Nowadays, the most commonly used fixation systems are non-resorbable, but new resorbable magnesium alloy fixation screws have been introduced recently. Therefore, the aim of this study was to compare ...the magnesium fixation screw and the commonly used non-resorbable titanium screw in an animal model. Four 3-wall defect sites were covered with collagen membranes in the mandible of twenty beagle dogs (two sites on the left and two on the right). Each membrane was fixed with either four magnesium screws or four titanium screws. Post-operative follow-up revealed the expected observations such as transient inflammation and pain. Both groups showed a good healing response, with no differences between groups. Micro-CT analysis showed no significant difference between groups in terms of BV/TV or soft tissue volume. The void volume in the magnesium fixation screw group continued to decrease on average between the different timepoints, but not significantly. Furthermore, a gradual progression of the degradation process of the magnesium screws was observed in the same group. Magnesium screws and titanium screws showed equal performance in tissue regeneration according to GBR principles. An additional advantage of magnesium screws is their resorbable nature, which eliminates the need for a second surgical step to remove the screws.
Barrier membranes are commonly used as part of the dental surgical technique guided bone regeneration (GBR) and are often made of resorbable collagen or non-resorbable materials such as PTFE. While ...collagen membranes do not provide sufficient mechanical protection of the covered bone defect, titanium reinforced membranes and non-resorbable membranes need to be removed in a second surgery. Thus, biodegradable GBR membranes made of pure magnesium might be an alternative. In this study a biodegradable pure magnesium (99.95%) membrane has been proven to have all of the necessary requirements for an optimal regenerative outcome from both a mechanical and biological perspective. After implantation, the magnesium membrane separates the regenerating bone from the overlying, faster proliferating soft tissue. During the initial healing period, the membrane maintained a barrier function and space provision, whilst retaining the positioning of the bone graft material within the defect space. As the magnesium metal corroded, it formed a salty corrosion layer and local gas cavities, both of which extended the functional lifespan of the membrane barrier capabilities. During the resorption of the magnesium metal and magnesium salts, it was observed that the membrane became surrounded and then replaced by new bone. After the membrane had completely resorbed, only healthy tissue remained. The in vivo performance study demonstrated that the magnesium membrane has a comparable healing response and tissue regeneration to that of a resorbable collagen membrane. Overall, the magnesium membrane demonstrated all of the ideal qualities for a barrier membrane used in GBR treatment.
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•First report on a biodegradable metallic barrier membrane for use in oral surgery is presented.•The mechanical stability of the metallic barrier membrane provides a careful shielding of the augmented bone defect.•Full resorption of metallic barrier membrane and bone healing is completed long before current standards for second surgical patient treatment.
An ideal fixation system for guided bone (GBR) regeneration in oral surgery must fulfil several criteria that includes the provision of adequate mechanical fixation, complete resorption when no ...longer needed, complete replacement by bone, as well as be biocompatible and have a good clinical manageability. For the first time, a biodegradable magnesium fixation screw made of the magnesium alloy WZM211 with a MgF2 coating has been designed and tested to fulfill these criteria. Adequate mechanical fixation was shown for the magnesium fixation screw in several benchtop tests that directly compared the magnesium fixation screw with an equivalent polymeric resorbable device. Results demonstrated slightly superior mechanical properties of the magnesium device in comparison to the polymeric device even after 4 weeks of degradation. Biocompatibility of the magnesium fixation screw was demonstrated in several in vitro and in vivo tests. Degradation of the magnesium screw was investigated in in vitro and in vivo tests, where it was found that the screw is resorbed slowly and completely after 52 weeks, providing adequate fixation in the early critical healing phase. Overall, the magnesium fixation screw demonstrates all of the key properties required for an ideal fixation screw of membranes used in guided bone regeneration (GBR) surgeries.
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•The first comprehensive report on experimental data for a biodegradable metallic fixation pin for use in oral surgery is presented.•Results demonstrated superior mechanical properties of the Mg fixation pin in comparison to the polymeric pin even after 4 weeks of degradation.•The MgF2 coated Mg pin made of alloy WZM211 has a slow corrosion rate with a service time of 4 weeks and is fully resorped at 52 weeks after implantation.
For the surgical technique of guided bone regeneration (GBR), the choice of available barrier membranes has until recently not included an option that is mechanically strong, durable, synthetic and ...resorbable. The most commonly used resorbable membranes are made from collagen, which are restricted in their mechanical strength. The purpose of this study is to evaluate the degradation and regeneration potential of a magnesium membrane compared to a collagen membrane. In eighteen beagle dogs, experimental bone defects were filled with bovine xenograft and covered with either a magnesium membrane or collagen membrane. The health status of the animals was regularly monitored and recorded. Following sacrifice, the hemimandibles were prepared for micro-CT (μ-CT) analysis. Complications during healing were observed in both groups, but ultimately, the regenerative outcome was similar between groups. The μ-CT parameters showed comparable results in both groups in terms of new bone formation at all four time points. In addition, the μ-CT analysis showed that the greatest degradation of the magnesium membranes occurred between 1 and 8 weeks and continued until week 16. The proportion of new bone within the defect site was similar for both treatment groups, indicating the potential for the magnesium membrane to be used as a viable alternative to collagen membranes. Overall, the new magnesium membrane is a functional and safe membrane for the treatment of defects according to the principles of GBR.
•Operation strategies of a hybrid storage system within PCR market were analyzed.•Based on optimization the most profitable sizing of each technology were find.•The influence on energy and ...performance with a power to heat system were examined.•Meaningful system variables for different technologies and setups are analyzed.
The main goal of this research work is the optimal dimensioning of battery storage systems. In particular, a combination of lithium-ion and lead-acid battery systems, participating on the primary frequency control market, are considered. Because the fall in market prices the profitability is also falling. To enhance the economy of a battery system, a power distribution strategy are developed. In the first, two different approaches of power deviation between the lithium-ion and lead-acid battery system are evaluated. Based on the results of this first approach, the most profitable dimensioning was determined by using an optimization algorithm. The second approach comprised the coupling of the battery systems with a power-to-heat unit. Besides the new economic potential of this second approach, this combination allows a new operation strategy, which was also analyzed. For both cases, the optimal battery capacity with high profitability, depending on trading standards and regulations as well as on operation strategy, was determined.
BACKGROUND: Overweight is a complex trait in which both environmental and genetic factors play a role. OBJECTIVE: We aimed to evaluate the influence of common genetic variants identified by ...genome-wide association studies on overweight and the metabolic profile in adolescence. DESIGN: In a population-based cohort of 663 girls and 612 boys aged 16 y, weight, height, skinfold thicknesses, percentage body fat, waist circumference, blood pressure, glucose, insulin, lipid profile, and DNA were obtained. We defined overweight according to international criteria. We performed multiple linear and logistic regression analyses to assess the influence of candidate single nucleotide polymorphisms near the INSIG2, in the FTO, and near the MC4R genes and repeated-measures analyses of available body mass index (BMI) and skinfold thickness data across 3 visits at ages 11, 13.5, and 16 y. RESULTS: A total of 15.1% of participants were overweight or obese at age 16 y. No associations with INSIG2 were found. Common variation in the FTO gene was associated with sex-specific z scores of BMI (B: 0.11; 95% CI: 0.03, 0.19), sum of skinfold thicknesses (B: 0.12; 95% CI: 0.04, 0.20), percentage body fat (B: 0.11; 95% CI: 0.03, 0.19), waist circumference (B: 0.11; 95% CI: 0.03, 0.19), fasting glucose (B: 0.10; 95% CI: 0.00, 0.20), and overweight (odds ratio: 1.34; 95% CI: 1.06, 1.69) at age 16 y. Repeated-measures analyses confirmed the associations for BMI and sum of skinfold thicknesses, and physical activity did not modify these associations. Common variation near the MC4R gene was associated with BMI in cross-sectional (B: 0.11; 95% CI: 0.02, 0.20) and repeated-measures (B: 0.12; 95% CI: 0.03, 0.20) analyses. CONCLUSIONS: Common variation in the FTO gene is associated with overall and abdominal adiposity. Variation near the MC4R gene is associated with BMI. These findings in adolescents strengthen and extend the results from previous research.
The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10−14 – 10−10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT′1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or “hot-spot” neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10-14 – 10-10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT'1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or "hot-spot" neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
Background: Overweight is a complex trait in which both environmental and genetic factors play a role.
Objective: We aimed to evaluate the influence of common genetic variants identified by ...genome-wide association studies on overweight and the metabolic profile in adolescence.
Design: In a population-based cohort of 663 girls and 612 boys aged 16 y, weight, height, skinfold thicknesses, percentage body fat, waist circumference, blood pressure, glucose, insulin, lipid profile, and DNA were obtained. We defined overweight according to international criteria. We performed multiple linear and logistic regression analyses to assess the influence of candidate single nucleotide polymorphisms near the INSIG2, in the FTO, and near the MC4R genes and repeated-measures analyses of available body mass index (BMI) and skinfold thickness data across 3 visits at ages 11, 13.5, and 16 y.
Results: A total of 15.1% of participants were overweight or obese at age 16 y. No associations with INSIG2 were found. Common variation in the FTO gene was associated with sex-specific z scores of BMI (B: 0.11; 95% CI: 0.03, 0.19), sum of skinfold thicknesses (B: 0.12; 95% CI: 0.04, 0.20), percentage body fat (B: 0.11; 95% CI: 0.03, 0.19), waist circumference (B: 0.11; 95% CI: 0.03, 0.19), fasting glucose (B: 0.10; 95% CI: 0.00, 0.20), and overweight (odds ratio: 1.34; 95% CI: 1.06, 1.69) at age 16 y. Repeated-measures analyses confirmed the associations for BMI and sum of skinfold thicknesses, and physical activity did not modify these associations. Common variation near the MC4R gene was associated with BMI in cross-sectional (B: 0.11; 95% CI: 0.02, 0.20) and repeated-measures (B: 0.12; 95% CI: 0.03, 0.20) analyses.
Conclusions: Common variation in the FTO gene is associated with overall and abdominal adiposity. Variation near the MC4R gene is associated with BMI. These findings in adolescents strengthen and extend the results from previous research.
To investigate whether the diagnostic accuracy of unenhanced computed tomography (CT) regarding the differentiation of adrenal adenomas from adrenal metastases is increased by applying a combination ...of morphologic criteria instead of only measuring the density values of the tumor.
Unenhanced CT scans of 56 patients with an adrenal mass and a history of an extra-adrenal malignancy were analyzed for size, attenuation, contour, and structure characteristics of the adrenal tumor. Coefficients yielded by multiple logistic regression analysis were used for the construction of an additive total score (score S) that included several diagnostic criteria. The reliability of the total score and all parameter combinations was tested by receiver operating characteristic (ROC) analysis. The nature of the adrenal lesion was determined by follow-up CT (40 patients), percutaneous biopsy (15 patients), or surgery (1 patient). Twenty-four of the neoplasms were adenomas, and 32 were found to be metastases.
The score of the combined CT parameters showed the largest area under the ROC curve. The highest predictive power indicated by the model was calculated at a cutoff value of 7.05, with a sensitivity of 100% and a specificity of 96.8% for the detection of metastases. At 6.85 points as the cutoff value, the scoring system still maintained a sensitivity of 95.8% and a specificity of 96.9%.
The differentiation between adrenal adenomas and metastases is improved by applying our scoring system compared with any single parameter alone. The total score is obtained by adding 10% of the density values to the size in centimeters, plus 2 if the contour of the lesion is blurred and plus 1 if the structure is inhomogeneous. By setting the threshold at 7 points, all but 1 lesion were classified correctly.
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