Predicting surgical site infections using a novel nomogram in patients with hepatocelluar carcinoma undergoing hepatectomy

BACKGROUND Surgical site infections (SSI) remain a major cause of morbidity after hepatectomy for hepatocellular carcinoma (HCC).AIM To identify the risk factors associated with SSI,and develop a nomogram to predict SSI among patients undergoing hepatectomy.METHODS We retrospectively reviewed the data of patients diagnosed with HCC undergoing hepatectomy at two academic institutions in China,and evaluated the occurrence of SSI.Independent risk factors for SSI were identified using univariate and multivariate analyses.Based on these independent risk factors,a nomogram was established using the data of patients in the first institution,and was validated using data from an external independent cohort from the second institution.RESULTS The nomogram was established using data from 309 patients,whereas the validation cohort used data from 331 patients.The operation duration,serum albumin level,repeat hepatectomy,and ASA score were identified as independent risk factors.The concordance index (C-index) of the nomogram for SSI prediction in the training cohort was 0.86;this nomogram also performed well in the external validation cohort,with a C-index of 0.84.Accordingly,we stratified patients into three groups,with a distinct risk range based on the nomogram prediction,to guide clinical practice.CONCLUSION Our novel nomogram offers good preoperative prediction for SSIs in patients undergoing hepatectomy.

Economic Model Predictive Control for Hot Water Based Heating Systems in Smart Buildings

This paper presents a study to optimize the heating energy costs in a residential building with varying electricity price signals based on an Economic Model Predictive Controller (EMPC). The investigated heating system consists of an air source heat pump (ASHP) incorporated with a hot water tank as active Thermal Energy Storage (TES), where two optimization problems are integrated together to optimize both the ASHP electricity consumption and the building heating consumption utilizing a heat dynamic model of the building. The results show that the proposed EMPC can save the energy cost by load shifting compared with some reference cases.

Enhancing Wind Power Integration through Optimal Use of Flexibility in Multi-Carrier Energy Systems from the Danish Perspective

Denmark’ goal of being independent of fossil energy sources in 2050 puts forward great demands on all energy subsystems (electricity, heat, gas and transport, etc.) to be operated in a holistic manner. The Danish experience and challenges of wind power integration and the development of district heating systems are summarized in this paper. How to optimally use the cross-sectoral flexibility by intelligent control (model predictive control-based) of the key coupling components in an integrated heat and power system including electrical heat pumps in the demand side, and thermal storage applications in buildings is investigated.

Situation Awareness of Active Distribution Network:Roadmap,Technologies,and Bottlenecks

With the rapid development of local generation and demand response,the active distribution network(ADN),which aggregates and manages miscellaneous distributed resources,has moved from theory to practice.Secure and optimal operations now require an advanced situation awareness(SA)system so that operators are aware of operation states and potential risks.Current solutions in distribution supervisory control and data acquisition(DSCADA)as well as the distribution automation system(DAS)generally are not able to meet the technology requirements of SA.In this paper,the authors’participation in the project of developing an SA system as the basic component of a practical active distribution management system(ADMS)deployed in Beijing,China,is presented.This paper reviews the ADN’s development roadmap by illustrating the changes that are made in elements,topology,structure,and control scheme.Taking into consideration these hardware changes,a systematic framework is proposed for the main components and the functional hierarchy of an SA system for the ADN.The SA system’s implementation bottlenecks are also presented,including,but not limited to issues in big data platform,distribution forecasting,and security evaluation.Potential technology solutions are also provided.

Value assessment of hydrogen-based electrical energy storage in view of electricity spot market

Hydrogen as an energy carrier represents one of the most promising carbon-free energy solutions.The ongoing development of power-to-gas(Pt G)technologies that supports large-scale utilization of hydrogen is therefore expected to support hydrogen economy with a final breakthrough.In this paper,the economic performance of a MW-sized hydrogen system,i.e.a composition of water electrolysis,hydrogen storage,and fuel cell combined heat and power plant(FCCHP),is assessed as an example of hydrogen-based bidirectional electrical energy storage(EES).The analysis is conducted in view of the Danish electricity spot market that has high price volatility due to its high share of wind power.An economic dispatch model is developed as a mixed-integer programming(MIP)problem to support the estimation of variable cost of such a system taking into account a good granularity of the technical details.Based on a projected technology improvement by 2020,sensitivity analysis is conducted to illustrate how much the hydrogen-based EES is sensitive to variations of the hydrogen price and the capacity of hydrogen storage.

Self-generating nanogaps for highly effective surface-enhanced Raman spectroscopy

The fabrication of surface enhanced Raman spectroscopy(SERS)substrates with controlled high density hot spots still remains challenging.Herein,we report highly effective SERS substrates containing the self-generating(SG)nanogaps from polystyrene nanosphere monolayer through isotropic plasma etching.The emergence of multimode hot spots,i.e.,metal film over nanosphere(MFON)-like hot spots(closed gaps,0 nm),individual self-aligned hot spots(discrete gaps,>20 nm)and threedimensional(3D)hot spots(nanogaps,1-10 nm),makes the SG SERS substrates superior as compared to the traditional MFON or the well-ordered self-aligned SERS substrates in terms of enhancement,uniformity,and reproducibility.The SG SERS substrates can function as the excellent SERS platforms for trace molecule detection in the practical application fields.

A review of Danish integrated multi-energy system flexibility options for high wind power penetration

The current status of wind power and the energy infrastructure in Denmark is reviewed in this paper.The reasons for why Denmark is a world leader in wind power are outlined.The Danish government is aiming to achieve 100%renewable energy generation by 2050.A major challenge is balancing load and generation.In addition,the current and future solutions of enhancing wind power penetration through optimal use of cross-energy sector flexibility,so-called indirect electric energy storage options,are investigated.A conclusion is drawn with a summary of experiences and lessons learned in Denmark related to wind power development.

Room-temperature processing of silver submicron fiber mesh for flexible electronics

Ultrathin,patterned,conducting metallic fibers have been extensively studied as building blocks in flexible electronics.However,their scalable processing and attainment of patterns at room temperature is challenging.In this paper,we report on the patterning of ultra-long silver submicron fibers as woven mesh through the process of continuous draw spinning in the presence of ultraviolet(UV)treatment.The silver fibers can be directly intertwined on flexible substrates,such as polyethylene terephthalate(PET)and polyimide(PI).The as obtained silver submicron fiber mesh present excellent photoelectric properties(T=90%,R=9Ωsq^(−1))and outstanding flexibility and can be easily transferred on other surfaces.To demonstrate its application,flexible electrochromic smart window and infrared stealth film have been prepared.

富含S空位的二维SnS_(2)加速析氢反应

精确调控二维平面内的原子缺陷可有效调节二维材料的各种基本性质.本研究通过改变退火温度(250-350℃),实现了二维二硫化锡(SnS_(2))基面上硫(S)原子的精确敲除,得到了具有不同S空位浓度的SnS_(2)(Vs-SnS_(2)).当SnS_(2)在350℃下退火5h时,大量出现单S原子和双S原子空位形态,S空位浓度可达30.5%.在自制微芯片中测试了Vs-SnS_(2)的电催化析氢性能.S空位浓度达到30.5%的Vs-SnS_(2)表现出优异的催化性能,Tafel斜率达到74 mV dec^(-1),起始电位低至141 mV.通过理论计算对反应机制进行研究,结果表明,S原子的缺失促进了表面电荷调制,提高了SnS_(2)的导电性.此外,S空位导致Sn原子的不饱和配位,从而引起晶格畸变和电荷密度重新分布,更加有利于析氢反应.简而言之,通过控制退火温度可精确敲除特定原子、制造缺陷,可成为探索各种2D材料结构相关特性的一种有效策略.

Phase-Field Modeling of Hydrogen Diffusion and Trapping in Steels

Hydrogen embrittlement of steels is directly linked to hydrogen diffusion and trapping in the microstructure,which can hardly be precisely measured by modern experimental techniques.A phase-field model,in which a chemical potential well of hydrogen in the grain boundaries is introduced,is proposed to simulate hydrogen diffusion and trapping in the polycrystalline iron.It was interestingly found that grain boundaries,as connected trap sites,have a complex influence on the effective diffusivity of hydrogen,which are strongly linked to grain boundary diffusivity and binding energy.

Facilitating Water electrolysers for electricity-grid services in Europe through establishing standardized testing protocols

Electrolysers,which convert electricity into hydrogen,have the potential to offer a variety of electrical-grid services,therefore facilitating the integration of intermittent renewables into electrical grids.Among various activities that aim to unlock this hidden value,the 3-year European Union project QualyGridS launched in 2017 aims to establish standardized testing protocols for electrolysers to perform electricity-grid services.This paper shares experience and intermediate results of QualyGridS with respect to the testing protocols,test benches and testing results.The results of this work facilitate mutual understanding between the electricity industry and the hydrogen industry,support further development of the cross-sector testing standards,guide the design and selection of grid-service-oriented electrolyser applications and foster the transition towards a fossil-free-energy future based on high shares of hydrogen and other renewable solutions.

Artificial neural network based optimization of a six-step two-bed pressure swing adsorption system for hydrogen purification

The pressure swing adsorption(PSA)system is widely applied to separate and purify hydrogen from gaseous mixtures.The extended Langmuir equation fitted from the extended Langmuir-Freundlich isotherm has been used to predict the adsorption isothermal of hydrogen and methane on the zeolite 5A adsorbent bed.A six-step two-bed PSA model for hydrogen purification is developed and validated by comparing its simulation results with other works.The effects of the adsorption pressure,the P/F ratio,the adsorption step time and the pressure equalization time on the performance of the hydrogen purification system are studied.A four-step two-bed PSA model is taken into consideration,and the six-step PSA system shows higher about 13%hydrogen recovery than the four-step PSA system.The performance of the vacuum pressure swing adsorption(VPSA)system is compared with that of the PSA system,the VPSA system shows higher hydrogen purity than the PSA system.Based on the validated PSA model,a dataset has been produced to train the artificial neural network(ANN)model.The effects of the number of neurons in the hidden layer and the number of samples used for training ANN model on the predicted performance of ANN model are investigated.Then,the well-trained ANN model with 6 neurons in the hidden layer is applied to predict the performance of the PSA system for hydrogen purification.Multi-objective optimization of hydrogen purification system is performed based on the trained ANN model.The artificial neural network can be considered as a very effective method for predicting and optimizing the performance of the PSA system for hydrogen purification.