scholarly journals Room and High Temperature Tribological Performance of Multilayered TiSiN/TiN and TiSiN/TiN(Ag) Coatings Deposited by Sputtering

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1191
Author(s):  
Filipe Fernandes ◽  
Abbas AL-Rjoub ◽  
Diogo Cavaleiro ◽  
Tomas Polcar ◽  
Albano Cavaleiro
Keyword(s):  
Wear Debris ◽  
Room Temperature ◽  
Solid Lubricant ◽  
Wear Track ◽  
Tribological Performance ◽  
Tin Coating ◽  
Reduced Modulus ◽  
Adhesion Wear ◽  
Si Content ◽  
Better Than

In this study, we compare the tribological performance of a multilayer TiSiN/Ti(Ag)N coating with a TiSiN/TiN coating with a similar Si content in order to demonstrate the effect of the solid lubricant phase, silver. For Al2O3 balls, the hardness and reduced modulus determine the tribological performance of the coatings for tests conducted at room temperature (RT) against Al2O3 balls. At 550 °C, the TiSiN/TiN coating failed, whereas the Ag-containing coating performed better due to the presence of Ag in the contact, which decreased the shear stress and, consequently, the friction. For tests against TiAl6V4 balls, the Ag-containing coating was always better than the TiSiN/TiN one. At 550 °C, Ag in the wear track prevented the adhesion of the oxidized Ti-alloy wear debris in the contact, favoring the adhesion of wear debris from the coating to both the coating and counterpart surfaces. No wear could be measured for the 700 °C tests for both coatings due to different reasons: (i) the presence of oxidized adhered material from the ball to the reference TiSiN/TiN coating surface protected from wear and (ii) the presence of Ag-agglomerated particles decreased the friction and minimized the adhesion wear of the counterpart for the TiSiN/TiN(Ag) coating.

scholarly journals Novel technology for storage and distribution of live vaccines and other biological medicines at ambient temperature

2020 ◽  
Vol 6 (10) ◽  
pp. eaau4819 ◽  
Author(s):  
Irnela Bajrovic ◽  
Stephen C. Schafer ◽  
Dwight K. Romanovicz ◽  
Maria A. Croyle
Keyword(s):  
Room Temperature ◽  
Recombinant Adenovirus ◽  
Amorphous Solid ◽  
Live Virus ◽  
Live Vaccines ◽  
Novel Technology ◽  
Production Distribution ◽  
Global Access ◽  
Reducing Costs ◽  
Better Than

A novel, thin-film platform that preserves live viruses, bacteria, antibodies, and enzymes without refrigeration for extended periods of time is described. Studies with recombinant adenovirus in an optimized formulation that supports recovery of live virus through 16 freeze-thaw cycles revealed that production of an amorphous solid with a glass transition above room temperature and nitrogen-hydrogen bonding between virus and film components are critical determinants of stability. Administration of live influenza virus in the optimized film by the sublingual and buccal routes induced antibody-mediated immune responses as good as or better than those achieved by intramuscular injection. This work introduces the possibility of improving global access to a variety of medicines by offering a technology capable of reducing costs of production, distribution, and supply chain maintenance.

Enhanced Tribological Performance of CVD Diamond Films Enabled by Using Graphene Layers as Solid Lubricant

2016 ◽  
Vol 1136 ◽  
pp. 573-578 ◽  
Author(s):  
Su Lin Chen ◽  
Bin Shen ◽  
Fang Hong Sun
Keyword(s):  
Tungsten Carbide ◽  
Solid Lubricant ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Tribological Performance ◽  
Chemical Vapor Deposition Method ◽  
Dry Sliding ◽  
Graphene Layers ◽  
Sliding Interface ◽  
Graphene Flakes

The present study reports the influence of graphene layers on the tribological performance of CVD diamond films when they are used as the solid lubricants. Friction tests are conducted on a ball-on-plate friction tester, where the stainless steel is used as the counterpart material. The CVD diamond film sample is a typical microcrystalline diamond (MCD) coating which is deposited on a flat tungsten carbide substrate using the hot filament chemical vapor deposition method (HFCVD). Besides the MCD sample, a polished MCD film (pMCD) and a polished tungsten carbide (pWC) are also adopted in frictional tests, aiming at illustrating the influence of the surface morphology, as well as the physical property, of the sample on the lubricative effect of graphene layers. The experimental results show that graphene layers can effectively reduce the coefficient of friction (COF), regardless of the samples. The MCD sample presents the lowest stable COF, which is 0.13, in dry sliding period when the graphene flakes are sparyed on the sliding interface; while the pMCD and pWC samples exhibit slightly higher COFs, which are 0.16 and 0.18, respectively. Comparatively, the COFs of these three samples obtained in dry sliding process without graphene are 0.20, 0.25 and 0.64. In additon, the MCD sample exhibits a much longer stable dry slidng process which is more than 5000 cycles. Comparatively, the other two tribo-pairs only exhibit a stable low-COF dry sliding period for around 2000 cycles. The reduction of COF could be attributed to the graphene flakes adhered on the sliding interface. It forms a layer of solid lubricative film with extremely low shear strength and significantly decreases the interactions between two contacted surfaces. The rugged surface of the MCD film provides sufficient clogging locations for graphene flakes, which allows the generated lubricative film enduring a long sliding duration. It can be arrived from this study that the tribological properties of the MCD film could be enhanced by simply adoping graphene layers as a solid lubricant. Furthermore, an improved performance of a variety of MCD coated cutting tools or mechanical components could be expected when they are utilized with graphene layers.

Room Temperature Band-Edge Luminescence from Silicon Grains Prepared by the Recrystallization of Mesoporous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
Karen L. Moore ◽  
Leonid Tsybeskov ◽  
Philippe M. Fauchet ◽  
Dennis G. Hall
Keyword(s):  
Room Temperature ◽  
Silicon Oxide ◽  
Crystalline Silicon ◽  
Band Edge ◽  
Applied Bias ◽  
Mesoporous Silicon ◽  
Room Temperature Photoluminescence ◽  
Band Edge Luminescence ◽  
A Current ◽  
Better Than

AbstractRoom-temperature photoluminescence (PL) peaking at 1.1 eV has been found in electrochemically etched mesoporous silicon annealed at 950°C. Low-temperature PL spectra clearly show a fine structure related to phonon-assisted transitions in pure crystalline silicon (c-Si) and the absence of defect-related (e.g.P-line) and impurity-related (e.g.oxygen, boron) transitions. The maximum PL external quantum efficiency (EQE) is found to be better than 0.1% with a weak temperature dependence in the region from 12K to 400K. The PL intensity is a linear function of excitation intensity up to 100 W/cm2. The PL can be suppressed by an external electric field ≥ 105 V/cm. Room temperature electroluminescence (EL) related to the c-Si band-edge is also demonstrated under an applied bias ≤ 1.2 V and with a current density ≈ 20 mA/cm2. A model is proposed in which the radiative recombination originates from recrystallized Si grains within a non-stoichiometric Si-rich silicon oxide (SRSO) matrix.

scholarly journals Grafting Improves Fruit Yield of Cucumber Plants Grown under Combined Heat and Soil Salinity Stresses

Horticulturae ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 61
Author(s):  
Yousry Bayoumi ◽  
Emad Abd-Alkarim ◽  
Hassan El-Ramady ◽  
Farouk El-Aidy ◽  
El-Samahy Hamed ◽  
...  
Keyword(s):  
Arid Regions ◽  
Saline Soil ◽  
Growth Yield ◽  
High Temperature Stress ◽  
Cucumis Sativus L ◽  
Chlorophyll Contents ◽  
Flower Abortion ◽  
Yield Quality ◽  
Si Content ◽  
Better Than

Improving the productivity of cucumber (Cucumis sativus L.) plants subjected to combined salinity and heat stresses is a significant challenge, particularly in arid and semi-arid regions. Gianco F1 cucumbers were grafted onto five cucurbit rootstocks and, together with an ungrafted control, were grown in Egypt in a net house with saline soil during the summer season over two years. The vegetative growth, yield, quality, biochemical, and mineral composition traits were measured. Although many differences were observed among treatments, in general, the grafted plants had a performance better than or similar to that of the ungrafted plants, based on the different parameters measured. In particular, the cucumber plants grafted onto the Cucurbita maxima × C. moschata interspecific hybrid rootstocks VSS-61 F1 and Ferro had the highest early and total marketable yields. These two rootstocks consistently conferred higher vigor to the scion, which had lower flower abortion rates and higher chlorophyll contents. The fruit quality and N, P, and K composition in the leaves suffered few relevant changes as compared with the control. However, the leaves of the VSS-61 F1 had higher catalase activity, as well as proline and Se contents, while those of Ferro had higher Si content. This study reveals that the grafting of cucumber plants onto suitable rootstocks may mitigate the adverse effects caused by the combination of saline soil and heat stresses. This represents a significant improvement for cucumber cultivation in saline soil under high-temperature stress conditions in arid regions.

Newly Developed Heat Resistant Magnesium Alloy by Thixomolding®

2005 ◽  
Vol 488-489 ◽  
pp. 287-290 ◽  
Author(s):  
Tadayoshi Tsukeda ◽  
Ken Saito ◽  
Mayumi Suzuki ◽  
Junichi Koike ◽  
Kouichi Maruyama
Keyword(s):  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Die Casting ◽  
The Other ◽  
Heat Resistant ◽  
Higher Temperature ◽  
Better Than

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.

Modeling of Nonlinear Viscoelastic Creep of Polycarbonate

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Wenbo Luo ◽  
Said Jazouli ◽  
Toan Vu-Khanh
Keyword(s):  
Creep Behavior ◽  
Room Temperature ◽  
Multiple Integral ◽  
Model Fit ◽  
Viscoelastic Creep ◽  
Commercial Grade ◽  
Nonlinear Viscoelastic ◽  
Schapery Model ◽  
Special Case ◽  
Better Than

AbstractThe creep behavior of a commercial grade polycarbonate was investigated in this study. 10 different constant stresses ranging from 8 MPa to 50 MPa were applied to the specimen, and the resultant creep strains were measured at room temperature. It was found that the creep could be modeled linearly below 15 MPa, and nonlinearly above 15 MPa. Different nonlinear viscoelastic models have been briefly reviewed and used to fit the test data. It is shown that the Findley model is a special case of the Schapery model, and both the Findley model and the simplified multiple integral representation are suitable for properly describing the creep behavior of the polycarbonate investigated in this paper; however, the Findley model fit the data better than the simplified multiple integral with three terms.

scholarly journals Evaluasi Penyimpanan Spermatozoa Ayam Pada Suhu 5⁰C, 26⁰C Dengan Pengencer Infuse NaCl, Glukosa 5% dan 10%

2021 ◽  
pp. 10-19
Author(s):  
Asnawi Asnawi ◽  
Maskur Maskur ◽  
Adji Santoso Dradjat
Keyword(s):  
Cold Storage ◽  
Room Temperature ◽  
Storage Temperature ◽  
Room Temperature Storage ◽  
C Storage ◽  
Better Than ◽  
Temperature Storage

The purpose of this study were to compare the quality of spermatozoa stored at 26⁰C, 5⁰C using diluents of NaCl, 10% glucose and 5% glucose. The spermatozoa of a rooster was collected and divided into 6 parts, each 2 tubes diluted in a ratio of 1:1 using NaCl, Glucose5% and Glucose 10%, then each 3 tubes with different diluents were stored at 26⁰C and 5⁰C. Observations of motility, viability and abnormalities of spermatozoa were carried out half an hour, 1 hour after dilution, followed every 2 hours until the ninth hours. The results showed that spermatozoa stored for 9 hours at a temperature of 26⁰C with a physiological diluent of NaCl, 10% Glucose and 5% Glucose each were different (P, < 0.05) with motility 50 ± 0.0%, 42 ± 10.95. % and 34±8.94%, respectively. At storage temperature of 5⁰C for 9 hours, physiological NaCl, 10% glucose and 5% glucose were significantly different (P<0.05) with motility 58.00±10.95%, 46.00±8.94% and 38.00±, respectively. 10.95% in a row. The viability of spermatozoa at 26⁰C storage with 5% glucose diluent was better than 10% glucose and physiological NaCl (P<0.05), 58.93±1.27%, 42.93±1.48% and 33.43±1.27% , while the physiological NaCl diluent and 10% glucose were not significantly different (P>0.05). At 5⁰C storage the viability of spermatozoa in the three diluents was not significantly different, with values of Glucose 10%, Glucose 5% and physiological NaCl 52.57±5.15%, 52.21±5.02% and 48.14±8.09%, respectively. Spermatozoa abnormalities at storage temperature 26⁰C and 5⁰C for 9 hours using physiological NaCl diluent, 5% glucose and 10% glucose, were not significantly different and varied between 5 to 10%. Finally, it can be concluded that at room temperature storage less than 4 hours the quality of spermatozoa was better with 5% glucose diluent, while for cold storage beyond 4 hours the quality of spermatozoa with NaCl diluent was higher

scholarly journals Production of Nigerian Yoghurt Using Lactic Acid Bacteria as Starter Cultures

2020 ◽  
pp. 32-42
Author(s):  
S. Aforijiku ◽  
S. M. Wakil ◽  
A. A. Onilude
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Proximate Composition ◽  
Room Temperature ◽  
Starter Cultures ◽  
Cow Milk ◽  
Spontaneous Fermentation ◽  
Overall Acceptability ◽  
Fermentation Control ◽  
Better Than

Aim: This work was carried out to investigate the influence of Lactic Acid Bacteria (LAB) on organoleptic quality and proximate composition of yoghurt, and viability of starter cultures in yoghurt. Methods: The LAB starter cultures were selected based on their ability to produce diacetyl and lactic acid. Results: Lactobacillus caseiN1 produced the highest quantity (2.72 g/L) of diacetyl at 48 hrs of incubation while Pediococcus acidilacticiG1 had the lowest amount (0.50 g/L). The pH of produced yoghurt ranged between 4.40 and 5.58 while the corresponding lactic acid contents ranged between 0.70 and 0.96 g/L. Yoghurt produced with cow milk inoculated with L. PlantarumN24 and L. BrevisN10 had the lowest pH (4.40) at significant level of P≤0.05. Yoghurt with mixed culture of L. PlantarumN24 and L. PlantarumN17 had the highest protein content (5.13%) while spontaneous fermentation (control) produced the least (0.48%). Yoghurt produced from cow milk inoculated with L. PlantarumN24 and L. PlantarumN17 was rated best with overall acceptability (9.0) during first day of storage while the commercial yoghurt (5.8) and spontaneous fermentation (6.8) had least overall acceptability at P≤0.05. Conclusion: Yoghurt samples stored in refrigerator had more viable LAB counts for a period of 21 days while the samples stored at room temperature had a day count except for yoghurt produced with cow milk inoculated with L. plantarumN24 which retained its viability at the second day. The yoghurt produced with selected LAB starters are better than commercial yoghurt in terms of sensory properties, proximate composition, pH and viability.

Tribological and Corrosion Behavior of HVOF Sprayed Cr3C2-NiCr with Nickel Cladded Graphite and Hexagonal Boron Nitride

2021 ◽  
Author(s):  
M. Oechsner ◽  
T. Engler ◽  
H. Scheerer ◽  
Y. Joung ◽  
K. Bobzin ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Friction And Wear ◽  
Room Temperature ◽  
Solid Lubricant ◽  
Hexagonal Boron Nitride ◽  
Solid Lubricants ◽  
Wear Behaviour ◽  
Wear Volume ◽  
Coating Microstructure ◽  
Sprayed Coatings

Abstract High-velocity oxyfuel (HVOF) sprayed coatings of Cr3C2-NiCr containing solid lubricants such as nickel cladded graphite and hexagonal boron nitride were successfully developed and characterised with the aim of optimizing their friction and wear behaviour. HVOF technology was used for the integration of solid lubricants to achieve strong cohesion between particles while minimizing thermal decomposition. Coating microstructure and composition were measured and correlated to the results of tribological and corrosion tests. The integration of the solid lubricant greatly reduced friction and wear volume at room temperature, but the lubricating effect was highly dependent on atmosphere and temperature. Cr3C2-NiCr with hBN, however, tends to exhibit more stable wear resistance over a wider temperature range and can be used at temperatures beyond 450 °C.

Effect of Si, Sr Additions on Microstructure and Mechanical Properties of AZ91 Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 179-182
Author(s):  
S.B. Li ◽  
Zhi Wen Zou ◽  
Shou Mei Xiong
Keyword(s):  
Mechanical Properties ◽  
Silicon Content ◽  
Room Temperature ◽  
Chinese Script ◽  
Az91 Alloy ◽  
Permanent Mold ◽  
Remarkable Effect ◽  
Mg2si Phase ◽  
Β Phase ◽  
Si Content

In present work, Si and Sr elements were added into AZ91 alloy and cast directly into test samples using permanent mold. Mechanical properties of the samples at room temperature were evaluated by tensile test and the microstructure was analyzed. The results show that β-phase (Mg17Al12) of AZ91 alloy decreases with the addition of Si element and Mg2Si phase forms at the same time. Irregular Mg2Si phase precipitates preferentially at the grain boundaries at a low silicon content level. With the increase of the Si content, Mg2Si phase shows a complicated “Chinese- script” shape distributed at the grain boundary which leads to a lower ultimate tensile strength. Subsequently, the addition of Sr element has a remarkable effect on the form and distribution of Mg2Si phase of AZ91-Si alloys.

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