Triply Periodic Minimal Surface (TPMS) is distinctive structure that supports numerous cellular activities and encapsulating trabecular bonemimicking hyperboloidal topography. They have emerged as a prospective choice in reconstructive orthopedic surgery. The hybrid design of these structures is an effective approach to constructing functional implant structures. In this study, we have used TPMS structures to develop the hybrid models with given transition boundaries to investigate the multi-morphology cellular material model for its effectiveness as scaffold use. Sigmoid function was employed to connect more than two TPMS structures, with a special shape at the transition boundary region. Furthermore, numerical simulation was performed to investigate the mechanical performance on hybrid model of IWP (I-graph-wrapped package curved surface) and Diamond (D) (both are the family of TPMS unit cell libraries) with accurately controlled porosity of 50%, 60%, 70% and 80%. The numerical results showed that the proposed hybrid scaffold architecture has the potential to be advantageous for accurately controlling the spatial porosity distribution to tailor the specific bone attributes while maintaining the benefit of the TPMS-based hybrid unit cell libraries.

Porous structure offers the advantage of minimizing stress shielding phenomena and supports bone ingrowth, thereby improving the long-term durability of scaffolds. Unlike conventional techniques, additive manufacturing is capable of fabricating complex pore architecture in an exceedingly controlled fashion. In this paper, implicit surface modeling technique is used to develop the triply periodic minimal surfaces-based scaffolds of varying architectures. Sheet and solid-based wrapped package graph (IWP) and diamond are investigated by finite element analysis of lattices under compression. Parameters of mathematical trigonometric functions are varied to tune the structural characteristics like pore size, porosity on the elastic moduli, and strength of the scaffold. Results indicate that morphological features could be effectively controlled to achieve the desired bone mimicking architectures. In terms of biomechanical performances, IWP and diamond structures achieved the responses similar to surrounding bone tissue and have the good agreement with the data available in the literature for the range of elastic modulus of bone for various anatomical locations; the numerical results show that the architecture, pore size, and porosity have a major impact on performances of scaffolds. Also, in the biomechanical and clinical context, this work highlights the limitations and capabilities of additively manufactured porous scaffolds, thus proposing a permissible design space for the scaffold fabricated by additive manufacturing.

The fluidic behavior of porous scaffolds plays a vital role in the mass transportation of cells and the formation of new tissue, which is crucial for promoting bone ingrowth. TPMS porous structures are widely recognized in the field of tissue engineering as a versatile solution for designing biomorphic scaffolds due to their unique structural and biological properties. To explore the flow behavior of TPMS-based porous scaffolds, we employed a computational fluid dynamics (CFD) approach. Our study focused on two types of TPMS structures: I-graph wrapped package (IWP) and diamond (D); both were developed by using mathematically defined TPMS equations. For each structure, we created four model variants with porosities of 50%, 60%, 70%, and 80%, respectively. These models underwent systematic fluid flow simulations to evaluate important parameters such as permeability, wall shear stress (WSS), pressure distribution, velocity distribution, and pressure drop. These aspects are critical for assessing the suitability of scaffolds as bone substitutes. Our simulation results revealed that the IWP structure exhibited superior fluid accessibility compared to the diamond structure in terms of permeability and WSS. Overall, this investigation emphasizes the benefits of utilizing TPMS structures as a viable option for bone applications. The significant finding of this work underscores the importance of optimizing scaffold architecture to enhance cell ingrowth and transport phenomena at targeted anatomical sites.

Purpose: The current study intended to provide a comparison of biomechanical behaviors of two different treatment concepts for full-mouth rehabilitation with dental implants placed according to the “All-on-four” concept and “All-on-six” concept with analysis of the stress patterns of the implant support system using three-dimensional finite element analysis (FEA). Materials and Methods: The edentulous mandible was treated with two different implant designs. “All-on-Four” implant placement concept was used in Model 1 with two central axial implants and two distally tilted implants at 17° and in Model 2, “All-on-Six” concept was applied with six vertically placed implants. Individual vertical and horizontal load of 100 N and oblique load of 141 N at 45° was applied to all implants. To evaluate and compare the results in terms of maximum principal stress, we used FEA. Results: All-on-six showed smaller maximum principal stress values on the cortical bone and implants. However, maximum principal stress values obtained on trabecular bone was smaller in the All-on-four design for vertical and horizontal loading conditions. Conclusions: The All-on-six approach showed more favorable biomechanical behavior.

A mismatch between the implant and interacting bone Young's modulus causes stress shielding phenomena, which leads to instability of the implant and early failure. This paper focuses on the development of medical-grade titanium alloy (Ti6Al4V)-based metallic highly porous structure to mitigate the stress shielding effect. In this study, we propose an effective method to generate a highly porous implant based on triply periodic minimal surfaces (TPMS) architecture. Three-dimensional models of different TPMS architectures such as Diamond, Gyroid, I-graph-Wrapped Package graph (IWP), and Primitive were constructed with a 2 × 2 × 2 mm lattice size and unit cell size of 1 mm. Mechanical testing of the finite-element models was performed under static loading conditions to evaluate the effective elastic modulus ( E eff ) of each porous architecture. It was found that the primitive structure exhibits the lowest E eff , whereas the Gyroid exhibits the highest E eff , results indicate that porous architecture reduces E eff by more than 95%, thereby reducing the stress shielding effect. Moreover, pore size and surface-area-to-volume ratio (SA/V ratio) were also investigated. Findings suggested that the primitive structure has the highest pore size, which will be suitable for enhanced bone ingrowth. A high SA/V ratio in IWP offers the possibility of enhanced cell adhesion, migration, and proliferation.

Gyroid (G) and primitive (P) porous structures have multiple application areas, ranging from thermal to mechanical, and fall in the complex triply periodic minimal surface (TPMS) category. Such intricate bioinspired constructs are gaining attention because they meet both biological and mechanical requirements for osseous reconstruction. The study aimed to develop G and P structures with varying porosity levels from 40% to 80% by modulating the strut thickness to proportionally resemble the stiffness of host tissue. The performance characteristics were evaluated using Ti6Al4V and important relationships between feature dimension, strut thickness, porosity, and stiffness were established. Numerical results showed that the studied porous structures could decrease stiffness from 107 GPa (stiffness of Ti6Al4V) to the range between 4.21 GPa to 29.63 GPa of varying porosities, which matches the human bone stiffness range. Furthermore, using this foundation, a subject-specific scaffold (made of P unit cells with an 80% porosity) was developed to reconstruct segmental bone defect (SBD) of the human femur, demonstrating a significant decrease in the stress shielding effect. Stress transfer on the bone surrounded by a P scaffold was compared with a solid implant which showed a net increase of stress transfer of 76% with the use of P scaffold. In the conclusion, future concerns and recommendations are suggested.

The structure of the ECG signal is time varying which is the supreme common source used for the purpose of diagnosis & observation and analysis of various types of diseases related to the heart in the patient. ECG recording is the process done by placing the electrodes in the specified positions at body of humans. During the process of recording, a noise distracted signal is applied to ECG signal and the ECG signal is also full of artifacts which always degrades the quality of it and establishes threats in the recording the absolute ECG signal. The artifacts mostly noticed are Power line Interference, Baseline Wander and muscle tremors. Therefore, for accuracy in the characteristics points of ECG, an ECG having good quality is essential. Generally, we notice that these kinds of noises are very common in the process and detection is needed. We found that FIR-IIR filter is giving suitability to increase the quality of it. So, here we are presenting an implementation of the FIR-IIR filter for reduction of artifacts using Xilinx EDA tool and the Power analysis is being done in X-Power analyzer by creating VHDL code and running it into Model Sim 3.1.

Volume 2, Issue 1 January February 2013 Page 161 Abstract: Ultrasound Sonography is believed to be very potential for imaging soft tissues in organs like liver, kidney, spleen, uterus, heart, brain etc. in a minimally invasive way. The main drawback of the ultrasound image is its poor quality, as they are contaminated by a stochastic process known as speckle. Speckle noise is a form of multiplicative noise that inherently exists in all types of coherent imaging systems. While using speckle reduction techniques as an aid for visual diagnosis, it has to keep in mind that certain speckle contains diagnostic information and should be retained. Therefore it is necessary to improve contrast and suppress such noises while retaining as much as possible the important image features for disease identification correctly. The objective of this work is to introduce various filtering techniques for liver ultrasound images including Shock Filter, Gaussian lowpass filter, Butterworth lowpass filter, Median filter and Weiner filter. Peak Signal to Noise Ratio (PSNR) and Mean Square Error (MSE) are used as quality parameters. These two parameters were calculated based on the initial and filtered images. The comparative study concludes that the Gaussian lowpass filtering algorithm gives the better result preserving the finer details in comparison to other methods.