bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the food additive monosodium glutamate on cisplatin‐induced gastrointestinal dysmotility and peripheral neuropathy in the rat
Authors: López‐Tofiño Yolanda , Vera Gema , López‐Gómez Laura , Girón Rocío , Nurgali Kulmira , Uranga Jose A. , Abalo Raquel
Published: October 2020

Background

Cisplatin is an antineoplastic drug known to produce intense vomiting, gastric dysmotility, and peripheral neuropathy. Monosodium glutamate (MSG) is a flavor enhancer with prokinetic properties potentially useful for cancer patients under chemotherapy. Our aim was to test whether MSG may improve gastrointestinal motor dysfunction and other adverse effects induced by repeated cisplatin in rats.

Methods

Male Wistar rats were exposed or not to MSG (4 g L−1) in drinking water from week 0 to 1 week after treatment. On the first day of weeks 1–5, rats were treated with saline or cisplatin (2 mg kg−1 week−1, ip). Gastrointestinal motility was measured by radiological methods after first and fifth administrations, as well as 1 week after treatment finalization. One week after treatment, the threshold for mechanical somatic sensitivity was recorded. Finally, samples of stomach, terminal ileum and kidneys were evaluated in sections using conventional histology. The myenteric plexus was immunohistochemically evaluated on distal colon whole‐mount preparations.

Key Results

Monosodium glutamate prevented the development of cisplatin‐induced neuropathy and partially improved intestinal transit after the fifth cisplatin administration with little impact on gastric dysmotility. MSG did not improve the histological damage of gut wall, but prevented the changes induced by cisplatin in the colonic myenteric plexus.

Conclusion and Inferences

Our results suggest that MSG can improve some dysfunctions caused by anticancer chemotherapy in the gut and other systems, associated, at least partially, with neuroprotectant effects. The potentially useful adjuvant role of this food additive to reduce chemotherapy‐induced sequelae warrants further evaluation.
Climate change alters plant–herbivore interactions
Authors: Hamann Elena , Blevins Camille , Franks Steven J. , Jameel M. Inam , Anderson Jill T.
Published: October 2020

Plant–herbivore interactions have evolved in response to coevolutionary dynamics, along with selection driven by abiotic conditions. We examine how abiotic factors influence trait expression in both plants and herbivores to evaluate how climate change will alter this long‐standing interaction. The paleontological record documents increased herbivory during periods of global warming in the deep past. In phylogenetically corrected meta‐analyses, we find that elevated temperatures, CO2 concentrations, drought stress and nutrient conditions directly and indirectly induce greater food consumption by herbivores. Additionally, elevated CO2 delays herbivore development, but increased temperatures accelerate development. For annual plants, higher temperatures, CO2 and drought stress increase foliar herbivory. Our meta‐analysis also suggests that greater temperatures and drought may heighten florivory in perennials. Human actions are causing concurrent shifts in CO2, temperature, precipitation regimes and nitrogen deposition, yet few studies evaluate interactions among these changing conditions. We call for additional multifactorial studies that simultaneously manipulate multiple climatic factors, which will enable us to generate more robust predictions of how climate change could disrupt plant–herbivore interactions. Finally, we consider how shifts in insect and plant phenology and distribution patterns could lead to ecological mismatches, and how these changes may drive future adaptation and coevolution between interacting species.
Canopy processing of N deposition increases short‐term leaf N uptake and photosynthesis, but not long‐term N retention for aspen seedlings
Authors: Wang Xin , Wang Bin , Wang Chengzhang , Wang Zhenhua , Li Jing , Jia Zhou , Yang Sen , Li Ping , Wu Yuntao , Pan Shengnan , Liu Lingli
Published: October 2020

Forest canopies can retain nitrogen (N) from atmospheric deposition. However, most empirical and modeling studies do not consider the processing of the N deposited in the canopy.

To assess whether N deposition through canopy will alter the plant’s N uptake and retention, we conducted a 3‐yr mesocosm experiment by applying (15NH4)2SO4 solution to aspen sapling canopies or directly to the soil.

We found that 15N‐NH4+ applied to the canopy was directly taken up by leaves. Compared with the soil N application, the canopy N application resulted in higher photosynthesis but lower N retention of the plant–soil system in the first growing season. Plant biomass, N concentration, and leaf N resorption were not significantly different between the canopy and soil N applications. The partitioning of retained 15N among plant components and soil layers was similar between the two treatments 3 yr after the N application.

Our findings indicated that the canopy N processing could alter leaf N supply and photosynthesis in the short term but not N retention in the long term. Under natural conditions, the chronic N deposition could continuously refill the canopy N pool, causing a sustained increase in canopy carbon uptake. Canopy N processing needs to be considered for accurately predicting the impact of N deposition.
Presence of Ebola virus in breast milk and risk of mother‐to‐child transmission: synthesis of evidence
Authors: Medina‐Rivera Melisa , Centeno‐Tablante Elizabeth , Finkelstein Julia L. , Rayco‐Solon Pura , Peña‐Rosas Juan Pablo , Garcia‐Casal Maria N. , Rogers Lisa , Ridwan Pratiwi , Martinez Sabrina Sales , Andrade Joyce , Layden Alexander J. , Chang Juan , Zambrano Mildred P. , Ghezzi‐Kopel Kate , Mehta Saurabh
Published: October 2020

To help inform global guidelines on infant feeding, this systematic review synthesizes evidence related to the presence of the Ebola virus (EBOV) in breast milk and its potential risk of viral transmission to the infant when breastfeeding. We relied on a comprehensive search strategy to identify studies including women with suspected, probable, or confirmed EBOV infection, intending to breastfeed or give breast milk to an infant. Our search identified 10,454 records, and after deduplication and screening, we assessed 148 full texts. We included eight studies reporting on 10 breastfeeding mothers and their children (one mother with twins), who provided breast milk samples for assessment. EBOV was detected via RT‐PCR or viral culture in seven out of ten breast milk samples. Four out of the five‐breastfed infants with EBOV‐positive breast milk were found positive for EBOV infection, and all of these EBOV‐positive infants died. Since previous reports have detected EBOV in tears, saliva, sweat, and contaminated surfaces, with the current evidence, it is not possible to conclude with certainty that breast milk was the main route of EBOV transmission.
Development and Validation of a Novel Scoring System for Severity of Plantar Fasciitis
Authors: Yin Meng‐chen , Yan Yin‐jie , Tong Zheng‐yi , Xu Chong‐qin , Qiao Jiao‐jiao , Zhou Xiao‐ning , Ye Jie , Mo Wen
Published: October 2020

Objectives

Plantar fasciitis (PF) is the most common cause of heel pain. Though PF is self‐limited, it can develop into chronic pain and thus treatment is needed. Early and accurate prognostic assessment of patients with PF is critically important for selecting the optimal treatment pathway. Nevertheless, there is no scoring system to determine the severity of PF and no prognostic model in choosing between conservative or surgical treatment. The study aimed to develop a novel scoring system to evaluate the severity of plantar fasciitis and predict the prognosis of conservative treatment.

Methods

Data of consecutive patients treated from 2014 to 2018 were retrospectively collected. One hundred and eighty patients were eligible for the study. The demographics and clinical characteristics served as independent variables. The least follow‐up time was 6 months. A minimal reduction of 60% in the visual analog scale (VAS) score from baseline was considered as minimal clinically important difference (MCID). Those factors significantly associated with achieving MCID in univariate analyses were further analyzed by multivariate logistic regression. A novel scoring system was developed using the best available literature and expert‐opinion consensus. Inter‐observer reliability and intra‐observer reproducibility were evaluated. The appropriate cut‐off points for the novel score system were obtained using receiver operating characteristic (ROC) curves.

Results

The system score = VAS (0–3 point = 1; 3.1–7 point = 3; 7.1–10 point = 5) + duration of symptoms (<6 months = 1; ≥1 6 months = 2) + ability to walk without pain (>1 h = 1; ≤1 h = 4) + heel spur in X‐ray (No = 0; Yes = 2) + high intensity zone (HIZ) in MRI (No = 0; Yes = 2). The total score was divided in four categories of severity: mild (2–4 points), moderate (5–8 points), severe (9–12 points), and critical (13–15 points). Inter‐observer agreement with a value of 0.84 was considered as perfect reliability. Intra‐observer reproducibility with a value of 0.92 was considered as perfect reproducibility. The optimum cut‐off value was 10 points. The sensitivity of predictive factors was 86.37%, 84.21%, 91.22%, 84.12%, and 89.32%, respectively; the specificity was 64.21%, 53.27%, 67.76%, 62.37%, and 79.58%, respectively; the area under curve was 0.75, 0.71, 0.72, 0.87, and 0.77, respectively. The Hosmer–Lemeshow test showed a good fitting of the score system with an overall accuracy of 90.6%.

Conclusions

Based on prognostic factors, the present study establishes a novel scoring system which is highly comprehensible, reliable, and reproducible. This score system can be used to identify the severity of plantar fasciitis and predict the prognosis of conservative treatment accurately. The application of this scoring system in clinical settings can significantly improve the decision‐making process.
Nurses' experiences of their decision‐making process when participating in clinical trials during the 2014–2016 West African Ebola crisis
Authors: Nguyen David , Arnaert Antonia , Pringle John , Ponzoni Norma , Kouyaté Sekou , Fansia Nahal , Nouvet Elysée
Published: October 2020

Objective

Due to the absence of a licenced vaccine or drug for treatment of Ebola patients during the 2014–2016 West Africa outbreak, frontline nurses were at increased risk of exposure. Hence, they were prioritized to participate in clinical trials to receive experimental therapeutics. To our knowledge no study has explored the nurses' experiences of their decision‐making process when volunteering in clinical trials using unproven agents, which is the purpose of this qualitative study.

Methods

This study, part of a larger Ebola study, thematically analyzed the interview data of nine nurses recruited from Sierra Leone, Guinea and Liberia; of which four joined a convalescent plasma trial and five a vaccine trial.

Results

In their decision‐making process to partake in a clinical trial, nurses identified two distinct decision points: the initial commitment followed by the point of no return when they presented themselves to participate. Each of these decisions were influenced by risk versus benefits calculations, and contextual factors.

Conclusion

Results showed the need for more health education and communication around the unproven agents in order for nurses to make informed decisions.
Increased expression of REV7 in small cell lung carcinomas and its association with tumor cell survival and proliferation
Authors: Sanoyama Itaru , Sakurai Yasutaka , Ichinoe Masaaki , Hoshino Akiyoshi , Kesen Yurika , Kato Takuya , Numata Yoshiko , Umezawa Atsuko , Jiang Shi‐Xu , Murakumo Yoshiki
Published: October 2020

REV7 is involved in multiple biological processes including DNA damage tolerance, cell cycle regulation and gene expression, and is an accessory subunit of the mutation‐prone DNA polymerase ζ. It has been reported that REV7 expression is associated with poor prognosis in several human cancers. The aim of this study is to investigate the significance of REV7 in lung carcinogenesis. Immunohistochemical analyses of surgically resected lung cancer specimens revealed that REV7 shows an increased expression in small cell lung carcinomas (SCLCs) when compared with other histological types of lung carcinoma. Association between REV7 expression levels and clinicopathological factors was investigated using SCLC cases with or without surgical resection. Our analyses revealed that high REV7 expression significantly correlated with tumor cell proliferation, assessed by Ki‐67 labeling indices, and was negatively associated with distant metastasis and extensive‐stage disease. No significant association was detected between REV7 expression and other factors, including prognosis or response to chemoradiotherapy in SCLC. Increase in REV7 expression in SCLC was confirmed using SCLC cell lines. In addition, siRNA‐mediated depletion of REV7 activated the apoptotic pathway and suppressed cell growth in SCLC cells. These results suggest that REV7 plays an important role in tumor cell survival and proliferation in SCLC.
Distribution of amyloidosis subtypes based on tissue biopsy site − Consecutive analysis of 729 patients at a single amyloidosis center in Japan
Authors: Abe Ryuta , Katoh Nagaaki , Takahashi Yusuke , Takasone Ken , Yoshinaga Tsuneaki , Yazaki Masahide , Kametani Fuyuki , Sekijima Yoshiki
Published: October 2020

This study was performed to elucidate the distribution of amyloidosis subtypes based on tissue biopsy site. Samples obtained from 729 consecutive patients with amyloidosis were analyzed by immunohistochemical staining (IHC) and supplemental mass spectrometry (MS). The correlations between the type of organs from which samples were obtained and amyloidosis subtypes were investigated retrospectively. Among the patients, 95.1% were diagnosed by IHC and 4.9% were diagnosed by MS. The distribution of amyloidosis subtypes was as follows: AL, 59.1%; ATTR, 32.9%; AA, 4.0%; AH, 1.4%; Aβ2M, 0.8%; and others, 0.9%. AL was the most common subtype in most organs, including the liver, lung, kidney, lower urinary tract, bone marrow, gastrointestinal tract, and skin/subcutaneous tissue. ATTR was the most common subtype in the heart, carpal tunnel, and peripheral nerves. AH was the second most common subtype in renal biopsy. Three or more amyloidosis subtypes were detected in each organ. In conclusion, AL was the most common subtype in most biopsy sites except the heart, carpal tunnel, and peripheral nerve, in which ATTR was more common. Because several types of amyloidogenic protein were detected in each organ, amyloid typing must be pursued, no matter the site from where biopsy was obtained.
Unveiling associations between ciliate parasites and bacterial microbiomes under warm‐water fish farm conditions – a review
Authors: Jahangiri Ladan , Shinn Andrew P. , Pratoomyot Jarunan , Bastos Gomes Giana
Published: October 2020

Intensive fish production has arguably resulted in a consequential increase in the incidence of disease within the aquaculture industry. The frequency and the severity of disease events are in part affected by changing global climatic conditions. More importantly, these changes directly influence changes in water quality parameters and the dynamics of a microbiome, pathogenic or not, in aquatic farming. Changes in temperature, for example, have both direct and indirect effects on the health status of fish, potentially increasing their predisposition to infections. In general terms, fish infections are rarely caused by a single agent or factor – frequently, multiple pathogens, changes in water quality parameters, production factors (e.g. feed quality, stocking density) and host immunity are concomitantly responsible for the establishment of infections in fish farms. Ciliate protozoans represent an important microfauna in aquatic environments. Ciliated protozoans can proliferate quickly, debilitating the host, and, in the absence of an intervention, can lead to a significant loss of stock. Ciliate infections frequently facilitate the establishment of secondary microbial species, both of which are linked to environmental and culture conditions. In this review, economically important ciliated protozoans of warm‐water cultured fish and their potential interactions with their associated bacterial microbiomes (both on/in their hosts and their surrounding environment) are discussed. Also, potential environmental triggers behind ciliate outbreaks within warm‐water aquaculture are reviewed. With better knowledge about such interactions, it will be possible to highlight innovative strategies to control ciliate parasites and bacterial infections in aquaculture.
Polarized Scientists? Exploring Political Differences about Religion and Science among U.S. Biologists and Physicists1
Authors: Mehta Sharan Kaur , Thomson Robert A. , Ecklund Elaine Howard
Published: October 2020

From the Texas textbook debate to the March for Science, visible displays of activism illuminate how deeply politicized the science‐religion interface has become. However, little is known about the extent to which scientists’ attitudes about science and religion are politicized. Using original survey data from 1,989 U.S. academic biologists and physicists, we examine the degree to which political views shape how scientists perceive the relationship between religion and science, religious authority, their personal religious identity, and views on dominant scientific theories. Findings suggest that, indeed, the science‐religion interface holds political meaning for scientists, but in different ways across the political spectrum. Specifically, for politically liberal scientists, atheism and the conflict narrative are particularly politicized belief structures, while politically conservative scientists emphasize religious identity to distinguish themselves from political liberals. Findings point to the critical role of politics in shaping scientists’ attitudes and identities, which may have implications for the scientific enterprise, both at the lab bench and in the political sphere.
The effect of air pollution on the skin colour and tone of Chinese women: A multicentre cohort study
Authors: Nkengne Alex , Robic Julie , Lua Bee Leng
Published: October 2020

Background

Overall facial skin colour is an important sign of perceived health and attractiveness, is predetermined by genetic factors, and is influenced by cultural and living habits, ultraviolet (UV) exposure, climate/seasons and ageing. The objective of this study was to determine the impact of pollution on the skin colour of Chinese women.

Materials and Methods

A total of 203 Chinese women between 20 and 59 years of age participated in the study and were selected from two cities with different levels of air pollution. Skin colour (L*, a* and b* values), melanin and haemoglobin levels were measured at three sites: the cheek, eye and inner upper arm. Measurements of the inner upper arm were taken as this area of skin was exposed to air pollutants but had minimal exposure to UV light.

Results

There were significant differences in skin chromophores between Chinese women living in two different cities with different levels of pollution. The b* value (yellowness) was higher in the eye and cheek region, and the a* value (redness) was lower in the cheek and arm region for women in the moderately polluted city. The melanin index was significantly higher, and the haemoglobin level was lower for the eye region for women living in the city with a higher level of air pollution.

Conclusion

This study has shown that air pollution may negatively affect the skin colour of Chinese women.
Depth‐resolved investigation of multiple optical properties and wrinkle morphology in eye‐corner areas with multi‐contrast Jones matrix optical coherence tomography
Authors: Yamazaki Kohei , Li En , Miyazawa Arata , Kobayashi Masaki , Sayo Tetsuya , Makita Shuichi , Takahashi Yoshito , Yasuno Yoshiaki , Sakai Shingo
Published: October 2020

Background

Multi‐contrast Jones matrix optical coherence tomography (JM‐OCT) can provide quantitative depth‐resolved local optical properties by improving the measurement algorithm.

Materials and methods

We examined the relationship between depth‐resolved local optical properties of eye‐corner skin measured by JM‐OCT and corresponding wrinkle morphology of aged women (n = 21; age range, 71.7 ± 1.7 years). Wrinkle morphology was analyzed by measuring the surface topography of three‐dimensional replicas. The same regions were measured three‐dimensionally by JM‐OCT, and the local optical properties at each depth were computed.

Results

Birefringence (BR) and mean wrinkle depth correlated significantly at a depth of 88.2‐138.6 µm from the skin surface, and attenuation coefficient (AC) and mean wrinkle depth correlated significantly at a depth of 12.6‐18.9 µm and 189‐459.9 μm from the skin surface, although a degree of polarization uniformity (DOPU) did not. Stepwise multiple regression analysis demonstrated that a significant regression equation (R2 = 0.649, P < .001) for predicting mean wrinkle depth was determined by BR at 107.1 µm depth (BR 107.1 µm), DOPU at 170.1 µm (DOPU 170.1µm), and AC at 252 µm (AC 252 µm) as independent variables and that these standardized beta regression coefficients were −0.860, −0.593, and −0.440, respectively, suggesting that BR, DOPU, and AC sufficiently explained mean wrinkle depth.

Conclusion

These results suggest that BR 107.1 µm, DOPU 170.1 µm, and AC 252 µm may indicate collagen‐related structure in the papillary, upper‐reticular dermis, and microstructure or tissue density in reticular dermis, respectively, and may be involved in wrinkle formation.
Ethylene‐activated PpERF105 induces the expression of the repressor‐type R2R3‐MYB gene PpMYB140 to inhibit anthocyanin biosynthesis in red pear fruit
Authors: Ni Junbei , Premathilake Apekshika T. , Gao Yuhao , Yu Wenjie , Tao Ruiyan , Teng Yuanwen , Bai Songling
Published: October 2020

Ethylene induces anthocyanin biosynthesis in most fruits, including apple (Malus domestica), strawberry (Fragaria × ananassa), and plum (Prunus spp.). However, ethylene inhibits anthocyanin biosynthesis in pear (Pyrus spp.), but the underlying molecular mechanism has not been characterized. In this study, ethylene induced the expression of PpERF105, which encodes a transcription factor. PpERF105 functioned as a transcriptional activator, but it inhibited anthocyanin biosynthesis in pear. A transcriptome analysis revealed that PpERF105 activated the expression of PpMYB140, which encodes an R2R3‐MYB transcriptional repressor. Moreover, PpMYB140 directly inhibited the expression of anthocyanin‐related structural genes. It also competed with PpMYB114 for the binding to bHLH3, ultimately resulting in the formation of the MYB140‐bHLH‐WDR complex rather than the conventional MBW complex, thereby further inhibiting anthocyanin biosynthesis. Furthermore, PpMYB140 prevented the overaccumulation of anthocyanins in the absence of ethylene. Collectively, our study data indicate that ethylene‐induced PpERF105 inhibits anthocyanin biosynthesis by upregulating PpMYB140 expression. Our findings may be useful for elucidating the molecular basis of the ethylene‐mediated inhibition of anthocyanin biosynthesis in fruit.
The Historical Evolution and Practical Experience of the Central Government's Strategy of Governing Hong Kong
Authors: Feng Qingxiang
Published: October 2020

The central government's strategy of governing Hong Kong is the policy and strategy used by the central government to govern Hong Kong, which as a whole reflects the central government's institutional arrangements, power and responsibility relations, policy trends and governance goals for Hong Kong. As a dynamic historical category, the central government's strategy of governing Hong Kong has gone through the arduous exploration of several generations of communists and accumulated rich practical experience, providing a direction guide for the development of "One country, Two systems". Since the founding of the People’s Republic of China, Mao Zedong’s strategy of “temporarily not intervening Hong Kong” has been embodied in the policy of “long-term planning and full utilization” of governing Hong Kong, which has important historical reference significance. Deng Xiaoping inherited and developed Mao Zedong's strategic thinking on the peaceful reunification of the country and put forward the scientific concept of "One country, Two systems", which was successfully applied in Hong Kong. Jiang Zemin and Hu Jintao further enriched and developed the policy of "One Country, Two Systems", opening a new chapter in Hong Kong's development. Xi Jinping did not forget the original intention of "One Country, Two Systems" and led the central government's strategy of governing Hong Kong into a new era.
Stress Analysis of SS316L Tube Die Expansion for High Pressure Gas Coolers
Authors: Zhao Zijian , Bouzid Abdel-Hakim
Published: October 2020

SS316L finned tubes are becoming very popular in high-pressure gas exchangers and particularly in CO2 cooler applications. Due to the high-pressure requirement during operation, these tubes require an accurate residual stress evaluation during the expansion process. Indeed, die expansion of SS tubes creates not only high stresses when combined with operation stresses but also micro-cracks during expansion when the expansion process is not very well controlled. This research work aims at studying the elastic-plastic behavior and estimating the residual stress states by modeling the die expansion process. The stresses and deformations of the joint are analyzed numerically using the finite element method. The expansion and contraction process is modeled considering elastic-plastic material behavior for different die sizes. The maximum longitudinal, tangential and contact stresses are evaluated to verify the critical stress state of the joint during the expansion process. The importance of the material behavior in evaluating the residual stresses using kinematic and isotropic hardening is addressed.
Crack Propagation Modeling in a PWR Under PTS Using XFEM
Authors: Mora Diego F. , Niffenegger Markus , Mukin Roman
Published: October 2020

The finite element simulation of fracture propagation of BCC metals is challenging, as it needs to incorporate the brittle, ductile-brittle transition and ductile behavior presented by the fracture toughness. In this contribution, we restrict ourselves to the use of XFEM method to simulate the cleavage fracture due to initial flaws in the reactor pressure vessel of a reference design of the two-loop PWR nuclear power plant. A hypothetical large break loss of coolant accident is selected as accident scenario to obtain the loading conditions under which the crack is subjected. The thermal-mechanical calculation is performed using a finite element model of the whole RPV and the initial and boundary conditions are determined from the thermal-hydraulic simulation of the transient in TRACE. The method proposed in this contribution is based on the cohesive segment approach implemented in ABAQUS, which requires the definition of the damage properties of the material. The segment approach does not use the fracture toughness as failure criterion. Instead, it uses a traction separation law that is able to capture the brittle fracture behavior of ferritic steel. The crack propagation in XFEM uses a propagation criterion based on a cohesive damage initiation criterion and a damage evolution model. In order to implement the damage evolution model, the fracture energy release rate is directly related to the fracture toughness. The postulated crack is inserted in a submodel to reduce the computational cost of the calculation. The location of such submodel corresponds to the region of the core that suffers maximum irradiation and is subjected to high tensile stresses due to the cooling plume generated during the transient PTS cooling. The crack propagation analysis of postulated axial crack showed that its propagation happens in axial direction in those finite elements close to the inner surface because the energy release rate GI is larger than the critical energy release rate GIC. At the deepest point of the crack, the stresses in the finite element fulfil the damage initiation criterion but the crack does not propagate in radial direction (GI < GIC).
A Comparative Study on the Sub-Model Method and the Local Model Method in the Tightness Analysis of Tube-to-Tubesheet Joints of Heat Exchanger
Authors: Zhang Xiangbing , Duan Chenghong , Luo Xiangpeng , Huang Jinhao
Published: October 2020

In the finite element analysis of large-scale heat exchangers, the tightness analysis of tube-to-tubesheet joints of heat exchanger is classified into a highly nonlinear problem due to the existence of contact between tube and tubesheet, and there are a large number of tubes in the heat exchanger. These all make it difficult to analyze the tube-to-tubesheet joints in detail with the full model method. The traditional local model method simplifies the problem in a certain extent, but its boundary condition is different from the actual situation, which will result in an inaccurate result. In this paper, the sub model method is introduced into the tightness analysis of tube-to-tubesheet joints of the heat exchanger. Taking a U-tube heat exchanger as an example, the traditional local model method and the sub model method are used to analyze the tightness of tube-to-tubesheet joints respectively. The residual contact pressure of the seal ring on the contact surface of tube-to-tubesheet joints is taken as the criterion to evaluate the tightness of the joint. Variations of the residual contact pressure obtained by the two methods are comparatively studied. It is found that the traditional local model method is not conservative enough compared with the sub model method, and the sub model method can simulate more real boundary condition and obtain tightness conditions of the joint in different locations,which is a more effective analysis method. In addition, it is found that the choice of cutting boundary of the sub model has certain influence on the analysis results.
Inspection Case Analysis of Natural Gas Manifold in a High Acid Gas Field
Authors: Wang Jielu , Song Wenming , Tang Xiaoying , Ding Ju , Pu Zhe
Published: October 2020

Natural gas manifold is one of the key production facilities in gas field. It is used to buffer, collect and distribute natural gas in natural gas station. In the gas gathering terminal station of a high acid gas field, one of the manifolds had cracks and leakage on the surface of longitudinal welds when it ran for less than 100 hours. Several tests had been carried out of the failure weld seam. Test results analyses and theoretical analysis show that the cracking may cause by weld defects and propagated rapidly based on the mechanism of hydrogen blisters and HIC. In order to verify the conclusion of the analyses and ensure the safe operation of the gas field, an overall inspection of all the natural gas manifolds in the gas field had been carried out. The inspection results proved that there were manufacturing defects in the weld of all the manifolds in this gas field. The natural gas manifold has great influence on the safe operation of natural gas field. The poor working condition of the manifold may lead to failure and even endanger the safety of production. The case analysis in this paper provides a reference for the manifold inspection and ensures the safe operation of the gas field.
Research on Digital Radiographic Inspection of In-Service Fiber Reinforced Plastic Pipe
Authors: Liu Shu H. , Ding Ju , Zhang Jian F.
Published: October 2020

With the development of material technology, non-metallic materials are applied to pressure pipes in petrochemical plant. Fiber reinforced plastic (FRP) is widely used because high mechanical strength and corrosion resistance. The non-metallic pipeline has been running for more than 20 years in petrochemical plant of China. Due to the fiber material anisotropy, it is difficult to measure thickness and detect defect by conventional ultrasonic method in FRP inspection. According to Chinese pressure pipeline inspection laws and regulations, the main inspection methods are macroscopic examination and hydraulic pressure test. The inspection of non-metallic pipelines has not been specified in detail. Compared with traditional radiographic detection, digital radiographic detection has better contrast and image processing technology, so digital radiographic detection has more advantages in thickness measurement and corrosion detection.

Elbows are most prone to corrosion defects due to fluid erosion. In this paper, fiber reinforced plastic pipe is detected by digital radiographic technology. In digital radiographic detection, appropriate parameters and accurate measurement are proposed. The accurate wall thickness of the pipe is obtained and the internal defects are detected. By comparing the measurement results with the actual wall thickness, the measurement accuracy of digital radiographic detection could meet the requirement of ultrasonic thickness gauge in NB/T47013.3. Digital radiographic technology is strongly recommended for FRP pipeline periodic inspection.
Structural Dynamic Modification of Cylindrical Shells With Variable Thickness
Authors: Mahboubi Nasrekani Farid , Shivneel Kumar Shymal , Narayan Sumesh
Published: October 2020

In this paper, the effects of some geometrical parameters on dynamic behavior of cylindrical shells with constant and variable thickness are studied. The equation of motion for the shell with constant thickness is extracted based on classical shell theory using Hamilton’s principle. These equations which are a system of coupled partial differential equations are solved analytically and the natural frequency is determined for cylindrical shells with constant thickness. The natural frequency for cylindrical shells with variable thickness is determined using finite element method by employing ANSYS. The results are compared and the effect of different geometric parameters such as length, thickness, and radius on natural frequency is discussed. The specific ranges for geometric parameters have been determined in which there is no significant difference between shells with constant or variable thickness. Cylindrical shells with variable thickness have better stress and strain distribution and optimum weight, in compare with the shells with constant thickness and it is important to know in which ranges of dimensions and geometrical parameters, there are some significant differences between their mechanical properties such as natural frequency. The results are compared with some other references.
Improved Method for Fracture Toughness Testing Using Compliance Method for High Toughness Materials
Authors: Kim Kuk-Cheol , Jeong Jae-Suk , Lee Choo-Won , Suk Jhin-Ik , Kwak Joo-Hwan
Published: October 2020

In order to ensure the integrity of structures such as gas turbines and nuclear power plants, the materials used should have excellent toughness. Especially in the case of nuclear piping materials applied to leak before break (LBB) design, high toughness materials are used to meet the stringent fracture toughness criteria and integrity must be verified through static J-R curve testing using the compliance method, one of the measurement techniques for fracture toughness. The measured and estimated values for the crack extension length during the test should also match, within a certain tolerance. However, in the case of materials with high toughness, rotation of the specimen becomes significant, because the test is performed until the crack open displacement (COD) is relatively large to ensure sufficient crack extension. In this case, it is not easy to satisfy these conditions due to the rotational effect on the specimen. Even though ASTM E1820 suggests a method for correcting the crack length for the rotational effect on these specimens, it has been found that there are substantial differences for high toughness materials. To solve this problem, a new crack length correction formula considering the rotation effect is proposed. Through analysis of the data from J-R curve testing with this proposed method, it was confirmed that the accuracy of crack extension length estimation is improved compared to the existing method. The proposed method well explains the variation of crack extension length due to rotation and is suitable as a correction equation for rotation of compact tension specimens.
Fatigue Life Prediction for Variable Strain at a Mixing Tee by Use of Effective Strain Amplitude
Authors: Miyoshi Koji , Kamaya Masayuki
Published: October 2020

Mixing flow causes fluid temperature fluctuations near the pipe walls and may result in fatigue crack initiation. The authors have previously reported the loading sequence effect on thermal fatigue in a mixing tee. The fatigue damage around the hot spot, which was heated by the hot jet flow from the branch pipe, obtained by Miner’s rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. In this study, the effect of a single overload on the fatigue crack growth rate was investigated in order to clarify the reduction of the fatigue life at the mixing tee due to strain with periodic overload. In addition, the prediction method of the fatigue life for the variable thermal strain at the mixing tee was discussed. It was shown the crack growth rate increased after an overload for both cases of tensile and compressive overloads. The effective strain amplitude increased after the application of a single overload. The fatigue life curve was modified by considering the increment of the effective strain range. The fatigue damage recalculated using the modified fatigue life curve was larger than 1.0 except in a few cases. The fatigue life could be assessed conservatively for variable strain at the mixing tee using the developed fatigue curve and Miner’s rule.
Mechanical Properties and Microstructure of the Newly Developed Steel (Low C 18Cr-11Ni-3Cu-Mo-Nb-B-N) After Aging Treatment
Authors: Otaki Nao , Hamaguchi Tomoaki , Osuki Takahiro , Suzuki Yuhei , Ueyama Masaki , Okada Hirokazu
Published: October 2020

In petroleum refinery plants, materials with high sensitization resistance are required. 347AP has particularly been developed for such applications and shows good sensitization resistance owing to its low C content. However, further improvement in high temperature strength is required for high temperature operations in complex refineries, such as delayed cokers. Recently, a new austenitic stainless steel (low C 18Cr-11Ni-3Cu-Mo-Nb-B-N, UNS No. S34752) with high sensitization resistance and high strength at elevated temperatures has been developed. In this study, the mechanical properties and microstructures of several aged specimens will be reported. By conducting several aging heat treatments in the range of 550–750 °C for 300–10,000 h on the developed steel, it was revealed that there were only few coarse precipitates that assumed sigma phase even after aging at 750 °C for 10,000 h. This indicates that the newly developed steel has superior phase stability. The developed steel drastically increased its Vickers hardness by short-term aging treatments. Through transmission electron microscopy observations, the fine precipitates of Cu-rich phase were observed dispersedly in the ruptured specimen. Therefore, the increase in Vickers hardness in short-term aging is possibly owing to the dispersed precipitation of Cu-rich phase. There was further increase in Vickers hardness owing to Z phase precipitation; however, the increment was smaller than that caused by Cu-rich phase. The newly developed alloy demonstrated excellent creep rupture strength even in the long-term tests of approximately 30,000 h, which is attributed to these precipitates.
An Estimation of Long-Term Sealing Performance for Bolted Pipe Flange Connections With Spiral Wound Gaskets Under Elevated Temperature
Authors: Sato Koji , Sawa Toshiyuki
Published: October 2020

SWGs (Spiral Wound Gaskets) are well known as a most used gasket type in bolted pipe flange connections all over the world. Recently, the connections with SWGs have been used under more severe conditions such as higher temperature and pressure, and in addition, the connections have been used in the more long-term application. Thus, it is necessary for plant owners (gasket users) to know the long-term characteristics of the connections with SWGs from a standpoint of integrity in the connections. In this study, the objective is to establish a long-term estimation method of sealing performance for bolted pipe flange connections with SWGs under elevated temperature. The long-term characteristics of pipe flange connections with SWGs are estimated using FEM calculations in which the fundamental mechanical characteristics of SWGs such as compression property under changed temperature is considered, thermal expansion behavior, creep relaxation and sealing performance are taken into considerations. For verification of FEM calculations, the experiments are carried out for the pipe flange connections with SWGs of which the nominal size is ASME class 300 2inch under elevated temperature and internal pressure. The gasket used is chosen as SWG with flexible graphite filler. The change in axial bolt forces and an amount of leakage are measured and the measured results are fairly coincided with the FEM calculation results. In addition, the contact gasket stress in the connection with SWG is shown in 72 months. The FEM calculations are performed as heat conduction problem in transient state.
The Comparison of the Criteria for Ratcheting in ASME VIII-2 and Methods Given by C-TDF
Authors: Wan Liping , Dong Wangping
Published: October 2020

Ratcheting assessment by elastic-plastic stress analysis is presented in ASME VIII-2, paragraph 5.5.7. There are three criteria. The first one is strict in engineering design. It’s hard for most of structures to satisfy it. If the plastic strain in the structure is zero, it means that the material is not fully utilized and maybe the structure is unreasonable. Therefore, the second and third criteria are used much more. The first one and the third one can be observed directly and judged accurately by the finite element analysis results. The second one demands an elastic core in the primary-load-bearing boundary. It could be easily observed when the structure is axisymmetric, but hard to judge in the 3D structure.

Okamoto in Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) has studied two thermal stress ratchet criteria: evaluating variations in the plastic strain increments and evaluating variations in the elastic core region, which can accurately assess ratcheting. Recent years, based on the criteria above, more researches have been performed by engineers not only from C-TDF but from all over the world.

In this work, several two-dimensional structures and three-dimensional structures under particular load and displacement boundaries are performed by using finite element software ANSYS, aiming to compare the similarities and differences between the criteria in ASME VIII-2, 5.5.7.2 and those given by C-TDF. The assessment of these structures presented in this work will help engineers understand the realization of the criteria and methods in engineering design, especially how to utilize the results from ANSYS.
Application of a Novel Crack Mouth Opening Displacement Partitioning Technique to Creep Crack Growth Tests on SEN(T) Geometries of Type 316H Stainless Steel
Authors: de Andres Jorge , Jones Michael D. , Davies Catrin M.
Published: October 2020

A new technique has recently been proposed to provide improved estimates of the creep contribution to the crack mouth opening displacements (CMOD) and displacement rates during creep crack growth (CCG) tests. This technique employs finite element analysis that incorporates material specific uniaxial tensile test data to simulate crack growth in an experimental test and can account for strain history and creep stress relaxation effects during CCG tests. In this work, this new methodology is applied to analyse the results of a CCG test performed on a relatively low constraint single edge notched tension, SEN(T), geometry. The proportions of the CMOD due to elasticity and plasticity are quantified, and compared to historic, standardised methods of estimating these values. The new method reduces the over estimation of the contribution of plasticity to the CMOD measurement. The impact of this analysis on CCG test results is discussed.
A Novel Assessment Method for Wrinkle Defects in Composites
Authors: Shen Chuanchuan , Ma Li , Zheng Jinyang
Published: October 2020

Fiber reinforced composite structures have been increasingly used in the field of pressure vessels and piping. Various process-induced defects of composite structures are accumulated during their manufacture processes for the variations of environment temperature and humidity, pre-stress of fiber and curing temperature. Wrinkle defect is one of the most frequently encountered defects in fiber reinforced composite structures. In this paper, a new method for detecting wrinkle defects based on the relation of the displacement fields between flawed and flawless areas is proposed. The orthotropic finite element analysis codes combined with wrinkle model were developed based on Matlab platform to predict structural responses of laminates under three different loading types, including transverse compression, axial tension and bending. The effective elastic moduli disturbed by wrinkles were determined based on a mesomechanics model and a two-step homogenization procedure. Two different wrinkle models including definite and heterogeneous distributed models were considered. It is found that the out-of-plane displacement obviously increases at the wrinkle region under the axial load. The fluctuant displacement fields under axial tensile load can be clearly observed when the heterogeneity wrinkle model is considered. However, the transverse compression cannot produce any displacement distortion. All the results bring us a new idea of non-destructive evaluation for composites, wherein the defects that mainly weakening the stiffness can be detected by measuring the displacement distribution under some specified loads.
Dynamic Analysis of Liquid Sloshing for Shipboard Pressure Vessel
Authors: Li Qi , Tang Hui , Zhang Fujun , Wang Zhijian , Shi Qianyu
Published: October 2020

With the development of pressure vessel industry in China, more and more pressure vessel is widely used in the aerospace, automobile, marine project and other fields. The liquid sloshing in the device could bring adverse effect on the safety operation of the pressure vessel under the extrinsic excitation, such as the impact load results in the failure of device structure. Thus, dynamic analysis of liquid sloshing for the shipboard pressure vessel is significant. According to the little research on the design criteria and the method of the shipboard pressure vessel, this paper focuses on the research of the transient sloshing of the internal liquid in the shipboard pressure vessel. In this paper, during analyzing the liquid sloshing dynamic of the shipboard pressure vessel, an obvious cycle is got. Considering the operation condition of lateral inclination, longitudinal inclination and heave in the complex marine environment, the liquid sloshing character is obtained and compared through the liquid surface height curve and the wall sloshing pressure curve, which has great influence on the piping layout of the pressure vessel. Moreover, it is beneficial to restrain sloshing through installing baffle inside the pressure vessel. This may provide a project reference to liquid sloshing design of the shipboard pressure vessel.