Direct Linear Relation Research Articles

Development of a mandrel indentation test to evaluate surface hardness of dimensional building stones and comparison to Vickers hardness

The present research introduces a new method namely mandrel indentation test (MIT) to evaluate surface hardness of rocks and building stones and comparing its results with the Vickers hardness test results. For performing the test, first, its apparatus was designed and built from hard and rigid steel in a turning workshop. Then, it was used on 50 common carbonate building stones including 30 limestones and 20 travertines in the laboratory. Also, surface hardness of the stones was evaluated by the Vickers hardness test. The values of mandrel indentation hardness (MIH) for the building stones were obtained between 31.75 and 113.85 kgf/mm2, and the values of Vickers hardness (HV) were obtained between 286.11 and 1361.98 kgf/mm2. The developed correlation analysis results together with the obtained Pearson, Spearman, and Kendall correlation coefficients indicated that the values of the surface hardness resulted from this approach is strongly correlated to the values of the Vickers test by a direct linear relation. The stablished simple regression analysis has confirmed the results of the correlation analysis by a determination coefficient of 0.841. Five well‐known statistical indexes were used to assess accuracy performance degree of the developed regression model. As an important finding of the research, the introduced approach has high potential and accuracy for evaluating surface hardness of the studied building stones. Finally, a classification system was proposed to classify different building stones based on their surface hardness. Based on the classification, the studied building stones are classified as very soft to moderately hard with low hardness ratio.

CORRELATION OF THYROID PROFILE WITH SEVERITY OF CHRONIC KIDNEY DISEASE :A TERTIARY CARE CENTER STUDY

Background: CKD is associated with a higher prevalence of primary hypothyroidism both overt and subclinical, but not with hyperthyroidism. Prevalence of primary hypothyroidism, mainly in the subclinical form, increases as glomerular ltration rate (GFR) decreases. Materials and methods: The present study is a crosssectional study conducted among 350 patient admitted in medicine department, Chirayu medical college and hospital ,Bhopal from a period of 1st February 2021to 31July 2022. In the present study, patient who diagnosed as chronic kidney diseases were included and their thyroid prole were done by CLIA (chemiluminescence immunoassay) method using MAGLUMI 2000 machine. Aims and objective: The aim of the present study is to assess thyroid dysfunction in chronic kidney disease patients and the correlation between thyroid dysfunction with the severity of renal diseases. Result and conclusion: In the present study, there is signicant correlation between thyroid dysfunction with progression of CKD and there is a direct linear relation with eGFR and T3 ,T4 level in the present study

Stability of Wheat Genotypes by AMMI and Yield Evaluated under Peninsular Zone of India

Background: Efficient estimation of main and interaction effects under multi environment trials had been carried out by AMMI. Studies with low proportion of the variance explained by first interaction principal component IPCA1 under AMMI analysis had been reported biased interpretation for the stability of the genotypes.Methods: Weighted Average of Absolute scores (WAASB), quantitative stability measure had been recommended for selection of productive genotypes with broad adaptation. The selection of promising genotypes had been assisted by use of superiority index (WAASBY) that considered simultaneous use of yield and stability by allowing variable weighting mechanism for yield and stability.Result: Wheat GW509 and HI1633 genotypes had been identified by stability measure WAASB for the first year. While Superiority index considered stability and high yield settled for HI1633 and Raj4083 genotypes. Analytic measures of adaptability PRVG and MHPRVG observed suitability of HI1633 and Raj 4083. SI expressed positive linear behaviour with yield, MHPRVG and PRVG measures. While stability measure WAASB maintained moderate negative correlation with yield, SI, MHPRVG and PRVG. Wheat genotypes HI1633, HI1641 and HI1646 identified by stability measure for the next year of study. Superiority index selected HI1641, HI1633 and MACS6752 genotypes. SI expressed direct linear relation with yield, MHPRVG and PRVG. Stability measure exhibited indirect relationships with SI, MHPRVG, PRVG and yield Wheat genotypes HI1633, Raj 4083 for first year and HI1641, MACS6752 for the second year of study.

Functional assessment of myocardial ischaemia by intracoronary ECG

IntroductionIn patients with chronic coronary syndrome, percutaneous coronary intervention targets haemodynamically significant stenoses, that is, those thought to cause ischaemia. Intracoronary ECG (icECG) detects ischaemia directly where it occurs. Thus,...

Influence of Artificial Aging on Mechanical Properties and High Stress Abrasive Wear Behaviour of Al–Mg–Si Alloy

The present study evaluated hardness, tensile properties and two-body abrasive wear behaviour of Al–Mg–Si alloy specimens artificially aged at 448 K for different durations ranging from 0.5 to 504 h. In addition to the measurements of Vickers hardness and tensile properties, wear tests of differently aged alloys were conducted against SiC abrasive paper of 220 grit size under normal load of 9.81 N with the help of a pin-on-disc tribometer. Abrasive wear characteristics were assessed in terms of measurements of specific wear rate and roughness of the abraded surfaces. These were substantiated via examinations of worn surfaces, collected wear debris and subsurfaces of worn specimens to comprehend the micro-mechanisms of abrasion. The abrasive wear performance varied significantly with the duration of artificial aging and the lowest specific wear rate as well as roughness of the abraded surfaces corresponded to the peak-aged condition. An attempt was also made to correlate mechanical properties and tribological performance. It was found that the specific wear rate exhibited direct linear relation with the strain hardening exponent, and inverse linear relationships with hardness, yield strength and strength coefficient. Microplowing, microcutting and microcracking were identified as mechanisms of abrasion; the extents of these processes were found to be governed by the state of aging that determined the mechanical properties.

Investigation into the Role of Surface Modification of Cellulose Nanocrystals with Succinic Anhydride in Dye Removal

Herein, the effect of surface modification of cellulose nanocrystals (CNC) on the sorption of dyes from waste textile effluent (methylene blue as a model) was achieved. The esterification of the isolated CNC from wood sawdust by acid hydrolysis was performed through melting with succinic anhydride (SA). At using 1:3–1:9 as the feeding ratios of CNC to SA, the succinylated CNC (CNC-SA) was obtained with degree of substitution of 1.6–2.2 and carboxylic content of 286.8–381.7 mmol/kg. Both of diameter size and zeta potential of the prepared CNC-SA were gradually enlarged by increasing the reactant feed ratio, indicating the successful modification of CNC surface with highly stable particles via increasing the negative charges on the outer surface. FTIR and XRD affirmed the change in the chemical structure as well as crystallinity of CNC after succinylation reaction. The prepared succinylated CNC was applied in the removal of methylene blue (MB) dye and the data showed that the sorption capacity is a direct proportional linear relation with the contents of carboxylic group. Within 120 min contact time, the sorption capacity was enlarged from 64.1 mg/g for CNC to 84.1 mg/g for CNC-SA3. The sorption data was fitted well to the first order kinetic model. Due to the esterification, the rate of sorption reaction is accelerated by double factor. These findings will maximize the benefit of esterified CNC in water treatment.

Impact of urbanization on climate change and geographical analysis of physical land use land cover variation using RS-GIS.

<p>This study focuses on the impact of climate change on rainfall-runoff pattern, and to assess the surface runoff and groundwater recharge potential from the intensified rainfall for the effective management of surface and groundwater resources in Tirunelveli city. The rainfall contribution is consistent, dependent, maximum and intensified during the month of November followed by October and December. The intensified rainfall in these months causes a temperature decrease and the climate becomes more and more colder than ever. The indices SPI and DI clear show that there is a change in climatic pattern. Landuse Landcover (LULC) analysis shows that the residential area and mining area is on the increasing trend, Village area is slightly increasing, agricultural area and dense scrub area is on the decreasing trend. The present capacity of the storage tanks available in Tirunelveli city is less than the maximum runoff generated during the month of November. The increase in residential area in LULC reflects the direct linear relation with the population increase of the city. The impact of urbanization leads to LULC change with the loss of agricultural land and water bodies.</p>

Relation between functional connectivity and disability in multiple sclerosis: a non-linear model.

To characterize the relation between brain functional connectivity and disability in patients with multiple sclerosis; to investigate the existence of critical values of both disability and functional connectivity corresponding to exhaustion of functional adaptive mechanisms. Hundred-and-nineteen patients with no-to-severe disability and 42 healthy subjects were studied via 3T resting state functional MRI. Out of 116 regions extracted from Automated Anatomical Labeling atlas, pairs of regions whose functional connectivity correlated with Expanded Disability Status Score were identified. In patients, mathematical modeling was applied to find the best models describing Expanded-Disability-Status-Score vs structural or functional measures. Functional vs structural models intersecting points were identified. Disability had direct linear relation with lesion load (r = 0.40, p < 5E-6), inverse of thalamic volume (r = 0.31 p < 1E-3) and functional connectivity in bi-frontal pairs of regions (r > 0.40, p < 0.04), while being non-linearly associated with functional connectivity in cerebello-temporal and cerebello-frontal pairs of regions (F > 1.73, p < 0.02). Structural vs functional models intersecting points corresponded to Expanded Disability Status Score of 3.0. 85% of patients scoring more than 3.0 showed functional connectivity in cerebello-temporal and cerebello-frontal pairs of regions below confidence intervals (z = [2.28-2.88] 95% CI) measured in healthy subjects. Functional brain connectivity changes may represent mechanisms of adaptation to structural damage and inflammation and may be not always clinically beneficial. Functional connectivity decreases in comparison with structural measure at Expanded Disability Status Score greater than 3.0, which may be critical and indicate exhaustion of compensatory mechanisms.

Realization of Direct Linear Relation Between Control Voltage and Resonance Frequency of the LC Voltage Controlled Oscillator

Realization of Direct Linear Relation Between Control Voltage and Resonance Frequency of the LC Voltage Controlled Oscillator

Accretion-driven turbulence in filaments – I. Non-gravitational accretion

We study accretion driven turbulence for different inflow velocities in star forming filaments using the code ramses. Filaments are rarely isolated objects and their gravitational potential will lead to radially dominated accretion. In the non-gravitational case, accretion by itself can already provoke non-isotropic, radially dominated turbulent motions responsible for the complex structure and non-thermal line widths observed in filaments. We find that there is a direct linear relation between the absolute value of the total density weighted velocity dispersion and the infall velocity. The turbulent velocity dispersion in the filaments is independent of sound speed or any net flow along the filament. We show that the density weighted velocity dispersion acts as an additional pressure term supporting the filament in hydrostatic equilibrium. Comparing to observations, we find that the projected non-thermal line width variation is generally subsonic independent of inflow velocity.

Exploring relations between EMG and biomechanical data recorded during a golf swing

A novel technique to explore relations between EMG and biomechanical data is presented.Statistically significant relations between EMG and biomechanical data were revealed.High prediction accuracy of peak angular velocity of thorax and pelvis was obtained.Insights concerning coordination of human body parts during a golf swing were obtained. Exploring relations between patterns of peak rotational speed of thorax, pelvis and arm, and patterns of EMG signals recorded from eight muscle regions of forearms and shoulders during the golf swing is the main objective of this article. The linear canonical correlation analysis, allowing studying relations between sets of variables, was the main technique applied. To get deeper insights, linear and nonlinear random forests-based prediction models relating a single output variable, e.g. a thorax peak rotational speed, with a set of input variables, e.g. an average intensity of EMG signals were used.The experimental investigations using data from 16 golfers revealed statistically significant relations between sets of input and output variables. A strong direct linear relation was observed between linear combinations of EMG averages and peak rotational speeds. The coefficient of determination values R2=0.958 and R2=0.943 obtained on unseen data by the random forest models designed to predict peak rotational speed of thorax and pelvis, indicate high modelling accuracy. However, predictions of peak rotational speed of arm were less accurate. This was expected, since peak rotational speed of arm played a minor role in the linear combination of peak speeds. The most important muscles to predict peak rotational speed of the body parts were identified. The investigations have shown that the canonical correlation analysis is a promising tool for studying relations between sets of biomechanical and EMG data. Better understanding of these relations will lead to guidelines concerning muscle engagement and coordination of thorax, pelvis and arms during a golf swing and will help golf coaches in providing substantiated advices.

Comparison between Diastolic Subendocardial Tissue Pressures Measured Directly or Calculated from Pressure-Flow Relations

Changes in intramyocardial tissue pressure modulate the relationship between coronary pressure and flow during the cardiac cycle. The present study compared the relation between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero flow in anesthetized dogs after modulation of either coronary sinus (i.e. Fogarty catheter) or left ventricular intracavity (i.e. volume loading) pressure. Experiments were conducted in anesthetized, instrumented dogs; coronary pressure flow relations were constructed during pharmacologic vasodilatation and intramyocardial tissue pressure was measured using micromanometer pressure sensors. Elevated coronary sinus pressures did not affect subendocardial pressure-flow relations signifying that diastolic tissue pressure within this layer is the effective coronary back pressure. Higher left ventricular intracavity pressure did not affect either diastolic subendocardial tissue pressure or pressure flow relations within this layer. Results show a direct linear relation (y = 1.106x - 0.652; r2 = 0.59. P = 0.001) between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero-flow over a wide range of pressures after either LV systemic or coronary sinus pressure modulation. Knowledge of back pressure in the subendocardium is useful for the evaluation of efficacy of cardiac interventions on myocardial perfusion particularly at the level of the microcirculation.

Colorimetric disposable paper coated with ZnO@ZnS core-shell nanoparticles for detection of copper ions in aqueous solutions.

In this study, we have proposed a new nanoparticle-containing test paper sensor that could be used as an inexpensive, easy-to-use, portable, and highly selective sensor to detect Cu(2+) ions in aqueous solutions. This disposable paper sensor is based on ZnO@ZnS core-shell nanoparticles. The core-shell nanoparticles were synthesized using a chemical method and then they were used for coating the paper. The synthesis of the ZnO@ZnS core-shell nanoparticles was performed at a temperature as low as 60 °C, and so far this is the lowest temperature for the synthesis of such core-shell nanoparticles. The sensitivity of the paper sensor was investigated for different Cu(2+) ion concentrations in aqueous solutions and the results show a direct linear relation between the Cu(2+) ions concentration and the color intensity of the paper sensor with a visual detection limit as low as 15 μM (∼0.96 ppm). Testing the present paper sensor on real river turbulent water shows a maximum 5% relative error for determining the Cu(2+) ions concentration, which confirms that the presented paper sensor can successfully be used efficiently for detection in complex solutions with high selectivity. Photographs of the paper sensor taken using a regular digital camera were transferred to a computer and analyzed by ImageJ Photoshop software. This finding demonstrates the potential of the present disposable paper sensor for the development of a portable, accurate, and selective heavy metal detection technology.

Expression of blood serum proteins and lymphocyte differentiation clusters after chronic occupational exposure to ionizing radiation.

This study aimed to assess effects of chronic occupational exposure on immune status in Mayak workers chronically exposed to ionizing radiation (IR). The study cohort consists of 77 workers occupationally exposed to external gamma-rays at total dose from 0.5 to 3.0 Gy (14 individuals) and workers with combined exposure (external gamma-rays at total dose range 0.7-5.1 Gy and internal alpha-radiation from incorporated plutonium with a body burden of 0.3-16.4 kBq). The control group consists of 43 age- and sex-matched individuals who never were exposed to IR, never involved in any cleanup operations following radiation accidents and never resided at contaminated areas. Enzyme-linked immunoassay and flow cytometry were used to determine the relative concentration of lymphocytes and proteins. The concentrations of T-lymphocytes, interleukin-8 and immunoglobulins G were decreased in external gamma-exposed workers relative to control. Relative concentrations of NKT-lymphocytes, concentrations of transforming growth factor-β, interferon gamma, immunoglobulins A, immunoglobulins M and matrix proteinase-9 were higher in this group as compared with control. Relative concentrations of T-lymphocytes and concentration of interleukin-8 were decreased, while both the relative and absolute concentration of natural killers, concentration of immunoglobulins A and M and matrix proteinase-9 were increased in workers with combined exposure as compared to control. An inverse linear relation was revealed between absolute concentration of T-lymphocytes, relative and absolute concentration of T-helpers cells, concentration of interferon gamma and total absorbed dose from external gamma-rays in exposed workers. For workers with incorporated plutonium, there was an inverse linear relation of absolute concentration of T-helpers as well as direct linear relation of relative concentration of NKT-lymphocytes to total absorbed red bone marrow dose from internal alpha-radiation. In all, chronic occupational IR exposure of workers induced a depletion of immune cells in peripheral blood of the individuals involved.

Pruning of Buttress Roots and Stability Changes of Red Maple (Acer rubrum)

The purpose of this study was to evaluate the effects of buttress root pruning on tree stability and to compare different methods of correlating various root parameters to force levels. Ten plantation-grown Acer rubrum (red maple) trees were pulled to an angle of one degree from vertical with measured force, then roots were individually severed near the trunk and the pull tests were repeated until roots had been pruned from 50% of the circumference. Test trees had 6 to 10 buttress roots. There was a nearly direct linear relation between the number of roots removed and the force applied. When comparing four assessment methods to determine pull force change associated with root pruning, the method that had the greatest amount of variability explained by the regression was the comparison of the cross-sectional area of roots cut to the force. However, relating the percentage of buttress roots cut to the force provided only slightly less accurate information, and was more easily collected prior to tree removal.

M(II) transfer across a liquid-liquid microinterface facilitated by a complex formation with 8-Hydroxyquinoline: Application to quantification of Pb(II), Cd(II) and Zn(II) alone or in mixture in effluents

For the first time, the assisted transfer of Pb(II) across a water/1,2-Dichloroethane (DCE) microinterface was investigated in the presence of 8-Hydroxyquinoline (named also oxine or 8-HQ) in the organic phase. A monocharged complex was formed in the aqueous phase and then transferred in the organic phase. A good relationship was obtained between currents and Pb(II) concentrations in the 10−4 to 5 10−3M range and 10−5 to 6 10−5M range using cyclic voltammetry and square wave voltammetry respectively. In presence of other heavy metals such as Cd(II) and Zn(II), only one electrochemical process is observed regardless of the mixture. Moreover, stationary currents increase in direct linear relation with the sum of M(II) concentrations added in water, allowing an overall detection of heavy metals. This result indicates that this method can be very interesting for monitoring all toxic metals in effluents. The limit of detection was found equal to 0.2ppm for lead. This value allows us to reach levels significant for industrial effluents, in comparison to the limits fixed by the French ministry of ecology for lead, cadmium and zinc to 0.5ppm, 0.2ppm and 2.0ppm respectively. This study highlights the real interest of devices based on a liquid-liquid microinterface.

Aggressive Blood Pressure Lowering Is Dangerous: The J-Curve

Blood pressure (BP) is poorly controlled in the population, a phenomenon with adverse prognostic impact.1 However, a more aggressive approach toward BP lowering has been tempered over the last 2 to 3 decades by some reports suggesting a paradoxical increase in morbidity and mortality associated with an excessive reduction in BP, the so-called J-shaped curve hypothesis. Many investigations addressed this issue, and some excellent reviews discussed strengths and limitations of these studies in detail.2–5 We conducted an updated critical review of the most relevant studies and meta-analysis from our and other groups. We recognize that there is some evidence that a diastolic BP target <80 mm Hg,6 or an achieved diastolic BP <70 mm Hg,7 might be associated with an increased risk of myocardial infarction6 (MI) or total cardiovascular events7 in hypertensive patients with established coronary artery disease (CAD). However, with the possible exception of hypertensive patients with CAD, there are no convincing data behind the conclusion that an aggressive reduction of BP could be a direct cause of adverse outcome. Several studies that reported a J-shaped association between achieved BP and outcome have methodological limitations.2–5 In particular, several clinical conditions including, but not limited to, heart failure, previous MI, and cancer might have been the dominant and direct cause of adverse outcome in these patients, antihypertensive treatment being thus a sort of innocent bystander. As an implication of this line of thinking, dangerous would not be the excessive reduction in BP but rather the excessively low BP. The difference is not trivial. In subjects with or without risk factors, but free from overt cardiovascular disease, the log-linear relation between BP and rate of mortality from CAD or stroke appears to begin at values around 115/75 mm Hg, without …

An ascorbic acid amperometric sensor using over-oxidized polypyrrole and palladium nanoparticles composites

We constructed a highly responsive ascorbic acid (AA) sensor utilizing over-oxidized polypyrrole (OPPy) and Palladium nanoparticles (PdNPs) composites (OPPy–PdNPs). In the presence of PdNPs, polypyrrole (PPy) was coated on a gold (Au) electrode through cyclic voltammetry (CV) and over-oxidized at a fixed potential in NaOH solution. The PdNPs were characterized using ultraviolet–visible (UV–vis) spectrum and transmission electron microscopy (TEM). The surface of OPPy–PdNPs on the Au electrode was investigated using field-emission scanning electron microscopy (FE-SEM). Results revealed that the OPPy–PdNPs-modified Au electrode (OPPy–PdNPs/Au) has the capacity to catalyze the oxidation of AA by lowering its oxidation potential to 0V. The OPPy–PdNPs/Au electrode exhibited 2 different linear concentration ranges. In the low concentration range (1–520μM), OPPy–PdNPs/Au exhibited a direct linear relation with current responses and had high sensitivity (570μAmM−1cm−2) and a high correlation coefficient (0.995). In contrast, in the higher concentration range (120–1600μM), the relationship between current responses and concentration of AA can be represented by a two-parameter sigmoidal equation. In addition, the sensor exhibited a short response time (less than 2s) and a very low limit of detection of 1μM. The electrochemical AA sensor constructed in this study was simple, inexpensive, reproducible, sensitive, and resistant to interference. Thus, the proposed sensor has great potential for detecting AA in complex biosystems and can be applied in various fields, particularly neuroscience.

Analysis of electrical and mechanical left atrial properties in patients with persistent atrial fibrillation

The study of left atrial (LA) mechanical function during atrial fibrillation (AFib) can provide valuable information, particularly if such profiling is related to the cavity electrical substrate and conveys prognostic information. To assess if there is any relation between LA mechanical and electrical asynchrony and if such evaluation can be of interest in stratifying AFib patients. 50 patients with persistent AFib who underwent electrical cardioversion (CV) were evaluated with pre-CV atrial electrograms (AEGs). Electrical asynchrony was classified according to Wells' patterns of AEGs, ranging from most organized (I) to most dispersed (III) one. LA mechanical asynchrony was addressed by transthoracic 2D-speckle-tracking echo and quantified according to time-to-peak standard deviation (TP-SD) of wall strains and their peak values (PS) before CV, after 24h, at 1month. Pre-CV a linear, inverse relation between TP-SD and PS (p<0.001) and a direct linear relation between TP-SD and Wells' classes (p=0.04) were observed. With sinus rhythm TP-SD decreased (p=0.023) and PS increased (p<0.001), suggesting improved LA mechanical milieu. A multivariate analysis, testing the effects of baseline variables in predicting post-CV recurrence of AFib, revealed that amount of TP-SD variation pre/24h post-CV was the only independent predictor at 6months (p=0.046). Speckle tracking-derived LA parameters can describe LA wall forces during AFib, categorizing the asynchronous mechanistic profile of AFib that correlates with the degree of the dispersed LA electrical activity. The amount of changes in LA mechanical asynchrony pre/post-CV seems to have prognostic relevance in predicting SR maintenance.

Effect of Curvature and Thickness of Aluminum Shells on the Energy Absorption in Low Velocity Impact

The objective of this study is to investigate the behavior of Aluminum shells AA5083-H116 under low energy impact and the effects of curvature and thickness were assessed under different impact velocities (5.6, 7.5, 9.5, 11.5 m/s). LS-DYNA software was used to evaluate the amount of absorbed energy by the Aluminum shell during impact under different curvature parameter c. The results showed that the amount of absorbed energy incereases with increasing curvature in a linear relationship which make it possible to predict the amount of absorbed energy for this aluminum alloy under different impact energy. Aslo, the amount of absorbed energy has a direct linear relation with the rise of impact energy. The slopes of curves for absorbed energy with respect to the imapct energy are similar for all curvatures. Shell thickness has inverse effect on the amount of absorbed energy and the relation shows similar ternds with diffrent curvatures. However thick shells show significant increase in maximum force and better stability in the dynamic behavior with less fluctuations in the impact force as the cuvature increases.