Minimum Force Research Articles

Soft‐Actuated Cuff Electrodes with Minimal Contact for Bidirectional Peripheral Interfaces

AbstractNeural interfaces with embedded electrical functions, such as cuff electrodes, are essential for monitoring and stimulating peripheral nerves. Still, several challenges remain with cuff electrodes because sutured devices can damage the nerve by high pressure and the secured contact of electrodes with the nerve is hard to accomplish, which however is essential in maintaining electrical performance. Here, a sutureless soft‐actuated cuff electrodes (SACE) that can envelop the nerve conveniently by creating a bent shape controlled upon fluid injection, is introduced. Moreover, fluid injection protrudes part of the device where electrodes are formed, thereby achieving minimized, soft but secure contact between the electrodes and the nerve. In vivo results demonstrate the successful recording and stimulation of peripheral nerves over time up to 6 weeks. While securing contact with the nerve, the implanted electrodes can preserve the nerve intact with no reduction in blood flow, thereby indicating only minimal compressive force applied to the nerve. The SACE is expected to be a promising tool for recording and stimulation of peripheral nerves toward bidirectional neuroprostheses.

Compressive force and valgus torque are the predominant applied loads during the pivot shift exam: An in vitro study.

Despite the clinical utility of the pivot shift exam, the requisite applied forces and torques to elicit a pivot shift remain unclear. The purposes of this study are (1) to identify the greatest forces and torques applied to the knee during the pivot shift exam and (2) to evaluate if the applied loads differ among experienced surgeons. Three cadaveric hemipelvis-to-toe specimens (ages 53, 36 and 31 years; two males and one female) with no history of knee or hip injury were utilized. The experimental setup consisted of securing the hemipelvis to a mounting frame via an external fixator to simulate patient positioning during the clinical exam. The hemipelvis, femur, and tibia were spatially tracked by motion capture and the applied loads were measured using a 6-axis force-torque sensor. After sectioning the anterior cruciate ligament (ACL), three board-certified sports medicine surgeons then performed the pivot shift exam on each specimen utilizing their preferred technique. Forces (compression-distraction, anterior-posterior, and medial-lateral) and torques (varus-valgus, internal-external rotation, and flexion-extension) applied to the knee joint immediately preceding the reduction of the proximal lateral tibia during each pivot shift exam were calculated. Compression was the largest applied force averaging 95 N ± 15 N for all surgeons and knees, which was at least 4.5 times greater, on average, than the applied anterior and applied medial tibial forces (p < 0.0001). Valgus was the largest of the three applied torques, averaging 8.5 ± 2.1 Nm. Internal rotation torque was 3.7 times less, on average, than the applied valgus torque (p < 0.0001). Each surgeon applied compressive force. However, anterior force was more variable among surgeons, with one of the three surgeons applying minimal anterior force (p ≤ 0.024). The magnitude of applied torques was similar among examiners (n.s). Compressive force and valgus torque were the predominant applied loads during the pivot shift exam. A lower magnitude of internal rotation torque was also applied. The anterior force was not consistently applied among examiners. These data can better inform clinical, cadaveric, and computational studies utilizing the pivot shift exam to assess knee biomechanics and can be used to educate trainees in conducting this complex manoeuvre. An in vitro biomechanic study.

Optimized design of energy absorption of aluminum foam filled CFRP thin-walled square tube based on agent model

PurposeAluminum foam-filled thin-walled unit structures have received much attention for their excellent energy absorption properties. To improve the energy absorption effect of car energy absorption box under axial compression, this paper optimizes the fiber lay-up sequence, fiber angle and aluminum foam density of aluminum foam filled carbon fiber reinforced plastic (CFRP) thin-walled square tubes.Design/methodology/approachDesign of sample points required to construct the proxy model using design of experiments (DOE) method, and the data sample points of different models are obtained through Abaqus simulation and test. A double high-precision proxy model with the maximum specific energy absorption (SEA) and the minimum initial peak crash force (PCF) as the evaluation index is constructed based on the response surface function method. The NSGA-II multi-objective genetic algorithm was used to optimize the design parameters and obtain the optimal solution for the Pareto front, and the results were verified by using the multi-objective optimization toolbox in design-expert.FindingsThe results show that the optimal solution to the multi-objective optimization problem with the inclusion of the lay-up sequence is ρ = 0.5g/cm3 for a fiber lay-up angle varying in the range ±15–90° and an aluminum foam density varying in the range 0.2g/cm3-0.5g/cm3, with a lay-up method of [±87°/±16°/±15°/±89°]. The two optimization methods correspond to SEA and PCF errors of 2.109% and 4.1828%, respectively. The optimized SEA value is 18.2 J/g and the PCF value is 18,230 N. The optimized design reduces the peak impact force and increases the specific energy absorption, which improves the energy absorption effect of thin-walled energy-absorbing boxes for automobiles.Originality/valueIn this paper, the impact resistance of CFRP thin-walled square tubes filled with aluminum foam is optimized. Based on numerical simulations and experiments to obtain the sample point data for constructing the dual-agent model, we investigate the effect of filling with different densities of aluminum foam under the simultaneous change of fiber lay-up angle and order on its mechanical properties in this process, and carry out the multi-objective optimization design with NSGA-II algorithm.

Optimizing energy absorption and peak force in metal/glass fiber sandwich panels with trapezoidal cores

Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels’ energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications.

Clinical assessment of the potential use of a novel single-dose prefilled injection device for the administration of Acthar Gel in children: a narrative review.

Acthar® Gel (repository corticotropin injection; Mallinckrodt Pharmaceuticals, NJ, USA) is indicated for the treatment of myriad inflammatory disorders and is currently administered manually via a vial and syringe. The administration of Acthar via a single-dose prefilled injector (SelfJect™) is intended to simplify its subcutaneous (SC) delivery. The purpose of this review was to determine whether SelfJect is suitable for use in pediatric patients through a literature assessment of various factors, including skin depth, needle length and gauge, dosage, force required for injection, and potential harms. Infants and young children, who commonly have skin-to-muscle distances less than the minimum depth of SelfJect administration, may have risk of unintentional intramuscular (IM) injection; however, an inadvertent IM injection poses no additional risk to children because of the bioequivalence between SC and IM administration of Acthar. The needle gauge of SelfJect is acceptable for pediatric patients and aligns with the Centers for Disease Control and Prevention recommendations for SC injections. The dosage delivered by SelfJect is only appropriate for children over 2years of age. Although adolescents would likely be able to achieve the minimum force required to remove the protective cap and deliver a full dose of Acthar with SelfJect, an adult (18years of age and older) should administer SelfJect to pediatric patients. In addition to the commonly reported postmarketing adverse events (AEs) from Acthar administration (e.g., asthenic conditions, fluid retention, insomnia, headache and increased blood glucose), injection site-related AEs common to injection devices may occur with SelfJect use. The risk of needlestick injury from SelfJect is mitigated by a needle guard. In summary, this review of injection device considerations demonstrates that SelfJect is appropriate for use in the pediatric population.

Penentuan Penentuan Prioritas Lokasi Fasharkan TNI AL dengan Metode Fuzzy Analytical Hierarchy Process dan Geographic Information System

Based on the regulation of the Navy Chief of Staff No. Per Kasal/39/V/2009 dated May 26, 2009 concerning the development policy of the Navy towards minimum essential force, namely the preparation of the Navy's combat power is directed to achieve minimum essential force or abbreviated as MEF. According to the Chief of Staff of the Navy Number Kep/1771 / XII / 2013 concerning the Administrative Guidebook for the Standardization of TNI AL Bases (PUM-7.03) that a TNI AL Main Base (LANTAMAL) must have a class A Fasharkan, whose ability is to be able to carry out maintenance and repair up to the depot level for all types of KRI, both ship buildings, machinery, sewaco, electricity and ship armaments. There are many studies of location prioritization using the Analytical Hierarchy Process (AHP) method, but the results have uncertainty or decision uncertainty. So this research was conducted using the Fuzzy AHP method to overcome uncertainty or decision uncertainty. The Fuzzy AHP method is used for calculations to select alternatives. After the alternative is selected, then verification of location feasibility is carried out using the Geographic Information System (GIS) display. From the calculation using the FAHP method, Lantamal IX Ambon was selected as an alternative with a weight value of 0.251630342. While verifying the feasibility of the location using GIS, the Tawiri location was chosen as a more feasible land compared to other land options.

Demagnetization optimization of hybrid excitation eddy current damper under intensive impact load

The hybrid excitation eddy current damper is a novel principle damper characterized by high reliability, simple structure, and controllable magnetic field. Under intensive impact loads, hybrid excitation electromagnetic damping can induce demagnetization effects, resulting in significant fluctuations of the electromagnetic damping force at 6-8 ms. To mitigate this phenomenon, this study established a finite element model of the hybrid excitation damper using COMSOL and developed a control module based on a BP neural network in Simulink. Through co-simulation of COMSOL and Simulink, the difference between the maximum and minimum electromagnetic damping force at 6-8ms is reduced from 45 kN to 5 kN. This research provides valuable technical references for the optimization and practical application of eddy current dampers.

Muscle fatigue, pedalling technique and the slow component during cycling.

Above the first lactate threshold, the steady-state is delayed or prevented due to the slow component ( ). This phenomenon has been associated with muscle fatigue, but evidence for a causal relationship is equivocal. Moreover, little is known about the contribution of pedalling technique adjustments to during fatiguing cycling exercise. Eleven participants completed constant power trials at 10% above the second lactate threshold. Muscle fatigue was assessed, utilizing femoral nerve stimulation and instrumented pedals, while , quadriceps oxygenation, electromyography (EMG) and pedal force components were measured. Correlations between physiological and mechanical variables were estimated at group and individual levels. Group correlations revealed moderate values for with quadriceps twitch force (r=-0.51) and muscle oxygenation (r=-0.52), while weak correlations were observed for EMG amplitude (r=0.26) and EMG mean power frequency (r=-0.16), and with pedalling mechanical variables such as peak total downstroke force (r=-0.16), minimum total upstroke force (r=-0.16) and upstroke index of effectiveness (r=0.16). The findings here align with prior literature reporting significant correlations between the magnitude of muscle fatigue and that of , although there was large interindividual variability for all the reported correlations. Considering the heterogeneity in the data, it is difficult to determine therelative impact of pedalling technique adjustments on overall, but the present study opens the possibility that in some cases, increases in secondary to technical adjustments may be 'superimposed' on the underlying .

Visually Asymptomatic Leaf Loss in Xylella fastidiosa-Infected Blueberry Plants.

Xylella fastidiosa (Xf), a gram-negative bacterium, is a notorious, world-wide plant pathogen with an extended latent period that presents a challenge for early disease detection and control interventions. We used thermal imaging of tissue-cultured, experimentally Xf-infected blueberry plants to identify visually pre-symptomatic leaves and compared the minimum force required to dislodge symptomatic leaves from infected plants to leaves on uninfected (control) blueberry plants. For two different blueberry cultivars and one pathogenic isolate of X. fastidiosa, we found no statistical difference between the mean downward force for leaf dislodgement, regardless of symptom category, on Xf-infected blueberry plants. That force was about 50% to 30% of the mean force to remove leaves from uninfected blueberry plants depending on the cultivar. These results indicate that visually pre-symptomatic leaves may be just as readily lost under field conditions as visually symptomatic leaves, both of which are important for early disease detection. Second, some thermally symptomatic and visually symptomatic leaves appeared to self-prune (abscise) and this may be an unrecognized early symptom of Xf-caused disease in blueberries. Last, it is possible that the self-pruning of visually asymptomatic leaves may occur in other agriculturally and culturally important plants infected by X. fastidiosa, but this remains an unrecognized early disease symptom.

Effect of mediolateral leg perturbations on walking balance in people with chronic stroke: A randomized controlled trial.

Many people with chronic stroke (PwCS) exhibit deficits in step width modulation, an important strategy for walking balance. A single exposure to swing leg perturbations can temporarily strengthen this modulation. The objective of this parallel, double-blinded, randomized controlled trial was to investigate whether repeated perturbations cause sustained increases in step modulation (NCT02964039; funded by the VA). 54 PwCS at the Medical University of South Carolina were randomly assigned to one of three intervention groups: Control (n = 18), with minimal forces; Assistive (n = 18), pushing the swing leg toward a mechanically appropriate location; Perturbing (n = 18), pushing the swing leg away from a mechanically appropriate location. All intervention groups included 24 training sessions over 12-weeks with up to 30-minutes of treadmill walking while interfaced with a novel force-field and a 12-week follow-up period, with five interspersed assessment sessions. Our primary outcome measure was paretic step width modulation, the partial correlation between step width and pelvis displacement (ρSW). Secondarily, we quantified swing and stance leg contributions to step modulation, clinical assessments of walking balance and confidence, and real-world falls. Outcomes were analyzed for participants who completed all assessment sessions (n = 44). Only the Perturbing group exhibited significant increases in paretic ρSW, which were present after 4-weeks of training and sustained through follow-up (t = 2.42-3.17). These changes were due to improved control of paretic swing leg positioning. However, perturbation-induced changes in step modulation were not always significantly greater than those in the Control group, and clinical assessments were similar across intervention groups. Participants in the Perturbing group experienced a lower fall rate than those in the Control group (incidence rate ratio = 0.53), although our small sample size warrants caution. The present results indicate that perturbations can cause sustained modifications of targeted biomechanical characteristics of post-stroke gait, although such changes alone may be insufficient to change more complex clinical assessments.

Analysis and Design of Electrical Transmission Towers with Various Sections and Bracing Configurations

Abstract: This study focuses on the analysis and design of a 400kV electrical transmission tower with a height of 50 meters. The tower was modeled in STAAD.PRO using three distinct steel sections Angle, Tube, and Channel combined with various bracing configurations, including X, K, and D-bracings. The main objective of this study is to determine the most efficient and economical configuration for the design of Transmission tower. The tower is analyzed for Dead load, Live load and wind load as per the codes. The study concludes that transmission towers with angled sections and X-bracing exhibit moderate displacement, minimal reaction forces, and reduced structural weight, making them a preferred design choice. Manual calculations were performed to design the connections and footing, ensuring structural integrity. The results confirm that the tower's connection design is safe and reliable

Experimental and numerical study on mounting force and withdrawal strength of self-threaded dowels in particleboard

Traditional and alternative joining techniques have been used for many years at the connection points of structural bearing systems. Especially, glued doweled and screwed type mechanical connections are widely used in wooden structures and furniture constructions. Although there are many studies related to the strength of dowel and screw joints, limited papers describe the practical use of self-threaded dowels (STDs) in the joints. In this study, thread geometry effect of the STDs in particleboard (PB) was investigated by determining the mounting force and withdrawal strength values. For this purpose, STDs including three different thread width (0,2 - 0,3 - 0,4 mm) and two different thread length (1 - 2 mm) were designed, produced and tested under static compressive and tensile forces. All STDs were produced with polylactic acid (PLA) by using Layer Plastic Deposition (LPD) method in 3D printing technology. Uniaxial compression tests were performed in order to determine the minimum mounting force while the tension tests were performed for determining the maximum withdrawal force required to put the STDs into the hole and pull out them, respectively. Numerical analysis (FEM) were used to analyze the contact pressures and stresses of the STD joints. Abaqus v6.13-1 software was utilized for the numerical analyses. In addition, multiple regression analysis was carried out to predict the mounting force and withdrawal strength of the STDs. Results showed that the predictive expressions developed provided reasonable estimates for mounting force and withdrawal strength of STDs. According to the statistical analyses; thread width, thread length and their interaction have significantly affected both mounting force and withdrawal strength of STDs. At the end of the experimental and numerical tests, STDs with 0,2 mm width and 2 mm length threads gave the lowest mounting force values, stresses and contact forces. However, the highest withdrawal strength values were obtained from the STDs with 0,3 mm width and 1 mm length threads. According to the results of the study, the optimum STD was the one with 0,3 mm thread width and 2 mm thread length. In conclusion, the STDs can be utilized as an alternative fastener to the conventional glued dowel type joints in PB. However, corner joints constructed of different kinds of wood-based composites and connected with the STDs should be investigated in the future studies.

Injectable PLGA Microscaffolds with Laser-Induced Enhanced Microporosity for Nucleus Pulposus Cell Delivery.

Intervertebral disc (IVD) degeneration is a leading cause of lower back pain (LBP). Current treatments primarily address symptoms without halting the degenerative process. Cell transplantation offers a promising approach for early-stage IVD degeneration, but challenges such as cell viability, retention, and harsh host environments limit its efficacy. This study aimed to compare the injectability and biocompatibility of human nucleus pulposus cells (hNPC) attached to two types of microscaffolds designed for minimally invasive delivery to IVD. Microscaffolds are developed from poly(lactic-co-glycolic acid) (PLGA) using electrospinning and femtosecond laser structuration. These microscaffolds are tested for their physical properties, injectability, and biocompatibility. This study evaluates cell adhesion, proliferation, and survival in vitro and ex vivo within a hydrogel-based nucleus pulposus model. The microscaffolds demonstrate enhanced surface architecture, facilitating cell adhesion and proliferation. Laser structuration improved porosity, supporting cell attachment and extracellular matrix deposition. Injectability tests show that microscaffolds can be delivered through small-gauge needles with minimal force, maintaining high cell viability. The findings suggest that laser-structured PLGA microscaffolds are viable for minimally invasive cell delivery. These microscaffolds enhance cell viability and retention, offering potential improvements in the therapeutic efficiency of cell-based treatments for discogenic LBP.

Nanofluid minimum quantity lubrication assisted grinding force model considering anisotropy of SiCf/SiC ceramic matrix composites

SiCf/SiC ceramic matrix composites with excellent thermal stability, light weight and oxidation resistance have become key components in advanced aircraft engines. Nanofluid minimal quantity lubrication (NMQL) exhibits significant potential in enhancing heat transfer and lubrication efficiency during the grinding process. The technological challenge lies in thoroughly investigating the theoretical variation rule of grinding force, assisted by nanofluid minimal quantity lubrication, and subsequently achieving low-damage machining of SiCf/SiC composites. In this study, a prediction model for the grinding force during NMQL-assisted grinding was established, integrating diverse lubrication methods, grinding wheel geometric parameters, wear degree, process parameters, the anisotropy and damage degree of SiCf/SiC composites. The model was subsequently experimentally validated through grinding tests conducted on SiCf/SiC composites under various conditions, including dry grinding (DG), flood grinding (FG), minimum quantity lubrication (MQL), and carbon nanotube nanofluids (NMQL-CNTs), across multiple grinding depths. The present investigation’s grinding force forecasting model is evidenced to possess high accuracy of precision, showcasing mean deviations of 6.64 % and 11.97 % in the perpendicular (Fn) and tangential (Ft) grinding force components, respectively. Additionally, employing NMQL-CNTs facilitates the achievement of minimal grinding force and surface finish quality. At depths of 0.4 mm and 0.6 mm during grinding, the mean Fn magnitudes under the NMQL-CNTs lubrication approach underwent a decrease of 66.7 % and 74.5 %, respectively, in contrast, the mean Ft magnitudes experienced a reduction of 55 % and 67.2 %, correspondingly, in comparison to the DG lubrication technique. Notwithstanding the consistency in the material’s brittle removal mechanism across varying lubrication strategies, the NMQL-CNTs approach effectively alleviates fiber abrasion. Concisely, the research presented herein provides foundational theoretical insights and practical technological assistance for the achievement of low damage SiCf/SiC composite processing.

Kinematic and aerodynamic analysis of a Microraptor-inspired foldable wing mechanism

Bio-inspired mechanisms have opened new avenues of research to understand the flying capabilities of birds. While extensive studies have explored the aerodynamics and kinematics of bird flapping motions, limited attention has been given to the folding motion. This paper introduces a foldable wing mechanism inspired by avian anatomy, specifically drawing inspiration from Microraptor aerodynamics. Employing the screw theory approach, we analyze the kinematics of the mechanism and conduct parametric calculations. By segmenting the mechanism and integrating the solutions, we develop an algorithm that demonstrates favorable power transmission, enabling the wing to remain extended with minimal actuation forces. We further employ position analysis to investigate the system’s functionality analytically. To optimize the mechanism, we utilize the gradient descent method. We validate the achieved momentum and velocities through an illustrative example by solving individual four-bar segments and transmitting the outputs to adjacent segments. The study utilizes detailed 3D modeling techniques employing SolidWorks software to accurately represent the wing designs. The results obtained provide valuable insights into the aerodynamic behavior of Microraptor, by comparing the coefficients of lift and drag in graphical form and contribute to the advancement of micro-aerial vehicle design.

Frictional Axial Resistance of Clamped Split Pocket Mechanism Steel Structural Joint: An Experimental Study

The Clamped Split Pocket Mechanism (CSPM) prefabricated joint system was developed for a single-story steel instant house, designed to be compact and rapidly constructed without modifying the end of the beam and column element member. The CSPM bolted joint system was proposed as an optimal solution for post-disaster housing, especially after earthquakes. Despite its potential, the frictional tensile resistance behavior of the CSPM bolted joint system has not been previously studied, necessitating experimental investigation. This study examined the frictional tensile resistance behavior of the CSPM joint system by monitoring the effective friction coefficient under axial tension force. The experiments considered both the strong and weak axes of the joint and utilized two configuration types of specimens (L and T) with varying bolt pretensions of 2.5, 5, 7.5, and 10 kN. Results indicated that the effective friction coefficient of the CSPM bolted joint system ranged from 0.19 to 0.26, correlated to bolt pretension. Increased bolt pretension resulted in larger surface deformation of the split pocket, triggering a not uniform frictional tensile resistance across the steel surfaces of the split pocket joint. From this study, the achieved effective friction coefficients could guide the design of minimum pretension forces for clamps in prefabricated steel instant houses. Doi: 10.28991/CEJ-2024-010-09-07 Full Text: PDF

Orientation optimization of the Halbach PMG for the levitation and guidance performance of the HTS maglev system

High-temperature superconducting maglev technology has great application potential in rail transit applications due to its advantages such as passive stable levitation and green environmental protection. As one of the key components of the HTS maglev system, the Halbach-type permanent magnet guideway (PMG) enhances the magnetic field on one side of the guideway and weakens that on the other side. Optimizing the PMG, including the geometry and magnetic properties of the magnet, is an effective method to improve the levitation and guidance performance of the system. In addition, since NdFeB permanent magnets are expensive, optimizing the design of the PMG for the HTS maglev system is also an important work to reduce the application cost. In this paper, the Nelder–Mead Simplex method (NMS) in the optimization solver in COMSOL software is used to optimize the geometric parameters of the Halbach PMG according to the different objective requirements of the HTS maglev system. The optimization objectives include the maximum levitation force and guidance force under the constraint of the maximum cross-sectional area of the PMG, as well as the minimum cross-sectional area of the PMG with a minimum levitation force constraint. The results indicate that the NMS method is effective. By comparing four PMGs during the optimization process, it is found that this method can fully improve the utilization of the magnetic field by changing the geometric parameters of the Halbach PMG. This study can provide a valuable reference for the optimal design of the PMG for HTS maglev systems in the future.

Evaluation of a Slim Modiolar Electrode Array: A Temporal Bone Study.

Evaluation of the Slim Modiolar (SM) electrode in temporal bones (TB) will elucidate the electrode's insertion outcomes. The SM electrode was designed for atraumatic insertion into the scala tympani, for ideal perimodiolar positioning and with a smaller caliber to minimize interference with cochlear biological processes. The SM electrode was inserted into TBs via a cochleostomy. First, the axial force of insertion was measured. Next, TBs were inserted under fluoroscopy to study insertion dynamics, followed by histologic evaluation of electrode placement and cochlear trauma. A subset of TBs were inserted with the Contour Advance (CA) electrode for comparison. Sixteen of 22 insertions performed to measure the axial force of insertion had flat or near zero insertion force profiles. Six insertions had increased insertion forces, which were attributed to improper sheath depth before electrode insertion. Under real-time fluoroscopy, 23 of 25 TBs had uneventful insertion and good perimodiolar placement. There was 1 scala vestibuli insertion due to suboptimal cochleostomy position and 1 tip roll over related to premature electrode deployment. When compared with the CA electrode, 14 of 15 insertions with the SM electrode resulted in a more perimodiolar electrode position. No evidence of trauma was found in histologic evaluation of the 24 TBs with scala tympani insertions. TB evaluation revealed that the SM electrode exerts minimal insertion forces on cochlear structures, produces no histologic evidence of trauma, and reliably assumes the perimodiolar position. Nonstandard cochleostomy location, improper sheath insertion depth, or premature deployment of the electrode may lead to suboptimal outcomes.

Pull-Off Forces on Implant-Supported Single Restorations by Sticky Food: An InVitro Study.

To investigate the pull-off forces on implant-supported restorations caused by sticky food, to understand how much retention force cemented restorations must have to withstand chewing forces without unintentional retention loss. The influence of food type, restoration design, and surface treatment were investigated. Monolithic implant-supported CAD/CAM zirconia crowns were fabricated and divided into groups according to their design: no (NC), flat (FC) and high cusps (HC) and subdivided according to surface roughness: rough (r) and smooth (s) (n = 10/group). NC represented the control group. The crowns were fixed in a universal testing machine opposite to each other. Four sticky foods (caramel, fruit jelly, candy strips and licorice) and a resin crown remover were tested. These were heated (36.4°C), placed between the crowns and compressed, then tensile strength tests were performed. The maximum pull-off force was recorded (Newton [N]). Statistical analysis was performed using 3-way ANOVA. The highest mean pull-off force among food samples was with caramel_HC_r (12.09 ± 1.26 N), whereas the lowest was with licorice_FC_s (3.21 ± 0.15 N). For the resin crown remover, a mean pull-off force of 55.41 ± 3.87 N was measured in the HC_r group. Both food type and crown design showed a significant influence on pull-off force (p < 0.001), whereas no significant effect was reported with different surface roughnesses (p = 0.344). This study reported pull-off forces of up to 20 N between all-ceramic restorations caused by sticky food. The clinical implication of these findings is that a cemented implant-restoration must have a minimum retention force of 20 N to withstand unintentional displacement during function.

On Spatial Systems of Bars Spherically Jointed at Their Ends and Having One Common End

In this paper we consider a system of linear bars, spherically jointed at their ends. For each bar one end is linked to the origin. We discuss the equations from which one obtains the deviation of the origin, and some possible optimizations concerning the minimum displacement of the origin and the minimum force in one bar, which are the main goals of the paper. The optimization is performed considering that for two bars one end is unknown; that is, the angles between the bars and the axes are unknown. It is proved that it is difficult to obtain an analytical solution in the general case, and the problem can be discussed only by numerical methods. A numerical case is also studied and some comments concerning the results are given.