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Highlights: Recent progress in noble metal-decorated (NM-D) semiconducting metal oxides (SMOs) gas sensors are summarized. Gas sensing mechanisms related to noble metal decoration are carefully discussed. Crucial challenges facing the development of NM-D SMOs gas sensors are analyzed. Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring, exhaled breath diagnosis, and food freshness analysis. Among various chemiresistive sensing materials, noble metal-decorated semiconducting metal oxides (SMOs) have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals. This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures (e.g., nanoparticles, nanowires, nanorods, nanosheets, nanoflowers, and microspheres) for high-performance gas sensors with higher response, faster response/recovery speed, lower operating temperature, and ultra-low detection limits. The key topics include Pt, Pd, Au, other noble metals (e.g., Ag, Ru, and Rh.), and bimetals-decorated SMOs containing ZnO, SnO2, WO3, other SMOs (e.g., In2O3, Fe2O3, and CuO), and heterostructured SMOs. In addition to conventional devices, the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed. Moreover, the relevant mechanisms for the sensing performance improvement caused by noble metal decoration, including the electronic sensitization effect and the chemical sensitization effect, have also been summarized in detail. Finally, major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] Highly sensitive and stable acetone gas sensors based on MEMS substrate supported carbon nanoparticles decorated mesoporous α-Fe 2 O 3 (C- d -mFe 2 O 3) nanorods (NRs) derived from Fe-MIL-88B-NH 2 NRs were first synthesized via a sequential process including a facile hydrothermal reaction and one-step pyrolysis at a moderate temperature in air. The MEMS architecture ensures low power consumption, small size, and high integration of the sensor. The obtained C- d -mFe 2 O 3 NRs exhibit good thermal stability and superior acetone sensing performance with excellent response (R a /R g = 5.2 to 2.5 ppm) and selectivity, fast response/recovery speed (10/27 s), and low detection limit of 500 ppb at 225 °C. Furthermore, the acetone sensor exhibits remarkable long-term stability and repeatability even after being stored in air for over 10 months. The enhanced acetone sensing performance could be attributed to the large specific surface area of mesoporous α-Fe 2 O 3 NRs, highly conductive carbon nanoparticles on the surface, and the formation of α-Fe 2 O 3 /C heterojunction. Density functional theory (DFT) calculations help to further confirm the superior acetone sensing performance. The competitive performance makes C- d -mFe 2 O 3 NRs gas sensor a great potential for practical application in environmental harmful acetone gas monitoring. [ABSTRACT FROM AUTHOR]

Development of high-performance ammonia (NH 3) sensor is imperative for monitoring NH 3 in the living environment. In this work, to obtain a high performance NH 3 gas sensor, structurally well-defined WO 3 @SnO 2 core shell nanosheets with a controllable thickness of SnO 2 shell layer have been employed as sensing materials. The prepared core shell nanosheets were used to obtain a miniaturized gas sensor based on micro-electro-mechanical system (MEMS). By tuning the thickness of SnO 2 layer via atomic layer deposition, a series of WO 3 @SnO 2 core-shell nanosheets with tunable sensing properties were realized. Particularly, the sensor base on the fabricated WO 3 @SnO 2 nanosheets with 20-nm SnO 2 shell layer demonstrated superior gas sensing performance with the highest response (1.55) and selectivity toward 15 ppm NH 3 at 200 °C. This remarkable enhancement of NH 3 sensing ability could be ascribed to the formation of unique WO 3 -SnO 2 core-shell heterojunction structure. The detailed mechanism was elucidated by the heterojunction-depletion model with the help of specific band alignment. [ABSTRACT FROM AUTHOR]

• Heterostructured p-CuO/n-SnO2 core-shell NWs with precisely controlled shell thickness were synthesized by ALD technique. • The p-CuO/n-SnO2 core-shell NW structured gas sensors with 24 nm SnO2 shell layer exhibited enhanced sensing performance. • The well-structured core-shell NWs also have excellent selectivity for HCHO. Highly sensitive and selective gas sensors based on heterostructured p -CuO/ n -SnO 2 core-shell nanowires (NWs) with precisely controlled shell thickness were synthesized through a sequential process combining a solution processing and atomic layer deposition. The gas sensing devices were fabricated on micro-electromechanical systems, which has triggered great research interest for low power consumption and highly integrated design. The designed p -CuO/ n -SnO 2 core-shell NW structured gas sensors exhibited superior gas sensing performance, which is closely related to the thickness of the SnO 2 shell. Specifically, p -CuO/ n -SnO 2 core-shell NWs with a 24 nm thick SnO 2 shell displayed a high sensitivity (R a /R g) of 2.42, whose rate of resistance change (i.e. 1.42) is 3 times higher than the pristine CuO NW sensor when detecting 50 ppm formaldehyde (HCHO) at 250 °C. The enhanced gas sensing performance could be attributed to the formation of p - n heterojunction which was revealed by specific band alignment and the heterojunction-depletion model. Besides, the well-structured p -CuO/ n -SnO 2 core-shell NWs achieved excellent selectivity for HCHO from commonly occurred reducing gases. In a word, such heterostructured p -CuO/ n -SnO 2 core-shell NW gas sensors demonstrate a feasible approach for enhanced sensitive and selective HCHO detection. [ABSTRACT FROM AUTHOR]

Objective To investigate the causal relationship between serum vitamin levels and risk of insomnia using two-sample Mendelian randomization. Methods Single nucleotide polymorphisms associated with four serum vitamins, including serum 25 (OH) D, vitamin B12, vitamin C, vitamin E, were obtained from published genome-wide association studies. Summary-level data for the genetic associations with insomnia were obtained from UK Biobank. Then, the inverse variance-weighted (IVW) was used to conduct Mendelian randomization analysis. At the same time, MR-PRESSO and MR-Egger were used to detect the level multipotency, and "leave-one -out" sensitivity was analyzed. Results In studies on the effect of serum vitamin levels on insomnia, IVW method showed that serum 25 (OH) D was causally associated with a lower risk of insomnia. Furthermore, the IVW method demonstrated no causal relationship between serum vitamin B12, vitamin C, vitamin E levels and insomnia risk. Reverse-direction MR analysis suggested non-causal relationship of insomnia on the levels of serum 25(OH)D, vitamin B12, vitamin C, vitamin E. Conclusion The results elucidate a causal link between genetically determined higher serum 25 (OH) D levels and lower risk of insomnia. [ABSTRACT FROM AUTHOR]

Heterostructured α-Fe 2 O 3 /SnO 2 core-shell nanowires (NWs) are successfully synthesized assisted with atomic layer deposition (ALD). The gas sensing properties of α-Fe 2 O 3 /SnO 2 core-shell NWs with various shell thicknesses in the range of 5–28 nm are investigated. The gas sensing mechanism is fully analyzed based on both the widely accepted electron depletion model and the Debye length concept. When the shell thickness reaches ∼18 nm, the sensor of the heterostructured α-Fe 2 O 3 /SnO 2 core-shell NWs exhibit high responses (R a /R g) of 4.3 towards 10 ppm and 1.5 towards 1 ppm H 2 S at 250 °C, excellent selectivity, remarkable repeatability, and long-term stability of at least 3 months, which completely exceed that of pristine α-Fe 2 O 3 NWs. The formation of α-Fe 2 O 3 /SnO 2 heterojunction contributes to the effectively enhanced performance, which is further investigated and confirmed by density functional theory calculations. In addition, the sensors are fabricated based on specially designed MEMS sensing devices, providing excellent heating conditions for sensitive nanomaterials with the merits of low power consumption and high integration. • Heterostructured α-Fe 2 O 3 /SnO 2 core-shell NWs with precisely controlled shell thickness were prepared by ALD. • The SnO 2 shell thickness had a critical effect on the gas sensing properties of the α-Fe 2 O 3 /SnO 2 NWs sensors. • The well-designed MEMS-based sensor exhibited superior H 2 S sensing with low power consumption. [ABSTRACT FROM AUTHOR]

Hierarchical Nb 2 O 5 @ZnO hetero-branched nanorods used for highly responsive, selective, and stable hydrogen sulfide (H 2 S) sensors were synthesized through a sequential process combining a hydrothermal method, atomic-layer-deposition processing, and modified hydrothermal processing for branching ZnO nanowires. The Nb 2 O 5 @ZnO hetero-branched nanorod sensors exhibited a great response (R a /R g) of 6.10 towards 20 ppm H 2 S at an optimal working temperature of 400 °C, whose resistance changing rate (∼5.10) was 39.2- and 1.9-fold those of Nb 2 O 5 (∼0.13) and Nb 2 O 5 @ZnO core-shell nanorod (∼2.74) sensors, respectively. The heterojunction formed at the Nb 2 O 5 @ZnO interface and the characteristic reaction between ZnO and H 2 S effectively improved H 2 S sensing performance. Moreover, the branching of ZnO nanowires introduced abundant homojunctions and prominently enlarged the specific surface area, further increasing the response of hetero-branched sensors. Meanwhile, the Nb 2 O 5 @ZnO hetero-branched sensors maintained steady performance over a month, indicating good stability and repeatability. In a word, such hierarchical Nb 2 O 5 @ZnO hetero-branched nanorod gas sensors are promising for the development of sensitive and selective H 2 S detection. • Hierarchical Nb 2 O 5 @ZnO hetero-branched NRs were precisely prepared assisted by ALD. • The hetero-branched Nb 2 O 5 @ZnO NR sensor exhibits improved H 2 S sensing properties compared to that of core-shell NRs. • The sensors were fabricated on MEMS with low power consumption, long-term stability, and excellent sensitivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • ALD of controllable SnO 2 shell thickness on Nb 2 O 5 nanorods for H 2 S sensing. • The H 2 S sensing performance is closely related to the thickness of SnO 2 shell. • The H 2 S sensors exhibit high response, good selectivity, and excellent stability. Heterostructured Nb 2 O 5 /SnO 2 core-shell nanorods are synthesized by a facile hydrothermal strategy and atomic layer deposition (ALD). The SnO 2 shell thicknesses varying from 7 to 34 nm exhibit a significant impact on sensing performance. The response enhancement mechanism of the Nb 2 O 5 /SnO 2 core-shell nanorods is illustrated based on the electron-depletion model. The Nb 2 O 5 /SnO 2 core-shell nanorods gas sensors were synthesized based on the micro-electromechanical systems (MEMS), which could provide variable operating temperatures for the gas sensors with highly integrated design and low power consumption. The response of the Nb 2 O 5 /SnO 2 core-shell nanorods gas sensor deposited with 20 nm SnO 2 shell towards 20 ppm H 2 S at 275 °C was 4.0, which showed a 3.8-fold of improvement compared with pristine Nb 2 O 5 nanorods. Furthermore, the well-structured core-shell nanorods gas sensors maintained stable performance after three months, presenting long-term stability and repeatability. The proposed Nb 2 O 5 /SnO 2 core-shell nanorods gas sensors demonstrate a potential strategy for the practical application in oil and gas drilling platforms and other industrial fields. [ABSTRACT FROM AUTHOR]

The development of high-performance H 2 S sensor is imperative for monitoring H 2 S in the living environment. Metal oxide semiconductors (MOSs) have been regarded as the strongest candidates for H 2 S detection due to their high sensitivity, miniaturization, and good durability. However, a single MOS-based gas sensor is unable to selectively detect gases, which limits its practical application. Functionalization of noble metal nanoparticles (e.g., Pt, Pd, and Au) on the surface of MOS can improve its selectivity. Herein, ZnO nanowires decorated with AuPt bimetallic nanoparticles are designed and fabricated on MEMS for H 2 S detection. The AuPt@ZnO nanowires-based sensor shows a response of 17.7–20 ppm H 2 S at 300 °C which is 4.0 times higher than that of pristine ZnO nanowires-based sensor. The sensor also exhibits a rapid response-recovery process, brilliant long-term stability, and excellent selectivity to H 2 S among various interfering gases. The remarkable improvement of the sensing performance, especially selectivity, could be ascribed to the electronic and chemical sensitization and the synergistic effect of the AuPt bimetal. Thus, the AuPt@ZnO nanowires-based sensor has a great potential application for H 2 S detection. • The AuPt@ZnO nanowires were synthesized by a hydrothermal method and reduction treatment. • The AuPt@ZnO-based sensor towards H 2 S was prepared via simply dropping the AuPt@ZnO nanowires solution on the MEMS. • The AuPt@ZnO-based sensor exhibited high response, excellent selectivity and short response time towards H 2 S. • The electronic and chemical sensitization and the synergistic effect of the AuPt bimetal could improve sensing properties. [ABSTRACT FROM AUTHOR]

Dilution enthalpies of urea (U) and its four derivatives {biuret (BU), methylurea (MU), 1,1-dimethylurea (1,1-DMU) and 1,3-dimethylurea (1,3-DMU)} in (dimethylformamide (DMF) + water) mixtures of various mole fractions ( x DMF = 0 to 0.10) at T = 298.15 K have been determined by isothermal titration calorimetry (ITC). In light of the approach of McMillan–Mayer’s theory, enthalpic pairwise self-interaction coefficients ( h 2 ) of each compound at the corresponding composition ( x DMF ) of mixed solvent (DMF + water) have been calculated. It is found that the h 2 coefficients of each compound are all negative in pure water and increase incrementally with the concentration of DMF in the mixed solvent, following the order h 2 (BU) < h 2 (U) < h 2 (MU) < h 2 (1,1-DMU) < h 2 (1,3-DMU). It is concluded that (1) the addition of co-solvent DMF to solvent water is unfavourable to the pairwise self-interactions of these solutes from the point of view of enthalpy; (2) the substitution of methyl (Me) on N atom of urea enhances the component of hydrophobic interactions during the pairwise self-interactions of these solutes; (3) BU is a more hydrophilic molecule than U, and 1,3-DMU is a more hydrophobic molecule than 1,1-DMU. [ABSTRACT FROM AUTHOR]

The dilution enthalpies of four derivatives of monosaccharides, namely 2-deoxy- d -glucose (2-DGlu), N-acetyl- d -glucosamine (GluNAc), 2-deoxy- d -galactose (2-DGal) and N-acetyl- d -galactosamine (GalNAc), in aqueous NaCl solutions of various molalities ( b = 0–3.0 mol · kg −1 ) have been determined respectively at T = 298.15 K by isothermal titration calorimetry (MicroCal ITC200). The corresponding values of enthalpic pairwise self-interaction coefficients ( h 2 ) have been calculated according to the McMillan–Mayer theory. It was found that across the range studied of ionic strength ( I ) or molality ( b = I ), the h 2 coefficients are all positive, in the order h 2 (GluNAc) > h 2 (GalNAc) > h 2 (2-DGlu) > h 2 (2-DGal), and decrease gradually after increasing first up to a maximum at b ≈ 1.5 mol · kg −1 . The effects of ionic strength ( I ) on the trends of h 2 have been discussed from the point of view of complex (solute + solute) and (solute + solvent) interactions in solutions. [ABSTRACT FROM AUTHOR]

Highlights: Latest progress on flexible room temperature (FRT) gas sensor based on metal oxide semiconductors (MOS) is comprehensively reviewed. FRT gas sensor based on pristine MOS and MOS modified with noble metal nanoparticles, organic polymers, carbon based materials and transition metal dichalcogenide materials are meticulously reviewed. The gas sensing mechanism of MOS chemiresistive gas sensors are introduced and the applications, future perspectives, and challenges of FRT gas sensors are also proposed. With the rapid development of the Internet of Things, there is a great demand for portable gas sensors. Metal oxide semiconductors (MOS) are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors. However, it is limited by high operating temperature. The current research works are directed towards fabricating high-performance flexible room-temperature (FRT) gas sensors, which are effective in simplifying the structure of MOS-based sensors, reducing power consumption, and expanding the application of portable devices. This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism, performance, flexibility characteristics, and applications. This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors, including pristine MOS, noble metal nanoparticles modified MOS, organic polymers modified MOS, carbon-based materials (carbon nanotubes and graphene derivatives) modified MOS, and two-dimensional transition metal dichalcogenides materials modified MOS. The effect of light-illuminated to improve gas sensing performance is further discussed. Furthermore, the applications and future perspectives of FRT gas sensors are also discussed. [ABSTRACT FROM AUTHOR]

• ZnO branched p-Cu x O @n-ZnO heterojunction nanowires was fabricated by hydrothermal method and atomic layer deposition. • The designed ZnO branched NWs structured MEMS gas sensors have better gas sensing performance and selectivity to acetone. • The response of ZnO branched NWs sensors to 50 ppm acetone at an optimized operating temperature of 250 °C is approximately 6.4. A simple and effective preparation method was proposed to improve acetone gas sensing performance based on ZnO branched p-Cu x O@n-ZnO nanowires (NWs) by hydrothermal processing and atomic layer deposition technique. The gas sensor was fabricated on micro-electromechanical systems with lower power consumption and better integrated circuit compatibility. Compared with bare Cu x O NWs and p-Cu x O@n-ZnO core-shell NWs, the designed ZnO branched p-Cu x O@n-ZnO NWs have higher gas response and better selectivity to acetone. The response value of the branched p-Cu x O@n-ZnO NWs based sensor to 50 ppm acetone at the optimal temperature of 250 °C is approximately 6.4, which is 5 and 3.5 times of the devices with pristine Cu x O and p-Cu x O@n-ZnO core-shell NWs, respectively. The sensitivity enhancement mechanism of branched NWs is explained based on the depletion principle and the increased specific surface area. It is expected that the proposed ZnO branched p-Cu x O@n-ZnO NWs has a good reference for the development of high sensitivity and selectivity gas sensors. [ABSTRACT FROM AUTHOR]

Stretchable strain sensor, an important paradigm of wearable sensor which can be attached onto clothing or even human skin, is widely used in healthcare, human motion monitoring and human-machine interaction. Pattern-available and facile manufacturing process for strain sensor is pursued all the time. A carbon nanotube (CNT)/silver nanowire (AgNW)-based stretchable strain sensor fabricated by a facile process is reported here. The strain sensor exhibits a considerable Gauge factor of 6.7, long-term durability (>1000 stretching cycles), fast response and recovery (420 ms and 600 ms, respectively), hence the sensor can fulfill the measurement of finger movement. Accordingly, a smart glove comprising a sensor array and a flexible printed circuit board is assembled to detect the bending movement of five fingers simultaneously. Moreover, the glove is wireless and basically fully flexible, it can detect the finger bending of wearer and display the responses distinctly on an APP of a smart phone or a host computer. Our strain senor and smart glove will broaden the materials and applications of wearable sensors. [ABSTRACT FROM AUTHOR]

Knowledge of the influence of ions of various nature on intermolecular hydrophilic and hydrophobic interactions in solutions is required in many research fields. In this paper, dilution enthalpies of zwitterion l -carnitine in aqueous NaCl, KCl and NaBr solutions of various molalities ( b = 0 to 3.0 mol · kg −1 ) have been determined respectively at T = (298.15 ± 0.01) K and p = (0.100 ± 0.005) MPa by isothermal titration calorimetry (ITC). In light of the MacMillan–Mayer theory, the 2nd virial enthalpic coefficients ( h 2 ) have been calculated. The h 2 coefficients increase gradually with increasing molality ( b ) of the three aqueous alkali halides solutions, from small negative values in pure water to relatively larger positive values in solution. The trends of h 2 coefficients are ascribed to the salt effects on the balance between hydrophilic and hydrophobic interactions in pairwise self-associations. It is considered that the size of cations and anions exert influences on h 2 coefficients through their surface charge densities and hydration (or dehydration) abilities. [ABSTRACT FROM AUTHOR]

Zinc tin oxide (ZTO) thin films can be deposited by atomic layer deposition (ALD) with adjustable electrical, optical and structural properties. However, the ternary ALD processes usually suffer from low growth rate and difficulty in controlling film thickness and elemental composition, due to the interaction of ZnO and SnO 2 processes. In this work, ZTO thin films with different Sn levels are prepared by ALD super cycles using diethylzinc, tetrakis(dimethylamido)tin, and water. It is observed that both the film growth rate and atom composition show nonlinear variation versus [Sn]/([Sn]+[Zn]) cycle ratio. The experimental thickness measured by spectroscopic ellipsometry and X-ray reflectivity are much lower than the expected thickness linearly interpolated from pure ZnO and SnO x films. The [Sn]/([Sn]+[Zn]) atom ratios estimated by X-ray photoelectron spectroscopy have higher values than that expected from the cycle ratios. Hence, to characterize the film growth behavior versus cycle ratio, a numerical method is proposed by simulating the effect of reduced density and reactivity of surface hydroxyls and surface etching reactions. The structure, electrical and optical properties of ZTO with different Sn levels are also examined by X-ray diffraction, atomic force microscope, Hall measurements and ultraviolet–visible–infrared transmittance spectroscopy. The ZTO turns out to be transparent nanocrystalline or amorphous films with smooth surface. With more Sn contents, the film resistivity gets higher (>1 Ω cm) and the optical bandgap rises from 3.47 to 3.83 eV. [ABSTRACT FROM AUTHOR]

Evidence about whether remnant cholesterol (RC), especially non-fasting RC, is a causal risk factor for coronary heart disease (CHD) in Chinese subjects is rare. Recently, estimated RC level (RCe) was applied in many studies with large population. We aimed to compare fasting and non-fasting RCe calculated by LDL-C level determined by different methods in Chinese subjects, and investigate their contributions to CHD. Levels of TC, TG and HDL-C were measured directly in 273 CHD patients (CHD group) and 136 controls (CON group) before and at 4 h after a daily breakfast. LDL-C level was measured directly or calculated by Friedewald equation at TG < 4.5 mmol/L. RC level estimated by calculated or measured LDL-C was termed as RCe1 or RCe2. Contributions of different RC levels to CHD were evaluated by multivariable logistic regression analysis. Both RCe1 and RCe2 increased significantly at 4 h after breakfast (both p < 0.05). RCe1 was significantly higher than RCe2 in fasting or non-fasting state (p < 0.05). RCe1 was closely related to RCe2, especially in the highest quartile of RCe1 (p < 0.05). Non-fasting RCe1 or RCe2 and fasting RCe2 independently predicted CHD after adjustment for traditional risk factors (all p < 0.05). Although RCe1 was significantly higher than RCe2, non-fasting RCe, no matter RCe1 or RCe2, after a daily breakfast was an independent predictor for CHD risk in Chinese subjects, indicating that the non-fasting state is critical in the development of atherosclerosis. [ABSTRACT FROM AUTHOR]

• Heterostructured α-Fe 2 O 3 /ZnO core-shell NWs with precisely controlled shell thickness were synthesized by ALD. • The NWs structured MEMS gas sensors with 20 nm ZnO shell layer exhibited enhanced sensitive and selective H 2 S detection. • The maximum response of the α-Fe 2 O 3 /ZnO core-shell NWs gas sensor to 5 ppm H 2 S is 5.98 at an operating temperature of 250 °C. The α-Fe 2 O 3 /ZnO core-shell nanowires (NWs) on micro-electro-mechanical system structure were prepared for hydrogen sulfide (H 2 S) gas sensing. Core α-Fe 2 O 3 NWs were prepared by thermal oxidation and the ZnO shell layer was coated by atomic layer deposition, respectively. The diameter of the obtained α-Fe 2 O 3 /ZnO core-shell NWs increases uniformly with the increase of ZnO shell thickness. When the operating temperature is 250 °C, the maximum response of the α-Fe 2 O 3 /ZnO core-shell NWs gas sensor to 5 ppm H 2 S is 5.98, which is about five times of pure α-Fe 2 O 3 NWs gas sensor (∼1.1). Moreover, α-Fe 2 O 3 /ZnO core-shell NWs-based gas sensors showed good selectivity, response, and recovery properties to H 2 S. The improvement of gas response of core-shell NWs is due to the slender α-Fe 2 O 3 /ZnO core-shell NWs and the appropriate energy band structure between ZnO and α-Fe 2 O 3. Thus, the proposed α-Fe 2 O 3 /ZnO core-shell NWs will be one of ideal sensitive materials for H 2 S high-performance sensor. [ABSTRACT FROM AUTHOR]

Successive dilution enthalpies ( Δ H ( m N - 1 → m N ) ) of glycidol enantiomers (R-(+)-glycidol, S-(−)-glycidol) and the racemate (R/S-(±)-glycidol) in (dimethylformamide (DMF) + water) mixtures rich in water (mass fractions of DMF, w DMF = 0 to 0.25) have been determined respectively by isothermal titration calorimetry (ITC) at T = 298.15 K. The corresponding homotactic enthalpic pairwise interaction coefficients ( h XX ) of each compound have been evaluated from the framework of McMillan–Mayer theory. Across the studied composition range of (DMF + water) mixtures the h XX values of these compounds are all positive, and decrease gradually with the mass fraction of DMF by the order h RR > h RS ≈ h MM > h SS > 0 (M represents the racemate R/S-(±)-glycidol, and h RS is the estimated value for the heterochiral pair R–S). The positive values of h XX indicate that pairwise interactions of these compounds are endothermic and unfavourable from the point of view of enthalpy. The interaction of S–S pair is considered to be slightly stronger than M–M, R–S and R–R pairs since the former absorbs less heat than the latter in pairwise interactions. The addition of cosolvent (DMF) is in favour of pairwise interactions of these compounds in the mixtures rich in water. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dilution enthalpies of 2′-deoxynucleosides in (DMSO+water) mixtures were determined. [•] Enthalpic coefficients (h xx) were calculated based on McMillan–Mayer’ theory. [•] The values of h xx are large negative cross the studied range of mixed solvents. [•] Hydrophilic interactions are proved to be prevailing in the ternary solutions. [•] The trends of h xx depend on the (hydrophobic/hydrophilic) equilibrium of solutes. [Copyright &y& Elsevier]

Thedilution enthalpies of nicotinamide (NA) and isonicotinamide(INA) in (dimethyl sulfoxide (DMSO) + water) and (dimethylformamide(DMF) + water) mixed solvents (M1 and M2) at 298.15 K have been determined,respectively, using an isothermal titration calorimeter (MicroCalITC200). On the basis of the McMillan-Mayer theory, enthalpic pairwiseself-interaction coefficients (hxx) of NA and INA in both M1 and M2 aqueous mixed solvents (molefractions of cosolvents xcos= 0 to 0.10)have been calculated. It was found that the values of hxxare all large negative, with the relativemagnitudes hxx(NA) < hxx(INA) < 0 in both M1 andM2, and hxx(in M1) > hxx(in M2) for both NA andINA, and that all of them increase monotonously with the concentrationsof cosolvents (both DMF and DMSO). It implies that an intense exothermiceffect accompanies with the pairwise hydrophilic–hydrophilicself-interactions, in which the meso-isomer (NA) behaves as a strongermolecular associator than the para-isomer (INA). [ABSTRACT FROM AUTHOR]

[Display omitted] • Aptasensor based on aptamer/Au NPs/GS was designed and fabricated. • The study is the first time to apply aptamer/Au NPs/GS/GCE to the detection of homocysteine. • The proposed aptasensor displayed a relatively wide detection range (1–100 µM) and low limit of detection (1 µM). The increase of homocysteine (Hcy) is closely related with the development of many diseases. Nevertheless, the effective detection of Hcy remains challenging due to the lack of a simple, specific, and cost-efficient method. Herein, an electrochemical biosensor based on Hcy aptamer/Au nano-particles/graphene sponge (Aptamer/Au NPs/GS) was designed for the detection of homocysteine. The biosensor employed methylene blue (MB) as a redox indicator. Due to the change of aptamer conformation, the adsorbed MB was released from aptamer, resulting in the decrease of electrochemical response. In the range of 1–100 μM, the concentration of Hcy had a good linear relationship with the relative redox peak current (Δ I) of MB and the lowest detection limit was 1 μM. The experimental results demonstrated the aptasensor had good selectivity and reproducibility. In real serum sample, the aptasensor showed an acceptable recovery rate indicating its potential applications in the preliminary detection of various diseases associated with Hcy. [ABSTRACT FROM AUTHOR]

Atomic scale control of the thickness of thin film makes atomic layer deposition highly advantageous in the preparation of high quality super-lattices. However, precisely controlling the film chemical stoichiometry is very challenging. In this study, we deposited SiOx film with different stoichiometry by plasma enhanced atomic layer deposition. After reviewing various deposition parameters like temperature, precursor pulse time, and gas flow, the silicon dioxides of stoichiometric (SiO2) and non-stoichiometric (SiO1.8 and SiO1.6) were successfully fabricated. X-ray photo-electron spectroscopy was first employed to analyze the element content and chemical bonding energy of these films. Then the morphology, structure, composition, and optical characteristics of SiOx film were systematically studied through atomic force microscope, transmission electron microscopy, X-ray reflection, and spectroscopic ellipsometry. The experimental results indicate that both the mass density and refractive index of SiO1.8 and SiO1.6 are less than SiO2 film. The energy band-gap is approved by spectroscopic ellipsometry data and X-ray photo-electron spectroscopy O 1s analysis. The results demonstrate that the energy band-gap decreases as the oxygen concentration decreases in SiOx film. After we obtained the Si-rich silicon oxide film deposition, the SiO1.6/SiO2 super-lattices was fabricated and its photoluminescence (PL) property was characterized by PL spectra. The weak PL intensity gives us greater awareness that more research is needed in order to decrease the x of SiOx film to a larger extent through further optimizing plasma-enhanced atomic layer deposition processes, and hence improve the photoluminescence properties of SiOx/SiO2 super-lattices. [ABSTRACT FROM AUTHOR]