Search

Self-lubricating polyphenylene sulfide (PPS) composites were fabricated by constructing a segregated network structure using the co-deposition method. Both carboxyl-functionalized multi-walled carbon nanotubes (CNTs) and silicon carbide (SiC) were successfully coated on the surface of PPS powders with the aid of self-polymerization of dopamine (PDA) and co-polymerization between PDA and polyethyleneimine (PEI), thereby forming PPS@PDA-CNTs-SiC hierarchical reinforcing hybrids. Results showed that the thermal conductivity of PPS@PDA-CNTs-SiC (0.97 W/(m K)) is about 120% higher than that of PPS/CNTs/SiC. The friction coefficient (0.193) and specific wear rate (2.50 × 10−5 mm3/(N m)) of PPS@PDA-CNTs-SiC are 18.9% and 50% lower than those of PPS/CNTs/SiC, respectively. The enhanced thermal conductivity of PPS@PDA-CNTs-SiC contributes to rapid dissipation of frictional heat at the sliding interface which protects the polymer substrate from being destroyed or peeled, thereby improving the tribological performance. This work provides new insights into expanding the application of self-lubricating polymer composites in the fields where efficient heat dissipation is also a primary concern.

P2-type Na0.67Ni0.25Mn0.75O2 is considered as one of the most promising cathode materials for sodium-ion batteries due to its high initial capacity and operating voltage based on the Ni2+/Ni4+ redox reaction. However, it suffers from rapid capacity decay caused by P2–O2 phase transition when the cutoff voltage is above 4.2 V (vs. Na+/Na). Herein, a high-voltage phase transition from P2 to an amorphous phase with poor crystallinity has been proved to be the main cause of material deterioration and Mn redox process is another cause. Cu-substituted Na0.67(Ni0.25Mn0.75)1−xCuxO2 (x = 0, 0.05, 0.1, 0.2) with active redox couples of Ni2+/Ni4+ and Cu2+/Cu3+ has been fabricated for solving these issues. It is proved that Cu substitution can reduce the Mn3+/Mn4+ reaction below 3 V (vs. Na+/Na) and suppress the high-voltage phase transition effectively at deep de-sodiated state, resulting in the significantly enhanced cycle life and rate capability of Na0.67Ni0.25Mn0.75O2.

The enthalpy transformation method, a widely accepted way to solve the phase transition related problems, was utilized to investigate the relationship between solidification behavior and crystalliz...

Ni-rich LiNi0.8 Co0.15 Al0.05 O2 (NCA) material attracts extensive attention due to its high discharge specific capacity, but its distinct drawbacks of rapid capacity decline and poor cycle performance at elevated temperatures and high voltage during charge/discharge cycling restricts its widespread application. To solve these problems, a multifunctional coating layer composed of a lithium-ion-conductive lithium polyacrylate (LiPAA) inner layer and a cross-linked polymer outer layer from certain organic substances of silane-coupling agent (KH550) and polyacrylic acid (PAA) is successfully designed on the surface of NCA materials, which is favorable for eliminating residual lithium and improving lithium-ion conductivity, surface stability, and hydrophobicity of NCA materials. In addition, the amount of the coating material is also investigated. A series of characterization methods such as XRD, FTIR, SEM, TEM, and X-ray photoelectron spectroscopy are used to analyze the morphologies and structures for materials of pristine and modified NCA. It is revealed that the co-coating layer plays a vital part in reducing the surface residual alkalis and improving the stability of NCA particles; as a result, the modified NCA exhibits a greatly improved rate capability, cycle performance, and low polarization impedance.

In this study, a series of polyethylene thin films were prepared by thermally induced phase separation (TIPS) method with di(2-ethylhexyl)phthalate as the diluent. Morphological observations showed that the microstructures at different locations were fairly distinct and could generally be divided into three layers. When the polymer concentration was lower than the monotectic point (Φm), both pore size and porosity in TIPS films were heavily determined by growth time and growth rate of the diluent droplets. At relatively higher polymer concentration, cooling rate heavily affected the pore size in the films primarily through its influence on polymers’ crystallization process. The relationship between the film microstructure and cooling rate was quantitatively investigated (especially the effect of quenching conditions on the evolution of film morphology) with the aid of an enthalpy transformation method, which established the three-dimensional temperature profiles and supplied an insight into the competition between phase separation kinetics and polymer crystallization. In addition, our findings showed that the pore size, porosity and thermal stability of films all increased with an increasing quenching temperature, which was significantly different from the trends of variation in water vapor transmission rate as well as the $$ E^{\prime}_{ \hbox{max} } $$ and $$ E^{\prime\prime}_{ \hbox{max} } $$ values of dynamic mechanical analysis as the quenching temperature increased. The present work presents a facile way of in situ tailoring hierarchical microstructures in TIPS films of crystalline polymers, which will be very useful to the design of polymer porous films with specific properties.

In this study, we prepare series of low-density polyethylene (LDPE)/recycled polyethylene terephthalate (RPET) blends using melt extrusion. The effects of RPET content on the crystallization behavior and thermal conductive properties of the resultant blends were investigated using DSC, XRD, DMTA, TGA, etc. RPET was found to exert nucleating effect on the melt crystallization of LDPE without changing LDPE's crystal form. A four-parameter model (FPM) was adopted coupled with an in-situ temperature measurement to further disclose the solidification kinetics of LDPE in the presence of RPET. Among three thermal conduction models, the Agari model presented a reasonable prediction of thermal conductivity as a function of LDPE loading. A coefficient of cooling rate (CCR) is proposed and can be applicable as an indicator for thermal conductivity (λ) of the polymer blends. Keywords: Melt blending, Crystallization kinetics, Low-density polyethylene (LDPE), Recycled polyethylene terephthalate (RPET), Thermal conductivity

Automatic identification system (AIS) can provide massive ship trajectory data that is valuable for mining information in water traffic. However, large sizes lead to difficulties in storing, querying, and processing the aforementioned data. In the present study, to better compress ship trajectory data regarding compression time and efficiency, a method based on the improved Douglas–Peucker (DP) algorithm is presented. In the process of compression, the proposed method considers the shape of vessel trajectory derived from course information of track points. Parallel experiments are conducted based on AIS data gathered over the duration of a month in the Chinese Zhou Shan islands. The results indicate that this method can effectively compress ship trajectory information. Additionally, when compared with the traditional DP algorithm, this method can significantly reduce the compression time and exhibits better performance at high compression strengths. Also, the proposed method outperforms other existing trajectory compression algorithms in term of compression time.

There is growing evidence that motherwort (Leonurus japonicus Houtt.), and Chinese patent medicines derived from motherwort, alleviate postpartum uterine subinvolution, as well as the effects on myocardial and cerebral ischemic injuries. We hypothesized that these beneficial effects of motherwort may be related to angiogenesis. To test this hypothesis, we investigated the angiogenic effects of motherwort total alkaloids and essential oil, as well as their respective primary components, on zebrafish embryos. Motherwort total alkaloids significantly increased angiogenesis in transgenic Tg (flk1: EGFP) zebrafish embryos treated with sunitinib, as did stachydrine, the most abundant alkaloid produced by motherwort. Unexpectedly, motherwort essential oil was toxic to zebrafish embryos. Our results indicated, for the first time, that motherwort alkaloids were potent angiogenic agents, while even low concentrations of motherwort essential oil were toxic. As angiogenesis is a critical aspect of postpartum recovery, our results provide evidence for traditional application of motherwort water decoction and its Chinese patent medicines (e.g. motherwort injection) to promote postpartum recovery.

Graphene is a promising carbon nanomaterial, and multilayer graphene are more interesting than the monolayer one. The dispersion of multilayer graphene at terahertz (THz) leads to difficulties in transient electromagnetic simulation, e.g. the time domain integral equation (TDIE) method. This paper aims to achieve accurate fitting of multilayer graphene dispersive surface conductivity/impedance over ultra wideband THz frequencies. Graphene surface conductivity/impedance at THz is calculated by the Kubo formula. Thereafter, the surface conductivity and impedance is approximated by vector fitting method with expansions of several pairs of poles and residues. Numerical results are provided to validate the proposed method. Multilayer graphene time domain surface impedance which is used in the impedance boundary condition (IBC) for TDIE can be obtained readily by the inverse Fourier transform of its frequency domain counterpart.

LiNi0.5Mn0.5O2 suffers from surface structure instability and capacity degradation upon cycling, and single doping or coating cannot effectively solve the problem. In this work, the Sb-modified LiNi0.5Mn0.5O2 is successfully prepared by solid-state reaction process at high temperature, which simultaneously realizes Sb doping and Sb2O3 coating. Electrochemical experiments show that the Sb-modified LiNi0.5Mn0.5O2 material has enhanced electrochemical performance. The capacity retention of the Sb-modified LiNi0.5Mn0.5O2 material is 81.00% at 1.0 C after 250 cycles, while it is 59.08% for the bare sample, and performs 105.7 mAh g−1 at 5 C compared to 76.6 mAh g−1 for the bare sample. Therefore, Sb doping and Sb2O3 coating collaboration are beneficial to enhance electrochemical performance. This effective design strategy can be used to improve the electrochemical performance of other layered cathode materials.

In this work, SiO2@PDA nanoparticles obtained by in-situ coating polydopamine (PDA) on the surface of spherical SiO2 nanoparticles were adopted to prepare the polyvinylidene fluoride (PVDF) composite films via thermally-induced phase separation (TIPS) method with diphenyl carbonate (DPC) as the diluent. PDA was proved to cover evenly on the surface of SiO2 nanoparticles, which was favorable to the dispersion of hydrophilic nanoparticles in the matrix. Effect of the presence of SiO2@PDA nanoparticles on crystallization behavior, thermal stability, mechanical properties and hydrophilicity of the composite films was intensively investigated. Heterogeneous nucleating effect on the crystallization of PVDF coupled with elevated crystallinity was found upon the incorporation of SiO2@PDA without altering the crystal form of PVDF. The rigidity, tensile strength as well as thermal stability of the composite films containing SiO2@PDA were significantly improved in comparison to both neat film and those containing unmodified nanoparticles. In addition, the hydrophilicity of PVDF composite films’ surface was remarkably enhanced with an increasing SiO2@PDA content, which helped to reduce the protein adsorption of the composite films considerably. The present study would supply an insight into the fabrication of PVDF composite films with desirable performance and capabilities.

For the preparation of high-performance thermoset-based electromagnetic interference (EMI) shielding materials at low filler loading, a simple and practical method is still absent. Herein, the Epoxy/Polyether sulfone/Multi-walled Carbon Nanotubes (EP/PES/MWCNT) composites were prepared by ultrasonic treatment and dichloromethane-assisted dispersion. The selective localization of MWCNTs in EP phase prevented the interruption of phase continuity due to the increase of interfacial tension in the early stage of reaction-induced phase separation¸ resulting in co-continuous structure in the cured EP/PES (~80w/20w) blends. Therefore, reliable mechanical properties and satisfactory EMI shielding performance can be obtained at low MWCNT loading. The EP/PES23/MWCNT2.9 delivered the tensile strength of 69.7 MPa and the average EMI SE of 23.0 dB, and which can be further improved by increasing the MWCNT content. This work is expected to provide more approaches for the preparation of high-performance thermosetting EMI shielding materials.

Currently, the division of encounter situations and collision avoidance decisions both depend on the individual subjective judgment of officers under conditions of extraordinary complexity and randomness. Ambiguities and contradictions are present among the existing quantifications of azimuth division from the International Regulations for Preventing Collisions at Sea (COLREGS), radar collision avoidance diagrams, and expert questionnaire results. At present, there is no unified and practical division model for the variety of azimuth divisions encountered by ships. With the development of intelligent ship technology, the realization of maritime autonomous surface ships is possible. However, more obscure problems must be accurately defined. Moreover, the requirements for an accurate division of the ship encounter situation in maritime accident analysis are becoming more intense. Additional requirements have been imposed on the division of azimuth, and ship encounters have been quantified into multiple features for machine learning. In this study, automatic identification system data near Zhoushan Port were used to reproduce the relative motion process of ships, and extract the meeting position of the ship and the corresponding actual avoidance behavior. By combining the requirements for the light range in COLREGS and support vector classification to supervise and learn the actual meeting data, a map of the ship encounter azimuth division was constructed. The map can serve as an accurate numerical basis for the division of marine encounter situations, maritime accident responsibility division, and intelligent ship collision avoidance decisions.

Solution blending was used in this work to prepare graphene platelets (GNPs) modified recycled polyethylene terephthalate (RPET) composites in an attempt to disclose the presence of a filler network structure in the composites. The incorporation of GNP decreased the activation energy and produced nucleating effect on the crystallization of PET without altering the crystal form. The existence of GNP was found to cause an obvious enhancement in complex viscosity and storage modulus of composites via dynamic rheological testing as well as dynamic mechanical thermal analysis (DMTA). The Agari model presented the most reasonable prediction of the thermal conductivity as a function of GNP loading among the thermal conduction models. A four-parameter model (FPM) of melt solidification kinetics coupled with an in-situ temperature measurement agreed fairly with the variation of thermal conductivity versus GNP content, suggesting the formation of a GNP network structure which was also documented by SEM observations on the microstructures of the composites.

We report here an efficient approach to enhance the performance of biosensing platform based on graphene or graphene derivate. Initially, graphene oxides (GO) nanosheets were reduced and surface functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced graphene oxides (PDRGO). The bioinspired surface was further used as a support to anchor active gold nanoparticles (AuNPs). The morphology and structure of the as-prepared AuNPs/PDRGO nanocomposite were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR). Electrochemical studies demonstrate that the as-prepared AuNPs/PDRGO hybrid materials possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH at low potential (0.1 V vs. SCE) with the fast response (15 s) and the broad linear range (5.0×10 −8 –4.2×10 −5 M). Thus, this AuNPs/PDRGO nanocomposite can be further used to fabricate a sensitive alcohol biosensor using alcohol dehydrogenase (ADH), by simply incorporating the specific enzyme within the composite matrix with the aid of chitosan (Chit).

A superhydrophobic conductive surface with maximum static water contact angle of 165° and sliding angle of less than 3° was fabricated by grafting the copolymers of α-methylstyrene and butylmethacrylate, named PAB, onto multiwalled carbon nanotubes (MWCNTs) using free radical polymerization. The structures and the morphologies of PAB and PAB grafted MWCNTs were examined by infrared, nuclear magnetic resonance and Raman spectrometer, transmission and scanning electron microscope. The effects of pH value and exposure time on the stability of the superhydrophobic surface were also investigated. It indicates that the obtained superhydrophobic conductive surfaces are promising materials for numerous potential applications fields, including aerospace, electronic, battery electrodes and microfluidic areas.

Metro platform is a narrow space, poor air quality inside. In order to reduce internal air pollution, this article created a new metro ventilation and air conditioning system. This system makes the subway be effective within the pollutants be excluded out of indoors, and energy saving. A new significant ventilation and air conditioning system was created, which compared to the original system, not only reduce air pollution but also save more energy.

As evidence-based strategies to the clinical management of Barrett's esophagus (BE) are lacking, we have carried out a systematic review and meta-analysis of all published randomized controlled trials with the aim of evaluating the value of different approaches in the treatment of BE. Searches were conducted in the databases PUBMED, EMBASE, and Cochrane Library. Thirteen randomized clinical trials that fulfilled the inclusion criteria and addressed the clinical questions of this analysis were assessed in more detail. Based on our search, neither the pharmacological nor surgical therapies currently available for reflux appear to achieve complete regression of BE and the elimination of the cancer risk associated with it. In contrast, endoscopic ablative techniques are capable of achieving endoscopic and histological reversal of BE, with ablation by argon plasma coagulation (APC) appearing to be more effective than treatment with photodynamic therapy (PDT) [odds ratio (OR) 3.46, 95% confidence interval (CI) 1.67-7.81, P = 0.0008]. There was no statistically significant difference between APC and multipolar electrocoagulation (MPEC) in terms of the efficacy to achieve regression of BE (OR 2.01, 95% CI 0.77-5.23, P = 0.15). In conclusion, there have been only a limited number of randomized controlled trials that compare treatments for BE. The pharmacological therapy, antireflux surgery, and endoscopic ablative techniques are promising in terms of treating BE, but the studies carried out to date have had no adequate power to assess the effect of treatment on reducing and preventing progression to adenocarcinoma.

Prognostics and health management (PHM) is a highlight of current research in modern industrial equipment fields. Aiming at the requirement of verification of PHM system’s fault diagnosis capability, a fault injection device is designed and it consists of the digital control unit, fault injection unit, failure mode switching unit, channel switch unit, a status indication unit, data acquisition unit, communication unit and control software unit. The procedures of fault injection experiment are expounded in this chapter. Then a control computer system is applied to a fault injection experiment based on the probe-type fault injector, and the capabilities of fault diagnosis of PHM system are verified. Experiment results show that the probe-type fault injector can be effectively used to verify the PHM fault diagnosis capability of electronic systems and it is non-destructive and easy for operation.

The stability of amorphous Al 90 Fe 5 Ce 5 and Al 90 Ni 5 Ce 5 alloys and the stability of the structure corresponding to the prepeak during annealing process were investigated. Also the ageing effects of these alloys were investigated. Both the amorphous Al 90 Fe 5 Ce 5 and Al 90 Ni 5 Ce 5 alloys crystallize by two stages. The crystallization onset temperature for amorphous Al 90 Fe 5 Ce 5 alloys is much higher than that of the amorphous Al 90 Ni 5 Ce 5 alloys. The structure corresponding to the prepeak for amorphous Al 90 Fe 5 Ce 5 alloys is stable. However, it is not stable for amorphous Al 90 Ni 5 Ce 5 alloys, even decomposes at room temperature. By ageing effects, fcc Al is easily precipitated from amorphous matrix for the amorphous Al 90 Ni 5 Ce 5 alloys, whereas the amorphous Al 90 Fe 5 Ce 5 alloys is stable at room temperature. The stability of the structure corresponding to the prepeak strongly relates to the stability of the amorphous alloys.

X-ray diffraction (XRD) and differential scanning calorimetry were used to investigate the crystallization process of amorphous Al90TMxCe10−x alloys. Ageing effects were also examined by means of XRD. The structure corresponding to the prepeak for amorphous Al90Fe5Ce5 alloys is more stable than the amorphous matrix. However, amorphous Al90Ni5Ce5 alloys are not stable during the first crystallization stage, and even decompose at room temperature. The crystallization onset temperature for amorphous Al–Fe–Ce alloys is much higher than that for amorphous Al–Ni–Ce alloys. This is probably caused by the different stability of the structure corresponding to the prepeak. The crystallization onset temperature increases as the Ce/Ni ratio increases in amorphous Al90NixCe10−x alloys. However, the crystallization onset temperature decreases as the Ce/Fe ratio increases in amorphous Al90FexCe10−x alloys. A better atomic packing results as the Ce content increases due to size mismatch in Al–Ni–Ce systems and as the Fe content increases due to the increasing size of structural units in Al–Fe–Ce systems.

Miniaturization of optical-fiber chemical sensors has been achieved by near-field optics and photochemical synthesis. We have generalized this novel nanofabrication technique by using polymers doped with fluorescent dye or fluorescent dextran through photopolymerization. These doped polymers have been successfully used in chemical-sensor fabrication. The new methodologies make it possible to miniaturize further optical-fiber sensors with multiple chemical sensitivities by a multiple-step nanofabrication process.

Optical and excitonic nanoprobes have been fabricated using several novel techniques. These include micropipette tips and fiber-optic tips with polymeric or crystalline luminescent materials. The most important molecular technology we have developed is the near-field photo-nanofabrication, by which we have made subwavelength light sources and submicrometer intracellular biochemical optical fiber sensors. Both passive and active (luminescent) light sources have been used in interfacial Kasha quenching effect studies, biochemical sensing and supertip development. We have also shown that active light sources give much better detection limits in luminescent studies. An enhancement of three orders of magnitude in detection limit is expected

Energy conservation and rational usage of energy is China's basic national policy. The present steam consumption and heat loss of its pipeline network in Tianjin airport economic development zone is recorded, then zonal steam distribution efficiency is calculated to be 37.56 % by the steam consumption data, and zonal heat loss is in inverse proportion to steam distribution efficiency with factor of 8.312×104 kW, that is, in direct proportion to steam produce, steam enthalpy difference, inverse proportion to steam consumption with factor of 83.12 kW by the steam distribution efficiency, offering reasons to optimize steam pipeline network operation, and cover steam requirement with minimal energy consumption.

With rapid development of city rail transit, a greater degree of reduced energy consumption for rail transportation has been our key issues. In this paper, adjustable ventilation platform screen door was combined the platform screen door and security door systems together. All advantages of the both systems have been used. In different regions different forms of air conditioning systems were used to fully exploit the seasonal advantage of systems. Then more energy was saved. According to the simulation results, the ventilation and air conditioning systems in different climatic regions can meet regulatory requirements, save more energy.

Optical fiber sensors have several advantages over electrical-based sensors in many applications in chemistry and biology, but not with respect to minaturization and response time. Here the authors describe a near-field optical technique that enables the development of submicron-sized optical fiber sensors. The technology is based on nanofabricated optical fiber tips and near-field photoinitiated polymerization. Multimode or single-mode optical fibers are drawn into submicron optical fiber tips and then coated with aluminum to form submicron optical fiber light sources. Submicron pH sensors, as an example for small sensors, have been prepared by incorporating fluoresceinamine into an acrylamide-methylenebis(acrylamide) copolymer that is attached covalently to a silanized fiber tip surface by photoinitiated polymerization. The sensors have demonstrated their spatial resolving abilities in measuring the pH of buffer solutions inside micron-size holes in a polycarbonate membrane. These submicron pH sensors have millisecond response times due to their extremely small sizes. 20 refs., 6 figs.

Celiac disease (CD) is a type of intestinal malabsorption syndrome, in which the patients are intolerant to the gliadin in dietary gluten, resulting in chronic diarrhea and secondary malnutrition. The disease is common in Europe and the United States, but only sporadic reports are found in East Asia including China. Is CD really rare in China? We examined 62 patients by capsule endoscopy for chronic diarrhea from June 2003 to March 2008. Four patients with chronic diarrhea and weight loss were diagnosed to have CD. Under the capsule endoscopy, we observed that the villi of the proximal small bowel became short, and that the mucous membrane became atrophied in these four patients. Duodenal biopsies were performed during gastroscopy and the pathological changes of mucosa were confirmed to be Marsh 3 stage of CD. A gluten free diet significantly improved the conditions of the four patients. We suspect that in China, especially in the northern area where wheat is the main food, CD might not be uncommon, and its under-diagnosis could be caused by its clinical manifestations that could be easily covered by the symptoms from other clinical situations, particularly when it came to subclinical patients without obvious symptom or to patients with extraintestinal symptoms as the initial manifestations.

Time sequencing of laser excitation can control the microscopic patterns of molecular excitations (excitons) in nanometer scale molecular ensembles. This is demonstrated for isolated guest chains in polymer blends (P1VN/PMMA) and for molecular clusters in molecularly doped polymers (naphthalene/PMMA). The subwavelength exciton patterns are monitored via time resolved luminescence and fusion kinetics. The interpretation is aided by computer simulations

Near-field optics has been applied in the nanofabrication of subwavelength optical fiber chemical and biological sensors and their operation in chemical and biological analysis. A thousandfold miniaturization of immobilized optical fiber sensors has been achieved by a near- field photo-nanofabrication technique, which is based on nanofabricated optical fiber tips and near-field photopolymerization. This technique has been further developed by multistep near- field nanofabrication and multidye probe fabrication. Multistep nanofabrication can further miniaturize optical fiber sensors, while multidye fabrication results in multifunctional optic and excitonic probes with extremely small size. These probes emit multiwavelength photons or produce excitons of different energy levels, and may have multiple chemical or biological sensitivities. The nondestructive submicrometer sensor has demonstrated its ability to carry out static and dynamic determinations of pH in intact rat conceptuses of varying gestational ages. The ability of the sensors to measure pH changes, in real time, in the intact rat conceptus, demonstrates their potential applications for dynamic analysis in multicellular organisms and single cells. The near-field interaction of photons with matter is discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A thousandfold miniaturization of immobilized optical fiber sensors has been achieved by a near-field optical technique. This technology is based on nanofabricated optical fiber tips and near-field photoinitiated polymerization. Submicrometer pH sensors have been prepared by attaching a copolymer covalently to a silanized fiber tip surface. The sensors have demonstrated their high spatial resolving ability, excellent detection limit (zeptomoles), very fast response time (milliseconds) and good stability. The potential applications include concentration profile measurements of cytoplasms, the monitoring of fast chemical and biological reactions and other microscopic operations.

Subwavelength optical probes have been fabricated with micropipettes and nanofabricated optical fiber tips. A new near-field nanotechnology, photo-nanofabrication, has been developed, leading to a thousandfold miniaturization of immobilized Fiber Optical Chemical Sensors and to a billionfold decrease in necessary sample volume. Submicrometer pH sensors have been prepared by attaching a copolymer covalently to an activated nanofabricated fiber tip surface via near-field photo-polymerization. The sensors have demonstrated their excellent detection limit (zeptomoles) and fast response time (milliseconds). Applications of these subwavelength optical probes also include scanning tips, exciton probes and nanospectroscopy. Biological single cell analysis, supertip energy transfer, interfacial Kasha effect and near-field scanning spectroscopy illustrate our progress.

A thousandfold miniaturization of immobilized optical fiber sensors, a millionfold or more sample reduction, and at least a hundredfold shorter response time, all simultaneously, were achieved by combining nanofabricated optical fiber tips with near-field photopolymerization. Specifically, pH optical fiber sensors were prepared with internal calibration, making use of the differences in both fluorescence and absorption of the acidic and basic dye species. The submicrometer sensors have excellent detection limits, as well as photostability, reversibility, and millisecond response times. Successful applications include intracellular and intraembryonic measurements. Potential applications include spatially and temporally resolved chemical analysis and kinetics inside single biological cells and their substructures.