Degree Of Expansion Research Articles

Expansionary Fiscal Policy, Corporate Governance and Corporate Value

Among expansionary fiscal policy, corporate governance and corporate value, fiscal policy plays a unique influencing factor in the social organization as well as internal structure of countries with different levels of economic development. Such as the nature of different equity and governance characteristics, macro policy efficiency for firms and fiscal deficits. To measure the combined impact of fiscal policy expansion on corporate value, the governance structure of a firm is inextricably linked to the value of the firm itself if it is to be effective. The value of the company is reflected in the nature of equity and the management structure of the management. It is found that the higher the degree of fiscal policy expansion in the region to which the company belongs, the higher the value of the company itself. In terms of the marginal effect of fiscal policy, non-state owned companies are significantly stronger than state owned companies. State-owned enterprises are relatively weak and deficient in the efficiency of using funds to create valuable. Thus, analyzing the moderating role of corporate governance factors, it is clearly known that corporate management and corporate equity checks and balances can better ensure that companies can efficiently accomplish fiscal policy and create a reasonable value system.

Experience with Optical Coherence Tomography Enhanced by a Novel Software (Ultreon™ 1.0 Software)-The First One Hundred Cases.

Introduction: Optical coherence tomography (OCT) intravascular imaging including the latest version Ultreon™ 1.0 Software (Abbott Vascular, Santa Clara, CA, USA), not only improve patients prognosis, but also facilitates improved percutaneous coronary intervention (PCI). Objectives: The aim of the study was to compare procedure related decision making, procedural indices, clinical outcomes according to the extent of stent expansion and assess risk factors of underexpansion in patients treated with PCI using OCT. Methods: The study comprised 100 patients, which were divided in groups according to the extent of stent expansion: <90 (29 patients) and ≥90% (71 patients). Comparison of OCT parameters, selected clinical and procedural characteristics was performed between groups. We assessed clinical outcomes during the follow-up: major adverse cardiovascular events and risk factors of stent underexpansion. Results: Patients from the stent underexpansion group were treated more often in the past with percutaneous peripheral interventions (p = 0.02), no other significant differences being noted in general characteristics, procedural characteristics or clinical outcomes comparing both groups. Significant predictors of stent underexpansion assessed by simple linear univariable analysis included: hypercholesterolemia, obstructive bronchial diseases and treatment with inhalators, family history of cardiovascular disease, PCI of other than the left main coronary artery, stent and drug-eluting stent implantation, PCI without drug-eluting balloon, paclitaxel antimitotic agent, greater maximal stent diameter and lower mean Euroscore II value. Univariable logistic regression analysis revealed a correlation between stent underexpansion and greater creatinine serum concentration before [OR: 0.97, 95%CI: 0.95–0.99, p = 0.01)] and after PCI [OR: 0.98, 95%CI: 0.96–0.99, p = 0.02)]. Conclusions: Based on the presented analysis, the degree of stent expansion is not related to the selected procedural, OCT imaging indices and clinical outcomes. Logistic regression analysis confirmed such a relationship for creatinine level.

Adsorption properties of templated nanoporous carbons comprising 1–2 graphene layers

Various types of vapor adsorption (water, methanol, ethanol, dichloromethane, and n-hexane) were examined on templated nanoporous carbons comprising 1–2 graphene layers, e.g., microporous zeolite-templated carbon (ZTC), mesoporous carbon mesosponge (CMS), and graphene mesosponge (GMS). Conventional nanoporous carbon materials are used as references. Although water-vapor adsorption is unique owing to the repulsion between H2O molecules and hydrophobic carbon, organic-vapor adsorption follows a typical physisorption mechanism. Graphene-based nanoporous materials exhibit an evident degree of adsorption-induced expansion based on their extraordinary softness, except in the case of inferior water-vapor adsorption on mesoporous CMS and GMS. CMS exhibits a considerable degree of adsorption-induced expansion and can achieve high adsorption capacities up to 4.25–4.76 cm3 g−1 for organic vapors, demonstrating its feasibility as a high-capacity adsorbent. The adsorption isotherms of ZTC at 278 and 298 K for n-hexane overlap well, which is advantageous for a new heat pump working with a force-induced phase transition. Moreover, this study helps predict the ease of organic-vapor adsorption based on the product of the surface tension and molar volume.

Deformation and seepage properties of raw coal during the simultaneous loading and unloading of axial stress and confining pressure

The mining of coal resources causes the stress on the front and both sides of the working face to be in a complex loading and unloading process, and the gas contained in the coal body migrates, which can cause gasdynamic disasters in severe cases. Therefore, this study designed a three-dimensional stress path based on the in situ stress distribution characteristics of the No. 2461 working face and conducted the experiment on the deformation and seepage characteristics of raw coal under simultaneous unloading (loading) axial stress and loading (unloading) confining pressure. It is considered that in the process of loading axial stress, the volumetric strain increases gradually with the increase in effective stress, and the permeability decreases exponentially with the increase in effective stress. In the process of simultaneous unloading axial stress and loading confining pressure, the volumetric strain of coal sample increases with the increase in effective stress, and the permeability decreases exponentially with the increase in effective stress. However, the processes of simultaneous loading axial stress and unloading confining pressure are opposite, and the variation curves of the two do not overlap, indicating that the coal sample undergoes elastic-plastic deformation after cyclic loading, the permeability cannot be restored to the initial state, and the volumetric strain further expands. The permeability damage rate and maximum permeability damage rate are used to evaluate the recovery degree and reduction range of coal samples' permeability. The volume expansion rate and maximum volume expansion rate are used to evaluate the expansion degree and increase range of coal samples' volume.

Research on expansion and stability of Friedel’s salt

Friedel’s salt is a common hydrate of cement concrete in chloride environment, and the change of its performance will affect the performance of cement paste and the safety of concrete structure. In order to study the properties and morphological characteristics of Friedel’s salt, Friedel’s salt is prepared by reaction of C3A with chlorine salt and chemical synthesis in this paper. The expansibility and stability of Friedel’s salt are studied by XRD, SEM, TG-DTG and FTIR. The results show that the higher the curing temperature is, the faster the reaction rate is, the expansion degree is 0.3 and the density is 2.087 g/cm3. Friedel’s salt is more stable in alkaline environment, and the greater the pH value is, the more stable the Friedel’s salt is. Under dry heat curing, Friedel’s salt is gradually decomposed with the increase of temperature, and the Friedel’s salt prepared by C3A and chlorine salt is completely decomposed at 500 °C, and the Friedel’s salt prepared by chemical method is completely decomposed at 600 °C. Under damp heat curing, Friedel’s salt is gradually decomposed with the increase of temperature, and it is not completely decomposed at 100 °C.

Raman Spectroscopy as Spectral Tool for Assessing the Degree of Conversion after Curing of Two Resin-Based Materials Used in Restorative Dentistry.

(1) Background: The treatment of dental cavities and restoration of tooth shape requires specialized materials with specific clinical properties, including being easy to model, light-cured, having a natural color, reduced shrinkage, a hardness similar to hydroxyapatite, and no leakage. The dimensional stability of resin composite materials is affected by polymerization shrinkage, degree of conversion (number of π carbon bonds converted into σ ones), thermal contraction and expansion, and interactions with an aqueous environment. (2) Methods: The materials used in our investigation were two composite resins with similar polymer matrices, but different filler (micro/nano filler). To evaluate the properties of samples, we employed the pycnometer technique (pycnometer from Paul Marienfeld Gmbh, Lauda-Königshofen, Germany), RAMAN spectroscopy technique (MiniRam Equipment from B&W Tek Inc., Plainsboro Township, NJ, USA; 785 nm laser source), SEM and EDX (FEI Inspect S.). (3) Results: The size of the filler plays an important role in the polymerization: for the pycnometric results, the larger particle filler (Sample 1) seems to undergo a rapid polymerization during the 45 s curing, while the nanoparticle filer (Sample 2) needs additional curing time to fully polymerize. This is related to a much larger porosity, as proved by SEM images. The lower degree of conversion, as obtained by Raman spectroscopy, in the same geometry means that the same volume is probed for both samples, but Sample 1 is more porous, which means less amount of polymer is probed for Sample 1. (4) Conclusions: For the two composites, we obtained a degree of conversion of 59% for Sample 1 and 93% for Sample 2, after 45 s of curing.

Precise prediction of photothermally induced irreversible bending deformation based on non-uniform thermal expansion of layer-structure films

Although photothermally induced self-bending films based on nonuniform thermal expansion are created, heat transfer and shape-deformation procedures are not investigated very well, limiting the understanding of such complicated behavior and the achievement of precise shape control. Here, thermally expanded microspheres (TEMs) were added into polydimethylsiloxane (PDMS) to create active layers as PDMS-TEM single-layer films that were attached onto pure PDMS passive layer to create PDMS/PDMS-TEM bi-layer films subsequently. After heating, TEMs in the film undergo phase transition and present irreversible thermal expansion, driving deformation of films. Combined with steady-state (uniform heating) deformation simulations and experiments, a deformation model was established before a non-steady state (light irradiation) heat transfer model was set up to simulate the heat transfer process of films under light irradiation. Then the temperature distribution was coupled with the deformation model to simulate the photothermally induced deformation of the samples. The PDMS-TEM single-layer films also presented bending deformation under illumination due to the non-uniform thermal expansion caused by temperature gradient. For bi-layer films, different degrees of thermal expansion between two layers lead to bending deformation. The films with TEM concentration of 30 wt% can achieve great deformation, and the bending curvature was 0.07 mm−1. The geometric parameters including thickness, layer thickness ratio and aspect ratio had little effect on deformation degrees of the films. Deformation mode was varied with aspect ratio. A long side bending and diagonal bending were achieved in bi-layer films at aspect ratios of 7:1 and 1:1. In combination with experimental results, the heat transfer model and deformation model were constructed to demonstrate the complex deformation process, which provides guidance for the structural design of the photothermally induced shape-changing films in practical applications.

Evolution of global development cooperation: An analysis of aid flows with hierarchical stochastic block models.

Despite considerable scholarly attention on the institutional and normative aspects of development cooperation, its longitudinal dynamics unfolding at the global level have rarely been investigated. Focusing on aid, we examine the evolving global structure of development cooperation induced by aid flows in its entirety. Representing annual aid flows between donors and recipients from 1970 to 2013 as a series of networks, we apply hierarchical stochastic block models to extensive aid-flow data that cover not only the aid behavior of the major OECD donors but also that of other emerging donors, including China. Despite a considerable degree of external expansion and internal diversification of aid relations over the years, the analysis has uncovered a temporally persistent structure of aid networks. The latter comprises, on the one hand, a limited number of major donors with far-reaching resources and, on the other hand, a large number of mostly poor but globally well-connected recipients. The results cast doubt on the efficacy of recurrent efforts for “aid reform” in substantially changing the global aid flow pattern.

Numerical analysis of two-stage vacuum ejector performance considering the influence of phase transition and non-condensable gases

Multi-effect distillation with thermal vapor compression system has not been able to penetrate the market because of the low coefficient of performance. The two-stage vacuum ejector is an effective vehicle to maintain system condensing temperature, discharge non-condensable gases and improve the system performance. Improving performance of two-stage vacuum ejector relies on the understanding of the fluid dynamic phenomena. Unfortunately, few studies paid attention to the effect of inner fluid phase transition and non-condensable gas mass fraction on the performance of vacuum ejector. Therefore, this paper contributes to proposing a Species transport and Phase transition model to investigate the two-stage vacuum ejector numerically considering the physical properties of non-condensable gases, thermodynamic transformation caused by condensation and evaporation with experimental validation. The results indicate that the entrainment performance of the ejector increases by about 14.95% when the non-condensable gases mass fraction increases from 0% to 100%. Meanwhile, with the consideration of heat and mass transfer in the phase change process, the mean error is 4.9%, which is much lower than single-phase model. Meanwhile, the internal fluid pressure, Mach number, shock waves and expansion degree can be largely influenced by the consideration of Species transport and Phase transition. The results of this paper proved that influence of non-condensable gases and phase transition cannot be ignored in the design and prediction of vacuum ejector and it can contribute to ejector optimization and enhancing the stability and efficiency of multi-effect distillation with thermal vapor compression system.

Study of synthesis parameters on the physical properties and morphology of smart PNIPAAm hydrogels

Abstract Bone loss is common in human old age and new materials that promote bone regeneration are an active line of research. In the present work, seven smart hydrogels based on PNIPAAm were synthesized with the prospective to be used in tissue engineering as a scaffold for bone growth. By changing the stoichiometric concentrations of the reagents and the synthesis parameters, hydrogels with different physical properties and morphology were obtained. Swelling, degradation properties, and crystallinity were analyzed. Physical properties were characterized using 1H-NMR, FTIR, and TGA. The results showed that the swelling degree (degree of mass expansion) varied at room temperature from 1,400% for less rigid hydrogels to 550% for stiffer hydrogels. With heating to body temperature, swelling decreases to 300% and 200%, respectively. The samples presented three-dimensional morphology, but they acquired different structures according to the magnetic stirring during the synthesis process. The crosslink and initiator concentrations have an important effect on the polymeric structure and thermal stability of the hydrogels. The PNIPAAm synthesized using 8.9 and 15.7 mol % of MBA are the most promising compounds to be used in the future as a scaffold for biomedical applications due to their high thermal stability, satisfactory 3D surface morphology, and shrinking-swelling property.

PROBABLE JUVENILE FRONTAL OF DASPLETOSAURUS HORNERI (DINOSAURIA: THEROPODA) FROM THE TWO MEDICINE FORMATION OF MONTANA, WITH IMPLICATIONS FOR TYRANNOSAURID ONTOGENY

A partial left frontal (UCM 55499) of a small tyrannosaurid theropod from the Campanian Two Medicine Formation of Montana is described, and is considered to probably represent a juvenile of Daspletosaurus horneri. UCM 55499 compares favorably with the frontals of other young juvenile tyrannosaurid specimens, and its diminutive size suggests that the element comes from a small juvenile individual. Differences (including width of the nasal process, and degree of expansion of the postorbital buttress and the caudal shelf) between it and frontals of the larger individuals of Daspletosaurus horneri are similar to those between juveniles and adults of other tyrannosaurids such as Tyrannosaurus rex, suggesting that overall ontogenetic trends in the frontal bone of Daspletosaurus horneri are largely consistent with the patterns seen in other tyrannosaurids.

Analysis of Gene Expression and TCR/B Cell Receptor Profiling of Immune Cells in Primary Sjögren's Syndrome by Single-Cell Sequencing.

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease that is estimated to affect 35 million people worldwide and is characterized by lymphocytic infiltration, elevated circulating autoantibodies, and proinflammatory cytokines. The key immune cell subset changes and the TCR/BCR repertoire alterations in pSS patients remain unclear. In this study, we sought to comprehensively characterize the transcriptional changes in PBMCs of pSS patients by single-cell RNA sequencing and single-cell V(D)J sequencing. Naive CD8+ T cells and mucosal-associated invariant T cells were markedly decreased but regulatory T cells were increased in pSS patients. There were a large number of differentially expressed genes shared by multiple subpopulations of T cells and B cells. Abnormal signaling pathways, including Ag processing and presentation, the BCR signaling pathway, the TCR signaling pathway, and Epstein-Barr virus infection, were highly enriched in pSS patients. Moreover, there were obvious differences in the CD30, FLT3, IFN-II, IL-1, IL-2, IL-6, IL-10, RESISTIN, TGF-β, TNF, and VEGF signaling networks between pSS patients and healthy controls. Single-cell TCR and BCR repertoire analysis showed that there was a lower diversity of T cells in pSS patients than in healthy controls; however, there was no significant difference in the degree of clonal expansion, CDR3 length distribution, or degree of sequence sharing. Notably, our results further emphasize the functional importance of αβ pairing in determining Ag specificity. In conclusion, our analysis provides a comprehensive single-cell map of gene expression and TCR/BCR profiles in pSS patients for a better understanding of the pathogenesis, diagnosis, and treatment of pSS.

The effects of the cold expansion degree on the fatigue crack growth rate in rail steel

This study investigates the effects of the cold-expansion degree on the fatigue strength of rail steels. Two degrees of cold-expansion, 2% and 4%, and two stress levels were investigated. Results indicate that cold-expansion postpones crack initiation and extends fatigue life, especially with higher degrees of cold-expansion and lower stress levels. Linear superposition principle coupled with the weight function method results in an overestimated fatigue life of cold-expanded specimens, suggesting that reliable predictions can be achieved if both the residual stresses redistribution due to propagating crack and the crack closure effects due to plastic wake generation are considered in the simulations.

Development and application of a next-generation sequencing protocol and bioinformatics pipeline for the comprehensive analysis of the canine immunoglobulin repertoire.

Profiling the adaptive immune repertoire using next generation sequencing (NGS) has become common in human medicine, showing promise in characterizing clonal expansion of B cell clones through analysis of B cell receptors (BCRs) in patients with lymphoid malignancies. In contrast, most work evaluating BCR repertoires in dogs has employed traditional PCR-based approaches analyzing the IGH locus only. The objectives of this study were to: (1) describe a novel NGS protocol to evaluate canine BCRs; (2) develop a bioinformatics pipeline for processing canine BCR sequencing data; and (3) apply these methods to derive insights into BCR repertoires of healthy dogs and dogs undergoing treatment for B-cell lymphoma. RNA from peripheral blood mononuclear cells of healthy dogs (n = 25) and dogs newly diagnosed with intermediate-to-large B-cell lymphoma (n = 18) with intent to pursue chemotherapy was isolated, converted into cDNA and sequenced by NGS. The BCR repertoires were identified and quantified using a novel analysis pipeline. The IGK repertoires of the healthy dogs were far less diverse compared to IGL which, as with IGH, was highly diverse. Strong biases at key positions within the CDR3 sequence were identified within the healthy dog BCR repertoire. For a subset of the dogs with B-cell lymphoma, clonal expansion of specific IGH sequences pre-treatment and reduction post-treatment was observed. The degree of expansion and reduction correlated with the clinical outcome in this subset. Future studies employing these techniques may improve disease monitoring, provide earlier recognition of disease progression, and ultimately lead to more targeted therapeutics.

P-195 Do the presence of necrotic foci and/or separate blastomeres, the blastocoele expansion degree affect pregnancy outcomes of frozen-thawed euploid blastocysts transfer cycles?

Abstract Study question Do the presence of necrotic foci and/or the presence of separate blastomeres and the blastocoele expansion degree affect pregnancy outcomes of frozen-thawed euploid embryo transfer cycles? Summary answer Significant correlations were observed between pregnancy outcomes and the degree of blastocoele expansion, the presence of necrotic foci or separate blastomeres in the euploid embryo. What is known already Implantation failure and pregnancy losses may occur despite the selection of a healthy euploid embryo for transfer and the elimination of other risk factors. Blastocyst morphology is known to affect pregnancy outcomes, but the effect of necrotic foci and/or separate blastomeres in the embryo on pregnancy outcomes needs further investigation. Study design, size, duration This is a retrospective cohort study and was conducted at ART and Reproductive Genetics Centre, Memorial, Sisli Hospital, Istanbul, Turkey between January 2017 and September 2021. A total of 2758 frozen-thawed euploid embryo transfer cycles were included in the study. Participants/materials, setting, methods After thawing, the embryos were divided into groups according to their morphological grades, whether there were necrotic foci and whether there were separate blastomeres, and were evaluated in terms of pregnancy outcomes. Blastocysts were graded by using Gardner and Schoolcraft’s grading system. Ongoing pregnancy was defined as a pregnancy that had reached 20 weeks. Miscarriage was defined as a pregnancy loss occurring before the 20th gestational week. Main results and the role of chance Our data showed that the presence of necrotic foci in the inner cell mass or trophectoderm reduced the ongoing pregnancy rates and increased the miscarriage rates. The ongoing pregnancy rate was lower (41.0%, vs 60.0%, p &amp;lt; 0.001) and the miscarriage rate was higher (27.3% vs 19.8%, p &amp;lt; 0.05) in the group with necrotic foci than in the group without necrotic foci. The presence of separate blastomeres decreased the ongoing pregnancy rates (50.3% in the group with separate blastomeres, 61.8% in the group without separate blastomeres) (p &amp;lt; 0.001) and increased the miscarriage rates (25.3% in the group with separate blastomeres, 18.8% in the group without separate blastomeres) (p &amp;gt; 0.004). The ongoing pregnancy rates for blastocoele expansion degrees of 2, 3, 4, 5, and 6 were 39.5%, 38.3%, 59.3%, 59.8%, and 61.4%, respectively and the miscarriage rates for blastocoele expansion degrees of 2, 3, 4, 5, and 6 were 35%, 33.3%, 21%, 21.2%, 18.4%, respectively. Embryos with degrees of expansion grade ≤ 3 had lower ongoing pregnancy rates and higher miscarriage rates than those with degrees of expansion &amp;gt; 3 (p &amp;lt; 0.01). Limitations, reasons for caution Retrospective study. Wider implications of the findings When choosing the embryo to be transferred in cases with more than one euploid embryo, the selection should be made by considering the blastocoele expansion degrees and the presence of necrotic foci and separate blastomeres in the embryo. Trial registration number not applicable

P-133 The best of the worst: analyze of outcome in artificial reproductive technologies (ART) fresh cycles with transfers of slow-growing embryos and expanded poor-quality blastocysts

Abstract Study question Fresh transfer of slow-growing embryos versus expanded poor-quality blastocysts, in case of absence of good-quality blastocysts on day 5: which is the optimal approach? Summary answer The clinical pregnancy rate (CPR), live birth rate (LBR) are significantly higher during expanded poor-quality blastocysts transfers. There’s no statistical difference in miscarriage rate (MR). What is known already Several studies show contradictory results about which blastocyst morphological parameter best predicts pregnancy outcomes in ART cycle. However, in clinical practice embryologists encounter in ART protocols with scheduled fresh embryo transfer the absence of expanded good-quality blastocysts on day 5. In this case, slow-growing embryos or poor-quality blastocysts could be chosen for transfer. Day 5 slow-growing embryos have low implantation potential in fresh ART cycles, it could be due to embryo-endometrial asynchrony. Also, the quality of further blastocyst remains unclear. Poor-quality blastocysts have a high aneuploidy rate and lower viability compared to good-quality blastocysts. Study design, size, duration This study included ART cycles with fresh embryo transfer on day 5, with selected group of patients under 40 years of age, between 2014 and 2019. Group A consisted of 619 cycles with slow-growing embryos transfer; group B included 88 cycles with expanded poor-quality blastocysts transfer; the control group counted 1501 cycles with a transfer of good-quality blastocysts. Group A had an average of 1,5 embryos transferred per patient, control group and group B 1,3. Participants/materials, setting, methods Embryos were cultured until day 5 and scored according to Gardner and Schoolcraft’s grading system. In group A, slow-growing embryos were transferred at the stage of morula and early blastocyst with a degree of expansion 1. In group B, expanded poor-quality blastocysts were scored as 3-6CB, 3-6BC, 3-6CC. In control group expanded good-quality blastocysts were scored as 3-6AA, 3-6AB, 3-6BA, 3-6BB.The cycles with donor gametes, surrogacy, and preimplantation genetic testing were excluded. Main results and the role of chance The main women’s age of group A, B and control group was 32,2 ± 4,2, 31,5 ± 4,7 and 32,6 ± 4,6 years respectively. The CPR, the ongoing pregnancy rate (OPR), the LBR and the implantation rate (IR) were significantly increased in the group B compared to the group A [34,0% (30/88) vs 17,7% (110/619); P &amp;lt; 0,01], [21,6% (19/88) vs 11,9% (74/619); P = 0,012], [19,3% (17/88) vs 10,5% (65/619); P = 0,015] and [26,2% (31/118) vs 12,6% (119/946); P &amp;lt; 0,01] respectively. There’s no statistical difference in the MR between group A and B [35,2% (42/119) vs 35,5% (11/31); P = 0,946]. The CPR, the OPR, the LBR and the IR were significantly higher in the control group compared to the group A and B [50,5% (758/1501); P &amp;lt; 0,01], [41,6% (625/1501); P &amp;lt; 0,001], [40,3% (605/1501); P &amp;lt; 0,001] and [40,45% (849/2099); P &amp;lt; 0,01]. The MR in the control group was almost two times lower compared to the group A and B [16,2% (138/849); P &amp;lt; 0,01). Relationships between variables were assessed by Pearson's chi-squared test. Limitations, reasons for caution The study is limited due to the uneven distribution of patients in three groups and by a low number of participants in group B. The grading of blastocysts’ quality is also subjected to a human factor. Wider implications of the findings If in ART protocol with scheduled fresh embryo transfer have no expanded good-quality blastocysts, expanded poor-quality blastocysts could be chosen for transfer and slow-growing embryos should be cultured until day 6 with subsequent cryopreservation of blastocysts. Patients should be informed about elevated MR after the transfer of poor-quality blastocysts. Trial registration number Not applicable

P-402 The association between embryo morphology and first trimester miscarriage after single blastocyst transfer

Abstract Study question Can standard morphological assessment of blastocyst quality accurately predict first trimester miscarriage? Summary answer Decreasing trophectoderm and inner cell mass grade equally predicted first trimester miscarriage independently. After adjusting for confounders, poor embryo quality was not associated with miscarriage. What is known already Embryo quality determined by morphological assessment is a well-established predictor of successful implantation and live birth with in vitro fertilization treatment. Chromosomal abnormalities account for over half of first trimester miscarriages, and links between ploidy status and embryo morphology have been demonstrated. However, the association between blastocyst morphology and first trimester miscarriage is still poorly understood with consensus opinion yet to be established. Study design, size, duration This single centre retrospective cohort study included 2020 fresh and frozen single embryo transfers between October 2010 and October 2020. Blastocyst degree of expansion, inner cell mass (ICM) grade, and trophectoderm (TE) grade were compared for 354 pregnancies ending in first trimester miscarriage and 1666 pregnancies that surpassed 12 weeks of gestation. The association between blastocyst morphology and miscarriage was examined by logistic regression analysis. Participants/materials, setting, methods All single blastocyst transfers over a 10-year period resulting in first trimester miscarriage or pregnancy beyond 12 weeks of gestation were included in our analysis. Cycles involving donor oocytes, preimplantation genetic testing, resulting in biochemical pregnancy, or ectopic pregnancy were excluded. Differences between groups were analysed with chi-square and logistic regression analysis. Odds ratios (aOR) for miscarriage versus ongoing pregnancy were adjusted for maternal age, cycle type, blastocyst expansion, ICM grade, and TE grade. Main results and the role of chance Out of 2020 single embryo transfer cycles, a total of 354 resulted in first trimester miscarriage (17.5%). Independently, miscarriage rates increased with decreasing ICM grade (A to C; 14.6%, 18.9%, and 26.5%, p = 0.003) and TE grade (A to C; 14.6%, 17.7%, and 26.6%, p = 0.004). Univariate logistic regression showed higher risks of miscarriage with ICM grade C compared to ICM grade A (OR 2.241, 95%CI 1.292-3.886, p = 0.004), TE grade C compared to TE grade A (OR 2.116, 95%CI 1.360 – 3.292, p = 0.001), and expansion grades of 1 and 2 compared to expansion of 5 and 6 (OR 2.514, 95%CI 1.477 – 4.278, p = 0.001). After multivariable logistic regression adjusting for maternal age at embryo transfer, cycle type, and all morphological parameters (degree of expansion, ICM, and TE), only expansion grade of 1 and 2 showed a statistically significant association with first trimester miscarriage. Limitations, reasons for caution The main limitation of this study is the retrospective design of the analysis, and subjective nature of embryo morphological assessment. There may also be residual confounding by unknown or unmeasured confounders such as paternal age or maternal BMI. Wider implications of the findings Embryo selection for transfer should continue to be guided by standard morphological assessment. Decreasing grade of ICM and TE are both positively associated with an increased miscarriage risk, while poorly expanded blastocysts are most predictive of first trimester miscarriage. Patients undergoing embryo transfer should be adequately counselled about these risks. Trial registration number Not applicable

P-126 Investigation of the deterministic value of presence of visible spindle on fertilization and blastocytes utilization potential in frozen/thawed oocyte cycle

Abstract Study question Does presence or absence of birefringent spindle after warming of the oocytes has deterministic value on fertilization and early embryonic development potentiaL? Summary answer The warmed oocytes with birefringent spindle seem to have a higher potential to fertilize and become good quality blastocytes. What is known already To date, characteristics of the meiotic spindles in human oocytes were studied by several authors by using a non-invasive method (PolScope) and shown that they are associated with fertilization, embryo quality, pregnancy, and live birth rates. Also, it has been known that meiotic spindle structures are very susceptible to cryodamage and can be disassembled and re-assembled depending on the change in temperature. Thus, studying spindle characteristics of the vitrified-warmed oocytes is important and can provide information about the full recovery of the oocytes, fertilization, embryo development, and pregnancy, which the data is limited in the literature. Study design, size, duration A retrospective study consisting 40 egg donation cycles by using vitrified-warmed oocytes between December 2017 and December 2019 at British Cyprus IVF Hospital. Participants/materials, setting, methods Spindle morphologies of vitrified-warmed oocytes were analyzed by PolScope (RI) combined with an image analysis system after approximately 1.5 hours post-warming. The data is divided into two according to the presence or absence of visible nucleus and correlation with embryonic development analyzed accordingly. To make a comparison in groups a new numerical scoring system for embryo quality on days 5 and 6 was created where embryos scored depending on the stage of expansion, Main results and the role of chance In total, 587 out of 648 vitrified/warmed oocytes survived (90.6%) and 447 of them were fertilized (75.0%). Among the survived oocytes, 503 (85.5%) oocytes were containing detectable spindle (Group I) while spindles were missing in 84 oocytes (Group II). The results showed that the fertilization rate (78.1% vs. 64.3%, p &amp;lt; 0.01), the proportion of good PN morphology (Z Score: Z1 and Z2 over other parameters: 50.4% vs 35.2%, p = 0.036), and viable embryo count (40.6% vs 15.1%, p &amp;lt; 0.01) which is defined as embryos that good enough to transfer or freezing, were higher in group I. Similarly, the degree of expansion on day 5/6 (p = 0.013, p = 0.015 respectively) and the quality of the cells in ICM and TE (p &amp;lt; 0.01) were found higher in group I. We further investigated the differences in embryo quality between groups by converting the embryo grades to numerical value starting from arrested (Score=0) to 6AA (Score=22) and found that embryo scores on day 5 (p = 0.01) and day 6 (p = 0.013) were higher in group I. Limitations, reasons for caution The main limitation of this study is the lack of data regarding the spindle status of the frozen oocytes before vitrification where some of the oocytes might not have visible spindle due to incomplete maturation rather than cryodamage. Wider implications of the findings The present data showed that the presence of birefringent meiotic spindles in warmed oocytes is a very important sign for a full recovery and early embryonic development potential, which can be useful for egg banks and IVF clinics. Trial registration number not applicable

O-008 Low grade blastocysts result in healthy live births and should not be discarded

Abstract Study question Does transfer of low grade blastocysts results in acceptable live birth rates the birth of healthy babies? Summary answer While BC/CB/CC blastocysts have a reduced chance of live birth compared with AA/AB/BA/BB blastocysts, the absolute chances are still reasonable. What is known already Transfer of poorer quality embryos and blastocysts result in lower live birth rates, though to what extent is unclear, nor if there is an absolute threshold below which live births are very rare or even do not occur. Further, the developmental competence of the inner cell mass (ICM) or trophectoderm (TE) could at least theoretically impact the pregnancy and/or the health of the baby. Many clinics do not transfer or freeze poor quality embryos and blastocysts, and prefer to submit the patient to a further stimulation cycle. Study design, size, duration We performed a retrospective analysis of 10,978 couples undergoing singleton blastocyst transfers between 2009 and March 2020. We included all single blastocyst transfers for which there was complete data on blastocyst quality, singleton or twin births, birthweight and gestation at delivery, irrespective of blastocyst grading, female age, cause of infertility, ovarian response or endometrial thickness. We recorded live birth rates, birth weight and gestational age. Participants/materials, setting, methods Data from 14 clinics in 3 countries, 8 from China, 5 from New Zealand, and 1 from Australia were included in the final dataset. We compared the impact of blastocyst grading using multiple logistic regression. Blastocyst grading was based on the Gardner classification, in which the first letter denotes the grade of the inner cell mass (A is best), and the second letter the grade of the trophectoderm. Main results and the role of chance Overall, 10,978 single blastocyst cycles resulted in 4,261 live births (38.8%) (4195 singletons and 132 twins). Live birth rates were 47% after transfer of AA blastocysts (n = 2306); 42% after AB/BA (n = 2088); 33% after BC (n = 1973); 25% after CB (n = 715) and 14% after CC (n = 117). There were too few AC (n = 27) or CA (n = 12) blastocysts to include in the analysis. The odds of live birth for BC/CB/CC blastocysts compared with AA/AB/BA blastocysts, vary between 0.8 and 0.9. The live birth rate appears to be more dependent on ICM quality (C grade, n = 844, 23.2%) rather than TE quality (C grade, n = 2117, 32.1%), with the odds of live birth 0.43 and 0.57 respectively compared to A grade ICM or TE. The average birth weight (singleton only) was 3336.9+/-570.3 g (range 3323 to 3386 g), and the average gestation at delivery (singleton only) was 38+6+/-2.0 weeks (range 38+2 to 39+1). There was no significant difference for birth weight or gestational age at delivery between blastocysts of different grades. Limitations, reasons for caution This was a retrospective study. Grading was based on inner cell mass and trophectoderm and not on degree of expansion, or on day of transfer. It is likely that higher quality blastocysts were transferred first, in a fresh cycle, and poorer quality blastocysts frozen for later transfer. Wider implications of the findings The most important finding is that reasonable live birth rates are obtained in CC-blastocysts. We therefore advocate that CC-blastocysts should be replaced or frozen for later transfer. It is reassuring that there was no impact of blastocyst quality on birth weights or gestational age at the time of delivery. Trial registration number Not applicable

P-193 Using blastocyst re-expansion rate in the decision-making when to warm a new blastocyst for optimal single vitrified-warmed blastocyst transfer

Abstract Study question Can post-warmed blastocyst re-expansion rate be used to identify embryos with low likelihood of live birth (LB) in single vitrified blastocyst transfer (SVBT)? Summary answer A statistical model using blastocyst re-expansion rate and Gardner score can be used to identify blastocysts that do not result in live birth. What is known already The ability to identify the most viable embryo with greatest chance of implantation and LB is crucial. As embryo development is a dynamic process, research has recently focused on finding the most predictive morphokinetic parameters to incorporate in the assessment of which embryos to select for transfer. Time-lapse systems allow continuous monitoring of the embryo while cultured uninterruptedly. Several studies have found that the degree of blastocoele expansion and re-expansion are significant parameters for prediction of LB. Furthermore, re-expansion rate has been demonstrated to correlate with pregnancy outcomes in SVBT. Study design, size, duration This study is a retrospective cohort study including a total of 931 SVBT´s at the Fertility Clinic at Horsens Regional Hospital in a 2-year period from 2019-2020. Prior to vitrification, laser assisted collapsing was performed on all blastocysts with an expansion grade ≤ 4, and grade 5 after individual assessment. Only blastocysts with data on both pre-vitrification Gardner score, LB outcome and at least two hours of post-warmed time-lapse data were included in the analysis. Participants/materials, setting, methods Using a time lapse system, both fresh and post-vitrification embryo developmental parameters were evaluated during culturing in an EmbryoScope (Vitrolife, Denmark). Re-expansion rate was calculated as the change in blastocyst area within the first two hours. Logistic regression models were used to estimate the relation between LB and pre- and post-vitrification variables. Based on model predictions, the diagnostic performance was evaluated at thresholds corresponding to a 1%, 2% and 5% false negative rate (FNR). Main results and the role of chance Of the 931 SVBT´s, a total of 388 resulted in a LB (41.7%). Using the initial blastocyst size and the two-hour re-expansion rate yielded a model with an area under the ROC curve (AUC) of 0.61 (95% bootstrap CI: 0.57-0.65) Adding pre-vitrification Gardner score to the model increased the AUC to 0.62 (95% bootstrap CI: 0.59-0.66). This model was used to calculate the true negative rate (TNR), being the proportion of transferred blastocysts that would not result in LB at each threshold. At a FNR threshold of 2%, the model predicts that out of 50 discarded blastocysts, 7 would have resulted in a LB and 43 would not have resulted in LB. In summary, the ratio of erroneously discarded embryos vs. correctly discarded embryos would be approximately 1:6 using a 2% FNR. Limitations, reasons for caution The statistical model was developed and tested on the same dataset with a risk of overfitting. Any potential clinical application of the model requires testing and validation on an independent dataset. Furthermore, clinical procedures and in particular laser collapse may bias the results. Wider implications of the findings Being able to identify blastocysts with a low likelihood of a LB allows for the possibility to thaw a new blastocyst. In a clinical setting, this could lead to a reduced time to pregnancy and LB in women who have multiple vitrified blastocysts. Trial registration number 1-16-02-583-20