•High-strength, built-up box columns are investigated under lateral drift and axial compression.•Six column specimens are designed with different b/t and P/Py ratios per AISC 341 and AIJ.•Cyclic ...backbone curves for built-up box columns are proposed using 42 test data.•The proposed formulation improves predictions based on ASCE 41 (2013) and NIST (2017).
The AISC 341 (2016) has a more stringent width-to-thickness (b/t) limit for highly ductile hollow box columns (HBCs) than the AIJ (2010) or Taiwan Code (2010), resulting in significant thickness difference in design. Moreover, the cyclic backbone curves based on ASCE 41 (2013) and NIST (2017) underestimate the post-buckling flexural strength of HBCs, particularly in high axial compression force. This paper presents test results of six full-scale, built-up HBCs using SM 570 M steel with the actual yield strength of 460–530 MPa. The lateral cyclic behavior of built-up columns was studied in terms of different b/t ratios, magnitudes of axial compression forces, and lateral drift histories (i.e., cyclically symmetric versus near-fault displacement histories). The built-up box columns were 290–400 mm wide with b/t ratios from 11 to 21, 4000 mm high, and tested laterally with both ends fixed after under a constant axial compression force, 2591–7935 kN. The HBC specimens which were designed based on the highly ductile member requirement in AISC 341 (2016), even under an axial compression force (=40%Py), performed satisfactorily at 4% drift and experienced flange and web fracture at 5% drift. However, the HBC specimens that satisfied the most compact b/t requirement in AIJ (2010) or Taiwan code (2010) did not perform well at 4% drift, losing the axial capacity after significant column local buckling and shortening. The gathered test data, supported by more test data in this work, were analyzed by a multiple regression method to obtain empirical formulations for predicting the maximum column moment, plastic rotation and post-yield hardening parameters. The proposed formulation reasonably predicts the first-cycle envelope curves of built-up HBCs, improving prediction results based on ASCE 41 (2013) and NIST (2017).
Scrums play a major role in Rugby Union games, and are historically known as a showdown between the two packs of opposing teams, composed of their eight forwards players organized in a 3-4-1 ...configuration, respectively. We investigate scrum mechanics by working with professional male forward players from Racing 92, a high-level French Rugby club, and measuring the forces they apply on the French Rugby Federation instrumented scrum machine. Signal analysis reveals two major phases in the force production during a scrummaging effort: an impulsive engagement force, and then a force sustained for a few seconds. We experimentally compare individual performances of the engagement phase. We discuss the influence of the mass and the engagement speed of the players, and we introduce the model we are investigating to describe the individual impact on a scrum machine. We expect this model to be the elementary component of a collective model of a pack.
This study aimed to investigate the possible causes or conditions for the greater hardening or more hardened consistency of the plinthic feature, particularly in relation to forms and quantities of ...iron both in wet and dry conditions, taking into account that variations in the degree of consistency of these features are a phenomenon of great importance in the behavior of the soils of the Araguaia River floodplain, Brazil, due to its wide agricultural use. Soil features were collected at five positions in the profiles, where initial, central, and base plinthic horizons were detected. The separated samples of matrix, mottle, and plinthite were broken by the Instron apparatus and ground into powder. Then, chemical determinations were carried out by X-ray fluorescence (XRF), sulfuric acid attack (H2SO4), citrate-bicarbonate-dithionite (CBD), acid ammonium oxalate, and X-ray diffraction. The greater hardness of the plinthic features of the soils is directly related to the iron content in the oxidized form contained in its fine fraction and iron oxides are the elements responsible for promoting and maintaining the hardening of the features. The presence of the plinthic feature with the adequate hardness requirements was observed in the cases that presented a combination of the following factors: seasonality of the water regime; absolute Fed contents of at least 40.0 g kg−1 associated with a Fed/Fes ratio of at least 0.35; and Fes values equal to or >100 g kg−1 associated with a Fes/Fet ratio of at least 0.70. High Feo/Fed ratios, above 0.07, are indicative of more unstable features and, at the same time, with greater potential for hardening after drying.
•Soils with redoximorphic features subjected to anthropic use can harden irreversibly.•Iron oxides are responsible for the hardening of the redoximorphic features.•The goethite and hematite peaks showed a higher crystallinity of plinthite.•Fed ≥40 and Fes ≥ 100 g kg−1 are suitable feature hardness requirements.•Feo/Fed ratio above 0.07 indicates greater instability of plinthic features.
•Poisson effect increase significantly compression sensing of nanotube sensor.•Pre-compression is used to form nano-sized cracks in the sensor to affect sensing.•Sensor response is stable and linear ...during compression/relaxation cycles.•Sensor practical use is tested in slow as well as very fast pressure changes.
Poisson effect when a sensor made of multi-walled carbon nanotube network embedded in the elastic polyurethane was compressed in one direction and expanded in the other two directions perpendicular to the direction of compression several fold enhanced the sensing owing to nano-sized cracks of the network. The composite sensitivity was further multiplicatively enhanced by KMnO4 oxidation of carbon nanotubes. As an example of the composite use as a compression sensor, a pressure on the shoe sole was monitored as well as a ball bullet impact on the sensor.
The influence of pasteurization temperature and time of treatment on the flesh firmness and the evolution of microbial communities was studied for table olives Cv. Nocellara del Belice, packed in ...glass jars and processed with a tunnel pasteurizer. The experiment was first carried out on the laboratory level in order to select the optimal combination of pasteurization time/temperature so as to obtain the proper balance between the consistency of the pulp and the microbiological quality of the final product. Pasteurization at industrial scale was then carried out in a tunnel pasteurizer applying the treatment at 75 °C for 8 min in the thermal center of the jars. Besides flesh firmness and microbial evolutions, the pH, total titratable acidity (TTA) and color were evaluated for the table olives during storage at 6, 12 and 15 months from packing. The table olives showed a high stability and acceptable flesh firmness for the entire period under observation. Specifically, olive pulp texture decreased during the storage period, but the softening was most evident in the deeper layers of the pulp. The results indicated that the storage period should not exceed 6 months. Although the hygiene is preserved, after this period the firmness might not be acceptable to consumers.
Breast compression during mammographic examinations improves image quality and patient management. Several studies have been conducted to assess compression force variability among practitioners in ...order to establish compression guidelines. However, no such study has been conducted in Ghana. This study aims to investigate the compression force variability in mammography in Ghana.
This retrospective study used data gathered from 1071 screening and diagnostic mammography patients from January, 2018–December, 2019. Data were gathered by seven radiographers at three centers. Compression force, breast thickness and practitioners' years of work experience were recorded. Compression force variability among practitioners and the correlation between compression force and breast thickness were investigated.
Mean compression force values recorded for craniocaudal (CC) (17.2 daN) and mediolateral oblique (MLO) (18.2 daN), were within the recommended values used by western countries. Most of the mammograms performed – 80% – were within the National Health Service Breast Screening Programme (NHSBSP) range. However, 65% were above the Norwegian Breast Cancer Screening Programme (NBCSP) range. Compression forces varied significantly (p = 0.0001) among practitioners. Compression forces increased significantly (p = 0.0001) with the years of work experience. A weak negative correlation (r = −0.144) and a weak positive correlation (r = 0.142) were established between compression force and breast thickness for CC and MLO projections respectively.
This initial study confirmed that although wide variations in compression force exist among practitioners in Ghana, most practitioners used compression forces broadly within the range set by the NHSBSP. As no national guidelines for compression force currently exist in Ghana, provision of these may help to reduce the range of variations recorded.
Confirmation of variations in compression will guide future practice to minimize image quality disparities and improve quality of care.
Adherence to screening may indirectly help assess whether a prior screening examination deters women from returning for a subsequent examination. We investigated whether compression force and ...pressure in mammography were associated with re-attendance among prevalently screened women in the organized breast cancer screening program in Norway. Data on compression force (kg) and pressure (kPa) from women's first screening examination in the program (prevalent screening) and subsequent re-attendance were available for 31,225 women aged 50–68, screened during 2007–2013. Crude re-attendance rates and log-binomial regression models estimating the prevalence ratio of re-attendance were used to identify the association between compression force or pressure and re-attendance two-years later. Age and year at prevalent screening, county of residence, screening result (negative or false positive), breast volume, and breast density were included in analyses. Overall, 27,197 (87.1%) women re-attended the program. Re-attendance was highest for women who received a compression force of 10.0–13.9 kg (87.5%) or pressure of 9.0–17.9 kPa (87.8%) and lowest for those who received a compression force of <10.0 kg (85.0%) or pressure of <9.0 kPa (84.7%). The adjusted prevalence of re-attendance was 3% lower for women who received low compression force (<10.0 kg) and 2% lower for women who received low compression pressure (<9.0 kPa) relative to the reference groups (10.0–13.9 kg and 9.0–17.9 kPa, respectively). Future research related to re-attendance should also include information about women's experience of pain, anxiety and stress, as well as image quality.
•Compression force and pressure were associated with re-attendance in an organized breast cancer screening program.•Compression force of <10.0 kg and pressure of <9.0 kPa were associated with the lowest re-attendance.•Medium to high compression force and pressure were associated with the highest re-attendance.
Mechanical compression simulating orthodontic tooth movement in in vitro models induces pro-inflammatory cytokine expression in periodontal ligament (PDL) cells. Our previous work shows that TLR4 is ...involved in this process. Here, primary PDL cells are isolated and characterized to better understand the cell signaling downstream of key molecules involved in the process of sterile inflammation via TLR4. The TLR4 monoclonal blocking antibody significantly reverses the upregulation of phospho-AKT, caused by compressive force, to levels comparable to controls by inhibition of TLR4. Phospho-ERK and phospho-p38 are also modulated in the short term via TLR4. Additionally, moderate compressive forces of 2 g/cm2, a gold standard for static compressive mechanical stimulation, are not able to induce translocation of Nf-kB and phospho-ERK into the nucleus. Accordingly, we demonstrated for the first time that TLR4 is also one of the triggers for signal transduction under compressive force. The TLR4, one of the pattern recognition receptors, is involved through its specific molecular structures on damaged cells during mechanical stress. Our findings provide the basis for further research on TLR4 in the modulation of sterile inflammation during orthodontic therapy and periodontal remodeling.
Magnetic compression anastomosis (MCA) is a commonly used anastomosis method. MCA was widely used in tissues repair, gastroenterostomy, choledochoenterostomy, and so on. It is safer and more ...effective than stapler and manual surgical suturing. However, there are few detailed studies on the biomechanical characteristics and tissue transformation mechanisms of the anastomosis process. In this research, taking intestinal tissue as research object, we need to determine an optimal compressive force range to provide a biomechanical reference for the design of anastomats.
Magnets with different magnetic force groups (2.06, 3.21, 6.27, 13.3 and 19.2 N) were implanted into each dog to form intestinal tissue side-to-side anastomoses. Five dogs were euthanized on each of postoperative day 1, day 3, and day 7. Anastomoses were then harvested and compared with respect to postoperative complications, histology and tear-resistance load capacity (TRLC).
The TRLC of anastomotic tissue formed by magnets with different magnetic forces differed markedly, but with the tissue growth, the TRLC differences between groups were decreased. Histology of anastomotic tissue showed that, in the initial stage, the anastomoses compressed by 2.06-N magnets did not form effectively, while the leakage appeared in the anastomoses compressed by 19.2-N magnets, in the rest groups, with magnetic force increasing, severity of ischemia and necrosis of compressed tissue increased and healing speed of anastomotic tissue improved. In the late stage, the influence of magnetic force for anastomotic tissue was gradually diminished.
The magnetic force applied on the magnetic compression anastomats affects the necrosis speed of compressed tissue and the healing speed of anastomotic tissue. The optimal compressive force range for intestinal compression anastomosis is 6.27 N to 13.3 N, and the actual optimal compression pressure is 79.8 kPa - 169 kPa.
Magnetic compression anastomosis (MCA) is a commonly used anastomosis method. MCA was widely used in tissues repair, gastroenterostomy, choledochoenterostomy, and so on. It is safer and more effective than stapler and manual surgical suturing. However, there are few detailed studies on the biomechanical characteristics and tissue transformation mechanisms of the anastomosis process. In this research, taking intestinal tissue as research object, we need to determine an optimal compressive force range to provide a biomechanical reference for the design of anastomats.
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