Review of Access Control Model

Access control is one of the core problems in data management system.In this paper,the system requirements were described in three aspects:the traditional access control model,the access control model in the Internet era and the access control model in the cloud computing environment.Meanwhile,the corresponding major models were listed and their characteristics and problems were analyzed.Finally,the development trend of the corresponding model was proposed.

A Temporal Multi-Tenant RBAC Model for Collaborative Cloud Services

Multi-tenant collaboration brings the challenge to access control in cloud computing environment.Based on the multi-tenant role-based access control(MT-RBAC)model,a Temporal MT-RBAC(TMT-RBAC)model for collaborative cloud services is proposed.It adds the time constraint between trusted tenants,including usable role time constraint based on both calendar and interval time.Analysis shows that the new model strengthens the presentation ability of MT-RBAC model,achieves the finer-grained access control,reduces the management costs and enhances the security of multi-tenant collaboration in cloud computing environment.

A Multi-Tenant Usage Access Model for Cloud Computing

Most cloud services are built with multi-tenancy which enables data and configuration segregation upon shared infrastructures.It offers tremendous advantages for enterprises and service providers.It is anticipated that this situation will evolve to foster cross-tenant collaboration supported by Authorization as a service.To realize access control in a multi-tenant cloud computing environment,this study proposes a multi-tenant cloud computing access control model based on the traditional usage access control model by building trust relations among tenants.The model consists of three sub-models,which achieve trust relationships between tenants with different granularities and satisfy the requirements of different application scenarios.With an established trust relation in MT-UCON(Multi-tenant Usage Access Control),the trustee can precisely authorize cross-tenant accesses to the trustor’s resources consistent with constraints over the trust relation and other components designated by the trustor.In addition,the security of the model is analyzed by an information flow method.The model adapts to the characteristics of a dynamic and open multi-tenant cloud computing environment and achieves fine-grained access control within and between tenants.

Lattice expansion enables interstitial doping to achieve a high average ZT in n-type PbS

Lead sulfide(PbS)presents large potential in thermoelectric application due to its earth-abundant S element.However,its inferior average ZT(ZTave)value makes PbS less competitive with its analogs PbTe and PbSe.To promote its thermoelectric performance,this study implements strategies of continuous Se alloying and Cu interstitial doping to synergistically tune thermal and electrical transport properties in n-type PbS.First,the lattice parameter of 5.93Åin PbS is linearly expanded to 6.03Åin PbS_(0.5)Se_(0.5)with increasing Se alloying content.This expanded lattice in Se-alloyed PbS not only intensifies phonon scattering but also facilitates the formation of Cu interstitials.Based on the PbS_(0.6)Se_(0.4)content with the minimal lattice thermal conductivity,Cu interstitials are introduced to improve the electron density,thus boosting the peak power factor,from 3.88μW cm^(−1)K^(−2)in PbS_(0.6)Se_(0.4)to 20.58μW cm^(−1)K^(−2)in PbS0.6Se0.4−1%Cu.Meanwhile,the lattice thermal conductivity in PbS_(0.6)Se_(0.4)−x%Cu(x=0-2)is further suppressed due to the strong strain field caused by Cu interstitials.Finally,with the lowered thermal conductivity and high electrical transport properties,a peak ZT~1.1 and ZTave~0.82 can be achieved in PbS_(0.6)Se_(0.4)−1%Cu at 300–773K,which outperforms previously reported n-type PbS.

Integrative analysis of the transcriptome and metabolome reveals the importance of hepatokine FGF21 in liver aging

Aging is a contributor to liver disease.Hence,the concept of liver aging has become prominent and has attracted considerable interest,but its underlying mechanism remains poorly understood.In our study,the internal mechanism of liver aging was explored via multi-omics analysis and molecular experiments to support future targeted therapy.An aged rat liver model was established with D-galactose,and two other senescent hepatocyte models were established by treating HepG2 cells with D-galactose and H2O2.We then performed transcriptomic and metabolomic assays of the aged liver model and transcriptome analyses of the senescent hepatocyte models.In livers,genes related to peroxisomes,fatty acid elongation,and fatty acid degradation exhibited down-regulated expression with aging,and the hepatokine Fgf21 expression was positively correlated with the down-regulation of these genes.In senescent hepatocytes,similar to the results found in aged livers,FGF21 expression was also decreased.Moreover,the expressions of cell cycle-related genes were significantly down-regulated,and the down-regulated gene E2F8 was the key cell cycle-regulating transcription factor.We then validated that FGF21 overexpression can protect against liver aging and that FGF21 can attenuate the declines in the antioxidant and regenerative capacities in the aging liver.We successfully validated the results from cellular and animal experiments using human liver and blood samples.Our study indicated that FGF21 is an important target for inhibiting liver aging and suggested that pharmacological prevention of the reduction in FGF21 expression due to aging may be used to treat liver aging-related diseases.

Comparative sorption and desorption behaviors of PFHx S and PFOS on sequentially extracted humic substances

The sorption and desorption behaviors of two perfluoroalkane sulfonates（PFSAs）, including perfluorohexane sulfonate（PFHx S） and perfluorooctane sulfonate（PFOS） on two humic acids（HAs） and humin（HM）, which were extracted from a peat soil, were investigated. The sorption kinetics and isotherms showed that the sorption of PFOS on the humic substances（HSs） was much higher than PFHx S. For the same PFSA compound, the sorption on HSs followed the order of HM 〉 HA2 〉 HA1. These suggest that hydrophobic interaction plays a key role in the sorption of PFSAs on HSs. The sorption capacities of PFSAs on HSs were significantly related to their aliphaticity, but negatively correlated to aromatic carbons,indicating the importance of aliphatic groups in the sorption of PFSAs. Compared to PFOS,PFHx S displayed distinct desorption hysteresis, probably due to irreversible pore deformation after sorption of PFHx S. The sorption of the two PFSAs on HSs decreased with an increase in p H in the solution. This is ascribed to the electrostatic interaction and hydrogen bonding at lower p H. Hydrophobic interaction might also be stronger at lower p H due to the aggregation of HSs.

Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

Heavy metals are widely concerning because of their toxicity,persistence,non-degradation and bioaccumulation ability.Iluman health ambient water quality criteria(AWQC)are specific levels of chemicals that can occur in water without harming human health.At present,most countries do not consider the effects of aquatic vegetables in deriving human health AWQC.Therefore,the intake of aquatic vegetables(Brasenia schreberi)was added to the derivation of human health AWQC and a health risk assessment for 13 heavy metals in Taihu Lake.The human health AWQC(consumption of water,fish and aquatic vegetables)values of 13 heavy metals ranged from 0.04(Cd)to 710.87μg/L(Sn),and the intake of B.schreberi had a very significant effect on the human health AWQC for Cu,with a more than 62-fold difference.The hazard quotients of As(2.8),Cd(1.6),Cr(1.4)and Cu(4.86)were higher than the safe level(HQ=1),indicating that As,Cd,Cr and Cu in Taihu Lake posed a significant health risk.Sensitivity analysis showed that the contribution rate of B.schreberi intake to the human health risk from Cu was 91.6%,and all results indicated that the risk of Cu in B.schreberi to human health should be of particular concern.This study adds the consideration of aquatic vegetable consumption to the traditional method of human health AWQC derivation and risk assessments for the first time,and this approach can promote the development of risk assessments and water quality criteria.

Clear mortality gap caused by graft macrosteatosis in Chinese patients after cadaveric liver transplantation

Background:Liver transplantation(LT)is one of the most effective surgical treatment for patients with end-stage liver disease.Steatosis is a contributor for inferior graft quality.But its impact and safety on transplantation was less assessed in Chinese patients.Methods:Graft steatosis and related information involved in recipients,donors and surgical procedures were retrospectively collected from 239 patients.Results:Donor macrosteatosis(MaS)caused about 2.14 and 2.80 folds of increment on patient and graft mortality.Dose-response analysis revealed prominent risk of grafts on overall patient/organ mortality when MaS content exceeded 10%(P<0.05).Noteworthy,deaths were only observed in MaS group when concurrent with extremely higher post-transplant alanine aminotransferase(ALT,64%).However,microsteatosis(MiS)grafts didn’t affect outcomes after LT.In a cohort of Chinese patients,MaS had comprehensive effects on post-transplant outcomes with relatively lower safety threshold at 10%.Mortality gap caused by MaS grafts was observed in patients with severer ischemia reperfusion injury.Conclusions:Our study revealled the graft MaS affected the post-transplant outcomes in lower risk cutoff in Chinese patients.Further study is worthy to validate these results and investigate inner mechanism under the phenomenon.

High T_(c) superconductivity in layered hydrides XH_(15) (X = Ca, Sr, Y, La) under high pressures

The theoretical predictions and experimental synthesis of H_(3)S and LaH_(10) superconductors with record high superconducting transition temperatures(T_(c))have promoted the hydrogen-based superconducors to be a research hotspot in the field of solid-state physics.Here,we predict an unprecedented layered structure CaH15,with high T_(c) of 189 K at 200 GPa using ab initio calculations.As concerns the novel structure,one layer is made of a hydrogen nonagon,the other layer consists of a Ca atom and six H_(2) molecular units surrounding the Ca atom.This layered structure was also found in SrH_(15),YH_(15),and LaH_(15) at high pressures,each materials exhibit high T_(c) especially YH_(15) can reach above 200 K at 220 GPa.It represents the second class of layered superhydrides with high value of Tc after pentagraphene like HfH10.

Recent Progress and Future Direction for the Application of Multiomics Data in Clinical Liver Transplantation

Omics data address key issues in liver transplantation(LT)as the most effective therapeutic means for end-stage liver disease.The purpose of this study was to review the current application and future direction for omics in LT.We reviewed the use of multiomics to elucidate the pathogenesis leading to LT and prognostication.Future directions with respect to the use of omics in LT are also described based on perspectives of surgeons with experience in omics.Significant molecules were identified and summarized based on omics,with a focus on post-transplant liver fibrosis,early allograft dysfunction,tumor recurrence,and graft failure.We emphasized the importance omics for clinicians who perform LTs and prioritized the directions that should be established.We also outlined the ideal workflow for omics in LT.In step with advances in technology,the quality of omics data can be guaranteed using an improved algorithm at a lower price.Concerns should be addressed on the translational value of omics for better therapeutic effects in patients undergoing LT.