Association between office visit intervals and long-term cardiovascular risk in hypertensive patients.

Hypertension is a chronic disease that requires long-term follow-up in many patients, however, optimal visit intervals are not well-established. This study aimed to evaluate the incidences of major cardiovascular events (MACEs) according to visit intervals. We analyzed data from 9894 hypertensive patients in the Korean Hypertension Cohort, which enrolled and followed up 11,043 patients for over 10 years. Participants were classified into five groups based on their median visit intervals (MVIs) during the 4-year period and MACEs were compared among the groups. The patients were divided into clinically relevant MVIs of one (1013; 10%), two (1299; 13%), three (2732; 28%), four (2355; 24%), and six months (2515; 25%). The median follow-up period was 5 years (range: 1745 ± 293 days). The longer visit interval groups did not have an increased cumulative incidence of MACE (12.9%, 11.8%, 6.7%, 5.9%, and 4%, respectively). In the Cox proportional hazards model, those in the longer MVI group had a smaller hazard ratio (HR) for MACEs or all-cause death: 1.77 (95% confidence interval [CI], 1.45-2.17), 1.7 (95% CI: 1.41-2.05), 0.90 (95% CI: 0.74-1.09) and 0.64 (95% CI: 0.52-0.79), respectively (Reference MVI group of 75-104 days). In conclusion, a follow-up visits with a longer interval of 3-6 months was not associated with an increased risk of MACE or all-cause death in hypertensive patients. Therefore, once medication adjustment is stabilized, a longer interval of 3-6 months is reasonable, reducing medical expenses without increasing the risk of cardiovascular outcomes.

Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides.

Co3O4 sensors with a nanoscale TiO2 or SnO2 catalytic overlayer were prepared by screen-printing of Co3O4 yolk-shell spheres and subsequent e-beam evaporation of TiO2 and SnO2. The Co3O4 sensors with 5 nm thick TiO2 and SnO2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co3O4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

Co3O4-SnO2 Hollow Heteronanostructures: Facile Control of Gas Selectivity by Compositional Tuning of Sensing Materials via Galvanic Replacement.

Co3O4 hollow spheres prepared by ultrasonic spray pyrolysis were converted into Co3O4-SnO2 core-shell hollow spheres by galvanic replacement with subsequent calcination at 450 °C for 2 h for gas sensor applications. Gas selectivity of the obtained spheres can be controlled by varying the amount of SnO2 shells (14.6, 24.3, and 43.3 at. %) and sensor temperatures. Co3O4 sensors possess an ability to selectively detect ethanol at 275 °C. When the amount of SnO2 shells was increased to 14.6 and 24.3 at. %, highly selective detection of xylene and methylbenzenes (xylene + toluene) was achieved at 275 and 300 °C, respectively. Good selectivity of Co3O4 hollow spheres to ethanol can be explained by a catalytic activity of Co3O4; whereas high selectivity of Co3O4-SnO2 core-shell hollow spheres to methylbenzenes is attributed to a synergistic effect of catalytic SnO2 and Co3O4 and promotion of gas sensing reactions by a pore-size control of microreactors.

Enhanced ethanol sensing characteristics of In2O3-decorated NiO hollow nanostructures via modulation of hole accumulation layers.

In this work, we report a dramatic enhancement in ethanol sensing characteristics of NiO hollow nanostructures via decoration with In2O3 nanoclusters. The pure NiO and 1.64-4.41 atom % In-doped NiO and In2O3-decorated NiO hollow spheres were prepared by ultrasonic spray pyrolysis, and their gas sensing characteristics were investigated. The response (the ratio between the resistance in gas and air) of the In2O3-decorated NiO hollow spheres to 5 ppm ethanol (C2H5OH) was 9.76 at 350 °C, which represents a significant improvement over the In-doped NiO and pure NiO hollow spheres (3.37 and 2.18, respectively). Furthermore, the 90% recovery time was drastically reduced from 1880 to 23 s, and a selective detection of ethanol with negligible cross-response to other gases was achieved. The enhanced gas response and fast recovery kinetics were explained in relation to the thinning of the near-surface hole accumulation layer of p-type NiO underneath n-type In2O3, the change of charge carrier concentration, and the variation of oxygen adsorption.

Honeycomb-like periodic porous LaFeO3 thin film chemiresistors with enhanced gas-sensing performances.

The use of composite materials and polynary compounds is a promising strategy to promote conductometric sensor performances. The perovskite oxides provide various compositional combinations between different oxides for tuning gas-sensing reaction and endowing rich oxygen deficiencies for preferable gas adsorption. Herein, a sacrificial colloidal template approach is exploited to fabricate crystalline ternary LaFeO3 perovskite porous thin films, by transferring a La(3+)-Fe(3+) hybrid solution-dipped template onto a substrate and sequent heat treatment. The honeycomb-like LaFeO3 film consisted of monolayer periodic pore (size: ∼ 500 nm) array can be successfully in situ synthesized in a homogeneous layout with a single phase of perovskite. This periodic porous LaFeO3 film with p-type semiconductivity exhibits a high gas response, fast response (∼4 s), trace detection capacity (50 ppb), and favorable ethanol selectivity from similar acetone. It exhibits enhanced sensing performances compared to those of a binary n-type Fe2O3 film and a nontemplated dense LaFeO3 film. In addition, a five-axe spiderweb diagram is introduced to make a feasible evaluation of the optimal practical work condition, comprehensively regarding the response/recovery rate, gas response, selectivity and operating temperature. The enhanced ethanol sensing mechanism of honeycomb-like LaFeO3 periodic porous film is also addressed. This novel and facile route to fabricate well-ordered porous LaFeO3 thin film can also be applied to many fields to obtain special performances, such as solar cells, ion conductors, gas separation, piezoelectricity, and self-powered sensing device system.

Design of highly sensitive and selective Au@NiO yolk-shell nanoreactors for gas sensor applications.

Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H2S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH3, CO and H2). The maximum response was 108.92 for 5 ppm of H2S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H2S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H2S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response.

Selective detection of NO2 using Cr-doped CuO nanorods.

CuO nanosheets, Cr-doped CuO nanosheets, and Cr-doped CuO nanorods were prepared by heating a slurry containing Cu-hydroxide/Cr-hydroxide. Their responses to 100 ppm NO(2), C(2)H(5)OH, NH(3), trimethylamine, C(3)H(8), and CO were measured. For 2.2 at% Cr-doped CuO nanorods, the response (R(a)/R(g), R(a): resistance in air, R(g): resistance in gas) to 100 ppm NO(2) was 134.2 at 250 °C, which was significantly higher than that of pure CuO nano-sheets (R(a)/R(g) = 7.5) and 0.76 at% Cr-doped CuO nanosheets (R(a)/R(g) = 19.9). In addition, the sensitivity for NO(2) was also markedly enhanced by Cr doping. Highly sensitive and selective detection of NO(2) in 2.2 at% Cr-doped CuO nanorods is explained in relation to Cr-doping induced changes in donor density, morphology, and catalytic effects.