, methanol, acetone, and toluene compared to bare WO3-x nanoneedles devoid of heterojunctions, with better selectivity for the group of analytes studied.

The gas sensing properties of germanium (Ge) monocrystalline nanowires (NWs) at temperatures up to 100 °C have been demonstrated for the first time. The devices have been fabricated based on an energy efficient and site-specific vapor-liquid-solid growth of NW meshes on top of microhotplates, which contain a buried heater and top electrodes. The devices have been investigated for the detection of oxygen, nitrogen dioxide and carbon monoxide gases, showing the important effect played by pre-adsorbed surface oxygen in the response to the different gases. The Ge NW-based devices exhibit p-type conductivity and show high selectivity in their response towards water vapor. Water vapor interaction is not dependent on the presence of oxygen and the adsorption leads to electron donation in the Ge nanowires. TEM analysis of the NWs proves that they are covered by a thin, outer germanium oxide layer, which is stable and does not grow upon exposure to these gases and operation temperatures up to 100 °C. The presence of this oxide layer plays a key role in the sensing mechanisms.

Indium oxide nanostructures have been prepared by carbothermal reduction method. From them, nanowires have been structurally and optically characterized using X-ray diffraction, scanning and transmission electron microscopy and photoluminescence. The indium oxide nanowires have been removed from the substrate and contacted by Focused Electron- and Focused Ion-Beam Induced Deposition techniques to interdigitates on suspended microhotplates, which allow heating up to 300 °C with a low power consumption of only 8 mW. The gas response of the tested devices towards ethanol, carbon monoxide and nitrogen dioxide diluted in dry synthetic air at different concentrations and temperatures has been carried out showing a selectivity towards ethanol with responses up to 50% at temperatures between 200 and 300 °C, while only small response to high concentrations of carbon monoxide and nitrogen dioxide is observed.

In this contribution we present a highly miniaturized device that integrates a photoactive material with a highly efficient LED light source. This so-called micro light plate configuration (µLP) allows for maximizing the irradiance impinging on the photoactive material, with a minimum power consumption, excellent uniformity and accurate control of the illumination. We demonstrate that, with the µLP approach, very efficient low power gas sensors can be built, and provide a detailed analysis of the rationales behind such improvement, as well as a quantitative model and a set of design rules to implement it in further integrated applications. As a demonstrator, we will describe a NO2 gas sensor operating in the part per billion range (ppb) with microwatt (µW) power consumption. These are the best figures reported to date in conductometric metal-oxides (MOX) sensors operated with light (instead of heat) at room temperature.

Based on the recently reported "micro-light-plate" configuration, we have implemented a light activated gas sensor for NO 2 operating at room temperature. With this conductometric device, we achieved detection limits down to a few parts per billion (ppb) with power consumption in the tens of microwatt range (µW). These are record values for conductometric metal-oxides (MOX) sensors activated with light (instead of heat).

We present a NO 2 gas sensor operating in the part per billion range (ppb) with microwatt (μW) power consumption. These are the best figures reported to date in conductometric metal-oxides (MOX) sensors operated with light (instead of heat) at room temperature. We achieved these remarkable figures miniaturizing the devices in a novel monolithic-integrated configuration, so-called “micro-light-plate”.

A film of gas sensitive ZnO nanoparticles has been coupled with a low-power micro light plate (μLP) to achieve a NO

A film of gas sensitive ZnO nanoparticles has been coupled with a low-power micro light plate (μLP) to achieve a NO2-parts-per-billion conductometric gas sensor operating at room temperature. In this μLP configuration, an InGaN-based LED (emitting at 455 nm) is integrated at a few hundred nanometers distance from the sensor material, leading to sensor photoactivation with well controlled, uniform, and high irradiance conditions, and very low electrical power needs. The response curves to different NO2 concentrations as a function of the irradiance displayed a bell-like shape. Responses of 20% to 25 ppb of NO2 were already observed at irradiances of 5 mWatts·cm-2 (applying an electrical power as low as 30 μW). In the optimum illumination conditions (around 60 mWatts·cm-2, or 200 μW of electric power), responses of 94% to 25 ppb were achieved, corresponding to a lower detection limit of 1 ppb of NO2. Higher irradiance values worsened the sensor response in the parts-per-billion range of NO2 concentrations. The responses to other gases such as NH3, CO, and CH4 were much smaller, showing a certain selectivity toward NO2. The effects of humidity on the sensor response are also discussed.

We report a miniaturized device integrating a photoactive material with a highly efficient Light Emitting Diode light source. This so-called micro light plate configuration allows for maximizing the irradiance impinging on the photoactive material, with a minimum power consumption, excellent uniformity, and accurate control of the illumination. We demonstrate these advantages with an example application: photoactivated gas sensors with a power consumption as low as 30 μW (this is 1000 times lower than the best figures reported to date). The letter also presents a quantitative model and a set of design rules to implement it in further integrated applications.

A new method for the site-selective synthesis of nanowires has been developed to enable the material growth with specific morphology and different compositions on one single chip. Based on a modification of the chemical vapor deposition method, the growth of nanowires on top of micromembranes can be easily tuned and represents a simple and adjustable fabrication process for the direct integration of different nanowire-based resistive multifunctional devices. This proof-of-concept is exemplified by the deposition of SnO2, WO3 and Ge nanowires on the membranes of one single chip and their gas sensing responses towards different concentrations of CO, NO2 and humidity diluted in synthetic air are evaluated. The principal component analysis of the collected data allows gas identification and, thus, the system is suitable for environmental monitoring.

In the present work, a novel, portable and innovative eNose composed of a surface acoustic wave (SAW) sensor array based on zeolitic imidazolate frameworks, ZIF-8 and ZIF-67 nanocrystals (pure and combined with gold nanoparticles), as sensitive layers has been tested as a non-invasive system to detect different disease markers, such as acetone, ethanol and ammonia, related to the diagnosis and control of diabetes mellitus through exhaled breath. The sensors have been prepared by spin coating, achieving continuous sensitive layers at the surface of the SAW device. Low concentrations (5 ppm, 10 ppm and 25 ppm) of the marker analytes were measured, obtaining high sensitivities, good reproducibility, short time response and fast signal recovery., This work has been supported by Universidad Nacional Autónoma de México via Grants DGAPA-UNAM-PAPIIT TA100118 and DGAPA-UNAM-PAPIIT IT100518, the Fundación General CSIC via Programa ComFuturo, and the Spanish Ministry of Science and Innovation via Grant TEC2016-79898-C6-(AEI/FEDER,EU). This research has used the Spanish ICTS Network MICRONANOFABS (partially funded by MINECO), We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Chemoresitive gas sensors based on multiple nanowires (M-NWs) randomly grown and electrically inter-connected on the top of interdigitated electrodes (IDEs) and arrays of single nanowires connected between faced nanoelectrodes (A-S-NWs) are developed in this work. These systems, consisting of gas sensitive tungsten oxide nanowires (NWs), are tested to NO2, and their performance regarding the response magnitude, sensitivity and response rate are evaluated here.

The sensing properties of (3-aminopropyl)triethoxysilane modified tungsten oxide nanowires (APTES@WO3-x) based sensors towards several gases and vapors are reported in this work. The developed sensors show high sensitivity to ethanol and nitrogen dioxide under UV-irradiation at room temperature (24 °C). Gas sensing results demonstrate enhanced sensing properties for the APTES@WO3-x compared to non-modified WO3-x sensors, with the APTES@WO3-x sensors showing approximately 17 and 20 times more sensitivity to ethanol and nitrogen dioxide, respectively, compared to the non-modified WO3-x sensors. The APTES@WO3-x sensors also display improved selectivity to nitrogen dioxide (oxidizing gas) and ethanol (among other reducing gases including acetone, toluene, hydrogen, and carbon monoxide). These results are attributed to the presence of the reactive amino group at the APTES@WO3-x sensors, which facilitates the chemical interaction with nitrogen dioxide and ethanol and the electron transfer towards/from WO3-x under UV-light excitation.