An efficient confidentiality protection solution for pub/sub system

Publish/subscribe(pub/sub)systems are widely used in large-scale messaging systems due to their asynchronous and decoupled nature.With the population of pub/sub cloud services,the privacy protection problem of pub/sub systems has started to emerge,and events and subscriptions are exposed when executing event matching on untrustworthy cloud brokers.However,as the number of subscriptions increases,the effectiveness of the previous confidentiality protection approaches declines drastically.In this paper,we propose SBM(scalable blind matching),an effective confidentiality protection scheme for pub/sub systems.To the best of our knowledge,SBM is the first scheme that applies order-preserving encryption algorithm to protect the system’s confidentiality and ensure its scalability.In this scheme,SBM-I is highly effective in subscription matching but is unable to achieve ideal security IND-OCPA,whereas SBM-II is suggested to ensure system security and SGX is used to reduce interaction and boost ciphertext matching performance.The experiment demonstrates that this method has better matching performance compared to others:the average matching time of SBM-I is 3–4 orders of magnitude faster than the matching algorithm MP and SGX-based algorithm SCBR when the number of subscriptions is 500,000,and the average matching time of SBM-II is 40 times faster than MP and 24 times than SCBR.

Specific heat treatment of selective laser melted Ti-6AI-4V for biomedical applications

The ductility of as-fabricated Ti-6AI-4V fails far short of the requirements for biomedical titanium alloy implants and the heat treatment remains the only applicable option for improvement of their mechanical properties. In the present study, the decomposition of as-fabricated martensite was investigated to provide a general understanding on the kinetics of its phase transformation. The decomposition of as- fabricated martensite was found to be slower than that of water-quenched martensite. It indicates that specific heat treatment strategy is needed to be explored for as.fabricated Ti-6AI-4V. Three strategies of heat treatment were proposed based on different phase transformation mechanisms and classified as subtransus treatment, supersolvus treatment and mixed treatment. These specific heat treatments were conducted on selective laser melted samples to investigate the evolutions of microstructure and mechanical properties. The subtransus treatment leaded to a basket-weave structure without changing the morphology of columnar prior β grains. The supersolvus treatment resulted in a lamellar structure and equiaxed β grains. The mixed treatment yielded a microstructure that combines both features of the subtransus treatment and supersolvus treatment. The subtransus treatment is found to be the best choice among these three strategies for as.fabricated Ti-6AI-4V to be used as biomedical implants.

Comparing the regeneration potential between PLLA/Aragonite and PLLA/ Vaterite pearl composite scaffolds in rabbit radius segmental bone defects

Mussel-derived nacre and pearl,which are natural composites composed CaCO3 platelets and interplatelet organic matrix,have recently gained interest due to their osteogenic potential.The crystal form of CaCO3 could be either aragonite or vaterite depending on the characteristics of mineralization template within pearls.So far,little attention has been paid on the different osteogenic capacities between aragonite and vaterite pearl.In the current work,aragonite or vaterite pearl powders were incorporated into poly-L-lactic acid(PLLA)scaffold as bio-functional fillers for enhanced osteogenesis.In intro results revealed that PLLA/aragonite scaffold possessed stronger stimulatory effect on SaOS-2 cell proliferation and differentiation,evidenced by the enhanced cell viability,alkaline phosphatase activity,collagen synthesis and gene expressions of osteogenic markers including osteocalcin,osteopotin and bone sialoprotein.The bone regeneration potential of various scaffolds was evaluated in vivo employing a rabbit critical-sized radial bone defect model.The X-ray and micro-CT results showed that significant bone regeneration and bridging were achieved in defects implanted with composite scaffolds,while less bone formation and non-bridging were found for pure PLLA group.Histological evaluation using Masson's trichrome and hematoxylin/eosin(H&E)staining indicated a typical endochondral bone formation process conducted at defect sites treated with composite scaffolds.Through three-point bending test,the limbs implanted with PLLA/aragonite scaffold were found to bear significantly higher bending load compared to other two groups.Together,it is suggested that aragonite pearl has superior osteogenic capacity over vaterite pearl and PLLA/aragonite scaffold can be employed as a potential bone graft for bone regeneration.

Incorporation of silica nanoparticles to PLGA electrospun fibers for osteogenic differentiation of human osteoblast-like cells

The development of bone tissue engineering scaffolds still remains a challenging field,although various biomaterials have been developed for this purpose.Electrospinning is a promising approach to fabricate nanofibers with an interconnected porous structure,which can support cell adhesion,guide cell proliferation and regulate cell differentiation.The aim of this study is to fabricate composite fibers composed of poly(lactic-co-glycolic acid)(PLGA)and silica nanoparticles(NPs)via electrospinning and investigate the effect of PLGA/SiO_(2)composite fibers on the cellular response of osteoblast-like cells(SaOS-2 cells).SEM and EDX analysis showed that silica NPs were homogenously dispersed in the composite fibers.The mechanical behavior of the fibers showed that silica NPs acted as reinforcements at concentrations of 2.5 and 5 mg/ml.The incorporation of silica NPs led to enhancement of cell attachment and spreading on PLGA/SiO_(2)composite fibers.SaOS-2 cells cultured on PLGA/SiO_(2)composite fibers exhibited increased alkaline phosphatase activity,collagen secretion and bone nodules formation.The bone nodules formation of SaOS-2 cells increased along with the amount of incorporated silica NPs.The present findings indicate that PLGA/SiO_(2)composite fibers can stimulate osteogenic differentiation of SaOS-2 cells and may be a promising candidate scaffold for bone tissue engineering.

Nanoparticles and their effects on differentiation of mesenchymal stem cells

Over the past decades,advancements in nanoscience and nanotechnology have resulted in numerous nanomedicine platforms.Various nanoparticles,which exhibit many unique properties,play increasingly important roles in the field of biomedicine to realize the potential of nanomedicine.Due to the capacity of self-renewal and multilineage mesenchymal differentiation,mesenchymal stem cells(MSCs)have been widely used in the area of regenerative medicine and in clinical applications due to their potential to differentiate into various lineages.There are several factors that impact the differentiation of MSCs into different lineages.Many types of biomaterials such as polymers,ceramics,and metals are commonly applied in tissue engineering and regenerative therapies,and they are continuously refined over time.In recent years,along with the rapid development of nanotechnology and nanomedicine,nanoparticles have been playing more and more important roles in the fields of biomedicine and bioengineering.The combined use of nanoparticles and MSCs in biomedicine requires greater knowledge of the effects of nanoparticles on MSCs.This review focuses on the effects of four inorganic or metallic nanoparticles(hydroxyapatite,silica,silver,and calcium carbonate),which are widely used as biomaterials,on the osteogenic and adipogenic differentiation of MSCs.In this review,the cytotoxicity of these four nanoparticles,their effects on osteogenic/adipogenic differentiation of MSCs and the signalling pathways or transcription factors involved are summarized.In addition,the chemical composition,size,shape,surface area,surface charge and surface chemistry of nanoparticles,have been reported to impact cellular behaviours.In this review,we particularly emphasize the influence of their size on cellular responses.We envision our review will provide a theoretical basis for the combined application of MSCs and nanoparticles in biomedicine.

Microstructure and inclusion of Ti-6AI-4V fabricated by selective laser melting

Selective laser melting （SLM） was used in fabricating the dense part from pre-alloyed Ti-6Al-4V powder. The microstructural evolution and inclusion formation of as-fabricated part were characterized in depth. The microstructure was characterized by features of columnar prior β grains and acicular martensite α＇. High density defects such as dislocations and twins can be produced in SLM process. Investigations on the inclusions find out that hard alpha inclusion, amorphous CaO and microcrystalline Al2O3 are three main inclusions formed in SLM. The inclusions formed at some specific sites on melt pool surface. The microstructural evolution and inclusion formation of as-fabricated material are closely related to the SLM process.