scholarly journals A Green Approach towards Native Collagen Scaffolds: Environmental and Physicochemical Assessment

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1597
Author(s):  
Mireia Andonegi ◽  
Ainhoa Irastorza ◽  
Ander Izeta ◽  
Sara Cabezudo ◽  
Koro de la Caba ◽  
...  
Keyword(s):  
Global Strategy ◽  
X Ray Diffraction ◽  
Collagen Scaffolds ◽  
Green Approach ◽  
Use Of Resources ◽  
Native Collagen ◽  
Physical Interactions ◽  
Porous Microstructures ◽  
The Impact ◽  
Compression Resistance

Native collagen scaffolds were prepared in this work, in which both materials and environmental approaches were considered with the aim of providing a global strategy towards more sustainable biomaterials. From the environmental perspective, it is worth mentioning that acid and enzymatic treatments have been avoided to extract collagen, allowing the reduction in the use of resources, in terms of chemicals, energy, and time, and leading to a low environmental load of this step in all the impact categories under analysis. With the incorporation of chitosan into the scaffold-forming formulations, physical interactions occurred between collagen and chitosan, but the native collagen structure was preserved, as observed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The incorporation of chitosan also led to more homogenous porous microstructures, with higher elastic moduli and compression resistance for both dry and hydrated scaffolds. Furthermore, hydrated scaffolds preserved their size and shape after some compression cycles.

scholarly journals 3D-Printed Mucoadhesive Collagen Scaffolds as a Local Tetrahydrocurcumin Delivery System

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1697
Author(s):  
Mireia Andonegi ◽  
Teresa Carranza ◽  
Alaitz Etxabide ◽  
Koro de la Caba ◽  
Pedro Guerrero
Keyword(s):  
3D Printing ◽  
Fibrillar Structure ◽  
3D Printer ◽  
X Ray Diffraction ◽  
Collagen Scaffolds ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Native Collagen ◽  
3D Printed ◽  
Physical Interactions

Native collagen doughs were processed using a syringe-based extrusion 3D printer to obtain collagen scaffolds. Before processing, the rheological properties of the doughs were analyzed to determine the optimal 3D printing conditions. Samples showed a high shear-thinning behavior, reported beneficial in the 3D printing process. In addition, tetrahydrocurcumin (THC) was incorporated into the dough formulation and its effect on collagen structure, as well as the resulting scaffold’s suitability for wound healing applications, were assessed. The denaturation peak observed by differential scanning calorimetry (DSC), along with the images of the scaffolds’ surfaces assessed using scanning electron microscopy (SEM), showed that the fibrillar structure of collagen was maintained. These outcomes were correlated with X-ray diffraction (XRD) results, which showed an increase of the lateral packaging of collagen chains was observed in the samples with a THC content up to 4%, while a higher content of THC considerably decreased the structural order of collagen. Furthermore, physical interactions between collagen and THC molecules were observed using Fourier transform infrared (FTIR) spectroscopy. Additionally, all samples showed swelling and a controlled release of THC. These results along with the mucoadhesive properties of collagen suggested the potential of these THC–collagen scaffolds as sustained THC delivery systems.

scholarly journals Experiences and impact of international medical volunteering: a multi-country mixed methods study

BMJ Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. e041599 ◽  
Author(s):  
Mary McCauley ◽  
Joanna Raven ◽  
Nynke van den Broek
Keyword(s):  
Low Income ◽  
Online Survey ◽  
Positive Impact ◽  
Healthcare Providers ◽  
International Medical ◽  
Middle Income ◽  
Use Of Resources ◽  
The Uk ◽  
Medical Volunteers ◽  
The Impact

ObjectiveTo assess the experience and impact of medical volunteers who facilitated training workshops for healthcare providers in maternal and newborn emergency care in 13 countries.SettingsBangladesh, Ghana, India, Kenya, Malawi, Namibia, Nigeria, Pakistan, Sierra Leone, South Africa, Tanzania, UK and Zimbabwe.ParticipantsMedical volunteers from the UK (n=162) and from low-income and middle-income countries (LMIC) (n=138).Outcome measuresExpectations, experience, views, personal and professional impact of the experience of volunteering on medical volunteers based in the UK and in LMIC.ResultsUK-based medical volunteers (n=38) were interviewed using focus group discussions (n=12) and key informant interviews (n=26). 262 volunteers (UK-based n=124 (47.3%), and LMIC-based n=138 (52.7%)) responded to the online survey (62% response rate), covering 506 volunteering episodes. UK-based medical volunteers were motivated by altruism, and perceived volunteering as a valuable opportunity to develop their skills in leadership, teaching and communication, skills reported to be transferable to their home workplace. Medical volunteers based in the UK and in LMIC (n=244) reported increased confidence (98%, n=239); improved teamwork (95%, n=232); strengthened leadership skills (90%, n=220); and reported that volunteering had a positive impact for the host country (96%, n=234) and healthcare providers trained (99%, n=241); formed sustainable partnerships (97%, n=237); promoted multidisciplinary team working (98%, n=239); and was a good use of resources (98%, n=239). Medical volunteers based in LMIC reported higher satisfaction scores than those from the UK with regards to impact on personal and professional development.ConclusionHealthcare providers from the UK and LMIC are highly motivated to volunteer to increase local healthcare providers’ knowledge and skills in low-resource settings. Further research is necessary to understand the experiences of local partners and communities regarding how the impact of international medical volunteering can be mutually beneficial and sustainable with measurable outcomes.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

scholarly journals The Search for Natural and Synthetic Inhibitors That Would Complement Antivenoms as Therapeutics for Snakebite Envenoming

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 451
Author(s):  
José María Gutiérrez ◽  
Laura-Oana Albulescu ◽  
Rachel H. Clare ◽  
Nicholas R. Casewell ◽  
Tarek Mohamed Abd Abd El-Aziz ◽  
...  
Keyword(s):  
Snake Venom ◽  
Serine Proteinase ◽  
Global Strategy ◽  
World Health ◽  
Wide Range ◽  
Variable Chemical ◽  
Snake Venom Metalloproteinase ◽  
Health Organization ◽  
The Impact ◽  
Natural And Synthetic

A global strategy, under the coordination of the World Health Organization, is being unfolded to reduce the impact of snakebite envenoming. One of the pillars of this strategy is to ensure safe and effective treatments. The mainstay in the therapy of snakebite envenoming is the administration of animal-derived antivenoms. In addition, new therapeutic options are being explored, including recombinant antibodies and natural and synthetic toxin inhibitors. In this review, snake venom toxins are classified in terms of their abundance and toxicity, and priority actions are being proposed in the search for snake venom metalloproteinase (SVMP), phospholipase A2 (PLA2), three-finger toxin (3FTx), and serine proteinase (SVSP) inhibitors. Natural inhibitors include compounds isolated from plants, animal sera, and mast cells, whereas synthetic inhibitors comprise a wide range of molecules of a variable chemical nature. Some of the most promising inhibitors, especially SVMP and PLA2 inhibitors, have been developed for other diseases and are being repurposed for snakebite envenoming. In addition, the search for drugs aimed at controlling endogenous processes generated in the course of envenoming is being pursued. The present review summarizes some of the most promising developments in this field and discusses issues that need to be considered for the effective translation of this knowledge to improve therapies for tackling snakebite envenoming.

scholarly journals Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1230
Author(s):  
Jessica Manzi ◽  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Domenico Corona ◽  
Arianna Massaro ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Reversible Capacity ◽  
Beta Phase ◽  
X Ray Diffraction ◽  
Positive Electrodes ◽  
Detailed Structural Analysis ◽  
Physico Chemical ◽  
Sodium Batteries ◽  
The Impact ◽  
First Time

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

A Method for Evaluating Intensity of Water Cavitation Peening Processing

2011 ◽  
Vol 675-677 ◽  
pp. 747-750
Author(s):  
B. Han ◽  
Dong Ying Ju ◽  
Xiao Guang Yu
Keyword(s):  
Residual Stress ◽  
Process Capability ◽  
Diffraction Method ◽  
Spring Steel ◽  
Bubble Collapse ◽  
Plastic Layer ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
Near Surface ◽  
The Impact

Water cavitation peening (WCP) with aeration, namely, a new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration a standard N-type almen strips of spring steel SAE 1070 was treated byWCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by means of the Almen-scale and X-ray diffraction method, respectively. The optimal fluxes of aeration and the optimal standoff distances were achieved. The maximum of arc height value reach around 150μm. The depth of plastic layer observed from the results of residual stresses is up to 150μm. The results verify the existence of macro-plastic strain in WCP processing. The distributions of residual stress in near-surface under different peening intensity can provide a reference for engineers to decide the optimal process conditions of WCP processing.

Cleaner Environment Approach by the Utilization of Low Calcium Wood Ash in Geopolymer Concrete

2021 ◽  
Author(s):  
Kadarkarai Arunkumar ◽  
Muthiah Muthukannan ◽  
Arunachalam Suresh Kumar ◽  
Arunasankar Chithambar Ganesh ◽  
Rangaswamy Kanniga Devi
Keyword(s):  
Fly Ash ◽  
Microstructural Characterization ◽  
Wood Ash ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
High Potassium ◽  
Waste Wood ◽  
Research Findings ◽  
Research Gap ◽  
The Impact

The waste disposal issues were the most severe problems that could cause global warming, which depletes the environment. The research hypothesis was to find the suitability and sustainability of utilizing the waste by-products in the invention of green geopolymer concrete to eliminate the tremendous effects caused by the wastes. Due to the increased demand for fly ash in recent years, the requirement of high alkaline activators, and elevated temperature for curing, there was a research gap to find an alternative binder. The novelty of this research was to utilize the waste wood ash, which is available plenty in nearby hotels and has an inbuilt composition of high potassium that can act as a self alkaline activator. Waste wood ash procured from the local hotels was replaced with fly ash by 0 to 100% at 10% intervals. The setting and mechanical characteristics were found on the prolonged ages to understand the influence of waste wood ash. Microstructural characterization was found using Scanning Electron Microscope and X-Ray Diffraction Analysis to define the impact of waste wood ash in the microstructure. The research findings showed that replacing 30% waste wood ash with fly ash attained better performance in setting properties and all mechanical parameters. The obtained optimum mix could provide the best alternative for fly ash in geopolymer to eliminate the economic thrust by the requirement of alkaline activators and deploy the environmental impact caused by the waste wood ash.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

scholarly journals A REVIEW: A GREEN APPROACH FOR THE SYNTHESIS OF SILVER NANOPARTICLES AND ITS ANTIBACTERIAL APPLICATIONS

2018 ◽  
Vol 11 (8) ◽  
pp. 74 ◽  
Author(s):  
Shyla Marjorie Haqq ◽  
Amit Chattree
Keyword(s):  
Silver Nanoparticles ◽  
Antimicrobial Properties ◽  
Nanoparticle Synthesis ◽  
Silver Ions ◽  
Multidrug Resistant ◽  
X Ray Diffraction ◽  
Green Approach ◽  
Transmission Electron ◽  
Uv Visible ◽  
Silver Nanoparticle Synthesis

  This review is based on the synthesis of silver nanoparticles (AgNPs) using a green approach which is biofabricated from various medicinal plants. AgNPs were prepared from the various parts of the plants such as the flowers, stems, leaves, and fruits. Various physiochemical characterizations were performed using the ultraviolet (UV)-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and energy dispersive spectroscopy. AgNPs were also used to inhibit the growth of bacterial pathogens and were found to be effective against both the Gram-positive and Gram-negative bacteria. For the silver to have antimicrobial properties, it must be present in the ionized form. All the forms of silver-containing compounds with the observed antimicrobial properties are in one way or another source of silver ions. Although the antimicrobial properties of silver have been known, it is thought that the silver atoms bind to the thiol groups in enzymes and subsequently leads to the deactivation of enzymes. For the silver to have antimicrobial properties, it must be present in the ionized form. The study suggested that the action of the AgNPs on the microbial cells resulted into cell lysis and DNA damage. AgNPs have proved their candidature as a potential antibacterial against the multidrug-resistant microbes. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape, and application. Silver nanoparticle synthesis and their application are summarized and critically discussed in this review.

scholarly journals Preparation and Characterization of Spherical Submicron CL-20 by Siphon Spray Refinement

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Jiangtao Xing ◽  
Weili Wang ◽  
Wenzheng Xu ◽  
Tianle Yao ◽  
Jun Dong ◽  
...  
Keyword(s):  
Impact Sensitivity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystal Forms ◽  
Refined Method ◽  
Diffraction Angle ◽  
Ultrasonic Assisted ◽  
The Impact ◽  
Thermal Stability Of

In order to improve the safety of hexanitrohexaazaisowurtzitane (CL-20), submicron CL-20 particles were prepared by a siphon ultrasonic-assisted spray refining experimental device. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), and the impact sensitivity of the samples was tested. The results show that the particle size of siphon-refined CL-20 is about 800 nm~1 μm, which is more smooth, mellow, and dense than that of CL-20 prepared by a traditional pressure-refined method. The peak diffraction angle of pressure- and siphon-refined CL-20 is basically the same as that of raw CL-20, and their crystal forms are ε type. The peak strength of pressure- and siphon-refined CL-20 decreased obviously. The apparent activation energy of pressure-refined CL-20 and siphon-refined CL-20 is 13.3 kJ/mol and 11.95 kJ/mol higher than that of raw CL-20, respectively. The thermal stability of CL-20 is improved. The activation enthalpy (ΔH#) is significantly higher than that of raw CL-20, and the characteristic drop is 70.4% and 82.7% higher than that of raw CL-20. The impact sensitivity of siphon-refined CL-20 is lower than that of pressure-refined CL-20, so the safety performance of an explosive is improved obviously.

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