Development of innovative hybrid sandwich panel slabs: Experimental results

The authors appreciate the collaboration of the following labs: Civitest for developing DHCC materials, PIEP for conducting VARTM process (Eng. Luis Oliveira) and Department of Civil Engineering of Minho University to perform the tests (Mr. Antonio Matos and Eng. Marco Jorge).In this paper, a new generation of composite sandwich slab is proposed as a solution for the rehabilitation of slabs in old masonry buildings. An innovative solution was developed during this research formed by four components: a Deflection Hardening Cement Composite (DHCC) layer on the top compression skin, a glass fiber reinforced polymer (GFRP) skin at the bottom tension surface, GFRP ribs to transfer shear from top to bottom layers, and foam core for thermal-insolation purposes. The DHCC layer contributes significantly for the load carrying and deflection capacity due to its stiffness, compressive strength and toughness, offers resistance to the occurrence of buckling phenomena in the GFRP ribs, improves the performance of this structural concept against impact and fire, and constitutes an excellent medium for the application of finishing materials, like ceramics or timber. Two different hybrid composite slabs were developed and tested, and their behavior was assessed under flexural loading. The results showed that the developed hybrid sandwich slabs accomplish all design requisites for serviceability and ultimate limit states, and assure a stiffness/dead-weight and load-capacity/dead-weight ratios much higher than conventional structural slab systems.FCT - Fundação para a Ciência e Tecnologi

Assessment of the durability performance of fiber-cement sheets

According to standards, the durability performance of fiber-cement sheets must be evaluated by comparing the modulus of rupture (MOR) before and after durability tests (freeze-thaw, soak-dry, and warm water) are completed. This paper investigated the MOR of two different fiber-cement sheets samples before and after durability tests as well as its ductility and toughness. Results showed no significant difference between the MOR of control specimens and that of the specimens submitted to durability tests except in the case of the freezing and thawing test where after 100 cycles, a 7–9% decrease was observed. The differences between the MOR of the control specimens and that of the specimens submitted to durability tests were negligible and acceptable in accordance to the requirements of the standard. However, toughness and ductility decreased considerably in specimens of sample 1 by 25, 35, and 15%, respectively, when exposed to soak-dry (25 and 50 cycles) and warm water conditions. In turn, the reduction in toughness and ductility for specimens of sample 2 exposed to soak-dry (50 cycles) and warm water conditions were of 40 and 7%, respectively. The results of this investigation suggest that ductility and toughness should also be considered to assess the durability performance of fiber-cement sheets

Отношение членов реанимационной бригады и сопровождающих пациента лиц к присутствию родственников пациента первой степени родства во время сердечно-легочной реанимации в отделениях неотложной помощи

The presence of the patient’s family at their bedside during cardiopulmonary resuscitation (CPR) is one of the challenging issues that has been frequently taken into consideration. Considering the importance of this topic. The objective of the present study was conducted to determine the attitude of the CPR team members and the patient’s companions toward the presence of the patient’s first-degree relatives during CPR.Materials and methods. The descriptive-analytical cross-sectional study was conducted on 100 CPR team members of two University Hospitals and 120 near relatives of patients undergoing CPR in 2021. The data were collected by the researcher-made questionnaire and depression, anxiety, stress scale (DASS) during CPR. The collected data were analyzed by SPSS (version 22) statistical software.Results. From the perspective of both the CPR team members and the patient’s companions, the highest mean response was related to the fact that it would be better for the patient to agree on the presence or absence of their family before hospitalization and whether they have favorable conditions. The attitude toward the presence of the patient’s family during CPR was statistically significantly associated with the companions’ gender (p < 0.05) and with the experience of work and participation in CPR of the CPR team members (p < 0.05).Conclusion. Taking into account the different opinions of the CPR team members and the patient’s relatives about the presence of family during resuscitation, additional studies with a large sample size should be carried out.Присутствие семьи пациента у его постели во время проведения сердечно-легочной реанимации (СЛР) является одним из вопросов, привлекающих внимание. Настоящее исследование было проведено с целью определения отношения членов реанимационной бригады и сопровождающих пациента лиц к присутствию родственников пациента первой степени родства во время проведения СЛР.Материалы и методы. Описательно-аналитическое перекрестное исследование проведено в 2 университетских больницах с участием 100 членов команд, проводящих СЛР, и 120 близких родственников пациентов, которым проводили СЛР в 2021 г. Данные были собраны с помощью разработанного исследователем опросника и шкалы стресса, тревоги и депрессии (DASS) во время СЛР. Собранные данные были проанализированы с помощью статистического программного обеспечения SPSS (версия 22).Результаты. С точки зрения как членов команды, проводящей СЛР, так и близких пациента, наиболее значимым был вопрос о том, что самому пациенту было бы лучше договориться о присутствии или отсутствии своей семьи еще до момента госпитализации и выяснить, насколько для этого созданы благоприятные условия. Отношение к присутствию семьи пациента во время СЛР было статистически значимо связано с полом сопровождающего (р < 0,05) и с опытом работы и участия в СЛР членов реанимационной бригады (р < 0,05).Вывод. Учитывая различные мнения членов команды, проводящей СЛР, и близких пациента относительно присутствия семьи во время реанимации, следует провести дополнительные исследования с большим объемом выборки

Evaluation of adhesion in polymeric fibre reinforced cementitious composites

In this study adhesion of some polymeric fibres to a cement matrix was evaluated both by a theoretical and by an experimental approach. In common methods adhesion of the fibres to the cementitious materials is determined by pull-out test. This test evaluates the energy failure during the fibre drawing out. This paper analyzes the adhesion theory for fibre reinforced cementitious composites to separate the share of the chemical and mechanical adhesion expressing new parameters, which are effective in the adhesion behaviour. Explanations about how the different fibres, matrix properties, test factors and environmental conditions can affect the adhesion results are given. It was found that for fibre/cement composites the fracture energy due to the interfacial interactions is for several orders of magnitude smaller that the polymeric fibre losses function. By employing adhesion theory, fibre/cement interac- tions are better described by a simple relationship of their surface free energy. Determination of the loss function (energy dissipation) leads us to predict the fibre behaviour in the cement matrix and the selection of the appropriate reinforcement

Cementitious composites reinforced with polypropylene, nylon and polyacrylonitile fibres

This paper compares the adhesion strength between three polymeric fibres (polypropylene (PP), nylon66 (N66) and polyacrylonitrile (PAN)) embedded in a cement paste. The specimens were prepared at a water to cement ratio (w/c) of 0.5, and tested after 7, 14 and 28 curing days. It was found that although the adhesion between the polymeric fibres to the cement matrix is an important factor, the energy absorption capacity or energy dissipation ability of the fibres plays a more important role in the improvement of the cementitious composites fracture toughness. Scanning electron micrographs was used to characterize the fibres surface before and after the Pullout tests

Influence of acrylic fibers geometry on the mechanical performance of fiber-cement composites

This article analyses the influence of acrylic fibers shape on the flexural behavior of cement composite. The fibers differ in their cross-sectional shapes due to the spinning process (wet-spun and dry-spun). The fibers were characterized by optical microscopy, and the shape factors were calculated on the basis of their geometric characteristics. Results showed that both types of acrylic fiber remarkably improved the flexural performance of the composites. Wet-spun acrylic fibers lead to high flexural strength and toughness. It was found that by increasing the fibers’ shape factor by a factor of 10%, flexural strength and toughness increase to 26% and 23%, respectively

Fuchs Heterochromic Iridocyclitis-Associated Glaucoma: A Retrospective Comparison of Primary Ahmed Glaucoma Valve implantation and Trabeculectomy with MMC

Purpose: To compare the safety and efficacy of a primary trabeculectomy with mitomycin C (T) and an Ahmed glaucoma valve (AGV) implantation in patients with Fuchs heterochromic iridocyclitis (FHIC) related glaucoma, a rare complication of an uncommon form of uveitis. Design: Retrospective comparative case series. Method: Twenty-six patients with uncontrolled FHIC-associated glaucoma received T (n=12) or an AGV (n=14). Primary outcome measures were the surgical success defined as IOP ≤ 21 mmHg and decreased ≥ 20% from the baseline and no secondary glaucoma surgery. Secondary outcome measures were the number of glaucoma medications, complications, best corrected visual acuity (BCVA), and intraocular pressure. Results: The follow-up (mean±SD) was 34.0±17.7 in T and 33.4±18.6 months in AGV (p = 0.837). The cumulative probability of success rate at the final follow-up at three years was 41.7% for T and 85.7% for AGV. There was no significant difference in complications between the two groups (P>0.05). The mean preoperative IOP in T was 23.4±3.3 mmHg and 21.6±5.2 mmHg at the final visit (P= 0.041). In AGV, the preoperative IOP was 24±7.8 and 17.1±2.6 mmHg at the final visit (P= 0.003), respectively. AGV had a significantly lower average IOP at the final follow-up visit compared to T (P= 0.018). The number of glaucoma medications at baseline was 3.3±0.5 in T and 3±0.6 in AGV (P= 0.233). This decreased significantly to 2.4±1.0 and 1.7±0.6 at the final follow-up (P= 0.008 and 0.002, respectively). Patients in AGV needed fewer glaucoma medications (P= 0.041). BCVA was equal in both groups and did not change (p>0.05). Conclusion: Primary AGV had a higher success rate than T in the management of FHIC-associated glaucoma. The risk of cataract formation and progression was significantly higher following T in these patients

A monte carlo platform for characterization of x-ray radiation dose in ct imaging

Background: Computed tomography (CT) is currently known as a versatile imaging tool in the clinic used for almost all types of cancers. The major issue of CT is the health risk, belonging to X-ray radiation exposure. Concerning this, Monte Carlo (MC) simulation is recognized as a key computational technique for estimating and optimizing radiation dose. CT simulation with MCNP/MCNPX MC code has an inherent problem due to the lack of a fan-beam shaped source model. This limitation increases the run time and highly decreases the number of photons passing the body or phantom. Recently, a beta version of MCNP code called MCNP-FBSM (Fan-Beam Source Model) has been developed to pave the simulation way of CT imaging procedure, removing the need of the collimator. This is a new code, which needs to be validated in all aspects. Objective: In this work, we aimed to develop and validate an efficient computational platform based on modified MCNP-FBSM for CT dosimetry purposes. Material and Methods: In this experimental study, a setup is carried out to measure CTDI100 in air and standard dosimetry phantoms. The accuracy of the developed MC CT simulator results has been widely benchmarked through comparison with our measured data, UK�s National Health Service�s reports (known as ImPACT), manufacturer�s data, and other published results. Results: The minimum and maximum observed mean differences of our simulation results and other above-mentioned data were the 1.5, and 9.79, respectively. Conclusion: The developed FBSM MC computational platform is a beneficial tool for CT dosimetry. © 2021, Shriaz University of Medical Sciences. All rights reserved