Intact mangrove root electrodes for desalination

Through the benefit of billions of years of evolution, biology has developed tremendous strategies on how to co-exist in high salinity and water scarce environments. Biologically-inspired abiotic systems are becoming a central pillar in how we respond to critical grand challenges that accompany exponential population growth, uncontrolled climate change and the harsh reality that 96.5% of the water on the planet is saltwater. One fascinating biologic adaptation to saltwater is the growth of mangrove trees in brackish swamps and along the coasts. Through a process of salt exclusion, the mangrove maintains a near freshwater flow from roots to leaves to survive. One abiotic approach to water desalination is capacitive deionization, which aims to desalinate low-salinity water sources at energy costs below current technologies, such as reverse osmosis and thermal distillation. In this work, we use one-step carbonization of a plant with developed aerenchyma tissue to enable highly-permeable, freestanding flow-through capacitive deionization electrodes. We show that carbonized aerenchyma from red mangrove roots reduces the resistance to water flow through electrodes by 65-fold relative to carbonized common woody biomass. We then demonstrate the practical use of the intact carbonized red mangrove roots as electrodes in a flow-through capacitive deionization system. These findings have implications in a range of fields including water desalination, bioinspired materials, and plant functionality.

Biological adaptation in mangrove root enables freestanding carbonized architecture to be used as a highly permeable flow-through capacitive deionization electrode.     

A conformal transceive array for 7 T neuroimaging

The first 16-channel transceive surface-coil array that conforms to the human head and operates at 298 MHz (7 T) is described. Individual coil elements were decoupled using circumferential shields around each element that extended orthogonally from the former. This decoupling method allowed elements to be constructed with arbitrary shape, size, and location to create a three-dimensional array. Radiofrequency shimming achieved a transmit-field uniformity of 20% over the whole brain and 14% over a single axial slice. During radiofrequency transmission, coil elements couple tightly to the head and reduce the amount of power necessary to achieve a mean 90° flip angle (660-μs and 480-μs pulse lengths were required for a 1-kW hard pulse when shimming over the whole brain and a single axial slice, respectively). During reception, the close proximity of coil elements to the head increases the signal-to-noise ratio in the periphery of the brain, most notably at the superior aspect of the head. The sensitivity profile of each element is localized beneath the respective shield. When combined with the achieved isolation between elements, this results in the capacity for low geometry factors during both transmit and receive: 1.04/1.06 (mean) and 1.25/1.54 (maximum) for 3-by-3 acceleration in the axial/sagittal plane. High cortical signal-to-noise ratio and parallel imaging performance make the conformal coil ideal for the study of high temporal and/or spatial cortical architecture and function.     

Slice-by-slice B(1) (+) shimming at 7 T

Parallel transmission has been used to reduce the inevitable inhomogeneous radiofrequency fields produced in human high‐field MRI greater than 3 T. Further improvements in the transmit homogeneity and efficiency are possible by leveraging the additional degree of freedom permitted by multislice acquisitions. Compared to simple scaling of the flip angle to compensate for B₁⁺ falloff along the radiofrequency coil, calculation of B₁⁺ shim solutions on a slice‐by‐slice basis can markedly improve homogeneity and/or reduce transmitted power and global SAR. Performance measures were acquired at 7 T with a 15‐channel head‐only transceive array featuring elements distributed over all three logical axes, facilitating B₁⁺ shimming over arbitrary orientations. Compared to a circularly polarized volume mode of the same coil, shimming to maximize excitation efficiency on a slice‐by‐slice basis yielded improvements in mean B₁⁺ by 12.8 ± 2.4% and a reduction in standard deviation of B₁⁺ of 16.3 ± 6.8%, while reducing relative SAR by 6.2 ± 3.1%. When shimming for greater uniformity, the mean and standard deviation of B₁⁺ were further improved by 15.9 ± 2.6% and 26.2 ± 10.4%, respectively, at the expense of a 135 ± 8% increase in global SAR. Robust multislice‐shim solutions are demonstrated that can be quickly calculated, applied in real time, and reliably improve on volume coil modes. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.     

High-resolution spiral CT of the breast at very low dose: concept and feasibility considerations

Objective  

Mammography, today’s standard imaging approach, has deficits with respect to the superimposition of anatomical structures. Dedicated CT of the breast so far indicated that it can provide superior soft-tissue imaging, but that it still has significant limitations with respect to spatial resolution and dose. We have assessed novel dedicated breast CT technology.     

Systematic review: Bias in imaging studies - the effect of manipulating clinical context,recall bias and reporting intensity

Objectives  

To perform a systematic review of diagnostic test accuracy studies which manipulate or investigate the context of interpretation. In particular, those which modify or conceal sample characteristics (e.g. disease prevalence or reporting intensity) or research setting (“laboratory” versus “field”). We also investigated recall bias.     

Complete fifth ray amputation with peroneal tendon transfer-a staged surgical protocol

Nonhealing neuropathic ulcers overlying the fifth metatarsal are frequently associated with cavus foot structure and are often complicated by osteomyelitis. Partial fifth ray amputation for metatarsal phalangeal joint ulceration and osteomyelitis is a time-proven procedure. Recurrent wounds and persistent osteomyelitis at the amputation stump or fifth metatarsal base create significant challenges in a cavus foot with neuropathy. Long-term success with removal of the entire fifth ray is largely dependent on preventing infection of the cuboid and maintaining peroneal tendon function. The described technique demonstrates our surgical principles and technical pearls in performing a staged complete fifth ray amputation with initial antibiotic bead placement and delayed peroneal tendon transfer. The peroneus longus tendon transfer has the advantage of preserving the eversion force to counterbalance the posterior tibial tendon and allowing the first ray to elevate, thereby alleviating some of the sagittal plane deformity associated with a cavus foot structure. The surgical tips and pearls are accompanied by procedure indications and incision planning options. To our knowledge, this is the first report of a staged protocol involving complete fifth ray resection, initial antibiotic bead placement, and delayed peroneus longus tendon transfer.     

Caution Should be Taken in Performing Surgical Hip Dislocation for the Treatment of Femoroacetabular Impingement in Patients Over the Age of 40

Background

Open and arthroscopic procedures are treatment options for patients with femoroacetabular impingement (FAI). Age has been found to be a predictive factor in the outcome of patients undergoing periacetabular osteotomy (PAO) for hip dysplasia. It is unclear if older age contraindicates joint preservation through a surgical hip dislocation (SHD).

Questions/Purpose

The purpose of this retrospective case series was to evaluate the short-term outcomes of patients over 40 years of age without radiographic evidence of end-stage arthritis who underwent SHD for the treatment of FAI and to determine whether older age should be a contraindication for joint-preserving procedures in these patients. Our specific aims included (1) documenting the intraoperative findings and procedures, (2) assessing pain relief provided, and (3) assessing treatment failures and postoperative complications, noting the number of patients that ultimately required total hip arthroplasty (THA).

Patients and Methods

All patients at age 40 and older who had SHD for the treatment of FAI were identified from a series of patients treated with SHD. Clinical notes, radiographs, and operative reports were reviewed to determine clinical results, complications, and the need for additional procedures. The minimum follow-up was 1 year (mean 3.9 years; range 1–8 years).

Results

At final follow-up, 11/22 (50%) of hips had pain relief, while 11/22 (50%) either continued having significant symptoms or required THA. Five (23%) reported nontrochanteric pain symptoms that were the same or worse than before surgery, and six hips (27%) underwent subsequent THA). The average time between SHD and THA was 1.9 years (0.9–6.2). The average age of patients who went on to require THA was 45 (42–50) years.

Conclusions

Surgical hip dislocation can be used for the treatment of FAI in patients over age 40, but strict selection criteria should be adhered to, as only half of the patients experienced significant improvement in their hip pain. THA was required in one-third of hips for continued pain and radiographic progression of arthritis. SHD for treatment of pathology that is not amenable to hip arthroscopy should remain a surgical option in older patients with FAI only if joint degeneration is not present.