Multichannel communication based on adaptive equalization in very shallow water acoustic channels

Master'sMASTER OF ENGINEERIN

Use of the cross-leg distally based sural artery flap for the reconstruction of complex lower extremity defects

Cross-leg flaps are a useful reconstructive option for complex lower limb defects when free flaps cannot be performed owing to vessel damage. We describe the use of the extended distally based sural artery flap in a cross-leg fashion for lower extremity coverage in three patients. To maximise the viability of these extended flaps, a delay was performed by raising them in a bipedicled fashion before gradual division of the tip over 5 to 7 days for cross-leg transfer. Rigid coupling of the lower limbs with external fixators was critical in preventing flap avulsion and to promote neovascular takeover. The pedicle was gradually divided over the ensuing 7 to 14 days before full flap inset and removal of the external fixators. In all three patients, the flaps survived with no complications and successful coverage of the critical defect was achieved. One patient developed a grade 2 pressure injury on his heel that resolved with conservative dressings. The donor sites and external fixator pin wounds healed well, with no functional morbidity. The cross-leg extended distally based sural artery flap is a reliable reconstructive option in challenging scenarios. Adequate flap delay, manoeuvres to reduce congestion, and postoperative rigid immobilization are key to a successful outcome

Imaging in the Lion City: Singapore Radiology Country Report

Singapore is a small tropical island city-state with limited natural resources that has achieved remarkable healthcare outcomes through effective long-term planning and judicious investment in human resources and technology. A full-range of medical imaging services is available in the country, with integrated care delivered to patients through a network of both government and private hospitals. Training in diagnostic radiology, interventional radiology, nuclear medicine and diagnostic radiography continue to evolve in Singapore, with an aim to further increase the range of subspecialty medical imaging services available and address projected challenges for the healthcare system in the future, such as an aging population. Continued government investment in technology and biomedical imaging is expected to further expand the scope and depth of medical imaging services in the future

Highly water-soluble magnetic iron oxide (Fe3O4) nanoparticles for drug delivery: enhanced in vitro therapeutic efficacy of doxorubicin and MION conjugates

We report a simple one step protocol for the preparation of fairly monodisperse and highly water-soluble magnetic iron oxide nanoparticles (MIONs) through a co-precipitation method using a novel multifunctional, biocompatible and water-soluble polymer ligand dodecanethiol-polymethacrylic acid (DDT-PMAA). DDT-PMAA owing to its several intrinsic properties, not only efficiently controls the size of the MIONs but also gives them excellent water solubility, long time stability against aggregation and oxidation, biocompatibility and multifunctional surface rich in thioether and carboxylic acid groups. The molecular weight and concentration of the polymer ligand were optimized to produce ultrasmall (4.6 +/- 0.7 nm) MIONs with high magnetization (50 emu g(-1)). The MIONs obtained with 1.5 mM DDT-PMAA (5330 g mol(-1)) are highly stable in solution as well as in dry powder form for an extended period of time. These MIONs show a high degree of monodispersity and are superparamagnetic at room temperature. The polymer ligand and MIONs@Polymer were characterized by GPC, H-1 NMR, DLS, TEM, FTIR-Raman, XRD, TGA and VSM. In order to demonstrate the bio-applications of these magnetic nanoparticles (NPs), their toxicity was determined by MTT assay and they were found to be non-toxic and biocompatible. Finally, MIONs were conjugated with the anti-cancer drug doxorubicin (DOX) and its efficacy, as a model drug delivery system, was determined using HepG2 cells. The efficiency of the drug-NP conjugates i.e., covalently bound DOX-MIONs and electrostatically loaded DOX/MIONs, was found to be significantly higher than that of the free drug (DOX)

The State of Interventional Radiology in Myanmar: A National Report

Purpose: Radiology global outreach programs have increased in recent years but progressed more slowly than other specialties. Establishing radiology services is increasingly recognized as a priority in resource-limited settings. Myanmar has a tremendous disease burden that is treatable with interventional radiology (IR) techniques, and aims to grow and effectively integrate this service into its public healthcare sector. Through collaborations between Asia Pacific Society of Cardiovascular and Interventional Radiology (APSCVIR) and Myanmar Radiological Society (MRS), the field of IR has grown exponentially over recent years. This study aims to provide a Myanmar national IR report on the current trends and future challenges. Methods and materials: Descriptive variables across five domains (facility and equipment, workforce, supplies, infrastructure, and casemix) from the four public sector hospitals with IR capability were obtained between 2016-2019. The four hospitals were Yangon General Hospital (YGH), Yangon Specialty Hospital (YSH), Mandalay General Hospital (MGH), and Defense Services General Hospital (DSGH). Data were analyzed to demonstrate progress in IR and the differing casemix. Results: There are currently four IR-capable hospitals and nine interventional radiologists across Myanmar’s public healthcare sector. IR case volumes tripled from 514 cases in 2016 to more than 1,500 cases in 2019. The three most common procedures performed were trans-arterial chemoembolization (TACE, 63%), bronchial arterial embolization (BAE, 7.7%), and drainages (7.7%). Significant challenges to the growth and adoption of IR services span the domains of infrastructure, equipment and supplies, workforce, and IR awareness, among other clinical specialties. Conclusion: Myanmar’s healthcare priorities, coupled with international radiological outreach programs, have led to rapid growth of IR. The exponential growth in case volumes is promising for Myanmar and other developing countries. But to widen the scope of practice and integrate the service within local clinical workflows, a holistic effort that addresses multiple domains is needed in the future

Layered microporous polymers by solvent knitting method

Two-dimensional (2D) nanomaterials, especially 2D organic nanomaterials with unprecedentedly diverse and controlled structure, have attracted decent scientific interest. Among the preparation strategies, the top-down approach is one of the considered low-cost and scalable strategies to obtain 2D organic nanomaterials. However, some factors of their layered counterparts limited the development and potential applications of 2D organic nanomaterials, such as type, stability, and strict synthetic conditions of layered counterparts. We report a class of layered solvent knitting hyper-cross-linked microporous polymers (SHCPs) prepared by improving Friedel-Crafts reaction and using dichloroalkane as an economical solvent, stable electrophilic reagent, and external cross-linker at low temperature, which could be used as layered counterparts to obtain previously unknown 2D SHCP nanosheets by method of ultrasonic-assisted solvent exfoliation. This efficient and low-cost strategy can produce previously unreported microporous organic polymers with layered structure and high surface area and gas storage capacity. The pore structure and surface area of these polymers can be controlled by tuning the chain length of the solvent, the molar ratio of AlCl(3), and the size of monomers. Furthermore, we successfully obtain an unprecedentedly high–surface area HCP material (3002 m(2) g(−1)), which shows decent gas storage capacity (4.82 mmol g(−1) at 273 K and 1.00 bar for CO(2); 12.40 mmol g(−1) at 77.3 K and 1.13 bar for H(2)). This finding provides an opportunity for breaking the constraint of former knitting methods and opening up avenues for the design and synthesis of previously unknown layered HCP materials

Gracilis pull-through flap for the repair of a recalcitrant recto-vaginal fistula

Recto-vaginal fistulas are difficult to treat due to their high recurrence rate. Currently, no single surgical intervention is universally regarded as the best treatment option for rectovaginal fistulas. We present a case of recurrent recto-vaginal fistula surgically treated with a gracilis pull-through flap. The surgical goals in this patient were complete excision of the recto-vaginal fistula and introduction of fresh, vascularized muscle to seal the fistula. A defunctioning colostomy was performed 1 month prior to the present procedure. The gracilis muscle and tendon were mobilized, pulled through the freshened recto-vaginal fistula, passed through the anus, and anchored externally. Excess muscle and tendon were trimmed 1 week after the procedure. Follow-up at 4 weeks demonstrated complete mucosal coverage over an intact gracilis muscle, and no leakage. At 8 weeks post-procedure, the patient resumed sexual intercourse with no dyspareunia. At 6 months post-procedure, her stoma was closed. The patient reported transient fecal staining of her vagina after stoma reversal, which resolved with conservative treatment. The fistula had not recurred at 20 months post-procedure. The gracilis pull-through flap is a reliable technique for a scarred vagina with an attenuated rectovaginal septum. It can function as a well-vascularized tissue plug to promote healing

RSNA International Trends: A Global Perspective on the COVID-19 Pandemic and Radiology in Late 2020

The COVID-19 pandemic has challenged and changed our healthcare systems around the world. There has been a heterogeneity of disease burden, healthcare resources, and non-imaging testing availability, both geographically and over time. In parallel, there has been a continued increase in understanding of how the disease affects patients, effectiveness of therapeutic options, and factors that modulate transmission risk. Here we detail experiences from radiology experts in representative countries from around the world, to share insights gained from local experience. These insights provide a guidepost to help address management challenges as cases continue to rise in many parts of the world and suggest modifications in workflow that are likely to continue after this pandemic subsides