The dynamic oscillatory rheological properties of hen’s egg white proteins using various enzymes

Reliability of Flip-Chip Ball Grid Array (FC-BGA) package greatly depends on the mechanical properties of underfill material. In the package with Ultra Low-k (ULK) die and high-lead solder bumps, low glass transition temperature (Tg) and low elastic modulus (E) are effective for ULK delaminations. However, same properties are not enough for the package with lead-free solder bumps. The lead-free solder bumps are brittle and easily cracked without the support of underfill by thermal stress. To acquire the package reliability in the thermal cycle test, we noticed the viscoelastic property. Although developed underfill material having low storage and high loss modulus were tested in thermal cycle, neither delamination of ULK nor crack of solder bump occurred until 1500 cycles. It was presumed that low storage modulus was effective for low thermal stress and high loss modulus induced relaxation of thermal stress at low temperature and during thermal cycle test. These results were verified by the simulation technique based on viscoelastic finite element method (FEM) analysis with shift factors and relaxation modulus of underfill material. Low storage modulus and high loss modulus were presumably due to the content of low modulus material (elastomer) in underfill material. These results indicate that it is successfully to utilize the fabricated underfill material as a highly functional package having ULK die and lead-free bumps.

Dynamic properties of alumina hollow particle filled aluminum alloy A356 matrix syntactic foams

Numerous cell functions are accompanied by phenotypic changes in viscoelastic properties, and measuring them can help elucidate higher level cellular functions in health and disease. We present a high-throughput, simple and low-cost microfluidic method for quantitatively measuring the elastic (storage) and viscous (loss) modulus of individual cells. Cells are suspended in a high-viscosity fluid and are pumped with high pressure through a 5.8 cm long and 200 µm wide microfluidic channel. The fluid shear stress induces large, ear ellipsoidal cell deformations. In addition, the flow profile in the channel causes the cells to rotate in a tank-treading manner. From the cell deformation and tank treading frequency, we extract the frequency-dependent viscoelastic cell properties based on a theoretical framework developed by R. Roscoe [1] that describes the deformation of a viscoelastic sphere in a viscous fluid under steady laminar flow. We confirm the accuracy of the method using atomic force microscopy-calibrated polyacrylamide beads and cells. Our measurements demonstrate that suspended cells exhibit power-law, soft glassy rheological behavior that is cell-cycle-dependent and mediated by the physical interplay between the actin filament and intermediate filament networks.

A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

Boza is a beverage produced by lactic acid bacteria (LAB) and yeast, which affects rheological properties. In the present study, boza samples collected from a local market were characterized with reference to microbiological and rheological approaches. The boza samples were characterized with respect to their microbiological population, i.e. the numbers of LAB and yeast. The numbers of LAB and yeast were found to range from 2.88 × 106 to 2.06 × 1010 CFU/mL and from 3.71 × 103 to 9.40 × 105 CFU/mL, respectively. Their steady and dynamic rheological properties were investigated within the temperature range of 0-50 °C. Apparent viscosity values (h) of the boza samples decreased with shear rate, indicating that the samples behaved as a pseudoplastic fluid. The Ostwald-de Waele model satisfactorily described (R2 > 0.99) the flow behavior of the samples at 5 and 20 °C. Storage modulus (G') values were higher than loss modulus (G''), indicating that boza samples had a solid-like structure. Temperature had a remarkable effect on the steady and dynamic properties of the samples; therefore, temperature sweep tests were also conducted to determine temperature dependency of the samples. The h50, G', and G'' values decreased with increase in temperature. The Arrhenius equation could be satisfactorily used to describe changes in these parameters depending on temperature. A modified Cox-Merz rule with shift factors ranging from 1.0 to 2.2 was successfully applied to put forward a relationship between steady shear and dynamic shear viscosity data.

As an excellent foaming agent, egg white protein (EWP) is always contaminated by egg yolk in the industrial processing, therefore, decreasing its foaming properties. The aim of this study was to simulate the industrial EWP (egg white protein with 0.5% w/w of egg yolk) and characterize their foaming and structural properties when hydrolyzed by two types of esterase (lipase and phospholipase A2). Results showed that egg yolk plasma might have been the main fraction, which led to the poor foaming properties of the contaminated egg white protein compared with egg yolk granules. After hydrolyzation, both foamability and foam stability of investigated systems thereof (egg white protein with egg yolk, egg white protein with egg yolk plasma, and egg white protein with egg yolk granules) increased significantly compared with unhydrolyzed ones. However, phospholipids A2 (PLP) seemed to be more effective on increasing their foaming properties as compared to those systems hydrolyzed by lipase (LP). The schematic diagrams of yolk fractions were proposed to explain the aggregation and dispersed behavior exposed in their changes of structures after hydrolysis, suggesting the aggregated effects of LP on yolk plasma and destructive effects of PLP on yolk granules, which may directly influence their foaming properties.

Optically clear pressure‐sensitive adhesive (OCA) possesses exceptional optical properties and exhibits pressure‐sensitive adhesion, making it widely utilized in the adhesive layers of various electronic display devices. However, the increasing popularity of foldable mobile phones in recent years has imposed new requirements on the overall performance of OCA. Conventional pressure‐sensitive adhesives can enhance recoverability through cross‐linking but often demonstrate inadequate adhesive strength. In this study, three long‐chain crosslinking agents (CL) were synthesized using hydroxyethyl acrylate (HEA), dicyclohexylmethane diisocyanate (HMDI), polypropylene glycol (PPG), polyether amine (PEA), and hydroxyl‐terminated polybutadiene (R45V). The long‐chain CL agent contains numerous flexible segments that improve the recovery capability of the OCA while maintaining a certain level of adhesion. The optical clear pressure‐sensitive adhesive, crosslinked by three flexible crosslinkers, exhibits a low glass transition temperature (−60 to −40°C) and a low storage modulus (<0.1 MPa), along with an appropriate 180° stripping force (6–8 N/25 mm). Optically transparent pressure‐sensitive adhesives demonstrate excellent recovery properties (>85%), high light transmittance (>92%), and exceptional flexibility. Moreover, compared to market products, the optically transparent pressure‐sensitive adhesive shows superior folding resistance (>100,000 times). This indicates its suitability for applications in flexible optical displays such as foldable mobile phones and wearable electronics.

The modulus E(t) variations were determined for natural Guayule rubber, natural Hevea rubber, and synthetic polyisoprene. This was done with unvulcanized samples, with and without carbon black; and with vulcanized samples, with and without carbon black. Using the time‐temperature superposition principle, the corresponding master curves were obtained. Using the procedure by Tobolsky and Murakami, a generalized Maxwell model was adjusted to each master curve. Finally, using the approximations due to Ferry and Williams and to Alfrey, the storage and loss modulus were obtained for each sample. It is shown that when unvulcanized Guayule rubber behaves very similar to synthetic polyisoprene; but having lower modulus, lower relaxation time, and lower storage modulus than Hevea. Vulcanized Guayule rubber can behave either very similar to Hevea rubber or present lower modulus, lower relaxation time, lower storage modulus, and higher loss modulus than Hevea; depending on the Guayule rubber vulcanizing system.

Functional Assessment of Decellularized Extracellular Matrix in Patients Undergoing LVAD Implantation

Rheological and dynamic-mechanical behavior of carbon nanotube/vinyl ester–polyester suspensions and their nanocomposites

Development of soy protein emulsion gels-based 3D printed dysphagia foods: Effects of the egg white protein supplementation

Enrichment of stirred yogurt with soluble dietary fiber from Pachyrhizus erosus L. Urban: Effect on syneresis, microstructure and rheological properties

Epoxy syntactic foams that are capable of withstanding use-temperatures in the range of 106 to 175°C were fabricated with DGEBA or novolac based epoxy resins and appropriate amine hardener materials. These foams were characterized for dynamic mechanical properties in single cantilever mode. The storage modulus, loss modulus and tan δ values were recorded over a wide temperature range. A typical density value of around 0.45 g/cm3 of the syntactic foams made respectively from a cycloaliphatic amine hardener, aromatic amine hardener-I, aromatic amine hardener-II recorded storage modulus (E′) values of 1354 MPa, 1500 MPa and 1530 MPa respectively and tan δ values of 0.0139, 0.0090, 0.01039 respectively at 30°C. The storage modulus values gradually decreased with increasing temperature while the loss modulus values showed corresponding gradual increase in the same temperature range. There is a steep variation in these values when the material softens in the vicinity of the glass transition temperature (Tg) indicating the upper temperature limits to which they can be put in use. The reduction in the storage modulus values with increasing temperature and the glass transition temperature values are characteristic of the resin/hardener systems as well as the curing/post curing cycles employed.

Development and characterization of acid-induced whey protein concentrate and egg white protein composite gel

Preparation of high internal phase emulsions based on high-temperature glycation-modified egg white protein: Structural characteristics, stability, and β-carotene bioavailability under multi-parameter regulation