AuPd–MnOx/MOF–Graphene: An Efficient Catalyst for Hydrogen Production from Formic Acid at Room Temperature

The safe and efficient storage and release of hydrogen are widely recognized as the main challenges for the establishment of a fuel‐cell‐based hydrogen economy. Formic acid (FA) has great potential as a safe and convenient source of hydrogen for fuel cells. Despite tremendous efforts, the development of heterogeneous catalysts with high activity and relatively low cost remains a major challenge. The synthesis of AuPd–MnO_x nanocomposite immobilized on ZIF‐8–reduced‐graphene‐oxide (ZIF‐8–rGO) bi‐support by a wet‐chemical method is reported here. Interestingly, the resultant AuPd–MnO_x/ZIF‐8–rGO shows excellent catalytic activity for the generation of hydrogen from FA, and the initial turnover frequency (TOF) reaches a highest value of 382.1 mol H₂ mol catalyst^?1 h^?1 without any additive at 298 K. This good performance of AuPd–MnO_x/ZIF‐8–rGO results from the modified electronic structure of Pd in the AuPd–MnO_x/ZIF‐8–rGO composite, the small size and high dispersion of the AuPd–MnO_x nanocomposite, and also the strong metal‐support interaction between the AuPd–MnO_x and ZIF‐8–rGO bi‐support.     

A hybrid boronate affinity probe for the selective detection of cis-diol containing compounds in tea beverages

UiO-66-NH₂ nanocomposite was post-modified with 4-mercaptophenylboronic acid (MPBA) by the method of in situ hybridization reaction. The hybrid boronate affinity material UiO-NH₂@P (TEPIC-co-MPBA) was characterized by scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. The material was applied as fluorescent probe for the detection of cis-diol containing compounds based on the boronate affinity mechanism, and exhibited high specific selectively. The proposed method exhibited good linearity for the detection of catechol in the range of 0.50 to 8.00 μg ml⁻¹. The detection limit was 0.13 μg ml⁻¹. The tactic was successfully applied to analyze the total polyphenols in tea beverages for catechol, and relative recovery was in 98.86–106.00%. Therefore, this work provided a promising strategy for the recognition of cis-diol containing compounds.     

Citrate‐Assisted Growth of NiCo2O4 Nanosheets on Reduced Graphene Oxide for Highly Reversible Lithium Storage

Hybrid nanostructures based on graphene and transition metal oxides hold great promise as high‐performance electrode materials for next‐generation lithium‐ion batteries. In this work, the rational design and fabrication of NiCo₂O₄ nanosheets supported on reduced graphene oxide (denoted as rGO/NiCo₂O₄) is presented as a novel anode material for highly efficient and reversible lithium storage. A solution method is applied to grow Ni‐Co precursor nanosheets on rGO, in which the addition of trisodium citrate is found crucial to guide the formation of uniform Ni‐Co precursor nanosheets. Subsequent thermal treatment results in formation of crystalline NiCo₂O₄ nanosheets on rGO without damaging the morphology. The interconnected NiCo₂O₄ nanosheets form hierarchically porous films on both sides of rGO. Such a hybrid nanostructure would effectively promote the charge transport and withstand volume variation upon prolonged charge/discharge cycling. As a result, the rGO/NiCo₂O₄ nanocomposite demonstrates high reversible capacities of 954.3 and 656.5 mAh g^–1 over 50 cycles at current densities of 200 and 500 mA g^–1 respectively, and remarkable capacity retention at increased current densities.     

Flexible and Highly Scalable V2O5‐rGO Electrodes in an Organic Electrolyte for Supercapacitor Devices

Vanadium pentoxide–reduced graphene oxide (rGO) free‐standing electrodes are used as electrodes for supercapacitor applications, eliminating the need for current collectors or additives and reducing resistance (sheet resistance 29.1 Ω □^?1). The effective exfoliation of rGO allows improved electrolyte ions interaction, achieving high areal capacitance (511.7 mF cm^?2) coupled with high mass loadings. A fabricated asymmetric flexible device based on rGO/V₂O₅‐rGO (VGO) consists of approximately 20 mg of active mass and still delivers a low equivalent series resistance (ESR) of 3.36 Ω with excellent cycling stability. A prototype unit of the assembled device with organic electrolyte is shown to light up eight commercial light‐emitting diode bulbs.     

Insights into the binding interaction between copper ferrite nanoparticles and bovine serum albumin: An effect on protein conformation and activity

The binding affinity between bovine serum albumin (BSA) and copper ferrite (CuFe₂O₄) nanoparticles in terms of conformation, stability and activity of protein was studied using various spectroscopic methods. The quenching involved in BSA–CuFe₂O₄ NP interaction was static quenching as analysed by different techniques (steady‐state and time‐resolved fluorescence along with temperature‐dependent fluorescence measurements). Among all types of possible interactions, it was revealed that the major binding forces were van der Waals interaction and hydrogen bonding, which were explored from negative values of enthalpy change (?H = ?193.85 kJ mol^?1) and entropy change (?S = ?588.88 J mol^?1 K^?1). Additionally, synchronous, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy measurements confirmed the conformational changes in BSA upon the addition of CuFe₂O₄ NP. Furthermore, thermal denaturation observations were consistent with the circular dichroism results. The interaction of CuFe₂O₄ NP with BSA decreased the esterase activity in the BSA assay, revealing the affinity of copper ferrite towards the active site of BSA.     

Turn‐off–on chemiluminescence determination of cyanide

A flow injection chemiluminescence (FI–CL) method was developed for the determination of cyanide (CN⁻) based on the recovered CL signal by Cu²⁺ inhibiting a glutathione (GSH)‐capped CdTe quantum dot (QD) and hydrogen peroxide system. In an alkaline medium, strong CL signals were observed from the reaction of CdTe QDs and H₂O₂, and addition of Cu²⁺ could cause significant CL inhibition of the CdTe QDs–H₂O₂ system. In the presence of CN⁻, Cu²⁺ can be removed from the surface of CdTe QDs via the formation of particularly stable [Cu(CN)_n]^(n‐1)– species, and the CL signal of the CdTe QDs–H₂O₂ system was efficiently recovered. Thus, the CL signals of CdTe QDs–H₂O₂ system were turned off and turned on by the addition of Cu²⁺ and CN⁻, respectively. Further, the results showed that among the tested ions, only CN⁻ could recover the CL signal, which suggested that the CdTe QDs–H₂O₂–Cu²⁺ CL system had highly selectivity for CN⁻. Under optimum conditions, the CL intensity and the concentration of CN⁻ show a good linear relationship in the range 0.0–650.0 ng/mL (R² = 0.9996). The limit of detection for CN⁻ was 6.0 ng/mL (3σ). This method has been applied to detect CN⁻ in river water and industrial wastewater with satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.     

Fabrication of an organic–inorganic nanocomposite carrier for enzyme immobilization based on metal–organic coordination

An organic–inorganic nanocomposite which combined mesoporous silica SBA-15 and chitosan using a carboxyl functionalized ionic liquid as the bridging agent (SBA@CS) was successfully fabricated, and was used to immobilize porcine pancreas lipase (PPL) by physical adsorption, cross-linking and metal–organic coordination, respectively. The as-prepared carriers were characterized by scanning electron microscopy, Fourier transform infrared and energy-dispersive X-ray spectroscopy. Compared with immobilization onto the pure mesoporous silicon material SBA-15, all the batches of PPL immobilized onto organic–inorganic nanocomposites showed higher activity, improved stability and reusability as well as better resistance to pH and temperature changes. Among the immobilized PPLs, immobilization based on Co²⁺ coordination (SBA@CS-Co-PPL) produced the best enzymatic properties. The maximum immobilization efficiency and specific activity of 79.6% and 1975.8 U g⁻¹ were obtained with SBA@CS-Co, separately. More importantly, the activity of immobilized enzyme can still maintain 84.0% after 10 times of reuse. These results demonstrated that thus prepared organic–inorganic nanocomposite could be an ideal carrier for enzyme immobilization by metal–organic coordination.     

Metal–Organic Framework Templated Porous Carbon‐Metal Oxide/Reduced Graphene Oxide as Superior Support of Bimetallic Nanoparticles for Efficient Hydrogen Generation from Formic Acid

Ultrafine PdAg nanoparticles (NPs) are successfully immobilized on zirconia/porous carbon/reduced graphene oxide (ZrO₂/C/rGO) nanocomposite derived from metal organic framework/graphene oxide. Monodispersed PdAg NPs (diameter ≤2.5 nm) can be facilely anchored on the ZrO₂/C/rGO and the aggregation of metal NPs can be avoided utmostly. By virtue of the synergistic effect between metal NPs and support, the resulting PdAg@ZrO₂/C/rGO exhibits excellent activity (turnover frequency, 4500 h^?1 at 333 K) for the dehydrogenation of formic acid. As an effective strategy, it provides an opportunity to immobilize ultrafine metal NPs on metal oxide/porous carbon/reduced graphene oxide, which has tremendous application prospects in various catalytic fields.     

Regulating effects of climate,net primary productivity,and nitrogen on carbon sequestration rates in temperate wetlands,Northeast China

Temperate wetlands in the Northern Hemisphere have high long-term carbon sequestration rates, and play critical roles in mitigating regional and global atmospheric CO₂ increases at the century timescale. We measured soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) from 11 typical freshwater wetlands (Heilongjiang Province) and one saline wetland (Jilin Province) in Northeast China, and estimated carbon sequestration rates using ²¹⁰Pb and ¹³⁷Cs dating technology. Effects of climate, net primary productivity, and nutrient availability on carbon sequestration rates (R_carbon) were also evaluated. Chronological results showed that surface soil within the 0–40 cm depth formed during the past 70–205 years. Soil accretion rates ranged from 2.20 to 5.83 mm yr⁻¹, with an average of 3.84 ± 1.25 mm yr⁻¹ (mean ± SD). R_carbon ranged from 61.60 to 318.5 gC m⁻² yr⁻¹ and was significantly different among wetland types. Average R_carbon was 202.7 gC m⁻² yr⁻¹ in the freshwater wetlands and 61.6 gC m⁻² yr⁻¹ in the saline marsh. About 1.04 × 10⁸ tons of carbon was estimated to be captured by temperate wetland soils annually in Heilongjiang Province (in the scope of 45.381–51.085°N, 125.132–132.324°E). Correlation analysis showed little impact of net primary productivity (NPP) and soil nutrient contents on R_carbon, whereas climate, specifically the combined dynamics of temperature and precipitation, was the predominant factor affecting R_carbon. The negative relationship observed between R_carbon and annual mean temperature (T) indicates that warming in Northeast China could reduce R_carbon. Significant positive relationships were observed between annual precipitation (P), the hydrothermal coefficient (defined as P/AT, where AT was accumulative temperature ≥10 °C), and R_carbon, indicating that a cold, humid climate would enhance R_carbon. Current climate change in Northeast China, characterized by warming and drought, may form positive feedbacks with R_carbon in temperate wetlands and accelerate carbon loss from wetland soils.     

Synthesis,characterization, and evaluation of (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate as a biological agent and an anion sensor

An amino acid based and bidentate Schiff base, (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate (ligand), was synthesized from the reaction of glycine-methyl ester hydrochloride with 2-hydroxy-1-naphthaldehyde. Characterization of the ligand was carried out using theoretical quantum–mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV–Visible spectroscopy, which were in good agreement with the structure predicted by the theoretical calculations using density functional theory (DFT). Antimicrobial activity of the ligand was investigated for its minimum inhibitory concentration (MIC) to several bacteria and yeast cultures. UV–Visible spectroscopy studies also shown that the ligand can bind calf thymus DNA (CT-DNA) electrostatic binding. In addition, DNA cleavage study showed that the ligand cleaved DNA without the need for external agents. Energetically most favorable docked structures were obtained from the rigid molecular docking of the compound with DNA. The compound binds at the active site of the DNA proteins by weak non-covalent interactions. The colorimetric response of the ligand in DMSO to the addition of equivalent amount of anions (F⁻, Br⁻, I⁻, CN⁻, SCN⁻, ClO₄⁻, HSO₄⁻, AcO⁻, H₂PO₄⁻, N₃⁻ and OH⁻) was investigated and the ligand was shown to be sensitive to CN⁻ anion.     

Layer‐by‐Layer Na3V2(PO4)3 Embedded in Reduced Graphene Oxide as Superior Rate and Ultralong‐Life Sodium‐Ion Battery Cathode

Na₃V₂(PO₄)₃ (NVP) is regarded as a promising cathode for advanced sodium‐ion batteries (SIBs) due to its high theoretical capacity and stable sodium (Na) super ion conductor (NASICON) structure. However, strongly impeded by its low electronic conductivity, the general NVP delivers undesirable rate capacity and fails to meet the demands for quick charge. Herein, a novel and facile synthesis of layer‐by‐layer NVP@reduced graphene oxide (rGO) nanocomposite is presented through modifying the surface charge of NVP gel precursor. The well‐designed layered NVP@rGO with confined NVP nanocrystal in between rGO layers offers high electronic and ionic conductivity as well as stable structure. The NVP@rGO nanocomposite with merely ≈3.0 wt% rGO and 0.5 wt% amorphous carbon, yet exhibits extraordinary electrochemical performance: a high capacity (118 mA h g^?1 at 0.5 C attaining the theoretical value), a superior rate capability (73 mA h g^?1 at 100 C and even up to 41 mA h g^?1 at 200 C), ultralong cyclability (70.0% capacity retention after 15 000 cycles at 50 C), and stable cycling performance and excellent rate capability at both low and high operating temperatures. The proposed method and designed layer‐by‐layer active nanocrystal@rGO strategy provide a new avenue to create nanostructures for advanced energy storage applications.     

Modification of nanocrystalline TiO2 coatings with molecularly imprinted TiO2 for uric acid recognition

Combining the surface modification and molecular imprinting technique, a novel piezoelectric sensing platform with excellent molecular recognition capability was established for the detection of uric acid (UA) based on the immobilization of TiO₂ nanoparticles onto quartz crystal microbalance (QCM) electrode and modification of molecularly imprinted TiO₂ (MIT) layer on TiO₂ nanoparticles. The performance of the fabricated biosensor was evaluated, and the results indicated that the biosensor exhibited high sensitivity in UA detection, with a linear range from 0.04 to 45 μM and a limit of detection of 0.01 μM. Moreover, the biosensor presented high selectivity towards UA in comparison with other interferents. The analytical application of the UA biosensor confirmed the feasibility of UA detection in urine sample.     

Ni-hemin metal–organic framework with highly efficient peroxidase catalytic activity: toward colorimetric cancer cell detection and targeted therapeutics

Background

Given the great benefits of artificial enzymes, a simple approach is proposed via assembling of Ni²⁺ with hemin for synthesis of Ni-hemin metal–organic-frameworks (Ni-hemin MOFs) mimic enzyme. The formation of the Ni-hemin MOFs was verified by scanning electron microscopy, Transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Energy-dispersive X-ray spectroscopy and UV–vis absorption spectroscopy. This novel nanocomposite exhibited surprising peroxidase like activity monitored by catalytic oxidation of a typical peroxidase substrate, 3,3,5,5′-tetramethylbenzidine, in the presence of H₂O₂. By using folic acid conjugated MOF nanocomposite as a recognition element, we develop a colorimetric assay for the direct detection of cancer cells.

Results

The proposed sensor presented high sensitivity and selectivity for the detection of human breast cancer cells (MCF-7) and Human Caucasian gastric adenocarcinoma. By measuring UV–vis absorbance response, a wide detection range from 50 to 10⁵ cells/mL with a detection limit as low as 10 cells/mLwas reached for MCF-7 cells. We further discuss therapeutics efficiency of Ni-hemin MOFs in the presence of H₂O₂ and ascorbic acid. Peroxidase-mimic Ni-hemin MOFs as reactive oxygen species which could damage MCF-7 cancer cells, however for normal cells (human embryonic kidney HEK 293 cells) killing effect was negligible.

Conclusions

Based on these behaviors, the developed method offers a fast, easy and cheap assay for the interest in future diagnostic and treatment application.

     

Ecosystem respiration and its controlling factors in a coniferous and broad-leaved mixed forest in Dinghushan, China

Accurate estimation of ecosystem respiration (R_eco) in forest ecosysteM_s is critical for validating terrestrial carbon models. Continuous eddy covariance measuremenT_s of R_eco were conducted in a coniferous and broad-leaved mixed forest located in Dinghushan Nature Reserve of southern China. R_eco was estimated and the controlling environmental factors were analyzed based on two years' data from 2003 to 2004. Major resulT_s included that: (1) R_eco was affected by soil temperature, soil moisture, canopy air temperature and humidity, where soil temperature at 5 cm depth was the dominant factor. (2) The exponential equation, Van't Hoff equation, Arrhenius equation and Lyold-Talor equation can be used to describe the relationship between R_eco and temperature factors with similar statistical significance, while Lyold-Talor equation was the most sensitive to the temperature index (Q₁₀). (3) The multiplicative model driven by soil temperature (T_s) and soil moisture (M_s) was more corresponsive to R_eco, which explained that there were more R_eco variations than Lyold-Talor equation, both for higher and lower M_s. However, there was no statistical difference between the two models. (4) Annually accumulated R_eco of the mixed forest in 2003 was estimated as 1100–1135.6 gC m^?2 a^?1 by using daytime data, which was 12%–25% higher than R_eco (921–975 gC m^?2 a^?1) estimated by using nighttime data. The resulT_s suggested that using daytime data to estimate R_eco can avoid the common underestimation problem caused by using eddy covariance methods. The study provides a basic method for further study on accurate estimation of net ecosystem CO₂ exchange (NEE) in the coniferous and broad-leaved mixed forest in southern China.     

Flow injection chemiluminescence determination of acetochlor and cartap-HCl in freshwater samples using an acidic KMnO4–rhodamine-B reaction system

A flow injection (FI) methodology using the acidic potassium permanganate (KMnO₄)–rhodamine-B (Rh-B) reaction with chemiluminescence (CL) detection was established to determine acetochlor and cartap-HCl pesticides in freshwater samples. Experimental parameters were optimized, and Chelex-100 cationic exchanger mini column and solid-phase extraction (SPE) were used as phase separation techniques. Linear calibration curves were observed for the standard solutions of acetochlor and cartap-HCl over the ranges 0.005–2.0 mg L⁻¹ [y = 1155.8x + 57.551, R² = 0.9999 (n = 8)] and 0.005–1.0 mg L⁻¹ [y = 979.76x + 14.491, R² = 0.9998 (n = 8)] with LODs and LOQs of 7.5 × 10⁻⁴ and 8.0 × 10⁻⁴ mg L⁻¹ (3σ blank) and 2.5 × 10⁻³ and 2.7 × 10⁻³ mg L⁻¹ (10σ blank), respectively, with an injection throughput of 140 h⁻¹. These methods were used to estimate acetochlor and cartap-HCl with or without the SPE procedure, respectively, in spiked freshwater samples. Results obtained were not significantly different at a 95% confidence level to those of other reported methods. Recoveries for acetochlor and cartap-HCl were obtained over the ranges 93–112% (RSD = 1.9–3.6%) and 98–109% (RSD = 1.7–3.8%), respectively. The most probable CL reaction mechanism was explored.     

Field studies of ammonia excretion in Aphanius iberus (Pisces; Cyprinodontidae): body size and habitat effects

The effects of body size and habitat variability on ammonia excretion rates (R_AMs) of Aphanius iberus were analyzed in situ for the first time. At hourly intervals during a 5‐h field experiment, ammonia excretion was measured in 75 mature specimens from three sampling sites (small creek, marine salt‐mine, and salt‐marsh) established in a gradient of water salinity (0–5; 35–40; 65–70‰). Our results showed a specific size dependence pattern of R_AMs in the reproduction period, which might reflect an effect of the reproductive effort. In addition, the results point to a significant decrease in mean R_AM values of each population from freshwater aquatic systems (3.81 ± 0.58 μmol g⁻¹ h⁻¹ in fish of 2.8 ± 0.3 mm total length, TL) to salt aquatic systems with significantly higher alkalinity (2.52 ± 0.35 μmol g⁻¹ h⁻¹ in fish of 3.1 ± 0.5 mm TL in marine salt‐mine; 1.98 ± 0.55 μmol g⁻¹ h⁻¹ in fish of 3.1 ± 0.4 mm TL in salt‐marsh). Due to the size‐dependent pattern, R_AM in different habitats cannot be compared directly; ancova , followed by residual compared analysis (regression‐related techniques), is seen as a valid method for this purpose. This work presents the first field data on ammonia excretion in the Aphanius genus and the flexible physiologic response characteristic of Cyprinodontids has been demonstrated.     

Internet of things-enabled photomultiplier tube- and smartphone-based electrochemiluminescence platform to detect choline and dopamine using 3D-printed closed bipolar electrodes

There is a growing demand to realize low-cost miniaturized point-of-care testing diagnostic devices capable of performing many analytical assays. To fabricate such devices, three-dimensional printing (3DP)-based fabrication techniques provide a turnkey approach with marked precision and accuracy. Here, a 3DP fabrication technique was successfully utilized to fabricate closed bipolar electrode-based electrochemiluminescence (ECL) devices using conductive graphene filament. Furthermore, using these ECL devices, Ru(bpy)₃²⁺/TPrA- and luminol/H₂O₂-based electrochemistry was leveraged to sense dopamine and choline respectively. For ECL signal capture, two distinct approaches were used, first a smartphone-based miniaturized platform and the second with a photomultiplier tube embedded with the internet of things technology. Choline sensing led to a linear range 5–700 μM and 30–700 μM with a limit of detection (LOD) of 1.25 μM (R² = 0.98, N = 3) and 3.27 μM (R² = 0.97, N = 3). Furthermore, dopamine sensing was achieved in a linear range 0.5–100 μM with an LOD = 2 μM (R² = 0.99, N = 3) and LOD = 0.33 μM (R² = 0.98, N = 3). Overall, the fabricated devices have the potential to be utilized effectively in real-time applications such as point-of-care testing.     

Elastic Sandwich‐Type rGO–VS2/S Composites with High Tap Density: Structural and Chemical Cooperativity Enabling Lithium–Sulfur Batteries with High Energy Density

Driven by increasing demand for high‐energy‐density batteries for consumer electronics and electric vehicles, substantial progress is achieved in the development of long‐life lithium–sulfur (Li–S) batteries. Less attention is given to Li–S batteries with high volume energy density, which is crucial for applications in compact space. Here, a series of elastic sandwich‐structured cathode materials consisting of alternating VS₂‐attached reduced graphene oxide (rGO) sheets and active sulfur layers are reported. Due to the high polarity and conductivity of VS₂, a small amount of VS₂ can suppress the shuttle effect of polysulfides and improve the redox kinetics of sulfur species in the whole sulfur layer. Sandwich‐structured rGO–VS₂/S composites exhibit significantly improved electrochemical performance, with high discharge capacities, low polarization, and excellent cycling stability compared with their bare rGO/S counterparts. Impressively, the tap density of rGO–VS₂/S with 89 wt% sulfur loading is 1.84 g cm^?3, which is almost three times higher than that of rGO/S with the same sulfur content (0.63 g cm^?3), and the volumetric specific capacity of the whole cell is as high as 1182.1 mA h cm^?3, comparable with the state‐of‐the‐art reported for energy storage devices, demonstrating the potential for application of these composites in long‐life and high‐energy‐density Li–S batteries.     

Glucose biosensor based on the room-temperature phosphorescence of TiO2/SiO2 nanocomposite

The direct immobilization of glucose oxidase (GOD) on TiO₂/SiO₂ nanocomposite and its application as glucose biosensor were investigated. The room-temperature phosphorescence of TiO₂/SiO₂ nanocomposite can be quenched by hydrogen peroxide (H₂O₂). The detection of glucose may be accomplished by monitoring the formation of hydrogen peroxide which generated in the oxidation process of glucose with the catalysis of GOD. To our surprise, by using a 96-hole polyporous plate accessory of fluorescence spectrophotometer, the biosensor exhibits excellent linear response to glucose concentrations ranging from 1.0 × 10⁻⁹ to 1.0 × 10⁻² M with a detection limit of 1.2 × 10⁻¹⁰ M. The TiO₂/SiO₂ nanocomposite can be used as both supporting material and signal transducer. The phosphorescence intensity and color of the biosensor change obviously and even could be observed with naked eyes by continuous addition of glucose. Based on the room-temperature phosphorescence of TiO₂/SiO₂ nanocomposite, a new method of solid substrate-room-temperature phosphorimetry (SS-RTP) for glucose determination is proposed. A glucose biosensor was fabricated with wide determination concentration range, low detection limit, high sensitivity, and fast response time. And the biosensor has been successfully applied to the determination of glucose in human blood serum. The coacervation of GOD enzyme and its interaction with TiO₂/SiO₂ nanocomposite enlarge the surface area and enhance the chemical stability of GOD. The nice biocompatibility, large surface area, good chemical stability and nontoxicity of the TiO₂/SiO₂ nanocomposite have made this material suitable for functioning as biosensor.     

Carbon losses due to soil warming: Do autotrophic and heterotrophic soil respiration respond equally?

Global warming has the potential to increase soil respiration (R_S), one of the major fluxes in the global carbon (C) cycle. R_S consists of an autotrophic (R_A) and a heterotrophic (R_H) component. We combined a soil warming experiment with a trenching experiment to assess how R_S, R_A, and R_H are affected. The experiment was conducted in a mature forest dominated by Norway spruce. The site is located in the Austrian Alps on dolomitic bedrock. We warmed the soil of undisturbed and trenched plots by means of heating cables 4 °C above ambient during the snow‐free seasons of 2005 and 2006. Soil warming increased the CO₂ efflux from control plots (R_S) by ∼45% during 2005 and ∼47% during 2006. The CO₂ efflux from trenched plots (R_H) increased by ∼39% during 2005 and ∼45% during 2006. Similar responses of R_S and R_H indicated that the autotrophic and heterotrophic components of R_S responded equally to the temperature increase. Thirty‐five to forty percent or 1 t C ha⁻¹ yr⁻¹ of the overall annual increase in R_S (2.8 t C ha⁻¹ yr⁻¹) was autotrophic. The remaining, heterotrophic part of soil respiration (1.8 t C ha⁻¹ yr⁻¹), represented the warming‐induced C loss from the soil. The autotrophic component showed a distinct seasonal pattern. Contribution of R_A to R_S was highest during summer. Seasonally derived Q₁₀ values reflected this pattern and were correspondingly high (5.3–9.3). The autotrophic CO₂ efflux increase due to the 4 °C warming implied a Q₁₀ of 2.9. Hence, seasonally derived Q₁₀ of R_A did not solely reflect the seasonal soil temperature development.