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1.
Cardiovasc Eng Technol ; 15(4): 418-430, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38499933

RESUMEN

PURPOSE: In-vitro modelling can be used to investigate haemodynamics of arterial geometry and stent implants. However, in-vitro model fidelity relies on precise matching of in-vivo conditions. In pulsatile flow, velocity distribution and wall shear stress depend on compliance, and the Reynolds and Womersley numbers. However, matching such values may lead to unachievable tolerances in phantom fabrication. METHODS: Published Reynolds and Womersley numbers for 14 major arteries in the human body were determined via a literature search. Preference was given to in-vivo publications but in-vitro and in-silico values were presented when in-vivo values were not found. Subsequently ascending aorta and carotid artery case studies were presented to highlight the limitations dynamic matching would apply to phantom fabrication. RESULTS: Seven studies reported the in-vivo Reynolds and Womersley numbers for the aorta and two for the carotid artery. However, only one study each reported in-vivo numbers for the remaining ten arteries. No in-vivo data could be found for the femoral, superior mesenteric and renal arteries. Thus, information derived in-vitro and in-silico were provided instead. The ascending aorta and carotid artery models required scaling to 1.5× and 3× life-scale, respectively, to achieve dimensional tolerance restrictions. Modelling the ascending aorta with the comparatively high viscosity water/glycerine solution will lead to high pump power demands. However, all the working fluids considered could be dynamically matched with low pump demand for the carotid model. CONCLUSION: This paper compiles available human haemodynamic information, and highlights the paucity of information for some arteries. It also provides a method for optimal in-vitro experimental configuration.


Asunto(s)
Arterias , Modelos Cardiovasculares , Humanos , Arterias/fisiología , Hemodinámica , Adaptabilidad , Estrés Mecánico , Flujo Pulsátil , Velocidad del Flujo Sanguíneo , Simulación por Computador , Flujo Sanguíneo Regional , Arterias Carótidas , Rigidez Vascular
2.
J Mech Behav Biomed Mater ; 151: 106386, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38219431

RESUMEN

The course of the middle meningeal vessels can be traced through imprints on the inner table of the human neurocranium. It is as yet unexplored whether these notches lower the load-bearing capacity of the bone when compared to areas that are free of vascular imprints. Here, 310 temporo-parietal samples with and without vascular imprints, from 52 human Crosado-embalmed cadavers, were tested in a three-point bending setup with a half-cylindrical impactor (1 mm radius of curvature) contacting the sample at 11 m/s. The maximum forces before breaking, and the thicknesses of the samples, were statistically compared, including comparing the avascular group to several groups with vascular imprints of different orientations. Furthermore, the influence of sample length and impact location were investigated. To investigate structure and mechanical function of vascular imprints concomitantly, scanning electron microscopy was performed on selected samples in two different planes. The results showed that avascular samples were on average thicker (p < 0.001) and stronger (p ≤ 0.050) compared to samples with vascular imprints. When only thickness-matched samples were analysed, the observed maximum forces of vascular and avascular samples were statistically similar (p ≥ 0.531). Regarding the load-bearing capacity of samples with vascular imprints, it was irrelevant whether the imprint was placed parallel to and directly underneath the impactor, parallel to and offset from the impactor, or perpendicular to the impactor (p > 0.999). The overall results of this study were statistically unrelated to both sample length (p ≥ 0.720) and impact location (p > 0.999). Scanning electron microscopy revealed that vascular imprints are formed through a curve of the inner table. Perforating holes of the inner table are present in avascular areas, however, they are considerably larger in size and higher in number within vascular imprints. In conclusion, vascular imprints are formed through curving of the inner table. In numerical models of human head mechanics, vascular imprints can be accounted for through a simple thinning of the bone assuming the same load-bearing capacity as for the surrounding imprint-free areas.


Asunto(s)
Cabeza , Cráneo , Humanos , Cadáver
3.
PLoS One ; 16(2): e0246123, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33577565

RESUMEN

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.


Asunto(s)
Espiración , Terapia por Inhalación de Oxígeno/efectos adversos , Terapia por Inhalación de Oxígeno/métodos , Adulto , Pruebas Respiratorias/métodos , COVID-19/terapia , Cánula , Femenino , Humanos , Masculino , Microscopía por Video , Nariz/química , Respiración , Frecuencia Respiratoria
4.
Mater Sci Eng C Mater Biol Appl ; 109: 110562, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32229001

RESUMEN

In order to obtain bioactive bone-implant interfaces with enhanced osteogenic capacity, various approaches have been developed to modify surface physicochemical properties of bio-inert titanium and titanium alloys. One promising strategy involves fabricating highly ordered nanotubes (NT) on implant surfaces via electrochemical anodization. However, few studies have applied this technique to Ti-6Al-4V alloys most commonly adopted for the fabrication of osteo-integrated surfaces on orthopedic implants. In this study, we investigated the influence of electrolyte hydrodynamics to NT fabrication on Ti-6Al-4V in ethylene glycol based electrolyte and evaluated the osteogenic differentiation capacity of human mesenchymal stromal cells (hMSCs) on different diameter NT surfaces. Computational Fluid Dynamics (CFD) analysis was used to simulate electrolyte flow profiles under various stirring conditions (e.g. stirrer bar location and flow direction) and their correlation to NT formation. Polished Ti-6Al-4V disks (240 grit) were anodized at 20 and 40 V under optimal electrolyte flow conditions for comparison of NT diameter-controlled osteogenic differentiation and mineralization potential of hMSCs over 21 days culture in osteogenic media. Ti-6Al-4V surfaces anodized with 20 and 40 V resulted with NTs diameter approx. 39 and 83 nm, respectively. Electrolyte hydrodynamics (flow profile) significantly influenced the uniformity of NT formation. Here, a uniform velocity and shear stress profile at the surface promoted homogeneous NT growth, whereas large variation in either flow velocity or shear stress to the surface impaired mature NT formation. After 21 days of culture, fluorescence staining demonstrated significantly greater osteocalcin and osteopontin expression, and increased mineralized deposits (xylenol orange staining) on fluctuating NT surfaces anodized under 20 V (Ø 39 nm) relative to flat NT layer anodized with 40 V (Ø 83 nm) and polished controls. This study provides a systematic investigation of NT formation with respect to the electrolyte hydrodynamic effects to NT growth on Ti-6Al-4V alloys, demonstrating the feasibility of a one-step anodization process for generating uniform NT under optimal hydrodynamics. Optimized wavy micro-/nano-topography with Ø 39 nm NT stimulated osteogenic differentiation capacity of hMSCs on Ti-6Al-4V alloys and confirmed the potential application of anodization to improve osteo-integrative surfaces in orthopedic implants.


Asunto(s)
Diferenciación Celular , Células Madre Mesenquimatosas/metabolismo , Nanotubos/química , Osteogénesis , Titanio/química , Aleaciones , Humanos , Hidrodinámica , Células Madre Mesenquimatosas/citología
5.
N Z Vet J ; 68(2): 107-111, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31647882

RESUMEN

Aim: To estimate, ex vivo, the torque required to cause vertebral dislocation of cattle tails.Methods: Five tails from dairy cows, severed at the junction between the sacrum and the first caudal vertebra, were sourced from a slaughterhouse. Within 2 hours of slaughter, the severed end of each tail was clamped in a vice and a steel collar was placed halfway along the tail. A torque wrench was attached to the steel collar, which was then rotated to produce an audible and palpable vertebral dislocation, and the torque at the time of the break was recorded.Results: The maximum torque required to break a tail was 20 Nm, the minimum was 9.8 Nm, and the uncertainty was 4.9 Nm.Conclusion: The torque required to break a cow's tail is unlikely to be applied accidentally if cattle are handled following recommended best practice. Thus if cattle on a farm can be shown to have broken tails due to manipulation by farm staff, cattle handling is not meeting the recommended best practice of the New Zealand Dairy Cattle Code of Welfare.


Asunto(s)
Bovinos/lesiones , Fracturas Óseas , Cola (estructura animal)/lesiones , Bienestar del Animal , Animales , Fenómenos Biomecánicos , Cadáver , Torque
6.
Cardiovasc Eng Technol ; 11(1): 14-23, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31820351

RESUMEN

PURPOSE: Fabrication of a suitable flow model or phantom is critical to the study of biomedical fluid dynamics using optical flow visualization and measurement methods. The main difficulties arise from the optical properties of the model material, accuracy of the geometry and ease of fabrication. METHODS: Conventionally an investment casting method has been used, but recently advancements in additive manufacturing techniques such as 3D printing have allowed the flow model to be printed directly with minimal post-processing steps. This study presents results of an investigation into the feasibility of fabrication of such models suitable for particle image velocimetry (PIV) using a common 3D printing Stereolithography process and photopolymer resin. RESULTS: An idealised geometry of a cerebral aneurysm was printed to demonstrate its applicability for PIV experimentation. The material was shown to have a refractive index of 1.51, which can be refractive matched with a mixture of de-ionised water with ammonium thiocyanate (NH4SCN). The images were of a quality that after applying common PIV pre-processing techniques and a PIV cross-correlation algorithm, the results produced were consistent within the aneurysm when compared to previous studies. CONCLUSIONS: This study presents an alternative low-cost option for 3D printing of a flow phantom suitable for flow visualization simulations. The use of 3D printed flow phantoms reduces the complexity, time and effort required compared to conventional investment casting methods by removing the necessity of a multi-part process required with investment casting techniques.


Asunto(s)
Arterias Cerebrales/diagnóstico por imagen , Circulación Cerebrovascular , Hemodinámica , Aneurisma Intracraneal/diagnóstico por imagen , Fantasmas de Imagen , Impresión Tridimensional , Reología/instrumentación , Velocidad del Flujo Sanguíneo , Arterias Cerebrales/fisiopatología , Diseño de Equipo , Humanos , Hidrodinámica , Interpretación de Imagen Asistida por Computador , Aneurisma Intracraneal/fisiopatología , Valor Predictivo de las Pruebas , Refractometría , Reproducibilidad de los Resultados , Propiedades de Superficie
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2019: 4737-4740, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31946920

RESUMEN

Cardiovascular diseases (CVD) are the leading cause of death in the developed world and aortic aneurysm is a key contributor. Aortic aneurysms typically occur in the thoracic aorta and can extend into the descending aorta. The Frozen Elephant Trunk stent (FET) is one of the leading treatments for the aneurysms extending into the descending aorta. This study focuses on the in-vitro experimentation of a stented descending aorta, investigating the haemodynamics in a compliant phantom. A silicone phantom of the descending aorta was manufactured using a lost core casting method. A PVC stent was manufactured using the same mould core. Particle Image Velocimetry (PIV) was used for pulsatile studies, focusing specifically on the passive fixation at the distal end of the FET. The results showed an apparent expansion in the diastolic period that was identified to be a collapse in the lateral plane. Flow recirculation regions were identified during the collapse. The collapse was attributed to low upstream and high downstream pressures causing a vacuum effect. The findings may imply a potential risk introduced by the FET stent that requires further investigation.


Asunto(s)
Aorta Torácica/fisiología , Hemodinámica , Stents , Aneurisma de la Aorta Torácica/terapia , Humanos , Fantasmas de Imagen , Reología
8.
Int J Legal Med ; 131(5): 1193-1201, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28154922

RESUMEN

In an attempt to obtain a deeper understanding of the factors which determine the characteristics of expirated bloodstain patterns, the mechanism of formation of airborne droplets was studied. Hot wire anemometry measured air velocity, 25 mm from the lips, for 31 individuals spitting, coughing and blowing. Expirated stains were produced by the same mechanisms performed by one individual with different volumes of a synthetic blood substitute in their mouth. The atomization of the liquid at the lips was captured with high-speed video, and the resulting stain patterns were captured on paper targets. Peak air velocities varied for blowing (6 to 64 m/s), spitting (1 to 64 m/s) and coughing (1 to 47 m/s), with mean values of 12 m/s (blowing), 7 m/s (spitting) and 4 m/s (coughing). There was a large (55-65%) variation between individuals in air velocity produced, as well as variation between trials for a single individual (25-35%). Spitting and blowing involved similar lip shapes. Blowing had a longer duration of airflow, though it is not the duration but the peak velocity at the beginning of the air motion which appears to control the atomization of blood in the mouth and thus stain formation. Spitting could project quantities of drops at least 1600 mm. Coughing had a shorter range of near 500 mm, with a few droplets travelling further. All mechanisms could spread drops over an angle >45°. Spitting was the most effective for projecting drops of blood from the mouth, due to its combination of chest motion and mouth shape producing strong air velocities. No unique method was found of inferring the physical action (spitting, coughing or blowing) from characteristics of the pattern, except possibly distance travelled. Diameter range in expirated bloodstains varied from very small (<1 mm) in a dense formation to several millimetres. No unique method was found of discriminating expirated patterns from gunshot or impact patterns on stain shape alone. Only 20% of the expirated patterns produced in this study contained identifiable bubble rings or beaded stains.


Asunto(s)
Manchas de Sangre , Espiración , Medicina Legal/métodos , Movimientos del Aire , Tos , Humanos , Modelos Biológicos , Reología
9.
Ann Biomed Eng ; 44(10): 3007-3019, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27059224

RESUMEN

Nasal high flow (NHF) therapy is used to treat a variety of respiratory disorders to improve patient oxygenation. A CO2 washout mechanism is believed to be responsible for the observed increase in oxygenation. In this study, experimentally validated Computational Fluid Dynamics simulations of the CO2 concentration within the upper airway during unassisted and NHF assisted breathing were undertaken with the aim of exploring the existence of this washout mechanism. An anatomically accurate nasal cavity model was generated from a CT scan and breathing was reproduced using a Fourier decomposition of a physiologically measured breath waveform. Time dependent CO2 profiles were obtained at the entrance of the trachea in the experimental model, and were used as simulation boundary conditions. Flow recirculation features were observed in the anterior portion of the nasal cavity upon application of the therapy. This causes the CO2 rich gas to vent from the nostrils reducing the CO2 concentration in the dead space and lowering the inspired CO2 volume. Increasing therapy flow rate increases the penetration depth within the nasal cavity of the low CO2 concentration gas. A 65% decrease in inspired CO2 was observed for therapy flow rates ranging from 0 to 60 L min(-1) supporting the washout mechanism theory.


Asunto(s)
Dióxido de Carbono/metabolismo , Oxigenoterapia Hiperbárica , Modelos Biológicos , Cavidad Nasal/metabolismo , Tráquea/metabolismo , Adulto , Humanos , Masculino , Cavidad Nasal/fisiopatología , Tráquea/fisiopatología
10.
Int J Legal Med ; 130(2): 563-8, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25773915

RESUMEN

Blood expirated from the nose may leave a characteristic bloodstain at a crime scene which can provide important clues for reconstructing events during a violent assault. Little research has been done on the typical velocities, trajectories and size distribution that can be expected from expirated blood. An experimental fluid dynamics technique known as stereoscopic particle image velocimetry is used in this work to obtain the air velocity field inside and outside the nostrils during exhalation. A numerical model was then used to compute the trajectory of blood drops of 0.5 and 2 mm. The drops were tracked until ground plane impact below the nostril exit. Three heights were investigated, 1.5, 1.6 and 1.7 m. For an expiration flow rate of 32 l/min in vivo, there is a maximum exit velocity from the nostril of approximately 4 m/s, with a 0.5 m/s difference between nostrils. After the drops have traversed the distances investigated, drops of 0.5 and 2 mm in diameter from both nostrils are at a similar velocity. This implies that the gravitational acceleration after the drops leave the jet has the most influence on velocity. It is however shown that exit velocity does affect impact location. Drop size affects both impact location and impact velocity. An increase in height increases the distance traversed. Compared to the 2-mm drop, the 0.5 mm had a lower impact velocity, but its impact location in the ground plane was further from the nostril exit. Understanding the physics of expirated blood flight allows better interpretation of expirated stains at crime scenes.


Asunto(s)
Manchas de Sangre , Nariz , Reología , Simulación por Computador , Ciencias Forenses , Humanos , Modelos Biológicos
11.
Forensic Sci Int ; 246: 104-9, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25485950

RESUMEN

One hypothesis for the physical mechanism responsible for backspatter during cranial gunshot wounding is that air is ejected by the collapse of the temporary cavity formed around the bullet path. Using bovine and ovine heads and simulant materials, evidence of this ejection was sought by measuring the velocity of the air that was drawn in and ejected from the cavity in front of the wound channel after bullet impact. A laminar flow of fog-laden air was arranged in front of the wound channel and two high speed cameras recording at 30,000 frames/second captured the air motion. All samples were shot with standard 9 mm × 19 mm FMJ ammunition. Different concentrations of ballistic gelatine were used to characterize the effect of elasticity of the material on the velocity of the air. Fresh bovine and ovine heads were shot with the same experimental set up to investigate if there was induction of air into, and ejection of air from the entrance wounds. The results show, for the first time, that the temporary cavity does eject air in gelatine. The velocity of in-drawn air for 3, 5 and 10% concentration of gelatine was 81, 76 and 65 m/s respectively and the velocity of ejected air for 5 and 10% concentration of gelatine were 43 and 72 m/s respectively. The results show that when the concentration of gelatine is increased, the velocity of the air drawn into the cavity decreases and the velocity of the ejected air increases. However, no ejection was observed in 3% gelatine, ovine or bovine heads. Although ejection of air was not observed, ejection of brain from the wound channel was seen. Using the velocity of the ejected brain, the minimum intracranial pressure required to eject the brain tissue was estimated to be 712 kPa and 468 kPa for the sheep and bovine heads respectively.


Asunto(s)
Aire , Traumatismos Penetrantes de la Cabeza/patología , Heridas por Arma de Fuego/patología , Animales , Encéfalo/patología , Bovinos , Balística Forense , Patologia Forense , Gelatina , Presión Intracraneal , Modelos Animales , Modelos Biológicos , Ovinos
12.
Forensic Sci Int ; 245: 107-20, 2014 12.
Artículo en Inglés | MEDLINE | ID: mdl-25447183

RESUMEN

Bloodstain Pattern Analysis (BPA) provides information about events during an assault, e.g. location of participants, weapon type and number of blows. To extract the maximum information from spatter stains, the size, velocity and direction of the drop that produces each stain, and forces acting during flight, must be known. A numerical scheme for accurate modeling of blood drop flight, in typical crime scene conditions, including droplet oscillation, deformation and in-flight disintegration, was developed and validated against analytical and experimental data including passive blood drop oscillations, deformation at terminal velocity, cast-off and impact drop deformation and breakup features. 4th order Runge-Kutta timestepping was used with the Taylor Analogy Breakup (TAB) model and Pilch and Erdman's (1987) expression for breakup time. Experimental data for terminal velocities, oscillations, and deformation was obtained via digital high-speed imaging. A single model was found to describe drop behavior accurately in passive, cast off and impact scenarios. Terminal velocities of typical passive drops falling up to 8m, distances and times required to reach them were predicted within 5%. Initial oscillations of passive blood drops with diameters of 1mm

Asunto(s)
Movimientos del Aire , Manchas de Sangre , Modelos Estadísticos , Fenómenos Biofísicos , Medicina Legal/métodos , Humanos
13.
Forensic Sci Int ; 228(1-3): 75-82, 2013 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-23597743

RESUMEN

Passive dripping, the slow dripping of blood under gravity, is responsible for some bloodstains found at crime scenes, particularly drip trails left by a person moving through the scene. Previous work by other authors has established relationships, under ideal conditions, between the size of the stain, the number of spines and satellite stains, the roughness of the surface, the size of the blood droplet and the height from which it falls. To apply these relationships to infer the height of fall requires independent knowledge of the size of the droplet. This work aims to measure the size of droplets falling from objects representative of hand-held weapons. Pig blood was used, with density, surface tension and viscosity controlled to fall within the normal range for human blood. Distilled water was also tested as a reference. Drips were formed from stainless steel objects with different roughnesses including cylinders of diameter between 10 and 100 mm, and flat plates. Small radius objects including a knife and a wrench were also tested. High speed images of the falling drops were captured. The primary blood drop size ranged from 4.15±0.11 mm up to 6.15±0.15 mm (depending on the object), with the smaller values from sharper objects. The primary drop size correlated only weakly with surface roughness, over the roughness range studied. The number of accompanying droplets increased with the object size, but no significant correlation with surface texture was observed. Dripping of blood produced slightly smaller drops, with more accompanying droplets, than dripping water.


Asunto(s)
Manchas de Sangre , Sangre , Gravitación , Armas , Animales , Biofisica , Medicina Legal , Modelos Animales , Fotograbar , Propiedades de Superficie , Porcinos , Agua
14.
Solid State Nucl Magn Reson ; 5(1): 133-43, 1995 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-8748651

RESUMEN

Results from 29Si, 23Na and 7Li magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, 7Li NMR relaxation and electrical conductivity in a series of [Li(1-x).Nax]2O.2SiO2 (disilicate) glasses are used to investigate the mixed-alkali effect. From the 29Si NMR spectra there is relatively little change of the network with alkali composition. 23Na and 7Li NMR linewidths and shifts change continuously as a function of composition, indicating that the alkali ions are intimately and uniformly mixed rather than separated into lithium and sodium-rich domains. The activation energy from electrical conductivity shows a distinct maximum at the central composition (x = 0.5), whereas the local activation energy for lithium motion determined from NMR shows only a smaller but monotonic increase as the lithium-content decreases.


Asunto(s)
Vidrio/química , Espectroscopía de Resonancia Magnética , Conductividad Eléctrica
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