Infinitesimally small deformation which preserves geodesic lines

2020 ◽  
Author(s):  
T. Podousova ◽  
A. Ugol'nikov ◽  
V. Dumanska
Keyword(s):  
Small Deformation ◽  
Geodesic Lines

Mesoscopic gelation of chitosan and genipin at below critical concentrations

2017 ◽  
Author(s):  
Christoph Engwer ◽  
Ronja Loy ◽  
Ioannis S. Chronakis ◽  
Ana C. Mendes ◽  
Francisco M. Goycoolea
Keyword(s):  
Sol Gel ◽  
Crosslinking Agent ◽  
Small Deformation ◽  
Macroscopic Appearance ◽  
Critical Concentrations ◽  
Gelation Kinetics ◽  
Gardenia Jasminoides ◽  
Sol Gel Transition ◽  
Low Cytotoxicity ◽  
High Concentrations

Genipin is increasingly used as a crosslinking agent for chitosans due to its low cytotoxicity as a naturally occurring extract of the plant <i>Gardenia jasminoides</i>. Genipin reacts with the primary amino groups of chitosan to form blue hydrogels. We studied the gelation kinetics of different chitosans varying in their properties (molar mass 34 000-213 000 g mol<sup>-1</sup>, degree of acetylation 9-20%) and genipin in detail. We found that critical sol-gel transition times obtained from dynamic light scattering were in good agreement with the results obtained by small deformation oscillatory rheometry and microviscosimetry at high concentrations of chitosan. However, at below critical concentrations, we found a second regime of gelation that followed the same Ross-Murphy's gelation kinetics. The macroscopic appearance of these samples was a suspension of weak gel-like particles that were sensitive to mechanical forces. We believe that the material is a mesoscopic gel, as described for other polymers. To the best of our knowledge, this is the first time that this phenomenon has been described for the gelling system of chitosan and genipin.

Visualization of Enneper’s surface by line graphics

Filomat ◽  
2017 ◽  
Vol 31 (2) ◽  
pp. 387-405 ◽  
Author(s):  
Vesna Velickovic
Keyword(s):  
Minimal Surface ◽  
Graphical Representations ◽  
Lines Of Curvature ◽  
Geodesic Lines

Here we study Enneper?s minimal surface and some of its properties. We compute and visualize the lines of self-intersection, lines of intersections with planes, lines of curvature, asymptotic and geodesic lines of Enneper?s surface. For the graphical representations of all the results we use our own software for line graphics.

Experimental Study on Mix Ratio Design and Road Performance of Medium and Small Deformation Seamless Expansion Joints of Bridges

2021 ◽  
pp. 036119812098474
Author(s):  
Pengzhen Lu ◽  
Chenhao Zhou ◽  
Simin Huang ◽  
Yang Shen ◽  
Yilong Pan
Keyword(s):  
Traffic Safety ◽  
Performance Test ◽  
Asphalt Mixture ◽  
Small Deformation ◽  
Expansion Joint ◽  
Expansion Joints ◽  
Mixture Ratio ◽  
The Road ◽  
Marshall Test ◽  
Road Performance

Expansion joints are a weak and fragile part of bridge superstructure. The damage or failure of the expansion joint will lead to the decline of bridge durability and endanger the bridge structure and traffic safety. To improve the service life and performance of bridge expansion joints, the ideal method is to use seamless expansion joints. In this study, starting from the commonly used asphalt mixture gradation of seamless expansion joint, and taking into account the actual situation of bridge expansion joint structure and environment in China, the gradation and asphalt-aggregate ratio are preliminarily designed. Through a Marshall test, the corresponding asphalt mixture is evaluated and analyzed according to the stability, flow value, and void ratio, and the optimal gradation and asphalt-aggregate ratio are determined. Finally, the asphalt mixture is prepared with the mixture ratio design, and the test results of an immersion Marshall test, fatigue performance test, and full-scale test verify that the asphalt mixture meets the road performance requirements of seamless expansion joints. On the basis of the experimental data, the performance of large sample asphalt mixture is continuously tested, compared, and optimized. The results show that the asphalt mixture ratio designed is true and reliable, which can provide reference for the optimal design of seamless expansion joint filler.

scholarly journals Linear and Nonlinear Normal Interface Stiffness in Dry Rough Surface Contact Measured Using Longitudinal Ultrasonic Waves

2021 ◽  
Vol 11 (12) ◽  
pp. 5720
Author(s):  
Saeid Taghizadeh ◽  
Robert Sean Dwyer-Joyce
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Ultrasonic Wave ◽  
Bulk Material ◽  
Nonlinear Differential Equations ◽  
Small Deformation ◽  
Ultrasonic Waves ◽  
Solid Contact ◽  
Interfacial Stiffness ◽  
Linear And Nonlinear

When two rough surfaces are loaded together contact occurs at asperity peaks. An interface of solid contact regions and air gaps is formed that is less stiff than the bulk material. The stiffness of a structure thus depends on the interface conditions; this is particularly critical when high stiffness is required, for example in precision systems such as machine tool spindles. The rough surface interface can be modelled as a distributed spring. For small deformation, the spring can be assumed to be linear; whilst for large deformations the spring gets stiffer as the amount of solid contact increases. One method to measure the spring stiffness, both the linear and nonlinear aspect, is by the reflection of ultrasound. An ultrasonic wave causes a perturbation of the contact and the reflection depends on the stiffness of the interface. In most conventional applications, the ultrasonic wave is low power, deformation is small and entirely elastic, and the linear stiffness is measured. However, if a high-powered ultrasonic wave is used, this changes the geometry of the contact and induces nonlinear response. In previous studies through transmission methods were used to measure the nonlinear interfacial stiffness. This approach is inconvenient for the study of machine elements where only one side of the interface is accessible. In this study a reflection method is undertaken, and the results are compared to existing experimental work with through transmission. The variation of both linear and nonlinear interfacial stiffnesses was measured as the nominal contact pressure was increased. In both cases interfacial stiffness was expressed as nonlinear differential equations and solved to deduce the contact pressure-relative surface approach relationships. The relationships derived from linear and nonlinear measurements were similar, indicating the validity of the presented methods.

scholarly journals Nutritional and Rheological Features of Lentil Protein Isolate for Yoghurt-Like Application

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1692
Author(s):  
Theresa Boeck ◽  
Emanuele Zannini ◽  
Aylin W. Sahin ◽  
Juergen Bez ◽  
Elke K. Arendt
Keyword(s):  
Laser Scanning ◽  
Base Material ◽  
Small Deformation ◽  
Protein Isolate ◽  
Protein Supplementation ◽  
Water Holding Capacity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Deformation Analysis ◽  
Water Holding

The substitution of animal protein with proteins of plant origin is a viable way to decrease the negative impact caused by animal husbandry on the environment. Pulse consumption has been widely promoted as a nutritious contribution to protein supplementation. In this study, an emulsion of lentil (Lens culinaris) protein isolate is fermented with lactic acid bacteria (LAB) to manufacture a yoghurt alternative and the techno-functional properties compared to a dairy- and a soy-based product with similar protein contents. The yoghurt-like products are subjected to large and small deformation analysis, quantification of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP), water holding capacity tests, protein profile analysis and the gel structure is visualised by confocal laser scanning microscopy (CLSM). The lentil yoghurt alternative shows good water holding capacity, high firmness and consistency values in large deformation analysis, with cohesiveness and viscosity not significantly different from that of dairy yoghurt. The high gel strength and rigidity of the lentil yoghurt gels measured by small deformation analysis is well-reflected in the dense protein matrix in the CLSM graphs. FODMAP content of the lentil yoghurt is very low, making it suitable for consumption by irritable bowel syndrome (IBS) patients. Our results show that lentil protein isolate is an excellent base material for producing a plant-based yoghurt alternative.

scholarly journals Manipulation of the Glass Transition Properties of a High-Solid System Made of Acrylic Acid-N,N′-Methylenebisacrylamide Copolymer Grafted on Hydroxypropyl Methyl Cellulose

2021 ◽  
Vol 22 (5) ◽  
pp. 2682
Author(s):  
Nazim Nassar ◽  
Felicity Whitehead ◽  
Taghrid Istivan ◽  
Robert Shanks ◽  
Stefan Kasapis
Keyword(s):  
Glass Transition ◽  
Acrylic Acid ◽  
Methyl Cellulose ◽  
Small Deformation ◽  
Polymerization Reaction ◽  
Solid Matrix ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
High Solid ◽  
Hydroxypropyl Methyl Cellulose

Crosslinking of hydroxypropyl methyl cellulose (HPMC) and acrylic acid (AAc) was carried out at various compositions to develop a high-solid matrix with variable glass transition properties. The matrix was synthesized by the copolymerisation of two monomers, AAc and N,N′-methylenebisacrylamide (MBA) and their grafting onto HMPC. Potassium persulfate (K2S2O8) was used to initiate the free radical polymerization reaction and tetramethylethylenediamine (TEMED) to accelerate radical polymerisation. Structural properties of the network were investigated with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), modulated differential scanning calorimetry (MDSC), small-deformation dynamic oscillation in-shear, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results show the formation of a cohesive macromolecular entity that is highly amorphous. There is a considerable manipulation of the rheological and calorimetric glass transition temperatures as a function of the amount of added acrylic acid, which is followed upon heating by an extensive rubbery plateau. Complementary TGA work demonstrates that the initial composition of all the HPMC-AAc networks is maintained up to 200 °C, an outcome that bodes well for applications of targeted bioactive compound delivery.

scholarly journals Characters of irrelevant deformations

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Shouvik Datta ◽  
Yunfeng Jiang
Keyword(s):  
Deformation Parameter ◽  
Central Charge ◽  
Scaling Limit ◽  
Small Deformation ◽  
State Dependent ◽  
Dependent Change ◽  
Left And Right ◽  
Double Scaling Limit

Abstract We analyse the $$ T\overline{T} $$ T T ¯ deformation of 2d CFTs in a special double-scaling limit, of large central charge and small deformation parameter. In particular, we derive closed formulae for the deformation of the product of left and right moving CFT characters on the torus. It is shown that the 1/c contribution takes the same form as that of a CFT, but with rescalings of the modular parameter reflecting a state-dependent change of coordinates. We also extend the analysis for more general deformations that involve $$ T\overline{T} $$ T T ¯ , $$ J\overline{T} $$ J T ¯ and $$ T\overline{J} $$ T J ¯ simultaneously. We comment on the implications of our results for holographic proposals of irrelevant deformations.

scholarly journals Mechanics of moving defects in growing sheets: 3-d, small deformation theory

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Amit Acharya ◽  
Shankar C. Venkataramani
Keyword(s):  
Deformation Theory ◽  
Small Deformation

scholarly journals Impact of Type of Sugar Beet Pectin–Sodium Caseinate Interaction on Emulsion Properties at pH 4.5 and pH 7

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 631
Author(s):  
Zhang Juyang ◽  
Bettina Wolf
Keyword(s):  
Sugar Beet ◽  
Storage Period ◽  
Small Deformation ◽  
Sodium Caseinate ◽  
Ph Adjustment ◽  
Potential Value ◽  
Emulsifier System ◽  
Oil In Water ◽  
Droplet Sizes ◽  
The Mean

Equal parts of sugar beet pectin and sodium caseinate were interacted through electrostatic attraction, enzymatic crosslinking, and the Maillard reaction to prepare three oil-in-water emulsifier systems. Oil-in-water emulsions (10%) were processed via high shear overhead mixing at the natural pH of the emulsifier systems, followed by pH adjustment to pH 4.5 and pH 7. The emulsions were stable against coalescence, except for a slight increase in the mean droplet size for the enzymatic cross-liked emulsion at pH 4.5 over a 14-day storage period. This emulsion also showed the lowest absolute zeta (ζ)-potential value of near 30 mV. The Maillard interaction emulsifier system resulted in larger droplet sizes compared to the other two emulsifier systems. Small deformation oscillatory shear rheology assessment of the emulsion cream phases revealed an impact of the emulsifier system design at pH 4.5.

scholarly journals A Review on Microstructural Features and Mechanical Properties of Wheels/Rails Cladded by Laser Cladding

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 152
Author(s):  
Xinlin Wang ◽  
Lei Lei ◽  
Han Yu
Keyword(s):  
Mechanical Properties ◽  
Service Life ◽  
Process Optimization ◽  
Laser Cladding ◽  
Future Development ◽  
Heat Affected Zone ◽  
Small Deformation ◽  
Microstructural Characteristics ◽  
Low Input ◽  
Recent Developments

The service life of rails would be remarkably reduced owing to the increase of axle load, which can induce the occurrence of damages such as cracks, collapse, fat edges, etc. Laser cladding, which can enhance the mechanical properties of the rail by creating a coating, has received great attention in the area of the rails due to the attractive advantages such as low input heat, small heat-affected zone, and small deformation. In this paper, recent developments in the microstructural characteristics and mechanical properties of a cladded layer on the rail are reviewed. The method of process optimization for enhancing the properties of a cladded layer are discussed. Finally, the trend of future development is forecasted.

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