scholarly journals Morphological and Tribological Properties of PMMA/Halloysite Nanocomposites

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 816 ◽  
Author(s):  
Zina Vuluga ◽  
Mihai Corobea ◽  
Cristina Elizetxea ◽  
Mario Ordonez ◽  
Marius Ghiurea ◽  
...  

From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N′-ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.

2018 ◽  
Author(s):  
J. Lindsay ◽  
P. Trimby ◽  
J. Goulden ◽  
S. McCracken ◽  
R. Andrews

Abstract The results presented here show how high-speed simultaneous EBSD and EDS can be used to characterize the essential microstructural parameters in SnPb solder joints with high resolution and precision. Analyses of both intact and failed solder joints have been carried out. Regions of strain localization that are not apparent from the Sn and Pb phase distribution are identified in the intact bond, providing key insights into the mechanism of potential bond failure. In addition, EBSD provides a wealth of quantitative detail such as the relationship between parent Sn grain orientations and Pb coarsening, the morphology and distribution of IMCs on a sub-micron scale and accurate grain size information for all phases within the joint. Such analyses enable a better understanding of the microstructural developments leading up to failure, opening up the possibility of improved accelerated thermal cycling (ATC) testing and better quality control.


2011 ◽  
Vol 14 (2) ◽  
Author(s):  
Thomas G Koch

Current estimates of obesity costs ignore the impact of future weight loss and gain, and may either over or underestimate economic consequences of weight loss. In light of this, I construct static and dynamic measures of medical costs associated with body mass index (BMI), to be balanced against the cost of one-time interventions. This study finds that ignoring the implications of weight loss and gain over time overstates the medical-cost savings of such interventions by an order of magnitude. When the relationship between spending and age is allowed to vary, weight-loss attempts appear to be cost-effective starting and ending with middle age. Some interventions recently proven to decrease weight may also be cost-effective.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 296-297
Author(s):  
Daniela M Meléndez ◽  
Sonia Marti ◽  
Luigi Faucitano ◽  
Derek B Haley ◽  
Timothy D Schwinghamer ◽  
...  

Abstract Blood metabolites are used to assess a variety of animal conditions for veterinary diagnosis and research. Concentration of metabolites in blood can be measured using a commercially-available lab-based assay or in real-time using a handheld device developed to be more time- and cost-effective than the lab-based method. Lactate is a product of anaerobic glycolysis, used in animal research as an indicator of muscle fatigue. Therefore, it has been used as an indicator of cattle response to long distance transportation. The aim of this study was to assess the relationship of L-lactate concentrations measured using a Lactate Scout+ analyzer (Lactate Scout, EFK Diagnostics, Barleben, Germany) and a lactate assay colorimetric kit (Lactate Assay Kit, Cell Biolabs Inc., San Diego, CA). Blood samples were collected by venipuncture from 96 steers (245 ± 35.7 kg BW) prior to (L1) and after 36 h, and prior to and after an additional 4 h of road transportation, and on d 1, 2, 3, 5, 14, and 28 after transport. The Lactate Scout+ analyzer strip was dipped in blood at the time of sampling, while blood samples were collected into sodium fluoride tubes for use in colorimetric analysis. Pearson correlations were calculated to determine the relationship between the experimental methods for the quantification of L-lactate concentrations. The strengths and levels of statistical significance of the correlation varied over the observed time points, r = -0.03, P = 0.75 (L1) to r = 0.75, P = < 0.0001 (d 3). The correlation for the pooled data was weak but statistically significant (r = 0.33, P < 0.001). Based on the experimental results, the Lactate Scout+ analyzer is not a suitable alternative to a lab-based assay for measuring L-lactate in transported cattle, due to variability across sampling time points and weak correlation with the traditional enzymatic method.


Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3234
Author(s):  
Wangwang Yu ◽  
Lili Dong ◽  
Wen Lei ◽  
Yuhan Zhou ◽  
Yongzhe Pu ◽  
...  

To develop a new kind of environment-friendly composite filament for fused deposition modeling (FDM) 3D printing, rice straw powder (RSP)/poly(lactic acid) (PLA) biocomposites were FDM-3D-printed, and the effects of the particle size and pretreatment of RSP on the properties of RSP/PLA biocomposites were investigated. The results indicated that the 120-mesh RSP/PLA biocomposites (named 120#RSP/PLA) showed better performance than RSP/PLA biocomposites prepared with other RSP sizes. Infrared results showed that pretreatment of RSP by different methods was successful, and scanning electron microscopy indicated that composites prepared after pretreatment exhibited good interfacial compatibility due to a preferable binding force between fiber and matrix. When RSP was synergistically pretreated by alkaline and ultrasound, the composite exhibited a high tensile strength, tensile modulus, flexural strength, and flexural modulus of 58.59, 568.68, 90.32, and 3218.12 MPa, respectively, reflecting an increase of 31.19%, 16.48%, 18.75%, and 25.27%, respectively, compared with unmodified 120#RSP/PLA. Pretreatment of RSP also improved the thermal stability and hydrophobic properties, while reducing the water absorption of 120#RSP/PLA. This work is believed to provide highlights of the development of cost-effective biocomposite filaments and improvement of the properties of FDM parts.


2014 ◽  
Vol 878 ◽  
pp. 450-458
Author(s):  
Ling Jun Kong ◽  
Xiong Fei Zhang ◽  
Shuang Hong Tian ◽  
Ting Liu ◽  
Ya Xiong

Densified biomass pellets named as H/S-BPs were prepared from waste wood sawdust (S) in the presence of water hyacinth fiber (H) as solid bridge under room temperature and 6 MPa lower than in the previous study. Mechanical properties including relaxed density (ρr), resiliency (R), abrasion resistance (AR) and impact resistance index (IRI) were evaluated. Results showed that adding H greatly reduced negative effect of resiliency on the mechanical properties of H/S-BPs during storage. For example, H/S-BPs compressed at 6 MPa in an H/S mass ratio of 1 to 3 presented lower resiliency of 10% and higher relaxed density of 1.04 kg dm-3 than pellets without H fiber. This is due to the intertwining action of H fiber, what fabricates solid bridge, replacing the bonding creating by applying high pressure to resist the disruptive force caused by elastic recovery. Thus, compression of waste H and S in a mass ratio of 1 to 3 at room temperature under 6 MPa is a cost-effective process to produce densified sustainable bio-fuel pellet as well as dispose waste S and H, combining the economical and environmental benefits.


2021 ◽  
pp. 22-35
Author(s):  
Stanislav V. Pechinskii ◽  
Eduard T. Oganesyan ◽  
Anna G. Kuregyan

Molecular docking is a convenient and cost-effective tool for targeted screening of biologically active structures. This method makes it possible to reveal the relationship between structure and activity, as well as to search for new active compounds. Due to the fact that the antiviral activity of flavonoids and their derivatives has been shown experimentally and clinically, the study of their antiviral activity against SARS-CoV-2 is a promising study. In an in silico experiment, the possibility of binding 20 flavonoid ligands and the main protease SARS-CoV-2 was studied. The structural features of flavone and flavanone derivatives have been determined, which determine their ability to block the main protease of the SARS-CoV-2 virus. Structures of eight new candidates that bind the main protease SARS-CoV-2, which have the prospect of synthesis and further pharmacological research, have been proposed.


Author(s):  
Filiz Güldaval ◽  
Ceyda Anar ◽  
Mine Gayaf ◽  
Gulru Polat ◽  
Merve Ayık Türk ◽  
...  

Objective: Various studies have reported that the neutrophil-to-lymphocyte ratio in the serum (sNLR) may serve as a cost-effective and useful prognostic factor in patients with various cancer types. We investigated the clinical impact of NLR as a prognostic factor in malign pleural effusion (MPE) and sNLR on prognosis in MPE. Method: We retrospectively reviewed all of the patients who were diagnosed MPE. The relationship between sNLR and neutrophil-to-lymphocyte ratio in the malign pleural effusion (mNLR) value, age, Eastern Cooperative Oncology Group (ECOG), histopathologic type, serum albumin and lactate dehydrogenase (LDH) with survival were investigated. Results: A total of 222 patients with a mean age of 65.7±11.5 were included in the study. Patients with a mNLR value ≥0.42 and a serum NLR value ≥4.75 had a shorter survival (p: 0.000). Multivariate analysis, which showed that survival was significantly related mNLR value > 0.42 and/or sNLR value > 4.75 (Odds Ratio (OR): 2.66, %95 CI, 1,65-4,3 p: 0.001), serum LDH > 210 (OR = 1.8, %95 CI, 1,33-2,46 p: 0.001) and age > 65 (OR = 1.9, %95 CI, 1,41-2,55 p = 0.001). Conclusion: sNLR and mNLR may act as a simple, useful, and cost-effective prognostic factor in patients with MPE. Furthermore, these results may serve as the cornerstone of further research into the mNLR in the future. Although further studies are required to generalize our results, this information will benefit clinicians and patients in determining the most appropriate therapy for patients with MPE.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Wei Kit Chee ◽  
Nor Azowa Ibrahim ◽  
Norhazlin Zainuddin ◽  
Mohd Faizal Abd Rahman ◽  
Buong Woei Chieng

Poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends were prepared via melt blending technique. Glycidyl methacrylate (GMA) was added as reactive compatibilizer to improve the interfacial adhesion between immiscible phases of PLA and PCL matrices. Tensile test revealed that optimum in elongation at break of approximately 327% achieved when GMA loading was up to 3wt%. Slight drop in tensile strength and tensile modulus at optimum ratio suggested that the blends were tuned to be deformable. Flexural studies showed slight drop in flexural strength and modulus when GMA wt% increases as a result of improved flexibility by finer dispersion of PCL in PLA matrix. Besides, incorporation of GMA in the blends remarkably improved the impact strength. Highest impact strength was achieved (160% compared to pure PLA/PCL blend) when GMA loading was up to 3 wt%. SEM analysis revealed improved interfacial adhesion between PLA/PCL blends in the presence of GMA. Finer dispersion and smooth surface of the specimens were noted as GMA loading increases, indicating that addition of GMA eventually improved the interfacial compatibility of the nonmiscible blend.


2017 ◽  
Vol 43 (4) ◽  
pp. 281-288 ◽  
Author(s):  
Catherine Rachel Morgan ◽  
Hanhua Liu

BackgroundReducing unplanned pregnancy in Scotland is a key government objective. Long-acting reversible contraception (LARC) is a cost-effective way to reduce unintended pregnancy. Abortion and teenage pregnancy rates are highest in the most deprived areas. One possible explanation could be contraceptive prescribing inequality. This study examined the relationship between area deprivation measured by the Scottish Index of Multiple Deprivation and LARC prescription.MethodsUsing Scottish electronic prescribing data from primary care and sexual and reproductive health clinics, this study analysed female Lothian residents with a valid postcode aged 16–49 years who received a contraceptive prescription from 1 April 2012 to 31 March 2014. Prescription of LARC (intrauterine, implant or injectable contraceptive) compared with non-LARC (oral pill, patch, ring or diaphragm) was examined. Logistic regression was performed adjusting for age group and prescription location.ResultsA total of 90 150 women were included; 21.1% of prescriptions were LARC and 15.3% vLARC (intrauterine method or implant). Women residing in the most deprived quintile (Q1) and prescribed contraception received a significantly higher proportion of LARC than quintiles 2–5 (Q2–5). Odds ratios compared with Q1 were: Q2 0.86, Q3 0.77, Q4 0.59 and Q5 0.51. Women in quintile 1 were also significantly more likely to receive vLARC than quintiles 2–5.ConclusionWomen in the most deprived quintile in Lothian who are prescribed contraception are significantly more likely to receive LARC and vLARC compared with women in less deprived quintiles.


Sign in / Sign up

Export Citation Format

Share Document