Titanium oxide films were prepared by annealing DC magnetron sputtered titanium films in an oxygen ambient. X-ray diffraction （XRD）, Auger electron spectroscopy （AES） sputter profiling, MCs^＋-mode secondary ion m...Titanium oxide films were prepared by annealing DC magnetron sputtered titanium films in an oxygen ambient. X-ray diffraction （XRD）, Auger electron spectroscopy （AES） sputter profiling, MCs^＋-mode secondary ion mass spectrometry （MCs^＋-SIMS） and atomic force microscopy （AFM） were employed, respectively, for the structural, com- positional and morphological characterization of the obtained films. For temperatures below 875 K, titanium films could not be fully oxidized within one hour. Above that temperature, the completely oxidized films were found to be rutile in structure. Detailed studies on the oxidation process at 925K were carried out for the understanding of the underlying mechanism of titanium dioxide （TiO2） formation by thermal oxidation. It was demonstrated that the formation of crystalline TiO2 could be divided into a short oxidation stage, followed by crystal forming stage. Relevance of this recognition was further discussed.展开更多
Background: Pituitary adenomas represent a quite frequent neurosurgical disease. Secreting pituitary adenomas are represented by PRL, GH, ACTH and TSH tumours;the rate of postoperative hormonal recurrence is not ineli...Background: Pituitary adenomas represent a quite frequent neurosurgical disease. Secreting pituitary adenomas are represented by PRL, GH, ACTH and TSH tumours;the rate of postoperative hormonal recurrence is not ineligible. Methods: We present 106 patients affected by secreting pituitary microadenomas operated through transsphenoidal approach from 1998 through to 2008;in 54 (group 1) patients, intraoperative absolute alcohol was applied, while in the other 52 (group 2) it was not employed. The indications and the intraoperative technique of absolute alcohol application are presented. Hormonal recurrence was treated by hypofractionated stereotactic radiotherapy and/or medical therapy. Results: Postoperative hormonal and clinical remission was achieved in 50 and 47 patients respectively of group one and group two. At the first follow-up control, after 3 months from surgery, no patient of both groups presented hormonal/clinical recurrence. Six months after surgery, no patient of group one presented hormonal recurrence, while two patients of group 2 presented hormonal recurrence. After 2 years from surgery, two patients of group 1 and 4 patients of group 2 presented hormonal recurrence. Three years after operation, hormonal hypersecretion recurred in three patients of group one and in six patients of group 2. At 5 years follow-up, six patients of group one and 8 of group two presented hormonal recurrence. Conclusions: Intraoperative application of absolute alcohol, in selected cases, resulted useful to achieve better results in secreting pituitary microadenomas concerning both postoperative hormonal recurrence and hormonal persistence.展开更多
Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabrica...Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabricated by the hand lay-up process (30:70 fibre and matrix ratio by weight) and the properties evaluated using the INSTRON material testing system. The mechanical properties were tested and showed that glass laminate has the maximum tensile strength of 63 MPa, bending strength of 0.5 MPa, compressive strength of 37.75 MPa and the impact strength of 17.82 J/m2. The ukam plant fibre laminate has the maximum tensile strength of 16.25 MPa and the impact strength of 9.8J/m among the natural fibres;the sisal laminate has the maximum compressive strength of 42 MPa and maximum bending strength of 0.0036 MPa among the natural fibres. Results indicated that natural fibres are of interest for low-cost engineering applications and can compete with artificial glass fibres (E-glass fibre) when a high stiffness per unit weight is desirable. Results also indicated that future research towards significant improvements in tensile and impact strength of these types of composites should focus on the optimisation of fibre strength rather than interfacial bond strength.展开更多
Although the deposition mechanisms of the cold spray process are well studied, few reports regarding the use of surface-modified particles exist. Herein, titanium particles 3-39 μm in size and with an angular shape w...Although the deposition mechanisms of the cold spray process are well studied, few reports regarding the use of surface-modified particles exist. Herein, titanium particles 3-39 μm in size and with an angular shape were modified in a plasma-enhanced chemical vapor deposition process in Ar, Ar-C2H2, and N2 plasmas. After Ar-C2H2 and N2 treatments, the respective presence of TiC and TiN on the particle surface was confirmed via transmission electron microscopy and energy-dispersive X-ray, X-ray photoelectron, and Raman spectroscopies. The powders were deposited on titanium substrates by cold spray experiments, where unmodified particles up to 10(xm in size exhibited a successful surface bon ding. This finding was described by an existing analytical model, whose parameters were achieved by computational fluid dynamics simulations taking the particle shape factor into account:. A good deposition of plasma-modified particles up to 30 μm in size was experimentally observed, exhibiting an upper size limit larger than that predicted by the model. Higher surface roughness values were found for plasmamodified particles, as determined by 3D scanning electron microscopy. The water contact angle indicated that argon treatment influenced the wettability. Tribological tests showed a decrease of the initial friction coefficient from 0.53 to 0.47 by microstructuring.展开更多
Biodiesel is an alternative fuel to replace fossil- based diesel fuel. It has fuel properties similar to diesel which are generally determined experimentally. The experimental determination of various properties of bi...Biodiesel is an alternative fuel to replace fossil- based diesel fuel. It has fuel properties similar to diesel which are generally determined experimentally. The experimental determination of various properties of biodiesel is costly, time consuming and a tedious process. To solve these problems, artificial neural network （ANN） has been considered as a vital tool for estimating the fuel properties of biodiesel, especially from its fatty acid （FA） composition. In this study, four ANNs have been designed and trained to predict the cetane number （CN）, flash point （FP）, kinematic viscosity （KV） and density of biodiesel using ANN with logsig and purelin transfer functions in the hidden layer of all the networks. The five most prevalent FAs from 55 feedstocks found in the literature utilized as the input parameters for the model are palmitic, stearic, oleic, linoleic and linolenie acids except for density network with a sixth parameter （temperature）. Other FAs that are present in the biodiesels have been considered based on the number of carbon atom chains and the level of saturation. From this study, the prediction accuracy and the average absolute deviation of the networks are CN （96.69%; 1.637%）, KV （95.80%; 1.638%）, FP （99.07%; 0.997%） and density （99.40%; 0.101%）. These values are reasonably better compared to previous studies on empirical correlations and ANN predictions of these fuel properties found in literature. Hence, the present study demonstrates the ability of ANN model to predict fuel properties of biodiesel with high accuracy.展开更多
This paper presents the results of the application of a cold spray technique for structuring metallic surfaces with microparticles. The resulting changes in surface properties were characterized to observe their influ...This paper presents the results of the application of a cold spray technique for structuring metallic surfaces with microparticles. The resulting changes in surface properties were characterized to observe their influences on the tribological behavior of the structured surface. The spray technique was applied to a technical component, a 16MnCr5 steel chain pin, designed to be mounted in a linear reciprocating tribometer. TiO2 microparticles were used to structure the surface with a homogeneous distribution of singly dispersed particles, rather than a homogeneous closed coating on the surface. Tribometer tests were performed to directly compare structured and unstructured chain pins, and a significantly reduced sliding friction coefficient was observed for the structured pin. The pins were characterized in detail by surface analysis prior to and after application of the tribological load to set the surface parameters and surface chemistry, even on the microscale. It was confirmed that the particle structuring induced changes in the surface properties, and the durability of the changes after tribological loading was evaluated.展开更多
Introduction:Machine learning (ML)‐based facial nerve injury (FNI) forecasting grounded on multicentric data has not been released up to now.Three distinct ML models,random forest (RF),K‐nearest neighbor,and artific...Introduction:Machine learning (ML)‐based facial nerve injury (FNI) forecasting grounded on multicentric data has not been released up to now.Three distinct ML models,random forest (RF),K‐nearest neighbor,and artificial neural network (ANN),for the prediction of FNI were evaluated in this mode.Methods:A retrospective,longitudinal,multicentric study was performed,including patients who went through parotid gland surgery for benign tumors at three different university hospitals.Results:Seven hundred and thirty‐six patients were included.The most compelling aspects related to risk escalation of FNI were as follows:(1) location,in the mid‐portion of the gland,near to or above the main trunk of the facial nerve and at the top part,over the frontal or the orbital branch of the facial nerve;(2) tumor volume in the anteroposterior axis;(3) the necessity to simultaneously dissect more than one level;and (4) the requirement of an extended resection compared to a lesser extended resection.By contrast,in accordance with the ML analysis,the size of the tumor (>3 cm),as well as gender and age did not result in a determining favor in relation to the risk of FNI.Discussion:The findings of this research conclude that ML models such as RF and ANN may serve evidence‐based predictions from multicentric data regarding the risk of FNI.Conclusion:Along with the advent of ML technology,an improvement of the information regarding the potential risks of FNI associated with patients before each procedure may be achieved with the implementation of clinical,radiological,histological,and/or cytological data.展开更多
Recently, mixture of different oils at various proportions have been used as feedstock for biodiesel production. The primary aim is to improve fuel properties which are strongly influenced by the fatty acid compositio...Recently, mixture of different oils at various proportions have been used as feedstock for biodiesel production. The primary aim is to improve fuel properties which are strongly influenced by the fatty acid composition of the individual oil that makes up the feedstock mix. The tropics are renowned for abundant oil-bearing crops of which palm kernel oil （PKO） from palm seed and groundnut oil （GNO） are prominent. This present paper investigated biodiesel production from hybrid oil （HO） of PKO （medium carbon chain and highly saturated oil） and GNO （long carbon chain and highly unsaturated oil） at 50/ 50 （v/v） blending. The principal fatty acids （FAs） in the HO are oleic （35.62%） and lauric acids （24.23%） with 47.80% of saturated FA and 52.26% of unsaturated FA contents. The chemical conversion of the oil to methyl ester （ME） gave 86.56% yield. Fuel properties of hybrid oil methyl ester （the HOME） were determined in accordance with standard test methods and were found to comply with both ASTM D6751 and EN 14214 standards. The oxidative stability, cetane number and kinematic viscosity （KV） of HOME were observed to be improved when compared with those of GNO methyl ester from single parent oil, which could be accredited to the improved FA composition of the HO. The KV （3.69 minE/s） of HOME obtained in this paper was remarkably low compared with those reported in literature for most biodiesels. This value suggests better flow, atomization, spray and combustion of this fuel. Conclusively, the binary blend of oils can be a viable option to improve the fuel properties ofbiodiesel feedstock coupled with reduced cost.展开更多
文摘Titanium oxide films were prepared by annealing DC magnetron sputtered titanium films in an oxygen ambient. X-ray diffraction （XRD）, Auger electron spectroscopy （AES） sputter profiling, MCs^＋-mode secondary ion mass spectrometry （MCs^＋-SIMS） and atomic force microscopy （AFM） were employed, respectively, for the structural, com- positional and morphological characterization of the obtained films. For temperatures below 875 K, titanium films could not be fully oxidized within one hour. Above that temperature, the completely oxidized films were found to be rutile in structure. Detailed studies on the oxidation process at 925K were carried out for the understanding of the underlying mechanism of titanium dioxide （TiO2） formation by thermal oxidation. It was demonstrated that the formation of crystalline TiO2 could be divided into a short oxidation stage, followed by crystal forming stage. Relevance of this recognition was further discussed.
文摘Background: Pituitary adenomas represent a quite frequent neurosurgical disease. Secreting pituitary adenomas are represented by PRL, GH, ACTH and TSH tumours;the rate of postoperative hormonal recurrence is not ineligible. Methods: We present 106 patients affected by secreting pituitary microadenomas operated through transsphenoidal approach from 1998 through to 2008;in 54 (group 1) patients, intraoperative absolute alcohol was applied, while in the other 52 (group 2) it was not employed. The indications and the intraoperative technique of absolute alcohol application are presented. Hormonal recurrence was treated by hypofractionated stereotactic radiotherapy and/or medical therapy. Results: Postoperative hormonal and clinical remission was achieved in 50 and 47 patients respectively of group one and group two. At the first follow-up control, after 3 months from surgery, no patient of both groups presented hormonal/clinical recurrence. Six months after surgery, no patient of group one presented hormonal recurrence, while two patients of group 2 presented hormonal recurrence. After 2 years from surgery, two patients of group 1 and 4 patients of group 2 presented hormonal recurrence. Three years after operation, hormonal hypersecretion recurred in three patients of group one and in six patients of group 2. At 5 years follow-up, six patients of group one and 8 of group two presented hormonal recurrence. Conclusions: Intraoperative application of absolute alcohol, in selected cases, resulted useful to achieve better results in secreting pituitary microadenomas concerning both postoperative hormonal recurrence and hormonal persistence.
文摘Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabricated by the hand lay-up process (30:70 fibre and matrix ratio by weight) and the properties evaluated using the INSTRON material testing system. The mechanical properties were tested and showed that glass laminate has the maximum tensile strength of 63 MPa, bending strength of 0.5 MPa, compressive strength of 37.75 MPa and the impact strength of 17.82 J/m2. The ukam plant fibre laminate has the maximum tensile strength of 16.25 MPa and the impact strength of 9.8J/m among the natural fibres;the sisal laminate has the maximum compressive strength of 42 MPa and maximum bending strength of 0.0036 MPa among the natural fibres. Results indicated that natural fibres are of interest for low-cost engineering applications and can compete with artificial glass fibres (E-glass fibre) when a high stiffness per unit weight is desirable. Results also indicated that future research towards significant improvements in tensile and impact strength of these types of composites should focus on the optimisation of fibre strength rather than interfacial bond strength.
文摘Although the deposition mechanisms of the cold spray process are well studied, few reports regarding the use of surface-modified particles exist. Herein, titanium particles 3-39 μm in size and with an angular shape were modified in a plasma-enhanced chemical vapor deposition process in Ar, Ar-C2H2, and N2 plasmas. After Ar-C2H2 and N2 treatments, the respective presence of TiC and TiN on the particle surface was confirmed via transmission electron microscopy and energy-dispersive X-ray, X-ray photoelectron, and Raman spectroscopies. The powders were deposited on titanium substrates by cold spray experiments, where unmodified particles up to 10(xm in size exhibited a successful surface bon ding. This finding was described by an existing analytical model, whose parameters were achieved by computational fluid dynamics simulations taking the particle shape factor into account:. A good deposition of plasma-modified particles up to 30 μm in size was experimentally observed, exhibiting an upper size limit larger than that predicted by the model. Higher surface roughness values were found for plasmamodified particles, as determined by 3D scanning electron microscopy. The water contact angle indicated that argon treatment influenced the wettability. Tribological tests showed a decrease of the initial friction coefficient from 0.53 to 0.47 by microstructuring.
文摘Biodiesel is an alternative fuel to replace fossil- based diesel fuel. It has fuel properties similar to diesel which are generally determined experimentally. The experimental determination of various properties of biodiesel is costly, time consuming and a tedious process. To solve these problems, artificial neural network （ANN） has been considered as a vital tool for estimating the fuel properties of biodiesel, especially from its fatty acid （FA） composition. In this study, four ANNs have been designed and trained to predict the cetane number （CN）, flash point （FP）, kinematic viscosity （KV） and density of biodiesel using ANN with logsig and purelin transfer functions in the hidden layer of all the networks. The five most prevalent FAs from 55 feedstocks found in the literature utilized as the input parameters for the model are palmitic, stearic, oleic, linoleic and linolenie acids except for density network with a sixth parameter （temperature）. Other FAs that are present in the biodiesels have been considered based on the number of carbon atom chains and the level of saturation. From this study, the prediction accuracy and the average absolute deviation of the networks are CN （96.69%; 1.637%）, KV （95.80%; 1.638%）, FP （99.07%; 0.997%） and density （99.40%; 0.101%）. These values are reasonably better compared to previous studies on empirical correlations and ANN predictions of these fuel properties found in literature. Hence, the present study demonstrates the ability of ANN model to predict fuel properties of biodiesel with high accuracy.
基金financially supported by the German Research Foundation(DFG) Collaborative Research Center 926,Kaiserslautern,Germany "Microscale Morphology of Component Surfaces"
文摘This paper presents the results of the application of a cold spray technique for structuring metallic surfaces with microparticles. The resulting changes in surface properties were characterized to observe their influences on the tribological behavior of the structured surface. The spray technique was applied to a technical component, a 16MnCr5 steel chain pin, designed to be mounted in a linear reciprocating tribometer. TiO2 microparticles were used to structure the surface with a homogeneous distribution of singly dispersed particles, rather than a homogeneous closed coating on the surface. Tribometer tests were performed to directly compare structured and unstructured chain pins, and a significantly reduced sliding friction coefficient was observed for the structured pin. The pins were characterized in detail by surface analysis prior to and after application of the tribological load to set the surface parameters and surface chemistry, even on the microscale. It was confirmed that the particle structuring induced changes in the surface properties, and the durability of the changes after tribological loading was evaluated.
文摘Introduction:Machine learning (ML)‐based facial nerve injury (FNI) forecasting grounded on multicentric data has not been released up to now.Three distinct ML models,random forest (RF),K‐nearest neighbor,and artificial neural network (ANN),for the prediction of FNI were evaluated in this mode.Methods:A retrospective,longitudinal,multicentric study was performed,including patients who went through parotid gland surgery for benign tumors at three different university hospitals.Results:Seven hundred and thirty‐six patients were included.The most compelling aspects related to risk escalation of FNI were as follows:(1) location,in the mid‐portion of the gland,near to or above the main trunk of the facial nerve and at the top part,over the frontal or the orbital branch of the facial nerve;(2) tumor volume in the anteroposterior axis;(3) the necessity to simultaneously dissect more than one level;and (4) the requirement of an extended resection compared to a lesser extended resection.By contrast,in accordance with the ML analysis,the size of the tumor (>3 cm),as well as gender and age did not result in a determining favor in relation to the risk of FNI.Discussion:The findings of this research conclude that ML models such as RF and ANN may serve evidence‐based predictions from multicentric data regarding the risk of FNI.Conclusion:Along with the advent of ML technology,an improvement of the information regarding the potential risks of FNI associated with patients before each procedure may be achieved with the implementation of clinical,radiological,histological,and/or cytological data.
文摘Recently, mixture of different oils at various proportions have been used as feedstock for biodiesel production. The primary aim is to improve fuel properties which are strongly influenced by the fatty acid composition of the individual oil that makes up the feedstock mix. The tropics are renowned for abundant oil-bearing crops of which palm kernel oil （PKO） from palm seed and groundnut oil （GNO） are prominent. This present paper investigated biodiesel production from hybrid oil （HO） of PKO （medium carbon chain and highly saturated oil） and GNO （long carbon chain and highly unsaturated oil） at 50/ 50 （v/v） blending. The principal fatty acids （FAs） in the HO are oleic （35.62%） and lauric acids （24.23%） with 47.80% of saturated FA and 52.26% of unsaturated FA contents. The chemical conversion of the oil to methyl ester （ME） gave 86.56% yield. Fuel properties of hybrid oil methyl ester （the HOME） were determined in accordance with standard test methods and were found to comply with both ASTM D6751 and EN 14214 standards. The oxidative stability, cetane number and kinematic viscosity （KV） of HOME were observed to be improved when compared with those of GNO methyl ester from single parent oil, which could be accredited to the improved FA composition of the HO. The KV （3.69 minE/s） of HOME obtained in this paper was remarkably low compared with those reported in literature for most biodiesels. This value suggests better flow, atomization, spray and combustion of this fuel. Conclusively, the binary blend of oils can be a viable option to improve the fuel properties ofbiodiesel feedstock coupled with reduced cost.
