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Objectives: Syncope is a non-traumatic and self-limiting transient loss of consciousness (TLOC) caused by momentary cerebral hypo-perfusion. It can be classified into orthostatic, cardiac, and vasovagal etiologies, distinguished using the up-tilt table test (HUTT). Our objective was to determine the characteristics of patients undergoing HUTT for TLOC. Methodology: We conducted a single-center retrospective chart review of patients aged > 16 years who underwent HUTT from January 2010 to March 2020 at the cardiology and neurology departments of Shifa International Hospital, Islamabad, Pakistan. Charts were reviewed for basic demographic data and indications and outcomes of HUTT. Results: Our study included 496 patients with 72.2% males and a mean age of 51.1 ± 19.08 years. Vasovagal syncope was the most common etiology (79.8%, 158), followed by orthostatic syncope (11.6%, 23), autonomic syncope (6.1%, 12) and postural orthostatic tachycard ia syndrome (2.5%, 5). Vasovagal syncope was divided into three subtypes, with the most common being mixed type (82.3%, 130), followed by pure vasodepressor (14.6%, 23) and cardio-inhibitory (3.2%, 5). The two most common prodromal symptoms were loss of consciousness (45.8%, 227) with or without preceding dizziness, followed by dizziness alone (34.5%, 171). Both symptoms had a statistical significance when compared to the diagnostic yield of HUTT testing (p<0.05). No significant correlation (p>0.05) was found between presenting symptoms, age, gender, and HUTT outcomes. Conclusion: The most common etiology of syncope is vasovagal, predominantly the mixed type. LOC and dizziness were significantly associated with the HUTT yield. [ABSTRACT FROM AUTHOR]

Stamp forming method used for forming of relatively smaller and complex-shaped fiber metal laminate (FML) parts has inherent constraints such as fiber sheet rupture, metallic layers quantity, and repeated heating/solidification of thermoplastic (TP) resin/tooling. As an alternate and efficient strategy, simultaneous forming of multiple blanks has been studied by using hydro-mechanical deep drawing (HDD) method. Also, the effect of process variables such as cavity pressure and blank holding force (BHF) and their role in wrinkles formation, thinning, edges movement and formability for the HDD process (performed with and without applying the cavity pressure) has been deliberated. Blanks made of Al 2024-O alloy sheet were used and the formability attributes, based on Barlat 2000 yield criteria, were estimated using DYNAFORM/LS-DYNA and compared with the experimental results. The results show that application of cavity pressure within certain limits has a positive effect on the quality of three-layer formed part as well as leads to higher depths as compared with the process when no cavity pressure was applied. Good agreement has been found between the predicted and the experimental results. The simultaneous forming strategy can give the advantage of eradicating the strict process controls which are needed in the conventional stamp forming method and can expand the application areas of FML parts for the aerospace and automobile industries. [ABSTRACT FROM AUTHOR]

Shrinkage is a common problem in injection-molded parts. This study finds a way to reduce the linear and volumetric shrinkage by using microcellular foaming process. Experiments were conducted by using unfilled and filled (25% short glass fiber reinforced) acetal copolymer samples to demonstrate the effect. The overall improvement in shrinkage was observed therefore the result of increasing weight reduction in the samples. Therefore weight reduction can be utilized to achieve higher-dimensional tolerances of polymer parts and filled polymer can be used if greater mechanical properties are also a matter of concern. [ABSTRACT FROM AUTHOR]

Pseudo-tetragonal phase boundary existent Ca0.60(Li0.5Bi0.5)0.40Bi2Nb2O9:xwt%MnO2 (CBNL:xMn) ceramic series is fabricated to investigate the ferroelectric and piezoelectric properties. Pure CBNL and CBNL:xMn ceramics have maintained their pseudo-tetragonal phase boundary even after the insertion of Mn ions. The addition of MnO2 in CBNL has improved the multifunctional properties of material at x = 0.20. CBNL:0.20Mn has shown the relative density of 98%, saturated polarisation (PS) of ~ 13.5 µC/cm2, high piezoelectric coefficient (d33) of ~ 25 pC/N, and high impedance of ~ 8.9 × 108 Ω at room temperature, which are the much improved values as compared to pure CBN or CBNL ceramics. The dielectric constant (ɛr) dependence on temperature is presenting the sharp peak of CBNL:0.20Mn ceramic at Curie temperature (TC) ~ 918°C confirming the strong ferroelectric nature of the ceramic. Importantly, poled CBNL:0.20Mn ceramic has shown the thermally stable depoling performance, which remains 92% (23 pC/N) of its initial room temperature value even after annealing the sample at 800°C. Results indicate the clear significance that the introduction of multivalence Mn ions in the pseudo-tetragonal existent region of CBNL has improved the multifunctional properties of the material, making it a strong candidate to be utilised in actuators and high-temperature piezoelectric devices. [ABSTRACT FROM AUTHOR]

Lightweight, hybrid parts are extensively used in the manufacturing of modern aerospace or automobile structures like fiber metal laminates (FMLs) to replace the monolithic metallic parts. Presently, smaller and complex-shaped FML parts are made by applying the stamp-forming techniques. However, due to limited strain of the composite fibers, such techniques are unfit for forming complex profile laminated parts. This study focuses on the use of hydro-mechanical deep drawing (HMDD) for the three layers simultaneous forming of the metallic blanks to fabricate a hemispherical structure which will then be used to make a FML part. Orthogonal test strategy is formulated to investigate the influence of variables such as cavity/pre-bulging pressures, pre-bulging height, and die-binder gap to optimize the forming conditions. FE-based experimental study is done to research the thickness distribution and spring back of the formed multilayer structure. Results show that the research is sufficient in predicting these attributes and can provide a basis to understand the fundamental phenomenon for three-layered, simultaneously formed structures. Hybrid parts fabricated by using multilayer forming can expand the application areas of FMLs. [ABSTRACT FROM AUTHOR]

Morphotropic phased boundary (MPB) existent Bi 0.5 (K 0.2 Na 0.8) 0.5 TiO 3 :xwt%MnO 2 (BKNT:xMn) ceramic system is fabricated to investigate the ferroelectric and piezoelectric properties. All the ceramic samples have maintained the tetragonal (P4mm)-rhombohedral (R3c) structural duality due to MPB regional investigation of BKNT. The addition of MnO 2 in BKNT has improved the multifunctional properties of the material at x ​= ​0.15. BKNT:0.15Mn ceramic has shown the maximum density of 6.98 ​g/cm3, remnant polarization (P r) ​∼ ​32.5 ​μC/cm2, high impedance of ∼108 ​Ω, d 33 of 206 ​pC/N, which are much improved properties than pure single phase BKNT and Bi 0.5 K 0.5 TiO 3 ceramics. The dependence of dielectric constant (ε r) on temperature suggests the relaxor behavior and the high Curie temperature (T C) ​∼ ​410 ​°C for BKNT:0.15Mn ceramic, higher than the T C ​∼ ​360 ​°C of pure BKNT ceramic. The poled ceramics have maintained the stable piezoelectric properties till 300 ​°C. The introduction of multivalence Mn has improved the multifunctional properties of the material significantly, making it a strong candidate to be utilized in actuators and sensors. [Display omitted] • Morphotropic phased boundary (MPB) existent Bi 0.5 (K 0.2 Na 0.8) 0.5 TiO 3 :xwt%MnO 2 (BKNT:xMn) ceramic system is fabricated. • All the ceramic samples have maintained the tetragonal (P4mm)-rhombohedral (R3c) structural duality due to MPB regional investigation of BKNT even after the addition of xwt%MnO 2. • BKNT:0.15Mn ceramic has shown the maximum density of 6.98 ​g/cm3, and remnant Polarization of P r ∼32.5 ​μC/cm2. • BKNT:0.15Mn has shown high impedance of ∼108 ​Ω and d 33 of 206 ​pC/N, which are much improved from the properties of pure Bi 0.5 K 0.5 TiO 3 ceramic. • The relaxor behavior and the high Curie temperature (T C) of ∼410 ​°C has been observed for BKNT:0.15Mn ceramics. [ABSTRACT FROM AUTHOR]