Reduction In Specimens Research Articles

Experimental Study on the Strength Deterioration and Mechanism of Stabilized River Silt Reinforced with Cement and Alginate Fibers.

River silt deposited by water in coastal areas is unsuitable for engineering construction. Thus, the in situ stabilization treatment of river silt as the bearing layer has been an important research area in geotechnical engineering. The strength degradation behavior and mechanism of stabilized river silt reinforced with cement and alginate fibers (AFCS) in different engineering environments are crucial for engineering applications. Therefore, freeze-thaw (F-T) cycle tests, wetting-drying (W-D) cycle tests, water immersion tests and seawater erosion tests were conducted to explore the strength attenuation of stabilized river silt reinforced with the same cement content (9% by wet weight) and different fiber contents (0%, 0.3%, 0.6% and 0.9% by weight of wet soil) and fiber lengths (3 mm, 6 mm and 9 mm). The reinforcement and damage mechanism of AFCS was analyzed by scanning electron microscopy (SEM) imaging. The results indicate that the strength of AFCS was improved from 84% to 180% at 15 F-T cycle tests, and the strength of AFCS was improved by 26% and 40% at 30 W-D cycles, which showed better stability and excellent characteristics owing to the hygroscopic characteristics of alginate fiber arousing the release of calcium and magnesium ions within the alginate. Also, the strength attenuation of AFCS was reduced with the increase in the length and content of alginate fibers. Further, the strength of specimens in the freshwater environment was higher than that in the seawater environment at the same fiber content, and the softening coefficient of AFCS in the freshwater environment was above 0.85, indicating that the AFCS had good water stability. The optimal fiber content was found to be 0.6% based on the unconfined compressive strength (UCS) reduction in specimens cured in seawater and a freshwater environment. And the strength of AFCS was improved by about 10% compared with that of cement-stabilized soil (CS) in a seawater environment. A stable spatial network structure inside the soil was formed, in which the reinforcing effect of fibers was affected by mechanical connection, friction and interfacial bonding. However, noticeable cracks developed in the immersed and F-T specimens. These microscopic characteristics contributed to decreased mechanical properties for AFCS. The results of this research provide a reference for the engineering application of AFCS.

Hematology of Liolaemus pacha (Iguania: Liolaemidae) and its relationship with mite infestation, reproductive period and body condition.

Variations in hematological profile in reptiles can be caused by multiple factors, including parasites presence. Our goals were to identify and morphologically describe blood cells of Liolaemus pacha and analyze their relationship with sex, body condition, individual reproductive/post-reproductive period and mite infestation. Blood smear analyses do not indicate the presence of hemoparasites, suggesting that the mites Neopterygosoma do not serve as vectors for these organisms, as has been proposed for other genera of ectoparasitic mites. In post-reproductive period, there was a reduction in specimens' body condition and a higher leukocyte count in uninfected lizards. This could be a consequence of the testosterone effects, in higher concentration during the reproductive season, which can increase the metabolic rate, decreasing feeding rate. Infested and non-infested lizards showed no differences in body condition, as well as in leukocyte count, hence the host's immune system could be developing infestation tolerance. Infested specimens had a higher count of monocytes, thrombocytes, heterophils and lymphocytes. Based on cells function, mites' effect could be associated with inflammatory processes, allergic reactions or infectious diseases. These results suggested a complex interaction between lizards' hematological parameters and factors associated to ectoparasites or body conditions. We consider this work as a diagnostic tool for genus Liolaemus, to evaluate health quality, with relevance to the conservation or management of this lizard's genus.

Effects of type and distribution of clay minerals on the physico-chemical and geomechanical properties of engineered porous rocks

The study of the properties of engineered rocks is of great importance to researchers in engineering sciences such as petroleum, mining, and civil engineering owing to their wide application in these fields. In the present study, a physico-chemical and geomechanical investigation was carried out on the effects of different clay minerals on porous rocks. Various chemical products formed during chemical interactions between cement, clay minerals, and water can change the pore structure and thus the rock characteristics. The results of the current study showed that increasing the clay content could remarkably reduce the porosity and permeability of the rock by an average of 86% and 6.76%, respectively. In this regard, samples containing kaolinite were further influenced due to their new pore structure. Moreover, a power relationship was found between sonic velocity and porosity, which can be used to predict rock properties. Chemical analysis indicated an amplification in quantities of chemical products, particularly calcium silicate hydrate and portlandite, due to an increase in clay content. The impacts of porosity and cementation quality as two main factors on rock strength have also been studied. The outcomes revealed that a reduction in porosity could compensate for detrimental effects of poor bond quality and consequently improved UCS by up to 30% in samples containing kaolinite, while decreasing the degree of cementation prevailed over the porosity reduction in specimens including illite and resulted in a 14% decrease in UCS. The effects of porosity and bond quality on UCS would cancel each other out in samples containing bentonite. It is worth noting that when it comes to changes in geomechanical characteristics, the dominant factor (i.e., porosity reduction or cementation quality) determines the ultimate effect of clay minerals on the properties of engineered porous rocks.

Multinuclear MRI Reveals Early Efficacy of Stem Cell Therapy in Stroke.

Compromised adult human mesenchymal stem cells (hMSC) can impair cell therapy efficacy and further reverse ischemic recovery. However, in vitro assays require extended passage to characterize cells, limiting rapid assessment for therapeutic potency. Multinuclear magnetic resonance imaging and spectroscopy (MRI/S) provides near real-time feedback on disease progression and tissue recovery. Applied to ischemic stroke, 23Na MRI evaluates treatment efficacy within 24h after middle cerebral artery occlusion, showing recovery of sodium homeostasis and lesion reduction in specimens treated with hMSC while 1H MRS identifies reduction in lactate levels. This combined metric was confirmed by evaluating treatment groups receiving healthy or compromised hMSC versus vehicle (sham saline injection) over 21days. Behavioral tests to assess functional recovery and cell analysis for immunomodulatory and macrophage activity to detect hMSC potency confirm MR findings. Clinically, these MR metrics may prove critical to early evaluations of therapeutic efficacy and overall stroke recovery.

Investigation of Forging Metal Specimens of Different Relative Reductions Using Ultrasonic Waves.

Forgings produced in industry are an irreplaceable basis for subsequent elaborating on machine tools. The quality of the semi-finished product produced by forging is a necessary prerequisite for ensuring the final quality of the final product because the forging can produce some defects. The presented paper is aimed at investigation of selected characteristics of forging steel specimens for various levels of their relative reduction. Ultrasound testing belongs to methods for investigation of structure changes, including defects. Experimental investigation, using both the attenuation and velocity measurements, verify that the reduction of specimens’ material can have an effect on the propagation of ultrasound waves passing through the specimen body. The procedure of steel samples forging corresponds accordingly to the process of their hardening. The increase of toughness after relative reduction of forging in the range of 10–50% is with highest probability caused by the strength matrices development due to the relatively important deformation hardening. It is evident that the deformation hardening is almost the same after every 10% addition of relative reduction. Experiments are supplemented by Barkhausen noise detection and metallographic characteristics of the samples. While differences between the Barkhausen noise values are in principle relatively small and significant differences are only in the values of the position of the envelope, there is maximum coincidence with ultrasonic investigation.

Strengthening of RC Beam with Large Square Opening Using CFRP

The use of essential services in modern constructions, such pipes, and ducts, became important, placing these pipes and ducts underneath the soffit of the beam. They made a ceiling sandwich, and that causes to reduce the height of the floor, so the presence of the opening in the beam saves the height of the floor. In this paper, the investigation of the beam response of reinforced concrete simply supported rectangle beams with square web openings is presented, including a number of the web openings (two, four, and eight), in addition to its use in strengthening the member at the openings (when the beam is planned before casting, internal deformation steel bar is used, and in case of the opening is existing in the beam, (CFRP) fabric is used.). The test results indicated that the opening Strengthening of beams might compensate for the decrease of the beam load capacity because of the existence of the openings in the shear zone. The compensation of beam capacity depends on the strengthening method, which was adopted. The shear crack loads of the strengthened with externally CFRP specimen's reduction ranging from (15.38 to 38.46%) of their failure loads while the shear crack load of internally reinforced strengthened ranging from (15.38 to 30.76%).

Enhancing laboratory capacity during Ebola virus disease (EVD) heightened surveillance in Liberia: lessons learned and recommendations.

IntroductionFollowing a declaration by the World Health Organization that Liberia had successfully interrupted Ebola virus transmission on May 9th, 2015; the country entered a period of enhanced surveillance. The number of cases had significantly reduced prior to the declaration, leading to closure of eight out of eleven Ebola testing laboratories. Enhanced surveillance led to an abrupt increase in demand for laboratory services. We report interventions, achievements, lessons learned and recommendations drawn from enhancing laboratory capacity.MethodsUsing archived data, we reported before and after interventions that aimed at increasing laboratory capacity. Laboratory capacity was defined by number of laboratories with Ebola Virus Disease (EVD) testing capacity, number of competent staff, number of specimens tested, specimen backlog, daily and surge testing capacity, and turnaround time. Using Stata 14 (Stata Corporation, College Station, TX, USA), medians and trends were reported for all continuous variables.ResultsBetween May and December 2015, interventions including recruitment and training of eight staff, establishment of one EVD laboratory facility, implementation of ten Ebola GeneXpert diagnostic platforms, and establishment of working shifts yielded an 8-fold increase in number of specimens tested, a reduction in specimens backlog to zero, and restoration of turn-around time to 24 hours. This enabled a more efficient surveillance system that facilitated timely detection and containment of two EVD clusters observed thereafter.ConclusionEffective enhancement of laboratory services during high demand periods requires a combination of context-specific interventions. Building and ensuring sustainability of local capacity is an integral part of effective surveillance and disease outbreak response efforts.

Effect of the thickness reduction of specimens on the limit strains in thermomechanical tensile tests for hot-stamping studies

Sheet metal formability under hot stamping conditions has been evaluated using a novel planar testing system developed previously, being used within a Gleeble machine. Nevertheless, the specimen design with the central recess was not standardised, and the thickness reduction was not applied to the dog-bone type of specimen for testing at the uniaxial straining state. In this paper, effect of thickness reduction of dog-bone specimens on limit strain measurement under hot stamping conditions is investigated, and two types of dog-bone specimens without and with central recess are presented. Thermomechanical uniaxial tensile tests were performed at various deformation temperatures and strain rates, ranging from 370–510 °C and 0.01–1/s, respectively, by using the developed biaxial testing system in the Gleeble. The distributions of temperature and axial strain along gauge region of the two types of specimen were measured and compared. The specimen with consistent thickness had a better uniformity of temperature and strain distributions, compared to that with thickenss reduction. Forming limits for both types of specimen were also determined using the section-based international standard method. It is found that the accuracy of the calculation of forming limits based on the use of specimen with thickness reduction was highly dependent on the selection of the stage of the deformation of the specimen.

Effect of Posterior Malleolus Fracture on Syndesmosis Reduction

Category: Trauma Introduction/Purpose: Syndesmotic malreduction and the presence of posterior malleolus fractures negatively influence outcomes in rotational ankle fractures. While there are no universally accepted criteria for posterior malleolar fixation, it has recently been shown that posterior malleolar fixation contributed to the stability of the syndesmosis. However, little is known if and how anatomic or non-anatomic fixation of the posterior malleolus affects syndesmotic reduction. A study analyzing syndesmotic reduction in specimens with varying in size and quality of reduction of the posterior malleolus was conducted. Methods: Nine through-knee cadaveric specimens were randomized into two groups with small (a third of the fibular notch, n=4) and large (two-third of the fibular notch, n=5) posterior malleolar fragments. A model of stage IV supination external rotation injury after fibular repair was created by sharply releasing anterior inferior tibiofibular ligament, superficial and deep deltoid ligaments, and interosseous membrane. Posterior malleolar fracture with predefined sizing was created with preservation of posterior inferior tibiofibular ligament. High resolution CT scan was obtained in each specimen at the four stages; intact, neutral- axis syndesmotic clamping only, with anatomic fixation of the posterior malleolus, and with non-anatomic fixation of the posterior malleolus using a 4.8 mm interposed spacer. Measurement of syndesmotic reduction in both anteroposterior and mediolateral planes was made automatically using a validated technique assisted by custom-developed software at 1 cm proximal to the ankle joint. Results: The presence of either a neutral-axis clamping alone or with an anatomically reduced fracture fragment caused a slight anterior shift of the fibula that was more pronounced in the smaller fragment group. Two-way ANOVA indicated no significant effects of fragment size (p=0.73) or reduction (p=0.09) on AP fibular movement. However, presence of non-anatomical fixation caused the fibula to move significantly posteriorly in the presence of a large posterior malleolar fragment (p=0.03 and p=0.01 relative to the intact and clamping only states). In the mediolateral direction, a neutral-axis clamping alone and clamping with an anatomically reduced fracture fragment both increased medial translation of the distal fibula. The non-anatomic reduction model of the posterior malleolus associated with corresponding lateral displacement of the distal fibula. Conclusion: The overall anteroposterior reduction of the syndesmosis using neutral-axis clamping was generally not affected by posterior malleolar fracture except in a non-anatomic fixation of large fragments. Mediolateral syndesmotic reduction was affected by the conditions of posterior malleolar fixation with best results in anatomic fixation but the intact state was still not replicated. Malreduction of the posterior malleolus led to a corresponding syndesmotic malreduction. When a posterior malleolar fixation is indicated in cases with syndesmotic injury, anatomic fracture fixation is paramount as it can affect syndesmotic reduction especially with larger fragments.

Surface water conditions and calcium carbonate preservation in the Fram Strait during marine isotope stage 2, 28.8-15.4 kyr

[1] We present a high-resolution record of calcium carbonate preservation alongside the distribution pattern of planktic foraminifera from the Fram Strait. The record covers the marine isotope stage (MIS) 2, 28.8 to 15.4 kyr, including the Last Glacial Maximum (LGM) and the early deglaciation in multidecadal temporal resolution. The investigation is based on the distribution patterns of planktic foraminifera, stable isotopes, mean shell weight of Neogloboquadrina pachyderma, the degree of fragmentation of planktic shells, CaCO3 content, and geochemical and sedimentological data. The dissolution proxies indicate long-lasting periods of markedly reduced preservation of calcium carbonate at ~28.8–27.2, ~24.1–23.2, and ~16.6–15.4 kyr in addition to a number of short-lasting periods (< 300 year) during the LGM. These periods are accompanied by a simultaneous and significant reduction in specimens of subpolar planktic foraminifera indicating a southward expansion of Arctic surface water masses. Prolonged periods with high abundances of subpolar foraminiferal species and good preservation of calcium carbonate are attributed to increased influence of Atlantic water masses, which appears to persist throughout most of the MIS 2. Comparison to Holocene (MIS 1) shell weight records shows that the preservation during MIS 2 was overall better, even during the events of dissolution. This was probably a reflection of the low concentration of atmospheric CO2 at the time.

Zr-based coating for the prevention of silver tarnishing

Purpose – This work aims to focus on evaluation of the ability of cathodically deposited ZrO2-based coatings to stabilise the surface of silver against tarnishing caused by S2−-based species and comparison of these coatings with Cr oxide-based coating. Design/methodology/approach – The coatings were evaluated using inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), impedance spectroscopy (EIS) and galvanostatic reduction of specimens exposed to H2S vapours. Findings – The kinetics of deposition were studied and optimum conditions for coating formation were determined. The options of manual application suitable for practical use were studied also. Zr specimens showed better barrier properties than did a chromated specimen. The best properties were observed on a specimen with a manually fast-applied coating. However, Zr coating does not provide as good protection from tarnishing as chromate. The structure of the Cr coating contains species of chromate that oxidize species of S2−. Originality/value – The paper provides new information regarding the anticorrosive properties of cathodically deposited ZrO2 coating as an alternative to Cr coating for the preservation of silver surfaces.

Effect of Cold Rolling on Thermal Stability of Zr&lt;sub&gt; 55&lt;/sub&gt; Al&lt;sub&gt;10&lt;/sub&gt;Ni&lt;sub&gt;5&lt;/sub&gt;Cu&lt;sub&gt;30&lt;/sub&gt; Bulk Metallic Glass

The effect of cold rolling on thermal stability of bulk Zr55Al10Ni5Cu30 metallic glass at room temperature had been investigated by means of X-ray diffractometer, high-resolution transmission electron microscope and differential scanning calorimeter. A number of the cold rolling processes were carried out to obtain different thickness reduction in specimens with the same original size. The XRD patterns of cold rolled specimens with thickness reduction up to 95% showed no clear difference with that of completely amorphous specimens. The relationship of the deformation with the thermal parameters of cold rolled specimen indicates that with the increase of thickness reduction, the glass transition temperature decreases obviously and the crystallization onset temperature and peak temperature decreases slightly. At the same time, the enthalpy of crystallization peak keeps almost constant during rolling. These results have revealed that cold rolling deformation has an apparently effect on the glass transition process but slightly effect on the crystallization process of Zr55Al10Ni5Cu30 BMG.

Loading of forming presses by the upsetting of oblique specimens

The upsetting of oblique specimens as a means of loading forming presses with vertical and horizontal forces is a feasible concept, however, due to the changing distribution of conditions at the specimen interface, the scope of this approach needs to be quantified. The plastic deformation of oblique specimens was analysed using an FE code named PLAST2. The analysis suggests guidelines for the selection of test specimens and the scope of such tests; it is apparent that the lubrication conditions and specimen reduction, and the ratio between the vertical and horizontal forces, do not remain constant over the entire course of the deformation. Hence, the analysis of measurements of the behaviour of the press would be meaningful if the range of uniform behaviour of such tests was observed.

ブレージングシートのろう付時の変形と心材の組織との関係

A basic study has been made in order to obtain a brazing sheet having a high resistance to deformation during brazing. At first, the amount of deformation at brazing temperature of 610°C was measured on several brazingsheet specimens consisting of 4343 cladding alloy (both sides cladding) and Al-1.2%Mn base core alloys having no impurity or containing a small amount of Si, Fe, Cu, Mg, etc., as a function of cold reduction of specimens. Marked deformation was observed in the Si contained specimen (Si is added to the core alloy) cold-rolled by 515% and in the Fe contained specimen with a large reduction. Then, the two sorts of deformation were studied in detail in view of reaction at the interface between solid core and liquid phase of cladding alloy. It was found that the microstructure of core alloys at brazing temperature was of great importance for the stability of interface. It was concluded that in order to get an excellent brazing sheet, the core alloy was needed to show a completely recrystallized structure having coarse and elongated grains. The Al-Mn binary specimen free from impurity would satisfy the above condition.

Nonisothermal retardation of elastic fluids

It is shown that nonisothermy during the retardation of a polymer fluid after extension can result in diminution in specimen reduction.

加工中の変態によるKovarの異常硬化現象

Kovar alloy now being used for glass sealing consists of a single γ phase at room temperature. But according to the phase diagram, two phases of α and γ may exist in the equiliburium state. Therefore when its Ms point is not so low under room temperature, the transformation from γ to α phase may take place during cold-working and may cause a decrease of workability by abnormal hardening. In this experiment the characteristics of work-hardening in unstable Kovar were examined by measuring the change of hardness with rolling and the stress-strain curve in tensile tests. An abnormal hardening was observed after about 40∼50% reduction in specimens with low nickel content. The hardening degree of such specimens was about 100%, while it was about a half in specimens with high nickel content, after about 80% reduction. The former specimens also showed about 40% increase of hardness by a low temperature annealing and a slight softening by a cold treatment. A nickel content over 29∼29.5% was necessary to prevent Kovar from hardening by transformation during cold-working.