Cost Comparison of Femoral Distraction Osteogenesis With External Lengthening Over a Nail Versus Internal Magnetic Lengthening Nail.

INTRODUCTION: Femoral lengthening is performed by distraction osteogenesis via lengthening over a nail (LON) or by using a magnetic lengthening nail (MLN). MLN avoids the complications of external fixation while providing accurate and easily controlled lengthening. However, the increased cost of implants has led many to question whether MLN is cost-effective compared with LON. METHODS: A retrospective review was performed comparing consecutive femoral lengthenings using either LON (n = 19) or MLN (n = 39). The number of surgical procedures, time to union, and amount of lengthening were compared. Cost analysis was performed using both hospital and surgeon payments. Costs were adjusted for inflation using the Consumer Price Index. RESULTS: No difference was observed in the length of femoral distraction. Patients treated with MLN underwent fewer surgeries (3.1 versus 2.1; P < 0.001) and had a shorter time to union (136.7 versus 100.2 days; P = 0.001). Total costs were similar ($50,255 versus $44,449; P = 0.482), although surgeon fees were lower for MLN ($4,324 versus $2,769; P < 0.001). DISCUSSION: Although implants are more expensive for MLN than LON, this appears to be offset by fewer procedures. Overall, the two procedures had similar total costs, but MLN was associated with a decreased number of procedures and shorter time to union. LEVEL OF EVIDENCE: III.

Rapid Diagnostic for Point-of-Care Malaria Screening.

Despite significant success in therapeutic development, malaria remains a widespread and deadly infectious disease in the developing world. Given the nearly 100% efficacy of current malaria therapeutics, the primary barrier to eradication is lack of early diagnosis of the infected population. However, there are multiple strains of malaria. Although significant efforts and resources have been invested in developing antibody-based diagnostic methods for Plasmodium falciparum, a rapid and easy to use screening method capable of detecting all malaria strains has not been realized. Yet, until the entire malaria-infected population receives treatment, the disease will continue to impact society. Here, we report the development of a portable, magneto-optic technology for early stage malaria diagnosis based on the detection of the malaria pigment, hemozoin. Using ß-hematin, a hemozoin mimic, we demonstrate detection limits of <0.0081 µg/mL in 500 µL of whole rabbit blood with no additional reagents required. This level corresponds to <26 parasites/µL, a full order of magnitude below clinical relevance and comparable to or less than existing technologies.

Portable, one-step, and rapid GMR biosensor platform with smartphone interface.

Quantitative immunoassay tests in clinical laboratories require trained technicians, take hours to complete with multiple steps, and the instruments used are generally immobile-patient samples have to be sent in to the labs for analysis. This prevents quantitative immunoassay tests to be performed outside laboratory settings. A portable, quantitative immunoassay device will be valuable in rural and resource-limited areas, where access to healthcare is scarce or far away. We have invented Eigen Diagnosis Platform (EDP), a portable quantitative immunoassay platform based on Giant Magnetoresistance (GMR) biosensor technology. The platform does not require a trained technician to operate, and only requires one-step user involvement. It displays quantitative results in less than 15min after sample insertion, and each test costs less than US$4. The GMR biosensor employed in EDP is capable of detecting multiple biomarkers in one test, enabling a wide array of immune diagnostics to be performed simultaneously. In this paper, we describe the design of EDP, and demonstrate its capability. Multiplexed assay of human immunoglobulin G and M (IgG and IgM) antibodies with EDP achieves sensitivities down to 0.07 and 0.33 nanomolar, respectively. The platform will allow lab testing to be performed in remote areas, and open up applications of immunoassay testing in other non-clinical settings, such as home, school, and office.

An economic passive sampling method to detect particulate pollutants using magnetic measurements.

Identifying particulate matter (PM) emitted from industrial processes into the atmosphere is an important issue in environmental research. This paper presents a passive sampling method using simple artificial samplers that maintains the advantage of bio-monitoring, but overcomes some of its disadvantages. The samplers were tested in a heavily polluted area (Linfen, China) and compared to results from leaf samples. Spatial variations of magnetic susceptibility from artificial passive samplers and leaf samples show very similar patterns. Scanning electron microscopy suggests that the collected PM are mostly in the range of 2-25 µm; frequent occurrence of spherical shape indicates industrial combustion dominates PM emission. Magnetic properties around power plants show different features than other plants. This sampling method provides a suitable and economic tool for semi-quantifying temporal and spatial distribution of air quality; they can be installed in a regular grid and calibrate the weight of PM.

Magnetic controlled growth rods versus conventional growing rod systems in the treatment of early onset scoliosis: a cost comparison.

PURPOSE: To evaluate the cost differences between a conventional growth rod system (CGRS) and magnetic controlled growth rods (MCGR) in treating early onset scoliosis (EOS) over a projected 5 year period. We hypothesise that the high initial outlay for MCGR would be recouped from fewer admissions and surgical procedures over the lifetime of the implant. METHODS: The costs of all aspects of treatment for 14 patients undergoing conversion from CGRS to MGRS were collected over a 3 year period. The costs of all aspects of each treatment including clinic visits, hospital stay, theatre and complications were calculated and projected over the lifetime of each device. RESULTS: The initial outlay for insertion for MCGR was £12,913 more than the CGRS. There were significant cost savings for each lengthening which projected over the 5 year lifetime amounted to a cost saving of over £8,000 per patient. CONCLUSIONS: Magnetic controlled growth rods reduce the need for multiple invasive procedures in the management of EOS. The implant has a significant projected cost saving in comparison to CGRS.

Botryococcus braunii cells: ultrasound-intensified outdoor cultivation integrated with in situ magnetic separation.

An integrated system combining ultrasound-intensified outdoor cultivation of Botryococcus braunii with in situ magnetic harvesting of the algal cells was developed. The algal cells were cultivated in 200 L plastic bag reactors, and seven five-minute ultrasonic treatments at a four-day interval using a fixed frequency of 40 kHz and a total power of 300 W improved algal cell biomass and hydrocarbon productivity. The algal cells were harvested using functional magnetic particles and a magnetic separator, and a recovery efficiency of 90% was obtained under continuous operation at a flow rate of 100mL/min using the in situ magnetic separation system. The overall production cost using the integrated system was US$ 25.14 per kilogram of B. braunii dry biomass. The system developed in this study provides a base for the industrial production of B. braunii.

Turn-on chemiluminescent sensing platform for label-free protease detection using streptavidin-modified magnetic beads.

We report a label-free streptavidin-modified magnetic beads (SA-MBs)-based sensing platform for turn-on chemiluminescent (CL) detection of protease using trypsin as model analyte. In the assay, a biotinylated peptide containing an arginine and a terminal cysteine was used as the substrate of trypsin. Upon adding the peptide into a basic luminol-NaIO4 solution, the terminal cysteine induced a strong CL signal. Surprisingly a much lower CL was emitted when the peptide was immobilized on the surface of SA-MBs. Based on this phenomenon, we designed a turn-on CL sensing system for protease using trypsin as model and its inhibitors screening. In the absence of trypsin, the peptide was coupled to the SA-MBs surface, resulting in a low CL background. Upon the addition of trypsin, the peptide can be catalytically hydrolyzed at the C-terminus of arginine, resulting in the formation of free cysteine-containing residues and subsequent CL recovery with the addition of luminol and NaIO4. The simple method does not require washing or separating procedures. Trypsin at a concentration as low as 10 pM can be assayed using this new CL sensing system. Additionally, the proposed method can be employed for screening the inhibitors of trypsin. This new sensing strategy could be easily extended to assay other proteases by simply changing the peptide substrate.

Low-field permanent magnets for industrial process and quality control.

In this review we focus on the technology associated with low-field NMR. We present the current state-of-the-art in low-field NMR hardware and experiments, considering general magnet designs, rf performance, data processing and interpretation. We provide guidance on obtaining the optimum results from these instruments, along with an introduction for those new to low-field NMR. The applications of lowfield NMR are now many and diverse. Furthermore, niche applications have spawned unique magnet designs to accommodate the extremes of operating environment or sample geometry. Trying to capture all the applications, methods, and hardware encompassed by low-field NMR would be a daunting task and likely of little interest to researchers or industrialists working in specific subject areas. Instead we discuss only a few applications to highlight uses of the hardware and experiments in an industrial environment. For details on more particular methods and applications, we provide citations to specialized review articles.

Magnetic navigation system and CT roadmap-assisted percutaneous coronary intervention: a comparison to the conventional approach.

BACKGROUND: Computed tomography coronary angiography (CTCA) has been successfully integrated with the magnetic navigation system (MNS) to facilitate a roadmap-assisted percutaneous coronary intervention (PCI). The aim of this study was to compare this new approach of PCI versus conventional PCI regarding the difference of contrast usage, x-ray exposure, procedure success, and in-hospital expenses. METHODS: Thirty-eight patients with stable coronary artery disease and coronary artery lesions of ≥70% diameter stenosis diagnosed by both pre-procedure CTCA and coronary angiography (CAG) were enrolled to receive the MNS and CT roadmap-assisted PCI. Another 38 patients were consecutively recruited to receive conventional PCI, matched with the MNS group by the vessel and lesion type base on American College of Cardiology/American Heart Association criteria. RESULTS: Regarding the process of the guidewire placement, wherein the technical difference of the two procedures exists, the median contrast usage for guidewire crossing was significantly lower in the MNS group than in the conventional group [0.0 mL (interquartile range [IQR], 0.0-3.0 mL) vs 5.0 mL (IQR, 3.1-6.8 mL); P<.001], with zero contrast usage in 25 of the 44 guidewire placements in the MNS group, but in none of the conventional group; the radiation dosage for guidewire crossing in the MNS group was also significantly lower than in the conventional group (235.8 µGym² [IQR, 134.9-455.1 µGym²] vs 364.4 µGym² [IQR, 223.4-547.2 µGym²]; P=.033). There were no significant differences between the two groups concerning the total contrast usage, total radiation dosage of the PCI, the procedural fees, or the overall in-hospital expenses. All of the enrolled vessels were successfully intervened in both groups. CONCLUSION: In PCI of simple lesions, the application of CT guidance and magnetic navigation had modest impacts on radiation dosage and contrast usage for wire crossing, but no impact on overall radiation dosage or contrast usage for the procedure. In addition, the use of CT roadmap and MNS was likely more expensive compared to PCI using conventional radiographic technique.

Fabrication of a magnet-assisted alignment device for the amperometric detection of capillary electrophoresis using a carbon nanotube/polypropylene composite electrode.

A magnet-assisted alignment device was designed and fabricated for the amperometric detection of CE. It mainly consisted of a magnet-containing electrode holder, a capillary-based microdisc detection electrode, a detection cell, and a micrometer adjuster. To demonstrate the feasibility and performance of the alignment device, it was used in combination with a carbon nanotube/polypropylene (CNT/PP) composite electrode for the determination of p-phenylenediamine, m-aminophenol, and m-dihydroxybenzene in commercial hair dye by CE. The CNT-based electrode was fabricated by packing a melt mixture of CNTs and PP in a piece of fused silica capillary under heat, offering significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, and high resistance to surface fouling. Because magnetic force was employed to move the detection electrode, the alignment system was significantly simplified. It is characterized by simple design and fabrication, high alignment reproducibility, reduced alignment time, and low cost. Both the alignment device and the CNT/PP composite electrode should find a wide range of applications in microchip CE, flowing injection analysis, and other microfluidic analysis systems.

Digital microfluidic magnetic separation for particle-based immunoassays.

We introduce a new format for particle-based immunoassays relying on digital microfluidics (DMF) and magnetic forces to separate and resuspend antibody-coated paramagnetic particles. In DMF, fluids are electrostatically controlled as discrete droplets (picoliters to microliters) on an array of insulated electrodes. By applying appropriate sequences of potentials to these electrodes, multiple droplets can be manipulated simultaneously and various droplet operations can be achieved using the same device design. This flexibility makes DMF well-suited for applications that require complex, multistep protocols such as immunoassays. Here, we report the first particle-based immunoassay on DMF without the aid of oil carrier fluid to enable droplet movement (i.e., droplets are surrounded by air instead of oil). This new format allowed the realization of a novel on-chip particle separation and resuspension method capable of removing greater than 90% of unbound reagents in one step. Using this technique, we developed methods for noncompetitive and competitive immunoassays, using thyroid stimulating hormone (TSH) and 17ß-estradiol (E2) as model analytes, respectively. We show that, compared to conventional methods, the new DMF approach reported here reduced reagent volumes and analysis time by 100-fold and 10-fold, respectively, while retaining a level of analytical performance required for clinical screening. Thus, we propose that the new technique has great potential for eventual use in a fast, low-waste, and inexpensive instrument for the quantitative analysis of proteins and small molecules in low sample volumes.

Environmental friendly crush-magnetic separation technology for recycling metal-plated plastics from end-of-life vehicles.

Metal-plated plastics (MPP), which are important from the standpoint of aesthetics or even performance, are increasingly employed in a wide variety of situations in the automotive industry. Serious environmental problems will be caused if they are not treated appropriately. Therefore, recycling of MPP is an important subject not only for resource recycling but also for environmental protection. This work represents a novel attempt to deal with the MPP. A self-designed hammer crusher was used to liberate coatings from the plastic substrate. The size distribution of particles was analyzed and described by the Rosin-Rammler function model. The optimum retaining time of materials in the crusher is 3 min. By this time, the liberation rate of the materials can reach 87.3%. When the density of the suspension is 31,250 g/m(3), the performance of liberation is the best. Two-step magnetic separation was adopted to avoid excessive crushing and to guarantee the quality of products. Concerning both the separation efficiency and grade of products, the optimum rotational speed of the magnetic separator is 50-70 rpm. On the basis of the above studies about the liberating and separating behavior of the materials, a continuous recycling system (the technology of crush-magnetic separation) is developed. This recycling system provides a feasible method for recycling MPP efficiently, economically, and environmentally.

Facile and rapid magnetic relaxation switch immunosensor for endocrine-disrupting chemicals.

In order to develop facile, fast and sensitive detection methods for endocrine-disrupting chemicals (EDCs), we described a sensitive biosensing system involving magnetic relaxation switch, based on the assembly of cross-linked superparamagnetic iron oxide (CLIO) nanoparticles induced by the antigen-antibody biorecognition. The design of smart CLIO-based superparamagnetic iron oxide nanoparticles and antigen-OVA was described for the detection of bisphenol A [2,2-bis (4-hydroxyphenol) propane (BPA)]. The addition of BPA to the rapid magnetic relaxation switch immunosensor led to transverse relaxation time (T2) shortening compared to a blank control as shown by NMR relaxometry measurements. This process was also applied to the rapid and facile determination of concentrations of BPA in drinking water (tap water). Good linearity for all calibration curves was obtained, and the limit of detection (LOD) for BPA was 0.4 ng/mL in tap water.

Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient.

A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy efficiency in the total energy lifecycle, has accelerated research into energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the efficiency and performance of devices in electric power generation, conditioning, conversion, transportation, and other energy-use sectors of the economy. This review focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials, with an emphasis on their optimization for energy applications. Specifically, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, are discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure-property relationships, are discussed in the context of their respective markets, as well as their potential impact on energy efficiency. Finally, considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed.

Single-tube analysis of DNA methylation with silica superparamagnetic beads.

BACKGROUND: DNA promoter methylation is a signature for the silencing of tumor suppressor genes. Most widely used methods to detect DNA methylation involve 3 separate, independent processes: DNA extraction, bisulfite conversion, and methylation detection via a PCR method, such as methylation-specific PCR (MSP). This method includes many disconnected steps with associated losses of material, potentially reducing the analytical sensitivity required for analysis of challenging clinical samples. METHODS: Methylation on beads (MOB) is a new technique that integrates DNA extraction, bisulfite conversion, and PCR in a single tube via the use of silica superparamagnetic beads (SSBs) as a common DNA carrier for facilitating cell debris removal and buffer exchange throughout the entire process. In addition, PCR buffer is used to directly elute bisulfite-treated DNA from SSBs for subsequent target amplifications. The diagnostic sensitivity of MOB was evaluated by methylation analysis of the CDKN2A [cyclin-dependent kinase inhibitor 2A (melanoma, p16, inhibits CDK4); also known as p16(INK4a)] promoter in serum DNA of lung cancer patients and compared with that of conventional methods. RESULTS: Methylation analysis consisting of DNA extraction followed by bisulfite conversion and MSP was successfully carried out within 9 h in a single tube. The median pre-PCR DNA yield was 6.61-fold higher with the MOB technique than with conventional techniques. Furthermore, MOB increased the diagnostic sensitivity in our analysis of the CDKN2A promoter in patient serum by successfully detecting methylation in 74% of cancer patients, vs the 45% detection rate obtained with conventional techniques. CONCLUSIONS: The MOB technique successfully combined 3 processes into a single tube, thereby allowing ease in handling and an increased detection throughput. The increased pre-PCR yield in MOB allowed efficient, diagnostically sensitive methylation detection.

Comparison of magnetically navigated and conventional wire percutaneous coronary intervention of a single discrete stenosis.

OBJECTIVE: The objective of this study is to compare magnetic guidewire navigation in percutaneous coronary intervention (MPCI) to conventional percutaneous coronary intervention (CPCI) for the elective treatment of a single discrete stenosis. BACKGROUND: Magnetic navigation actively steers an angioplasty wire-tip and may improve PCI procedures, but it is not known whether the intricacy and increased preparation necessary for using the system negatively influences the performance of simple procedures in terms of time and contrast use. METHODS: The procedures of 44 patients (mean age 65 +/- 10 year) undergoing elective single vessel MPCI of a single discrete stenosis were matched for age, gender, and lesion location with 44 concurrent patients (mean age 65 +/- 10 year) undergoing CPCI. The major endpoint was procedural time. RESULTS: Technical success was defined as an intraluminal wire position distal to the stenosis. Procedural outcome, contrast use, and costs were evaluated. Clinical demographics and angiographic characteristics of the two groups were similar, except for a higher incidence of previous MI and class III angina pectoris in the conventional group. The technical success rate was high and identical in both groups (97.7%). Procedural and fluoroscopy times were not significantly different for MPCI compared to CPCI (21.0 +/- 14.5 min vs. 24.7 +/- 14.0 min; 4.9 +/- 4.8 min vs. 7.3 +/- 10.3 min, P = NS). There was a significant reduction in median contrast use [60 ml/patient (41-100) vs. 100 ml/patient (64-130); P = 0.006]. CONCLUSION: Magnetic navigation does not increase procedural time, irradiation, equipment use, or cost compared to conventional PCI of a single discrete stenosis. It proved feasible, yielding high rates of procedural success with less contrast use.

Magnetically navigated percutaneous coronary intervention in distal and/or complex lesions may improve procedural outcome and material consumption.

AIMS: Comparison of magnetic guidewire navigation in percutaneous coronary intervention (magnetic PCI) across distal and/or complex lesions versus conventional navigation (conventional PCI). METHODS AND RESULTS: Forty-seven consecutive patients (age 61 +/- 10 yr) undergoing elective single vessel magnetic PCI for distal and/or complex lesions were matched by age and lesion location with 45 patients undergoing conventional PCI (age 63 +/- 10 yr). Technical success rate was defined as an intraluminal wire position distal to the stenosis. Procedural outcome and costs were evaluated. Baseline demographics and angiographic characteristics of the two groups were similar. The technical success rate did not differ between magnetic and conventional PCI (95.7 vs 97.8%; p = 1.00). Significantly shorter procedural and fluoroscopy time were observed for magnetic compared to conventional PCI (29.9 +/- 17.6 vs 41.1 +/- 21 min, p = 0.007; 7.5 +/- 7.3 vs 16.1 +/- 22.4 min, p = 0.02 respectively). Less contrast was used in the magnetic PCI group (58 ml/patient; P = 0.02). These advantages resulted in a mean estimated saving of 1400 euro per patient (P < 0.001). Advantages of procedural outcome were even more pronounced in the ACC/AHA lesion class C subgroup. CONCLUSIONS: Magnetic compared to conventional PCI is an attractive novel technique that proved to be feasible and safe and might be faster in distal and especially complex lesions.