scholarly journals Which experimental procedures influence the apparent proximal femoral stiffness? A parametric study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Morteza Amini ◽  
Andreas Reisinger ◽  
Lena Hirtler ◽  
Dieter Pahr
Keyword(s):  
Experimental Validation ◽  
Testing Machine ◽  
Ct Scanning ◽  
Loading Direction ◽  
Apparent Stiffness ◽  
Experimental Parameters ◽  
Fresh Frozen ◽  
Multiple Loading ◽  
The Impact ◽  
Influential Parameters

Abstract Background Experimental validation is the gold standard for the development of FE predictive models of bone. Employing multiple loading directions could improve this process. To capture the correct directional response of a sample, the effect of all influential parameters should be systematically considered. This study aims to determine the impact of common experimental parameters on the proximal femur’s apparent stiffness. Methods To that end, a parametric approach was taken to study the effects of: repetition, pre-loading, re-adjustment, re-fixation, storage, and μCT scanning as random sources of uncertainties, and loading direction as the controlled source of variation in both stand and side-fall configurations. Ten fresh-frozen proximal femoral specimens were prepared and tested with a novel setup in three consecutive sets of experiments. The neutral state and 15-degree abduction and adduction angles in both stance and fall configurations were tested for all samples and parameters. The apparent stiffness of the samples was measured using load-displacement data from the testing machine and validated against marker displacement data tracked by DIC cameras. Results Among the sources of uncertainties, only the storage cycle affected the proximal femoral apparent stiffness significantly. The random effects of setup manipulation and intermittent μCT scanning were negligible. The 15∘ deviation in loading direction had a significant effect comparable in size to that of switching the loading configuration from neutral stance to neutral side-fall. Conclusion According to these results, comparisons between the stiffness of the samples under various loading scenarios can be made if there are no storage intervals between the different load cases on the same samples. These outcomes could be used as guidance in defining a highly repeatable and multi-directional experimental validation study protocol.

scholarly journals Simultaneous Casualty Admissions—Do they Affect Treatment in the Receiving Trauma Center?

2021 ◽  
Author(s):  
Michel Paul Johan Teuben ◽  
Carsten Mand ◽  
Laura Moosdorf ◽  
Kai Sprengel ◽  
Alba Shehu ◽  
...  
Keyword(s):  
Injury Severity ◽  
Damage Control ◽  
Ct Scanning ◽  
Mortality Rates ◽  
Trauma Centers ◽  
Simultaneous Treatment ◽  
Diagnostic Pathway ◽  
Injured Patients ◽  
The Impact ◽  
Mean Time

Abstract Background Simultaneous trauma admissions expose medical professionals to increased workload. The impact of simultaneous trauma admissions on hospital allocation, therapy, and outcome is currently unclear. We hypothesized that multiple admission-scenarios impact the diagnostic pathway and outcome. Methods The TraumaRegister DGU® was utilized. Patients admitted between 2002–2015 with an ISS ≥ 9, treated with ATLS®- algorithms were included. Group ´IND´ included individual admissions, two individuals that were admitted within 60 min of each other were selected for group ´MULT´. Patients admitted within 10 min were considered as simultaneous (´SIM´) admissions. We compared patient and trauma characteristics, treatment, and outcomes between both groups. Results 132,382 admissions were included, and 4,462/3.4% MULTiple admissions were found. The SIM-group contained 1,686/1.3% patients. The overall median injury severity score was 17 and a mean age of 48 years was found. MULT patients were more frequently admitted to level-one trauma centers (68%) than individual trauma admissions were (58%, p < 0.001). Mean time to CT-scanning (24 vs. 26/28 min) was longer in MULT / SIM patients compared to individual admissions. No differences in utilization of damage control principles were seen. Moreover, mortality rates did not differ between the groups (13.1% in regular admissions and 11.4%/10,6% in MULT/SIM patients). Conclusion This study demonstrates that simultaneous treatment of injured patients is rare. Individuals treated in parallel with other patients were more often admitted to level-one trauma centers compared with individual patients. Although diagnostics take longer, treatment principles and mortality are equal in individual admissions and simultaneously admitted patients. More studies are required to optimize health care under these conditions.

scholarly journals Outcome of Major Hemorrhage at a Major Cardiothoracic Center in Patients with Activated Major Hemorrhage Protocol versus Nonactivated Protocol

2021 ◽  
Vol 47 (01) ◽  
pp. 074-083
Author(s):  
Kathryn W. Chang ◽  
Steve Owen ◽  
Michaela Gaspar ◽  
Mike Laffan ◽  
Deepa R. J. Arachchillage
Keyword(s):  
Fresh Frozen Plasma ◽  
Electronic Records ◽  
Blood Products ◽  
Major Hemorrhage ◽  
Fresh Frozen ◽  
Dilutional Coagulopathy ◽  
Baseline Characteristics ◽  
The Impact ◽  
Frozen Plasma ◽  
Baseline Hemoglobin

AbstractThis study aimed to determine the impact of major hemorrhage (MH) protocol (MHP) activation on blood administration and patient outcome at a UK major cardiothoracic center. MH was defined in patients (> 16 years) as those who received > 5 units of red blood cells (RBCs) in < 4 hours, or > 10 units in 24 hours. Data were collected retrospectively from patient electronic records and hospital transfusion databases recording issue of blood products from January 2016 to December 2018. Of 134 patients with MH, 24 had activated MHP and 110 did not have activated MHP. Groups were similar for age, sex, baseline hemoglobin, platelet count, coagulation screen, and renal function with no difference in the baseline clinical characteristics. The total number of red cell units (median and [IQR]) transfused was no different in the patients with activated (7.5 [5–11.75]) versus nonactivated (9 [6–12]) MHP (p = 0.35). Patients in the nonactivated MHP group received significantly higher number of platelet units (median: 3 vs. 2, p = 0.014), plasma (median: 4.5 vs. 1.5, p = 0.0007), and cryoprecipitate (median: 2 vs. 1, p = 0.008). However, activation of MHP was associated with higher mortality at 24 hours compared with patients with nonactivation of MHP (33.3 vs. 10.9%, p = 0.005) and 30 days (58.3 vs. 30.9%, p = 0.01). The total RBC and platelet (but not fresh frozen plasma [FFP]) units received were higher in deceased patients than in survivors. Increased mortality was associated with a higher RBC:FFP ratio. Only 26% of patients received tranexamic acid and these patients had higher mortality at 30 days but not at 24 hours. Deceased patients at 30 days had higher levels of fibrinogen than those who survived (median: 2.4 vs. 1.8, p = 0.01). Patients with activated MHP had significantly higher mortality at both 24 hours and 30 days despite lack of difference in the baseline characteristics of the patients with activated MHP versus nonactivated MHP groups. The increased mortality associated with a higher RBC:FFP ratio suggests dilutional coagulopathy may contribute to mortality, but higher fibrinogen at baseline was not protective.

scholarly journals A flexible ChIP-sequencing simulation toolkit

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
An Zheng ◽  
Michael Lamkin ◽  
Yutong Qiu ◽  
Kevin Ren ◽  
Alon Goren ◽  
...  
Keyword(s):  
Ground Truth ◽  
Peak Calling ◽  
Simulation Framework ◽  
Experimental Conditions ◽  
Ground Truth Data ◽  
Chip Sequencing ◽  
Genome Wide ◽  
Experimental Parameters ◽  
Differential Binding ◽  
The Impact

Abstract Background A major challenge in evaluating quantitative ChIP-seq analyses, such as peak calling and differential binding, is a lack of reliable ground truth data. Accurate simulation of ChIP-seq data can mitigate this challenge, but existing frameworks are either too cumbersome to apply genome-wide or unable to model a number of important experimental conditions in ChIP-seq. Results We present ChIPs, a toolkit for rapidly simulating ChIP-seq data using statistical models of key experimental steps. We demonstrate how ChIPs can be used for a range of applications, including benchmarking analysis tools and evaluating the impact of various experimental parameters. ChIPs is implemented as a standalone command-line program written in C++ and is available from https://github.com/gymreklab/chips. Conclusions ChIPs is an efficient ChIP-seq simulation framework that generates realistic datasets over a flexible range of experimental conditions. It can serve as an important component in various ChIP-seq analyses where ground truth data are needed.

scholarly journals Effects of temperature and impactor nose diameter on the impact behavior of PA6 and PP thermoplastic composites

2018 ◽  
Vol 51 (1) ◽  
pp. 64-74 ◽  
Author(s):  
Akar Dogan ◽  
Yusuf Arman
Keyword(s):  
Load Capacity ◽  
Testing Machine ◽  
Polyamide 6 ◽  
Impact Testing ◽  
Impact Behavior ◽  
Thermoplastic Composites ◽  
Test Machine ◽  
Effects Of Temperature ◽  
Impact Energies ◽  
The Impact

In this study, the effects of temperature and impactor nose diameter on the impact behavior of woven glass-reinforced polyamide 6 (PA6) and polypropylene (PP) thermoplastic composites were investigated experimentally. Impact energies are chosen as 10, 30, 50, 70, 90, 110, 130, and 170 J. The thickness of composite materials is 4 mm. Impact tests were performed using a drop weight impact testing machine, CEAST-Fractovis Plus, and the load capacity of test machine is 22 kN. Hemispherical impactor nose diameter of 12, 7, and 20 mm were used as an impactor. The tests are conducted at room temperature (20°C and 75°C). As a result, the PP composites of the same thickness absorbed more energy than PA6 composites. The amount of absorbed energy of PP and PA6 composites decreased with temperature.

Harvest Site and Loading Direction as Determinants of the Flexural Rigidity of Human Fibular Bone Grafts

1998 ◽  
Vol 02 (04) ◽  
pp. 273-281
Author(s):  
Anneliese D. Heiner ◽  
Yongde Zhang ◽  
Douglas R. Pedersen ◽  
Thomas D. Brown
Keyword(s):  
Flexural Rigidity ◽  
Bone Grafts ◽  
Fibular Graft ◽  
Loading Direction ◽  
Fresh Frozen ◽  
Bending Loads ◽  
Flexural Tests ◽  
Harvest Site ◽  
Optimal Site ◽  
Anterior Posterior

Segments of fibula commonly used as cortical bone grafts need to support functional loading at their host site. Since many such constructs require the fibula to carry appreciable bending loads, we undertook a series of flexural tests to determine how flexural rigidity of the fibula varies with longitudinal (or harvest) site and loading direction. Ten fresh-frozen human fibulas were tested in a 4-point bending fixture. The fibulas were tested at three longitudinal sites (centered at 1/4, 1/2 and 3/4 lengths) and in each of four anatomic directions (anterior, posterior, medial and lateral). There were consistent longitudinal and directional variations in flexural rigidity. The central site was about twice as stiff as the proximal and distal sites, for both the A-P and M-L directions (p < 0.05), indicating that the center of the fibula is the optimal site for harvesting grafts that will be subjected to severe bending. The A-P direction was stiffer in bending than the M-L direction, by 43%, 52%, and 86% for the proximal, central, and distal sites (p < 0.05 for the central and distal sites only), indicating that the choice of circumferential orientation of a fibular graft at the host site could have an appreciable influence on construct rigidity.

Effect of Hydrogen Content on Impact Property of A357 Alloy

2011 ◽  
Vol 704-705 ◽  
pp. 1201-1204 ◽  
Author(s):  
Yang Li ◽  
Zheng Bing Xu ◽  
Jian Min Zeng
Keyword(s):  
Crack Propagation ◽  
Hydrogen Content ◽  
Impact Test ◽  
Testing Machine ◽  
Initial Crack ◽  
Impact Testing ◽  
Total Absorption ◽  
A357 Alloy ◽  
Absorption Energy ◽  
The Impact

The impact specimens with different hydrogen contents were solution treated at 540±3°C for 12h; water quenched at 60-100°C; and aged at 165±1°C for 6h. The impact test was carried out at Roell450 pendulum impact testing machine. The impact test results show that the impact energy has strong relation with the hydrogen content. The total absorption energy increases with the increasing of hydrogen content. The crack propagation energy Avp and present larger proportion than the initial crack energy Avi in the total absorption energy Av. The number of the pinholes increases and the pinholes turn from smaller irregular ones into sub-circular shape ones. The specimen with irregular sub-circular pinholes has larger KI, and has more crack propagation resistance.

scholarly journals The Impact of Chlorhexidine Mouth Rinse on the Bond Strength of Polycarbonate Orthodontic Brackets

2014 ◽  
Vol 15 (6) ◽  
pp. 688-692 ◽  
Author(s):  
Sukumaran Anil ◽  
Farouk Ahmed Hussein ◽  
Mohammed Ibrahim Hashem ◽  
Elna P Chalisserry
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Testing Machine ◽  
Test Group ◽  
Orthodontic Brackets ◽  
Control Group ◽  
Mouth Rinse ◽  
Significant Difference ◽  
Bond Strengths ◽  
The Impact

ABSTRACT Objective The purpose of the current in-vivo study was to assess the effect of using 0.12% chlorhexidine (CHX) mouth rinse, before bonding, on shear bond strength of polycarbonate brackets bonded with composite adhesive. Subjects and methods Eighteen orthodontic patients with a mean age 21.41 ± 1.2 years, who were scheduled to have 2 or more first premolars extracted, were included in this study. Patients were referred for an oral prophylaxis program which included, in part, the use of a mouth rinse. Patients were divided into 2 groups, a test group of 9 patients who used 0.12% CHX gluconate mouth rinse twice daily and a control group of 9 patients who used a mouth rinse without CHX, but with same color. After 1 week, polycarbonate brackets were bonded to first premolars with Transbond XT composite adhesive. Premolars were extracted after 28 days and tested for shear bond strength on a universal testing machine. Student's t-test was used to compare shear bond strengths of both groups. Results No statistically significant difference was found in bond strengths’ values between both groups. The test group (with CHX) has mean shear bond strength of 14.21 ± 2.42 MPa whereas the control group (without CHX) revealed a mean strength of 14.52 ± 2.31 MPa. Conclusion The use of 0.12% CHX mouth rinse, for one week before bonding, did not affect the shear bond strength of polycarbonate brackets bonded with Transbond composite. Furthermore, these brackets showed clinically acceptable bond strength. How to cite this article Hussein FA, Hashem MI, Chalisserry EP, Anil S. The Impact of Chlorhexidine Mouth Rinse on the Bond Strength of Polycarbonate Orthodontic Brackets. J Contemp Dent Pract 2014;15(6):688-692.

scholarly journals Investigation of the influence of recyclate content on Poisson number of composites

2021 ◽  
Vol 28 (1) ◽  
pp. 668-675
Author(s):  
Daria Żuk ◽  
Norbert Abramczyk ◽  
Sebastian Drewing
Keyword(s):  
Testing Machine ◽  
Solid Material ◽  
Measuring System ◽  
Variable Load ◽  
Low Weight ◽  
Mechanical And Physical Properties ◽  
Static Tensile ◽  
Composite Production ◽  
The Impact ◽  
Made In

Abstract Composite materials are used in many industries. Their mechanical and physical properties as well as their low weight make them suitable for use in many constructions. Their wide application generates a problem with their disposal. Therefore, it is necessary to design new materials based on waste from polyester–glass laminates in order to introduce a closed circuit in the composite production process. The article presents research aimed at determining solid material composites with polyester–glass recyclate, in order to use these materials for modeling the structure. The aim of this study was to determine the effect of the addition of recyclate to the polyester–glass composite on the deformation and the value of the Poisson number of the material. During the study, samples from composites with the addition of polyester–glass recyclate were used. Samples made in accordance with the standard for plastics PN-EN ISO 527-4_2000P were subjected to static tensile test on a universal testing machine, with variable load parameters. During the test, the longitudinal and transverse elongations of the samples were measured using a strain gauge measuring system. On the basis of the measurements, the values of Poisson numbers were determined, which allowed for a preliminary assessment of the impact of the recyclate content in the composite on its deformability.

scholarly journals Evaluation of Mechanical, Microstructures and Wear Behaviours of Aluminium Alloy Reinforced with Mussel Shell Powder for Automobile Applications

2021 ◽  
Vol 67 (1-2) ◽  
pp. 27-35
Author(s):  
Idawu Yakubu Suleiman ◽  
Auwal Kasim ◽  
Abdullahi Tanko Mohammed ◽  
Munir Zubairu Sirajo
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloy ◽  
Automobile Industry ◽  
Testing Machine ◽  
Wear Testing ◽  
Wear Behaviour ◽  
Mussel Shell ◽  
The Matrix ◽  
The Impact ◽  
Shell Powder

This paper aims to investigate the mechanical (tensile, hardness, impact, elongation), microstructure and wear behaviours of aluminium alloy reinforced with mussel shell powder (MSP) at different weight percentages (0 wt. % to 15 wt. %) at 3 wt. % interval. The mussel shell powder was characterized by X-ray fluorescence (XRF). The matrix and the composites’ morphology were studied using a scanning electron microscope attached with energy dispersive spectroscopy for the distribution of mussel shell powder particles within the matrix. The wear behaviour of the alloy and composites produced at various reinforcements were carried out using a Taber abrasion wear-testing machine. The XRF showed the compositions of MSP to contain calcium oxide (95.70 %), silica (0.83 %) and others. Mechanical properties showed that tensile values increase with increases in MSP, hardness value increases from 6 wt. % to 15 wt. % of MSP. The impact energy decreased from 42.6 J at 3 wt. % to 22.6 J at 15 wt. %; the percentage elongation also decreased from 37.4 % at 3 wt. % to 20.5 % at 15 wt. % MSP, respectively. The bending stress results increase with increases in the percentage of reinforcement. The morphologies revealed that uniform distribution of MSP within the matrix resulted to improvement in mechanical properties. The wear resistance of the composites increases with increase in the applied load and decreases with increases in the weight percentage of MSP and can be used in the production of brake pads and insulators in the automobile industry.

scholarly journals Uptake of p-Nitrophenol (PNP) from model aqueous solutions using raw and quaternised Afromomum melegueta peels

2020 ◽  
Vol 1 (1) ◽  
pp. 1-8
Author(s):  
J. Ndiritu ◽  
I W. Mwangi ◽  
J. I. Murungi ◽  
R. N. Wanjau
Keyword(s):  
Quaternary Ammonium ◽  
Anthropogenic Activities ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Ammonium Compound ◽  
Cellulose Structure ◽  
Experimental Parameters ◽  
Ftir Technique ◽  
Design Simplicity ◽  
The Impact

 Anthropogenic activities contribute large amounts of pollutants to the environment which threaten animal and human health. There is increased realization of the effect of these toxins on surface and ground water, consequently, their elimination is vital in rendering secure water for drinking as well as culpable release of effluents to our habitats. Phenolic compounds cause serious health effects to both humans and animals; a p-Nitrophenol concentration of 1 ppb changes the taste and odour of water as well as meat and fish quality. In humans, exposure to PNP causes eye and skin burns while its interaction with blood leads to confusion, cyanosis and unconsciousness. It is imperative therefore to find ways for removing PNP from water. Among the available techniques for removing PNP from water, adsorption is more convenient and offers more advantages because of its design, simplicity, and operating flexibility. The present study involved application of peels of raw Afromomum melegueta (RAM) and quaternised Afromomum melegueta (QAM) to remove PNP from water through adsorption. The raw adsorbents were modified with a quaternary ammonium salt to improve their uptake efficiency. The impact of experimental parameters; contact time, pH, sorbent dose, temperature and concentration were investigated. Attenuated FTIR technique was employed to characterize the adsorbent materials. It was established that the quaternary ammonium compound was anchored chemically within the cellulose structure of Afromomum melegueta peels. The behavior of adsorption of PNP was investigated using Langmuir and Freundlich isotherm models. The physical sorption load was 8.70 and 106.38 mg/g for RAM and QAM peels respectively from Langmuir adsorption equation. Uptake of PNP is high at the first 30 mins of contact and at sorbent dosage of 0.01 g and 0.03 g for RAM and QAM respectively. Quantity of PNP removed increases as the initial concentration rises however, adsorption decreases after a concentration exceeding 30 mg/L. The ideal pH and temperature for PNP removal is at pH 3 and 25 ˚C respectively. In conclusion, the findings suggest that Afromomum melegueta peels can be friendly to the environment, cheap biosorbents and efficient which can be applied for the uptake of PNP from drinking water

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