Comparison of insertion time, pull-out strength, and screw-media interface area of customized pedicle screw with different core and thread design against commercial pedicle screw: a pilot study on Indonesian Population

Objective This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22.94 s) with commercially available pedicle screw (15.86 s) (p < 0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p < 0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

Radial dynamics of an encapsulated microbubble with interface energy

In this work a mathematical model based on interface energy is proposed within the framework of surface continuum mechanics to study the dynamics of encapsulated bubbles. The interface model naturally induces a residual stress field into the bulk of the bubble, with possible expansion or shrinkage from a stress-free configuration to a natural equilibrium configuration. The significant influence of interface area strain and the coupled effect of stretch and curvature is observed in the numerical simulations based on constrained optimization. Due to the bending rigidity related to additional terms, the dynamic interface tension can become negative, but not due to the interface area strain. The coupled effect of interface strain and curvature term observed is new and plays a dominant role in the dominant compression behaviour of encapsulated bubbles observed in the experiments. The present model is validated by fitting the experimental data of $1.7\,\mathrm {\mu }$ m, $1.4\,\mathrm {\mu }$ m and $1\,\mathrm {\mu }$ m radii bubbles by calculating the optimized parameters. This work also highlights the role of interface parameters and natural configuration gas pressure in estimating the size-independent viscoelastic material properties of encapsulated bubbles with interesting future developments.

Insights from the Interfaces of Corona Viral Proteins: Homomers Versus Heteromers

The outbreak of COVID-19 and its mutant variants has become a life-threatening and fatal viral disease to mankind. Several studies have been carried out to identify an effective receptor against coronavirus using clinically driven samples distinguished as hematological, immunological and biochemical biomarkers. Simultaneously, protein interfaces are being researched to understand the structural and functional mechanism of action. Therefore, we characterized and examined the interfaces of corona viral proteins using a dataset consisting of 366 homomeric and 199 heteromeric protein interfaces. The interfaces were analyzed using six parameters including interface area, interface size, van der Waal, hydrogen bond, electrostatic and total stabilizing energies. We observed the interfaces of corona viral proteins (homomer and heteromer) to be alike. Therefore, we clustered the interfaces based on the percent contribution of vdW towards total stabilizing energy as vdW energy dominant (≥60%) and vdW energy subdominant (<60%). We found 91% of interfaces to have vdW energy in dominance with large interface size [146±29 (homomer) and 122±29 (heteromer)] and interface area [1690±683 (homomer) and 1306±355 (heteromer)]. However, we also observed 9% of interfaces to have vdW energy in sub-dominance with small interface size [60±12 (homomer) and 41±20 (heteromer)] and interface area [472±174 (homomer) and 310±199 (heteromer)]. We noticed the interface area of large interfaces to be four-fold more when compared to small interfaces in homomer and heteromer. It was interesting to observe that the small interfaces of homomers to be rich in electrostatics (r2=0.50) destitute of hydrogen bond energy (r2=0.04). However, the heteromeric interfaces were equally pronounced with hydrogen bond (r2=0.70) and electrostatic (r2=0.61) energies. Hence, our earlier findings stating that the small protein interfaces are rich in electrostatic energy remaintrue with the homomeric interfaces of corona viral proteins whereas not in heteromeric interfaces.

Mechanical and tribological properties of nano-sized Al2O3 particles on ADC12 alloy composites with Strontium modifier produced by stir casting method

Nano-Al2O3 particles were incorporated into ADC12 alloy with the addition of Al-5Ti-B, Al-Sr, and Mg to achieve high performance in mechanical and tribological properties. In this study, varied nano-Al2O3 was used from 0.25 vf-% to 0.5 vf-% through stir casting methods to discover the optimum amount to obtain high performance. Besides, the inclusion of grain refiner Al-5Ti-B and microstructure modifier Al-Sr is expected to improve performance to the next level. However, porosity and agglomeration still be a concern in Aluminum alloy matrix composite fabrication. The presence of spinel phase MgAl2O4 in the interface area between nano-Al2O3 particles and ADC12 alloy is relied upon to minimize this porosity and agglomeration issue. The optimum of tensile strength and hardness was found at 0.35 vf-% Al2O3 and wear rate at 0.4 vf%. Although, the optimum point of wear found at 0.4 vf%, porosity began to increase at 0.4 vf% as well. As a result, 0.35 vf% addition of the nano-Al2O3 gives the best performance for the composite.

Comparison of Insertion Time, Pull-out Strength, and Screw-media Interface Area of Customized Pedicle Screw With Different Core and Thread Design Against Commercial Pedicle Screw

Objective: This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result: The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22,94 s) with commercially available pedicle screw (15.86 s) (p<0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p<0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

BackgroundGlossina (Tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented and little is known of their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park.MethodsA longitudinal stratified sampling, following the seasons was used. Biconical traps were deployed in 55 sites for six consecutive days of each study month from May 2018 to June 2019, and emptied every 48hours. Flies were identified using FAO keys and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p< 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results39,516 tsetse flies were collected, of which 73.4% and 26.6% were from inside Akagera NP and the interface area respectively. Female flies accounted for 61.3% while 38.7% were males. Two species were identified, i.e. G. pallidipes [n=29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n=10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p=0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times).ConclusionsThe occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band in its surroundings. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended.