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Research trend of cascade heat pumps

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Science China(Technological Sciences) 2017年第11期60卷 1597-1615页

作者： BOAHEN samuel CHOI JongMin graduate School of Mechanical Engineering Hanbat National UniversityDaejeon 34158Korea Department of Mechanical Engineering Hanbat National UniversityDaejeon 34158Korea

Most commercial and industrial facilities require very low temperatures for refrigeration and high temperatures for space heating and hot water purposes. Single stage heat pumps have not been able to meet these temperature demands and have been characterized by low capacities and coefficient of performance(COP). Cascade heat pump has been developed to overcome the weaknesses of single stage heat pumps. This study reviews recent works done by researchers on cascade heat pumps for refrigeration, heating and hot water generation. Selection of suitable refrigerants to meet the pressure and temperature demands of each stage of the cascade heat pump has been discussed. Optimization of design parameters such as intermediate temperature(low stage condensing and high stage evaporating temperatures), and temperature difference in the cascade heat exchanger for optimum performance of the cascade heat pump has been reviewed. It was found that optimising each design parameter of the cascade heat pump is necessary for maximum system performance and this may improve the exergetic efficiency, especially of cascade refrigeration systems, by about 30.88%. Cascade heat pumps have wider range of application especially for artificial snow production, in the supermarkets,for natural gas liquefaction, in drying clothes and food and as heat recovery system. The performance of cascade heat pumps can be improved by 19% when coupled with other renewable energy sources for various real time applications. Also, there is the need for much research on refrigerant charge amount of cascade heat pumps, refrigerant-refrigerant heat exchangers to be used as cascade heat exchanger, cascade heat pumps for simultaneous cooling, heating and hot water generation and on the use of variable speed compressors and their control strategies in matching system capacity especially at part load conditions.

关键词： cascade heat pump low stage high stage optimization system performance refrigerant

Impulse force reductions and their effects on WBV exposures in high impact shovel loading operations

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International Journal of Mining Science and Technology 2018年第3期28卷 423-435页

作者： Danish Ali samuel Frimpong Mining & Nuclear Engineering Department Missouri University of Science and Technology

When shovels load the dump trucks with over 100-ton passes under gravity dumping conditions, they will create a large impact force on the dump truck body which generates high frequency shock waves which expose the operators to whole body vibrations （WBV）. The main cause of such truck vibrations is the large impact force due to the gravity dumping of large tonnage passes. Therefore a rigorous mathematical model has been developed for the impact force containing all the necessary factors upon which it depends. Latter, a thorough analysis shows that percentage reduction of 7.19%, 9.40%, 13.27%, 14.8%, 17.30% and 18.13% can he achieved by reducing the dumping distance to 6.33 m, 6.0 m, 5.5 m, 5.33 m, 5.0 m and 4.9 m, respectively, as compared to when the dumping distance was 7.33 m. Even more reduction in the magnitude of impact force can he observed if the shovel pass gets divided into more than two sub-passes. Therefore, these models can he used to figure out the number of sub-passes into which a single ore pass can he divided and/or the extent to which the dumping distance can he reduced which would reduce the impact force significantly enough to obtain safer yet economic operations.

关键词： Impact force HISLO Mathematical modeling Dumping distance Shovel ore sub-passes

Isolation, characterization and modulatory potentials of β-stigmasterol, ergosterol and xylopic acid from Anchomanes difformis on mitochondrial permeability transition pore in vitro

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Chinese Herbal Medicines 2023年第4期15卷 533-541页

作者： kehinde Oluseun Sodeinde Akinwunmi Oluwaseun Adeoye Adedeji Adesipo Adebayo AAdeniyi John Adeolu Falode Tajudeen Olabisi Obafemi samuel Olalekan Olusanya Linette Twigge Jeanet Conradie Timothy O.Mosaku Department of Chemistry Federal University Oye-EkitiEkiti State 371104Nigeria Biomembrane Toxicology and Drug Discovery UnitDepartment of BiochemistryFederal University Oye-EkitiEkiti State 371104Nigeria Department of Biochemistry Afe Babalola UniversityAdo-EkitiEkiti State 360001Nigeria Department of Chemistry University of Free StateBloemfontein 9301South Africa Department of Civil Engineering Covenant UniversityOgun State 112104Nigeria

Objective: Secondary metabolites and polyphenolic compounds from medicinal plants have been demonstrated to have multiple biological functions with promising research and development prospects. This study examined the effect of β-stigmasterol(with ergosterol) and xylopic acid isolated from Anchomanes difformis on liver mitochondrial permeability transition pore(mPTP).Methods: The compounds were isolated by vacuum liquid chromatography. Mitochondrial swelling was assessed as changes in absorbance under succinate-energized ***:1H and13C NMR spectroscopic elucidation of the isolates affirmed the presence of β-stigmasterol with ergosterol(1:0.3) and xylopic acid. The isolates reversed the increase in lipid peroxidation and inhibited the opening of mitochondrial permeability transition pores caused by calcium and *** inhibition of m PTP offers a promising therapeutic target for the treatment of mitochondrial-associated ***: Reduction in the activity of calcium ATPase and the expression of Caspase-3 and-9 were observed, suggesting that they could play a role in protecting physicochemical properties of membrane bilayers from free radical-induced severe cellular damage and be useful in the management of diseases where much apoptosis occurs.

关键词： Anchomanes difformis(Blume)Engl ergosterol mitochondrial membrane modulation β-stigmasterol transition pore xylopic acid

Incidences and Risk Factors for Surgical Site Infections in Koutiala, Mali

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Surgical Science 2024年第7期15卷 465-469页

作者： Mahamadou Coulibaly Moussa Diassana Issiaka Diarra Bréhima Bengaly Birama Togola Drissa Ouattara Souleymane Sanogo samuel Kletigui Dembélé Cheick Aka Waigalo Brehima Ballo Drissa Traoré Nouhoum Ongoiba Faculty of Medicine University of Science Technique and Technologies of Bamako Bamako Mali Department of Surgery Koutiala Hospital Koutiala Mali Department of Surgery Sikasso Hospital Sikasso Mali Dpartement de Chirurgie Hpital Commune I Bamako Mali Department of Surgery University Hospital Center Point G Bamako Mali Department of Surgery Tominian Hospital Tominian Mali

Purpose: This paper aims to assess the incidences and risk factors for surgical site (ISO) infections in the general surgery department of the Koutiala District Hospital. Patients and Methods: This was a prospective and descriptive study from August 1, 2017 to October 31, 2020 involving all patients who underwent laparotomy in the general surgery department of the Koutiala District Hospital. Patients who were not operated on and who did not have a laparotomy were not included. Age, sex, frequency, patient history, National Nosocomial Infections Surveillance (NNIS) index, time to occur, bacteriological test results and course of infection were analyzed. Results: Fifty patients were registered. The average age was 34.2 ± 21.2 years old. Eleven patients were 60 years old or older. The hospital incidence rate was 4.3% and the community incidence rate was 6.1 cases per 100,000 population. The concept of smoking was noted in 15 patients. Patients were operated on in emergency 84% of cases. Peritonitis was the most common initial lesion with 32% of cases. Our patients had an NNIS index greater than 0 in 84% of cases. The time to develop infection from the surgical site was less than 3 days in 8 patients (16% of cases). Depending on the depth of the infection, it was superficial (cutaneous) in 39 patients (78%) and deep (subcutaneous and organic) in 11 patients (22%). Escherichia coli was the most common germ with 72% followed by staphylococcus aureus at 24%. We noted 22% morbidity. The median length of hospitalization was 9 ± 2.2 days. Conclusion: ISO is common in our service. Prevention and mastery require knowledge of risk factors.

关键词： Surgical Site Infection Incidence Risk Factors Surgery

Multiclass stand-alone and ensemble machine learning algorithms utilised to classify soils based on their physico-chemical characteristics

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Journal of Rock Mechanics and geotechnical Engineering 2022年第2期14卷 603-615页

作者： Eyo Eyo samuel Abbey Faculty of Environment and Technology Department of Geography and Environmental ManagementCivil Engineering ClusterUniversity of the West of EnglandBristolBS161QYUK Fugro gB Marine geotechnical Services Limited WallingfordOX109RBUK

This study has provided an approach to classify soil using machine *** elements of stand-alone machine learning algorithms(*** regression(LR)and artificial neural network(ANN)),decision tree ensembles(*** forest(DF)and decision jungle(DJ)),and meta-ensemble models(*** ensemble(SE)and voting ensemble(VE))were used to classify soils based on their intrinsic physico-chemical ***,the multiclass prediction was carried out across multiple cross-validation(CV)methods,*** validation split(TVS),k-fold cross-validation(KFCV),and Monte Carlo cross-validation(MCCV).Results indicated that the soils’clay fraction(CF)had the most influence on the multiclass prediction of natural soils’plasticity while specific surface and carbonate content(CC)possessed the least within the nature of the dataset used in this ***-alone machine learning models(LR and ANN)produced relatively less accurate predictive performance(accuracy of 0.45,average precision of 0.5,and average recall of 0.44)compared to tree-based models(accuracy of 0.68,average precision of 0.71,and recall rate of 0.68),while the meta-ensembles(SE and VE)outperformed(accuracy of 0.75,average precision of 0.74,and average recall rate of 0.72)all the models utilised for multiclass *** analysis of the meta-ensembles proved their capacities to discriminate between soil classes across the methods of CV *** learning training and validation using MCCV and KFCV methods enabled better prediction while also ensuring that the dataset was not overfitted by the machine learning *** confirmation of this phenomenon was depicted by the continuous rise of the cumulative lift curve(LC)of the best performing models when using the MCCV ***,this study demonstrated that soil’s physico-chemical properties do have a direct influence on plastic behaviour and,therefore,can be relied upon to classify soils.

关键词： Soil classification Physico-chemistry Soil plasticity Machine learning Logistic regression(LR) Machine learning ensembles Artificial neural network(ANN)

Single-model uncertainty quantification in neural network potentials does not consistently outperform model ensembles

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npj Computational Materials 2023年第1期9卷 49-59页

作者： Aik Rui Tan Shingo Urata samuel goldman Johannes C.B.Dietschreit Rafael gómez-Bombarelli Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMAUSA Innovative Technology Laboratories AGC IncTokyoJapan Computational and Systems Biology Massachusetts Institute of TechnologyCambridgeMAUSA

Neural networks(NNs)often assign high confidence to their predictions,even for points far out of distribution,making uncertainty quantification(UQ)a *** they are employed to model interatomic potentials in materials systems,this problem leads to unphysical structures that disrupt simulations,or to biased statistics and dynamics that do not reflect the true *** UQ techniques can find new informative data and drive active learning loops for robust ***,a variety of UQ techniques,including newly developed ones,exist for atomistic simulations and there are no clear guidelines for which are most effective or suitable for a given *** this work,we examine multiple UQ schemes for improving the robustness of NN interatomic potentials(NNIPs)through active *** particular,we compare incumbent ensemble-based methods against strategies that use single,deterministic NNs:mean-variance estimation(MVE),deep evidential regression,and gaussian mixture models(gMM).We explore three datasets ranging from in-domain interpolative learning to more extrapolative out-of-domain generalization challenges:rMD17,ammonia inversion,and bulk silica *** is measured across multiple metrics relating model error to *** experiments show that none of the methods consistently outperformed each other across the various *** remained better at generalization and for NNIP robustness;MVE only proved effective for in-domain interpolation,while gMM was better out-of-domain;and evidential regression,despite its promise,was not the preferable alternative in any of the *** broadly,cost-effective,single deterministic models cannot yet consistently match or outperform ensembling for uncertainty quantification in NNIPs.

关键词： ensemble evident neural

Immune pathway through endometriosis to ovarian cancer

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World Journal of Clinical Oncology 2024年第4期15卷 496-522页

作者： Mariana Santos Calmon Fabian Fellipe Bueno Lemos Marcel Silva Luz samuel Luca Rocha Pinheiro Luis guilherme de Oliveira Silva gabriel Lima Correa Santos gabriel Reis Rocha Fabrício Freire de Melo Instituto Multidisciplinar em Saúde Universidade Federal da BahiaVitória da Conquista 45029-094BahiaBrazil

Endometriosis is an estrogen-dependent inflammatory disease,defined by the presence of functional endometrial tissue outside of the uterine *** disease is one of the main gynecological diseases,affecting around 10%-15%women and girls of reproductive age,being a common gynecologic *** endometriosis is a benign disease,it shares several characteristics with invasive *** support that it has been linked with an increased chance of developing endometrial ovarian cancer,representing an earlier stage of neoplastic *** is particularly true for women with clear cell carcinoma,low-grade serous carcinoma and ***,the carcinogenic pathways between both pathologies remain poorly *** studies suggest a connection between endometriosis and endometriosis-associated ovarian cancers(EAOCs)via pathways associated with oxidative stress,inflammation,and *** article aims to review current data on the molecular events linked to the development of EAOCs from endometriosis,specifically focusing on the complex relationship between the immune response to endometriosis and cancer,including the molecular mechanisms and their *** recent developments in immunotherapy and their potential to boost the effectiveness of future treatments.

关键词： Ovarian neoplasms Endometriosis Endometriosis-associated ovarian cancers Immune response Immunotherapy

Statin, aspirin and metformin use and risk of hepatocellular carcinoma related outcomes following liver transplantation: A retrospective study

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World Journal of Transplantation 2024年第3期14卷 120-131页

作者： William Chung Kevin Wong Noel Ravindranayagam Lauren Tang Josephine grace Darren Wong Danny Con Marie Sinclair Avik Majumdar Numan Kutaiba samuel Hui Paul gow Vijayaragavan Muralidharan Alexander Dobrovic Adam Testro Department of gastroenterology Austin HealthHeidelberg 3084VictoriaAustralia Victorian Liver Transplant Unit Austin HealthHeidelberg 3084VictoriaAustralia Department of Radiology Austin HealthHeidelberg 3084VictoriaAustralia Department of gastroenterology Monash HealthClayton 3168VictoriaAustralia Department of Surgery University of MelbourneAustin HealthHeidelberg 3048VictoriaAustralia Department of Surgery Beacon LaboratoryAustin PrecinctThe University of MelbourneAustin HospitalHeidelberg 3048VictoriaAustralia

BACKgROUND Liver transplantation(LT)is a potentially curative therapy for patients with hepatocellular carcinoma(HCC).HCC-recurrence following LT is associated with reduced *** is increasing interest in chemoprophylaxis to improve HCC-related outcomes *** To investigate whether there is any benefit for the use of drugs with proposed chemoprophylactic properties against HCC,and patient outcomes following *** This was a retrospective study of adult patients who received Deceased Donor LT for HCC from 2005-2022,from a single Australian *** use was defined as statin,aspirin or metformin therapy for≥29 days,within 24 months post-LT.A cox proportional-hazards model with time-dependent covariates was used for survival *** measures were the composite-endpoint of HCC-recurrence and all-cause mortality,HCC-recurrence and HCC-related *** analysis was performed to account for immortality time bias and statin *** Three hundred and five patients were included in this study,with 253(82.95%)males with a median age of 58.90 *** of liver disease were 150(49.18%)hepatitis C,73(23.93%)hepatitis B(HBV)and 33(10.82%)non-alcoholic fatty liver disease(NAFLD).56(18.36%)took statins,51(16.72%)aspirin and 50(16.39%)*** a median follow-up time of 59.90 months,34(11.15%)developed HCC-recurrence,48(15.74%)died,17(5.57%)from HCC-related ***,aspirin or metformin use was not associated with statistically significant differences in the composite endpoint of HCC-recurrence or all-cause mortality[hazard ratio(HR):1.16,95%CI:0.58-2.30;HR:1.21,95%CI:0.28-5.27;HR:0.61,95%CI:0.27-1.36],HCC-recurrence(HR:0.52,95%CI:0.20-1.35;HR:0.51,95%CI:0.14-1.93;HR 1.00,95%CI:0.37-2.72),or HCC-related mortality(HR:0.32,95%CI:0.033-3.09;HR:0.71,95%CI:0.14-3.73;HR:1.57,95%CI:0.61-4.04)*** dosing was not associated with statist-ically significant differences in HCC-related ***

关键词： Liver transplantation Hepatocellular carcinoma Transplant oncology Statins HMg-Co-A reductase Aspirin Metformin Mammalian target of rapamycin

Inspection of free energy functions in gradient crystal plasticity

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Acta Mechanica Sinica 2013年第6期29卷 763-772页

作者： samuel Forest Nicolas guninchault Centre des Matriaux Mines ParisTechCNRS UMR 7633 BP 8791003 Evry CedexFrance

The dislocation density tensor computed as the cud of plastic distortion is regarded as a new constitutive variable in crystal plasticity. The dependence of the free energy function on the dislocation density tensor is explored starting from a quadratic ansatz. Rank one and logarithmic dependencies are then envisaged based on considerations from the statistical theory of dislocations. The rele- vance of the presented free energy potentials is evaluated from the corresponding analytical solutions of the periodic two-phase laminate problem under shear where one layer is a single crystal material undergoing single slip and the second one remains purely elastic.

关键词： gradient plasticity Crystal plasticity Continuum thermodynamics Dislocation density tensor Read- Shockley energy