Magnetic-field-induced stress in confined magnetoactive elastomers.

We present a theoretical approach for calculating the state of stress induced by a uniform magnetic field in confined magnetoactive elastomers of arbitrary shape. The theory explicitly includes the magnetic field generated by magnetizable spherical inclusions in the sample interior assuming a non-linear magnetization behavior. The initial spatial distribution of particles and its change in an external magnetic field are considered. This is achieved by the introduction of an effective demagnetizing factor where both the sample shape and the material microstructure are taken into account. Theoretical predictions are fitted to the stress data measured using a specifically designed experimental setup. It is shown that the theory enables the quantification of the effect of material microstructure upon introducing a specific microstructural factor and its derivative with respect to the extensional strain in the undeformed state. The experimentally observed differences between isotropic and anisotropic samples, compliant and stiff elastomer matrices are explained.

[Robot-assisted and robotic systems used in dentistry]. / Robot-assistirovannye i robotizirovannye sistemy, primeniaemye v stomatologii.

In the present study, the role of robot-assistance in dentistry and the main ways of its further development are analyzed. The basic structures of mechatronic devices and the features of their application in dentistry were reviewed. A retro-prospective analysis of the structures of robotic and robot-assisted systems used in dental practice was carried out. The development of robot-assisted and robotic systems should include the improvement of methods of intraoperative imaging, diagnostic tools, the improvement of surgical instruments, as well as the emergence of new robotic developments.

[Cephalometric study of 9-15 years old patients with maxillofacial anomalies and cerebral palsy]. / Tsefalometricheskie parametry u patsientov v vozraste 9-15 let s zubocheliustnymi anomaliiami i detskim tserebral'nym paralichom.

AIM: To study the morphological state of the maxillofacial system in children with cerebral palsy. MATERIAL AND METHODS: The frequency and prevalence of dental anomalies was studied in 30 9-15 years old children with cerebral palsy. For the registration of maxillofacial anomalies, the Bjork assessment method was used. The severity of sagittal incisive disocclusion and the reverse sagittal incisal disocclusion was measured by the magnitude of the sagittal slit. RESULTS: The study revealed no age-dependent correlation of lower canines and second premolars roots growth. The parameters of the cerebral part of the skull measured on the CT-bases lateral cephalograms were significantly less than normal rates except for the length of the posterior part of the skull. CONCLUSION: The morphological changes that determined the formation of sagittal and vertical incisive disocclusions were defined: the reduction of total anterior morphological face height (N-Me) and anterior upper morphological face height (N-SpP) and the increase in the anterior lower morphological face height (SpP-Me) which are characteristic features for patients with incisive sagittal and vertical diocclusion.

[Technology of manufacturing of personalized reconstructive allogenic bone graft (in Russian only)]. / Tekhnologiia proizvodstva personifitsirovannogo rekonstruktivnogo allogennogo kostnogo implantata.

AIM: To develop the technology of manufacturing of reconstructive allogenic bone graft with individual parameters by using of digital prototyping and modeling. MATERIAL AND METHODS: Allogeneic cadaveric bone blocks were used as material. The following methods were used to develop a manufacturing technology for personalized allogenic reconstructive bone implant: harvesting and special preparation of cadaveric material, primary disinfection, viral inactivation, ultrasound management, lyophilization of bone material, CT-examination of patients with various bone defects, digital prototyping and modeling, milling on a machine with numerical program control, X-ray sterilization. RESULTS: The technology of manufacturing of reconstructive allogenic bone graft with individual parameters was successfully tested in the treatment of 24 patients with post-traumatic, destructive-dystrophic and degenerative defects of jaws in 2012-2015. Final reconstructive allogenic bone implant has a personalized 3D-geometry in accordance with individual maxillofacial anatomy of particular patient. One of implant surfaces is fully congruent to the jaw bone defect, the others form the width, height and volume of reconstructive bone implant considering personified maxillofacial features. All above-mentioned features of bone implant are important to restore chewing function of dental system. CONCLUSION: The problem of bone implant personification may be resolved by using of computed tomography followed by digital analysis of jaw structure, technologies for digital reconstruction of bone defects (digital prototyping and modeling) and digital manufacturing.

Hysteresis of the magnetic properties of soft magnetic gels.

We present results of an experimental and theoretical study of the magnetic properties of soft magnetic gels consisting of micron-sized magnetizable particles embedded in a polymer matrix. Experiments demonstrate hysteretic dependences of composite magnetization on an applied magnetic field and non-monotonic, with maximum, dependence of the sample susceptibilities on the field. We propose a theoretical approach which describes the main physical features of these experimental results.

[Comprehensive treatment of malocclusion class III in teeth-alveolar contraction].

In this study complex treatment of a patient aged 12 years and 4 months with malocclusion class III accompanied by teeth-alveolar contraction was carried out. Preadjusted appliance system for widening and lengthening of upper denture was used. Teeth 34, 44 were extracted. Denture closing was optimized with bracket system. Positive result was achieved in 19 months.

[The study of DNA integrity in somatic cells and spermatozoa by single cell gel electrophoresis with silver staining].

In present work we studied DNA damage in human and bovine lymphocytes and spermatozoa by means of single cell gel electrophoresis followed by silver staining. The spontaneous frequency of DNA damage estimated manually in spermatozoa from healthy donors did not exceed 9% (on average -- 4.8 +/- 1.2%). The frequency of DNA damages in bull sperm after short (less than a year) and long period (more than 20 years) of cryopreservation was assessed as 3.1 +/- 0.9 and 4.3 +/- 0.5%, correspondingly. The comparative estimation of DNA damages in lymphocytes followed by silver staining is a valuable tool to estimate DNA damage in populations of somatic and reproductive cells.

Motion of ferroparticles inside the polymeric matrix in magnetoactive elastomers.

Ferroelastic composites are smart materials with unique properties including large magnetodeformational effects, strong field enhancement of the elastic modulus and magnetic shape memory. On the basis of mechanical tests, direct microscopy observations and magnetic measurements we conclude that all these effects are caused by reversible motion of the magnetic particles inside the polymeric matrix in response to an applied field. The basic points of a model accounting for particle structuring in a magnetoactive elastomer under an external field are presented.