scholarly journals Effect of Storage Conditions of Rutile Flux Cored Welding Wires on Properties of Welds

2019 ◽  
Vol 19 (4) ◽  
pp. 46-56 ◽  
Author(s):  
A. Świerczyńska
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Atmospheric Corrosion ◽  
Surface Condition ◽  
Storage Conditions ◽  
Significant Difference ◽  
Strength Tests ◽  
Urban Conditions

AbstractThe influence of storage locations of two grades of rutile flux cored welding wires on their surface condition and the strength of the welds made with them were studied. Wires were stored in real urban conditions (Gdańsk and Katowice) for 1 month, simultaneously recording changes in conditions: temperature and relative humidity of the environment. Visual tests of wires in the delivered and stored condition as well as visual and tensile strength tests of welds made with them were carried out. It was found that the surface of the wires underwent more intense degradation (atmospheric corrosion) during storage in Katowice than in Gdańsk. Significant difference in tensile strength was observed only for padding welds made using Gdańsk stored wires. The lowest recorded tensile strength value was not lower than the standard requirements for the wires.

scholarly journals Lightweight concrete with Algerian limestone dust. Part II: study on 50% and 100% replacement to normal aggregate at timely age

Cerâmica ◽  
2015 ◽  
Vol 61 (360) ◽  
pp. 462-468 ◽  
Author(s):  
S. Kitouni ◽  
H. Houari
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Relative Humidity ◽  
Lightweight Concrete ◽  
Environmental Concern ◽  
Hardened Concrete ◽  
Dead Weight ◽  
Coarse Aggregates ◽  
Strength Tests ◽  
Limestone Dust

Abstract A control lightweight concrete (LWC) mixture made with 50% and 100% of limestone as a replacement of coarse aggregates in weight was prepared. Limestone is used for economical and environmental concern. The concrete samples were cured at 65% relative humidity at 20 ºC. The compressive and flexural tensile strengths, elastic modulus and Poisson's ratio of hardened concrete were measured. Laboratory compressive and tensile strength tests results showed that LWC can be produced by the use of limestone. The aim of this study is twofold: one is to design a lightweight concrete with the use of limestone that will provide an advantage of reduction in dead weight of a structure; and second is to obtain a more economical LWC mixture with the use of limestone.

scholarly journals Influence of Temporary Cements on the Bond Strength of Self-Adhesive Cement to the Metal Coronal Substrate

2015 ◽  
Vol 26 (6) ◽  
pp. 637-641
Author(s):  
Raniel Fernandes Peixoto ◽  
Caio Rocha de Aguiar ◽  
Eduardo Santana Jacob ◽  
Ana Paula Macedo ◽  
Maria da Gloria Chiarello de Mattos ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Bond Strength ◽  
Testing Machine ◽  
Resin Cement ◽  
Adhesive Resin ◽  
Cast Metal ◽  
Air Jet ◽  
Significant Difference ◽  
Strength Tests ◽  
Adhesive Resin Cement

This research evaluated the influence of temporary cements (eugenol-containing [EC] or eugenol-free [EF]) on the tensile strength of Ni-Cr copings fixed with self-adhesive resin cement to the metal coronal substrate. Thirty-six temporary crowns were divided into 4 groups (n=9) according to the temporary cements: Provy, Dentsply (eugenol-containing), Temp Cem, Vigodent (eugenol-containing), RelyX Temp NE, 3M ESPE (eugenol-free) and Temp Bond NE, Kerr Corp (eugenol-free). After 24 h of temporary cementation, tensile strength tests were performed in a universal testing machine at a crosshead speed of 0.5 mm/min and 1 kN (100 kgf) load cell. Afterwards, the cast metal cores were cleaned by scraping with curettes and air jet. Thirty-six Ni-Cr copings were cemented to the cast metal cores with self-adhesive resin cement (RelyX U200, 3M ESPE). Tensile strength tests were performed again. In the temporary cementation, Temp Bond NE (12.91±2.54) and Temp Cem (12.22±2.96) presented the highest values of tensile strength and were statistically similar to each other (p>0.05). Statistically significant difference (p<0.05) was observed only between Provy (164.44±31.23) and Temp Bond NE (88.48±21.83) after cementation of Ni-Cr copings with self-adhesive resin cement. In addition, Temp Cem (120.68±48.27) and RelyX Temp NE (103.04±26.09) showed intermediate tensile strength values. In conclusion, the Provy eugenol-containing temporary cement was associated with the highest bond strength among the resin cements when Ni-Cr copings were cemented to cast metal cores. However, the eugenol cannot be considered a determining factor in increased bond strength, since the other tested cements (1 eugenol-containing and 2 eugenol-free) were similar.

Impact of storage conditions on a new child-friendly dispersible tablet for treating Tuberculosis in pediatrics.

2021 ◽  
Author(s):  
Javier Suárez González ◽  
Ana Santoveña Estévez ◽  
Mabel Soriano ◽  
Jose Bruno Fariña
Keyword(s):  
Relative Humidity ◽  
Dosage Form ◽  
Storage Conditions ◽  
Weight Changes ◽  
Disintegration Time ◽  
Significant Difference ◽  
Dispersible Tablet ◽  
Child Friendly ◽  
New Formulation

Background: In 2020 the composition and procedure to elaborate a new formulation containing Isoniazid, Pyrazinamide and Rifampicin to treat tuberculosis in pediatric patients was published. The temperature and relative humidity in Tuberculosis-endemic countries are high, > 30ºC and > 70% respectively and thus these meteorological conditions required a new dosage form. The objective of this work is to register changes in tablet quality and stability over time when exposed to different storage conditions according to ICH. Method: Tablets were subjected to accelerated, long term and low relative humidity conditions. The effect of light was also tested. Quality was measured by evaluating weight changes tensile strength, disintegration time, and drug content. Hydrazine formation was also evaluated as it is considered a mutagenic degradation product. Results: Tablets stored at low relative humidity showed the best stability. There was no statistically significant difference between tablets exposed to or protected from light. Moreover, the formation of Hydrazine was not detected during stability studies. Conclusion: This new dosage form for treating Tuberculosis is stable and able to maintain its quality when appropriate storage conditions are used.

scholarly journals Influence of Storage Conditions on the Quality of Cotton Seeds in Benin Republic

2020 ◽  
Author(s):  
Roger IDOSSOU ◽  
Razack ABOUDOU
Keyword(s):  
Seed Germination ◽  
Relative Humidity ◽  
Germination Rate ◽  
Storage Conditions ◽  
Germination Capacity ◽  
Sampling Sequence ◽  
Significant Difference ◽  
Cotton Seeds ◽  
Benin Republic

Abstract Background The availability of good quality seeds is synonymous with improved farming, especially cash crops such as cotton. However, serious problems with seed germination have been reported recently by cotton farmers in Benin Republic. The assumptions formulated at the base with regard to this situation remain to be verified technically. Thus, this study aims to evaluate the influence of storage conditions on the quality of cotton seeds in Northern Benin. Temperature and relative humidity were assessed followed by a seed sampling sequence in seven (07) cotton seeds stores according to three main periods, ranging from the establishment in conservation to the following seasonal production. Germination tests were then carried out on each sample followed by data analysis using R and Minitab17 software.Results There is a large variation in the germination rate of cotton seed during their storage period. The probabilities values ​​(Pvalue1 = 0.023, Pvalue2 = 0.001 and Pvalue3 = 0.038) respectively associated with the three samples and the various coefficient of variation (CV) between stores (CV1 = 2.42%, CV2 = 7.1% and CV3 = 8.88%) explain a significant difference not only between the stores but also from one sample to another with regard to sampling periods. There is a strong progressive decrease in seed germination (Germination rate 1 > Germination rate2 > Germination rate3), which is responsible for the failure observed by the growers during sowing. Thus, seeds lose an average of 15% of their initial germination capacity already at one month of storage. This is generally negative due to all the storage conditions and system in the stores.Conclusions The excessive increase in temperature and the considerable decrease in relative humidity in stores are the main factors of significant loss of germination capacity of cotton seeds. In view of this situation, it is desirable that technical measures be taken in this direction in order to better preserve the quality of the seeds made available to producers for an optimization of the cotton sector in Benin.

Study of Bismuth Telluride Crystal Strength

2019 ◽  
pp. 1-8
Author(s):  
A. A. Gorbatovskiy
Keyword(s):  
Tensile Strength ◽  
Bismuth Telluride ◽  
Elasticity Modulus ◽  
Testing Machine ◽  
Bend Testing ◽  
Instron Testing Machine ◽  
Measurement Results ◽  
Strength Tests ◽  
Semiconductor Properties

The article presents results of strength tests of bismuth telluride prismatic samples obtained by growing crystals. These crystals have semiconductor properties and are used in the heat machines, the run-ability of which largely depends on the strength of crystals. Data available in the literature are significantly different from each other. It has been shown that, the most consistent strength tests results are obtained in case of bend testing. The measurement results of the elasticity modulus and tensile strength are given. For tests, an INSTRON testing machine with maximum direct stress of the 1000 H was used.

scholarly journals Seed longevity of maize conserved under germplasm bank conditions for up to 60 years

2021 ◽  
Author(s):  
Filippo Guzzon ◽  
Maraeva Gianella ◽  
Jose Alejandro Velazquez Juarez ◽  
Cesar Sanchez Cano ◽  
Denise E Costich
Keyword(s):  
Seed Germination ◽  
Plant Genetic Resources ◽  
Seed Viability ◽  
Storage Conditions ◽  
Seed Longevity ◽  
Germplasm Bank ◽  
Significant Difference ◽  
Different Temperatures ◽  
Germination Experiments

Abstract Background and Aims The long-term conservation of seeds of plant genetic resources is of key importance for food security and preservation of agrobiodiversity. Nevertheless, there is scarce information available about seed longevity of many crops under germplasm bank conditions. Methods Through germination experiments as well as the analysis of historical monitoring data, we studied the decline in viability manifested by 1000 maize (Zea mays subsp. mays) seed accessions conserved for an average of 48 years at the CIMMYT germplasm bank, the largest maize seedbank in the world, under two cold storage conditions: an active (–3 °C; intended for seed distribution) and a base conservation chamber (–15 °C; for long-term conservation). Key Results Seed lots stored in the active chamber had a significantly lower and more variable seed germination, averaging 81.4 %, as compared with the seed lots conserved in the base chamber, averaging 92.1 %. The average seed viability detected in this study was higher in comparison with that found in other seed longevity studies on maize conserved under similar conditions. A significant difference was detected in seed germination and longevity estimates (e.g. p85 and p50) among accessions. Correlating seed longevity with seed traits and passport data, grain type showed the strongest correlation, with flint varieties being longer lived than floury and dent types. Conclusions The more rapid loss of seed viability detected in the active chamber suggests that the seed conservation approach, based on the storage of the same seed accessions in two chambers with different temperatures, might be counterproductive for overall long-term conservation and that base conditions should be applied in both. The significant differences detected in seed longevity among accessions underscores that different viability monitoring and regeneration intervals should be applied to groups of accessions showing different longevity profiles.

scholarly journals The effect of liquid nitrogen cooling on coal cracking and mechanical properties

2018 ◽  
Vol 36 (6) ◽  
pp. 1609-1628 ◽  
Author(s):  
Chengzheng Cai ◽  
Feng Gao ◽  
Yugui Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Acoustic Emission ◽  
Liquid Nitrogen ◽  
Wave Velocity ◽  
Count Rate ◽  
Initial State ◽  
Nitrogen Injection ◽  
Strength Tests ◽  
Liquid Nitrogen Cooling

Liquid nitrogen is a type of super-cryogenic fluid, which can cause the reservoir temperature to decrease significantly and thereby induce formation rock damage and cracking when it is injected into the wellbore as fracturing fluid. An experimental set-up was designed to monitor the acoustic emission signals of coal during its contact with cryogenic liquid nitrogen. Ultrasonic and tensile strength tests were then performed to investigate the effect of liquid nitrogen cooling on coal cracking and the changes in mechanical properties thereof. The results showed that acoustic emission phenomena occurred immediately as the coal sample came into contact with liquid nitrogen. This indicated that evident damage and cracking were induced by liquid nitrogen cooling. During liquid nitrogen injection, the ring-down count rate was high, and the cumulative ring-down counts also increased rapidly. Both the ring-down count rate and the cumulative ring-down counts during liquid nitrogen injection were much greater than those in the post-injection period. Liquid nitrogen cooling caused the micro-fissures inside the coal to expand, leading to a decrease in wave velocity and the deterioration in mechanical strength. The wave velocity, which was measured as soon as the sample was removed from the liquid nitrogen (i.e. the wave velocity was recorded in the cooling state), decreased by 14.46% on average. As the cryogenic samples recovered to room temperature, this value increased to 18.69%. In tensile strength tests, the tensile strengths of samples in cooling and cool-treated states were (on average) 17.39 and 31.43% less than those in initial state. These indicated that both during the cooling and heating processes, damage and cracking were generated within these coal samples, resulting in the acoustic emission phenomenon as well as the decrease in wave velocity and tensile strength.

Ageing Resistance of Bi-Layer Coating Systems for Dry Lubrication of Premium OCTG Connections

2021 ◽  
Author(s):  
Philippe Baska ◽  
Alexandre François-Heude ◽  
Cécile Millet ◽  
Florian Thebault
Keyword(s):  
Atmospheric Corrosion ◽  
Storage Conditions ◽  
Low Friction ◽  
Layer System ◽  
Pull Out ◽  
Cyclic Corrosion ◽  
Additional Protection ◽  
Resistance To Stress ◽  
Service Conditions ◽  
Completion Fluids

Abstract The latest dope-free configuration combines an electrodeposited zinc-nickel (ZnNi) plating, which provides anti-galling and most of anticorrosion properties, and an organic topcoat which provides lubrication through its low friction coefficient. This dry lubrication constitutes an alternative to storage and running dope meanwhile it improves running performances, reduces operational costs on the yard and rig and avoids dope discharge to the environment. Since the technology is "rig-ready", it must withstand the different risks of degradation occurring along its whole lifecycle. The present study aims at assessing the robustness towards ageing along storage on yards, transportation to the rig and or service life in well conditions. The performances of the different layers were checked stepwise, first assessing the ZnNi plating alone, and then considering the additional protection brought by thermoset topcoat. Regarding atmospheric corrosion, the characterization path involved both accelerated laboratory tests (such as the VDA 233-102 cyclic corrosion test) and outdoor exposures, under plastic protectors and after their removal, in different climates: temperate, desertic and tropical. The specimens were inspected regarding at: (i) efficiency of cathodic protection provided by the metallic coating; (ii) paint blistering, (iii) propagation of corrosion from a scribe down to substrate. Regarding rig operations, some examples of rig-return were reported and the compatibility with completion fluids, encountered in case of misrun and subsequent pull-out of the column, was checked though immersion in alkaline brines. In respect to the service in simulated well conditions, the resistance to Stress Corrosion Cracking (SCC) in brines were carried out to complete the former autoclave tests to assess resistance of carbon and stainless steel to well conditions. Both the ZnNi plating and the bi-layer system revealed lifetimes in storage conditions ranging from 3 to more than 5 years before any sign of significant degradation such as red rust, paint blistering or disbonding. According to cyclic corrosion tests results, higher lifetimes could be even expected thanks to the additional anticorrosion protection of the topcoat. Regarding exposure to completion fluids, the bilayer coating was shown to withstand 3000h exposure with no more than scarce rust indications. These results testify of the technology robustness from storage on yards to rig operations. In the multiple service conditions in wells, it was shown that the corrosion and cracking resistance of the substrate was not deteriorated by the plating presence, but instead improved in the multiple assessed well service conditions. The present communication updates the results of atmospheric corrosion compared to the former one [1] and it details new results after rig-return and regarding the risks of cracking.

Growth performance of Acheta domesticus and Gryllus bimaculatus production reared under improvised cage system for increased returns and food security

2020 ◽  
pp. 1-10
Author(s):  
C.A. Ngonga ◽  
C.O. Gor ◽  
E.A. Okuto ◽  
M.A. Ayieko
Keyword(s):  
Relative Humidity ◽  
Growth Performance ◽  
Additive Model ◽  
Acheta Domesticus ◽  
Cotton Wool ◽  
Conventional System ◽  
Gryllus Bimaculatus ◽  
Generalised Additive Model ◽  
Cage System ◽  
Significant Difference

Cricket farming is emerging as a new venture in Kenya poised to help alleviate protein deficiency and improve household living standards. However, competing, limited and unaffordable rearing systems constrain productivity and optimisation of this new enterprise. This study sought to evaluate the growth performance of Acheta domesticus and Gryllus bimaculatus reared in improvised cage system to assess its technical effectiveness. Twenty-day old of both species of crickets were separately reared in improvised and conventional cage systems for comparison purposes. Whereas an improvised cage system is a set of structure devised using locally available materials especially where the standard materials are limited, a conventional cage system is a set of structure made of standard and ordinary materials. The improvised system comprised of bamboo hideouts, clean scrap blankets for drinking and laying, cut bamboo stem as drinking platter and the plywood-based cages while conventional system comprised of egg carton hideouts, cotton-wool for drinking and laying, plastic petri-dishes, and plastic buckets. Each group of crickets (100 live crickets) was daily provided with equal amount of feed and water. Average weekly temperature and relative humidity profiles were recorded using HOBO data loggers. Further, 49 live crickets per treatment were randomly sampled and weighed weekly. Generalised additive model and analysis of variance were adopted to model the data therefrom using R. The cage system had a significant effect on the growth performance of the crickets. The mean weight of the cricket species differed, but not the interaction with the cage system. Similarly, species, temperature and relative humidity also influenced the growth performance. Compared to the conventional system, improvised cage system showed better results in realising high cricket productivity though there was no significant difference in growth performance between the two systems. The focus therefore should be to evaluate the egg productivity in scrap blanket in relation to cotton wool and cost effectiveness in improvised system to inform future farm decisions.

scholarly journals The response of Opalinus Clay when exposed to cyclic relative humidity variations

2016 ◽  
Author(s):  
Katrin M. Wild ◽  
Patric Walter ◽  
Florian Amann
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Environmental Changes ◽  
Opalinus Clay ◽  
Brazilian Tensile Strength ◽  
Internal Damage ◽  
Direction Parallel ◽  
Clay Shale ◽  
Retention Characteristic ◽  
Bedding Planes

Abstract. Clay shale specimens were exposed to cyclic relative humidity variations to investigate the response of the material to natural environmental changes. Opalinus Clay, a clay shale chosen as host rock for nuclear waste disposal in Switzerland, was utilized. The specimens were exposed to stepwise relative humidity cycles where they were alternately allowed to equilibrate at 66 and 93 % relative humidity. Principal strains were monitored throughout the experiments using strain gauges. After each relative humidity cycle, Brazilian tensile strength tests were performed to identify possible changes in tensile strength due to environmental degradation. Results showed that Opalinus Clay follows a cyclic swelling-shrinkage behaviour with irreversible expansion limited to the direction normal to bedding, suggesting that internal damage is restricted along the bedding planes. The Brazilian tensile strength in direction parallel and normal to bedding as well as the water retention characteristic remained unaffected by the RH variations.

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