Ultrasonic welding of printed/molded sustainable polymer specimens with energy directors.

Fused deposition modeling is preferred to fabricate the biodegradable poly lactic acid (PLA) parts, owing to its impeccable characteristics, such as, customization, waste minimization and scalability. However, limited printing volume constraint restricts the ubiquitous applications of this technique. The current experimental investigation is focused on the employment of ultrasonic welding technique to address the printing volume challenge. The effect of infill density, type of energy directors (triangular (TED), semicircular (SCED) and cross energy directors (CED)) and different levels of welding parameters have been investigated on the mechanical and thermal behavior of welded joints. Presence of rasters and gap between them plays a pivotal role in overall heat generation at weld interface. The joint performance of 3D printed parts has also been compared with injection molded specimens of same material. All printed/molded welded specimens with CED recorded higher tensile strength than equivalent specimens with TED and SCED. Moreover, These specimens also performed better than specimens without energy directors and recorded higher tensile strength, that is, 317, 73.5, 59.7 and 42% higher for injection molded (IM), 80%, 90% and 100% infill density (IF) specimens without energy directors at lower level of welding parameters (LLWP). These specimens also exhibited higher tensile strength at optimal levels of welding parameters. Although, at medium and higher levels of welding parameters, both printed/molded specimens with CED observed comparatively more degradation of joints due to higher concentration of energy at weld interface. The dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG) and field emission scanning electron microscopy (FESEM) analysis have been performed to substantiate the experimental results.

An integrated multi-criteria decision-making framework for the selection of sustainable biodegradable polymer for food packaging applications.

Manifold aspects, such as the booming market for superior quality food items with increased shelf life and the escalating concern to mitigate plastic trash due to plastic packaging have motivated researchers and food industrialists to explore sustainable eco-friendly packaging solutions extensively. Biodegradable polymers are being rigorously investigated to replace conventional plastics that are toxic, non-biodegradable, and detrimental to the marine ecosystem. The scientific methodology for the prudent selection of biodegradable polymer among the frequently used biopolymers for food packaging is being reported here. The data were extracted from the available literature. A hybrid multi-criteria decision-making framework has been developed to address the problem of material selection owing to the multiple conflicting criteria involved. Assignment of equal weights to primary criteria was selected to establish the criteria weights. Different decision-making techniques (weighted sum method (WSM), weighted product method (WPM), weighted aggregated sum product assessment method (WASPAS), and technique for order of preference by similarity to ideal solution (TOPSIS)) were used for the comparative analysis. Thereon, the different ranks obtained for each alternative were aggregated using the degree of membership technique. The robustness of the solution was checked using sensitivity analysis which was conducted by varying weights of importance using the entropy method, the CRITIC method, and the equal weights to secondary criteria. The analysis reported polylactic acid (PLA) as the most reliable polymer for food packaging applications. The sensitivity analysis concluded that the solution was without prejudice, and water vapor permeation rating was the most critical decision criterion in deciding the optimal polymer.

Thermal stability of extracted lignin from novel millet husk crop residue.

Recent alarming tones regarding the environment and energy crises have resulted in an emergent need for the utilization of bio-based materials. The current study aims to experimentally investigate the thermal kinetics and pyrolysis behavior of lignin extracted from novel barnyard millet husk (L-BMH) and finger millet husk (L-FMH) crop residue. The characterization techniques FTIR, SEM, XRD, and EDX were employed. TGA was performed to assess the thermal, pyrolysis, and kinetic behavior using Friedman kinetic model. The average lignin yield was obtained as 16.25 % (L-FMH) and 21.31 % (L-BMH). The average activation energy (Ea) was recorded as 179.91-227.67 kJ mol-1 for L-FMH while 158.50-274.46 kJ mol-1 for L-BMH in the conversion range of 0.2-0.8. The higher heating value (HHV) was found to be 19.80 ± 0.09 MJ kg-1 (L-FMH) and 19.65 ± 0.03 MJ kg-1 (L-BMH). The results create a possibility for the valorization of extracted lignin as a potential bio-based flame retardant in polymer composites.

Characterization of AZ31/HA Biodegradable Metal Matrix Composites Manufactured by Rapid Microwave Sintering.

This study reports the development of magnesium alloy/hydroxyapatite-based biodegradable metal matrix composites (BMMCs) through rapid microwave sintering. Magnesium alloy (AZ31) and hydroxyapatite powder were used in four compositions 0, 10, 15 and 20% by weight. Developed BMMCs were characterized to evaluate physical, microstructural, mechanical and biodegradation characteristics. XRD results show Mg and HA as major phases and MgO as a minor phase. SEM results correlate with the XRD findings by identifying the presence of Mg, HA and MgO. The addition of HA powder particles reduced density and increased the microhardness of BMMCs. The compressive strength and Young's modulus increased with increasing HA up to 15 wt.%. AZ31-15HA exhibited the highest corrosion resistance and lowest relative weight loss in the immersion test for 24 h and weight gain after 72 and 168 h due to the deposition of Mg(OH)2 and Ca(OH)2 layers at the sample surface. XRD analysis of the AZ31-15HA sintered sample after an immersion test was carried out and these results revealed the presence of new phases Mg(OH)2 and Ca(OH)2 that could be the reason for enhancing the corrosion resistance. SEM elemental mapping result also confirmed the formation of Mg(OH)2 and Ca(OH)2 at the sample surface, which acted as protective layers and prevented the sample from further corrosion. It showed that the elements were uniformly distributed over the sample surface. In addition, these microwave-sintered BMMCs showed similar properties to the human cortical bone and help bone growth by depositing apatite layers at the surface of the sample. Furthermore, this apatite layer can enhance osteoblast formation due to the porous structure type, which was observed in the BMMCs. Therefore, it is indicative that developed BMMCs can be an artificial biodegradable composite for orthopedic applications.

Plasma transfusion-transmission of Zika virus in mice and macaques.

BACKGROUND: Zika virus (ZIKV) epidemics with infections in pregnant women are associated with severe neurological disease in newborns. Although an arbovirus, ZIKV is also blood transfusion-transmitted (TT). Greater knowledge of the efficiency of ZIKV TT would aid decisions on testing and pathogen reduction technologies (PRT). STUDY DESIGN AND METHODS: Plasma units from ZIKV RNA-reactive blood donors were used to study infectivity in vitro, in mice, and in macaques. Furthermore, plasma units were subjected to PRT using amotosalen/ultraviolet light A (A/UVA) before transfusion. RESULTS: In vitro infectivity of ZIKV RNA-reactive plasma varied between 100 and 1000 international units (IU) of ZIKV RNA. Immunodeficient mice were more sensitive with as low as 32 IU sufficient to infect 50% of mice. 50-5500 IU of RNA led to TT in macaques using dose escalation of three different RNA-positive, seronegative plasma units. In contrast, RNA-reactive units collected postseroconversion were not infectious in macaques, even at a dose of 9 million IU RNA. After A/UVA PRT, transfusion of plasma containing up to 18 million IU was no longer infectious in vitro and did not result in ZIKV TT in macaques. CONCLUSION: Significant risks of ZIKV TT are likely confined to a relatively short viremic window before seroconversion, and that sensitive nucleic acid amplification testing likely identifies the majority of infectious plasma. PRT was demonstrated to be effective at preventing ZIKV TT. Considering that there is no approved ZIKV vaccine, these data are relevant to mitigate the risk of TT during the future ZIKV outbreaks.

Ga-68 DOTATATE Positron Emission Tomography/Computed Tomography in a Rare Case of Esthesioneuroblastoma.

We describe the Ga-68 DOTATATE positron emission tomography/computed tomography (PET/CT) findings of a 51-year-old man, operated for right esthesioneuroblastoma. Postoperative Ga-68 DOTATATE PET/CT revealed focal uptake anterior to sphenoid ostium on the right paramedian side, suspicious for residual disease. Magnetic resonance imaging showed an enhancing lesion in posterosuperior nasal cavity on the right side extending into the right sphenoid sinus. He underwent re-surgery and adjuvant chemoradiotherapy. The histopathology revealed residual olfactory neuroblastoma. The follow-up Ga-68 DOTATATE PET/CT was negative. This case emphasizes the role of Ga-68 DOTATATE PET/CT in the management, especially in residual or recurrent disease and potential radiotheranostics for these rare tumors.

Remnant-Preserving Anterior Cruciate Ligament Reconstruction: Remnant Envelope Technique.

The awareness of anterior cruciate ligament (ACL) injuries and their treatment is increasing among athletes and within the general population, so patients report early to orthopaedic surgeons. Because we encounter a thick ACL stump during arthroscopic ACL reconstruction, an attempt is made to preserve this stump. Remnant preservation-although promising in terms of graft healing because it enhances cell proliferation, revascularization, and regeneration of the proprioceptive organs in the reconstructed ACL-does not come without complications, such as cyclops lesions, impingement, and extension loss. These problems can be detrimental to an athlete's return to his or her preinjury level after ACL reconstruction. Therefore, we describe a technique in which the ACL is reconstructed using hamstring autograft and suture passes are made through the remnant with an antegrade suture-passing device. After anatomic tunnel drilling, the remnant is tensioned, along with the reconstructed ACL, at the femoral end without the use of an extra implant. Femoral-side fixation is achieved with an adjustable-loop button (Procinch; Stryker) and a bio-composite interference screw (Biosure Regenesorb; Smith & Nephew) on the tibial end. As the sutured remnant is tensioned and knots are made over the button, the remnant envelopes the graft in the orientation of the native ACL, which can be helpful for early and better ligamentization of the graft. The potential advantages of this technique are as follows: orientation of the remnant along the collagen of the ACL graft; no loose ACL stump in the notch, thus preventing cyclops lesions; retention of the proprioceptive organs in the ligament; and no extra implant.

Post Stapedotomy Vestibular Deficit: Is CO2 Laser Better than Conventional Technique? A Non-randomized Controlled Trial.

The current standard of care for surgical management of Otosclerosis is small fenestra stapedotomy, which can be done by CO2 Laser assisted as well as conventional techniques. Vertigo is the commonest complication after stapes surgery. The use of CO2 Laser has been rising recently owing to its no touch principle, high precision and possibly lower risk of vertigo post operatively. To compare the post-operative vestibular deficit in patients of Otosclerosis having undergone small fenestra stapedotomy by conventional versus CO2 Laser assisted technique. 80 clinically diagnosed Otosclerosis patients fulfilling the inclusion criteria were enrolled. They underwent small fenestra stapedotomy by either conventional or CO2 Laser assisted technique. Vestibular function was assessed objectively by measuring sway velocity using modified clinical test of sensory interaction on balance by static posturography. Subjective measurement of balance was done using Vestibular balance subscore of Vertigo Symptom Score (VSS-sf-V). The outcome measures were compared pre-operatively and at first and fourth week post-operatively. All patients had vestibular deficit 1 week post-operatively in the form of increased sway velocity and symptom scores, which reduced by 4 weeks after Stapedotomy. The vestibular deficit in the two groups was similar at 1 week after surgery. 4 weeks after surgery, the sway velocity in conventional group was significantly greater than Laser group though there was no significant difference in the symptom scores. The use of CO2 Laser for Stapedotomy results in lesser post-operative vestibular deficit as compared to conventional method.