Conjunctival Lymphangiogenesis Was Associated with the Degree of Aggression in Substantial Recurrent Pterygia

Objective. To examine conjunctival lymphatic vessels and to analyze the relationship between lymphangiogenesis and aggressive recurrent pterygia. Methods. Tissues from 60 excised recurrent (including 19 of Grade 1, 28 of Grade 2, and 13 of Grade 3) pterygia were used in the study. Tissues from 9 nasal epibulbar conjunctivae segments were used as controls. Pterygium slices from each patient were immunostained with LYVE-1 monoclonal antibodies to identify lymphatic microvessels in order to calculate the lymphovascular area (LVA), the lymphatic microvessel density (LMD), and the lymphovascular luminal diameter (LVL). The relationship between lymphangiogenesis (LVA, LMD, and LVL) and pterygium aggression (width, extension, and area) was clarified. Results. Few LYVE-1 positive lymphatic vessels were found in the normal epibulbar conjunctiva segments. Lymphatic vessels were slightly increased in Grades 1 and 2 and were dramatically increased in Grade 3 recurrent pterygia. The LMD was correlated with the pterygium area in Grade 1 and 2 pterygia. In Grade 3, both LVA and LMD were significantly correlated with the pterygium area. Conclusions. Lymphangiogenesis was associated with the degree of aggression in recurrent pterygia, particularly in substantial Grade 3 recurrent pterygia

Paramagnetic behaviour of silver nanoparticles generated by decomposition of silver oxalate

Silver oxalate Ag2C2O4, was already proposed for soldering applications, due to the formation when it is decomposed by a heat treatment, of highly sinterable silver nanoparticles. When slowly decomposed at low temperature (125 °C), the oxalate leads however to silver nanoparticles isolated from each other. As soon as these nanoparticles are formed, the magnetic susceptibility at room temperature increases from -3.14 10-7 emu.Oe-1.g-1 (silver oxalate) up to -1.92 10-7 emu.Oe-1.g-1 (metallic silver). At the end of the oxalate decomposition, the conventional diamagnetic behaviour of bulk silver, is observed from room temperature to 80 K. A diamagnetic-paramagnetic transition is however revealed below 80 K leading at 2 K, to silver nanoparticles with a positive magnetic susceptibility. This original behaviour, compared to the one of bulk silver, can be ascribed to the nanometric size of the metallic particles

Application of GFAT as a Novel Selection Marker to Mediate Gene Expression

The enzyme glutamine: fructose-6-phosphate aminotransferase (GFAT), also known as glucosamine synthase (GlmS), catalyzes the formation of glucosamine-6-phosphate from fructose-6-phosphate and is the first and rate-limiting enzyme of the hexosamine biosynthetic pathway. For the first time, the GFAT gene was proven to possess a function as an effective selection marker for genetically modified (GM) microorganisms. This was shown by construction and analysis of two GFAT deficient strains, E. coli ΔglmS and S. pombe Δgfa1, and the ability of the GFAT encoding gene to mediate plasmid selection. The gfa1 gene of the fission yeast Schizosaccharomyces pombe was deleted by KanMX6-mediated gene disruption and the Cre-loxP marker removal system, and the glmS gene of Escherichia coli was deleted by using λ-Red mediated recombinase system. Both E. coli ΔglmS and S. pombe Δgfa1 could not grow normally in the media without addition of glucosamine. However, the deficiency was complemented by transforming the plasmids that expressed GFAT genes. The xylanase encoding gene, xynA2 from Thermomyces lanuginosus was successfully expressed and secreted by using GFAT as selection marker in S. pombe. Optimal glucosamine concentration for E. coli ΔglmS and S. pombe Δgfa1 growth was determined respectively. These findings provide an effective technique for the construction of GM bacteria without an antibiotic resistant marker, and the construction of GM yeasts to be applied to complex media

Cross-layer design for ad hoc and infrastructured next-generation wireless networks

Traditional communication systems are designed using a layered approach based on the open system interconnection (OSI) reference model. According to this design philosophy, each layer offers certain services to the higher layers, by shielding those layers from the details of how the services are implemented. Consequently, each layer optimizes its own goal and the design can hardly be optimal from an overall system point of view. Because of the increasing demand of wireless communication systems, it is more and more necessary for the system designers to implement more efficient protocols through a cross-layer approach. The nature of a cross-layer design is to provide an innovative insight into the vertical integration of different protocol layers with the ultimate goal of achieving efficient management of system resources. In this thesis, we present several cross-layer methodologies, primarily in the context of integrating the physical (PHY) and medium access control (MAC) layers, to more efficiently support adaptability and optimization in wireless networks. Our numerical and simulation results demonstrate that significant improvement in the system performance such as throughput, power-efficiency, average packet delay, and system stability can be achieved by our cross-layer approaches, compared with conventional schemes where integrated layer adaptation, design, and optimization are not used. Two types of wireless architectures are investigated: Wireless ad hoc networks and infrastructured wireless networks. For wireless ad hoc networks, we propose a cross-layer optimization framework to jointly design the scheduling and power control. Specifically, the transmitted power and constellation size are dynamically adapted based on the packet arrival, quality of service (QoS) requirements, power limits, and channel conditions. A key feature of the proposed method is that it facilitates a distributed implementation, which is desirable in wireless ad hoc networks. The performance of our proposed methodology is investigated for both cases of unicasting and multicasting. As for infrastructured wireless networks, we first propose a cross-layer adaptive resource allocation and scheduling approach for the downlink transmission of a multi-input multi-output (MIMO)/orthogonal frequency division multiplexing (OFDM) system. The proposed algorithm jointly implements the scheduling at the MAC layer and the subcarrier, bit and power allocation at the physical layer. We then investigate the uplink counterpart, which jointly designs a multi-packet reception (MPR)-based MAC protocol and adaptive resource allocation for a MIMO/OFDM system. Our algorithm provides interconnection and information exchange between the MAC and PHY layers through the use of a request-to-send (RTS)/clear-to-send (CTS) based multiple access mechanism, and an allocation problem is formulated to encapsulate both of the MAC and PHY issues. Finally, we extend our design by adopting a channel state information (CSI)-based random access in a wireless local area network (WLAN) system supporting MPR. In this algorithm, when the backoff time counter reduces to zero, each node selectively transmits according to a channel threshold which is determined by the network population, estimated CSI, as well as the MPR capability of the system. A throughput expression is also derived by taking transmission errors into consideration. The optimal channel threshold is also obtained to maximize the system throughput

Channel state adaptive random access for SDMA based wireless LANs

In this paper, we propose a channel state adaptive random access for a wireless local area network (WLAN) where multiple receive antennas are used for space division multiple access (SDMA). In contrast to conventional medium access control (MAC) protocols which were designed separately from the characteristics of the physical (PHY) layer, our proposed protocol takes advantages of multi-packet reception (MPR) capability of the system which takes into consideration the channel state information (CSI). Specifically, each node's transmission is dynamically controlled based on the network population, current channel condition, as well as the number of receive antennas. The average frame error rate and throughput expression are derived as functions of the transmission control. An optimal transmission policy is then obtained to achieve the maximum throughput. Numerical results show that our cross-layer approach significantly outperforms conventional schemes where CSI is not taken into consideration or MPR is not allowed. The tradeoff between the performance improvement and hardware cost is also illustrated

Effects of geochemical conditions, surface modification, and arsenic (As) loadings on As release from As-loaded nano zero-valent iron in simulated groundwater

Arsenic (As) released from As-loaded nano zero-valent iron (nZVI) after As(V) remediation could become an environmental hazard, thus deserving in-depth investigations. This study investigated As release from As-loaded nZVI under different geochemical conditions (i.e., pH, Ca2+, and humic acid (HA) concentrations), as well as the effects of nZVI surface modification (chitosan and polyaniline) and As loadings (low and high) on As release. Alkaline condition (pH = 9) and the presence of humic acid were found to enhance As release from all the types of nZVI samples. Ca2+ had no effect on As release for all the types of nZVI at both As loadings, except for chitosan- and polyaniline-modified nZVI at high As loading when Ca2+ concentrations increased up to 16 mg L−1. At low As loading, surface modification had a limited impact on As release from As-loaded nZVI. When As loading was high, a higher percentage of As was released from pristine nZVI than those from both the types of modified nZVI. This is because pristine nZVI either formed only monodentate complexes or had a higher ratio of As(III)/As(V). Under the same geochemical conditions, As released from all the types of As-loaded nZVI at high As loadings was lower than that at low As loadings. This is due to the formation of bidentate complexes with stronger bindings and lower ratios of As(III)/As(V) for high As loadings. These findings provide a fundamental understanding regarding the environmental behaviors of As-loaded nZVI under natural conditions and the risk associated with the release of As from As-loaded nZVI

pH and Redox Dual-Responsive Mesoporous Silica Nanoparticle as Nanovehicle for Improving Fungicidal Efficiency

Prochloraz (Pro) controlled-release nanoparticles (NPs) based on bimodal mesoporous silica (BMMs) with redox and pH dual responses were successfully prepared in this study. BMMs was modified by a silane coupling agent containing a disulfide bond, and β-cyclodextrin (β-CD) was grafted on the surface of the NPs through host–guest interaction. Pro was encapsulated into the pores of nanoparticles by physical adsorption. NPs had a spherical structure, and their average diameter was 546.4 ± 3.0 nm as measured by dynamic light scattering. The loading rate of Pro was 28.3%, and it achieved excellent pH/redox dual-responsive release performance under acidic conditions. Foliage adhesion tests on tomato leaves showed that the NPs had good adhesion properties compared to the commercial formulation. Owing to the protection of the nanocarrier, NPs became more stable under ultraviolet light and high temperature, which improves the efficient utilization of Pro. Biological activity tests showed that the NPs exhibited effective antifungal activity, and the benign biosafety of the nanocarrier was also observed through toxicology tests on cell viability and the growth of Escherichiacoli (E. coli). This work provides a promising approach to improving the efficient utilization of pesticides and reducing environmental pollution

A functional bimodal mesoporous silica nanoparticle with redox/cellulase dual-responsive gatekeepers for controlled release of fungicide

Abstract Integrating toxic fungicide into a functional stimuli-responsive nanosystem can effectively improve the fungus control specificity and reduce the effect on non-target organisms. We report here a redox and cellulase dual-responsive multifunctional nanoparticle based on bimodal mesoporous silica (BMMs) to deliver prochloraz (Pro) for the smart management of wilt disease (Pro-AC-SS-BMMs, known as P-ASB). The surface of the nanocarrier was modified with an aminosilane coupling agent, and Pro was encapsulated by physical adsorption using 2,2′-dithiodiacetic acid as a smart bridge and disulfide (SS) cross-linked aminocellulose (AC) as gatekeepers. P-ASB nanoparticles (NPs) had a spherical structure, and the size was 531.2 ± 4.9 nm. The loading rate of Pro was 28.5%, and the NPs possessed excellent redox/cellulase dual-responsive release characteristics in the presence of glutathione (GSH) and cellulase. The nanocarrier could effectively protect Pro against photodegradation and had better foliar wettability than the Pro technical. Fluorescence tracer results showed that the nanocarriers were taken up and activated by the mycelium. P-ASB NPs had better control efficacy against Rhizoctonia solani and had no significant toxicity to cells and bacteria. This study provides a new strategy for enhancing the environmental protection and promoting the development of green agriculture

Understanding the Relations between Surface Stress State and Microstructure Feature for Enhancing the Fatigue Performance of TC6 Titanium Alloy

Fatigue performance has always been an important factor affecting the application of titanium alloy. The service life of TC6 titanium alloy is easily reduced under a continuously alternating load. Therefore, there is an urgent need for a new method to improve fatigue performance. Laser shock peening (LSP) is a widely proposed method to enhance the fatigue performance. Here, through experiments and finite element simulations, it was found that LSP can prolong the fatigue life of TC6 by improving the surface stress state. In strengthening processes, the generation of residual stress was mainly attributed to the change of microstructure, which could be reflected by the statistical results of grain sizes. The content of grains with a size under 0.8 μm reached 78%, and the microhardness value of treated TC6 was 18.7% higher than that of an untreated sample. In addition, the surface residual compressive stress was increased to −600 MPa at the depth of 1500 μm from the surface. On this basis, the fatigue life was prolonged to 135%, and the ultimate fracture macroscopic was also changed. With the treatment of LSP, the fatigue performance of TC6 is highly promoted. The strengthening mechanism of LSP was established with the aim of revealing the relationship between microstructure and stress state for enhancing the fatigue performance in whatever shapes