Elastic networks of protein particles

This paper describes the formation and properties of protein particle suspensions. The protein particles were prepared by a versatile method based on quenching a phase-separating protein–polysaccharide mixture. Two proteins were selected, gelatin and whey protein. Gelatin forms aggregates by means of reversible physical bonds, and whey protein forms aggregates that can be stabilized by chemical bonds. Rheology and microscopy show that protein particles aggregate into an elastic particle gel for both proteins. Properties similar to model systems of synthetic colloidal particles were obtained using protein particle suspensions. This suggests that the behaviour of the particle suspensions is mainly governed by the mesoscopic properties of the particle networks and to a lesser extent on the molecular properties of the particle

Enzyme-induced Formation of ß-Lactoglobulin Fibrils by AspN Endoproteinase

This paper describes a low temperature, enzymatic route to induce fibrillar structures in a protein solution. The route comprises two steps. First, ß-lactoglobulin was hydrolyzed into peptides at pH 8 and 37°C with the enzyme AspN endoproteinase, which resulted in the formation of random aggregates. After hydrolysis, the pH was lowered to 2. As a result, long fibrillar aggregates were formed which was observed using transmission electron microscopy and Thioflavin T fluorescence measurements

The influence of water and glycerol addition on thermal processing, rheology and microstructure changes of potato starch

In the present paper the influence of glycerol and water addition to potato starch during thermo-mechanical treatment was observed. The shearing-heating treatment was realised on the new designed equipment ¿ Shear Cell ¿ based on the cone and plate rheometer device. The measurement of rheological changes during processing showed that water and glycerol addition lowered the shear stress and the shear rate values. Also the influence on intrinsic viscosity was observed: higher level of water and glycerol added, the lower values of intrinsic viscosity was observed. Microstructure changes during processing confirming these result

Understanding the interplay of cancer patients’ instrumental concerns and emotions

Objective 1) to assess patients’ descriptions of concerns, and 2) to inform a conceptual framework in which the impact of the nature of concerns on doctor-patient communication is specified. Methods Six focus groups were conducted with 39 cancer patients and survivors. In these focus groups participants were asked to describe their concerns during and after their illness. Results Concerns were described as instrumental concerns (e.g., receiving insufficient information) and emotions (e.g., sadness). Patients frequently explained their concerns as an interplay of instrumental concerns and emotions. Examples of the interplay were “receiving incorrect information” and “frustration”, and “difficulties with searching, finding and judging of information” and “fear”. Conclusion Instrumental concerns need to be taken into account in the operationalization of concerns in research. Based on the interplay, the conceptual framework suggests that patients can express instrumental concerns as emotions and emotions as instrumental concerns. Consequently, providers can respond with instrumental and emotional communication when patients express an interplay of concerns. Practice implications The results of this study can be used to support providers in recognizing concerns that are expressed by patients in consultations

Cultivation of shear stress sensitive and tolerant microalgal species in a tubular photobioreactor equipped with a centrifugal pump

The tolerance to shear stress of Tetraselmis suecica, Isochrysis galbana, Skeletonema costatum, and Chaetoceros muelleri was determined in shear cylinders. The shear tolerance of the microalgae species strongly depends on the strain. I. galbana, S. costatum, and C. muelleri exposed to shear stress between 1.2 and 5.4 Pa resulted in severe cell damage. T. suecica is not sensitive to stresses up to 80 Pa. The possibility to grow these algae in a tubular photobioreactor (PBR) using a centrifugal pump for recirculation of the algae suspension was studied. The shear stresses imposed on the algae in the circulation tubes and at the pressure side of the pump were 0.57 and 1.82 Pa, respectively. The shear stress tolerant T. suecica was successfully cultivated in the PBR. Growth of I. galbana, S. costatum, and C. muelleri in the tubular PBR was not observed, not even at the lowest pumping speed. For the latter shear sensitive strains, the encountered shear stress levels were in the order of magnitude of the determined maximum shear tolerance of the algae. An equation was used to simulate the effect of possible damage of microalgae caused by passages through local high shear zones in centrifugal pumps on the total algae culture in the PBR. This simulation shows that a culture of shear stress sensitive species is bound to collapse after only limited number of passages, confirming the importance of considering shear stress as a process parameter in future design of closed PBRs for microalgal cultivation

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