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1.
Math Biosci Eng ; 17(6): 7221-7233, 2020 10 22.
Article in English | MEDLINE | ID: mdl-33378894

ABSTRACT

Dynamic computer forensics is a popular area in computer forensics that combines network intrusion technology with computer forensics technology. A novel dynamic computer forensics model is proposed based on an artificial immune system. Simulating the artificial immune mechanism, the definitions of self, non-self, and immunocyte in the network transactions are given. Then, detailed evolution processes for immature detectors, mature detectors, and memory detectors are given. Real-time network risk evaluation equations are constructed, which can compute the risk of each type of network attack. Finally, computer forensics is accomplished according to the real-time network risk. The immune cells dynamically capture the real-time computer system status of the invading antigen, including CPU utilization, memory utilization, network bandwidth utilization status, etc. Theoretical analysis and comparative experimental results demonstrate that the proposed model improves the real-time efficiency and performance with low technical requirements for technicians compared with existing models.


Subject(s)
Artificial Intelligence , Computer Systems , Algorithms , Computer Simulation , Computers , Memory
2.
J Biomater Sci Polym Ed ; 27(16): 1674-84, 2016 11.
Article in English | MEDLINE | ID: mdl-27539878

ABSTRACT

In this work, we investigate the enhanced mechanical properties of nano-hydroxyapatite/polyamide 66 (nHA/PA66) composites reinforced with multi-walled carbon nanotubes (MWCNTs) by means of the blending method. The MWCNTs-nHA/PA66 composites were characterized by various techniques, and the obtained results indicated that the MWCNTs were evenly distributed in the composite and that good interfacial bonding was formed between MWCNTs and PA66. The addition of MWCNTs improved the crystallinity of PA66, while it had little or no effect either on the composition or on the crystal structure of the composites. Moreover, the addition of MWCNTs in nHA/PA66 significantly improved the mechanical strength, and the tensile and compressive strengths attained maximum values of 90.3 and 126.8 MPa, respectively, with the addition of 0.1 wt% MWCNTs, whereas the bending strength attained a maximum value of 105.5 MPa with the addition of 0.05 wt% MWCNTs. Finally, L929 cells co-cultured with the MWCNTs-nHA/PA66 composite exhibited comparatively uninhibited cell growth, indicating that the addition of MWCNTs had negligible effect on the cytocompatibility of the original nHA/PA66 composite.


Subject(s)
Biocompatible Materials/chemistry , Biocompatible Materials/chemical synthesis , Durapatite/chemistry , Nanocomposites/chemistry , Nanotubes, Carbon/chemistry , Nylons/chemistry , Animals , Biocompatible Materials/toxicity , Cell Line , Chemistry Techniques, Synthetic , Materials Testing , Mice , Nanocomposites/toxicity
3.
Mater Sci Eng C Mater Biol Appl ; 63: 285-91, 2016 Jun.
Article in English | MEDLINE | ID: mdl-27040221

ABSTRACT

The combination of nano-hydroxyapatite (n-HA) and polypropylene carbonate (PPC) was used to make a composite materials by a coprecipitation method. The physical and chemical properties of the composite were tested. Scanning electron microscope (SEM) observation indicated that the biomimetic n-HA crystals were uniformly distributed in the polymer matrix. As the n-HA content increased in the composite, the fracture mechanism of the composites changes from gliding fracture to gliding and brittle fracture. Furthermore, the chemical interaction between inorganic n-HA and polypropylene carbonate was also investigated and discussed in detail. The hydrogen bonds might be formed between -OH/CO3(2-) of n-HA crystal and the ester group (-COO-) of PPC. The tensile strength of n-HA/PPC (40/60) was similar to that of the cancellous bone, and reached ca 58 MPa. The osteoblasts were cultured for up to 7 days, and then the adhesion and proliferation of osteoblasts were measured by Methyl thiazolyl tetrazolium (MTT) colorimetry assay and SEM. The cells proliferated, grew normally in fusiform shape and well attached. The in vitro test confirmed that the n-HA/PPC composites were biocompatible and showed undetectable negative effect on osteoblasts. In vivo implantation of the composite in New Zealand white rabbits was performed. It can stimulate the growth of a new bone, and at the same time the material begins to degrade. These results suggested that the composite may be suitable for the reparation or replacement of bone defects and possessed the potential for clinical applications.


Subject(s)
Biocompatible Materials/chemistry , Durapatite/chemistry , Polypropylenes/chemistry , Animals , Biocompatible Materials/pharmacology , Bone Substitutes/chemistry , Bone Substitutes/pharmacology , Cell Line , Cell Survival/drug effects , Femur/pathology , Humans , Microscopy, Electron, Scanning , Rabbits , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Tensile Strength , X-Ray Diffraction
4.
J Biomed Mater Res B Appl Biomater ; 100(1): 51-7, 2012 Jan.
Article in English | MEDLINE | ID: mdl-21953937

ABSTRACT

High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair.


Subject(s)
Bone and Bones , Chitosan/chemistry , Coated Materials, Biocompatible/chemistry , Durapatite/chemistry , Nanocomposites/chemistry , Nylons/chemistry , Tissue Engineering/methods , Tissue Scaffolds/chemistry , Bone Regeneration , Cell Line, Tumor , Humans , Materials Testing , Porosity
5.
J Biomed Mater Res B Appl Biomater ; 95(1): 36-46, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20665683

ABSTRACT

The purpose of this study is to explore and develop biodegradable scaffold for bone regeneration or tissue engineering with the capacity of controlled drug delivery. Ceftazidime as a model drug was encapsulated in ethyl cellulose (EC) microspheres, which were subsequently incorporated in a hydroxyapatite/polyurethane (HA/PU) composite scaffold to generate an antibiotic drug delivery system. HA/PU scaffolds had an interconnected pore network with an average porosity of about 83%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy. The drug-loaded EC microspheres were uniformly distributed in the HA/PU scaffold matrix and showed no significant effect on the pore structure of the scaffold. Incorporation of microspheres into scaffolds significantly reduced the initial burst release, and the system exhibited a sustained release of the model drug for up to 60 days. Moreover, the scaffold with drug-loaded microspheres was proved to be an effective drug delivery system with good cytocompatibility and antibacterial properties. The novel drug-loaded microsphere/scaffold composites developed in this study are promising to serve as vehicles for controlled drug delivery in bone regeneration or bone tissue engineering.


Subject(s)
Bone Regeneration/drug effects , Drug Delivery Systems/methods , Durapatite/therapeutic use , Polyurethanes/therapeutic use , Tissue Scaffolds/chemistry , Anti-Bacterial Agents/administration & dosage , Ceftazidime/administration & dosage , Cell Line , Cellulose/analogs & derivatives , Humans , Microspheres , Osteoblasts/cytology , Tissue Engineering/methods
6.
J Biomater Sci Polym Ed ; 21(12): 1619-36, 2010.
Article in English | MEDLINE | ID: mdl-20537245

ABSTRACT

Polymer nano-composite membranes, based on aliphatic biodegradable polyurethane (PU) elastomers and nano-hydroxyapatite (n-HA), were prepared by solvent casting and freeze-drying. The PU matrix was synthesized from 4,4'-dicyclohexylmethane diisocyanate (H(12) MDI), poly(ethylene glycol) (PEG), castor oil (CO) and 1,4-butandiol (BDO). The n-HA/PU membranes were characterized by SEM, XRD, IR, TG, mechanical test and in vitro biocompatibility. The results revealed that incorporation of 30 wt% n-HA into the PU matrix increased the tensile strength nearly by 186% and the elongation-at-break by 107% compared to pure PU. The addition of n-HA had the slight positive effect on the thermal stability of PU. Cell culture and MTT assays showed that the incorporation of n-HA into the PU matrix provided a favourable environment for initial cell adhesion, maintained cell viability and cell proliferation. These results suggested that the n-HA/PU composite membrane might be a prospective biodegradable guided bone regeneration (GBR) membrane for future applications.


Subject(s)
Chemical Phenomena , Durapatite/chemistry , Durapatite/pharmacology , Membranes, Artificial , Nanostructures/chemistry , Polyurethanes/chemistry , Bone Regeneration , Cell Adhesion/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Humans , Materials Testing , Mechanical Phenomena , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Spectroscopy, Fourier Transform Infrared , Thermogravimetry
7.
J Biomed Mater Res A ; 93(3): 1020-31, 2010 Jun 01.
Article in English | MEDLINE | ID: mdl-19743510

ABSTRACT

In this article gentamicin (GM) impregnated microspheres were used to extend the drug release time for the treatment of chronic osteomyelitis. The granules were prepared in solution and consisted of nanohydroxyapatite (nHA), chitosan (CS) and GM loaded ethyl cellulose (EC) microspheres. A rabbit model with chronic osteomyelitis was made by using staphylococcus aureus and morrhuate sodium and special inspection methods were used to test the curative effects of the granules, such as microbiological investigations, tissue, and X-ray observations. The granules were provided with excellent drug release properties, 49 days in vitro and 45 days in vivo, moreover, they showed almost no cytotoxic for fibroblast and osteoblast. The findings indicated that the GM-impregnated CS/nHA/EC microspheres granules showed outstanding curative effect. Generally, it can be concluded that the granules containing GM impregnated microspheres may be used effectively in the treatment of the chronic osteomyelitis.


Subject(s)
Cellulose/analogs & derivatives , Chitosan/pharmacology , Durapatite/pharmacology , Gentamicins/therapeutic use , Microspheres , Nanostructures/chemistry , Osteomyelitis/drug therapy , Animals , Cell Death/drug effects , Cell Survival/drug effects , Cellulose/pharmacology , Chronic Disease , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/metabolism , Gentamicins/pharmacology , Humans , Implants, Experimental , Nanostructures/ultrastructure , Osteoblasts/cytology , Osteoblasts/drug effects , Osteoblasts/metabolism , Osteomyelitis/pathology , Rabbits , Radiography , Rats , Rats, Wistar , Staphylococcus aureus/drug effects , Tibia/diagnostic imaging , Tibia/drug effects , Tibia/microbiology , Tibia/pathology
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