Pin Configuration Research Articles

The Influence of Sagittal Pin Angulation on the Stiffness and Pull-Out Strength of a Monolateral Fixator Construct.

Monolateral pin-to-bar-clamp fixators are commonly used to stabilize acute extremity injuries. Certain rules regarding frame geometry have been established that affect construct stability. The influence of sagittal pin angulation on construct stiffness and strength has not been investigated. The purpose of this biomechanical study was to demonstrate the effect of a pin angulation in the monolateral fixator using a composite cylinder model. Three groups of composite cylinder models with a fracture gap were loaded with different mounting variants of monolateral pin-to-bar-clamp fixators. In the first group, the pins were set parallel to each other and perpendicular to the specimen. In the second group, both pins were set convergent each in an angle of 15° to the specimen. In the third group, the pins were set each 15° divergent. The strength of the constructions was tested using a mechanical testing machine. This was followed by a cyclic loading test to produce pin loosening. A pull-out test was then performed to evaluate the strength of each construct at the pin-bone interface. Initial stiffness analyses showed that the converging configuration was the stiffest, while the diverging configuration was the least stiff. The parallel mounting showed an intermediate stiffness. There was a significantly higher resistance to pull-out force in the diverging pin configuration compared to the converging pin configuration. There was no significant difference in the pull-out strength of the parallel pins compared to the angled pin pairs. Convergent mounting of pin pairs increases the stiffness of a monolateral fixator, whereas a divergent mounting weakens it. Regarding the strength of the pin-bone interface, the divergent pin configuration appears to provide greater resistance to pull-out force than the convergent one. The results of this pilot study should be important for the doctrine of fixator mounting as well as for fixator component design.

Tuning the pin configuration on cold plate for better thermal management of lithium-ion battery

Enhancing cooling performance with the lowest pressure drop characteristics is a persistent problem in battery thermal management systems. The present investigation discusses the design of cooling plate pin configuration, especially for the fast charging–discharging operation of lithium-ion batteries. At first, the effect of pin geometrical configurations, viz. triangular, square, circular and elliptical, are studied for thermohydraulic characteristics. Further, orientation of the pin is investigated for normal and thermal runaway conditions. Furthermore, the effect of discharge rate and flow direction on thermal runaway behavior is also analyzed. Our results reveal that introducing pin on the cooling plate is desirable for better battery thermal management and keeping the battery surface temperature within safety guidelines. Further, the elliptical pin on the cooling plate is found to result in the least pressure drop (+80.46%) among pin configurations considered. The temperature of battery surface is found to be minimum when the pins are oriented at an angle of 90° to a flow direction of 180°, which is recommended particularly for the operation of the battery under thermal runaway. Furthermore, the pin configuration maintained cell surface temperature below 22°C and 75°C during normal and thermal runaway conditions, respectively. Moreover, the maximum pressure drop is found to be 225 and 136 kPa during normal and thermal runaway conditions, respectively.

Finite element analysis of Kirschner wire fixation for lateral condyle fracture in children in the sagittal plane.

This study aims to find the optimal arrangement of the Kirschner wire (K-wire) in the sagittal plane for fixation of a pediatric lateral condylar humeral fracture (Milch type II) by using finite element analysis (FEA). A model of lateral condyle fracture in a 6-year-old boy was developed, and an XYZ coordinate system was established based on this model. The YZ plane was defined as the sagittal plane to investigate the impact of the angle formed by the first and second K-wires on stability. Two configurations were studied for each angle: parallel and divergent. Evaluation indicators included the maximum displacement of the fracture fragment and the maximum von Mises stress in the pins and bone. The model with a -60° angle showed the best performance in both evaluation indicators. The parallel and divergent pin configurations had different performances in each group. The displacement results for negative angles were similar, and this result was better than those for positive angles. We successfully created a model of pediatric lateral condyle humerus fracture (Milch type II) and performed K-wire fixation with varying sagittal plane configurations, combined with FEA. Our findings demonstrate that the angle of -60° between the two pins in the sagittal plane provided the highest level of stability, with divergent configurations proving superior to parallel pinning at this angle.

Numerical and parametric study on fracture behaviour and effect of friction on resistance of aluminium alloy shear connections

Fastener pre-tension is commonly used in the practical cases of aluminium alloy bearing-type connections with friction provided by treated surfaces. However, research on the effect of friction on the ultimate resistance is currently limited. In this paper, a numerical investigation on the structural performance and design of aluminium alloy double shear connections fastened by preloaded stainless steel swage-locking pins is presented. Finite element (FE) models were developed using Abaqus explicit dynamic packages and validated against the tests conducted previously. Prior to the numerical modelling of shear connections, the framework of aluminium alloy material properties has been studied. In order to simulate the full-range stress–strain relations and the failure of the tested aluminium alloys, two damage models were evaluated. The adopted model was then used to simulate the fracture occurred at the peak load or the post-peak stage in the double shear connection tests, and investigate their failure mechanism of bearing, shear-out and end-splitting. Upon validation, an extensive parametric study of 330 shear connections was conducted to investigate the effect of friction and pin configuration on the structural performance of shear connections made of different aluminium alloy grades. The values of the friction and pin hole resistance at the ultimate loads were comprehensively discussed. The numerically derived ultimate resistances were also compared with the current design equations, which were shown to provide conservative and scattered results due to the lack of consideration of the friction effect. A new design method was proposed with the friction effect incorporated, resulting in accurate predictions of ultimate resistance for aluminium alloy shear connections with preloaded stainless steel swage-locking pins.

Factors Influencing Functional Outcomes in Supracondylar Humerus Fractures: A Retrospective Study of Paediatric Patients in a Level One Trauma Centre.

Background The outcomes after fixation of the supracondylar humerus fracture (SCHF) are not documented in the current literature. In our study, we endeavour to determine the factors that influence the functional outcome and gauge their respective impact. Methodology We retrospectively reviewed the outcomes of patients who presented to our tertiary care centre (Royal London Hospital) with SCHFs between September 2017 and February 2018. We analysed patient records to assess several clinical parameters, including age, Gartland's classification, comorbidities, time to treatment, and fixation configuration. We conducted a multiple linear regression analysis to determine each of the clinical parameter's impact on the functional and cosmetic outcome, as reflected in Flynn's criteria. Results We included 112 patients in our study. Pediatric SCHFs had good functional outcomes based on Flynn's criteria. There was no significant statistical difference in functional outcomes with respect to sex (p= 0.713), age (p= 0.96), fracture type (p= 0.14), K-wire configuration (p=0.83), and time elapsed since surgery (p= 0.240). Conclusions Our results demonstrate that good functional outcomes can be expected with paediatric SCHFs based on Flynn's criteria, regardless of age at injury, sex, or pin configuration, provided satisfactory reduction is achieved and maintained. The only variable with statistical significance was Gartland's grade; Grades III and IV were correlated with poorer outcomes.

Validation and application of the Dragon5 lattice code for neutronics and burnup analysis of VVER-1000 pin cell and assembly model

This work deals with the validation and assessment of neutronics and burnup analysis capacity of the deterministic lattice code Dragon5 for VVER-1000 hexagonal pin and assembly model configuration. Various VVER-1000 hexagonal pin-cell benchmark cases including the fresh uranium fuel and mixed oxide fuel of ORNL are simulated and compared with the HELIOS and OpenMC code. The data library differences of certain nuclides will lead to large deviations of the results. Accurate results can be presented by the Dragon5 lattice code when compared with OpenMC code. The OECD LEU and MOX assembly benchmarks are computed to further validate the prediction ability for VVER-1000 assembly, reasonable agreement between Dragon5 solutions and published values of other codes is observed for burnup parameters including infinite multiplication factors, concentrations of important actinides and fission product nuclides. Moreover, the post-irradiation of UO2 sample experiment of the Russian Kalinin-1 VVER-1000 reactor is simulated and compared with laboratory measured values to provide the experiment validation of the Dragon5 lattice code. The predicted concentrations of actinides up to Cm244 are compared with HELIOS and Serpent Monte Carlo code. The results show that the Dragon5 lattice code presents better prediction accuracy for Calculated-to-Experimental ratios (C/E's) of most actinide concentrations than the HELIOS and Serpent code. Therefore, the École Polytechnique de Montréal Dragon5 lattice physics code can be applied to the neutronics and burnup analysis of VVER-1000 hexagonal pin-cell and assembly model.

Extra Lateral Pin or Less Radiation? A Comparison of Two Different Pin Configurations in the Treatment of Supracondylar Humerus Fracture.

Closed reduction and percutaneous fixation are the most commonly used methods in the surgical treatment of supracondylar humerus fractures. The pin configuration changes stability and is still controversial. The aim of this study was to investigate the relationship between surgical duration and radiation dose/duration for different pinning fixations. A total of 48 patients with Gartland type 2, 3, and 4 supracondylar fractures of the humerus were randomized into two groups-2 lateral and 1 medial (2L1M) pin fixation (n = 26) and 1 lateral 1 medial (1L1M) pin fixation (n = 22). A primary assessment was performed regarding surgical duration, radiation duration, and radiation dose. A secondary assessment included clinical outcome, passive range of motion, radiographic measurements, Flynn's criteria, and complications. There were 26 patients in the first group (2L1M) and 22 patients in the second group (1L1M). There was no statistical difference between the groups regarding age, sex, type of fracture, or Flynn's criteria. The overall mean surgical duration with 1L1M fixation (30.59 ± 8.72) was statistically lower (p = 0.001) when compared to the 2L1M Kirschner wire K-wire fixation (40.61 ± 8.25). The mean radiation duration was 0.76 ± 0.33 s in the 1L1M K-wire fixation and 1.68 ± 0.55 s in the 2L1M K-wire fixation. The mean radiation dose of the 2L1M K-wire fixation (2.45 ± 1.15 mGy) was higher than that of the 1L1M K-wire fixation (0.55 ± 0.43 mGy) (p = 0.000). The current study shows that although there is no difference between the clinical and radiological outcomes, radiation dose exposure is significantly lower for the 1L1M fixation method.

Evaluation of the wear-resistance of DLC-coated hard-on-soft pairings for biomedical applications

Diamond-like carbon (DLC) coatings deposited on the articulating surfaces of total hip or knee arthroplasties have the potential to enhance the overall biotribological behavior and longevity. In this contribution, we employ an ultrahigh molecular weight polyethylene ball-on-three cobalt chromium or titanium alloy pin configuration lubricated by simulated body fluid to effectively carry out screening tests. Thus, the influence of the choice of the coated component (metallic and/or polymeric) as well as the differences between a higher and lower load case with non- and conventionally cross-linked polyethylene were studied. The studied coating systems featured excellent mechanical properties with a substantial enhancement of indentation hardness and elastic modulus ratios. The adhesion of the coatings as determined in modified scratch tests can be considered as very good to polymeric and as satisfactory to metallic substrates, thus confirming the potential for the use in total joint arthroplasties. Although the coatings predominantly led to an increase in friction due to the considerably higher roughness, wear was substantially reduced. While only the metallic components were mostly coated in studies reported in literature, our investigation showed that a coating of the polymer component in particular is of decisive importance for enhancing the wear performance and increasing the service life of load-bearing implants. Moreover, single sided coating results in higher wear of the uncoated counter-part. Therefore, coating systems deposited on both articulating surfaces, polymeric and metallic, should be pursued in the future.

Evaluation of Conducted Electromagnetic Interference Behavior of Copper Vapor Laser

High power and high repetition rate electrically excited copper vapor laser (CVL) is a strong source of radiated and conducted electromagnetic interference (EMI). The thermal energy required to raise the temperature (∼1600°C) to generate copper vapor and the required voltage pulse for population inversion is provided by the pulse generating unit (PGU). The PGU generates a voltage pulse of the order of ∼13 kV with a rise time of less than 100 ns and a current pulse in the range of ∼500 A with a similar rise time. The high voltage and current generated by PGU along with the high voltage pulse discharge in the laser tube serves as a prominent source of EMI and affects the performance of nearby electronic devices. This article presents a comprehensive study of conducted EMI from a high-power and high voltage discharge inside the CVL system and its impact on laser performance. The conducted noise from the laser is a function of laser impedance and is proportional to the magnitude of load mismatch. A simple and robust technique is presented to reduce the conducted noise from CVL. The correlation between the laser electrode pin configurations and the conducted noise is also presented.

A self-powered and broadband UV PIN photodiode employing a NiOx layer and a β-Ga2O3 heterojunction

Crucial commercial and space applications require the detection of broadband ultraviolet (UV) rays spanning from UV-A to UV-C. In this study, the authors demonstrate a broadband UV photodetector employing a p-type NiOx layer and an n-type β-Ga2O3 heterostructure in PIN configuration for the first time. Simulations are conducted to optimize the doping concentration and thickness of the NiOx layer, ensuring that (a) a reasonable depletion width is maintained within the NiOx layer for UV-A and UV-B light absorption; (b) anode ohmic contacts are formed on the nondepleted NiOx film, and (c) >70% of the UV-C light is absorbed by β-Ga2O3. The optimized NiOx/β-Ga2O3 PIN photodiode exhibits good responsivity to incident light wavelengths in the UV-A, UV-B, and UV-C regions. While the NiOx layer is considered to be responsible for providing good photoresponsivity in the UV-A and UV-B regions, a highly resistive (near-intrinsic) β-Ga2O3 layer is required for the absorption of incident UV-C light. A record detectivity of >1011 cm Hz0.5 W−1 for the UV-B and UV-C regions and >1010 cm Hz0.5 W−1 for the UV-A region is observed in the NiOx/β-Ga2O3 heterostructure PIN photodiode during the self-powered operation. The results presented in this study are promising and instigate device design strategies for (ultra)wide bandgap semiconductor-based broadband UV PIN photodetectors.

Is Lateral Onset Cross Pin Technique Strong Enough? A Biomechanical Study.

It is aimed to compare biomechanically the 3 different pin techniques and the lateral onset cross-pinning (LXP) technique in supracondylar humeral fractures. Biomechanical testing was performed on 52 synthetic humeriFour pin configurations techniques were tested: crossed pins (XP), 2 lateral pins (2LP), 3 lateral pins (3LP), and LXP technique. Biomechanical testing was performed on Shimadzu Autograph measuring machine. Each pin configuration was tested in a total of 13 humeri: 4 in varus bending, 4 in valgus bending, and 5 in flexion bending. Displacement (mm), and load (N) data were sampled at 10 Hz during each test. Varus values were statistically lower in 2 LP group comparing to XP, 3 LP, LXP groups (p=0.01, p=0.02, p=0.012, consequently). Flexion load values statistically lower in 2 LP group comparing to XP, 3 LP, LXP groups (p=0.03, p=0.001, p=0,031, consequently). There was no difference between the groups in terms of valgus values (p>0.05). LXP technique is biomechanically similar to the traditional XP technique. In situations where orthopedic surgeons choose to use medial pins in addition to lateral pins such as distal humerus fractures with medial-sided defects.

Closed reduction with percutaneous Kirschner wire drill-and-pry for pediatric supracondylar humeral fractures with bony callus formation and delayed presentation

BackgroundSupracondylar humeral fractures are the most common type of pediatric elbow fractures, and are primarily treated using closed reduction and percutaneous pinning. For patients who are treated ≥14 days after the injury, after callus formation has occurred, closed reduction is usually not possible. The purpose of this study is to report the clinical outcomes of closed reduction with percutaneous Kirschner wire (K-wire) drill-and-pry for the delayed treatment of pediatric supracondylar humeral fractures with bony callus formation. MethodsWe retrospectively reviewed the data of 16 patients who underwent percutaneous K-wire drill-and-pry between November 2019 and August 2021 for the treatment of supracondylar humeral fractures with bony callus formation ≥14 days after the injury. Clinical outcomes were assessed using the Flynn criteria. The postoperative Baumann angle and pin configuration were evaluated using x-ray examinations. ResultsAll patients were followed up for 8–28 months (average, 16.63 months). The fractures healed in 4–6 weeks (average, 4.38 weeks). The operative time ranged from 10 to 124 min (average, 35.12 min). No iatrogenic vascular or nerve injury occurred. No patient developed cubitus varus. According to the Flynn criteria, 12 patients had excellent outcomes, 2 patients had good outcomes, 1 patient had a fair outcome and 1 patient had a poor outcome. ConclusionClosed reduction with percutaneous K-wire drill-and-pry is a mini invasive technique for supracondylar humeral fractures with bony callus formation in children. Most patients had a good clinical and cosmetic outcomes without scarring.

Does pin configuration matter in modified tension band wiring for transverse patellar fracture? A biomechanical study

BackgroundModified tension band wiring has been widely used for the treatment of transverse patellar fractures. The optimal position of a Kirschner wire (K-wire) in modified tension band wiring, however, has not yet been determined. The purpose of the present study was to evaluate biomechanically the effect of K-wire position in a modified tension band wiring technique. MethodsForty-two polyurethane foam patellae with a midway transverse fracture were assigned to six different fixation groups regarding different pin configurations in tension band wiring. The depth or sagittal position of the K-wire was divided into anterior and posterior. The coronal position of the K-wire was divided into central, medial and lateral. A specially designed set up simulated a knee with 60° flexion. All specimens were tested under axial traction. Loads at 2 mm and 4 mm fracture displacement and at the failure of the construct were recorded. ResultsAt 2 mm fracture displacement, anterolateral (AL) placement of K-wires revealed significantly less durability when compared with five other groups (P < 0.001). At 4 mm fracture displacement, the AL group also revealed inferior biomechanical strength when compared with other groups. Posteromedial (PM) K-wire placement group revealed more durability when compared with the posterolateral (PL) group (P < 0.05). At failure of the osteosynthesis, anteromedial (AM) and anterocentral (AC) groups revealed superior biomechanical strengths (P < 0.05). ConclusionsThe coronal and sagittal position of K-wire affects the biomechanical characteristics of modified tension band wiring. Anterolateral placement of K-wires revealed inferior strength to all other constructs in modified anterior tension band wiring.

Supracondylar Displaced Fracture of Elbow in Children Treated with Closed Reduction and Percutaneous K Wire Fixation

Objective: To compare the closed reduction and percutaneous K wire fixation method outcomes in the treatment of supracondylar displaced fracture of elbow in children. Study Design: Prospective study Place and Duration of Study: Department of Orthopaedics, Arif Memorial Teaching Hospital, Lahore from 2nd April 2021 to 31st September 2021. Methodology: One hundred and seventy children were included. Those children having supracondylar displaced fractures of elbow with a grade 3 were included in the study as participant. K wires of 1.5-2cm were used after closed reductions were satisfactorily achieved. Padded-Back slabs at posterior position of elbow were applied. At 2 weeks’ suture removal and pin configuration was also observed. Callus production was observed through radiological x ray images. Results: Majority of the children belonged to the age group of 6-10 years. There were 59.4% males while 40.58% were females. Within the total number of cases 55% were administered two lateral parallel K wires while 45% were administered cross K wire. Pin tract infection was formed in 2.5% of lateral K wire cases while it was observed in only 1.2 % of Cross wire cases. Most of the children got the fracture while playing a sport. The recovery phase was of 3.5 months while fracture joined in a mean value of 1 month. Conclusion: Lateral percutaneous pin technique for the management of supracondylar fracture of humerus bone is a more suitable method and offers same results without involvement of iatrogenic ulnar nerve injury. Keywords: Humerus, Ulnar nerve, Pin method, K-wire, Deformation

Response surface, neural network, and experimental approach to optimize process parameters and characterization of Al-Mg alloy by friction stir welding

In the present study, an interaction relationship has been developed by following a design matrix consisting of few combinations of tool rotational speed, traverse speed, and tool pin configurations to understand the evolution of structural and mechanical properties of friction stir welded (FSW) Al-Mg alloy. The welded Al-Mg alloy was characterized in terms of microstructure to analysis different zones of weld using optical and scanning electron microscope. The mechanical properties such as bulk &amp; micro hardness, and tensile strength were evaluated using Brinell, Vickers hardness tester, and tensometer respectively. The weld textures and grain size of the three different zones obtained using electron beam scattered diffraction (EBSD). Further, confirmation test was conducted to ensure the reliability. Results reveal that process parameters and tool pin profile influence the properties of the friction stir welded joints. The straight square pin configuration was the optimal structure for friction stir welding of Al-Mg alloy at a rotational speed of 1000 rpm and a welding speed of 40 mm/min, produced defect free weld with highest tensile strength of 136.25 MPa, bulk-hardness of 80.41 BHN, micro-hardness of 82 VHN in comparison with rest of the combinations considered in the investigation under same conditions. A fine recrystallized equiaxed grain with a partial fiber texture was evolved in the nugget zone. The measured experimental values agreed with the predicted data well.

Aerothermal analysis of pulsed jet impinging on a flat surface with different pin configurations

In this work, the effect of a pin as a secondary surface mounted on hydrothermal behavior of impinging jet over a flat plate investigated numerically and experimentally. The transient three-dimensional turbulent flow is simulated by the Renormalization Group (RNG) k − ɛ model. The injection air is pulsed by square waves. In a radial arrangement, several differently shaped pins (i.e., circular, elliptical, and square) with the same cross-sectional areas are compared. Three Reynolds numbers (10,000, 15,000 and 20,000) and four pin-to-injection point distances (r = 2D, r = 3D, r = 4D and r = 5D) are considered. Within the experimental range, the results indicated that the use of a pulsating jet in the frequency range of 50–100 Hz enhances the rate of heat transfer. The rate of heat transfer of the square pin is less than that of the smooth surface. Based on specific performance parameters, the elliptical pin is found to be a favorable alternative configuration to a circular pin. Also, the results showed that the appropriate position to mount the pin on a flat surface at a radial distance is three times the diameter of the jet (r = 3D) for elliptical and circular pins.

Outcome analysis of cross-pinning versus lateral pinning and various lateral pinning configuration in the treatment of displaced paediatric supracondylar humerus fracture

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Supracondylar humerus fracture accounts for 3% of all the paediatric fractures. Displaced fractures need usually closed but rarely open reduction and stabilization with k-wires by either cross or lateral pinning technique. Controversies prevail regarding the type of pinning which will reduce complications (such as ulnar nerve palsy and loss of reduction which will lead to cubitus varus deformity) and provides better functional and radiological outcome. The aim of study was to analyse outcomes of various pinning techniques in displaced supracondylar humerus fracture treatment.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods: &lt;/strong&gt;This was a prospective study done in SRIHER, Chennai (January 2019 to September 2020) included children with displaced supracondylar humerus fracture (modified Gartland type 2B,3). Preop, postop and intraop assessment were done with respect to incidence of ulnar nerve palsy, Baumann's angle, Flynn criteria till 14 weeks postop period. The results of cross pinning and lateral pinning group were statistically compared.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results: &lt;/strong&gt;There were totally 37 (male-25, female-12) patients. Mean age was 5.6. The mean change in Baumann’s angle of cross pin and lateral pin group at 14 weeks postop period comparing immediate postop period were 4.13 and 4.15 degrees, which was statistically insignificant using Mann Whitney test (p&amp;gt;0.05). Flynn criteria at 14 weeks postop period between two groups were also statistically insignificant. Difference in Baumann’s angle at 14 weeks postop period between divergent (2.82) and parallel (5.53) pin group was statistically significant using Mann Whitney test (0.01). There were no cases of ulnar nerve injury in both the groups.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Lateral pinning technique with the use of 3 divergent pins for the treatment of displaced supracondylar humerus fracture gives stability as good as cross pin configuration and also avoids the risk of ulnar nerve injury.&lt;/p&gt;

Preliminary conceptual design of fast neutron spectrum nuclear thermal rocket cores using monolithic uranium nitride fuel

This paper presents a few nuclear thermal rocket (NTR) reactor core preliminary conceptual designs based on the use of monolithic uranium nitride (UN) fuel plates or pins clad with tungsten (W), alloyed or unalloyed as needed. High-assay low-enriched uranium (HALEU) as well as high-enriched uranium (HEU) are considered. Nominal core thermal powers are between 300 and 1100 MW corresponding to thrusts between 66 kN and 240 kN. The estimated thrust-to-reactor-weight ratios (T/WRx) achievable with the HEU plate and pin configurations are between 3.8 and 10.9. The T/WRx achievable with the HALEU plate and pin configurations are lower, 1.9–4.0, than those achievable with HEU. It is noteworthy that even a relatively modest increase in fuel enrichment above the HALEU limit enables a significant increase in T/WRx. It must be emphasized that these results do not yet account for uncertainties and that the appropriateness of the assumed fuel thermal design limits for normal operation (i.e., peak centerline temperature of 3100 K) will need to be confirmed. Finally, just like for the other UN-based fuels currently considered for NTR applications (i.e., CERMET and CERCER), the proposed UN fuel systems need significant testing in prototypic conditions to confirm the appropriate performance for safe NTR applications. However, the monolithic fuel systems may have, overall, a higher technology readiness level (TRL), and, consequently, shorter fuel development and validation time may result.

A Modified Tension Band Fixation Technique for the Management of Patellar Fractures Using Crossed Pins and a Lateral Parapatellar Approach.

The use of the tension band technique for patellar fracture fixation has been associated with a loss of the rigidity of the construct after cyclic loading. Biomechanical studies have shown the biomechanical superiority of the crossed pin configuration relative to the traditional parallel one. Here, we describe a modified tension band technique that involves the use of crossed pins and a figure-of-eight passed as close to the bone as possible through a lateral parapatellar approach. The basic surgical technique and our case series are reviewed.

Analysis of the discharge plasma impedance of copper vapor laser

In the pursuit to analyze the impedance of copper vapor lasers (CVLs) in different conditions, a novel approach has been proposed in this paper. The underdamped behavior of the voltage waveform across the CVL is leveraged to compute the impedance of high-voltage discharge plasma in the laser. This methodology provides an accurate idea of the discharge plasma resistance and inductance as it is calculated on the basis of experimental voltage waveforms obtained from the laser system. The laser head inductance remains almost fixed and equivalent to ∼0.47 µH whereas the laser resistance changes between 34 Ω and 11 Ω depending on the discharge condition and its constituents. A critical evaluation of CVL impedance is done in all experimentally possible conditions, and a methodology has been proposed to maintain the CVL impedance, which results in the power stability of the laser in oscillator–amplifier configuration. The laser impedance variation w.r.t. time, pressure, operating voltage and electrode pin configuration has been investigated. The impact of the localized electric field at the electrode on the laser resistance has also been emphasized in this paper. A good concurrence exists between the calculated laser impedance and its experimental behavior.