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Improving surface integrity when drilling CFRPs and Ti-6Al-4V using sustainable lubricated liquid carbon dioxide

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Chinese Journal of Aeronautics 2023年第7期36卷 129-146页

作者： In˜igo RODRIGUEZ Pedro Jose´ARRAZOLA Mikel CUESTA Luka STERLE Franci PUSˇAVEC Faculty of Engineering Mondragon UnibertsitateaArrasate-Mondragon 20500Spain Faculty of Mechanical Engineering University of LjubljanaLjubljana 1000Slovenia

In the quest for decreasing fuel consumption and resulting gas emissions in the aeronautic sector,lightweight materials such as Carbon Fiber Reinforced Polymers(CFRPs)and Ti-6Al-4V alloys are being used.These materials,with excellent weight-to-strength ratios,are widely used for structural applications in aircraft manufacturing.To date,several studies have been published showing that the use of metalworking fluids(MWFs),special tool geometries,or advanced machining techniques is required to ensure a surface quality that meets aerospace component standards.Conventional MWFs pose a number of environmental and worker health hazards and also degrade the mechanical properties of CFRPs due to water absorption in the composite.Therefore,a transition to more environmentally friendly cooling/lubrication techniques that prevent moisture problems in the composite is needed.This research shows that lubricated LCO_(2) is a viable option to improve the quality of drilled CFRP and titanium aerospace components compared to dry machining,while maintaining clean work areas.The results show that the best combination of tool geometry and cooling conditions for machining both materials is drilling with Brad point drills and lubricated LCO_(2).Drilling under these conditions resulted in a 90%improvement in fiber pullout volume compared to dry machined CFRP holes.In addition,a 33% reduction in burr height and a 15% improvement in surface roughness were observed compared to dry drilling of titanium.

关键词： Carbon fibers Cryogenics Green manufacturing Machining Solid lubricants Surface morphology Titanium alloys

Development and validation of the scale for measuring biopsychosocial approach of family physicians to their patients

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Family Medicine and Community Health 2022年第2期10卷 26-31页

作者： Irena Makivić Zalika Klemenc-Ketiš National Institute of Public Health LjubljanaSlovenia Department of Family Medicine University of Ljubljana Faculty of MedicineLjubljanaSlovenia Department of Family Medicine Faculty of Medicine University of MariborMariborSlovenia

Objective While other models focus more on disease and pathophysiology,the biopsychosocial approach emphasises the importance of human health and disease in their fullest contexts.If we are to gain an insight into physical and psychological health needs,and address them quickly and adequately,it is important that we recognise them already at the family practice stage.An approach that assesses needs at patient level could also be seen as patient-centred care,which is one of the key elements of high-quality care.To the best of our knowledge,no scale for measuring the biopsychosocial approach of family physicians has yet been developed.Design The aim of this study was to develop and validate a scale that measures the biopsychosocial approach of family physicians to their patients through the Delphi and validation process.Setting The scale was developed through the Delphi study and validated by means of significant statistical methods.Pearson’s correlation coefficient,Cronbach’s alpha,the intracorrelation coefficient,the Spearman-Brown coefficient and exploratory factor analysis were applied.Participants Five family physicians took part in a brainstorming process and 24 family medicine experts took part in the Delphi study.For the first part of the validation process,there were 31 family medicine trainees in the first group and 32 in the second group.For the last part of the validation process,164 family physicians completed the scale.Result Through the Delphi study,39 final items covering three areas within the biopsychosocial approach were identified.Construct validity was high,with positive linear correlation and good face validity.The intraclass correlation coefficient for test-retest reliability was 0.862.The Spearman-Brown coefficient was the highest(0.931)on an even and odd division.Factor rotation showed that three factors on 35 items explained 39.5%of variances.The final internal consistency on 35 items was 0.911.Conclusion The developed scale measures the biopsychosocial dimension of family physicians’work

关键词： approach validity measures

Magnetocontrollable droplet mobility on liquid crystal-infused porous surfaces

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Nano Research 2023年第4期16卷 5098-5107页

作者： Yang Xu Yuxing Yao Weichen Deng Jen-Chun Fang Robert LDupont Meng Zhang SimonČopar UrošTkalec Xiaoguang Wang William G.Lowrie Department of Chemical and Biomolecular Engineering The Ohio State UniversityColumbusOH 43210USA Division of Chemistry and Chemical Engineering California Institute of TechnologyPasadenaCA 91125USA Department of Physics Faculty of Mathematics and PhysicsUniversity of Ljubljana1000 LjubljanaSlovenia Institute of Biophysics Faculty of MedicineUniversity of Ljubljana1000 LjubljanaSlovenia Department of Physics Faculty of Natural Sciences and MathematicsUniversity of Maribor2000 MariborSlovenia Department of Condensed Matter Physics Jožef Stefan Institute1000 LjubljanaSlovenia Sustainability Institute The Ohio State UniversityColumbusOH 43210USA

Magnetocontrollable droplet mobility on surfaces of both solids and simple fluids have been widely used in a wide range of applications.However,little is understood about the effect of the magnetic field on the wettability and mobility of droplets on structured fluids.Here,we report the manipulation of the dynamic behaviors of water droplets on a film of thermotropic liquid crystals(LCs).We find that the static wetting behavior and static friction of water droplets on a 4’-octyl-4-biphenylcarbonitrile(8CB)film strongly depend on the LC mesophases,and that a magnetic field caused no measurable change to these properties.However,we find that the droplet dynamics can be affected by a magnetic field as it slides on a nematic 8CB film,but not on isotropic 8CB,and is dependent on both the direction and strength of the magnetic field.By measuring the dynamic friction of a droplet sliding on a nematic 8CB film,we find that a magnetic field alters the internal orientational ordering of the 8CB which in turn affects its viscosity.We support this interpretation with a scaling argument using the LC magnetic coherence length that includes(i)the elastic energy from the long-range orientational ordering of 8CB and(ii)the free energy from the interaction between 8CB and a magnetic field.Overall,these results advance our understanding of droplet mobility on LC films and enable new designs for responsive surfaces that can manipulate the mobility of water droplets.

关键词： liquid crystals lubricated surfaces magnetic field wettability droplet mobility

Problematics of neurosurgical service during the COVID-19 pandemic in Slovenia

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World Journal of Clinical Cases 2022年第34期10卷 12462-12469页

作者： Matic Munda Roman Bosnjak Tomaz Velnar Department of Neurosurgery University Medical Centre LjubljanaLjubljana 1000Slovenia Alma Mater Europaea AMEU-ECMMaribor 2000Slovenia

The novel coronavirus disease 2019(COVID-19)is an ongoing disease caused by severe acute respiratory syndrome coronavirus-2 that still poses an important and urgent threat to global health.In Slovenia,the epidemic was declared on March 12th,2020,and since then COVID-19 has had a great impact on our health system.The field of neurosurgery in particular has been experiencing difficulties in both elective and emergency service.In this article,we described epidemiologic protocols and the effect that the COVID-19 pandemic had on the surgical practice and workflow of the Department of Neurosurgery at the university Medical Centre ljubljana.We analyzed and compared the number of elective and emergency neurosurgical procedures in a 2-year period before and during the pandemic.We recorded a drop in cases mostly on account of elective procedures whilst emergency service remained relatively unaffected.

关键词： Neurosurgery COVID-19 Pandemic Epidemic measures Slovenia ljubljana

Curing Kinetics of Tannin and Lignin Biobased Adhesives Determined by DSC and ABES

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Journal of Renewable Materials 2022年第8期10卷 2117-2131页

作者： Jaša Saražin Ida Poljanšek Antonio Pizzi MilanŠernek university of ljubljana Biotechnical FacultyLjubljana1000Slovenia Universitéde Lorraine LERMAB-ENSTIB Epinal88000France

The curing process of two biobased adhesives:pine tanninhexamine(TH)and organosolv lignin non-isocyanate polyurethane(NIPU),suitable for interior nonstructural use,were compared with commercial urea-formaldehyde(UF)adhesive.Changes in chemical structure before and after the curing process were observed with Fouriertransform infrared spectroscopy(FTIR).The process of adhesive curing was monitored with differential scanning calorimetry(DSC)and the automated bonding evaluation system(ABES).Both DSC and ABES measurements confirmed UF as the fastest and NIPU as the slowest curing adhesive observed.Taking into account the ABES results,the optimal pressing parameters for the TH adhesive would be 4 min at 175℃,for the NIPU adhesive 7 min at 200℃and for the UF 1.5 min at 100℃.Strong linear correlation was observed between mechanical and chemical curing for the UF and NIPU adhesives,whereas lower correlation was observed for the TH adhesive.At all observed adhesives,the DSC measurements were underestimating the curing process determined by ABES in the first part and overestimating it at the end.The underestimation was the most evident with the TH adhesive and the less with the UF adhesive.When comparing the uncured and cured FTIR spectra of all three types of adhesives,a drastic decrease in the characteristic band of-OH groups at 3330–3400 cm^(−1)and an increase in the signal intensity at 2920 cm^(−1)of aliphatic-CH2-groups were observed.For the UF adhesive,the C=O stretching frequency has shifted from 1632 cm^(−1)for uncured to three different bands at 1766,1701,and 1655 cm^(−1)for cured UF.The sharp band for phenolic alcohols at 1236 cm^(−1)of C–O stretch and hydroxyl O–H functional group at 1009 cm^(−1)and at 684 cm^(−1)of uncured TH adhesive diminished during curing,which indicates that a crosslinking reaction occurs via-OH groups.The peak of the C=O group of urethane bridges at 1697 cm^(−1)for uncured NIPU shifted to lower wavenumber at 1633 cm^(−1)for cured NIPU.

关键词： Biobased adhesives curing kinetics tannin lignin ABES DSC FTIR

Predictive value of preoperative albumin-bilirubin score and other risk factors for short-term outcomes after open pancreatoduodenectomy

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世界临床病例杂志 2023年第26期11卷 6051-6065页

作者： Hana Zavrtanik Davide Cosola David Badovinac Benjamin Hadžialjević Gašper Horvat Danaja Plevel Selene Bogoni Paola Tarchi Nicolòde Manzini AlešTomažič Department of Abdominal Surgery University Medical Centre LjubljanaLjubljana 1000Slovenia Clinica Chirurgica Azienda Sanitaria Universitaria Giuliano IsontinaCattinara HospitalTrieste 34149Italy Department of Medical Surgical and Health SciencesUniversity of TriesteTrieste 34149Italy Faculty of Medicine University of LjubljanaLjubljana 1000Slovenia

BACKGROUND Pancreatoduodenectomy represents a complex procedure involving extensive organ resection and multiple alimentary reconstructions.It is still associated with high morbidity,even in high-volume centres.Prediction tools including preoperative patient-related factors to preoperatively identify patients at high risk for postoperative complications could enable tailored perioperative management and improve patient outcomes.AIM To evaluate the clinical significance of preoperative albumin-bilirubin score and other risk factors in relation to short-term postoperative outcomes in patients after open pancreatoduodenectomy.METHODS This retrospective study included all patients who underwent open pancreatic head resection(pylorus-preserving pancreatoduodenectomy or Whipple resection)for various pathologies during a five-year period(2017-2021)in a tertiary care setting at university Medical Centre ljubljana,Slovenia and Cattinara Hospital,Trieste,Italy.Short-term postoperative outcomes,namely,postoperative complications,postoperative pancreatic fistula,reoperation,and mortality,were evaluated in association with albumin-bilirubin score and other risk factors.Multiple logistic regression models were built to identify risk factors associated with these short-term postoperative outcomes.RESULTS Data from 347 patients were collected.Postoperative complications,major postoperative complications,postoperative pancreatic fistula,reoperation,and mortality were observed in 52.7%,22.2%,23.9%,21.3%,and 5.2%of patients,respectively.There was no statistically significant association between the albumin-bilirubin score and any of these short-term postoperative complications based on univariate analysis.When controlling for other predictor variables in a logistic regression model,soft pancreatic texture was statistically significantly associated with postoperative complications[odds ratio(OR):2.09;95%confidence interval(95%CI):1.19-3.67];male gender(OR:2.12;95%CI:1.15-3.93),soft pancreatic texture(OR:3.06;95%CI:1.56-5.97),and blo

关键词： Pancreatoduodenectomy Albumin Bilirubin Postoperative complications Pancreatic fistula Perioperative care

Differences in nano-topography and tribochemistry of ZDDP tribofilms from variations in contact configuration with steel and DLC surfaces

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Friction 2022年第2期10卷 296-315页

作者： Lucija COGA Somayeh AKBARI Janez KOVA Mitjan KALIN NanoSciTec GmbH Munich 80687Germany Department of Surface Engineering and Optoelectronics Jo?ef Stefan InstituteLjubljana 1000Slovenia Laboratory for Tribology and Interface Nanotechnology Faculty of Mechanical EngineeringUniversity of LjubljanaLjubljana 1000Slovenia

In this work,we evaluated the effect of the counter-body material(the same or dissimilar)and contact configuration(moving or stationary body),at similar contact tribological conditions,on the tribochemical and nanotopography characteristics of adsorbed surface films.Zinc dialkyldithiophosphate(ZDDP),the best performing anti-wear additive,was used in self-mated steel/steel and DLC/DLC contacts,which were compared with mixed steel/DLC and DLC/steel contacts in 1-h and 6-h sliding tests.The macroscale(tribometer)and nanoscale(atomic force microscopy)friction,thickness,topography,and chemical(attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy)properties of the tribofilms were studied.The results revealed unexpectedly large differences in all the studied tribofilm parameters;this is because all the tribofilms are completely different;this includes the chemical composition,which is known to have a crucial effect on the nano-and macro-scale tribological properties.These results clearly demonstrate that the surface material,additives,and common contact operating parameters,that is,pressure,velocity,and temperature,crucially affect the ZDDP tribofilm as well as the position of the moving or stationary surface within the contact,and the material of the moving/stationary bodies.

关键词： dithiophosphate(ZDDP) diamond-like carbon(DLC) steel tribofilm tribochemistry nano-friction thickness topography

Endplate role in the degenerative disc disease:A brief review

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World Journal of Clinical Cases 2023年第1期11卷 17-29页

作者： Tomaz Velnar Lidija Gradisnik Department of Neurosurgery University Medical Centre LjubljanaLjubljana 1000Slovenia Alma Mater Europaea Maribor Maribor 2000Slovenia Institute of Biomedical Sciences University of MariborUniversity of MariborMaribor 2000Slovenia

The degenerative disease of the intervertebral disc is nowadays an important health problem,which has still not been understood and solved adequately.The vertebral endplate is regarded as one of the vital elements in the structure of the intervertebral disc.Its constituent cells,the chondrocytes in the endplate,may also be involved in the process of the intervertebral disc degeneration and their role is central both under physiological and pathological conditions.They main functions include a role in homeostasis of the extracellular environment of the intervertebral disc,metabolic support and nutrition of the discal nucleus and annulus beneath and the preservation of the extracellular matrix.Therefore,it is understandable that the cells in the endplate have been in the centre of research from several viewpoints,such as development,degeneration and growth,reparation and remodelling,as well as treatment strategies.In this article,we briefly review the importance of vertebral endplate,which are often overlooked,in the intervertebral disc degeneration.

关键词： Intervertebral disc Endplate Degenerative disc disease Chondrocytes Extracellular matrix

Characterization of Curing and Bonding of Wood with Adhesive Mixtures of Liquefied Wood and Hexamethylenediamine

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Journal of Renewable Materials 2023年第2期11卷 991-1001页

作者： JureŽigon VitŠeda PetrČermák MilanŠernek Department of Wood Science and Technology Biotechnical FacultyUniversity of LjubljanaLjubljana1000Slovenia Department of Wood Science and Technology Faculty of Forestry and Wood TechnologyMendel University in BrnoBrno61300Czech Republic

Various crosslinking agents can be added to the formulations of natural-based adhesives for wood bonding in order to achieve better durability and higher strength of the formed joints.In the present study,the effect of hexamethylenediamine(HMDA)addition on the performance of liquefied wood(LW)adhesive for wood bonding is investigated.Differential scanning calorimetry showed the improved thermal stability and crosslinking of the LW adhesive with HMDA.The intensified presence of amide linkages(C–N bonds)was found in LW+HMDA with attenuated total reflection Fourier transform infrared spectroscopy.Analysis of the bonded joints using an automated bonding evaluation system showed that a higher press temperature resulted in stronger bonds for both types of adhesives.Moreover,the addition of HMDA to LW adhesive improved the bond strength of the joints and accelerated the crosslinking of the adhesive.However,with a tensile shear strength of(6.76±2.16)N×mm^(−2)(for LW)and(6.89±2.10)N×mm^(−2)(for LW+HMDA),both adhesives were found to be unsuitable for interior non-structural use.In addition,the acidity of LW resulted in relatively high wood failure(70%)in the adhesive joints tested.Improved crosslinking of LW with HMDA was reflected in improved resistance of LW+HMDA adhesive joints to water degradation.In conclusion,HMDA is a promising additive for improving the adhesive performance of LW adhesives.

关键词： Adhesive bonding hexamethylenediamine liquefied wood