Peak activation of lower limb musculature during high flexion kneeling and transitional movements

Few studies have measured lower limb muscle activation during high knee flexion or investigated the effects of occupational safety footwear. Therefore, our understanding of injury and disease mechanisms, such as knee osteoarthritis, is limited for these high-risk postures. Peak activation was assessed in eight bilateral lower limb muscles for twelve male participants, while shod or barefoot. Transitions between standing and kneeling had peak quadriceps and tibialis anterior (TA) activations above 50% MVC. Static kneeling and simulated tasks performed when kneeling had peak TA activity above 15% MVC but below 10% MVC for remaining muscles. In three cases, peak muscle activity was significantly higher (mean 8.9% MVC) when shod. However, net compressive knee joint forces may not be significantly increased when shod. EMG should be used as a modelling input when estimating joint contact forces for these postures, considering the activation levels in the hamstrings and quadriceps muscles during transitions.

Practitioner Summary: Kneeling transitional movements are used in activities of daily living and work but are linked to increased knee osteoarthritis risk. We found peak EMG activity of some lower limb muscles to be over 70% MVC during transitions and minimal influence of wearing safety footwear.     

The effects of a simulated occupational kneeling exposure on squat mechanics and knee joint load during gait

Occupational kneeling is associated with an increased risk for tibiofemoral knee osteoarthritis. Forces on the knee in the kneeling posture, as well as the greater incidence of meniscus tears among workers, likely contribute to the increased risk. We hypothesise that an additional mechanism may contribute – altered neuromuscular control due to prolonged high knee flexion. Forty participants (20 male, 20 female) completed an evaluation of gait and squatting before, immediately following, and 30 min following a 30 min simulated occupational kneeling exposure. An increase in the peak external knee adduction moment and a delay in vastus medialis activation onset during walking were observed post-kneeling, as well as increased frontal plane knee motion during squatting. This was the first investigation to find changes in high flexion transitions as a result of kneeling. Greater frontal plane knee motion may increase the risk for meniscal tears, and subsequently, knee osteoarthritis.

Practitioner Summary: A 30 min simulated occupational kneeling exposure resulted in small but significant gait changes. The greatest effect was on frontal plane knee movement during squatting, which is especially relevant to occupations requiring frequent kneeling/squatting. This increased motion may indicate an increased risk of injury, which supports a link to knee osteoarthritis.     

A new preference scale mcdm method based on interval-valued intuitionistic fuzzy sets and the analytic hierarchy process

The intuitionistic fuzzy analytic hierarchy process (IF-AHP), in which intuitionistic fuzzy numbers are utilized in defining decision makers’ linguistic judgment, has been used to solve various multi-criteria decision-making problems. Previous theories have suggested that interval-valued intuitionistic fuzzy numbers (IVIFN) with hesitation degree can act as alternative fuzzy numbers that can handle vagueness and uncertainty. This paper proposes a new preference scale in the framework of the interval-valued intuitionistic fuzzy analytic hierarchy process (IVIF-AHP). The comparison matrix judgment is expressed in IVIFN with degree of hesitation. The proposed new preference scale concurrently considers the membership function, the non-membership function and the degree of hesitation of IVIFN. To define the weight entropy of the aggregated matrix of IVIFN, a modified interval-valued intuitionistic fuzzy weighted averaging is proposed, by considering the interval number of the hesitation degree. Three multi-criteria decision-making problems are used to test the proposed method. A comparison of the results is also presented to check the feasibility of the proposed method. It is shown that the ranking order of the proposed method is slightly different from that of the other two methods because of the inclusion of the hesitation degree in defining the preference scale.     

Electrochemical behavior of a new <Emphasis Type="Italic">s</Emphasis>-triazine-based dendrimer

The electrochemical behavior of a new G-2-s-triazine-based dendrimer, 2,4,6-tris-{4-{4,6-bis-{4-{4,6-bis-[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-s-triazin-2-yl}-piperazin-1-yl}-s-triazine, (I), was studied in dimethylsulfoxide solution by cyclic voltammetry, on platinum and graphite electrodes. The electrochemical properties of I were compared with that of one of its precursor, N-{4,6-bis{4-{4,6-bis[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-triazin-2-yl}-piperazine), (II), together with that of the starting material, (1S,2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol (“p-nitrophenylserinol”), (III).     

Extreme scale computing: Modeling the impact of system noise in multi-core clustered systems

System noise or Jitter is the activity of hardware, firmware, operating system, runtime system, and management software events. It is shown to disproportionately impact application performance in current generation large-scale clustered systems running general-purpose operating systems (GPOS). Jitter mitigation techniques such as co-scheduling jitter events across operating systems improve application performance but their effectiveness on future petascale systems is unknown. To understand if existing jitter mitigation solutions enable scalable petascale performance, we construct two complementary jitter models based on detailed analysis of system noise from the nodes of a large-scale system running a GPOS. We validate these two models using experimental data from a system consisting of 256 GPOS instances with 8192 CPUs. Based on our models, we project a minimum slowdown of 1.8%, 4.1%, and 6.5% for applications executing on a similar one petaflop system running 1024 GPOS instances and having global synchronization operations once every 100 ms, 10 ms, and 1 ms, respectively. Our projections indicate that–although existing mitigation solutions enable scalable petascale performance–additional techniques are required to contain the impact of jitter on multi-petaflop systems, especially for tightly synchronized applications.     

Evaluation of natural hog casings modified by surfactant solutions combined with lactic acid by response surface methodology

The effects of soy lecithin concentrations (X₁, 1:25–1:30), soy oil concentrations (X₂, 0%–2.5%), residence time for surfactant solutions (X₃, 60–90 min) and lactic acid concentrations (X₄, 18–21 ml/kg) on technological properties of hog casings were evaluated by response surface methodology (RSM). The burst pressure, maximum rupture force, and elongation of both uncooked treated casings (UTC) and cooked treated casings (CTC) were determined. The histological structures of UTC and CTC were observed by light microscopy and transmission electron microscope and images illustrated that casings became more porous after treatments. Polynomial regression models on burst pressure of UTC (P < 0.05) and CTC (P < 0.05), maximum rupture force of UTC (P < 0.01) and elongation of CTC (P < 0.01) were established. Sausage was made using modified casing with the best resistance of burst pressure or rupture force. Bursting during immersion vacuum cooling did not happen to sausages made from these modified casings.     

Study on Lake Izvorul Muntelui rehabilitation

In the actual economical and ecological context the rehabilitation of aquatic ecosystems represents one of the most important concerns all over the world. The physical, chemical and biological processes that take place inside a lake are very complex. A simple analysis of the field data is not enough. Even if those dates offers an appreciation of the global functioning of the ecosystem under the influence of certain factors, it does not allow to predict the system evolution, the optimization of the water arrangement, in order to respect and to assure the water quality criteria or to propose solutions for diminishing the lakes eutrophication.In the recent years, Lake Izvorul Muntelui, which is the largest artificial lake on the interior waters of Romania, experienced eutrophication problems. This paper analyzes the apparition condition, its effects onto water quality in the lake and the solutions for the rehabilitation of the ecosystem. Since systematic measured data are not available for this ecosystem, the mathematical modelling it is used.The simulation is done by considering the ecosystem dynamic and the stipulation of the spatial and temporal variation domains for the natural processes to appear and act onto perturbation factors to modify the ecological succession.Thus, different scenarios will be created allowing us to offer solutions for the eutrophication phenomenon and, in the same time, to identify solutions for the rehabilitation of the Izvorul Muntelui Lake.     

Electrodeposited Zn–TiO<Subscript>2</Subscript> nanocomposite coatings and their corrosion behavior

The present paper aims to investigate the electrodeposition on steel substrate and the corrosion behavior of Zn–TiO₂ nanocomposite coatings. Zn–TiO₂ composite coatings were electrodeposited on OL 37 steel from an electrolyte containing ZnCl₂, KCl, HBO₃ (pH 5.7) brightening agents and dispersed nanosized TiO₂. Corrosion measurements were performed in 0.2 g L⁻¹ (NH₄)₂SO₄ solution (pH 3) by using electrochemical methods (open-circuit potential measurements, polarization curves, electrochemical impedance spectroscopy). The results of electrochemical measurements were corroborated with those obtained by using non-electrochemical methods (X-ray diffraction, atomic force microscopy and scanning electron microscopy). The results indicate that the composite coatings exhibit higher corrosion resistance as compared to pure Zn coatings and a non-linear dependence of their polarization resistance on TiO₂ concentration in the plating bath was found. The importance of TiO₂ nature and concentration regarding the properties of the composite coatings was demonstrated.     

A systematic review of domain analysis tools

The domain analysis process is used to identify and document common and variable characteristics of systems in a specific domain. In order to achieve an effective result, it is necessary to collect, organize and analyze several sources of information about different applications in this domain. Consequently, this process involves distinct phases and activities and also needs to identify which artifacts, arising from these activities, have to be traceable and consistent. In this context, performing a domain analysis process without tool support increases the risks of failure, but the used tool should support the complete process and not just a part of it. This article presents a systematic review of domain analysis tools that aims at finding out how the available tools offer support to the process. As a result, the review identified that these tools are usually focused on supporting only one process and there are still gaps in the complete process support. Furthermore, the results can provide insights for new research in the domain engineering area for investigating and defining new tools, and the study also aids in the identification of companies’ needs for a domain analysis tool.     

Carbonate binders by “cold sintering” of calcium carbonate

The solubility of calcium carbonate (limestone) particles depends on the amount of CO₂ dissolved in the water, which is a function of temperature and the pressure of CO₂ that is in equilibrium with water. At a constant temperature, increasing CO₂ pressure increases the solubility of CaCO₃, and decreasing CO₂ pressure favours the crystallisation of CaCO₃. This dissolution–crystallisation behaviour of CaCO₃ can be used in the development of carbonate binders—a process called “cold sintering”—of limestone. This paper examines the effect of a range of parameters on the cold sintering process of limestone powder. The parameters studied are CO₂ gas pressure (atmospheric, 10 atm and 35 atm), exposure time (0–90 min), post-compaction pressure (10 and 15 MPa) and compact pressing time (10–60 min). The water/limestone powder ratio was kept constant at 0.2 (by weight). The compressive strength of the limestone compacts was used as a measure of the efficiency of the carbonate binder formation process, and scanning electron microscopy was used to study the microstructural developments. The results show that carbonate binders can be produced by cold sintering of limestone powder. Exposure of limestone compacts to high CO₂ pressure followed by post-compaction at high mechanical pressure, enhances the strength of the compact. From the microstructural data, it is evident that newly formed calcium carbonate crystal growths are responsible for the strength improvements observed. The amount of water that is used in the limestone powder mixture is one factor that controls the quantity of the cementing phase. Future work has to be focussed on the application of methods to further increase the solubility of calcium carbonate, as the amount of calcium carbonate available for recrystallisation is important in producing a strong binder.