Strong Biomimetic Hydroxyapatite Scaffolds

2006 ◽  
Vol 49 ◽  
pp. 148-152 ◽  
Author(s):  
Sylvain Deville ◽  
Eduardo Saiz ◽  
Ravi K. Nalla ◽  
Antoni P. Tomsia
Keyword(s):  
Porous Ceramic ◽  
Porous Scaffolds ◽  
Biomimetic Scaffolds ◽  
Lamellar Materials ◽  
Biomimetic Hydroxyapatite ◽  
Controlled Freezing ◽  
New Generation ◽  
Fundamental Limitation ◽  
Random Porosity ◽  
Better Than

Despite extensive efforts in the development of fabrication methods to prepare porous ceramic scaffolds for osseous tissue regeneration, all porous materials have a fundamental limitation- the inherent lack of strength associated with porosity. Shells (nacre), tooth and bone are frequently used as examples for how nature achieves strong and tough materials made out of weak components. So, the unresolved engineering dilemma is how to create a scaffold that is both porous and strong. The objective of this study was to mimic the architecture of natural materials in order to create a new generation of strong hydroxyapatite-based porous scaffolds. The porous inorganic scaffolds were fabricated by the controlled freezing of water-based hydroxyapatite (HA) slurries. The scaffolds obtained by this process have a lamellar architecture that exhibits similarities with the meso- and micro- structure of the inorganic component of nacre. Compressive strengths of 20 MPa were measured for lamellar scaffolds with densities of 32%, significantly better than for the HA with random porosity. In addition, the lamellar materials exhibit gradual fracture unlike conventional porous HA scaffolds. These biomimetic scaffolds could be the basis for a new generation of porous and composite biomaterials.

Finding the Right Problems: Some HREM Applications to Interfaces

1984 ◽  
Vol 42 ◽  
pp. 376-379
Author(s):  
D. Cherns
Keyword(s):  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Resolution Electron ◽  
Point To Point ◽  
The Right ◽  
New Generation ◽  
Better Than

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.

Masers as probes of the gas dynamics close to forming high-mass stars

2017 ◽  
Vol 13 (S336) ◽  
pp. 201-206 ◽  
Author(s):  
Luca Moscadelli ◽  
Alberto Sanna ◽  
Ciriaco Goddi
Keyword(s):  
Gas Dynamics ◽  
Very Long Baseline Interferometry ◽  
High Mass ◽  
Powerful Technique ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Massive Forming ◽  
Typical Distances ◽  
New Generation ◽  
Better Than

AbstractImaging the inner few 1000 AU around massive forming stars, at typical distances of several kpc, requires angular resolutions of better than 0″.1. Very Long Baseline Interferometry (VLBI) observations of interstellar molecular masers probe scales as small as a few AU, whereas (new-generation) centimeter and millimeter interferometers allow us to map scales of the order of a few 100 AU. Combining these informations all together, it presently provides the most powerful technique to trace the complex gas motions in the proto-stellar environment. In this work, we review a few compelling examples of this technique and summarize our findings.

scholarly journals Assessing the Current Generation of Tourniquets

2020 ◽  
Vol 185 (3-4) ◽  
pp. e377-e382
Author(s):  
Shimon Katsnelson ◽  
Jessie Oppenheimer ◽  
Rafi Gerrasi ◽  
Ariel Furer ◽  
Linn Wagnert-Avraham ◽  
...  
Keyword(s):  
Applied Pressure ◽  
Military Medicine ◽  
Pressure Profile ◽  
Strongly Correlated ◽  
Hemorrhage Control ◽  
Strong Negative Correlation ◽  
Life Saving ◽  
Significant Difference ◽  
New Generation ◽  
Better Than

Abstract Introduction Tourniquet application is an urgent life-saving procedure. Previous studies demonstrated several drawbacks in tourniquet design and application methods that limit their efficacy; among them, loose application of the device before windlass twisting is a main pitfall. A new generation of modern combat tourniquets was developed to overcome these pitfalls. The objective of this study was to assess the effectiveness of three new tourniquet designs: the CAT Generation 7 (CAT7), the SAM Extremity Tourniquet (SAM-XT), and the SOF Tactical Tourniquet Wide (SOFTT-W) as well as its correlation to the degree of slack. Materials and Methods The three tourniquet models were applied in a randomized sequence on a HapMed leg tourniquet trainer, simulating an above-the-knee traumatic amputation by 60 military medicine track cadets. Applied pressure, hemorrhage control status, time until the bleeding stopped, estimated blood volume loss, and slack were measured. Results The mean (±SD) pressure applied using the SAM-XT (186 mmHg ±63) or the CAT7 (175 mmHg ±79) was significantly higher compared to the pressure applied by the SOFTT-W (104 mmHg ±101, P < 0.017), with no significant difference between the first two (P > 0.05). Hemorrhage control rate was similar (P > 0.05) with SAM-XT (73.3%) and CAT7 (67.7%), and both were significantly better than the SOFTT-W (35%, P < 0.017). Slack was similar between CAT7 and SAM-XT (5.2 mm ± 3.4 vs. 5 mm ± 3.5, P > 0.05), yet significantly lower compared to the SOFTT-W (9 mm ± 5, P < 0.017). A strong negative correlation was found between slack and hemorrhage control rate (3.2 mm ± 1.5 mm in success vs. 10.5 mm ± 3.4 mm in failure, P < 0.001) and applied pressure (Pearson’s correlation coefficient of −0.83, P < 0.001). Conclusions Both SAM-XT and CAT7 demonstrated a better pressure profile and hemorrhage control rate compared to SOFTT-W, with no significant difference between the two. The better outcome measures were strongly correlated to less slack.

Minimum Zone Evaluation of Symmetry Error for Flatness to Flatness Based on the New Generation GPS

2013 ◽  
Vol 662 ◽  
pp. 887-891
Author(s):  
Qian Qian ◽  
Mei Fa Huang ◽  
Huan Yu Li
Keyword(s):  
Least Square Method ◽  
Mathematic Model ◽  
Least Square ◽  
Adaptive Genetic Algorithm ◽  
Machining Error ◽  
Minimum Zone ◽  
New Generation ◽  
Tolerance Method ◽  
The Mathematical Model ◽  
Better Than

Least square method (LSM) is the most popular method used to evaluate machining error nowadays. However, LSM is likely to overestimate the error value, therefore its solution is only approximate and rather than minimum. In order to obtain the minimum, we study the principle of the minimum zone tolerance method (MZT), analyze the characteristics of the new generation GPS, and give the minimum zone mathematic model of the symmetry error for flatness to flatness. For the purpose of optimizing the mathematical model, this paper describes the application of adaptive genetic algorithm to achieve the best estimation. Simultaneously, the process of optimization is realized by MALTAB. Finally, the experiment shows that the evaluation results of MZT is better than evaluation results of LSM.

The Analysis and Simulation of Stream Control Transmission Protocol

2013 ◽  
Vol 433-435 ◽  
pp. 1795-1799
Author(s):  
Hui Min Weng ◽  
Ming He Huang ◽  
Hao Wang ◽  
Chang Qiao Xu ◽  
Kai Liu
Keyword(s):  
Basic Structure ◽  
Transport Layer ◽  
Transmission Protocol ◽  
Stream Control Transmission Protocol ◽  
Concurrent Multipath Transfer ◽  
Multiple Paths ◽  
Transport Layer Protocol ◽  
Stream Control ◽  
New Generation ◽  
Better Than

Stream Control Transmission Protocol (SCTP) is a new generation of reliable transport layer protocol, unlike TCP, it has new features of multi-homing and multi-streaming, and has good scalability. SCTP is expected to replace TCP as the next generation of universal transport layer protocol. We introduce and analyze the basic structure and features of SCTP, introduce the related research of SCTP, including the implementation method of mobile SCTP and the Concurrent Multipath Transfer mechanism. Finally, compared and analyzed the performance of TCP, SCTP and SCTP-CMT by the ns-2 simulations, results show that in the case of multiple paths are available, the transmission performance of SCTP and SCTP-CMT are both better than TCP.

Natural compounds as light stabilizer for a starch-based biodegradable polymer

2014 ◽  
Vol 34 (5) ◽  
pp. 441-449 ◽  
Author(s):  
NadkaTz. Dintcheva ◽  
Francesco Paolo La Mantia ◽  
Rossella Arrigo
Keyword(s):  
Biodegradable Polymer ◽  
Natural Compounds ◽  
Mechanical Tests ◽  
Flavonoid Compound ◽  
Biodegradable Films ◽  
Biodegradable Film ◽  
Light Stabilizer ◽  
Agricultural Applications ◽  
New Generation ◽  
Better Than

Abstract The photooxidation behavior of a commercial starch-based biodegradable polymer, i.e., new generation Mater-Bi, loaded with natural stabilizers was investigated in consideration for outdoor agricultural applications. The photooxidation behavior of the biodegradable films was monitored mainly by mechanical tests and spectroscopic analysis. In order to formulate biodegradable films without any synthetic compounds, suitable for outdoor applications and with good photooxidation stability, antioxidants such as α-tocopherol and quercetin (Q) were considered. The results obtained using natural compounds were compared with those obtained by using a synthetic antioxidant and a light stabilizer. Among the investigated natural compounds, the flavonoid compound seemed to work better than the antioxidant and the improvement in the photooxidation behavior of the biodegradable film was very similar to that obtained using the synthetic light stabilizer. A flavonoid compound can be considered as an outstanding natural stabilizer to replace synthetic light stabilizers in the formulation of 100% natural compounds based films, suitable for outdoor applications.

scholarly journals Up-Cycling of LCD Glass by Additive Manufacturing of Porous Translucent Glass Scaffolds

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5083
Author(s):  
Arish Dasan ◽  
Paulina Ożóg ◽  
Jozef Kraxner ◽  
Hamada Elsayed ◽  
Elena Colusso ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Viscous Flow ◽  
Porous Ceramic ◽  
Porous Scaffolds ◽  
Organic Additives ◽  
Burn Out ◽  
Ceramic Components ◽  
High Transition ◽  
Manufacturing Technologies ◽  
Highly Porous

Additive manufacturing technologies, compared to conventional shaping methods, offer great opportunities in design versatility, for the manufacturing of highly porous ceramic components. However, the application to glass powders, later subjected to viscous flow sintering, involves significant challenges, especially in shape retention and in the achievement of a substantial degree of translucency in the final products. The present paper disclosed the potential of glass recovered from liquid crystal displays (LCD) for the manufacturing of highly porous scaffolds by direct ink writing and masked stereolithography of fine powders mixed with suitable organic additives, and sintered at 950 °C, for 1–1.5 h, in air. The specific glass, featuring a relatively high transition temperature (Tg~700 °C), allowed for the complete burn-out of organics before viscous flow sintering could take place; in addition, translucency was favored by the successful removal of porosity in the struts and by the resistance of the used glass to crystallization.

scholarly journals Low dislocation density, high power InGaN laser diodes

2004 ◽  
Vol 9 ◽  
Author(s):  
Piotr Perlin ◽  
M. Leszczyñski ◽  
P. Prystawko ◽  
P. Wisniewski ◽  
R. Czernetzki ◽  
...  
Keyword(s):  
Dislocation Density ◽  
High Power ◽  
Laser Diodes ◽  
Epitaxial Lateral Overgrowth ◽  
Homogeneous Distribution ◽  
Lateral Overgrowth ◽  
Low Dislocation Density ◽  
Bulk Gan ◽  
New Generation ◽  
Better Than

We used single crystals of GaN, obtained from high-pressure synthesis, as substrates for Metalorganics Vapor Phase Epitaxy growth of violet and UV laser diodes. The use of high-quality bulk GaN leads to the decrease of the dislocation density to the low level of 105 cm−2, i.e. two orders of magnitude better than typical for the Epitaxial Lateral Overgrowth laser structures fabricated on sapphire. The low density and homogeneous distribution of defects in our structures enables the realization of broad stripe laser diodes. We demonstrate that our laser diodes, having 15 μm wide stripes, are able to emit 1.3-1.9 W per facet (50% reflectivity) in 30 ns long pulses. This result, which is among the best ever reported for nitride lasers, opens the path for the development of a new generation of high power laser diodes.

New-Generation Pulse Oximetry in the Care of Critically Ill Patients

2005 ◽  
Vol 14 (1) ◽  
pp. 26-37 ◽  
Author(s):  
Karen K. Giuliano ◽  
Thomas L. Higgins
Keyword(s):  
Critical Care ◽  
Clinical Practice ◽  
Pulse Oximetry ◽  
Critically Ill Patients ◽  
Clinical Performance ◽  
Convincing Evidence ◽  
Generation Pulse ◽  
New Generation ◽  
Pulse Oximeters ◽  
Better Than

• Objective To review the published, peer-reviewed studies to date on use of the new-generation pulse oximeters, which are manufactured with algorithms to filter out patients’ body motions, and describe the application of new-generation pulse oximetry in clinical practice in critical care. • Methods MEDLINE was used to locate appropriate articles on pulse oximetry for the years 1995 to 2003. Each article was examined for scientific merit, content, and applicability to clinical practice. • Results A total of 17 relevant articles on the clinical performance of the new-generation pulse oximeters were reviewed, and the data were organized into a table. • Conclusions The combination of studies done in both clinical and laboratory settings did not provide any strong and convincing evidence that the performance of any single new-generation device was superior to that of any other new-generation device. However, the clinical performance of all the new-generation pulse oximetry devices was better than that of earlier devices.

Osteogenesis of Porous Bioceramics Scaffolds Consisted of Hydroxyapatite Spherules after Implanted in Different Non-Osseous Sites

2009 ◽  
Vol 610-613 ◽  
pp. 1335-1338 ◽  
Author(s):  
Yu Yuan ◽  
Peng Huang ◽  
Qian Peng ◽  
Cong Zhang ◽  
Jie Weng
Keyword(s):  
Porous Structure ◽  
Bone Growth ◽  
Abdominal Cavity ◽  
Sol Gel ◽  
Porous Scaffolds ◽  
3 Dimensional ◽  
Porous Bioceramic ◽  
Sol Gel Process ◽  
The Relationship ◽  
Better Than

The interconnected porous scaffolds are crucial to support the attachment, differentiation, proliferation of cells so to construct 3-dimensional (3-D) tissues. Up to now, there are several approaches to prepare porous scaffolds. In our experiments, we designed a novel porous bioceramic scaffold, called the hydroxyapatite (HA) spherule scaffold, by accumulating HA spherules in an HA porous tube to establish an interconnected porous structure which can be reconstructed exactly. The porous HA tube was manufactured by polymer sponge template while HA spherules were prepared by sol-gel process. In the animal experiment, the HA spherule scaffolds were implanted at 2 different non-osseous sites such as muscle and abdominal cavity in dogs. The new bone growth was investigated after six months. The preliminary results demonstrated that the proliferation of osteocytes on the scaffolds in muscle was obviously better than in abdominal cavity, and about ten times more blood vessels (BVs) were appeared in the former site than those in the latter site. This study presents an alternative way to reveal the relationship between the porous structure of scaffolds and ectopia bone growth because the interconnection and porosity can be controlled easily by the size and porosity of HA spherules.

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