Knowing the elastic modulus of human dental enamel is of high importance since dental filling materials should posses equal mechanical properties as enamel itself. If this demand is not fulfilled, the interaction between filling and enamel is not equivalent, so that healthy enamel could be simply abrased during chewing. Hence it is astonishing that the literature shows a big variety of suggestions for the elastic modulus. This paper will give a short overview about some existing results (maybe not all) and tries to compare and evaluate them. The experiments have been done too, trying to make it more easy for the experienced reader to make up his own mind about the elastic modulus of human dental enamel.
Finding an ideal biomaterial with the proper mechanical properties and biocompatibility has been of intense focus in the field of soft tissue engineering. This paper reports on the synthesis and characterization of a novel crosslinked urethane-doped polyester elastomer (CUPOMC), which was synthesized by reacting a previously developed photocrosslinkable poly (octamethylene maleate citrate) (POMC) prepolymers (pre-POMC) with 1,6-hexamethylene diisocyanate (HDI) followed by thermo- or photo-crosslinking polymerization. The mechanical properties of the CUPOMCs can be tuned by controlling the molar ratios of pre-POMC monomers, and the ratio between the prepolymer and HDI. CUPOMCs can be crosslinked into a 3D network through polycondensation or free radical polymerization reactions. The tensile strength and elongation at break of CUPOMC synthesized under the known conditions range from 0.73±0.12MPa to 10.91±0.64MPa and from 72.91±9.09% to 300.41±21.99% respectively. Preliminary biocompatibility tests demonstrated that CUPOMCs support cell adhesion and proliferation. Unlike the pre-polymers of other crosslinked elastomers, CUPOMC pre-polymers possess great processability demonstrated by scaffold fabrication via a thermally induced phase separation method. The dual crosslinking methods for CUPOMC pre-polymers should enhance the versatile processability of the CUPOMC used in various conditions. Development of CUPOMC should expand the choices of available biodegradable elastomers for various biomedical applications such as soft tissue engineering.
Intrabody communication (IBC) is one of the recent physical layers of the IEEE 802.15.6 Wireless Body Area Networks (WBAN) communication standard. It is employed for data transmission in low frequency bands (21 MHz as per standard, 0.3-120 MHz in literature), providing up to 10 Mbps data throughput. An effective way to increase data rate communication is to determine higher operation frequency bands. This paper reports empirical studies which explore signal propagation through the human body including limb joints within the 0.3-200 MHz frequency range. Results show that minimum signal attenuation points occur at 50 MHz and 150 MHz within the range of investigation. The presence of the joint segments along the signal propagation path causes on average 2.0 dB loss (at 50 MHz and 150 MHz), 6.0 dB loss (<1 MHz) and less than 3.0 dB (>150 MHz) compared to limb segments.
The market of tools, devices, and processes for medical treatments and diagnosis has been growing at a very fast pace, driven by the multi-disciplinary development of integrated innovative technologies. In this article, the way artificial organs design is currently taught is analyzed and discussed relative to the evolution of the methods of artificial organs design as substitution of physical and metabolic bodily functions. Particular attention is devoted to the evolution from empirical attempts at providing generic replacement of a single mechanical function to a more systematic multi-purpose approach that increasingly accounts for biological issues. As a result, at the forefront of research, the paradigm is shifting from mechanical/electronic prostheses towards the development in vitro of tissue engineered organs/tissues, where the artificial part is fully integrated with the biological counterpart. Personalized solutions for each patient rather than a generic solution good for all patients are also sought.
Visual orienting is critical signal to ability of attention. In particular, eye gaze is one of important visual orienting to refer our belief, desires and feeling etc. However, in real life, visual orienting has been indicated to be influenced by others modality processing, such as auditory supplement. Less previous studies have been comprehensively investigated how visual orienting is influenced by auditory processing. In this study, the authors conduct two experiments to investigate how visual orienting effect would be influenced by auditory processing, when used nonsocial and social stimuli as cues respectively (i.e., arrow and eye gaze). The results indicate that visual orienting is clearly influenced by auditory processing in both social and non-social stimuli as cues. Functional MRI data suggest that DLPFC plays an important role in regulating visual and auditory attention.
Heart valve replacement is fast becoming a routine surgery worldwide, and heart valve prostheses are today considered among the most widely used cardiovascular devices. Mechanical and bioprostheses have been the traditional choices to the replacement surgeries. However, such valves continue to expose patients to risks including thrombosis, infection and limited valve durability. In recent years, advances in polymer science give rise to an important new class of artificial heart valve made predominantly of polyurethane-based materials, which show improved biocompatibility and biostability. These polymeric heart valves have demonstrated excellent hemodynamic performance and good durability with excellent fatigue stress resistance. Advancements in the designs and manufacturing methods also suggested improved in the durability of polymeric heart valves. Animal studies with these valves have also shown good biocompatibility with minimal calcification of the valve leaflets. With these promising progresses, polymeric heart valves could be a viable alternative in the heart valve replacement surgeries in the near future.
Gelatin films from cold water fish skin filled with designed antimicrobial peptide or silver nanoparticles were formulated for biomedical applications. Antibacterial activities of gelatin films containing silver nanoparticles and lytic peptides were evaluated to study the growth of a Staphylococcus species. The results suggest that inclusion of silver nanoparticles and lytic peptides into the composition of biocompatible films is feasible, with significant retention of the antimicrobial activity for both agents. The results presented here give evidence that both the silver nanoparticles and lytic peptides retain their antibacterial activity in such film matrices and the surrounding medium. Therefore, such biocompatible films may have potential use in biomedical applications such as wound dressing, superficial infection and contamination control. Evaluation of the mechanical properties for silver nanoparticles gelatin films revealed that the tensile strength appeared to be optimal at 0.3% silver nanoparticles loading. However, the strain-to-failure decreased with respect to the neat film.
The proposed device is a rehabilitation aid for the prevention of secondary diseases usually associated with Spinal Cord Injury. In such patients the calf muscles are degenerated and there is abnormality in systemic blood circulation. Thus there is a high risk of the patient being subjected to death. For faster recovery in such a patient, it is medically recommended that he or she is given continuous passive motion for a longer duration. This is done by a physiotherapist using his manual power. The movements usually given are: adduction and abduction, flexion and extension, plantar-flexion and dorsi-flexion. The outcome of such a process will be very limited as it is a laborious task. Thus the main objective behind this project is to provide continuous movement so as to improve the patient’s joint mobility and muscle flexibility thereby enhancing the blood circulation and neuro muscular activity in a low-cost technique. The device automatizes all the movements provided by a physiotherapist. Three different motors are used to control each of the movements listed. Basically, it is a mechanical model in which speed, torque, angle and time of each of the movements can be adjusted. The device is battery-powered and provides complete patient-circuit isolation and is inclusive of all patient safety parameters.
