Solid-state batteries have recently raised strong interest in the scientific community as possible advancement of battery technology beyond commercial lithium ion due to the promise of high energy densities and improv...Solid-state batteries have recently raised strong interest in the scientific community as possible advancement of battery technology beyond commercial lithium ion due to the promise of high energy densities and improved safety[1].In the core of development of high-performance solid-state batteries,is the development of solid-state electrolytes,which should be both sufficiently ionically conductive and offer stable interphases with high-energy electrodes,such as alkali metals and silicon[2,3].Recently,potassium-ion batteries have emerged as an alternative to lithium-ion batteries as a remedy to limited resources and uneven distribution of lithium,as well as due to the fact that low standard electrode potentials of K/K^(+) electrodes should lead to high operation voltages,competitive to those observed in commercial lithium batteries[4-6].展开更多
Hydrogen is recognized as a clean energy carrier that can decarbonize heavy industry and the aviation system.However,the infrastructure is not yet ready for a hydrogen economy and large-scale hydrogen storage is neede...Hydrogen is recognized as a clean energy carrier that can decarbonize heavy industry and the aviation system.However,the infrastructure is not yet ready for a hydrogen economy and large-scale hydrogen storage is needed to balance the mismatch between supply and demand.Therefore,depleted gas fields have been proposed as suitable storage sites,given the presence of infrastructure and pipeline network for distribution and utilization.Attempts have been made to analyze the suitability of these reservoirs for hydrogen storage,with a focus on choosing higher temperature and salinity conditions to neutralize the effects of microbial activities as one of the main sources of hydrogen loss in the depleted gas reservoirs.However,thermochemical sulfate reduction(TSR)is activated at high temperatures and has a huge potential not only to consume hydrogen through abiotic reactions but also to generate a huge amount of H_(2)S.In this study,a onedimensional diffusion-based mass transport model was built using PHREEQC to highlight the potential challenges posed by the TSR in depleted gas fields.The results obtained indicated that the presence of iron minerals(pyrite and hematite)is crucial for H_(2)S generation through TSR reactions.An increase in temperature also leads to an increase in H_(2)S concentration in the brine and gas phase.However,since most of the H_(2)S formation comes from pyrite dissolution and pyrite dissolution is still strong at lower temperatures,a low temperature is not necessarily the best selection criterion to avoid H_(2)S formation.Thus,precautions must be taken to ensure that activation of TSR does not pose significant environmental problems.展开更多
This article provides a method by which the scour depth and scour width below pipelines,and the scour depth around single vertical piles as well as the time scales of scour for both structures due to bichromatic and b...This article provides a method by which the scour depth and scour width below pipelines,and the scour depth around single vertical piles as well as the time scales of scour for both structures due to bichromatic and bidirectional waves are calculated.The scour and time scale formulae summarized by Sumer and Fredsøe(2002)as well as the bottom shear stress formulae under bichromatic and bidirectional waves by Myrhaug et al.(2023)are used.Results for unidirectional bichromatic waves and symmetrically bidirectional monochromatic waves are provided,showing qualitative agreement with what is expected physically.Qualitative comparisons are made with the data from Schendel et al.’s(2020)small scale laboratory tests on scour around a monopile induced by directionally spread waves.Applications to related cases for pipelines are also suggested.In order to conclude regarding the validity of the method for pipelines and vertical piles,it is required to compare with data in its validity range.展开更多
During normal de-ballasting operations for floating docks,each ballast pump independently manages a specific group of ballast tanks.However,when a pump malfunctions,a connection valve between the two groups of ballast...During normal de-ballasting operations for floating docks,each ballast pump independently manages a specific group of ballast tanks.However,when a pump malfunctions,a connection valve between the two groups of ballast water systems is opened.This allows the adjacent pump to serve as a helper pump,simultaneously controlling two groups of ballast water systems.This study explores a full-scale floating dock’s dynamic behaviours during the de-ballasting operations under this situation through a numerical model.In the developed numerical model,the dock is described as a six-degree-of-freedom rigid body which is subjected to hydrostatic,hydrodynamic,and mooring loads.A hydraulic model of the piping network of the malfunctioning pump and the helper pump is proposed.A modified P-controller regulates opening angles of all tank valves for minimal pitch and roll.Two configurations of the floating dock,i.e.,a single floating dock and a floating dock with an onboard vessel,are considered.The numerical results show that the optimal helper pumps can be identified regarding the pumps’total de-ballasting capacity and the dock’s stability.The most severe scenarios can be determined in term of the dock’s maximum draught differences caused by its roll and pitch.The observed maximum draught differences remain small relative to the dock’s width,indicating the effectiveness of employing helper pumps and the proposed automatic ballast control strategy for one-pump malfunction scenarios.展开更多
Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehens...Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehensive physical simulation experiments were conducted under varied pressures,coupled with assessments of changes in mineral composition,ion concentrations,pore morphology,permeability,and sequestration capacity before and after experimentation.Simultaneously,a method using NMR T2spectra changes to measure pore volume shift and estimate CO_(2)sequestration is introduced.It quantifies CO_(2)needed for mineralization of soluble minerals.However,when CO_(2)dissolves in crude oil,the precipitation of asphaltene compounds impairs both seepage and storage capacities.Notably,the impact of dissolution and precipitation is closely associated with storage pressure,with a particularly pronounced influence on smaller pores.As pressure levels rise,the magnitude of pore alterations progressively increases.At a pressure threshold of 25 MPa,the rate of change in small pores due to dissolution reaches a maximum of 39.14%,while precipitation results in a change rate of-58.05%for small pores.The observed formation of dissolution pores and micro-cracks during dissolution,coupled with asphaltene precipitation,provides crucial insights for establishing CO_(2)sequestration parameters and optimizing strategies in low permeability reservoirs.展开更多
AIM:To investigate the epidemiological trends in inci-dence and mortality of perforated peptic ulcer(PPU)in a well-defined Norwegian population. METHODS:A retrospective,population-based,single-center,consecutive cohor...AIM:To investigate the epidemiological trends in inci-dence and mortality of perforated peptic ulcer(PPU)in a well-defined Norwegian population. METHODS:A retrospective,population-based,single-center,consecutive cohort study of all patients diag-nosed with benign perforated peptic ulcer.Included were both gastric and duodenal ulcer patients admitted to Stavanger University Hospital between January 2001 and December 2010.Ulcers with a malignant neoplasia diagnosis,verified by histology after biopsy or resection,were excluded.Patients were identified from the hospitals administrative electronic database using pertinent ICD-9 and ICD-10 codes(K25.1,K25.2,K25.5, K25.6,K26.1,K26.2,K26.5,K26.6).Additional searches using appropriate codes for relevant laparoscopic and open surgical procedures(e.g.,JDA 60,JDA 61,JDH 70 and JDH 71)were performed to enable a complete identification of all patients.Patient demographics,presentation patterns and clinical data were retrieved from hospital records and surgical notes.Crude and adjusted incidence and mortality rates were estimated by using national population demographics data. RESULTS:In the study period,a total of 172 patients with PPU were identified.The adjusted incidence rate for the overall 10-year period was 6.5 per 100 000 per year(95%CI:5.6-7.6)and the adjusted mortality rate for the overall 10-year period was 1.1 per 100 000 per year(95%CI:0.7-1.6).A non-significant decline in ad-justed incidence rate from 9.7 to 5.6 occurred during the decade.The standardized mortality ratio for the whole study period was 5.7(95%CI:3.9-8.2),while the total 30-d mortality was 16.3%.No difference in in-cidence or mortality was found between genders.However,for patients≥60 years,the incidence increased over 10-fold,and mortality more than 50-fold,compared to younger ages.The admission rates outside office hours were high with almost two out of three(63%) admissions seen at evening/night time shifts and/or during weekends.The observed seasonal variations in admissions were not statistically significant. CONCLUSION:The adjusted incidence rate,seasonal distribution and mortality rate was stable.PPU fre-quently presents outside regular work-hours.Increase in incidence and mortality occurs with older age.展开更多
The method of obtaining zircon samples affects estimation of the global U-Pb age distribution.Researchers typically collect zircons via convenience sampling and cluster sampling.When using these techniques,weight adju...The method of obtaining zircon samples affects estimation of the global U-Pb age distribution.Researchers typically collect zircons via convenience sampling and cluster sampling.When using these techniques,weight adjustments proportional to the areas of the sampled regions improve upon unweighted estimates.Here,grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb ages.Preliminary tests involve two age models.Model-1 uses the most precise U-Pb ages as the best ages.Model-2 uses the^(206)Pb/^(238)U age as the best age if it is less than a1000 Ma cutoff,otherwise it uses the^(207)Pb/^(206)Pb age as the best age.A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both models.However,after applying acceptance criteria to include only the most precise analyses with minimal discordance,a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the1000 Ma cutoff point.Because of the excessive rejection rate for Model-2,we select Model-1 as the preferred model.After eliminating all rejected samples,the remaining analyses use only Model-1 ages for five rock-type subsets of the database:igneous,meta-igneous,sedimentary,meta-sedimentary,and modern sediments.Next,time-series plots,cross-correlation analyses,and spectral analyses determine the degree of alignment among the time-series and their periodicity.For all rock types,the U-Pb age distributions are similar for ages older than 500 Ma,but align poorly for ages younger than 500 Ma.The similarities(>500 Ma)and differences(<500 Ma)highlight how reductionism from a detailed database enhances understanding of time-dependent sequences,such as erosion,detrital transport mechanisms,lithification,and metamorphism.Time-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of^91-Myr,~273-Myr,and^819-Myr among the various rock types.展开更多
In resectable colorectal liver metastasis(CRLM) the role and use of molecular biomarkers is still controversial. Several biomarkers have been linked to clinical outcomes in CRLM, but none have so far become routine fo...In resectable colorectal liver metastasis(CRLM) the role and use of molecular biomarkers is still controversial. Several biomarkers have been linked to clinical outcomes in CRLM, but none have so far become routine for clinical decision making. For several reasons, the clinical risk score appears to no longer hold the same predictive value. Some of the reasons include the ever expanding indications for liver resection, which now increasingly tend to involve extrahepatic disease, such as lung metastases(both resectable and non-resectable) and the shift in indication from "what is taken out"(e.g., how much liver has to be resected) to "what is left behind"(that is, how much functional liver tissue the patient has after resection). The latter is amenable to modifications by using adjunct techniques of portal vein embolization and the associating liver partition and portal vein ligation for staged hepatectomy techniques to expand indications for liver resection. Added to this complexity is the increasing number of molecular markers, which appear to hold important prognostic and predictive information, for which some will be discussed here. Beyond characteristics of tissue-based genomic profiles will be liquid biopsies derived from circulating tumor cells and cell-free circulating tumor DNA in the blood. These markers are present in the peripheral circulation in the majority of patients with metastatic cancer disease. Circulating biomarkers may represent more readily available methods to monitor, characterize and predict cancer biology with future implications for cancer care.展开更多
Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the...Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.展开更多
The Cloud is increasingly being used to store and process big data for its tenants and classical security mechanisms using encryption are neither sufficiently efficient nor suited to the task of protecting big data in...The Cloud is increasingly being used to store and process big data for its tenants and classical security mechanisms using encryption are neither sufficiently efficient nor suited to the task of protecting big data in the Cloud.In this paper,we present an alternative approach which divides big data into sequenced parts and stores them among multiple Cloud storage service providers.Instead of protecting the big data itself,the proposed scheme protects the mapping of the various data elements to each provider using a trapdoor function.Analysis,comparison and simulation prove that the proposed scheme is efficient and secure for the big data of Cloud tenants.展开更多
The main contribution of this paper is the design of an event-triggered formation control for leader-following consensus in second-order multi-agent systems(MASs)under communication faults.All the agents must follow t...The main contribution of this paper is the design of an event-triggered formation control for leader-following consensus in second-order multi-agent systems(MASs)under communication faults.All the agents must follow the trajectories of a virtual leader despite communication faults considered as smooth time-varying delays dependent on the distance between the agents.Linear matrix inequalities(LMIs)-based conditions are obtained to synthesize a controller gain that guarantees stability of the synchronization error.Based on the closed-loop system,an event-triggered mechanism is designed to reduce the control law update and information exchange in order to reduce energy consumption.The proposed approach is implemented in a real platform of a fleet of unmanned aerial vehicles(UAVs)under communication faults.A comparison between a state-of-the-art technique and the proposed technique has been provided,demonstrating the performance improvement brought by the proposed approach.展开更多
This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are re...This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.展开更多
Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperat...Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk.展开更多
An increasing number of patients are being referred to pancreatic centres around the world due to often incidentally discovered cystic neoplasms of the pancreas.The evaluation and management of pancreatic cystic neopl...An increasing number of patients are being referred to pancreatic centres around the world due to often incidentally discovered cystic neoplasms of the pancreas.The evaluation and management of pancreatic cystic neoplasms is a controversial topic and with existing guidelines based on a lack of strong evidence there is discordance between centres and guidelines with regard to when to offer surgery and when to favour surveillance.The frequency,duration and modality of surveillance is also controversial as this is resource-consuming and must be balanced against the perceived benefits and risks involved.While there is consensus that the risk of malignancy should be balanced against the lifeexpectancy and comorbidities,the indications for surgery and surveillance strategies vary among the guidelines.Thus,the tug of war between surveillance or resection continues.Here we discuss the recommendations from guidelines with further accumulating data and emerging reports on intraductal papillary mucinous neoplasm in the literature.展开更多
We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-...We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-off test data were used to construct a mathematical model, which was in turn applied to finding the inverse of an overdetermined system of equations.The method has been demonstrated by a case study in the Appalachian Basin, USA. The calculated horizontal stresses are in reasonable agreement with the reported regional stress study of the area, although there are no field measurement data of the studied well for direct calibration. The results also indicate that 2% of axis difference in the elliptical borehole geometry can cause a 5% difference in minimum horizontal stress calculation and a 10% difference in maximum horizontal stress calculation.展开更多
文摘Solid-state batteries have recently raised strong interest in the scientific community as possible advancement of battery technology beyond commercial lithium ion due to the promise of high energy densities and improved safety[1].In the core of development of high-performance solid-state batteries,is the development of solid-state electrolytes,which should be both sufficiently ionically conductive and offer stable interphases with high-energy electrodes,such as alkali metals and silicon[2,3].Recently,potassium-ion batteries have emerged as an alternative to lithium-ion batteries as a remedy to limited resources and uneven distribution of lithium,as well as due to the fact that low standard electrode potentials of K/K^(+) electrodes should lead to high operation voltages,competitive to those observed in commercial lithium batteries[4-6].
文摘Hydrogen is recognized as a clean energy carrier that can decarbonize heavy industry and the aviation system.However,the infrastructure is not yet ready for a hydrogen economy and large-scale hydrogen storage is needed to balance the mismatch between supply and demand.Therefore,depleted gas fields have been proposed as suitable storage sites,given the presence of infrastructure and pipeline network for distribution and utilization.Attempts have been made to analyze the suitability of these reservoirs for hydrogen storage,with a focus on choosing higher temperature and salinity conditions to neutralize the effects of microbial activities as one of the main sources of hydrogen loss in the depleted gas reservoirs.However,thermochemical sulfate reduction(TSR)is activated at high temperatures and has a huge potential not only to consume hydrogen through abiotic reactions but also to generate a huge amount of H_(2)S.In this study,a onedimensional diffusion-based mass transport model was built using PHREEQC to highlight the potential challenges posed by the TSR in depleted gas fields.The results obtained indicated that the presence of iron minerals(pyrite and hematite)is crucial for H_(2)S generation through TSR reactions.An increase in temperature also leads to an increase in H_(2)S concentration in the brine and gas phase.However,since most of the H_(2)S formation comes from pyrite dissolution and pyrite dissolution is still strong at lower temperatures,a low temperature is not necessarily the best selection criterion to avoid H_(2)S formation.Thus,precautions must be taken to ensure that activation of TSR does not pose significant environmental problems.
文摘This article provides a method by which the scour depth and scour width below pipelines,and the scour depth around single vertical piles as well as the time scales of scour for both structures due to bichromatic and bidirectional waves are calculated.The scour and time scale formulae summarized by Sumer and Fredsøe(2002)as well as the bottom shear stress formulae under bichromatic and bidirectional waves by Myrhaug et al.(2023)are used.Results for unidirectional bichromatic waves and symmetrically bidirectional monochromatic waves are provided,showing qualitative agreement with what is expected physically.Qualitative comparisons are made with the data from Schendel et al.’s(2020)small scale laboratory tests on scour around a monopile induced by directionally spread waves.Applications to related cases for pipelines are also suggested.In order to conclude regarding the validity of the method for pipelines and vertical piles,it is required to compare with data in its validity range.
基金The article is a result of joined research performed during the project:“A Floating Dock Digital Twin towards Efficient,Safer and Autonomous Docking Operations”-NOR/POLNOR/DigiFloDock/0009/2019-00 which is cofinanced by the programme“Applied research”under the Norwegian Financial Mechanisms 2014-2021 POLNOR 2019-Digital and Industry.
文摘During normal de-ballasting operations for floating docks,each ballast pump independently manages a specific group of ballast tanks.However,when a pump malfunctions,a connection valve between the two groups of ballast water systems is opened.This allows the adjacent pump to serve as a helper pump,simultaneously controlling two groups of ballast water systems.This study explores a full-scale floating dock’s dynamic behaviours during the de-ballasting operations under this situation through a numerical model.In the developed numerical model,the dock is described as a six-degree-of-freedom rigid body which is subjected to hydrostatic,hydrodynamic,and mooring loads.A hydraulic model of the piping network of the malfunctioning pump and the helper pump is proposed.A modified P-controller regulates opening angles of all tank valves for minimal pitch and roll.Two configurations of the floating dock,i.e.,a single floating dock and a floating dock with an onboard vessel,are considered.The numerical results show that the optimal helper pumps can be identified regarding the pumps’total de-ballasting capacity and the dock’s stability.The most severe scenarios can be determined in term of the dock’s maximum draught differences caused by its roll and pitch.The observed maximum draught differences remain small relative to the dock’s width,indicating the effectiveness of employing helper pumps and the proposed automatic ballast control strategy for one-pump malfunction scenarios.
基金support of the National Natural Science Foundation of China(Grant Nos.52174030,52474042 and 52374041)the Postgraduate Innovation Fund Project of Xi'an Shiyou University(No.YCX2411001)the Natural Science Basic Research Program of Shaanxi(Program Nos.2024JCYBMS-256 and 2022JQ-528)。
文摘Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehensive physical simulation experiments were conducted under varied pressures,coupled with assessments of changes in mineral composition,ion concentrations,pore morphology,permeability,and sequestration capacity before and after experimentation.Simultaneously,a method using NMR T2spectra changes to measure pore volume shift and estimate CO_(2)sequestration is introduced.It quantifies CO_(2)needed for mineralization of soluble minerals.However,when CO_(2)dissolves in crude oil,the precipitation of asphaltene compounds impairs both seepage and storage capacities.Notably,the impact of dissolution and precipitation is closely associated with storage pressure,with a particularly pronounced influence on smaller pores.As pressure levels rise,the magnitude of pore alterations progressively increases.At a pressure threshold of 25 MPa,the rate of change in small pores due to dissolution reaches a maximum of 39.14%,while precipitation results in a change rate of-58.05%for small pores.The observed formation of dissolution pores and micro-cracks during dissolution,coupled with asphaltene precipitation,provides crucial insights for establishing CO_(2)sequestration parameters and optimizing strategies in low permeability reservoirs.
文摘AIM:To investigate the epidemiological trends in inci-dence and mortality of perforated peptic ulcer(PPU)in a well-defined Norwegian population. METHODS:A retrospective,population-based,single-center,consecutive cohort study of all patients diag-nosed with benign perforated peptic ulcer.Included were both gastric and duodenal ulcer patients admitted to Stavanger University Hospital between January 2001 and December 2010.Ulcers with a malignant neoplasia diagnosis,verified by histology after biopsy or resection,were excluded.Patients were identified from the hospitals administrative electronic database using pertinent ICD-9 and ICD-10 codes(K25.1,K25.2,K25.5, K25.6,K26.1,K26.2,K26.5,K26.6).Additional searches using appropriate codes for relevant laparoscopic and open surgical procedures(e.g.,JDA 60,JDA 61,JDH 70 and JDH 71)were performed to enable a complete identification of all patients.Patient demographics,presentation patterns and clinical data were retrieved from hospital records and surgical notes.Crude and adjusted incidence and mortality rates were estimated by using national population demographics data. RESULTS:In the study period,a total of 172 patients with PPU were identified.The adjusted incidence rate for the overall 10-year period was 6.5 per 100 000 per year(95%CI:5.6-7.6)and the adjusted mortality rate for the overall 10-year period was 1.1 per 100 000 per year(95%CI:0.7-1.6).A non-significant decline in ad-justed incidence rate from 9.7 to 5.6 occurred during the decade.The standardized mortality ratio for the whole study period was 5.7(95%CI:3.9-8.2),while the total 30-d mortality was 16.3%.No difference in in-cidence or mortality was found between genders.However,for patients≥60 years,the incidence increased over 10-fold,and mortality more than 50-fold,compared to younger ages.The admission rates outside office hours were high with almost two out of three(63%) admissions seen at evening/night time shifts and/or during weekends.The observed seasonal variations in admissions were not statistically significant. CONCLUSION:The adjusted incidence rate,seasonal distribution and mortality rate was stable.PPU fre-quently presents outside regular work-hours.Increase in incidence and mortality occurs with older age.
文摘The method of obtaining zircon samples affects estimation of the global U-Pb age distribution.Researchers typically collect zircons via convenience sampling and cluster sampling.When using these techniques,weight adjustments proportional to the areas of the sampled regions improve upon unweighted estimates.Here,grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb ages.Preliminary tests involve two age models.Model-1 uses the most precise U-Pb ages as the best ages.Model-2 uses the^(206)Pb/^(238)U age as the best age if it is less than a1000 Ma cutoff,otherwise it uses the^(207)Pb/^(206)Pb age as the best age.A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both models.However,after applying acceptance criteria to include only the most precise analyses with minimal discordance,a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the1000 Ma cutoff point.Because of the excessive rejection rate for Model-2,we select Model-1 as the preferred model.After eliminating all rejected samples,the remaining analyses use only Model-1 ages for five rock-type subsets of the database:igneous,meta-igneous,sedimentary,meta-sedimentary,and modern sediments.Next,time-series plots,cross-correlation analyses,and spectral analyses determine the degree of alignment among the time-series and their periodicity.For all rock types,the U-Pb age distributions are similar for ages older than 500 Ma,but align poorly for ages younger than 500 Ma.The similarities(>500 Ma)and differences(<500 Ma)highlight how reductionism from a detailed database enhances understanding of time-dependent sequences,such as erosion,detrital transport mechanisms,lithification,and metamorphism.Time-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of^91-Myr,~273-Myr,and^819-Myr among the various rock types.
文摘In resectable colorectal liver metastasis(CRLM) the role and use of molecular biomarkers is still controversial. Several biomarkers have been linked to clinical outcomes in CRLM, but none have so far become routine for clinical decision making. For several reasons, the clinical risk score appears to no longer hold the same predictive value. Some of the reasons include the ever expanding indications for liver resection, which now increasingly tend to involve extrahepatic disease, such as lung metastases(both resectable and non-resectable) and the shift in indication from "what is taken out"(e.g., how much liver has to be resected) to "what is left behind"(that is, how much functional liver tissue the patient has after resection). The latter is amenable to modifications by using adjunct techniques of portal vein embolization and the associating liver partition and portal vein ligation for staged hepatectomy techniques to expand indications for liver resection. Added to this complexity is the increasing number of molecular markers, which appear to hold important prognostic and predictive information, for which some will be discussed here. Beyond characteristics of tissue-based genomic profiles will be liquid biopsies derived from circulating tumor cells and cell-free circulating tumor DNA in the blood. These markers are present in the peripheral circulation in the majority of patients with metastatic cancer disease. Circulating biomarkers may represent more readily available methods to monitor, characterize and predict cancer biology with future implications for cancer care.
文摘Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.
基金supported in part by the National Nature Science Foundation of China under Grant No.61402413 and 61340058 the "Six Kinds Peak Talents Plan" project of Jiangsu Province under Grant No.ll-JY-009+2 种基金the Nature Science Foundation of Zhejiang Province under Grant No.LY14F020019, Z14F020006 and Y1101183the China Postdoctoral Science Foundation funded project under Grant No.2012M511732Jiangsu Province Postdoctoral Science Foundation funded project Grant No.1102014C
文摘The Cloud is increasingly being used to store and process big data for its tenants and classical security mechanisms using encryption are neither sufficiently efficient nor suited to the task of protecting big data in the Cloud.In this paper,we present an alternative approach which divides big data into sequenced parts and stores them among multiple Cloud storage service providers.Instead of protecting the big data itself,the proposed scheme protects the mapping of the various data elements to each provider using a trapdoor function.Analysis,comparison and simulation prove that the proposed scheme is efficient and secure for the big data of Cloud tenants.
文摘The main contribution of this paper is the design of an event-triggered formation control for leader-following consensus in second-order multi-agent systems(MASs)under communication faults.All the agents must follow the trajectories of a virtual leader despite communication faults considered as smooth time-varying delays dependent on the distance between the agents.Linear matrix inequalities(LMIs)-based conditions are obtained to synthesize a controller gain that guarantees stability of the synchronization error.Based on the closed-loop system,an event-triggered mechanism is designed to reduce the control law update and information exchange in order to reduce energy consumption.The proposed approach is implemented in a real platform of a fleet of unmanned aerial vehicles(UAVs)under communication faults.A comparison between a state-of-the-art technique and the proposed technique has been provided,demonstrating the performance improvement brought by the proposed approach.
文摘This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.
文摘Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk.
文摘An increasing number of patients are being referred to pancreatic centres around the world due to often incidentally discovered cystic neoplasms of the pancreas.The evaluation and management of pancreatic cystic neoplasms is a controversial topic and with existing guidelines based on a lack of strong evidence there is discordance between centres and guidelines with regard to when to offer surgery and when to favour surveillance.The frequency,duration and modality of surveillance is also controversial as this is resource-consuming and must be balanced against the perceived benefits and risks involved.While there is consensus that the risk of malignancy should be balanced against the lifeexpectancy and comorbidities,the indications for surgery and surveillance strategies vary among the guidelines.Thus,the tug of war between surveillance or resection continues.Here we discuss the recommendations from guidelines with further accumulating data and emerging reports on intraductal papillary mucinous neoplasm in the literature.
基金support of the United States Department of Energy (DE-FE0026825, UCFER-University Coalition for Fossil Energy Research)
文摘We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-off test data were used to construct a mathematical model, which was in turn applied to finding the inverse of an overdetermined system of equations.The method has been demonstrated by a case study in the Appalachian Basin, USA. The calculated horizontal stresses are in reasonable agreement with the reported regional stress study of the area, although there are no field measurement data of the studied well for direct calibration. The results also indicate that 2% of axis difference in the elliptical borehole geometry can cause a 5% difference in minimum horizontal stress calculation and a 10% difference in maximum horizontal stress calculation.
