Modelling of the response of acoustic piezoelectric resonators in biosensor applications-Part 1: The general theoretical analysis

Acoustic piezoelectric resonators are widely used as precise analytical chemistry tools for the realtime monitoring of a negligibly small amount of surface-attached mass of biological components, in particular, in environmental biosensor measurements. The surface acoustic wave (SAW)-based sensors and the quartz crystal microbalance (QCM) compared in our work belong to the leading group due to their considerable advantages. These piezoelectric resonators are considered now as high-resolution analytical tools allowing researchers to discriminate between components due to the selective polymer coating on the resonator surface. The gravimetrical measurements performed with the SAW-based or QCM sensors provide the experimental data with high precision for the detection of surface mass for the thin adsorbed layer rigidly attached to the oscillator surface. The new challenge is the analysis of soft and biological materials, where the viscous losses of energy can essentially influence measured characteristics. Modelling is the important part of the analysis allowing researchers to quantify the results of the experiments. The present work provides a general theory of SH-SAW devices probing soft and biological materials. The results are compared with QCM-D operated in liquid media

Nonresonant high frequency excitation of mechanical vibrations in graphene based nanoresonator

We theoretically analyse the dynamics of a suspended graphene membrane which is in tunnel contact with grounded metallic electrodes and subjected to ac-electrostatic potential induced by a gate electrode. It is shown that for such system the retardation effects in the electronic subsystem generate an effective pumping for the relatively slow mechanical vibrations if the driving frequency exceeds the inverse charge relax- ation time. Under this condition there is a critical value of the driving voltage ampli- tude above which the pumping overcomes the intrinsic damping of the mechanical resonator leading to a mechanical instability. This nonresonant instability is saturated by nonlinear damping and the system exhibits self-sustained oscillations of relatively large amplitude.Comment: Major revisio

ИДЕЯ УНИВЕРСИТЕТА В ЦИФРОВОМ ОБЩЕСТВЕ

Purpose. The article traces the dynamics of the “evolution” of the idea of university over several centuries and analyzes the sociocultural transformations taking place with the university in the modern digital society.Methodology. The basis of the research are methods of theoretical generalizations, methods of classification, comparative and systemic methods.Results. The generalization of views on university made it possible to distinguish two stages in the dynamics of the sociocultural role of it as a social institution: the stage of cultural orientation of the idea of university education and the stage of professional orientation. The sociocultural foundations of the first stage were the understanding of university as a social institution, the main mission of which is the formation of ideological attitudes that would be focused on humanistic and universal principles of life. University, in this case, acts as a translator of culture, its attitudes and values. The stage of vocational orientation is characterized by the understanding of the university as a professional educational institution that does not form the worldview foundations of a person. The university is a communication platform, a network organization, providing educational services - knowledge free from any philosophical, moral and ideological burdens. At this stage, the university provides private utilitarian knowledge, does not lead to a common understanding and experience of the unity of knowledge. A new economic model of the university comes, based on the transfer of pragmatic, narrowly professional, in-demand knowledge, which is assigned the status of goods and services.Practical implications. The results of the research can be applied in the field of socio-economic forecasting in the field of higher education.Цель. В статье прослежена динамика «эволюционирования» идеи университета на протяжении нескольких столетий его развития и проанализированы происходящие с университетом в современном цифровом обществе социокультурные трансформации.Метод или методология проведения работы. Основу исследования составляют методы теоретических обобщений, приемы классификации, компаративистский и системный методы.Результаты. Обобщение взглядов на университет позволило выделить два этапа в динамике социокультурной роли университета как социального института: этап культурной ориентации идеи университетского образования и этап профессиональной ориентации идеи университета. Социокультурными основаниями первого этапа стало понимание университета как социального института, основной миссией которого становится формирование мировоззренческих установок, которые были бы ориентированы на гуманистические и общечеловеческие принципы бытия. Университет, в этом случае выступает в качестве транслятора культуры, ее установок и ценностей. Этап профессиональной ориентации характеризуется пониманием университета как профессионального образовательного учреждения, не формирующего мировоззренческие основания человека. Университет представляет собой коммуникативную площадку, сетевую организацию, предоставляя образовательные услуги – знания, свободные от каких-либо философских, моральных и идеологических нагрузок. Университет на данном этапе дает частные утилитарные знания, не приводит к общему пониманию и переживанию единства знания. Приходит новая экономическая модель университета, основанная на передаче прагматичных, узкопрофессиональных, востребованных знаний, которым присваивается статус товара и услуги.Область применения результатов. Результаты исследования могут быть применены в сфере социально-экономического прогнозирования в области высшего образования.

Development of a combined surface plasmon resonance/surface acoustic wave device for the characterization of biomolecules

It is known that acoustic sensor devices, if operated in liquid phase, are sensitive not just to the mass of the analyte but also to various other parameters, such as size, shape, charge and elastic constants of the analyte as well as bound and viscously entrained water. This can be used to extract valuable information about a biomolecule, particularly if the acoustic device is combined with another sensor element which is sensitive to the mass or amount of analyte only. The latter is true in good approximation for various optical sensor techniques. This work reports on the development of a combined surface plasmon resonance/surface acoustic wave sensor system which is designed for the investigation of biomolecules such as proteins or DNA. Results for the deposition of neutravidin and DNA are reported

Pleading Securities Fraud

Hyaluronan based hydrogel coatings can mimic extracellular matrix components and incorporate growth factors that can be released during a progressive degradation while new tissue regenerates. This paper describes a structural characterization of a hydrogel coating made of modified hyaluronan polymers and how these coatings interact with bone morphogenetic protein-2 (BMP-2). Quartz crystal microbalance and neutron reflectivity measurements were used for in-situ, real-time measurements of the adsorption properties of polymers and proteins on smooth titanium oxide surfaces that mimic implant products in orthopedics. The adsorption of BMP-2 on a bare titanium oxide surface is compared to that on titanium oxide coated with different chemically modified hyaluronan, the most important being hyaluronan with bisphosphonate groups (HA-BP). The subsequent release of the BMP-2 from these hydrogel coatings could be triggered by calcium ions. The amount of adsorbed protein on the surfaces as well as the amount of released protein both depend on the type of hyaluronan coating. We conclude that HA-BP coated titanium oxide surfaces provide an excellent material for growth factor delivery in-vivo

Dynamics of viscous amphiphilic films supported by elastic solid substrates

The dynamics of amphiphilic films deposited on a solid surface is analyzed for the case when shear oscillations of the solid surface are excited. The two cases of surface- and bulk shear waves are studied with film exposed to gas or to a liquid. By solving the corresponding dispersion equation and the wave equation while maintaining the energy balance we are able to connect the surface density and the shear viscocity of a fluid amphiphilic overlayer with experimentally accessible damping coefficients, phase velocity, dissipation factor and resonant frequency shifts of shear waves.Comment: 19 pages, latex, 3 figures in eps-forma