The Experts below are selected from a list of 193818 Experts worldwide ranked by ideXlab platform

Nicholas A Peppas - One of the best experts on this subject based on the ideXlab platform.

  • mechanisms of solute and drug transport in relaxing swellable hydrophilic glassy polymers
    Polymer, 1999
    Co-Authors: Christopher S Brazel, Nicholas A Peppas
    Abstract:

    Water and solute or drug transport in crosslinked polymeric materials was investigated to determine the effects of polymer morphology, composition and solute properties on transport behavior. Two crosslinked polymer systems, poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) and poly(vinyl alcohol) (PVA), were used in water transport and solute release experiments. Structural parameters of the polymers investigated in this work included the initial polymer molecular weight, the nominal crosslinking ratio, and the copolymer composition. Swelling rates, water diffusion coefficients and the diffusional Deborah Number, De, were used to characterize the water uptake process. Swelling rates correlated well with the polymer network mesh sizes; the slowest rate of water uptake was observed in P(HEMA-co-MMA) samples containing large quantities of methyl methacrylate. Initial crosslinking ratios had a sizable effect on water uptake in crosslinked PVA samples but not in the P(HEMA-co-MMA) polymers. Drug release rates, drug diffusion coefficients and the swelling Interface Number, Sw, were used to characterize solute transport. Release experiments were conducted using eight solutes: theophylline, triamterene, oxprenolol HCl, buflomedil HCl, vitamin B12, dextran, inulin and myoglobin. Release rates decreased with increasing solute molecular weight. A molecular weight cut-off, beyond which drug release was greatly hindered by the hydrogel mesh size, was established for each polymer tested.

  • dimensionless analysis of swelling of hydrophilic glassy polymers with subsequent drug release from relaxing structures
    Biomaterials, 1999
    Co-Authors: Christopher S Brazel, Nicholas A Peppas
    Abstract:

    Two dimensionless parameters, the diffusional Deborah Number, De, and the swelling Interface Number, Sw, were used as indicators of solvent and solute transport behavior in swellable hydrogel systems. Polymer relaxation and concentration-dependent diffusion led to dynamically swelling polymers which displayed Fickian, Case II, or anomalous transport behavior. Experimental systems studied included crosslinked samples of poly(vinyl alcohol), designated PVA, and poly(2-hydroxyethyl methacrylate-co-methyl methacrylate), designated P(HEMA-co-MMA). Model solutes with molecular weights ranging from 200 to 17,000 were used to investigate release properties from these networks. Characteristic polymer relaxation times and swelling front velocities were determined experimentally. To gain an understanding of how polymer morphology and solute properties affected transport behavior, the calculated values of De and Sw were correlated to the diffusional exponent, n, used commonly to indicate the time dependence of sorption and release. The swelling Interface Number was found to correlate particularly with the transport kinetics, indicating anomalous and Case II solute transport when the Sw values were near 1.0.

Ming-hour Yang - One of the best experts on this subject based on the ideXlab platform.

  • Research Article Storage-Efficient 16-Bit Hybrid IP Traceback with Single Packet
    2016
    Co-Authors: Ming-hour Yang
    Abstract:

    which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Since adversaries may spoof their source IPs in the attacks, traceback schemes have been proposed to identify the attack source. However, some of these schemes ’ storage requirements increase with packet Numbers. Some even have false positives because they use an IP header’s fragment offset for marking. Thus, we propose a 16-bit single packet hybrid IP traceback scheme that combines packet marking and packet logging with high accuracy and low storage requirement. The size of our log tables can be bounded by route Numbers. We also set a threshold to determine whether an upstream Interface Number is stored in a log table or in a marking field, so as to balance the logging frequency and our computational loads. Because we store user Interface information on small-degree routers, compared with current single packet traceback schemes, ours can have the lowest storage requirements. Besides, our traceback achieves zero false positive/negative rates and guarantees reassembly of fragmented packets at the destination. 1

  • Storage-efficient 16-bit hybrid IP traceback with single packet
    Scientific World Journal, 2014
    Co-Authors: Ming-hour Yang
    Abstract:

    Since adversaries may spoof their source IPs in the attacks, traceback schemes have been proposed to identify the attack source. However, some of these schemes' storage requirements increase with packet Numbers. Some even have false positives because they use an IP header's fragment offset for marking. Thus, we propose a 16-bit single packet hybrid IP traceback scheme that combines packet marking and packet logging with high accuracy and low storage requirement. The size of our log tables can be bounded by route Numbers. We also set a threshold to determine whether an upstream Interface Number is stored in a log table or in a marking field, so as to balance the logging frequency and our computational loads. Because we store user Interface information on small-degree routers, compared with current single packet traceback schemes, ours can have the lowest storage requirements. Besides, our traceback achieves zero false positive/negative rates and guarantees reassembly of fragmented packets at the destination.

Christopher S Brazel - One of the best experts on this subject based on the ideXlab platform.

  • mechanisms of solute and drug transport in relaxing swellable hydrophilic glassy polymers
    Polymer, 1999
    Co-Authors: Christopher S Brazel, Nicholas A Peppas
    Abstract:

    Water and solute or drug transport in crosslinked polymeric materials was investigated to determine the effects of polymer morphology, composition and solute properties on transport behavior. Two crosslinked polymer systems, poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) and poly(vinyl alcohol) (PVA), were used in water transport and solute release experiments. Structural parameters of the polymers investigated in this work included the initial polymer molecular weight, the nominal crosslinking ratio, and the copolymer composition. Swelling rates, water diffusion coefficients and the diffusional Deborah Number, De, were used to characterize the water uptake process. Swelling rates correlated well with the polymer network mesh sizes; the slowest rate of water uptake was observed in P(HEMA-co-MMA) samples containing large quantities of methyl methacrylate. Initial crosslinking ratios had a sizable effect on water uptake in crosslinked PVA samples but not in the P(HEMA-co-MMA) polymers. Drug release rates, drug diffusion coefficients and the swelling Interface Number, Sw, were used to characterize solute transport. Release experiments were conducted using eight solutes: theophylline, triamterene, oxprenolol HCl, buflomedil HCl, vitamin B12, dextran, inulin and myoglobin. Release rates decreased with increasing solute molecular weight. A molecular weight cut-off, beyond which drug release was greatly hindered by the hydrogel mesh size, was established for each polymer tested.

  • dimensionless analysis of swelling of hydrophilic glassy polymers with subsequent drug release from relaxing structures
    Biomaterials, 1999
    Co-Authors: Christopher S Brazel, Nicholas A Peppas
    Abstract:

    Two dimensionless parameters, the diffusional Deborah Number, De, and the swelling Interface Number, Sw, were used as indicators of solvent and solute transport behavior in swellable hydrogel systems. Polymer relaxation and concentration-dependent diffusion led to dynamically swelling polymers which displayed Fickian, Case II, or anomalous transport behavior. Experimental systems studied included crosslinked samples of poly(vinyl alcohol), designated PVA, and poly(2-hydroxyethyl methacrylate-co-methyl methacrylate), designated P(HEMA-co-MMA). Model solutes with molecular weights ranging from 200 to 17,000 were used to investigate release properties from these networks. Characteristic polymer relaxation times and swelling front velocities were determined experimentally. To gain an understanding of how polymer morphology and solute properties affected transport behavior, the calculated values of De and Sw were correlated to the diffusional exponent, n, used commonly to indicate the time dependence of sorption and release. The swelling Interface Number was found to correlate particularly with the transport kinetics, indicating anomalous and Case II solute transport when the Sw values were near 1.0.

  • Mechanisms of solute and drug transport in relaxing, swellable, hydrophilic glassy polymers, Polymer 40
    1999
    Co-Authors: Christopher S Brazel
    Abstract:

    Water and solute or drug transport in crosslinked polymeric materials was investigated to determine the effects of polymer morphology, composition and solute properties on transport behavior. Two crosslinked polymer systems, poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) and poly(vinyl alcohol) (PVA), were used in water transport and solute release experiments. Structural parameters of the polymers investigated in this work included the initial polymer molecular weight, the nominal crosslinking ratio, and the copolymer composition. Swelling rates, water diffusion coefficients and the diffusional Deborah Number, De, were used to characterize the water uptake process. Swelling rates correlated well with the polymer network mesh sizes; the slowest rate of water uptake was observed in P(HEMA-co-MMA) samples containing large quantities of methyl methacrylate. Initial crosslinking ratios had a sizable effect on water uptake in crosslinked PVA samples but not in the P(HEMA-co-MMA) polymers. Drug release rates, drug diffusion coefficients and the swelling Interface Number, Sw, were used to characterize solute transport. Release experiments were conducted using eight solutes: theophylline, triamterene, oxprenolol HCl, buflomedil HCl, vitamin B 12, dextran, inulin and myoglobin. Release rates decreased with increasing solute molecular weight. A molecular weight cut-off, beyond which drug release was greatly hindered by the hydrogel mesh size, wa

Rajdeep Niyogi - One of the best experts on this subject based on the ideXlab platform.

  • Chapter 16 ROUTER AND Interface MARKING FOR NETWORK FORENSICS
    2015
    Co-Authors: Emmanuel Pilli, Ramesh Joshi, Rajdeep Niyogi
    Abstract:

    Abstract The primary aim of network forensics is to trace attackers and obtain evidence for possible prosecution. Many traceback techniques exist, but most of them focus on distributed denial of service (DDoS) attacks. This paper presents a novel traceback technique that deterministically marks the Interface Number and the address of the router from which each outgoing packet entered the network. An analysis against various traceback metrics demonstrates that the technique enhances network attack attribution

  • Router and Interface Marking for Network Forensics
    2011
    Co-Authors: Emmanuel Pilli, Ramesh Joshi, Rajdeep Niyogi
    Abstract:

    The primary aim of network forensics is to trace attackers and obtain evidence for possible prosecution. Many traceback techniques exist, but most of them focus on distributed denial of service (DDoS) attacks. This paper presents a novel traceback technique that deterministically marks the Interface Number and the address of the router from which each outgoing packet entered the network. An analysis against various traceback metrics demonstrates that the technique enhances network attack attribution.

Chuanxian Ding - One of the best experts on this subject based on the ideXlab platform.

  • smart hydrogels co switched by hydrogen bonds and π π stacking for continuously regulated controlled release system
    Advanced Functional Materials, 2010
    Co-Authors: Yingchun Zhu, Bo You, Donghui Zhao, Qichao Ruan, Yi Zeng, Chuanxian Ding
    Abstract:

    A series of hydrogels with continuously regulatable release behavior can be achieved by incorporating hydrogen bonding and π–π stacking co-switches in polymers. A poly(nitrophenyl methacrylate-co-methacrylic acid) hydrogel (NPMAAHG) for control over drug release is fabricated by copolymerizing 4-nitrophenyl methacrylate and methacrylic acid using ethylene glycol dimethacrylate as a crosslinker. The carboxylic acid groups and nitrylphenyl groups form hydrogen bonds and π–π stacking interactions, respectively, which act as switches to control the release of guest molecules from the polymers. As revealed by the simulated gastrointestinal tract drug release experiments, the as-synthesized NPMAAHG hydrogels can be regulated to release only 4.7% of drugs after 3 h in a simulated stomach and nearly 92.6% within 43 h in the whole digestive tract. The relation between the release kinetics and structures and the mechanism of the smart release control are analyzed in terms of diffusion exponent, swelling Interface Number, drug diffusion coefficient, and velocity of the swelling Interface in detail. The results reveal that the release of guest molecules from the hydrogels can be continuously regulated for systemic administration by controlling the ratio of the hydrophilic hydrogen bonds and the hydrophobic π–π stacking switches.