Showing papers by "Xiao Dong Chen published in 2013"

Observation of a charged charmoniumlike structure in e+ e- → (D* D*)± π∓ at √s = 4.26 GeV.

Abstract: We study the process e(+)e(-) -> pi(+)pi(-) J/psi at a center-of-mass energy of 4.260 GeV using a 525 pb(-1) data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9 +/- 1.9 +/- 3.7) pb, consistent with the production of the Y(4260). We observe a structure at around 3.9 GeV/c(2) in the pi(+/-) J/psi mass spectrum, which we refer to as the Z(c)(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the pi(+/-) J/psi invariant mass spectrum, neglecting interference, results in a mass of (3899.0 +/- 3.6 +/- 4.9) MeV/c(2) and a width of (46 +/- 10 +/- 20) MeV. Its production ratio is measured to be R = (sigma(e(+)e(-) -> pi(+/-) Z(c)(3900)(-/+) -> pi(+)pi(-) J/psi)/sigma(e(+)e(-) -> pi(+)pi(-) J/psi)) = (21.5 +/- 3.3 +/- 7.5)%. In all measurements the first errors are statistical and the second are systematic.

Pattern-Reconfigurable Planar Circular Ultra-Wideband Monopole Antenna

Abstract: A novel pattern-reconfigurable compact planar ultra-wideband monopole antenna is presented. By the incorporation of four p-i-n diode switches and two parasitic elements, the antenna's radiation patterns can be shaped to concentrate energy in specific directions while minimising the gain in other unwanted directions without significantly affecting the impedance bandwidth of the antenna. A fully functional prototype has been developed and tested. The measured results of the return loss, radiation patterns, and realised gain verify the effectiveness of the proposed antenna configuration. The antenna switches its radiation patterns between an omni-directional mode and two directional modes with opposite directions in the operating range from 3 to 6 GHz. The proposed antenna could be a suitable candidate for advanced and smart radio applications such as cognitive radio (CR) as it can enhance the radio front-end flexibility and performance by adding the benefits of pattern diversity, specifically in multipath environments.

Effects of Spray Drying and Freeze Drying on the Properties of Protein Isolate from Rice Dreg Protein

Abstract: This work was done to investigate the effects of different drying methods in the preparation of rice protein isolates (RPIs), as the understanding could provide useful information regarding applications of plant proteins in the food industry. RPI from rice dreg protein, a cheap by-product from the production of rice syrups, was extracted using an alkali solution along with isoelectric precipitation, and subsequently dried by freeze drying (FD-RPI) or spray drying (SD-RPI). The differences in biochemical, physical, and structural characteristics were observed for the dried proteins. SD-RPI had higher protein solubility and emulsifying activity at the pH values between 5 and 11, with higher foaming capacities (127.08 ± 2.25 % compared to 118.83 ± 2.71 %) than FD-RPI. However, FD-RPI had larger mean diameter (2,114.2 ± 79.6 nm compared to 490.4 ± 44.8 nm of SD-RPI), higher water/oil holding capacity (p < 0.05), and thermal stability. In addition, FD-RPI contained more β-turn structures (43.04 % compared to 25.81 %), and less β-sheet and random coils than SD-RPI, indicating that the more compact and ordered conformations of FD-RPI might be related to their physicochemical and functional properties. The choice of drying method could significantly influence physicochemical and conformational properties of RPIs, consequently determining their specific functional properties. The understanding of drying effects on their properties could assist in selecting the appropriate drying method to optimize the utilization of RPIs in the food industry.

A General “Surface‐Locking” Approach toward Fast Assembly and Processing of Large‐Sized, Ordered, Mesoporous Carbon Microspheres

Abstract: Drying to meet you: Using microfluidic jet spray drying technology in conjunction with the evaporation-induced self-assembly strategy gives fast assembly (2 s) of mesoporous carbon microspheres. The key feature of the drying is the formation of a rigid silica crust which locks the particle size and shape.

A Critical Review of Basic Crystallography to Salt Crystallization Fouling in Heat Exchangers

Abstract: Fouling formation on heat exchanger surfaces due to crystallization of inverse solubility salts is one of the fundamental problems in process industries. Despite numerous studies carried out in recent years, comprehensive understanding of crystallization fouling mechanism remains a challenge to chemical engineers. In this review, we first focus on the basic crystallography during deposition of calcium salts, paying attention to crystal structures and crystal forms, as well as nucleation and the subsequent crystal growth process. We then endeavor to relate a number of factors to fouling rate, which may be classified into three categories: solution composition, operating parameters, and heat exchanger surface characteristics. Each aspect is discussed from the crystallization viewpoint (science) and in terms of possible industrial applications (practice). Combining the basic knowledge of crystallography with the information from experimental investigations, several fouling mitigation methods have also been described that may reduce fouling. It is hoped that some of the ideas discussed here will provide possible economic and environmental benefits. Finally, we also try to throw some light on the future direction for research.

Determination of the number of ψ(3686) events at BESIII

Abstract: The number of ψ' events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×(1.00±0.81%)×106. The error is systematic dominant; the statistical error is negligible.

Stacked-Patch Dual-Polarized Antenna for Triple-Band Handheld Terminals

Abstract: In this letter, a novel design of a stacked-patch triple-band antenna in both circular and linear polarizations that can be used on a handheld terminal for surveying and geo-informatics applications is presented. The inculcation of corner truncation and I-slot in both the lower and middle patches has achieved better impedance bandwidth and axial ratio at GPS L1, L2, and GSM 1800 resonant frequency bands. A prototype of the proposed design is fabricated, and its performance is verified in measurement.

Modelling Drying Processes: A Reaction Engineering Approach

Abstract: This comprehensive summary of the state of the art and the ideas behind the reaction engineering approach (REA) to drying processes is an ideal resource for researchers, academics and industry practitioners. Starting with the formulation, modelling and applications of the lumped-REA, it goes on to detail the use of the REA to describe local evaporation and condensation, and its coupling with equations of conservation of heat and mass transfer, called the spatial-REA, to model non-equilibrium multiphase drying. Finally, it summarises other established drying models, discussing their features, limitations and comparisons with the REA. Application examples featured throughout help fine-tune the models and implement them for process design and the evaluation of existing drying processes and product quality during drying. Further uses of the principles of REA are demonstrated, including computational fluid dynamics-based modelling, and further expanded to model other simultaneous heat and mass transfer processes.

Imidazolium‐Functionalized SiO2 Nanoparticle Doped Proton Conducting Membranes for Anhydrous Proton Exchange Membrane Applications

Abstract: Imidazolium surface functionalized SiO2 (Im-SiO2) nanoparticle doped proton conducting membranes were prepared for anhydrous proton exchange membrane applications. The hybrid membranes were synthesized via in situ cross-linking of a mixture containing polymerizable oil (styrene, acrylonitrile, and divinylbenzene), protic ionic liquids (PILs), and 1-methyl-3-[(triethoxysilyl)propyl] imidazolium chloride surface functionalized silica nanoparticles. The resultant hybrid membranes show proton conductivity up to the order of 10–2 S cm–1 at 160 °C, which is higher that of the plain membrane (10–3 S cm–1 at 160 °C). In addition, incorporation of Im-SiO2 nanoparticles could effectively prevent the release of PIL component from the composite membranes.

Spatial reaction engineering approach as an alternative for nonequilibrium multiphase mass‐transfer model for drying of food and biological materials

Abstract: Drying is a complex process which involves simultaneous heat and mass transfer. Complicated structure and heterogeneity of food and biological materials add to the complexity of drying. Drying models are important for improving dryer design and for evaluating dryer performance. The lumped reaction engineering approach (L-REA) has been shown to be an accurate and robust alternative for cost-effective simulations of challenging drying systems. However, more insightful physics has to be shown spatially. In this study, the REA is coupled with the standard mechanistic drying models to yield the spatial-REA (S-REA) as nonequilibrium multiphase mass-transfer model. The S-REA consists of a system of equations of conservation with the REA representing the local evaporation and wetting rate. Results of the modeling using the S-REA match well with the experimental data reported previously. This is the first comprehensive REA approach to model the profiles of water vapor concentration during drying of food and biological materials. This study indicates that the S-REA can be an accurate nonequilibrium multiphase mass-transfer model with appropriate account of the local evaporation rate. The overall REA concept is expected to contribute substantially for better and cost-effective representation of transport phenomena of drying process. © 2012 American Institute of Chemical Engineers AIChE J, 59: 55–67, 2013

Significant effect of Ca2+ on improving the heat resistance of lactic acid bacteria

Abstract: The heat resistance of lactic acid bacteria (LAB) has been extensively investigated due to its highly practical significance. Reconstituted skim milk (RSM) has been found to be one of the most effective protectant wall materials for microencapsulating microorganisms during convective drying, such as spray drying. In addition to proteins and carbohydrate, RSM is rich in calcium. It is not clear which component is critical in the RSM protection mechanism. This study investigated the independent effect of calcium. Ca2+ was added to lactose solution to examine its influence on the heat resistance of Lactobacillus rhamnosus ZY, Lactobacillus casei Zhang, Lactobacillus plantarum P8 and Streptococcus thermophilus ND03. The results showed that certain Ca2+ concentrations enhanced the heat resistance of the LAB strains to different extents, that is produced higher survival and shorter regrowth lag times of the bacterial cells. In some cases, the improvements were dramatic. More scientifically insightful and more intensive instrumental study of the Ca2+ behavior around and in the cells should be carried out in the near future. In the meantime, this work may lead to the development of more cost-effective wall materials with Ca2+ added as a prime factor.

Determination of the number of psi ' events at BESIII

Abstract: The number of psi' events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41x(1.00+/-0.81%)x10(6). The error is systematic dominant; the statistical error is negligible.

Venturing into In Vitro Physiological Upper GI System Focusing on the Motility Effect Provided by a Mechanised Rat Stomach Model

Abstract: It is desirable to possess an in vitro digestion track model that can mimic to the fullest possible extent what is going on in a targeted animal system. Presently, there is still a long way before such a system becomes a reality despite a few attempts having been made in recent years to realise such a ‘dream’. Here, the design and laboratory experiences on a newly constructed in vitro rat stomach system are reported. Fine rice starch particles (obtained from cooked rice) have been used as the model food fed into the model stomach. Since the focus was on the motility effect, the microbial effect is neglected. The effects of motility rate and amplitudes of mechanical operation automated in the current rig have been focused upon and examined. The results are illustrative for a near-future development of a more effective construction of in vitro systems.

Application of acellular dermal xenografts in full-thickness skin burns

Abstract: The aim of this study was to explore the clinical value of the porcine acellular dermal xenograft (ADX) in combination with autologous split-thickness skin and pure autologous split-thickness skin grafting applied in deep full-thickness burns and scar wounds. A total of 30 patients with deep burns were randomly divided into experimental and control groups following escharectomy. The patients were separately treated with porcine acellular dermal xenograft (ADX) in combination with autologous split-thickness skin and pure autologous split-thickness skin graft. The wound healing was observed routinely and the scores were evaluated using Vancouver scar scale at different times following transplant surgery. The samples of cograft regions and the control group (pure transplant split-thickness skin autograft) were observed using light microscopy and electron microscopy, and the follow-up results were recorded. No conspicuous rejections on the cograft wound surface were observed. Compared with the control group, the cograft wounds were smooth, presented no scar contracture and exhibited good skin elasticity and recovery of the joint function. The cografted skin combined well and displayed a clear and continuous basal membrane, as well as gradually combined skin structure, a mature stratum corneum, downward extended rete pegs, a mainly uniform dermal collagen fiber structure, regular alignment, and fewer blood capillaries. Clear desmosome cograft regions were identified among heckle cells, as well as a clear and continuous basal membrane. The cografted skin of the combined split-thickness autograft and the acellular heterologous (porcine) dermal matrix showed an improved shape and functional recovery compared with the pure split-thickness skin autograft. The combination of the meshed ADX and the split-thickness skin autograft applied in deep full-thickness burns and scar wounds may induce tissue regeneration via dermis aiming. This method also has superior shape and functional recovery, and has an extensive clinical application value.

Multiphase modeling of intermittent drying using the spatial reaction engineering approach (S-REA)

Abstract: Several schemes of energy minimization of drying process including intermittent drying have been attempted. Intermittent drying is conducted by applying different heat inputs in each drying period. An effective and physically meaningful drying model is useful for process design and product technology. The lumped reaction engineering approach (L-REA) has been shown previously to be accurate to model the intermittent drying In L-REA, the REA (reaction engineering approach) is used to describe the global drying rate. In this study, the REA is used to model the local evaporation/condensation rate and combined with the mechanistic drying models to yield the spatial reaction engineering approach (S-REA), a non-equilibrium multiphase drying model. The accuracy of the S-REA to model the intermittent drying under time-varying drying air temperature is evaluated here. In order to incorporate the effect of time-varying drying air temperature, the equilibrium activation energy and boundary condition of heat balance implement the corresponding drying settings in each drying period. The results of modeling using the S-REA match well with the experimental data. The S-REA can yield the spatial profiles of moisture content, concentration of water vapor, temperature and local evaporation/condensation rate so that better understanding of transport phenomena of intermittent drying can be obtained. It is argued here that the REA can describe the local evaporation rate under time-varying external conditions well. The S-REA is an effective non-equilibrium multiphase approach for modeling of intermittent drying process.

Conductivity and frequency dependent specific absorption rate

Abstract: Recently, a number of contradicting results have been reported regarding the electromagnetic (EM) energy absorption by highly conductive materials in a liquid phase. The argument rises from the fact that higher conductive media absorb more electromagnetic energy; this however would be constrained by the localized field values that are dictated by the dielectric variations, which may reduce the absorption rate. Using salted water as an example, a systematic investigation of the mechanisms of EM absorption in the presence of highly conductive materials is conducted in this work. A theoretical model is developed, which is supported by both numerical and experimental studies. The influence of salt concentration, dielectric properties, boundary conditions, and EM frequency on the specific absorption rate (SAR) is carefully examined. The results show that the presence of salt in water modifies the dielectric properties significantly in the RF range, while the effect is less prominent in the microwave range. The SAR is highly dependent on the conductivity and frequency, as well as the employed instrument that dictates the surrounding boundary conditions. To suit different applications, the SAR can be optimized by proper consideration of the concentration of high conductivity material, operating frequency, and instruments.

Observation of a structure at 1.84 GeV/c(2) in the 3(pi(+)pi(-)) mass spectrum in J/psi -> gamma 3(pi(+) pi(-)) decays

Abstract: With a sample of 225.3 x 10(6) J/psi events taken with the BESIII detector, the decay J/psi -> gamma 3(pi(+) pi(-)) is analyzed. A structure at 1.84 GeV/c(2) is observed in the 3(pi(+) pi(-)) invariant mass spectrum with a statistical significance of 7.6 sigma. The mass and width are measured to be M = 1842.2 +/- 4.2(-2.6)(+7.1) MeV/c(2) and Gamma = 83 +/- 14 +/- 11 MeV. The product branching fraction is determined to be B(J/psi -> gamma X(1840) x B(X(1840) -> 3(pi(+)pi(-))) = (2.44 +/- 0.36(-0.74)(+0.60)) x 10(-5). No eta' signals are observed in the 3(pi(+) pi(-)) invariant mass spectrum, and the upper limit of the branching fraction for the decay eta' -> 3(pi(+) pi(-)) is set to be 3.1 x 10(-5) at a 90% confidence level.

Study of J/psi -> omega p(p)over-bar at BESIII

Abstract: The decay J/psi -> omega p (p) over bar has been studied, using 225.3 X 10(6) J/psi events accumulated at BESIII. No significant enhancement near the p (p) over bar invariant-mass threshold [denoted as X(p (p) over bar)] is observed. The upper limit of the branching fraction B(J/psi -> omega X(p (p) over bar) -> omega p (p) over bar is determined to be 3.9 X 10(-6) at the 95% confidence level. The branching fraction of J/psi -> omega p (p) over bar is measured to be B(J/psi -> omega p (p) over bar) = (9.0 +/- 0.2(stat) +/- 0. 9(syst) X 10(-4).

Hyperbaric oxygen therapy provides neuroprotection following spinal cord injury in a rat model.

Abstract: Objective: To investigate the effect of hyperbaric oxygen therapy (HBOT) on the iNOS mRNA-iNOS-NO signaling pathway and neurofunction protected in a rat spinal cord injury model. Methods: A total of 36 Sprague-Dawley rats were randomly divided into 3 groups: control group (n=12), SCI group (n=12) and SCI + HBOT group (n=12). SCI + HBOT group In the SCI group and SCI + HBOT groups, SCI was performed on rats. In the SCI + HBOT group, rats with SCI underwent HBO treatment 30 min after SCI for 24 sessions. After HBO therapy, measurement of motor evoked potential (MEP), Basso, Beattie, Bresnahan (BBB) scoring and pathological examination were done. RT-PCR and immunohistochemistry were employed to detect the mRNA and protein expression of iNOS, respectively. Diazo colorimetry was performed to detect the serum NO content. Results: The mRNA and protein expression of iNOS in the spinal cord and the serum NO content were markedly increased in the SCI group as compared to the control group (P<0.05). However, the mRNA and protein expression of iNOS and the serum NO content were dramatically reduced in the SCI + HBOT group as compared to the SCI group (P<0.05). Conclusion: HBO therapy can promote the neuroprotection following SCI, which may be related to the effect of HBO on the iNOS mRNA-iNOS-NO signaling pathway.

Comparative physicochemical analysis of suspended and immobilized cultivation of Chlorella sp

Abstract: BACKGROUND: Immobilized cultivation of microorganisms is gaining interest in the microalgae industry. In this study, a novel microalgae polymeric carrier, sodium cellulose sulphate/poly-dimethyl-diallyl-ammonium chloride (NaCS-PDMDAAC) capsule system, was employed to immobilize Chlorella sp. Microalgae cultivation was performed under immobilized and suspended conditions, and the resulting cells were characterized biochemically and physically. RESULTS: Experimental results indicated that microalgae cells cultivated under NaCS-PDMDAAC immobilized conditions have a robust morphology, a smaller average cell size of 2.92 µm and a higher Zeta potential of − 17.10 mV than the suspended cells with a cell size of 6.81 µm and Zeta potential of − 32.90 mV. The immobilized microalgae cells displayed a total lipid content of 14.85%, and a chlorophyll content of 3.36%, slightly higher than those obtained from the suspended cells. CONCLUSION: These differences are critical to further explore the impact of immobilized microalgae cultivation systems for specific biotechnological applications. © 2012 Society of Chemical Industry

Modeling Drying Processes: Reaction engineering approach I

Abstract: Description: This comprehensive summary of the state of the art and the ideas behind the reaction engineering approach (REA) to drying processes is an ideal resource for researchers, academics and industry practitioners. Starting with the formulation, modelling and applications of the lumped-REA, it goes on to detail the use of the REA to describe local evaporation and condensation, and its coupling with equations of conservation of heat and mass transfer, called the spatial-REA, to model non-equilibrium multiphase drying. Finally, it summarises other established drying models, discussing their features, limitations and comparisons with the REA. Application examples featured throughout help fine-tune the models and implement them for process design and the evaluation of existing drying processes and product quality during drying. Further uses of the principles of REA are demonstrated, including computational fluid dynamics-based modelling, and further expanded to model other simultaneous heat and mass transfer processes.