Robust large-scale clustering based on correntropy.

With the explosive growth of data, how to efficiently cluster large-scale unlabeled data has become an important issue that needs to be solved urgently. Especially in the face of large-scale real-world data, which contains a large number of complex distributions of noises and outliers, the research on robust large-scale real-world data clustering algorithms has become one of the hottest topics. In response to this issue, a robust large-scale clustering algorithm based on correntropy (RLSCC) is proposed in this paper, specifically, k-means is firstly applied to generated pseudo-labels which reduce input data scale of subsequent spectral clustering, then anchor graphs instead of full sample graphs are introduced into spectral clustering to obtain final clustering results based on pseudo-labels which further improve the efficiency. Therefore, RLSCC inherits the advantages of the effectiveness of k-means and spectral clustering while greatly reducing the computational complexity. Furthermore, correntropy is developed to suppress the influence of noises and outlier the real-world data on the robustness of clustering. Finally, extensive experiments were carried out on real-world datasets and noise datasets and the results show that compared with other state-of-the-art algorithms, RLSCC can improve efficiency and robustness greatly while maintaining comparable or even higher clustering effectiveness.

Psychometric properties of patient-reported outcome measures of self-management for cancer survivors: a systematic review protocol using COSMIN methodology.

INTRODUCTION: Self-management is an important strategy for cancer survivors. Evaluating self-management is essential for planning nursing interventions that promote self-management and for measuring the contribution of nursing to health outcomes. Many patient-reported outcome measures (PROMs) have been designed and used to assess self-management in cancer survivors. However, it is unclear which PROM has the best reliability and validity. Therefore, the goal is to systematically review the psychometric properties of existing self-management PROMs and determine which PROM is best for cancer survivors. METHODS AND ANALYSIS: This systematic review will be conducted according to the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines for systematic reviews of PROMs. Ten electronic literature databases (PubMed, EMBASE and so on) and two websites for PROMs will be searched from inception to 1 March 2020. Studies testing the psychometric properties of PROMs assessing self-management for cancer survivors, published in either English or Chinese, will be included. Two independent reviewers determined the eligibility of the studies and will independently extract the data. Risk of bias will be assessed using the COSMIN risk-of-bias checklist, and the quality of the results will be assessed using specific COSMIN quality criteria. ETHICS AND DISSEMINATION: It is not necessary to obtain ethical approval for this systematic review protocol. The results will be published in a peer-reviewed journal and presented at a relevant conference. PROSPERO REGISTRATION NUMBER: CRD42020149120.

Multifunctions of dual Zn/Mg ion co-implanted titanium on osteogenesis, angiogenesis and bacteria inhibition for dental implants.

In order to improve the osseointegration and long-term survival of dental implants, it is urgent to develop a multifunctional titanium surface which would simultaneously have osteogeneic, angiogeneic and antibacterial properties. In this study, a potential dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed via plasma immersion ion implantation (PIII). The Zn/Mg-PIII surfaces were found to promote initial adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) via the upregulation of the gene expression of integrin α1 and integrin ß1. More importantly, it was revealed that Zn/Mg-PIII could increase Zn2+ and Mg2+ concentrations in rBMSCs by promoting the influx of Zn2+ and Mg2+ and inhibiting the outflow of Zn2+, and then could enhance the transcription of Runx2 and the expression of ALP and OCN. Meanwhile, Mg2+ ions from Zn/Mg-PIII increased Mg2+ influx by upregulating the expression of MagT1 transporter in human umbilical vein endothelial cells (HUVECs), and then stimulated the transcription of VEGF and KDR via activation of hypoxia inducing factor (HIF)-1α, thus inducing angiogenesis. In addition to this, it was discovered that zinc in Zn/Mg-PIII had certain inhibitory effects on oral anaerobic bacteria (Pg, Fn and Sm). Finally, the Zn/Mg-PIII implants were implanted in rabbit femurs for 4 and 12weeks with Zn-PIII, Mg-PIII and pure titanium as controls. Micro-CT evaluation, sequential fluorescent labeling, histological analysis and push-out test consistently demonstrated that Zn/Mg-PIII implants exhibit superior capacities for enhancing bone formation, angiogenesis and osseointegration, while consequently increasing the bonding strength at bone-implant interfaces. All these results suggest that due to the multiple functions co-produced by zinc and magnesium, rapid osseointegration and sustained biomechanical stability are enhanced by the novel Zn/Mg-PIII implants, which have the potential application in dental implantation in the future. STATEMENT OF SIGNIFICANCE: In order to enhance the rapid osseointegration and long-term survival of dental implants, various works on titanium surface modification have been carried out. However, only improving osteogenic activity of implants is not enough, because angiogenesis and bacteria inhibition are also very important for dental implants. In the present study, a novel dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed, which was found to have superior osteoinductivity, pro-angiogenic effects and inhibitory effects against oral anaerobes. Furthermore, synergistic effects of Zn/Mg ions on osteogenic differentiation of rBMSCs and the possible mechanism were discovered. In addition, rapid osseointegration and sustained biomechanical stability are greatly enhanced by Zn/Mg-PIII implants, which may have the potential application in dental implantation in the future. We believe this paper may be of particular interest to the readers.

Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus.

Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices.

Influence of sulfur content on bone formation and antibacterial ability of sulfonated PEEK.

Polyetheretherketone (PEEK) is desirable in orthopedic and dental applications because its mechanical properties are similar to those of natural bones but the bioinertness and inferior osteoconduction of PEEK have hampered many clinical applications. In this work, PEEK is sulfonated by concentrated sulfuric acid to fabricate a three-dimensional (3D) network. A hydrothermal treatment is subsequently conducted to remove the residues and the temperature is adjusted to obtain different sulfur concentrations. In vitro cell proliferation and real-time PCR analyses disclose enhanced proliferation and osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs) on the samples with small sulfur concentrations. The in vitro antibacterial evaluation reveals that all the sulfonated samples possess excellent resistance against Staphylococcus aureus and Escherichia coli. The in vivo rat femur implantation model is adopted and X-ray, micro-CT, and histological analyses indicate that not only the premeditated injected bacteria cells are sterilized, but also new bone forms around the samples with small sulfur concentrations. The in vitro and in vivo results reveal that the samples subjected to the hydrothermal treatment to remove excess sulfur have better osseointegration and antibacterial ability and PEEK modified by sulfonation and hydrothermal treatment is promising in orthopedic and dental applications.

Antibacterial activity, osteogenic and angiogenic behaviors of copper-bearing titanium synthesized by PIII&D.

Cu-bearing biomaterials have drawn considerable interest in hard tissue replacement. However, a better compromise between the biocompatibility and cytotoxicity of incorporated copper is still required. In this work, two types of Cu-bearing surfaces were obtained on Ti by altering the processing parameters during PIII&D. One with a certain amount of copper in metallic form on the Ti surface shows enhanced antibacterial ability, osteogenic and angiogenic capabilities, whereas unfavorable biocompatibility is observed from the other Ti surface in the presence of Cu-bearing nanoparticles. Disparate biological differences between two types of Cu-bearing Ti surfaces synthesized by the same single technique provides insights for better understanding of the underlying mechanism between the positive and negative bioeffects of Cu-bearing biomaterials.

Zn/Ag micro-galvanic couples formed on titanium and osseointegration effects in the presence of S. aureus.

Titanium implants possessing simultaneous osseointegration and antibacterial ability are desirable. In this work, three types of Zn/Ag micro-galvanic couples are fabricated on titanium by plasma immersion ion implantation to investigate the osseointegration and antibacterial effects as well as the involved mechanisms. The in vitro findings disclose enhanced proliferation, osteogenic differentiation, and gene expressions of the rat bone mesenchymal stem cells (rBMSCs), as well as good antibacterial ability on all three micro-galvanic couples. Excellent antimicrobial ability is also observed in vivo and the micro-CT and histological results reveal notable osseointegration in vivo despite the presence of bacteria. The Zn/Ag micro-galvanic couple formed on Zn/Ag dual-ion co-implanted titanium shows the best osseointegration as well as good antibacterial properties in vivo obtained from a rabbit tibia model. The difference among the three Zn/Ag micro-galvanic couples can be ascribed to the contact between the Ag NPs and Zn film, which affects the corrosion process. Our results indicate that the biological behavior can be controlled by the corrosion process of the Zn/Ag micro-galvanic couples.

Balancing the Osteogenic and Antibacterial Properties of Titanium by Codoping of Mg and Ag: An in Vitro and in Vivo Study.

To simultaneously enhance the osteogenic and antibacterial properties of titanium, we introduced magnesium (Mg), silver (Ag), or both by using the plasma immersion ion implantation (PIII) technique, producing three PIII sample groups, namely, Mg-doped titanium (Mg-PIII), Ag-doped titanium (Ag-PIII), and Mg and Ag codoped titanium (Mg/Ag-PIII). The in vitro antibacterial efficacy of Mg/Ag-PIII group was about 7-10% higher than that of Ag-PIII. In vitro and in vivo results demonstrated that osteogenic property of Mg/Ag PIII group was better than that of Ag-PIII or Mg-PIII. It was believed that the galvanic effects between Mg and Ag NPs played a key role in facilitating the release of Mg but reducing the release of silver, answering for the selective performances of the Mg/Ag-PIII group over bacterial and mammalian cells. This study demonstrated that the integration of multiple functional elements could be realized by the dual-source PIII technique, and in this case, the antibacterial properties and osteogenic property of titanium could be balanced.

Antimicrobial and osteogenic properties of silver-ion-implanted stainless steel.

Prevention of implant loosening and infection is crucial to orthopedic and dental surgeries. In this work, the surface of stainless steel (SS) was modified by silver-sourced plasma immersion ion implantation (Ag-PIII). Metallic silver nanoparticles with various diameters and distributions were fabricated on the SS surfaces after treatment with Ag-PIII for 0.5 and 1.5 h, respectively. The osteogenic activity and antimicrobial properties of SS before and after Ag-PIII treatment were evaluated using in vitro and in vivo tests. The results demonstrated that Ag-PIII treatment not only promoted the antibacterial activity of SS but also enhanced the osteogenic differentiation of human bone marrow stromal cells.

Calcium Plasma Implanted Titanium Surface with Hierarchical Microstructure for Improving the Bone Formation.

Introducing hierarchical microstructure and bioactive trace elements simultaneously onto the surface of titanium implant is a very effective way to improve the osseointegration between bone and implant. In this work, hierarchical topography was prepared on Ti surface via acid etching and sandblasting (SLA) to form micropits and microcavities then underwent Ca plasma immersion ion implantation (Ca-PIII) process. The surface wettability and roughness did not change obviously before and after Ca-PIII process. The in vitro evaluations including cell adhesion, activity, alkaline phosphatase (ALP), osteogenic genes (Runx2, OSX, ALP, BSP, Col1a1, OPN, and OC), and protein (BSP, Col1a1, OPN, and OC) expressions revealed that the introduction of Ca ions onto the surface of SLA-treated Ti can promote greater osteoblasts adhesion, spread and proliferation, which in return further accelerated the maturation and mineralization of osteoblasts. More importantly, in vivo evaluations including Micro-CT evaluation, histological observations, push-out test, sequential fluorescent labeling and histological observations verified that Ca-SLA-treated Ti implants could efficiently promote new bone formation in early times. These promising results suggest that Ca-SLA-treated Ti has the potential for future application in orthopedic field.

Graphene film-functionalized germanium as a chemically stable, electrically conductive, and biologically active substrate.

As a microelectronics material, germanium (Ge) has attracted wide interest for semiconductor devices (like biosensors) since its usage to build the first transistor. In this study, large-area monolayer graphene film was directly in situ deposited on a Ge substrate by the chemical vapor deposition (CVD) method. The aim of this study is to explore whether a graphene overlayer on Ge can influence its surface properties. The quality and homogeneity of the graphene film were investigated by Raman spectroscopy and transmission electron microscopy (TEM). The graphene overlayer was demonstrated to act as a protective layer for Ge to improve its corrosion resistance. Compared to bare Ge, graphene film-modified Ge can up-regulate gene expressions of osteogenic markers of mesenchymal stem cells, confirming the enhanced biological activity. Meanwhile, the graphene film also showed good antibacterial ability presumably due to the charge transfer to extract electrons from the bacterial membrane. We hope this work can provide new insights for surface modification and functionalization of Ge-based biosensors and medical devices to better meet clinical needs. The concept of utilizing graphene as a protective, conductive and bioactive layer might provide a viable alternative convenient for further usage of implantable Ge-based biomedical devices.

In vitro and in vivo anti-biofilm effects of silver nanoparticles immobilized on titanium.

Prevention of periprosthetic infection (PPI) by inhibiting biofilm formation on prostheses is crucial to orthopedic surgery. In this work, silver nanoparticles (Ag NPs) are fabricated in situ and immobilized on titanium by silver plasma immersion ion implantation (PIII). The anti-biofilm activity rendered by the immobilized Ag NPs is assessed using Staphylococcus epidermidis, a biofilm producing strain, in vitro and in vivo. The immobilized Ag NPs show no apparent cytotoxicity but reduce biofilm formation in vitro by inhibiting bacteria adhesion and icaAD transcription. The immobilized Ag NPs offer a good defense against multiple cycles of bacteria attack in vitro, and the mechanism is independent of silver release. Radiographic assessment, microbiological cultures, and histopathological results demonstrate the ability of the functionalized surface against bacterial infection to reduce the risk of implant-associated PPI.

Synergistic effects of dual Zn/Ag ion implantation in osteogenic activity and antibacterial ability of titanium.

Zinc (Zn) and silver (Ag) are co-implanted into titanium by plasma immersion ion implantation. A Zn containing film with Ag nanoparticles (Ag NPs) possessing a wide size distribution is formed on the surface and the corrosion resistance is improved due to the micro-galvanic couples formed by the implanted Zn and Ag. Not only are the initial adhesion, spreading, proliferation and osteogenic differentiation of rBMSCs observed from the Zn/Ag implanted Ti in vitro, but also bacteria killing is achieved both in vitro and in vivo. Electrochemical polarization and ion release measurements suggest that the excellent osteogenic activity and antibacterial ability of the Zn/Ag co-implanted titanium are related to the synergistic effect resulting from the long-range interactions of the released Zn ions and short-range interactions of the embedded Ag NPs. The Zn/Ag co-implanted titanium offers both excellent osteogenic activity and antibacterial ability and has large potential in orthopedic and dental implants.

Osteogenic activity and antibacterial effect of zinc ion implanted titanium.

Titanium (Ti) and its alloys are widely used as orthopedic and dental implants. In this work, zinc (Zn) was implanted into oxalic acid etched titanium using plasma immersion ion implantation technology. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to investigate the surface morphology and composition of Zn-implanted titanium. The results indicate that the depth profile of zinc in Zn-implanted titanium resembles a Gaussian distribution, and zinc exists in the form of ZnO at the surface whereas in the form of metallic Zn in the interior. The Zn-implanted titanium can significantly stimulate proliferation of osteoblastic MC3T3-E1 cells as well as initial adhesion, spreading activity, ALP activity, collagen secretion and extracellular matrix mineralization of the rat mesenchymal stem cells. The Zn-implanted titanium presents partly antibacterial effect on both Escherichia coli and Staphylococcus aureus. The ability of the Zn-implanted titanium to stimulate cell adhesion, proliferation and differentiation as well as the antibacterial effect on E. coli can be improved by increasing implantation time even to 2 h in this work, indicating that the content of zinc implanted in titanium can easily be controlled within the safe concentration using plasma immersion ion implantation technology. The Zn-implanted titanium with excellent osteogenic activity and partly antibacterial effect can serve as useful candidates for orthopedic and dental implants.

Comparison of NMR simulations of porous media derived from analytical and voxelized representations.

We develop and compare two formulations of the random-walk method, grain-based and voxel-based, to simulate the nuclear-magnetic-resonance (NMR) response of fluids contained in various models of porous media. The grain-based approach uses a spherical grain pack as input, where the solid surface is analytically defined without an approximation. In the voxel-based approach, the input is a computer-tomography or computer-generated image of reconstructed porous media. Implementation of the two approaches is largely the same, except for the representation of porous media. For comparison, both approaches are applied to various analytical and digitized models of porous media: isolated spherical pore, simple cubic packing of spheres, and random packings of monodisperse and polydisperse spheres. We find that spin magnetization decays much faster in the digitized models than in their analytical counterparts. The difference in decay rate relates to the overestimation of surface area due to the discretization of the sample; it cannot be eliminated even if the voxel size decreases. However, once considering the effect of surface-area increase in the simulation of surface relaxation, good quantitative agreement is found between the two approaches. Different grain or pore shapes entail different rates of increase of surface area, whereupon we emphasize that the value of the "surface-area-corrected" coefficient may not be universal. Using an example of X-ray-CT image of Fontainebleau rock sample, we show that voxel size has a significant effect on the calculated surface area and, therefore, on the numerically simulated magnetization response.

Scale-similarity model for Lagrangian velocity correlations in isotropic and stationary turbulence.

A scale-similarity model for Lagrangian two-point, two-time velocity correlations (LVCs) in isotropic turbulence is developed from the Kolmogorov similarity hypothesis. It is a second approximation to the isocontours of LVCs, while the Smith-Hay model is only a first approximation. This model expresses the LVC by its space correlation and a dispersion velocity. We derive the analytical expression for the dispersion velocity from the Navier-Stokes equations using the quasinormality assumption. The dispersion velocity is dependent on enstrophy spectra and shown to be smaller than the sweeping velocity for the Eulerian velocity correlation. Therefore, the Lagrangian decorrelation process is slower than the Eulerian decorrelation process. The data from direct numerical simulation of isotropic turbulence support the scale-similarity model: the LVCs for different space separations collapse into a universal form when plotted against the separation axis defined by the model.

[Association of the MspI polymorphism of cytochrome P4501A1 gene and smoking to the susceptibility to coronary artery disease].

OBJECTIVE: To investigate the association of MspI polymorphism of Cytochrome P4501A1 (CYP1A1) gene and smoking to the susceptibility to coronary artery disease (CAD). METHODS: The genotypes of CYP1A1 MspI site were detected using the methods of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) in 349 cases with CAD and 404 non-CAD as controls. CAD diagnosis was confirmed by coronary angiograms. Genetic risk of CYP1A1 genotypes was analyzed by smoking index (SI). RESULTS: The frequency of the predominant homozygotes TT, heterozygotes TC and the rare homozygotes CC in CAD group were not different with that of the controls (chi(2) = 3.224, P = 0.200). But in the smokers, the frequency of CC in CAD group was higher than that of non-CAD group (P = 0.002), while its odds ratio was 3.142 [95% confidence interval (CI) 1.481 - 6.668]. The odds ratio of genotype CC and heterozygote TC was 2.215 (95% CI 1.087 - 4.510) in the low dose cigarette smoking group, and was 1.407 (95% CI 0.709 - 2.791) in the high dose cigarette smoking group. CONCLUSION: Both MspI polymorphism of CYP1A1 gene and smoking exposure promote the development of CAD.

Polymorphisms in the coagulation factor VII gene and the risk of myocardial infarction in patients undergoing coronary angiography.

OBJECTIVE: To investigate whether coagulation factor VII (FVII) polymorphisms play a role in the pathogenesis of coronary artery disease (CAD) and/or myocardial infarction (MI) in a series of Hans. METHODS: The Arg(353)Gln and HVR4 polymorphisms of FVII gene were determined in 374 patients undergoing selective coronary angiography by PCR and restriction fragment length polymorphism assay. RESULTS: The FVII genotype distribution was in accordance with Hardy-Weinberg equilibrium. The frequencies of FVII genotypes or alleles did not show significant differences between the CAD group and the controls or between the males and the females. The frequencies of carriers of the Gln(353) allele and (Arg/Gln + Gln/Gln) genotypes were significantly higher in the CAD patients without MI than in those with MI (P = 0.031, odds ratio 0.37, 95% CI: 0.15 - 0.94). However, HVR4 polymorphisms were not significantly different between the two groups (P > 0.05). CONCLUSION: Carrying the F VII Gln(353) gene may be a protective factor against MI in the Chinese Hans.

Polymorphisms in the genes for coagulation factor II, V, VII in patients undergoing coronary angiography.

OBJECTIVE: To determine whether polymorphisms in the genes for coagulation factor II, V, VII could predispose an individual to increase risk for coronary artery disease (CAD) and/or myocardial infarction (MI) in Chinese. METHODS: We screened coagulation factor II(G20210A),V(G1691A),VII (R353Q and HVR4) genotype in 374 patients undergoing coronary angiography by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) assay. RESULTS: The R353Q and HVR4 genotype of the factor VII distribution was in accordance with Hardy-Weinberg equilibrium. The frequencies of FVII genotype or allele did not show statistically significant differences between CAD group and controls or between male and female. The frequencies of the Q allele and (RQ + QQ) genotype were significantly higher among the CAD patients without myocardial infarction (MI) history than among those with MI history (P < 0.05). However, HVR4 polymorphism was not significantly different within groups. We only find one normal control of factor II (G20210A) mutation. No coagulation factor V(G1691A) mutation was found in the CAD patients and controls. CONCLUSION: The factor II(G20210A) ,V(G1691A) mutation is absent and may not be a major genetic factor for CAD and/or MI; the Q allele of the R353Q polymorphism of the factor VII gene may be a protective genetic factor against myocardial infarction in Chinese.