Tying Method Research Articles

Novel Tie Method for the Fixation of a Brain Infusion Cannula in a Murine Model

Although brain infusion cannula is a good method to deliver compounds directly into the brain, fixation of the brain infusion cannula is essential for successful delivery. Dental cements and adhesive gel are the commonly used materials for fixation of the infusion cannula. However, these materials take time to harden and occasionally, fixation may fail. Therefore, we developed a novel method to fix the brain infusion cannula. Brain infusion cannulas were implanted into seven Wistar rats using the novel tie method. One, three, and seven days after the surgery, displacement of the brain infusion cannula and cerebrospinal fluid (CSF) leakage were evaluated in all the rats. None of the animals showed displacement of the brain infusion cannula or leakage of CSF at any point of time. In this study, we showed the successful results of the novel tie method for fixation of the brain infusion cannula, which needs no additional materials. It only requires a thread which is used for skin sutures.

Finite element analysis of reinforced concrete deep beam with large opening

BackgroundA series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening.ResultsThe service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit.ConclusionIt is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

Modified Strut and Tie Method and Truss Reinforcement for Shear Strengthening of Reinforced Concrete Deep Beams

The aim of this study was to evaluate and test the limitations of the Indian Standard code 456-2000 related to deep beams, given that the code does not have any provisions regarding the use of the strut and tie method (STM)of design. This study v

A Combined Tie-Fastening Method for the Reusable Surgical Gown with Two Neck Tie Belts to Improve Wearing Comfort.

The reusable surgical gowns made of slippery materials have the tendency to slip down as they are being worn. The rear neck tie(s) can sometimes loosen, and this causes the surgical gown to slip down somewhat, making the surgical staff members feel uncomfortable. If the gowns have two rear neck ties with a tendency of loosening and allowing the gowns to slip down, the surgical staff members feel more uncomfortable when there is only one tie loosening but the other tie is tethering. To fasten the neck ties of the surgical gown with two neck tie belts, we propose a simplified method of fastening the two sets of tie belts together as one tie, instead of fastening them separately. The object of this study is to evaluate this combined tying method for its ability to secure the gown and its wearing comfort. We enrolled five volunteers to evaluate the tie loosening condition of the reusable surgical gowns with two sets of rear neck tie belts after a series of upper limb motion exercises while wearing and not wearing the X-ray protective apron beneath the gown. The amount of uppermost rear neck cloth edge separation was recorded before and after the exercise. We also evaluated the wearing comfort of five enrolled operating surgeons for comparing the original and this modified tying method while wearing and not wearing the X-ray protective apron. In the results, we found that combined tying tends to have significantly more rear gown separation (0.94 cm) than separate tying (0.27 cm) after vigorous upper extremities exercise. However, during the actual performance of the surgeries, the rear neck tie(s) loosening and wearing discomfort of the combined tying method was significantly less than using the separate tying method (loosening: 0% vs. 30%) (discomfort: 0% vs. 35%) while the X-ray protective apron was not worn. For reusable surgical gowns that have two rear neck ties, we suggest the two sets of rear neck ties could be fastened together as one combined tie in routine surgical practice. With this, tying could be performed easier and faster, and wearing comfort could be improved.

Combining In-Tip Reaction and Infrared Thermal Imaging for Fast and Portable Enthalpimetric Analysis.

In this work, the in-tip thermal infrared enthalpimetry (in-tip TIE) method is proposed for fast enthalpimetric analysis. In this method, the reactions inside the tips of a multichannel pipette were combined with temperature monitoring by an infrared camera. The filter paper was used inside the tips to retain reagents as solutions (wetted paper mode) or as solids (dried paper mode) to perform neutralization, redox, or precipitation reactions. The dried reagents inside the tips were obtained by oven drying a solution retained in the filter paper. The determination of the total acidity of the vinegar, ascorbic acid in vitamin C tablets, and chloride in soy sauces and saline inhalation solutions was performed as examples of the application of the proposed method. The agreement with reference methods ranged from 98 to 107%. The use of reagents dried inside the tip was feasible, leading to a simple aspiration of sample solution within the 12 tips of the pipette to perform a rapid analysis (1 min). Therefore, up to 720 measurements in 1 h were feasible for in-tip TIE over up to 12 measurements for the reference methods. Moreover, miniaturization reduced reagent consumption and residue generation. For example, for in-tip TIE, only 3.6 mL of residues was generated (n = 12) over 60-240 mL in reference methods (n = 3). Contrarily to other TIE methods, no microplates or stirring was required, opening possibilities for field analysis since the multichannel pipette and the infrared camera are both operated with batteries.

A Review on Strut and Tie Methods

Strut and tie method (STM) provides simplified solutions to complicated design problems. It was an evolutionary discovery which lead to an improved understanding of shear and flexural deformations of the structures. STM is applicable to the regions of the structure where beam theory is not valid. Numerous studies were conducted in this field, and various modifications are being attached to the conventional STM. Indeterminate models replaced determinate models, and nonlinear analysis replaced linear elastic analysis. New ideas like automatic generation of models based on optimisation techniques, simplified inelastic analysis using secant stiffness method and 3-dimensional analysis were also introduced. This paper summarises some of these studies and discusses their merits and limitations. Some suggestions to simplify these complicated methods are also included.

Análise de blocos de fundação destinados ao apoio de pilares de geometria complexa

O presente trabalho tem por objetivo estudar o comportamento de blocos de fundação sobre estacas que recebem pilares de geometria complexa. Procura-se avaliar se o dimensionamento simplificado desses casos, utilizando o Método das Bielas, pode ser feito através da substituição da geometria complexa do pilar por uma seção quadrada, rotina essa frequentemente utilizada nos programas comerciais de dimensionamento automático e cercada de grandes dúvidas nos escritórios de projetos estruturais. Para tanto, foram efetuadas análises numéricas para três formatos de pilares (Retangular, em L e em C) e duas configurações de bloco (cinco e nove estacas). Na análise dos diferentes tipos de pilares, verificou-se que a consideração de geometria complexa gerou uma distribuição mais homogênea dos esforços nos blocos de fundação, resultando em campos de tração inferiores e consequentemente em menores taxas de armadura de tração quando comparados com a seção quadrada equivalente. Finalmente, para os blocos de fundação com pilares de geometria complexa investigados, verificou-se que a simplificação da geometria complexa do pilar por uma seção quadrada equivalente pode ser considerada a favor da segurança devido a maior quantidade de armaduras necessárias, validando assim a rotina normalmente adotada de maneira rotineira nos escritórios

A dual pass mortar approach for unbiased constraints and self-contact

A dual pass stabilized mortar contact and mesh tying method is proposed. The method is fully symmetric in that no bias is made when choosing the multiplier space. Using a mesh dependent norm, the approach is shown to satisfy an inf–sup stability condition which is used to develop an a-priori error estimator for the bilateral constraint condition. The method was implemented for 3-D and is applicable to contact constraints with normal pressures and tied constraints with surface tractions. The addition of stabilization requires some special attention to show that the inequality constraints are treatable according to the standard KKT conditions. In fact, it is shown that the proposed scheme is equivalent to a particular form of intermediate surface constraint method. The examples compare the standard single surface mortar with the dual pass approach when applicable. Several sensitivity studies of the stabilization parameter are included in the results. A number of examples include nonlinear kinematics, plasticity and self-contact and all performed well for the proposed approach.

Automatic well tying and wavelet phase estimation with no waveform stretching or squeezing

Well-to-seismic tie and wavelet phase estimation are closely related steps that link geology and seismic data. Usually, these processes are solved separately or alternately, diminishing the quality of the well-tying procedure. Apart from trying different wavelets, the well-to-seismic tie involves shifting and, often, stretching and/or squeezing the synthetic data until the correlation with the observed trace is high. These operations, which are somewhat arbitrary and prone to human errors, may lead to unrealistic velocity models and undesired waveform deformations. The automatic tying method that we propose avoids these issues allowing us to simultaneously adjust the wavelet phase and the velocity log within a predefined tolerance. The problem is solved iteratively by perturbing the observed velocity log and the wavelet phase in a way that leads to an increase of the correlation coefficient between the seismic data and the synthetic seismogram. The velocity log is perturbed smoothly using a function defined by monotonic cubic splines, whereas the wavelet phase is assumed to be an unknown constant. We solve the resulting optimization problem by means of differential evolution, which allows us to have complete control over the allowable velocity changes and guarantees that the measured borehole observations are well-honored. By means of pseudosynthetic and field data examples, we found that our automatic well-to-seismic tying method leads to high correlation values between the synthetic and the observed traces, accurate wavelet phase estimations, and small departures from the observed velocity log. Because it is the time scale that is stretched and/or squeezed and not the synthetic trace itself, as opposed to other automatic and manual well-tying methods, the resulting trace preserves the wavelet shape, a feature that certainly improves seismic data interpretation.

Use of Suture tightening automated device COR-KNOT® for minimally invasive heart valve surgery: Our initial experience in Bangladesh

Background: COR-KNOT® (LSI Solutions, New York, NY, USA) is an automated suture securing device has not been well known. We report a case series for first automated knotting device used for minimally invasive heart valve surgery in Bangladesh. Method and
 Results: To overcome the challenge of knot securing via a Key-Hole surgery we have used CORKNOT ®. The newest device is capable of remotely and automatically secure sutures and simultaneously can cut and remove the excess suture tails. We covered the spectrum of heart valve surgery: There was one case of bioprosthetic aortic valve replacement, one case of mitral valve repair, one case of bioprosthetic mitral valve replacement, one case of failed mitral valve repair with COR-KNOT® explantation followed by mechanical mitral valve replacement and one case of redo-mitral valve replacement. Average length of hospital stays was 5 ± 1days. There was one reopening, one post-operative atrial fibrillation. No wound infection and no 30day mortality.
 Conclusion: We conclude, COR-KNOT® is a safe and effective tool to reduce the duration of operation. Clinical outcome of heart valve surgery with COR-KNOT® is comparable with other methods of suture tying methods.
 Bangladesh Heart Journal 2019; 34(2) : 127-131

X Marks the Knot: Simplified Laparoscopic Intra-Corporeal Knot Tying

Video Objective The objectives of this video are to present a novel technique for simplified laparoscopic intra-corporeal knot tying and to demonstrate the importance of laparoscopic simulation in learning new techniques. Setting Traditional intra-corporeal knot tying can be difficult, depending on the angle of the suture, port placement, or other technical difficulty. Many surgeons have turned to alternatives to circumvent this procedure, including the use of barbed suture, knotless suture re-load devices, Lapra-ty's, and extra-corporeal knot tying. However, this remains an important skill to for the gynecologic surgeon. This video presents a step-by-step technique of a novel intra-corporeal knot tying method. The setting includes both a simulation trainer for laparoscopy and a live surgery. The patient in the surgery is a 48-year-old female with abnormal uterine bleeding undergoing total laparoscopic hysterectomy; we use our laparoscopic knot to reinforce the vaginal cuff closure. Interventions The simplified extra-corporeal knot starts with placement of an interrupted suture. The primary surgeon crosses the suture to create an X, which is stabilized by the assistant surgeon. The primary surgeon passes the tail of the suture through the loop created by the X twice to create a surgeon's knot. The ends are then pulled downward to create a flat knot. This process is repeated. In order to create square knots, the tail should be passed in front of or behind the loop with each alternating throw. Conclusion The simplified intra-corporal knot is a useful resource for surgeons who experience difficulty with traditional laparoscopic knot tying. The maneuvers are intuitive and are similar to open two-handed knot tying. There is a learning curve associated with this procedure, and it is important to practice in a simulated setting. We hope this video will provide an alternative method for surgeons planning to tie intra-corporeal knots.

Competency assessment tool for laparoscopic suturing: development and reliability evaluation

BackgroundLaparoscopic suturing can be technically challenging and requires extensive training to achieve competency. To date no specific and objective assessment method for laparoscopic suturing and knot tying is available that can guide training and monitor performance in these complex surgical skills. In this study we aimed to develop a laparoscopic suturing competency assessment tool (LS-CAT) and assess its inter-observer reliability.MethodsWe developed a bespoke CAT tool for laparoscopic suturing through a structured, mixed methodology approach, overseen by a steering committee with experience in developing surgical assessment tools. A wide Delphi consultation with over twelve experts in laparoscopic surgery guided the development stages of the tool. Following, subjects with different levels of laparoscopic expertise were included to evaluate this tool, using a simulated laparoscopic suturing task which involved placing of two surgical knots. A research assistant video recorded and anonymised each performance. Two blinded expert surgeons assessed the anonymised videos using the developed LS-CAT. The LS-CAT scores of the two experts were compared to assess the inter-observer reliability. Lastly, we compared the subjects’ LS-CAT performance scores at the beginning and end of their learning curve.ResultsThis study evaluated a novel LS-CAT performance tool, comprising of four tasks. Thirty-six complete videos were analysed and evaluated with the LS-CAT, of which the scores demonstrated excellent inter-observer reliability. Cohen’s Kappa analysis revealed good to excellent levels of agreement for almost all tasks of both instrument handling and tissue handling (0.87; 0.77; 0.75; 0.86; 0.85, all with p < 0.001). Subjects performed significantly better at the end of their learning curve compared to their first attempt for all LS-CAT items (all with p < 0.001).ConclusionsWe developed the LS-CAT, which is a laparoscopic suturing grading matrix, with excellent inter-rater reliability and to discriminate between experience levels. This LS-CAT has a potential for wider use to objectively assess laparoscopic suturing skills.

Investigasi Keruntuhan Geser Balok Tinggi Beton Bertulang dan Beton Fiber Dengan Metode Eksperimental, Metode Numerik dan Metode Strut and Tie

One reinforced beam element that experiences a shear failure is a high beam; a beam that follows a requirement based on SNI-2847-2013 standard that have the proportion of sliding span (l) and the effective height (d) not more than three. The type of collapse in high beams generally is shear failure in which the crack appears from the area around the placement, propagates and reaching the maximum value at the point of loading. Observation of crack patterns and ultimate loads can be done by several methods based on both non-linearity and linearity of materials.&#x0D; Two specimens consisted of one high beam conventional reinforced concrete and one high beam concrete fiber with a dimension of 170 mm x 420 mm x 850 mm were prepared. Fiber from machine turning waste was used as coarse aggregate substitution with 100% composition in fiber concrete. Both specimens were tested in the laboratory and observed for crack patterns analysis and ultimate load achievement. The experimental test results were then compared with the numerical test results for the non-linearity properties of the material and the Strut and Tie method for the linearity properties of the material.&#x0D; The ultimate high beam of conventional reinforced concrete when experiencing shear failure in the experimental method, numeric method, and strut and tie method were 310 KN, 290 KN, and 236.917 KN respectively, whereas in the high beam fiber concrete, the ultimate load in the experimental method, numeric method, and in the strut and tie method were 280 KN, 260 KN, and 263,917 KN respectively. The biggest ratio of test results were obtained from the comparison between the numerical and the experimental methods in conventional concrete which was equal to 0.94. This showed the similarity of non-linearity properties of the material to produce adjacent test results.

Vision-Based Surgical Suture Looping Through Trajectory Planning for Wound Suturing

Robot-assisted surgery has revolutionized the field of surgery over the past few decades. Despite many successes, achieving full automation in these surgeries remains a challenging task. In this paper, a dynamic approach is proposed to automate knot tying with an in-house robot vision system. Through efficient path planning and coordination between two grippers, the workspace required for constructing the suture loop can be reduced while issues such as suture slippage and collisions between instruments can be eliminated. Visual images were employed to monitor the two grippers in real time and their positions were evaluated using transformation matrices obtained experimentally. A linear quadratic control scheme was applied to optimize the tracking performance of the two grippers. From the experiments, this visual evaluation method can achieve a position accuracy of 1 mm in the workspace. The proposed algorithm was evaluated and automatic suture looping operation was successfully performed in all six trials. Different parameters in the control scheme were also examined by introducing external impulse disturbances during the knot-tying process. This proposed knot-tying approach demonstrates a simple and efficient way to construct a suture knot in a minimal workspace. Note to Practitioners —A surgical operation usually takes several hours to complete, which is a test of surgeon’s endurance. To better assist surgeons, several repetitive surgical tasks can be performed automatically with a robotic system. This paper presents a new method for robot-assisted surgical knot tying in a confined environment. Through simultaneous manipulation and trajectory planning of the two surgical grippers, suture loops were constructed while keeping the suture in tension. Images were employed to guide the gripers in completing the knot-tying process with high precision. Experiments were conducted to demonstrate the automated suture looping operation with the system and the proposed method. The robustness of the method was also examined by introducing impulse disturbances and occlusions during the experiments. This proposed method does not require complicated hardware setup, allowing easy implementations on various surgical systems.

Comparing Postoperative Complication of LigaSure Small Jaw Instrument with Clamp and Tie Method in Thyroidectomy Patients: A Randomized Controlled Trial

Comparing Postoperative Complication of LigaSure Small Jaw Instrument with Clamp and Tie Method in Thyroidectomy Patients: A Randomized Controlled Trial

Experimental and theoretical investigation of crack width calculation methods for RC ties

This paper theoretically and experimentally investigates the semi‐empirical formulas recommended by Eurocode 2 (EC2), fib Model Code 2010 (MC2010), and Eurocode 2 with the German National Annex (DIN) for calculating crack widths in reinforced concrete. It is shown that the formulas can be derived from the principles for the idealized behavior of RC ties. However, instead of explicitly solving the resulting differential equations, the use of simplifications leads to inconsistent formulas. An experimental study was carried out involving the testing of eight RC ties to discover the modeling uncertainty of the formulas. It was found that EC2 substantially overestimated the crack widths for the RC ties. MC2010 and DIN seemed to predict the crack widths better, but gave rather a large number of nonconservative crack width predictions. These experimental results, combined with the theoretical study, suggest that a more consistent calculation model should be formulated by explicitly solving the resulting differential equation.

Strut and Tie Modeling for RC Deep Beams under non-Central Loadings

This work aims at presenting detailed procedures companied by numerical examples for analyzing and designing reinforced concrete deep beams that subjected to non-central loadings based on Strut and Tie method (STM). The subjected loadings were moved from the center of the beam span towards the supports reaching the maximum non-centrality could be achieved (after which the beams became ‘not deep’ from ACI 318M-14 point of view). A total of three deep beams with three different types of loadings were taken into considerations; one concentrated force, two concentrated forces and uniformly distributed load. Every specimen had a cross section of 150 400 mm and a total length of 1000 mm. Generally, it was found that moving load from the span center towards one of the supports leads to worth notable decreases in the beam ultimate capacity. Therefore, in the case of one-concentrated force, the ultimate load capacity decreased by 30.2% when left shear span to effective depth ratio (aL/d) decreased from 1.3 to 0.65. While in the cases of two-concentrated forces or uniformly distributed loading, it was found that changing (aL/d) ratio from 1.02 to 0.37 led to decrease the deep beam ultimate capacity by 30.5%.

A time-saving method for sealing Purdue Improved Crop Storage (PICS) bags

Purdue Improved Crop Storage (PICS) bags were designed to reduce grain storage losses on smallholder farms. The bag consists of three layers: two high-density polyethylene liners fitted inside a woven polypropylene bag. Recently, farmer groups, development relief programs, and government food security agencies have shown interest in PICS bags for large-scale use. PICS bags are conventionally closed by a twist-tie (TT) method, which involves twisting, folding, and tying the lip of each layer individually with a cord. This is not only time and labor intensive, but also may affect the integrity of the liners. We evaluated three new bag closure methods: i) inner liner rolled onto itself and middle liner fold-tied (IR), ii) both liners folded together and tied (FT), and iii) both liners folded and tied separately (FS), along with the conventional twist tie (TT) method. The time to close partially or fully filled 50 kg-capacity PICS bags filled with maize grain was assessed. Results showed that FT was the most time-saving method, reducing bag sealing time by >34% versus the usual TT method. The average internal oxygen levels reached <2% within a week in bags containing grain highly infested with Sitophilus zeamais, while it remained >5% levels for less-infested bags. In both cases, insect population growth was suppressed. Oxygen depletion rates among tying methods remained the same regardless of the closure method used. When large numbers of bags need to be closed, the time-saving FT method is a good alternative PICS sealing method over the conventional twist-tie approach.

Investigation of Corbels Designed According to Strut-and- Tie and Empirical Methods

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Enhanced mesoscale partitioned modelling of heterogeneous masonry structures

SummaryThis paper presents an accurate and efficient computational strategy for the 3‐dimensional simulation of heterogeneous structures with unreinforced masonry components. A mesoscale modelling approach is employed for the unreinforced masonry parts, whereas other material components are modelled independently with continuous meshes. The generally nonmatching meshes of the distinct domains are coupled with the use of a mesh tying method. The physical interaction between the components is captured with the use of zero‐thickness cohesive interface elements. This strategy enables the optimisation of the individual meshes leading to increased computational efficiency. Furthermore, the elimination of the mesh compatibility requirement allows the 3‐dimensional modelling of complex heterogeneous structures, ensuring accurate representation of each component's nonlinear behaviour and their interaction. Numerical examples, including a comparative analysis on the elastic and nonlinear response of a masonry bridge considering arch‐backfill interaction and the nonlinear simulation of a multileaf wall, are presented to show the unique features of the proposed strategy and its predictive power in comparison with experimental and numerical results found in the literature.