Noise-adaptive synthetic oversampling technique

Applied Intelligence - In the field of supervised learning, the problem of class imbalance is one of the most difficult problems, and has attracted a great deal of research attention in recent...     

An effective approach for maintenance of pre-large-based frequent-itemset lattice in incremental mining

Incremental mining has attracted the attention of many researchers due to its usefulness in online applications. Many algorithms have thus been proposed for incrementally mining frequent itemsets. Maintaining a frequent-itemset lattice (FIL) is difficult for databases with large numbers of frequent itemsets, especially huge databases, due to the storage of links of nodes in the lattice. However, generating association rules from a FIL has been shown to be more effective than traditional methods such as directly generating rules from frequent itemsets or frequent closed itemsets. Therefore, when the number of frequent itemsets is not huge (i.e., they can be stored in the lattice without excessive memory overhead), the lattice-based approach outperforms approaches which mine association rules from frequent itemsets/frequent closed itemsets. However, incremental algorithms for building FILs have not yet been proposed. This paper proposes an effective approach for the maintenance of a FIL based on the pre-large concept in incremental mining. The building process of a FIL is first improved using two proposed theorems regarding the paternity relation between two nodes in the lattice. An effective approach for maintaining a FIL with dynamically inserted data is then proposed based on the pre-large and the diffset concepts. The experimental results show that the proposed approach outperforms the batch approach for building a FIL in terms of execution time.     

Facilitating GL13K Peptide Grafting on Polyetheretherketone via 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide: Surface Properties and Antibacterial Activity

In the present work, the antimicrobial peptide (AMP) of GL13K was successfully coated onto a polyetheretherketone (PEEK) substrate to investigate its antibacterial activities against Staphylococcus aureus (S. aureus) bacteria. To improve the coating efficiency, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was mixed with a GL13K solution and coated on the PEEK surface for comparison. Both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) data confirmed 30% greater peptide coating on PEEK/GL13K-EDC than PEEK without EDC treatment. The GL13K graft levels are depicted in the micrograms per square centimeter range. The PEEK/GL13K-EDC sample showed a smoother and lower roughness (Rq of 0.530 µm) than the PEEK/GL13K (0.634 µm) and PEEK (0.697 µm) samples. The surface of the PEEK/GL13K-EDC was more hydrophilic (with a water contact angle of 24°) than the PEEK/GL13K (40°) and pure PEEK (89°) samples. The pure PEEK disc did not exhibit any inhibition zone against S. aureus. After peptide coating, the samples demonstrated significant zones of inhibition: 28 mm and 25 mm for the PEEK/GL13K-EDC and PEEK/GL13K samples, respectively. The bacteria-challenged PEEK sample showed numerous bacteria clusters, whereas PEEK/GL13K contained a little bacteria and PEEK/GL13K-EDC had no bacterial attachment. The results confirm that the GL13K peptide coating was able to induce antibacterial and biofilm-inhibitory effects. To the best of our knowledge, this is the first report of successful GL13K peptide grafting on a PEEK substrate via EDC coupling. The present work illustrates a facile and promising coating technique for a polymeric surface to provide bactericidal activity and biofilm resistance to medical implantable devices.     

提高水分生产率和农业生产能力是我们追求的目标

我长期从事水稻研究工作,特别是对水稻水管理方面做了许多研究.水稻节水灌溉这个项目的研究意义非常大,因为我们知道水资源短缺使许多国家面临挑战,如何解决水危机,是许多专家和相关国际组织共同关注和探讨的问题.     

Synthesis of urea-pyridyl ligand functionalized mesoporous silica hybrid material for hydrophobic and hydrophilic drug delivery application

In this work, we propose the synthesis of urea-pyridyl (UPy) ligand functionalized mesoporous silica hybrid material as novel and effective drug delivery system for loading/release of both hydrophobic and hydrophilic drugs. For the synthesis of UPy ligand functionalized mesoporous silica hybrid material, the combination of sol–gel co-condensation technique and post silica surface modification method were adapted. The prepared UPy ligand functionalized mesoporous silica hybrid (UPy-MSH) material was characterized by X-ray diffraction, Fourier-transform infrared, N₂ adsorption–desorption analysis. The material morphology and mesopore channels were observed by scanning and transmission electron microscopic analyses. The content of modified organic ligand functionalities present in the UPy-MSH material surface was determined by thermogravimetric analysis. The hydrophilic anticancer drug, 5-Fluorouracil and the hydrophobic anti-inflammatory drug, Ibuprofen was used as a model drugs to determine the loading and pH-responsive release efficiency of the synthesized UPy-MSH material under different pH (pH 7.4 and 5.0) conditions, respectively. In addition, the biocompatibility of the UPy-MSH material was evaluated on MDA-MB-231 cells. The experimental results depicted that the synthesized UPy-MSH material is biocompatible and has high drug loading capacity, selective and controlled release of specific drug with respect to the pH condition.     

Symmetric metamaterials based on flower-shaped structure

We proposed new models of metamaterials (MMs) based on a flower-shaped structure (FSS), whose “meta-atoms” consist of two flower-shaped metallic parts separated by a dielectric layer. Like the non-symmetric MMs based on cut-wire-pairs or electric ring resonators, the symmetrical FSS demonstrates the negative permeability at GHz frequencies. Employing the results, we designed a symmetric negative-refractive-index MM [a symmetric combined structure (SCS)], which is composed of FSSs and cross continuous wires. The MM properties of the FSS and the SCS are presented numerically and experimentally.     

Acid functionalization of carbon nanofibers

We have studied the effects of temperature (70–100°C), process duration (1–4 h), and the ratio of the acid mixture (concentrated HNO₃ and H₂SO₄ in the volume ratio 1: 3) volume to carbon nanofiber weight (70: 1 to 133: 1 ml/g) on the yield of functionalization products and their dispersibility in water. The results indicate that, with increasing temperature and process duration, the yield of functionalization products decreases, and their concentration (“solubility”) in the aqueous dispersion increases: from 1.2–1.3 to 11.0 mg/ml when the yield decreases from 71–89 to 30%. We present the first measurements of the gas volume evolved during functionalization and show that it increases with increasing temperature and process duration, reaching 500–600 ml/g carbon under the most severe conditions. The major component of the reaction gases is CO₂ (over 50 vol %).     

Facile synthesis of ZnBi<Subscript>2</Subscript>O<Subscript>4</Subscript>-graphite composites as highly active visible-light photocatalyst for the mineralization of rhodamine B

Novel highly active visible-light photocatalysts in the form of zinc bismuth oxide (ZnBi₂O₄) and graphite hybrid composites were prepared by coupling via a co-precipitation method followed by calcination at 450 °C. The as-prepared ZnBi₂O₄-graphite hybrid composites were tested for the degradation of rhodamine B (RhB) solutions under visible-light irradiation. The existence of strong electronic coupling between the two components within the ZnBi₂O₄-graphite heterostructure suppressed the photogenerated recombination of electrons and holes to a remarkable extent. The prepared composite exhibited excellent photocatalytic activity, leading to more than 93% of RhB degradation at an initial concentration of 50mg·L^-1 with 1.0 g catalyst per liter in 150min. The excellent visible-light photocatalytic mineralization of ZnBi₂O₄-1.0graphite in comparison with pristine ZnBi₂O₄ could be attributed to synergetic effects, charge transfer between ZnBi₂O₄ and graphite, and the separation efficiency of the photogenerated electrons and holes. The photo-induced h+ and the superoxide anion were the major active species responsible for the photodegradation process. The results demonstrate the feasibility of ZnBi₂O₄-1.0graphite as a potential heterogeneous photocatalyst for environmental remediation.