Academic literature on the topic 'Stress Susceptibility Index (SSI)'

In order to study the effect of drought stress on eight cultivars corn (Zea mays L.), an experiment was conducted in a factorial experimental on the basis of randomized complete block design under two irrigated conditions during 2010-2011 cropping season. Twelve drought tolerance/resistance indices including stress tolerance index (STI), stress susceptibility index (SSI), tolerance index (TOL), geometric mean production (GMP), mean production (MP), yield index (YI), yield stability index (YSI), drought resistance index (DI), relative drought index (RDI), stress susceptibility percentage index (SSPI) and modified stress tolerance (K1STI and K2STI) were calculated based on grain yield under drought and irrigated conditions. Yield in stress and non-stress conditions were significantly and positively correlated with STI, GMP, MP, YI, TOL, DI, RDI, YSI, SSPI, K1STI, and K2STI and negatively correlated with SSI. Yield in stress and non-stress conditions were significantly and positively correlated with STI, GMP, MP, YI, TOL, DI, RDI, YSI, SSPI, K1STI, and K2STI and negatively correlated with SSI. Screening drought tolerant cultivars using ranking method, three dimensional plots discriminated cultivars ‘KSC720’, KSC 710GT and ‘KSC 700’ as the most drought tolerant. Cluster analysis classified the cultivars into three groups i.e., tolerant, susceptible and semi-susceptible to drought conditions. In general, Results of this study showed that among drought tolerance indices STI, YI, SSPI, K1STI, and K2STI can be used as the most suitable indicators for screening drought tolerant cultivars and ‘KSC720’, KSC 710 GT and ‘KSC 700’ had the highest tolerance to drought in our studies condition.

Aim: To identify drought tolerant rice genotypes for rainfed upland hills at reproductive stage through different drought tolerance indices, PCA Biplot Analysis and Cluster Analysis. Methodology: Forty eight rainfed upland genotypes were evaluated under drought stress at reproductive stage and non-stress (irrigated) conditions. Different drought tolerance indices viz., drought tolerance efficiency (DTE), mean productivity index (MPI), relative efficiency (REI), mean relative performance (MRP), stress tolerance index (STI), drought yield index(DYI), stress tolerance (TOL), stress susceptibility index (SSI) and Schneider’s stress susceptibility index (SSSI)were used for screening genotypes. Results: The reduction in grain yield was observed in all the genotypes grown under drought stress condition and the per cent reduction in grain yield between stress and non-stress trial varied from 23.62% to 67.69%. The highest value of DTE was recorded in VL 20541 (76.38%) whereas VL 20441 showed the highest value for MPI (2656), REI (1.478), MRP (2.44) and STI (0.79). The lowest value of DYI (1.31), TOL (625), SSI (0.51) and SSSI (-0.23) was observed in VL 20541. Highest value for DTE, MPI, REI, MRP, STI and lowest value for DYI, TOL, SSI, SSSI are preferred and desirable as it indicate drought tolerance. A positive and highly significant correlation was exhibited by grain yield under stress (YS) with DTE, MPI, REI, MRP, STI and highly negative significant with DYI, TOL, SSI SSSI indicating that selection of low DYI, TOL, SSI, SSSI value and high DTE, MPI, REI, MRP, STI for screening of rice genotypes under drought stresses condition. Principal component analysis revealed that PC1 and PC2 accounted for 80.05% and 19.40% of the total variations, respectively. Cluster analysis grouped the 48 rice genotypes into two main clusters. Interpretation: On the basis of drought tolerant indices, PCA Biplot analysis and Cluster analysis six genotypes viz., VL 20441, VL 20225, VL 20541, VL 20468, VL 8549, and VL 20316 were identified as drought tolerant.

In this study, seventy two sunflower recombinant inbred lines were tested for their yielding ability under both water-stressed and well-watered states. The inbred lines were evaluated in a rectangular 8?9 lattice design with two replications in both well-watered and water-stressed conditions, separately. Eight drought tolerance indices including stability tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated based on grain yield for every genotype. Results showed the highest values of mean productivity (MP) index, geometric mean productivity (GMP), yield index (YI), harmonic mean (HM) and stress tolerance index (STI) indices for ?C134a? inbred line and least values of stress susceptibility index (SSI) and tolerance (TOL) for C61 inbred line. According to correlation of indices with yield performance under both drought stress and non-stress states and principle component analysis, indices including HM, MP, GMP and STI could properly distinguish drought tolerant sunflower inbred lines with high yield performance under both states. Cluster analysis of inbred lines using Ys, Yp and eight indices, categorized them into four groups including 19, 6, 26 and 19 inbred lines.

Investigation comprised 41 tomato genotypes originating from the population of domestic and domesticated genotypes collected in Serbia and belonging to the tomato collection of the Institute of Vegetable Crop Science, Smederevska Palanka. The aim of collection screening was to choose the genotypes tolerant to drought during plant intensive growth stage, whereby the process of selection would set out to obtain the recombinant genotypes for this abiotic factor. The screening criteria were established for genotype divergence in plant height and shoot-root ratio under conditions of optimal irrigation regime and drought. Divergence was estimated using cluster analysis with Euclidean distance as a measure of distance, with a complete gene attachment to grouping. Drought tolerance is expressed by the stress susceptibility index (SSI). Various results were obtained based on the screening of genotypes grown under optimal and dry conditions. As a measure of stress susceptibility, based on SSI, genotypes having different drought tolerance level were determined. On the grounds of the analyses carried out, 10 genotypes were segregated (G102, G104, G107, G109, G110, G119, G125, G126, G128 and G141) to represent a basis to obtain the recombinant genotypes and to initiate the selection for drought resistance.

Abstract Most of investigations showed that nitrogen fertilizers gave substantial rapeseed yield increases even in diverse and contradicting conditions but in a few studies were focused on nitrogen deficiency stress effects. Some of important seed yield stress indices based on application and non application of nitrogen (N+ and N0) was studied using six spring rapeseed varieties and their 15 F2 progenies. Significant mean squares of genotypes effects were observed for potential yield (Yp), stress yield (Ys), mean productivity (MP), geometric mean productivity (GMP), tolerance index (TOL), stress tolerance index (STI) and stress susceptibility index (SSI), indicating significant genetic differences of the genotypes for the stress indices. The genotypes including PF7045/91 and RGS003 had the high mean values of MP and GMP and STI, therefore considered as high potential parents in both nitrogen application conditions. On the basis of low mean value of TOL and SSI indices, PF7045/91 and 19H were considered as tolerant to nitrogen deficiency stress. Most of the crosses with high mean values of MP, GMP and STI had at least one parent with high mean values of these stress indices. Significant positive correlation of Yp and Ys with MP, GMP and STI, indicating selection based on these stress indices will increase the Yp and Ys of the genotypes. Heterozygosity had important role for stability of traits in different conditions, therefore in compare to parents their F2 progenies had low mean values of SSI and TOL indices.

Keakuratan dalam seleksi jagung hibrida toleran N rendah dapat ditingkatkan dengan penggunaan beberapa indeks seleksi secara sekaligus. Penelitian ini bertujuan mengidentifikasi indeks toleransi yang sesuai untuk seleksi jagung hibrida toleran N rendah serta memilih jagung hibrida toleran N rendah. Penelitian dilaksanakan di IP2TP Bajeng Balai Penelitian Tanaman Serealia Kabupaten Gowa bulan April sampai dengan September 2021. Sebanyak 8 hibrida dan 2 varietas pembanding ditanam pada rancangan tersarang tiga ulangan. Genotipe tersarang pada taraf pupuk N. Taraf pupuk N meliputi 100 kg N ha-1 dan 200 kg N ha-1. Indeks toleransi meliputi Tolerance (TOL), Mean Productivity (MP), Geometric Mean Productivity (GMP), Harmonic Mean (HM), Stress Tolerant Index (STI), Relative Tolerant Index (RTI), Stress Susceptibility Index (SSI), Yield Index (YI), Stress Relative Index (SI), Yield Stability Index (YSI), Stress Susceptibility Percentage Index (SSPI). Hasil penelitian menunjukkan bahwa indeks toleransi menunjukkan bahwa MP, GMP, HM dan STI merupakan yang paling sesuai untuk menyeleksi hibrida toleran N rendah. Hibrida HLN 02 dan HLN 06 merupakan hibrida yang toleran terhadap N rendah, sedangkan Hibrida HLN 03 dan HLN 07 dan ADV 777 termasuk peka. Berdasarkan hasil biji pada pemupukan 100 kg N ha-1 dan 200 kg N ha-1 dan indeks toleransi serta analisis kluster.ABSTRACTLow N tolerant hybrid maize selection accuracy can be increased by using several selection indices simultaneously. This study's objective was to identify the proper tolerance index for low N tolerant hybrid maize selection and to determine the low N tolerant hybrid maize. The research was conducted at IP2TP Bajeng Indonesian Cereal Crop Institute Gowa Regency from April to September 2021. Eight promising hybrid and two check varieties were planted in a nested design with three replications. The genotypes were nested at the N fertilizer level. The N fertilizer levels were 100 kg N ha-1 and 200 kg N ha-1. The tolerance index used was Tolerance (TOL), Mean Productivity (MP), Geometric Mean Productivity (GMP), Harmonic Mean (HM), Stress Tolerant Index (STI), Relative Tolerant Index (RTI), Stress Susceptibility Index (SSI), Yield Index (YI), Stress Relative Index (SI), Yield Stability Index (YSI), Stress Susceptibility Percentage Index (SSPI). The results showed that tolerance index MP, GMP, HM, and STI were the most suitable for electing low N tolerant hybrids maize. hybrids HLN 02 and HLN 06 were low N tolerant; meanwhile, HLN 03 and HLN 07 and ADV 777 were susceptible based on yields at 100 kg N ha-1 and 200 kg N ha-1 fertilization, tolerant indexes, and clustering.

Abstract A set of fifty two hybrids developed through line×tester breeding design were sown in randomized block design with three replications to evaluate their performance for seed yield under two environments (normal irrigation and water stress). Drought resistant indices and multivariate statistical analysis from the pooled data obtained from water stress and normal irrigated environments over the two years. Hybrid PRUN-29A × RCR-8297 (1.55) and 40A × P100R (1.55) had the largest stress tolerance index (STI) rate and hybrid ARG-2A × P69R the smallest rate (a high STI rate for the genotype represents its high drought resistance and its high yielding potential). Hybrid ARG-6A × P69R (2.41) had the largest extent (susceptible) of Stress susceptibility index (SSI), while hybrid E002-91 × RCR-8297 (0.13) had the least (resistant) extent a large extent of this index indicates the genotype susceptibility to drought. In terms of yield stability index (YSI), hybrid 40A × RCR-8297 (0.51) and ARG-6A × P69R (0.51) and hybrid ARG-2A × P69R (1.18) had the smallest and the largest rate respectively (genotypes with high YSI are expected to yield highly in stress conditions. Hybrid 40A × RCR-8297 (30.36) and PRUN-29A × P69R (−10.07) displayed the least and the most amount of tolerance index (TOL) index, a high amount of TOL is a sign of genotype susceptibility to stress. Hybrid PRUN-29A × P69R (1.53) displayed the least extent of yield index (YI), while hybrid ARG-6A × P69R (0.51) and 40A × RCR-8297 (0.51) displayed the highest extent.

The impacts of high-temperature stress on rice growth and productivity can be mitigated by growing tolerant varieties. This research was conducted to estimate the genetic parameters and to select the best genotypes based on the susceptibility stress index (SSI) values. This research was conducted from August 2016 to February 2017. Half of the five weeks seedling tiller of each F3 plant was transferred to new pot culture so that each genotype of the F3 rice population grown in two pots. At the maximum vegetative phase, the parental and F3 populations were treated under two different temperatures: in the open ground area and inside a greenhouse with daily mean temperatures of 38.89/22.67 °C dan 41.62/23.32 °C, respectively. The traits observed were yield and yield components. The results showed that the grain yield of the parents and the F3 population were lower when grown inside the greenhouse. The filled grain number per panicle was controlled by additive gene action in these two environments, and is suggested to be a selection character. Selection based on SSI index obtained 13 genotypes tolerant to heat stress and had higher yield compared to their parents. SSD method combined with shuttle breeding is recommended as a breeding method to produce tolerant and high yielding lines. Keywords: heat stress, heritability, segregating population, SSI

Rice is an important cereal crop and its productivity is being affected by many abiotic and biotic stresses. High temperature affects the rice yield and productivity. Thirty rice genotypes were evaluated in normal and under high temperature stress conditions. There was reduction in grain yield in all the tested genotypes. Based on yield recorded under normal and high temperature conditions, yield based indices were calculated. Stress Susceptibility Index (SSI), Geometric Mean Production (GMP), Mean Production (MP), Yield Index (YI), Modified stress tolerance (K1STI and K2STI) were significantly and positively correlated to yield under both stress and non-stress conditions and could be considered as good selection indices for screening for heat tolerance. Genotypes were ranked based on their tolerant or susceptibility indices and it was noted that among all IET 28412, IET 28397 and IET 28432 exhibited highest mean rank and a lower standard deviation of rank, hence they can be identified as heat tolerant genotypes. Genotypes IET 26468, IET 28393 and Gontrabidhan-3 were identified as highly susceptible to high temperature stress.

Abstract Twenty five spring wheat genotypes were evaluated for terminal heat stress tolerance in field environments in the Agro Ecological Zone-11 of Bangladesh, during 2009-2010 cropping season. The experiments were conducted at Wheat Research Centre, Bangladesh Agricultural Research Institute, using randomized block design with three replicates under non-stress (optimum sowing) and stress (late sowing) conditions. Seven selection indices for stress tolerance including mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), yield index (YI), yield stability index (YSI), stress tolerance index (STI) and stress susceptibility index (SSI) were calculated based on grain yield of wheat under optimum and late sowing conditions. The results revealed significant variations due to genotypes for all characters in two sowing conditions. Principal component analysis revealed that the first PCA explained 0.64 of the variation with MP, GMP, YI and STI. Using MP, GMP, YI and STI, the genotypes G-05 and G-22 were found to be the best genotypes with relatively high yield and suitable for both optimum and late heat stressed conditions. The indices SSI, YSI and TOL could be useful parameters in discriminating the tolerant genotypes (G-12, G-13, and G-14) that might be recommended for heat stressed conditions. It is also concluded from the present studies that biomass, grain filling rate and spikes number m-2 are suitable for selecting the best genotypes under optimum and late sowing conditions because these parameters are highly correlated with MP, GMP, YI and STI. However, high ground cover with long pre heading stage and having high grain filling rate would made a genotype tolerant to late heat to attain a high grain yield in wheat.

Soil salinity is one of the environmental constraints that affect crop cultivation worldwide. Among cereals, rice (Oryza sativa L.) is one of the most salt-sensitive although cultivars can differ in their response to salt stress. In European coastal rice areas, the salt wedge intrusion phenomenon caused by the rise in the sea levels consequent to the ongoing climate changes is provoking a tendency toward salinization in the adjacent paddy fields and coastal areas where rice is grown. Thus, the identification of rice cultivars tolerant to salt stress and the dissection of salt stress tolerance mechanisms are of high interest for European rice breeding. Plant responses to salt stress are complex depending on the combination of the activity of many metabolic pathways and of the several involved genes, and thus they are difficult to control and/or engineer. Exploiting natural variation that occurs in worldwide genotypes may be a powerful approach to discover new genes and/or alleles involved in salt tolerance. Since salinity has many different effects on plants, several different tolerance mechanisms (osmotic tolerance, ion exclusion and/or tissue tolerance) exist. The predominance of a specific tolerance mechanism over others depends on salt stress intensity (severity x duration) and plant developmental stage. Concerning indica rice subspecies, several QTLs and some genes involved in the phenotypic variability in response to salt stress have been identified and exploited in breeding programs for genetic improvement of élite varieties. On the contrary, in the case of japonica subspecies, far fewer information are available. General objective of this work is the discovery of novel molecular variability at different developmental stages in japonica rice cultivars resulting in tolerance to the mild salt stress conditionsreported for some European rice areas. In major detail, possible research deliverables are the identification of QTLs, alleles and/or molecular markers exploitable in future genetic improvement programs. The stated goal was pursued by a Genome Wide Association Study (GWAS) using a panel of 277 accessions of japonica rice already genotyped-by-sequencing producing 31,421 SNPs. The accession panel was subjected to a two-year phenotyping through the evaluation, at different growth stages, of traits [leaf visual injuries score (SES), tillering rate, plant height, flowering time, flag leaf chlorophyll index, and flowering time] sensitive to salt stress. For these activities, plants were grown in greenhouse environment, in pots filled with paddy soil maintained submerged and, starting from the 4th leaf stage, subjected to about 5 dSm-1soil electric conductivity (ECe) by the addition of adequate NaCl amounts.For all the measurements obtained from the two-years data, the Least Mean Square (LMS) were calculated. To be able to compare two-year data and different parameters with different range amplitudes, all data were standardized by Z-score transformation, and subjected to two-step cluster analysis, achieving a Core Collection of the 5 most tolerant and the 5 most susceptible varieties in response to salt stress. Moreover, the seed germination dynamics and the seedling emergence rate were analyzed under high salt environment (150 mM NaCl for germination, and about 10 dSm-1 soil ECe for emergence) in a single-year experiment. For each of the 277 rice accessions the effect of salt on each trait was evaluated in terms of Stress Susceptibility Index (SSI) evaluating the performance of a single accession in relation to the whole collection. An association analysis between the phenotyping and the GBS results was carried out using Tassel 3.0 to calculate a Mixed Linear Model (MLM). The critical p-values for assessing the significance of SNPs were calculated based on a False Discovery Rate (FDR) separately for each trait; a FDR cut-off of α 0.05 was used for determining significance. Currently, a total of 33 Marker-Trait Associations (MTAs) between SNPs and the analyzed salt stress-related traits have been identified. Several loci were subsequently identified by intersecting the MTAs with the genes annotated on the Nipponbare reference genome. GWAS analysis carried out on germination and emergence parameters highlighted the presence of interesting associations between two markers and two loci in linkage disequilibrium with them: Os09g0369400 and Os07g0485000, coding for a Trehalose 6-Phosphate Phosphatase 7 (OsTPP7) and a Trehalose 6-Phosphate Phosphatase 10 (OsTPP10), respectively, known to be involved in anoxia and salt stress response. Members of the OsTPPs family playing a role in the Trehalose-6P (T6P)/SnRK1 system that regulates the C-metabolism under stress conditions. Indeed, high levels of T6P inhibit the cell energetic metabolism that is, on the contrary, stimulated when T6P is dephosphorylated by TPPs activities. The possible involvement of OsTPP7/10 in this regulative network and in the different salt sensitiveness of the different rice accessions has been investigated in two japonica accessions Olcenengo and SR113, salt tolerant and sensitive, respectively. The results obtained indicate that under salt condition (NaCl 150 mM) the coleoptile growth rate is less affected in Olcenengo where the T6P levels are quite lower than in SR113. The rate of growth in the controls appeared after 24 h from sowing and it was greater in Olcenengo than in SR113. Salt stress reduces coleoptile growth rate in each genotype but in SR113 the effect was more marked. In salt condition, Olcenengo showed a higher and earlier OsTPP10 expression than SR113; this could trigger SnRK1 activity and thus the mobilization of starch (α-amylase activity), supporting the energy needed for seed germination and coleoptile elongation under salt stress. The data confirmed that in the general framework of stress tolerance, members of the OsTPPs family play a key role to overcome saline stress during the first stages of germination. Moreover, on the basis of GWAS carried out on SES parameter, a QTL including a few genes that in the indica rice genome are localized within the major salinity tolerance-related QTL ‘SalTol’ have been identified. Among them, the gene encoding the vacuolar H+-pyrophosphatase 6 (OsOVP6) is present. Since OsOVP6 activity is suggested to be important in the network of the transport activities concerning Na+ and K+ transmembrane movement related to plant salt stress susceptibility/tolerance, an in depth physiological approach evaluating this possibility has been conducted. Two japonica salt-tolerant varieties (Galileo and Virgo), one japonica rice variety (PL12) known to be salt-susceptible, and the salt-tolerant indica genotype FL478 (containing the ‘SalTol’ QTL) have been considered. The Na+/K+ ratio, Na+ influx and K+ efflux, H+ extrusion, cytosolic and vacuolar pH by in vivo 31P-NMR techniques were evaluated in roots. The results obtained, together with the electrophysiological evaluation of the whole root Na+ conductance, allow to define a picture that may explain the different salt tolerance observed among the genotypes analyzed. In this picture, OsOVP6 plays a central role. In general, good variability within the population was observed for all the analyzed parameters. Salt stress tolerance is a multi-genic complex trait, and GWAS has proven to be a powerful tool for detecting natural variation underlying complex traits in crops. Through association analysis, several MTAs have been highlighted, with the identification of interesting loci, involved in the salt stress response. In particular, the idea of the function of two genes belonging to the OsTPPs family has been reinforced, confirming that in the general framework of salt tolerance, OsTPPs play a key role to overcome the stress during the germination stages. In this context, two varieties with contrasting behavior have been identified within the collection, Olcenengo and SR113, very tolerant and susceptible, respectively. Moreover, the idea of the vacuolar H+-pyrophosphatase function has been reinforced, too, since OsOVP6 activity is suggested to be important in the network of the transport activities concerning Na+ and K+ transmembrane movement related to plant salt stress tolerance. Finally, by evaluating the overall performance of each genotype of the population in relation to each parameter measured along the two-years experiment, a "core collection" of the 5 most tolerant and the 5 most susceptible varieties has been identified.

The incidence of alcoholic liver disease (ALD) follows the trend of per capita alcohol consumption, with hepatic injury which extends from fatty liver to alcoholic hepatitis and cirrhosis. It is unclear how alcohol causes liver disease, but postulated mechanisms include (1) oxidative stress and acetaldehyde generated by the metabolism of ethanol, and (2) innate and adaptive immune responses. Factors determining the susceptibility to liver disease in heavy drinkers are believed to include a variety of host and environmental factors, with genetic factors increasingly recognized. Clinical manifestations are extremely variable, and some patients remain relatively well while others suffer the effects of severe hepatic failure. Although patients can come to light with a life-threatening complication, most often they develop symptoms which are not immediately related to the liver, such as nonspecific digestive symptoms or psychiatric complaints. The key to the early recognition of alcohol-related disease is having a high index of suspicion, with confirmation by (1) direct questioning for alcohol history and alcohol-related symptoms; (2) clinical examination for signs of chronic liver disease; (3) supportive investigations, including aspartate aminotransferase, which is less than 500 IU/litre and greater than the alanine aminotransferase level; and (4) liver biopsy, which may be required in some cases of diagnostic uncertainty and to confirm the stage of the disease, revealing alcoholic fatty liver, alcoholic hepatitis, or cirrhosis. Management is governed by the stage and severity of the liver disease, but always includes abstinence and adequate nutritional support. In selected patients with severe acute alcoholic hepatitis, corticosteroids can reduce short-term mortality. Transplantation remains the only effective treatment for advanced alcoholic cirrhosis, although this remains controversial, mainly because of concerns about post-transplant recidivism.

The 2010 version of B31.3 introduced sustained stress indices (SSI’s) in paragraph 320. Using methods in references [1],[2],[3],[4],[5], and [11], a test procedure was developed to evaluate these SSI’s for standard metallic piping components. The test procedure has been incorporated into draft versions of B31J so that the sustained stress index can be produced at the same time stress intensification or flexibility factor tests are performed for a particular component. This paper describes the sustained stress index and the B31J test procedure used to determine the SSI.

The stress corrosion cracking susceptibilities of type 16MnR low-alloy steel in simulated oil refining environment were investigated by slow strain rate test. Many research works have been done to study the single solution parameter effect on the stress corrosion cracking, such as H2S concentration or Cl− content, but less had been done for the interactive effect of the multiparameter. In this work, the separate and interactive effects of H2S concentration, Cl− content, temperature and pH value on stress corrosion cracking susceptibilities were studied. By stepwise regression analysis of test results, the effect notabilities of medium parameters on stress corrosion cracking susceptive index were revealed. It could be conclude that the effect of H2S concentrations was most notable to susceptive indexes, there was no notable correlativity between Cl− content and susceptive indexes, temperature and H2S played interactive role on the susceptive indexes.

Abstract Field experience on pipelines suggests that under the unique conditions of tie-in welding, a high-low offset at the inner pipe wall is related to an increased occurrence of latent root weld discontinuities such as cold cracking. Codes and standards offer conflicting and unclear guidelines regarding acceptance criteria for high-low offset. This study presents a numerical index to quantify the influence of non-ideal joint geometry on the latent discontinuity susceptibility of the root pass for circumferential pipeline welds. The index is based on the stress concentration at the root and the angular distortion associated with plastic strains produced during welding. This index relates geometric considerations such as pipe diameter, wall thickness, and the cross section of the root pass with welding procedure variables and the mechanical properties of the pipeline material. Although this study is meant for steel pipelines, the conclusions obtained are also applicable to other materials. The index presented is a contribution towards an objective criterion for acceptance of high-low offset during field welding, ranking the susceptibility to latent discontinuities as a function of variables available to practitioners during field welding.

The electrochemical behavior of duplex stainless steel has been studied in various environments. Its passivity state was investigated in borate-buffer using cyclic voltammetry and impedance spectroscopy techniques. The susceptibility towards sulfide stress cracking and hydrogen embrittlement were tested at a constant load under cathodic polarization in the NACE solution saturated with H2S and 0.5 M sulfuric acid solution containing As203 as a promoter. SEM analysis accompanied these investigations. It is proposed that the highly protective quality of the passive film formed on the investigated duplex stainless steel may be associated with the presence of multiple oxidation states (Cr3+ and Cr6+) formed in the solid state along with (CrO42- and MoO42-) anions and the great variety of possible bridging ligand states (OH−, H2O, O2−). This leads to a significant degree of bonding flexibility and supports amorphous i.e. glassy structure of the passive film. Therefore, the stresses that would be associated with epitaxy, are easily alleviated without the creation of long-range defect structures. The investigated duplex stainless steel shows high resistance to hydrogen embrittlement and sulfide stress cracking. The embrittlement index was determined to be 26%, while the threshold stress amounts to 84% of the yield strength.

Abstract In recent decades, a remarkable increase in induced seismicity in the Western Canada Sedimentary Basin (WCSB) has been largely attributed to the hydraulic fracturing (HF) operations in unconventional plays. However, a mitigation strategy concerning geological, geomechanical, and operational susceptibilities to HF-induced seismicity has not been well understood. In this work, an integrated method is proposed to mitigate potential risks from HF-induced seismicity in the Duvernay play near Crooked Lake. The geological susceptibility to induced seismicity is evaluated first from site-specific formation pressure, a distance to the Precambrian Basement, and the existence of pre-existing faults. The regional in-situ stress and rock mechanics are then assessed to determine the geomechanical susceptibility to induced seismicity. Next, the operational susceptibility is determined by comparing induced seismicity with operational parameters such as total injection fluids and proppant mass. Finally, a multiple linear regression (MLR)-based approach is proposed by considering the feature importance of different parameters. It is found that regions with a low formation pressure (<60MPa), a great distance to the Precambrian Basement (>260m), a low minimum principal stress (<70MPa), and a low brittleness index (<0.62) tend to be seismicity-quiescent regions. Three new horizontal wells are drilled and fractured to validate the applicability of our MLR-based approach. High-resolution monitoring results indicated that 95% of the induced events had a magnitude of less than 2.0 during and after HF operations (three-month time window and five-kilometer well-event distance), among which the maximum magnitude reached M3.05 (<red light magnitude M4.0). Therefore, the MLR-based approach was successful in mitigating potential seismicity risks, which can be applied to other regions to guide seismicity-free fracturing operations in unconventional plays.