Research Advances on Fiber-Optic SPR Sensors with Temperature Self-Compensation.

The fiber-optic surface plasmon resonance sensor has very promising applications in environmental monitoring, biochemical sensing, and medical diagnosis, due to the superiority of high sensitivity and novel label-free microstructure. However, the influence of ambient temperature is inevitable in practical sensing applications, and even the higher the sensitivity, the greater the influence. Therefore, how to eliminate temperature interference in the sensing process has become one of the hot issues of this research field in recent years, and some accomplishments have been achieved. This paper mainly reviews the research results on temperature self-compensating fiber-optic surface plasmon sensors. Firstly, it introduces the mechanism of a temperature self-compensating fiber-optic surface plasmon resonance sensor. Then, the latest development of temperature self-compensated sensor is reviewed from the perspective of various fiber-optic sensing structures. Finally, this paper discusses the most recent applications and development prospects of temperature self-compensated fiber-optic surface plasmon resonance sensors.

Laser-induced dynamic alignment and nonlinear-like optical transmission in liquid suspensions of 2D atomically thin nanomaterials.

Nonlinear optical property of atomically thin materials suspended in liquid has attracted a lot of attention recently due to the rapid development of liquid exfoliation methods. Here we report laser-induced dynamic orientational alignment and nonlinear-like optical response of the suspensions as a result of their intrinsic anisotropic properties and thermal convection of solvents. Graphene and graphene oxide suspensions are used as examples, and the transition to ordered states from initial optically isotropic suspensions is revealed by birefringence imaging. Computational fluid dynamics is performed to simulate the velocity evolution of convection flow and understand alignment-induced birefringence patterns. The optical transmission of these suspensions exhibits nonlinear-like saturable or reverse saturable absorptions in Z-scan measurements with both nanosecond and continuous-wave lasers. Our findings not only demonstrate a non-contact controlling of macroscopic orientation and collective optical properties of nanomaterial suspensions by laser but also pave the way for further explorations of optical properties and novel device applications of low-dimensional nanomaterials.

Slowing designer surface plasmons in a surface-wave photonic crystal.

We propose and experimentally demonstrate a broadband slow-wave system in a surface-wave photonic crystal based on a non-uniform line-defect waveguide with graded metallic pillars, whose dispersions and cutoff frequencies vary gradually along the waveguide. Since the group velocity of designer surface plasmons at the cutoff frequencies is zero, we show that surface waves can be slowed and stopped at different positions under different frequencies. Experimental evidence including transmission measurements and direct near-field profile imaging performed in the microwave frequencies validate the stopping of surface waves in a broadband range within the forbidden bandgap of the surface-wave photonic crystal. This proposal is a promising candidate for slow-wave devices implemented on a single metal surface in both the microwave and terahertz frequency ranges.

Direct Observation of Landau Level Resonance and Mass Generation in Dirac Semimetal Cd3As2 Thin Films.

Three-dimensional topological Dirac semimetals have hitherto stimulated unprecedented research interests as a new class of quantum materials. Breaking certain types of symmetries has been proposed to enable the manipulation of Dirac fermions, and that was soon realized by external modulations such as magnetic fields. However, an intrinsic manipulation of Dirac states, which is more efficient and desirable, remains a significant challenge. Here, we report a systematic study of quasi-particle dynamics and band evolution in Cd3As2 thin films with controlled chromium (Cr) doping by both magneto-infrared spectroscopy and electrical transport. We observe the √B relation of inter-Landau-level resonance in Cd3As2, an important signature of ultrarelativistic massless state inaccessible in previous optical experiments. A crossover from quantum to quasi-classical behavior makes it possible to directly probe the mass of Dirac fermions. Importantly, Cr doping allows for a Dirac mass acquisition and topological phase transition enabling a desired dynamic control of Dirac fermions. Corroborating with the density-functional theory calculations, we show that the mass generation can be explained by the explicit C4 rotation symmetry breaking and the resultant Dirac gap engineering through Cr substitution for Cd atoms. The manipulation of the system symmetry and Dirac mass in Cd3As2 thin films provides a tuning knob to explore the exotic states stemming from the parent phase of Dirac semimetals.

Optically driven intelligent computing with ZnO memristor.

Artificial vision is crucial for most artificial intelligence applications. Conventional artificial visual systems have been facing challenges in terms of real-time information processing due to the physical separation of sensors, memories, and processors, which results in the production of a large amount of redundant data as well as the data conversion and transfer between these three components consuming most of the time and energy. Emergent optoelectronic memristors with the ability to realize integrated sensing-computing-memory (ISCM) are key candidates for solving such challenges and therefore attract increasing attention. At present, the memristive ISCM devices can only perform primary-level computing with external light signals due to the fact that only monotonic increase of memconductance upon light irradiation is achieved in most of these devices. Here, we propose an all-optically controlled memristive ISCM device based on a simple structure of Au/ZnO/Pt with the ZnO thin film sputtered at pure Ar atmosphere. This device can perform advanced computing tasks such as nonvolatile neuromorphic computing and complete Boolean logic functions only by light irradiation, owing to its ability to reversibly tune the memconductance with light. Moreover, the device shows excellent operation stability ascribed to a purely electronic memconductance tuning mechanism. Hence, this study is an important step towards the next generation of artificial visual systems.

Ruthenium containing molecular electrocatalyst on glassy carbon for electrochemical water splitting.

Electrochemical water splitting constitutes one of the most promising strategies for converting water into hydrogen-based fuels, and this technology is predicted to play a key role in the transition towards a carbon-neutral energy economy. To enable the design of cost-effective electrolysis cells based on this technology, new and more efficient anodes with augmented water splitting activity and stability will be required. Herein, we report an active molecular Ru-based catalyst for electrochemically-driven water oxidation (overpotential of ∼395 mV at pH 7 phosphate buffer) and two simple methods for preparing anodes by attaching this catalyst onto glassy carbon through multi-walled carbon nanotubes to improve stability as well as reactivity. The anodes modified with the molecular catalyst were characterized by a broad toolbox of microscopy and spectroscopy techniques, and interestingly no RuO2 formation was detected during electrocatalysis over 4 h. These results demonstrate that the herein presented strategy can be used to prepare anodes that rival the performance of state-of-the-art metal oxide anodes.

[Effect of periodontal initial therapy together with Chinese herbal compound for clearing heat and detoxification on interleukin-1 beta and tumor necrosis factor-alpha in gingival crevicular fluid of patients with chronic periodontitis].

OBJECTIVE: To observe the effect of periodontal initial therapy together with Chinese herbal compound for clearing heat and detoxification (Abbr. TCM) on the levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in gingival crevicular fluid (GCF) of patients with chronic periodontitis (CPD). METHODS: Thirty-four teeth of 24 patients with CPD were randomly assigned to the control group (17 teeth of 11 patients) and the treated group (17 teeth of 13 patients), they were treated for 8 weeks with periodontal initial therapy, but TCM was given additionally to the treated group. The GCF of the observed teeth was collected at the time before initial therapy (datum line) and at 2 and 8 weeks after treatment. At the same time, the clinical parameters, including probing depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP) were recorded, and the levels of TNF-alpha and IL-1 beta in GCF were measured by radioimmunoassay. RESULTS: The levels of TNF-alpha and IL-1 beta in GCF after treatment were significantly lowered in all patients as compared with those before treatment (P<0.01), while PD, CAL and BOP showed significant reduction (P<0.01). After treatment, TNF-alpha and IL-1 beta levels in the treated group were lower than those in the control group (TNF-alpha: 2.5551 +/- 1.0157 microg/L vs 3.4341 +/- 1.0762 microg/L, IL-1 beta: 0.1335 +/- 0.0216 microg/L vs 0.1471 +/- 0.0169 microg/L; P<0.05). CONCLUSION: TCM could enhance the effect of periodontal initial therapy in lowering TNF-alpha and IL-1 beta levels, which was attributed to reducing the inflammatory reaction of periodontal tissues.

Anomalous Charge State Evolution and Its Control of Superconductivity in M3Al2C (M = Mo, W).

The charge states of elements dictate the behavior of electrons and phonons in a lattice, either directly or indirectly. Here, we report the discovery of an anomalous charge state evolution in the superconducting M3Al2C (M = Mo, W) system, where electron doping can be achieved through "oxidation." Specifically, with the continuous removal of electron donor (Al) from the structure, we found an electron doping effect in the negatively charged transition metals. Over a certain threshold, the charge state of transition metals goes through a sudden reversion from negative to positive, which leads to a subsequent structure collapse. Concomitantly, the previous robust superconducting transition temperatures (Tcs) can be flexibly modulated. Detailed analysis reveals the origin of the superconductivity and the intimate relationship between the charge state and the electron-phonon coupling constant. The peculiar charge state in M3Al2C plays an important role in both its structure and superconductivity.

Ultra-high open-circuit voltage of tin perovskite solar cells via an electron transporting layer design.

Tin perovskite is rising as a promising candidate to address the toxicity and theoretical efficiency limitation of lead perovskite. However, the voltage and efficiency of tin perovskite solar cells are much lower than lead counterparts. Herein, indene-C60 bisadduct with higher energy level is utilized as an electron transporting material for tin perovskite solar cells. It suppresses carrier concentration increase caused by remote doping, which significantly reduces interface carriers recombination. Moreover, indene-C60 bisadduct increases the maximum attainable photovoltage of the device. As a result, the use of indene-C60 bisadduct brings unprecedentedly high voltage of 0.94 V, which is over 50% higher than that of 0.6 V for device based on [6,6]-phenyl-C61-butyric acid methyl ester. The device shows a record power conversion efficiency of 12.4% reproduced in an accredited independent photovoltaic testing lab.

Influence of substrates in ZnO devices on the surface plasmon enhanced light emission.

The substrates in emitting structure were found to have an influence on the surface plasmon mediated light emission of ZnO films. Ag film mediated photoluminescence was quenched for ZnO on silicon substrate but enhanced for ZnO on quartz or sapphire substrate. Through a theoretical simulation, the quenching for ZnO on silicon substrate is ascribed to the power lost to the substrate mode nonradiatively at the expense of the power coupled to the SP mode. The substrate with a high refractive index may capture and dissipate the emitting power which limits the efficiency of SP mediated light extraction. Therefore, a proper arrangement of the refractive index of the substrate and emitting layers in the device structure is decisive for the SP coupled light emission enhancement. Base on the theoretical analysis, a four-layered structure was advanced to recover SP mediated emission enhancement from ZnO film on silicon substrate.

Distinguishing thermal lens effect from electronic third-order nonlinear self-phase modulation in liquid suspensions of 2D nanomaterials.

The interaction of light with atomically thin nanomaterials has attracted enormous research interest in order to understand two-dimensional (2D) electron systems and develop novel opto-electronic devices. The observations of spatial self-phase modulation and the associated multiple diffraction ring patterns in liquid suspensions of 2D nanomaterials are believed to be excellent examples of strong laser interaction with 2D nanomaterials and this phenomenon has been attributed to their large electronic third-order susceptibilities. By performing a series of control experiments with liquid suspensions of graphene and graphene oxide flakes in different solvents at various temperatures under an increasing modulation frequency of laser illumination, we first show that the diffraction ring pattern has little dependence on the type of nanomaterial but strongly depends on the duration of laser illumination. A laser induced local refractive index change is then monitored by a weaker probe beam, resulting in the divergent diffraction of the probe beam that indicates a lower self-induced refractive index in the center of the pump laser beam than at its periphery: a clear signature of the thermal lens effect. Finally, we use computational fluid dynamics to simulate laser induced temperature and index changes of the suspensions. The evolution of diffraction rings is well correlated to the transient temperature distribution. Our understanding of complex laser interactions with nanomaterial suspensions and the associated thermal lens effect paves the way for further basic studies and fluid opto-electronic applications of 2D nanomaterials.

Weak antilocalization in Cd3As2 thin films.

Recently, it has been theoretically predicted that Cd3As2 is a three dimensional Dirac material, a new topological phase discovered after topological insulators, which exhibits a linear energy dispersion in the bulk with massless Dirac fermions. Here, we report on the low-temperature magnetoresistance measurements on a ~50 nm-thick Cd3As2 film. The weak antilocalization under perpendicular magnetic field is discussed based on the two-dimensional Hikami-Larkin-Nagaoka (HLN) theory. The electron-electron interaction is addressed as the source of the dephasing based on the temperature-dependent scaling behavior. The weak antilocalization can be also observed while the magnetic field is parallel to the electric field due to the strong interaction between the different conductance channels in this quasi-two-dimensional film.

[The expression of interleukin-10 mRNA in gingival lesion of different clinical states in patients with adult periodontitis].

OBJECTIVE: To investigate the expression of interleukin-10 (IL-10) mRNA in gingival tissue of active and stable stage in patients with adult periodontitis. METHODS: 12 patients with acute abscesses of the periodontium, 12 patients after periodontal initial treatment and 6 periodontal healthy patients having extraction of impacted wisdom tooth were randomly divided into group A (active stage group), group B (stable stage group) and the control group. Biopsies of gingival tissues were collected from every subject of three groups. Technique of in situ hybridization was applied to observe the expression of IL-10 mRNA in the biopsies from three groups semi-quantitatively. RESULTS: IL-10 mRNA was positively expressed in lymphocytes, macrophages and fibroblasts. The quantity of IL-10 mRNA of group A was the lowest in the three groups and was significantly lower than that of control group and group B respectively (P < 0.01). The quantity of IL-10 mRNA of group B was the highest in the three groups and was significantly higher compared with the control group and group A (P < 0.01). CONCLUSION: The quantities of IL-10 mRNA expression are closely related with various clinical states of periodontitis.

[Study on the expression of IL-10 mRNA and the protein in gingival tissues of patients with chronic periodontitis].

PURPOSE: To investigate the cell type which express IL-10 mRNA and the protein in gingival tissues of patients with chronic periodontitis. METHODS: 12 patients with chronic periodontitis who were undergoing flap operation were randomly chosen as periodontitis group;10 patients undergoing gingivectomy were chosen as gingivitis group;6 patients undergoing extraction of impacted teeth were chosen as control group. Assays of in situ hybridization and immunohistochemistry were used to observe the expression of IL-10 mRNA and the protein in gingival tissues of each group respectively . Wilcoxon test was used to compare the expression of IL-10 of each group at two levels; differences between the two groups were analyzed by one-way ANOVA test. RESULTS: IL-10 mRNA and the protein were all expressed in gingival tissues of periodontium,they were found in lymphocytes, fibroblasts and macrophages. There were no significant differences between two levels of IL-10 expression of periodontitis group and control group (P>0.05) gingivitis group,P<0.05). The IL-10 expression of periodontitis group was significantly higher than gingivitis group and control group (P<0.01); The IL-10 mRNA expression of periodontitis group was significantly higher than control group (P<0.01),but there was no significant difference between the IL-10 mRNA expression of periodontitis group and gingivitis group (P>0.05). CONCLUSION: There is a local secretion mechanism of IL-10 in the periodontal tissues.

[Observation of the clinical effects of two kinds of resin materials for restoring the defects of maxillary incisor].

To analyse and compare the effects of the resin materials of etched and nonetched groups in restoring the defect of maxillary incisor. 120 teeth were divided into two groups and filled by two kinds of materials. One year follow up results was studied. The effects of retention had no significant difference between the two groups, but the nonetched group had a lower stimulation to the pulp than the other one in restoring middle to deep caries. Compared to the etched group, the nonetched materials of resin has lower stimulation to pulp, more adhesion and higher success rate.