Method Of Force Application Research Articles

Applicability study of mechanical multi-pipe connections for DEMO breeding blanket maintenance concept

Maintenance of DEMO breeding blanket includes the removal and replacement of plasma facing components, for example the breeding blankets (BB). For access, multiple coolant pipes need to be removed. As an option to reduce downtime and increase maintenance speed, a so-called mechanical multi-pipe connection (MPC) concept is developed to allow removal of multiple pipes at the same time using remotely operated mechanical connections. MPC is one promising candidate to allow fast remotely controlled opening and closing of multiple pipe connections by using flanges and bolts.Some major challenges for the application of MPC are highly constrained space on top of the BBs, accessibility for appropriate tools and homogenous distribution of sealing forces on the gaskets. Numerous studies on arrangement and force application methods were performed to identify suitable concepts – of which a compact flange design using direct bolted connection is favourable. Finite Element Analyses on the shape and geometry optimization of the MPC led to analytically verified solutions. Furthermore, material selection and behaviour under radiation, vacuum, and thermal cycling at high temperature conditions requires advancement of available material treatment solutions in terms of things such as coated surfaces of threads and contact areas on flanges to avoid diffusion bonding.

Failure rates and factors associated with infrazygomatic crestal orthodontic implants - A prospective study.

Infrazygomatic crestal (IZC) implants have gained increased popularity over the past few years. Hardly any studies have been done to assess the rate and reasons for failure of IZCs. This prospective study was planned and designed with the primary objective of assessing the rate of failure of bone-screws (BS) placed in the infrazygomatic crest. In continuation, the secondary objective was to assess the factors that were associated with the failure. The study was carried out by taking a detailed case history, (age, gender, vertical skeletal pattern, medical history), photographic records, radiographs, and clinical examination of a total of 32 randomly selected. patients of south indian origin who required infrazygomatic implants bilaterally as the choice of anchorage conservation to retract their incisors. All selected subjects were required to take a PA Cephalogram after the implant placement. The age of the patients ranged from 18 to 33 with an average age of 25 years. The patient log was maintained which included the treatment mechanics, status of oral hygiene, stability of implants, time of loading of the implant, presence of inflammation and time of failure of implant. The angulation of implant was measured on a digital PA cephalogram using Nemoceph software. These parameters were examined to evaluate independent and dependent variables using the Chi-Square test and Fischer's exact test. A failure rate 28.1% for IZC placed in the infrazygomatic crest region was observed. Patients with a high mandibular plane angle, poor oral hygiene, immediately loaded implant, peri-implantitis, and severe clinical mobility showed higher failure rates. Variables such as age, gender, sagittal skeletal pattern, length of the implant, type of movement, occluso-gingival position, method of force application, and angle of placement were not significantly associated with implant failure. Oral hygiene and peri-screw inflammation must be controlled to minimize the failure of bone screws placed in the infrazygomatic crest region. Loading of the implant should be done after a latent period of two weeks. A higher failure rate was observed in patients with vertical growth pattern.

Effects of actuation mode on plasma-induced spanwise flow oscillations

Two different plasma actuation strategies for producing near-wall flow oscillations, namely the burst-modulation and beat-frequency mode, are characterized with planar particle image velocimetry in quiescent air. Both concepts are anticipated to work as non-mechanical surrogates of oscillating walls aimed at turbulent flow drag reduction, with the added benefit of no moving parts, as the fluid is purely manipulated by plasma-generated body forces. The current work builds upon established flow-control and proof-of-concept demonstrators, as such, delivering an in-depth characterization of cause and impact of the plasma-induced flow oscillations. Various operational parameter combinations (oscillation frequency, duty cycle and input body force) are investigated. A universal performance diagram that is valid for plasma-based oscillations, independent of the actuation concept is derived. Results show that selected combinations of body force application methods suffice to reproduce oscillating wall dynamics from experimental data. Accordingly, the outcomes of this work can be exploited to create enhanced actuation models for numerical simulations of plasma-induced flow oscillations, by considering the body force as a function of the oscillation phase. Furthermore, as an advantage over physically displaced walls, the exerted body force appears not to be hampered by resonances and therefore remains constant independent of the oscillation frequency. Hence, the effects of individual parameter changes on the plasma actuator performance and fluid response as well as strategies to avoid undesired effects can be determined.

Triggering Forces at the Nanoscale: Technologies for Single-Chain Mechanical Activation and Manipulation.

Over the past decades, polymer mechanochemistry has focused on the development and application of advanced force application methods to better understand the mechanochemical response of mechanophores. In this regard, techniques such as ultrasonication and single-molecule force spectroscopy (SMFS) are used to activate and detect up to thousands of chemical events within a polymer single chain, allowing the researchers to probe the mechanochemical reactivity of these stress-responsive motifs. Here, the most recent contributions of the single-molecule force spectroscopy technique to this field are presented, putting emphasis on the fundamental parameters of the technique for triggering specific force responses and on the description of force-extension curves measured for single- and multi-mechanophore polymers. Moreover, new contributions of microscopy-based techniques in the field of polymer mechanochemistry, as well as the potential application of single-chain nanoparticles as mechanoresponsive materials, are highlighted.

Preparation and characterization of nanofibrillated cellulose from waste sugarcane bagasse by mechanical force

The effect of different mechanical force application methods was investigated relative to the structure and properties of nanofibrillated cellulose (NFC) from sugarcane bagasse. The NFC was prepared by grinding, high pressure homogenization, and ultrasonication with chemical pretreatment. Fiber morphology, crystalline, chemical structures, and tensile property were analyzed to reveal the mechanisms of NFC production behind different mechanical treatments. The results showed that compared with grinding treatment, high pressure homogenization and ultrasonic treatment can obviously increase the aspect ratio and size uniformity of NFC. Ultrasonic treatment gave the best results. The combination of grinding, high pressure homogenization, and ultrasonic treatment resulted in NFC with the average diameter of 23.18 nm. With the shearing action of grinding, high pressure homogenization, and ultrasonic treatment, the mechanical properties, crystallinity and thermal stability of NFC were gradually enhanced. This results demonstrated that a very low-value agricultural waste product can be easily converted to a high performance nanocomposite with tensile strength of 153.6 MPa and strain at break of 8.83%.

Orthodontically induced root resorption: An updated review

Background/Aim: Root resorption is one of the most common consequences of orthodontic treatment. However, its mechanism, etiology factors, diagnostic methods and the possibility of root repair remain controversial topics. The aim of this paper is to provide an updated review of the current literature concerning the orthodontically induced root resorption. Material and Methods: A literature search was performed using Google Scholar, PubMed and Scopus search engines covering the period January 1930 until June 2019 corresponding to articles investigating the mechanism, etiology, methods of interpretation of root resorption and the stages of root repair. Results: The mechanism of orthodontically induced root resorption involves an interaction between several molecular signaling pathways, which result in the resorption of both cementum and dentin by odontoclasts/cementoclasts. Root resorption can be the result of both treatment and patient-related factors. The main risk factors include prolonged orthodontic treatments, heavy forces, specific tooth movements, method of force application, systemic/genetic factors and aberrant root morphology. Nevertheless, root resorption is repaired to some extend by cellular cementum. Conclusions: Orthodontically root resorption is an unavoidable complication mainly due to its multifactorial etiology. However, its severity can be minimized with careful planning and radiographic monitoring.

Stability of miniplates and miniscrews used for orthodontic anchorage: experience with 492 temporary anchorage devices

The aim of this retrospective study was to evaluate systematically the potential factors that influence failure rates of temporary anchorage devices (TADs) used for orthodontic anchorage. Data on 492 TADs (miniplates, pre-drilling miniscrews, and self-drilling miniscrews) in 194 patients were collected. The factors related to TAD failure were evaluated using univariate analysis and multivariate forward stepwise logistic regression analysis. There were no significant differences in failure rates among the TADs for the following variables: gender, type of malocclusion, facial divergency, implantation site (buccal, lingual, or crestal/midpalatal), location (anterior or posterior), method of force application (power chain or Ni-Ti coil spring), arch (upper or lower), type of soft tissue (attached gingiva or removable mucosa), and most of the cephalometric measurements that reflect dento-cranio-facial characteristics. An increased failure rate was noted for the self-drilling miniscrew type of TAD, TADs used for tooth uprighting, those inserted on bone with lower density, those associated with local inflammation of the surrounding soft tissue, those loaded within 3 weeks after insertion, and those placed in patients with greater mandibular retrusion. Failure rates of the self-drilling miniscrews installed by an oral surgeon and by an orthodontist did not differ significantly. Inflammation of soft tissue surrounding a TAD and early loading within 3 weeks after insertion were the most significant factors predicting TAD failure. Both orthodontists and oral surgeons who install orthodontic TADs must undergo sufficient training to achieve clinical excellence.

On the incubation stage of fracture and structural transformations in continuous media under pulse energy injection

Experiments on fracture and structural transformations caused in solid and fluid media as well as in conductors and dielectrics by an intensive pulse action of the ambient medium or by directed energy fluxes reveal several effects showing that dynamic fracture (breakdown) of materials substantially differs from similar processes under slow quasistatic actions. For example, one of the main problems in modeling the dynamic strength properties of materials is related to the dependence of the limit characteristics on the loading history and methods. The dependence on the method of force application manifests itself as a large (hundreds to thousands percent) variation in the limit variables caused by variations in the action duration, amplitude, increase rate of the external action, and several other factors. While the critical value in statics can be treated as a material constant (or a quantity varying relatively slowly, at most, within several dozens percent), the experimentally determined values of the critical characteristics in dynamics are characterized by very strong instability and can differ by orders of magnitude. As a result, the dynamic behavior of a system whose description is based on these characteristics turns out to be unpredictable.

Manual Application of Controlled Forces to Thoracic and Lumbar Spine With a Device: Rated Comfort for the Receiver's Back and the Applier's Hands

Purpose High volumes of manual therapy work can lead to overuse hand and wrist injuries. This study evaluated hand and back comfort in asymptomatic volunteers during spinal mobilization carried out with an instrumented manual therapy tool. Methods This crossover design study examined 36 asymptomatic physiotherapy students that were tested in pairs. One participant assumed the role of the simulated therapist and the other the simulated patient, before reversing roles. Posteroanterior mobilization conditions formed by using 2 spinal segments (thoracic/lumbar), 2 force application methods (hands/device), and 3 grades of mobilization were applied in a random order. After each combination, both participants in each pair rated hand or back comfort, respectively, on a 100-mm visual analogue scale. Data were analyzed by analysis of variance. Results Rated back comfort was greater for hands than for the device and decreased with greater applied force. When the original hard rubber device tip was changed to one of soft molded rubber, both back and hand comfort improved significantly. Although tool mobilization was still rated as significantly less comfortable than mobilization with hands only, this difference was approximately half the discomfort experienced as the grade of mobilization increased from grade I to grade III. For hand comfort when using the softer device tip, the method of force application was no longer a significant determinant of comfort. Conclusions The mobilizing tool with a molded rubber tip was acceptably comfortable in use with asymptomatic backs and hands. Further research is indicated in manual therapy settings with therapists who have experienced hand pain.

Factors affecting the clinical success of screw implants used as orthodontic anchorage

The purposes of this study were to examine the success rates and find factors affecting the clinical success of screw implants used as orthodontic anchorage. Eighty-seven consecutive patients (35 male, 52 female; mean age, 15.5 years) with a total of 227 screw implants of 4 types were examined. Success rates during a 15-month period of force application were determined according to 18 clinical variables. The overall success rate was 91.6%. The clinical variables of screw-implant factors (type, diameter, and length), local host factors (occlusogingival positioning), and management factors (angle of placement, onset and method of force application, ligature wire extension, exposure of screw head, and oral hygiene) did not show any statistical differences in success rates. General host factors (age, sex) had no statistical significance. Mobility, jaw (maxilla or mandible), and side of placement (right or left), and inflammation showed significant differences in success rates. Mobility, the right side of the jaw, and the mandible were the relative risk factors in the logistic regression analysis when excluding mobility, inflammation around the screw implants was added to the risk factors. To minimize the failure of screw implants, inflammation around the implant must be controlled, especially for screws placed in the right side of the mandible.

Thin-foil magnetic force system for high-numerical-aperture microscopy.

Forces play a key role in a wide range of biological phenomena from single-protein conformational dynamics to transcription and cell division, to name a few. The majority of existing microbiological force application methods can be divided into two categories: those that can apply relatively high forces through the use of a physical connection to a probe and those that apply smaller forces with a detached probe. Existing magnetic manipulators utilizing high fields and high field gradients have been able to reduce this gap in maximum applicable force, but the size of such devices has limited their use in applications where high force and high-numerical-aperture (NA) microscopy must be combined. We have developed a magnetic manipulation system that is capable of applying forces in excess of 700 pN on a 1 mum paramagnetic particle and 13 nN on a 4.5 mum paramagnetic particle, forces over the full 4pi sr, and a bandwidth in excess of 3 kHz while remaining compatible with a commercially available high-NA microscope objective. Our system design separates the pole tips from the flux coils so that the magnetic-field geometry at the sample is determined by removable thin-foil pole plates, allowing easy change from experiment to experiment. In addition, we have combined the magnetic manipulator with a feedback-enhanced, high-resolution (2.4 nm), high-bandwidth (10 kHz), long-range (100 mum xyz range) laser tracking system. We demonstrate the usefulness of this system in a study of the role of forces in higher-order chromosome structure and function.

The Influence of Varying Precompaction and Main Compaction Profile Parameters on the Mechanical Strength of Compacts

The purpose of this work was to investigate how altering the method of force application could be beneficial to tablet production in order to increase tablet strength and eliminate or minimize the incidence of capping and lamination. An integrated compaction research system (i.e., compaction simulator) was used throughout this study. Compaction profiles containing a single compaction event and a double (pre- and main) compaction event were created. The ratio and magnitude of the pre- and main compaction pressures were varied and the time interval between the pre- and main compaction events was altered to determine the effects on the crushing strengths and capping tendency of the final compacts. In all cases, for a given pressure, the double compaction event produced stronger tablets than the single compaction event. When the ratio and magnitude of the pre- and main compaction pressures were varied, the results differed depending on the material undergoing compaction. Dicalcium phosphate/microcrystalline cellulose and pregelatinized starch tablets had no significant difference in crushing strength values regardless of whether the precompaction pressure was less than or greater than the main compaction pressure. However, both direct compression (DC) acetaminophen and DC ibuprofen were found to have increased crushing strengths and decreased capping/lamination when the precompaction pressure was less than the main compaction pressure. When the time interval between the pre- and main compaction events was varied from 30 to 500 msec, no significant difference in the crushing strength or capping/lamination tendency was observed. It was concluded that the effect of altering the ratio and magnitude of the pre- and main compaction pressures varied from one material to another, suggesting that the profiles should be tailored individually for the specific material undergoing compaction.

Replication and Classification of Small Size Lithic Debit Age

A summary of attributes of small lithic flakes produced in making bifaces by several force application methods is presented, based on experimental flint knapping. The usefullness of these attributes in classifying manufacturing techniques is discussed. It is shown that attributes commonly measured are not always sufficient to identify force application techniques. It is especially difficult to identify force application methods on archeological sites due to sampling problems and the possibility of a mixture of techniques.