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Junfei Zhang,1,* Yuanxin Du,2,3,* Yongcai Zhang,4 Yanan Xu,5 Yanying Fan,2,3 Yan Li2,3 1Shanxi Provincial People’s Hospital Affiliated to Shanxi Medical University, Taiyuan, 030001, People’s Republic of China; 2Department of Pharmacology, Basic Medical Sciences Center, Shanxi Medical University, Taiyuan, 030001, People’s Republic of China; 3Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, 030001, People’s Republic of China; 4First Hospital of Shanxi Medical University, Taiyuan, 030001, People’s Republic of China; 5Medical Imaging Department of Shanxi Medical University, Taiyuan, 030001, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yan Li; Yanying Fan, Department of Pharmacology, Basic Medical Sciences Center, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, 56#, Xin Jian South Road, Taiyuan, Shanxi Province, 030001, People’s Republic of China, Email yxliyan@net.cn; fyanying6@hotmail.comBackground: Lung metastasis is a common metastasis site of colorectal cancer which largely reduces the quality of life and survival rates of patients. The discovery of potential novel diagnostic biomarkers is very meaningful for the early diagnosis of colorectal cancer with lung metastasis.Methods: In the present study, the metabonomic profiling of serum samples of lung metastasis mice was analyzed by 1H-nuclear magnetic resonance (1H-NMR). Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to elucidate the distinguishing metabolites between different groups, and all achieved excellent separations, which indicated that metastatic mice could be differentiated from control mice based on the metabolic profiles at serum levels. Furthermore, during lung metastasis of colorectal cancer, metabolic phenotypes changed significantly, and some of metabolites were identified.Results: Among these metabolites, approximately 15 were closely associated with the lung metastasis process. Pathway enrichment analysis results showed deregulation of metabolic pathways participating in the process of lung metastasis, such as synthesis and degradation of ketone bodies pathway, amino acid metabolism pathway and pyruvate metabolism pathway.Conclusion: The present study demonstrated the metabolic disturbances of serum samples of mice during the lung metastasis process of colorectal cancer and provides potential diagnostic biomarkers for the disease.Keywords: colorectal cancer, metastasis, metabolomics, biomarkers, 1H-NMR

The glutathione (GSH) level in human serum is closely associated with several life-threatening diseases, and tracing the aberrant GSH level can monitor the subhealth conditions at an early stage fo...

The thiol ligand-induced structural change is a good strategy to construct new metal nanoclusters. In this paper, ligand engineering was exploited to render reversible Cu–S motif transformation bet...

Despite the widespread use of bimetallic nanomaterial catalysts, a molecular-level understanding of the synergistic effects is unclear, limiting our ability to pre-design “tailor-made” bimetallic catalysts. We chose bimetallic Au1Ag24(SR)18 and Au25−xAgx(SR)18 (x = 2–6) nanoclusters (NCs) as models to investigate the relationship between microstructure and performance, comparing them with the corresponding monometallic NCs. Experimental and theoretical analyses demonstrated that the Au@Ag kernel was the essential structural feature for high activity and super stability of Au1Ag24(SR)18 catalyst in the alkynylation of CF3-ketone. This structure-activity relationship was successfully extended to other bimetallic systems bearing an Au@Ag kernel, such as Au12Ag32(SR)30 NC, and is thought to constitute a guiding principle for the intelligent design of high-performance bimetallic catalysts in the future.

As a promising new-star electrocatalyst, transition metal phosphide (TMP) has been widely applied in electrocatalytic hydrogen and oxygen evolution reactions (HER and OER). However, the current cat...

Improving the knowledge of the relationship between structure and properties is fundamental in catalysis. Recently, researchers have developed a variety of well-controlled methods to synthesize atomically precise metal nanoclusters (NCs). NCs have shown high catalytic activity and unique selectivity in many catalytic reactions, which are related to their ultrasmall size, abundant unsaturated active sites, and unique electronic structure different from that of traditional nanoparticles (NPs). More importantly, because of their definite structure and monodispersity, they are used as model catalysts to reveal the correlation between catalyst performance and structure at the atomic scale. Therefore, this review aims to summarize the recent progress on NCs in catalysis and provide potential theoretical guidance for the rational design of high-performance catalysts. First a brief summary of the synthetic strategies and characterization methods of NCs is provided. Then the primary focus of this review—the model ...

In catalysis, tuning the structural composition of the metal alloy is known as an efficient way to optimize the catalytic activity. This work presents the synthesis of compositional segregated six-armed PtCu nanostars via a facile solvothermal method and their distinct composition-structure-dependent performances in electrooxidation processes. The alloy is shown to have a unique six arms with a Cu-rich dodecahedral core, mainly composed of {110} facets and exhibit superior catalytic activity toward alcohols electrooxidation compared to the hollow counterpart where Cu was selectively etched. Density functional theory (DFT) calculations suggest that the formation of hydroxyl intermediate (OH*) is crucial to detoxify CO poisoning during the electrooxidation processes. The addition of Cu is found to effectively adjust the d band location of the alloy catalyst and thus enhance the formation of *OH intermediate from water splitting, which decreases the coverage of *CO intermediate. Our work demonstrates that the unique compositional anisotropy in alloy catalyst may boost their applications in electrocatalysis and provides a methodology for the design of this type catalyst.

Herein, the ligands’ effect in Cu(I) clusters was initially explored. The results demonstrate that the Se atom possesses more coordination modes with Cu (μ2, μ3, μ4, μ6) than S, which significantly modulates the atom-packing mode of Cu(I) clusters. Importantly, this also endows these clusters with different temperature-dependent luminescent behaviours.

Ultra-long YCe x O y :Eu 3+ nanowire arrays(NWAs) have been synthesized in anodic aluminum oxide (AAO) templates by chemical co-deposition at negative pressure suction, which are amorphous, and possess precise dimension and homogeneous morphologies. The SEM, TEM, XRD and EDS were employed to investigate the morphology, structure and elemental composition of YCe x O y :Eu 3+ NWAs. The fluorescence properties of the YCe x O y :Eu 3+ NWAs were measured by fluorescence spectrometer (PerkinElmer LS-55) using Xenon discharge lamp as the excitation light source. There are two emission peaks at 615 nm and 702 nm with excitation wavelength of 394 nm, which corresponds to the 5 D 0 - 2 F 2 and 5 D 0 - 7 F 4 energy level transition of Eu 3+ , respectively. The fluorescence intensity of YCe x O y :Eu 3+ NWAs is related to the doping concentration of Eu 3+ ion, which reaches a maximum with doping concentration of Eu 3+ at 8%, and remarkably decreases at higher concentrations. Ce 3+ ion dominates the fluorescence activation in YCe x O y :Eu 3+ NWAs.

In this work, we utilized a facile air oxidative dealloying approach to synthesize PtCu hierarchical branched nanodendrites (HBNDs). The systematical investigation on the morphology, composition, and structure of PtCu HBNDs by various techniques demonstrates they are three-dimensional open porous nanostructures. The PtCu HBNDs show composition-dependent catalysis in hydrogen evolution reaction (HER). The Pt1Cu1.03-D with average size about 40 nm composed of integrated ultrathin branches, presents the highest HER activity with only 20 mV overpotential to achieve 10 mA/cm2, 19.34 A/mgPt and 9.64 mA/cm2 in mass and specific activity at −0.2 V, and excellent durability. The superior HER activity is attributed to the unique porous dendritic structure and electronic synergistic interactions between Pt and Cu as indicated by X-ray photoelectron spectroscopy and density functional theory calculation. This work opens up a new facile route to design large accessible surface and high-performance electrocatalysts with low utilization of Pt for electrochemical energy conversion.

Atomically precise nanoclusters (NCs) have been widely used as catalysts in many reactions to investigate the structure–activity relationship due to their ultrasmall sizes, well-defined structures and precise compositions, especially bimetallic NCs can further promote the catalytic activity by the synergistic effects of heteroatoms. For electrocatalytic hydrogen evolution reaction (HER) catalysts, a common method to improve the performance is coupling with a nano-metal, but the origin of the enhancement is still unclear due to the diversity and complexity of the nanometal supported composites. Here, we take MoS2 (a star HER electrocatalyst) as an example, to report a strategy to boost the activity and give insight into the activity enhancement of it by combining with bimetallic atomically precise NCs. The crystal structure of this new NC is determined by X-ray crystallography, and its precise composition is identified as Au2Pd6S4(PPh3)4(C6H4F2S)6 (Au2Pd6 for short). The Au2Pd6/MoS2 show significantly improved HER activity and robust durability compared to the single component Pd3 or Au2/MoS2 and bare MoS2. This is attributed to the appropriate adsorption behavior of H atoms on Au2Pd6/MoS2 and the electronic interactions between NCs and MoS2, according to the combination of experiment and theory. This study presents a new strategy to improve the electrocatalytic activity of 2D materials such as MoS2 and sheds light on the origin of the promotion effects at the atomic level.

The introduction of Ag+ results in significant amplification of the fluorescence signal of water-soluble gold nanoclusters (NCs) capped by BSA (short for bull serum albumin) associated with a blueshift of the emission maximum by about 35 nm. In contrast, all other metal ions and anions (Au3+, Ca2+, Mn2+, NO2−, F−, Cl−, etc.) induce comparable emission intensities, and Hg2+ completely quenches the emission of gold NCs. The amplified fluorescence is used to recover the fluorescence in sensing systems of Hg2+ based on gold nanoclusters, amplifying the emission signal and improving the detection limits.

Hydrolysis reaction of ammonia borane (AB) has been considered as a safe and efficient hydrogen generation method, in which designing cost-effective and high-performance catalysts plays vital role. In this work, we have developed well dispersed palladium-nickel hollow nanospheres (PdNi HNSs) with tunable shell thickness and compositions via a facile galvanic replacement approach. The as-prepared PdNi HNSs show composition-dependent catalysis in the hydrolytic dehydrogenation of AB. The Pd84Ni16/C exhibiting sphere-shaped hollow interiors with average 70 nm particle size and 10 nm thin wall, presents the highest catalytic activity with the turnover frequency of 76.0 (mol H2 min−1 (mol Pd)−1) and the activation energy of 33.5 kJ mol−1. The superior catalytic effect of PdNi HNSs in enhancing hydrolysis efficiency of AB can be ascribed to two major factors: (1) high active surface areas of the unique hollow structure; (2) enhanced H adsorption attributed to the coupling between Pd and Ni induces polarization charges on Pd catalytic sites, which is indicated by the first-principles calculation and X-ray photoelectron spectroscopy studies. Furthermore, the catalysts exert good long-term recycling stability and catalytic activity for the hydrolytic dehydrogenation of AB. This work represents a strategy may hopefully be extended to synthesize other Pd-based hollow nanostructure with reduced Pd usage and increased catalytic active sites, and also sheds light on the exploration of utilizing interatomic interactions to regulate species adsorption/activation for highly efficient catalytic performance.

Controlled encapsulation of atomically precise nanoclusters (APNCs) into metal–organic frameworks (MOFs) has been an efficient way to create new types of multifunctional crystalline porous materials. Such hybrids (APNCs@MOFs) provide ideal candidates for studying inherent structure–catalysis relationships owing to the well-defined compositions of both components. Moreover, modeling of APNCs@MOFs with precise structures would be more reliable. Herein, we have established an “Electrostatic Attraction Strategy” to synthesize APNCs@MOF catalysts and studied their performance as catalysts for the conversion of CO2. The synthetic strategy presented here has been proved to be general, as evidenced by the syntheses of various APNCs@MOF catalysts including all the combinations of [Au12Ag32(SR)30]4−, [Ag44(SR)30]4−, and [Ag12Cu28(SR)30]4− nanoclusters with ZIF-8, ZIF-67, and MHCF frameworks. In particular, the as-obtained Au12Ag32(SR)30@ZIF-8 composite shows excellent performance in capturing CO2 and converting phenylacetylene into phenylpropiolate under mild conditions (50 °C and ambient CO2 pressure) with a TON as high as 18 164, far exceeding those of most known catalysts. What's more, the catalyst is very stable and reused 5 times without loss of catalytic activity. We anticipate that this general synthetic approach may open up a new frontier in the development of promising APNCs@MOF catalysts, which can be applied in a broad range of heterogeneous catalyses in the future.

With slowing economic growth and outstanding environmental problems in China, the government proactively adopting environmental regulation (ER) to promote green technology advancement is the key to solving the dilemma of environment and economy, which is of great significance to the sustainable development, also set an example for other emerging economies. This study probed the impact of ER on the green innovation efficiency (GIE) from the perspective of spatial correlation of the prefecture-level cities in China on the base of theoretical analysis. Firstly, the GIE of the cities was calculated by a special data envelopment analysis (DEA) called super slacks-based measure (Super-SBM) and taking undesirable output in account, and the comprehensive index of the ER was calculated by entropy method. Secondly, this study established a spatial model to test the effect of ER on the GIE in a city, and examined the direct, indirect and total spatial effects. Finally, this study attempted to explain the spatial effect from the perspective of financial ability between enterprises and fiscal decentralization between regions. The empirical results showed as flowing: (1) GIE has declined first and then increased from 2008 to 2015 in China, which is highest in the east and lowest in the central. (2)The spatial spillover effect of ER on the GIE is significant, which was a U-shaped impact that suppressed firstly and then promoted, regardless of local-effect or neighboring-effect. (3) Shorter official tenure and lower enterprises’ profitability have weaken the impact of ER on the GIE. The government should strengthen regional cooperation, improve the public environmental supervision mechanism, and formulate stringent but differentiated ER based on local conditions.

Recently, transition metal phosphides (TMPs) have been reported as a new kind of anode catalyst for oxygen evolution reaction (OER), and the composition of the material largely determines the performance of the catalysts. However, few reports explore how electrocatalytic performance of TMPs changed with the composition of the catalysts. We selected three different component Fe-based Prussian blue analogues (PBA) as precursors and transformed them into corresponding metal phosphides by simple heat treatment. By tuning the phosphidation temperature, a series of FeCoP, FeNiP, and FeMnP were obtained, in which FeCoP under a suitable phosphidation temperature at 400 °C exhibits most obviously porous structure and broadest distribution of pore size, which benefits for the mass transfer and oxygen release during OER. Besides, the charge-transfer resistance (Rct) of TMPs has greatly decreased by introducing of Co in comparison of Ni and Mn, which accelerate the electron transport in OER. Due to the porous geometric structure and unique electronic structure, FeCoP-400 shows excellent and stable electrocatalytic activities of OER in 1 M KOH, with overpotentials of 261 mV at a current density of 10 mA cm−2, superior to commercial RuO2 and most OER electrocatalysts. Furthermore, FeCoP-400 exhibits outstanding stability with only 4% increase in potential during 24 h chronopotentiometry.

Chemically-triggered drug delivery systems (DDSs) have been extensively studied as they do not require specialized equipment to deliver the drug and can deeply penetrate human tissue. However, their syntheses are complicated and they tend to be cytotoxic, which restricts their clinical utility. In this work, the self-regulated drug loading and release capabilities of peptide-protected gold nanoclusters (Pep-Au NCs) are investigated using vancomycin (Van) as the model drug. Gold nanoclusters (Au NCs) coated with a custom-designed pentapeptide are synthesized as drug delivery nanocarriers and loaded with Van - a spontaneous process reliant on the specific binding between Van and the custom-designed peptide. The Van-loaded Au NCs show comparable antimicrobial activity with Van on its own, and the number of Van released by the Pep-Au NCs is found to be proportional to the amount of bacteria present. The controlled nature of the Van release is very encouraging, and predominantly due to the stronger binding affinity of Van with bacteria than that with Au NCs. In addition, these fluorescent Au NCs could also be used to construct temperature sensors, which enable the in vitro and in vivo bioimaging.

The interface of electrodes composed of 2, 3, or 5 monolayers (MLs) of graphene stacked on a Si prism in 0.1 M HClO4 is examined by electrochemical in situ infrared spectroscopy under attenuated total reflection configuration (EC-ATR-FTIRS) combined with cyclic voltammetry in a wide potential window from 0 to 3. 0 V. At 5 MLs graphene, we observe significant oxidation current at E > 2.0 V in the first positive-going scan. This is accompanied by the appearance of three negative-pointing bands at 1230 cm–1 (C-O-C stretching), 1630 cm–1 (from both bending of water and C═C stretching), and 3300 cm–1 (O-H stretching of C-OH and water), suggesting the consumption of C-O-C, C═C, C-OH, and water. The CVs for the second cycle are quite similar to what was observed for the first cycle, only that the current is ca. 10 times smaller. The general trends of the i–E curves and IR spectral behavior at 2 MLs and 3 MLs graphene are also the same as those at 5 MLs graphene; only the current and band intensities at the corre...

Hematite (α-Fe2O3) nanoparticles are deposited onto porous ‘activated microwave expanded graphite oxide’ (aMEGO) carbon via a simple, rapid one-pot microwave process. Under the irradiation of visible light, the α-Fe2O3/aMEGO composites exhibit significantly enhanced photocatalytic activity for the reduction of Cr(VI) to Cr(III). A maximum Cr(VI) removal rate of 95.28% is obtained for the composite containing 7.72 wt% aMEGO as compared to that of 25.26% for pure α-Fe2O3; the rate constant of the composite is nearly 9 times higher than that of pure α-Fe2O3. The crucial role of aMEGO in enhancing the photocatalytic efficiency of the composites relies not only on its large surface area, but also on the high conductivity which benefits the transport of photoexcited electrons. The enhancement in the charge separation and the suppression in the electron–hole pair recombination is evidenced by an increased photocurrent and a suppressed photoluminescence in the α-Fe2O3/aMEGO composites.

The interactions between visible light and sub-nanometer gaps were investigated by sandwiching graphene between two layers of vertically stacked Au nanoparticles. The optical properties of such a hybrid film have been effectively tuned by embedding a monolayer graphene, enabling a suppressed transmission of ∼16% accompanied by a red-shift of the resonant wavelength. Finite element simulations have shown that the strong coupling between two layers of plasmonic Au nanoparticles leads to an electric field enhancement of up to 88 times in graphene defined vertical gaps, in contrast to that of 14 times in the horizontal gaps between Au nanoparticles formed in the fabrication process. In addition, the size of gaps and thus the field enhancement can be readily tuned by the number of graphene layers sandwiched between Au nanoparticles. When being used as surface-enhanced Raman scattering (SERS) substrates, the Au nanoparticle/graphene/Au nanoparticle structures have demonstrated high Raman enhancement factors of up to 1.6 × 10(8) for RhB and 2.5 × 10(8) for R6G, and a detection limit of as low as 0.1 nM for Sudan III and methylene blue molecules.

By simply coating graphene films on Au nanoparticles, the optical properties of the hybrid films are investigated. It is found that the coverage of a monolayer graphene film leads to a decreased transmittance of up to 15.8% in the visible range, much higher than the 2.3% transmittance loss for intrinsic graphene. At the same time, the plasmonic resonance of the hybrid films experiences a red-shift in resonance frequency and a broadening in the transmission dip. By means of finite element simulations, these observations are attributed to strong light–matter interaction at the interface between graphene and Au nanoparticles, as indicated by the increased absorption cross section and higher electric field intensity. The electron transfer between graphene and Au nanoparticles is confirmed by high resolution X-ray photoelectron spectroscopy studies. Furthermore, the enhanced electromagnetic hot spots at the interface between graphene and Au nanoparticles make such graphene–Au nanoparticle hybrid films cost-effective and high-performance surface-enhanced Raman scattering substrates for detecting organic molecules such as rhodamine-6G, for which an enhancement factor of ∼107 is achieved.

A lithium iron phosphate (LFP)/reduced graphene oxide (rGO) hybrid has been prepared using a homogeneous coprecipitation method followed by heat treatment. As a cathode material for the lithium ion battery, the hybrid demonstrates a specific capacity higher than 170 mA h g−1. The excess capacity of more than the theoretical value of LFP is attributed to the reversible reduction–oxidation reaction between lithium ions and rGO nanosheets. The highly conductive rGO sheets upon which LFP particles are uniformly and closely anchored assist in the electron migration and lithium ion transfer and prevent the aggregation of LFP particles during charging and discharging, leading to an initial coulombic efficiency of more than 100% with the content of rGO between 7% and 25% in the hybrid. LFP with 15% rGO shows a high discharge capacity of 172 mA h g−1 at 0.06 C, and the capacity remains 139 mA h g−1 at 11.8 C, in addition to showing an excellent cycling stability.

A high-speed broadband tunable microwave source utilizing the wavelength tunable characteristics of distributed Bragg reflector (DBR) laser is proposed and demonstrated. The wavelength tuning of the laser is achieved instantaneously by controlling the voltage of the phase section of the DBR laser. By means of optical delay self-heterodyne technology, the microwave signal with the property of frequency broadband tuning is generated. Sweep speeds of 5 and 40 μs of the sweep-frequency source prototype were achieved and the maximum tuning range was up to 38.45 GHz.

A selectable infiltrating large hollow core photonic band-gap fiber is fabricated with simple arc discharge technique. The offset, discharge duration, arc current and discharge times are optimized for selected sealing side air-holes but leave the central large air-hole partially open. The collapse length of the PCF is shortened by increasing the number of discharges and offset with discharge duration and arc current kept at a relatively low level. Light with the wavelength located at the photonic band-gap can still propagate while the central hollow air-hole is infiltrated with a kind of oil with refractive index of 1.30. The selectable infiltrating large hollow core photonic band-gap fiber has potential application for implementing novel lasers, sensors and tunable optoelectronic devices.

A simple edge-triggered and chirp-free ultra-wideband (UWB) monocycle pulse shaper was proposed and demonstrated utilizing a nonlinearly operated polarization-to-intensity converter, which mainly consists of a polarization modulator (PolM), two polarization controllers (PCs), and a time-delay device. As static phase shift of the incident light φ0=π, a 500-MHz monocycle pulse sequence with 10-dB bandwidth of 10 GHz and fractional bandwidth of 133% was obtained while a 250-MHz electrical quasi-square-wave was applied on the PolM. In addition, polarity switch of the UWB monocycle pulse can be realized by adjusting the bias voltage of the PolM or controlling the PC.

A total of 168 PM10 samples were collected during the year of 2005 at eight sites in the city of Wuxi in China. Fifteen chemical elements, three water-soluble ions, total carbon and organic carbon were analyzed. Six source categories were identified and their contributions to ambient PM10 in Wuxi were estimated using a nested chemical mass balance method that reduces the effects of colinearity on the chemical mass balance model. In addition, the concentrations of secondary aerosols, such as secondary organic carbon, sulfate and nitrate, were quantified. The spatially averaged PM10 was high in the spring and winter (123 μg·m−3 and low in the summer-fall (90 μg·m−3). According to the result of source apportionment, resuspended dust was the largest contributor to ambient PM10, accounting for more than 50% of the PM10 mass. Coal combustion (14.6%) and vehicle exhaust (9.4%) were also significant source categories of ambient PM10. Construction and cement dust, sulfates, secondary organic carbon, and nitrates made contributions ranging between 4.1% and 4.9%. Other source categories such as steel manufacturing dust and soil dust made low contributions to ambient PM10.

AlGaInAs/InP hexagonal resonator microlasers with an output waveguide connected to one vertex of the hexagon are fabricated using standard photolithography and inductively coupled plasma (ICP) etching process. Room-temperature continuous-wave electrically injected operation with a threshold current of 18 mA is realized for a hexagon laser with an edge length of 16 μm and an output waveguide width of 2 μm. Single-mode operation is achieved with a side mode suppression ratio of 21 and 33 dB at the injection current of 30 and 60 mA, respectively. The peak wavelength intervals of the laser spectrum agree very well with the longitudinal mode intervals of the whispering-gallery modes, which indicates single transverse mode operation. The mode Q factor of 6.53 × 103 is measured for the lasing mode at 1547 nm at the threshold current, which is in the same magnitude as the Q factor obtained by finite-difference time-domain (FDTD) simulation. The numerical simulations also indicate that the hexagonal resonator with an output waveguide is suitable to realize single transverse mode operation.

A simple widely-tunable and background-free ultra-wideband (UWB) pulse shaper by utilizing the polarization modulation-based optical switch is proposed and demonstrated. By virtue of the excellent switch isolation and the complementarity between two inverted baseband signals output from the optical switch, the local oscillator leakage signal and the low frequency components of the obtained UWB signals are suppressed very well. The UWB pulse with center frequency up to 28 GHz is generated.

We detail a facile method for enhancing the Raman signals of as-grown graphene on Cu foils by depositing gold nanoislands (Au Nis) onto the surface of graphene. It is found that an enhancement of up to 49 fold in the graphene Raman signal has been achieved by depositing a 4 nm thick Au film. The enhancement is considered to be related to the coupling between graphene and the plasmon modes of Au Nis, as confirmed by the finite element simulations. The plasmonic effect of the Au/graphene/Cu hybrid platform leads to a strong absorption at the resonant wavelength whose position shifts from visible light (640 nm) to near-infrared (1085 nm) when the thickness of Au films is increased from 2 nm to 18 nm. Finally, we demonstrate that hybrid substrates are reliable surface-enhanced Raman scattering (SERS) systems, showing an enhancement factor of ∼10(6) for dye molecules Rhodamine B and Rhodamine 6G with uniform and stable response and a detection limit of as low as 0.1 nM for Sudan III and Sudan IV.

Lithium vanadium phosphate (Li3V2(PO4)3, LVP)/reduced graphene oxide (rGO) composite is prepared with a rheological method followed by heat treatment. The size and interface of LVP particles, two important merits for a cathode material, can be effectively tuned by the rGO in the composite, which plays as surfactant to assist sol-gelation and simultaneously as conductive carbon coating. As a consequence, the composite with 7.0 ± 0.4 wt.% rGO shows a capacity of 141.6 mAh g(-1) at 0.075 C, and a rate capacity of 119.0 mAh g(-1) at 15 C with respect to the mass of LVP/rGO composite, and an excellent cycling stability that retains 98.7% of the initial discharge capacity after 50 cycles. The improved electrochemical performance is attributed to the well-controlled rGO content that yields synergic effects between LVP and rGO. Not only do the rGO sheets reduce the size of LVP particles that favor the Li(+) ion migration and the electron transfer during charging and discharging, but also contribute to the reversible lithium ions storage.

The chemical sensing for the convenient detection of mercuric ion (II) (Hg(2+)) have been widely explored with the use of various sensing materials and techniques. It still remains a challenge to achieve ultrasensitive but simple, rapid, and inexpensive detection to metal ions. Here we report a surface-enhanced Raman scattering (SERS) chip for the femtomolar (fM) detection of Hg(2+) by employing silver-coated gold nanoparticles (Au@Ag NPs) together with an organic ligand. 4,4'-Dipyridyl (Dpy) can control the aggregation of Au@Ag NPs via its dual interacting sites to Ag nanoshells to generate strong Raman hot spots and SERS readouts. However, the presence of Hg(2+) can inhibit the aggregation of Au@Ag NPs by the coordination with Dpy, and as a result the SERS signals of Dpy are quenched. On the basis of these findings, a SERS chip has been fabricated by the assembly of Au@Ag NPs on a piece of silicon wafer and the further modification with Dpy. The exchange of Dpy from the chip into the aqueous Hg(2+) droplet results in the quenching of Raman signals of Dpy, responding to 10 fM Hg(2+) that is about 6 orders of magnitude lower than the limit defined by the U.S. Environmental Protection Agency in drinkable water. Each test using the SERS chip only needs a droplet of 20 μL sample and is accomplished within ∼4 min. The SERS chip has also been applied to the quantification of Hg(2+) in milk, juice, and lake water.

The dynamic control for the spectra of the Ultra-wideband (UWB) signals, which is the key for implementing the dynamic spectrum access in the cognitive radio, is still a challenge due to the limited processing speed of the electronic devices. In this paper, we have summarized our recent work about controlling the spectrum shape of the UWB signals in optical domain, in addition to reviewing the other groups’ related research work. The experiment setups and results based on nonlinear dynamics of the optoelectronic oscillator and transfer response of the phase or polarization-to-intensity convertor will be described in detail respectively, in which the controllable frequency suppress for the optical UWB signals at specific frequency positions were implemented. Particularly, the UWB pulse with the special shape, which corresponds to the 5-GHz band-rejection in frequency domain, was generated in order to avoid the interference between UWB and Wireless Fidelity system in practice. In addition, the UWB signals whose center frequency could be continuously tuned and converted up to the frequency range of millimeter wave were generated by utilizing the polarization modulator based optical switch. The areas for future development and the challenge of implementing these techniques for the applications in practice will also be discussed.

A photonic approach to generating ultrawideband (UWB) pulses with tunable band-rejection behavior and a chirp-free property, which is based on a nonlinear operated polarization-to-intensity converter, is proposed and demonstrated. As an initial phase shift of the incident light φ0 = π, a high-order UWB pulse fully satisfied the indoor mask regulated by the Federal Communications Commission was synthesized by a pair of polarity-inverted and doublet-like pulses at the output port of the polarization beam combiner. Moreover, the notch band will occur dynamically on the power spectra of the UWB signals from 3 to 16 GHz through adjusting the relative delay time between both doublet-like pulses from 333 to 62.5 ps due to the effect of microwave photonic filtering, which means that the spectrum-overlay-induced interference between UWB and other narrow-band communication systems could be real-time averted. In addition, the polarity switch of the synthesized UWB pulse could be implemented by adjusting angle α between the x-axis component of modulated light and the principal axis of the arm of transverse electric mode by the polarization controller.