Degree Of Expansion Research Articles

Strain Measurement on a PBX during Temperature Cycling Using Fibre Bragg Gauges

AbstractThe anisotropic and irreversible expansion properties of polymer‐bonded explosives (PBX) can significantly influence the utility and reliability of associated equipment. The physical state of PBX under temperature cycling affects the strain distribution across the surface of cylindrical specimens. This strain is indicative of the irreversible growth and anisotropic expansion of the specimens. In this study, fiber Bragg grating sensors are employed to monitor the strain of PBX throughout the temperature cycling process, and our focus was on analyzing the changes in anisotropy and strain distribution during the cycle. The relationships between strain, temperature, material properties, and differences among various materials are examined. Experimental results indicate that the strain along the height and radial directions of the PBX specimens displayed a monotonic gradient distribution, increasing progressively in areas of higher density. TATB‐based PBX exhibited anisotropic expansion throughout the temperature cycling, with the degree of anisotropy increasing during heating and decreasing upon cooling. Conversely, HMX‐based PBX showed greater expansion in the height direction during both the heating and cooling phases, but it did not display noticeable anisotropy following the temperature cycling. At the highest temperature‐holding stage (100°C), the HMX‐based PBX was isotropic. The extent of strain in PBX was correlated with the thermal expansion coefficient of the crystal, although the final degree of expansion was not dependent on the initial range of strain. The ratchet growth of TATB‐based PBX was approximately 31 μϵ greater than that of HMX‐based PBX.

IOP Reduction in Nonhuman Primates by Microneedle Injection of Drug-Free Hydrogel to Expand the Suprachoroidal Space.

Expansion of the suprachoroidal space (SCS) by a hydrogel injection has been shown to reduce intraocular pressure (IOP) in rabbits as a potential treatment for ocular hypertension in glaucoma. Here, we evaluate the safety and efficacy of this approach in hypertensive and normotensive eyes in nonhuman primates. A microneedle was used to inject a hyaluronic acid-based hydrogel or saline solution (control) into the SCS of cynomolgus monkey eyes that were either normotensive (n = 7 experimental; n = 2 control eyes) or had induced ocular hypertension (n = 6 experimental; n = 3 control eyes). IOP and the degree of SCS expansion were monitored over time by tonometry and ultrasound biomicroscopy, respectively. Safety was evaluated through slit lamp, fundus, and histology examinations. In hypertensive eyes, SCS injection with hydrogel initially reduced IOP by 47.5 ± 16.7%, and IOP returned to baseline in 38 days. In normotensive eyes, hydrogel injection initially reduced IOP by 38.8 ± 8.1% and IOP gradually returned to baseline also in 39 days. Sham injections resulted in mild IOP reduction in hypertensive eyes and normotensive eyes. The hydrogel injections were well tolerated by clinical assessments. IOP was reduced in nonhuman primates for over one month by sustained SCS expansion. This procedure was safe and simple to perform. These data confirm the translational potential of this treatment method. Further optimization of the hydrogel may provide longer durations of IOP reduction. A microneedle injection of hydrogel into the suprachoroidal space may provide a non-surgical, non-pharmacologic treatment for ocular hypertension in glaucoma patients.

Compensating for Concrete Shrinkage with High-Calcium Fly Ash

Shrinkage of concrete during hardening is a serious problem in attempts to maintain the integrity of concrete structures. One of the methods of combating shrinkage is compensating for it using an expansive agent. The purpose of this work is to develop and study an expanding agent to concrete, including high-calcium fly ash and calcium nitrate as an expansion activator. The content of Ca(NO3)2 can be used to regulate the degree of expansion of the additive itself during hydration and, accordingly, to control shrinkage, thus obtaining shrinkage-free or expanding concrete. Shrinkage–expansion deformations of concrete can also be regulated by the amount of expanding additive replacing part of the cement. With the Ca(NO3)2 content of fly ash being 10% or more, concrete experiences expansion in the initial stages of hardening. The transition of deformation through 0 to the shrinkage region occurs depending on the composition and content of the additive after 8–15 days of hardening. It has been established that replacing cement with pure fly ash with a curing period of 90 days or more has virtually no effect on the strength of concrete, either in bending or in compression. The use of an expanding additive containing 5–15% Ca(NO3)2 reduces the strength of concrete by an average of 9%, despite the fact that calcium nitrate is a hardening accelerator.

Clinical validation of the early embryo viability assessment system: Analysis for the blastocyst morphology and pregnancy outcomes

Objective: To determine the relationship between the early embryo viability assessment (EEVA) and blastocyst morphological parameters and pregnancy outcomes. Methods: This retrospective cohort study was conducted on 291 intracytoplasmic sperm injection cycles including 2 522 embryos with indications of prolonging embryo culture to the blastocyst stage in the Genea embryo review incubator, and 511 single vitrified- warmed blastocyst transfer cycles from January 2020 to June 2023. The EEVA system produced an EEVA score from E1 (best) to E5 (worse) for the potential of blastocyst formation. Blastocyst morphology was evaluated. The association between the EEVA score and each type of blastocyst morphology, implantation rate, clinical pregnancy, and ongoing pregnancy were assessed using generalized estimating equations. Results: The inner cell mass A (ICM A), trophectoderm A (TE A), blastocoele expansion degree of 3, 4, 5, 6, 7 rates were higher with lower the EEVA score. The adjusted odd ratio (aOR) (E5 vs E1) was 0.3 for ICM A, 0.174 for TE A and 0.210 for BL3, 4, 5, 6, 7 (all P<0.001), suggesting a significant association between lower EEVA scores and improved embryo quality. The implantation, clinical pregnancy, and ongoing pregnancy rate were also higher with lower the EEVA score. The aOR of E5 vs E1 was 0.245 for implantation, 0.185 for clinical pregnancy and 0.200 for ongoing pregnancy rate (P<0.001). Conclusions: There were associations between blastocyst morphology, pregnancy outcome and EEVA scores. The good blastocyst morphology and pregnancy outcomes are higher with lower the EEVA score.

Global Distribution Prediction of Cyrtotrachelus buqueti Guer (Coleoptera: Curculionidae) Insights from the Optimised MaxEnt Model.

Cyrtotrachelus buqueti Guer is a major pest affecting bamboo forests economically, causing significant damage to bamboo forests in Sichuan Province, China. To understand how C. buqueti responds to future climate conditions, an optimized Maximum Entropy Model (Maxent) was used to simulate the potential global distribution patterns of C. buqueti under current climate conditions and three different future climate scenarios and to analyze the dominant factors influencing its distribution. The results indicate that Bio18 (precipitation of the warmest quarter), Bio04 (temperature seasonality), Bio06 (minimum temperature of the coldest month), and Bio02 (mean diurnal temperature range) are the main environmental factors affecting the distribution of this species. The global area of high-suitability habitats for C. buqueti is 9.00 × 104 km2, primarily distributed in China. Under three different future climate scenarios, there are varying degrees of expansion in both the total suitable habitat and the medium-suitability areas for C. buqueti. Under the SSP5-8.5 scenario, the medium-suitability area of the species increases the most, reaching 9.83 × 104 km2. Additionally, these findings can serve as a reference for developing and implementing control strategies, assisting relevant authorities in more effectively managing and controlling this pest, and mitigating its potential threats to bamboo forest ecosystems and economies.

Elucidating the hemodynamic impact of residual stenosis post-carotid artery stenting: A numerical study.

Residual stenosis (RS) and hemodynamics demonstrate a significant correlation with postoperative in-stent restenosis/thrombosis following carotid artery stenting (CAS). This study endeavors to elucidate the potential associations between RS and adverse postoperative hemodynamic factors. This study utilized 46 patient-specific carotid artery models post-stenting, which were categorized into two groups based on the presence of RS: the normal group (N, n=23) and the RS group (RS, n=23). A comparative analysis was conducted to evaluate the discrepancies in geometry and adverse hemodynamic parameters, alongside investigating the potential correlation between hemodynamic and geometric parameters. The results reveal that a higher reflux flow volume is discernible in the RS group during low-velocity phases of the cardiac cycle, concomitant with an augmented extent of areas exposed to oscillatory shear stress and extended particle residence time. Moreover, the adverse hemodynamic parameters exhibit a positive correlation with the degree of stent expansion, stent length in the common carotid artery (CCA), and the distal slope of the RS. The distal slope and tortuosity of RS significantly influence the development of adverse hemodynamic conditions post-stenting, exacerbating the hemodynamic environment near the stenosis. Interestingly, while an extended stent length in the internal carotid artery (ICA) region improves hemodynamics by reducing flow disturbance, a longer stent in the CCA significantly worsens these conditions. Hence, it is prudent to analyze the characteristics of the local lesion regions to optimize the strategy for stent implantation.

Three-dimensional analysis of decompression efficacy and influencing factors in the maxillofacial cystic lesions: a retrospective study.

To evaluate the effectiveness of decompression and various parameters that may affect volume change in cystic lesions. Patients and. This retrospective study included patients who visited the Department of Oral and Maxillofacial Surgery at Ewha Womans University Medical Center between 2012 and 2022 for decompression of cystic lesions of the jaw. To measure volume changes, pre- and post-decompression cone-beam computed tomography was performed and reconstructed in three dimensions using Mimics 25.0 software (Materialise NV). A comparative analysis was performed based on sex, age, initial cyst volume, location, degree of cortical layer expansion, and pathologic diagnosis using the Mann-Whitney U and Kruskal-Wallis tests. In all 20 cases, the duration of decompression was 7.84±3.35 months, and all patients successfully completed the decompression period without any complications. Significant differences were observed in the reduction rate and shrinkage speed based on the degree of cortical layer expansion. However, only the shrinkage speed (not the reduction rate) showed a significant difference with respect to the initial cyst volume. Significant differences were not observed based on sex, age, location, or pathologic diagnosis. Although the present study involved a small number of cases, the effectiveness of decompression was confirmed. In particular, 3D analysis overcame the shortcomings of previous studies of decompression and allowed earlier resection. Further studies with more patients are required to provide a rationale for these results and identify factors that influence decompression.

Effect of raw material fineness on the properties of inorganic foam materials from solid waste

Solid waste inorganic lightweight materials not only compensate for the flammability of organic materials but also have a lower carbon footprint. They are environmentally safe and cost-effective compared with cement-based foaming materials, and they have good development prospects. This study aimed to improve the chemical foaming reaction kinetics by reducing the particle size of aluminum powder and alkaline solid waste, thereby increasing the expansion degree of solid waste slurry, to further reduce the absolute dry density of inorganic lightweight materials for solid waste and optimize their performance. The influence of the particle size of raw material on the absolute dry density, water absorption, and compressive strength of lightweight materials was investigated. The influence of the particle size of raw material on the macroscopic pore structure of foamed materials was analyzed through binarization of cross-sectional images of specimens. Furthermore, the hydration products and microstructure of materials were characterized using XRD, FTIR, TG-DTG, and SEM to provide a theoretical basis for related research. The experimental results showed that the smaller the particle size of the raw material, the easier it was to carbonize and the lower the flowability of the corresponding cementitious material slurry. Reducing the particle size of raw materials and aluminum powder increased the degree of slurry expansion, thereby reducing the absolute dry density of foaming materials. In addition, reducing the particle size of raw materials and using carbide slag wastewater instead of tap water increased the degree of foaming reaction and hydration reaction, which helped C-(A)-S-H gel formation and promoted the development of sample strength. Finally, the absolute dry density of inorganic lightweight materials was reduced to 0.35 g/cm3 at the minimum, and the corresponding 28-day compressive strength was 0.28 MPa, which met the requirements of the JG/T 266–2011 “foam concrete” specification.

Evaluation of Geotechnical Properties of Soil at Selected Sites in Al-Nasiriya City

Soil index properties are used to calculate and determine the geotechnical properties of soils and then determine soil suitability for the construction of engineering projects. Most of the geotechnical properties of soil affect each other directly or indirectly, and these properties can be utilized as indicators to calculate other properties. In the present study, some soil index properties were used to identify the geotechnical properties of soil. According to the unified classification system for soil, most soils were classified as low and high plasticity hilt. In addition, the soils showed a medium to a high degree of expansion according to the values of the Atterberg limit and were generally considered inactive clay soil. Based on the Standard Penetration Test values, consistency index, and compression index, the soil was stiff to extremely stiff and had high to extremely high compressibility. Finally, the results showed the need for soil for some engineering works, such as stabilization and modification, before the construction of engineering projects.

Effect of different chain-length fatty acids on the retrogradation properties of rice starch

In order to delay the retrogradation of rice starch, the effects of three different chain length fatty acids (lauric acid, myristic acid and palmitic acid) on rice starch were studied. The fatty acids with longer carbon chains had strong steric hindrance and hydrophobicity, which formed a more compact structure in the helical cavity of amylose, and significantly reduced degree of expansion, migration of water, short-range ordered structure, number of double helical structures and crystallinity. These structural changes endowed the rice starch-long chain fatty acid complexes with better gel viscosity, liquid fluidity and thermal stability than in the rice starch-short chain fatty acid complexes. The results showed that fatty acids with longer chain length inhibited the retrogradation of rice starch, most obviously when 5% palmitic acid was added. This study provides an important reference for the processing of rice starch-based foods.

Determination of Uranium Central-Field Covalency with 3d4f Resonant Inelastic X-ray Scattering.

Understanding the nature of metal-ligand bonding is a major challenge in actinide chemistry. We present a new experimental strategy for addressing this challenge using actinide 3d4f resonant inelastic X-ray scattering (RIXS). Through a systematic study of uranium(IV) halide complexes, [UX6]2-, where X = F, Cl, or Br, we identify RIXS spectral satellites with relative energies and intensities that relate to the extent of uranium-ligand bond covalency. By analyzing the spectra in combination with ligand field density functional theory we find that the sensitivity of the satellites to the nature of metal-ligand bonding is due to the reduction of 5f interelectron repulsion and 4f-5f spin-exchange, caused by metal-ligand orbital mixing and the degree of 5f radial expansion, known as central-field covalency. Thus, this study furthers electronic structure quantification that can be obtained from 3d4f RIXS, demonstrating it as a technique for estimating actinide-ligand covalency.

Software Key Node Recognition Algorithm for Defect Detection based on Node Expansion Degree and Improved K-shell Position

Software Key Node Recognition Algorithm for Defect Detection based on Node Expansion Degree and Improved K-shell Position

An extended cellular automation model for bicycles with group and retrograde behaviors at signalized intersections

The rise of shared bicycles has increased the demand for group riding, integrating bicycles into social groups. Additionally, retrograde riding, where cyclists travel against the designated direction, is a common behavior observed in bicycle flows. The interaction and self-organization phenomenon of group and retrograde behaviors are complex, significantly impacting traffic efficiency. This paper develops a two-dimensional Extended Moore Neighborhood and constructs state-updating rules for regular riding, group riding and retrograde riding. Each rule comprises a psychological decision layer and a physical execution layer, forming a cellular automaton model for group and retrograde bicycles. Field experiments are conducted to calibrate the model parameters and verify the behavioral characteristics. Finally, we execute numerical simulations at a signalized intersection to explore the coupling effects of group and retrograde behaviors on self-organization within the bicycle flow and the traffic capacity. The results indicate that group behavior increases queue length while reducing start wave speed and expansion degree. Retrograde behavior intensifies the negative effects on bicycle flow. These findings provide insights for managing both forward and retrograde bicycle flows.

A numerical study on the influence of multiple nozzles on the infrared radiation signatures of liquid rocket exhaust plumes

A numerical study was conducted to examine the relationship between the infrared radiation characteristics of liquid rocket engine exhaust plumes under the same thrust conditions and the number and expansion degree of nozzles. This study used the Reynolds-averaged computational fluid dynamics method to simulate the flow field of multiple nozzles. A single-line group combined with the G-C approximation was used to calculate the molecular spectral properties, and a three-dimensional radiation transfer calculation model was established based on the line-of-sight method. The infrared radiation characteristics of the exhaust plume were calculated for single, double, three, and four nozzles. The radiation intensity of two typical bands, 2.7 μm and 4.3 μm, was studied, including spectrum, intensity, and radiation intensity distribution. The results show that the integrated infrared radiation intensity of the double-nozzle plume is 51.36 % lower than the average of the other three nozzle configurations under the over-highly under-expansion state. The radiation difference of the double nozzle reaches up to 38.3 % at different detection angles, whereas the differences between the three and four nozzles are below 10.5 % and 6.1 %, respectively, indicating that the radiation difference at each detection angle gradually decreases with the increase in the number of nozzles.

Recovery of Learning and Memory Deficits Despite Persistent Pyknosis of the Hippocampal Pyramidal Neurons of Adult Hydrocephalic Mice.

The hippocampal alterations resulting from hydrocephalus are associated with various cognitive dysfunctions. Reduced learning and memory are early functional deficits that recover with time in experimental hydrocephalus. This study investigated the recovery processes of learning and memory loss in relation to the morphology of hippocampal pyramidal neurons and the degree of expansion of the ventricles. Hydrocephalus was induced in adult mice by intracisternal injection of sterile kaolin while controls received sham operation. Neurobehavioral tests for memory and learning were conducted, after which the animals were sacrificed in batches: 7 (acute) and 28 (subacute) days postinduction. After sacrifice, mice were categorized into mild and moderate hydrocephalus, and their fixed brain samples were processed for hematoxylin, eosin, and Nissl stains. In moderate acute hydrocephalus, the indices of learning and memory were reduced escape latency (67.20 ± 12.83 s), number of platform crossing (4.000 ± 1.658), duration in platform quadrant (4.000 ± 1.658), and percent of total investigation (44.857% ± 3.981%) but not in the subacute stage. Pyknotic indices (PI) were significantly higher in the cornu ammonis (CA)1 and 3 regions in all hydrocephalic groups than in controls. However, within groups, PI was significantly higher only in the CA1 of moderate acute (28.149% ± 1.875%) compared to moderate subacute hydrocephalic group (12.903% ± 3.23%). Hydrocephalus caused cellular injury to the hippocampus associated with spatial learning and memory deficits. However, these functional deficits were partially reversed in moderate subacute hydrocephalus despite the persistence of the structural alterations in the CA1 and CA3 subregions.

Exploring the Spatiotemporal Evolution Patterns and Determinants of Construction Land in Mianning County on the Eastern Edge of the Qinghai–Tibet Plateau

Studying the spatiotemporal evolution and driving forces behind construction land amidst the intricate ecological and geological setting on the eastern edge of the Qinghai–Tibet Plateau offers invaluable insights for local sustainable development in a landscape transition zone and ecologically fragile area. Using construction land data from four phases, spanning 1990 to 2020, in Mianning County, this study employs methodologies like the Landscape Expansion Index (LEI) and land use transfer matrix to delineate the spatiotemporal evolution characteristics of construction land. A comprehensive set of 12 influencing factors across five categories—geomorphology, geological activity, climate, river and vegetation environment, and social economy—were examined. The Geographically Weighted Regression (GWR) model was then employed to decipher the spatial distribution pattern of construction land in 1990 and 2020, shedding light on the driving mechanisms behind its changes over the three decades. The research reveals distinct patterns of construction land distribution and evolution in Mianning County, shaped by the ecological and geological landscape. Notably, the Anning River wide valley exhibits a concentrated and contiguous development mode, while the Yalong River deep valley showcases a decentralized development pattern, and the Dadu River basin manifests an aggregation development mode centered around high mountain lakes. Over the study period, all three river basins witnessed varying degrees of construction land expansion, transitioning from quantitative expansion to qualitative enhancement. Edge expansion predominantly characterizes the expansion mode, complemented by leapfrog and infilling modes, accompanied by conversions from cropland and forest land to construction land. An analysis of the spatial pattern and drivers of construction land change highlights human-induced factors dominating the Anning River Basin, contrasting with natural factors prevailing in the Yalong River Basin and the Dadu River Basin. Future efforts should prioritize climate change considerations and environmental capacity, aiming for an ecologically resilient spatial pattern of construction land.

P-212 Balancing success and safety in assisted reproductive technologies cycles: the outcomes of transferring poor-quality blastocyst or day 5 slow-growing embryos with good-quality blastocyst

Abstract Study question Does transferring two mixed-quality embryos improve the live birth rate (LBR) without increasing the multiple gestation rate compared to the single good-quality blastocyst (GQB) transfers? Summary answer The transfers of single GQB and two mixed-quality embryos show similar LBRs, however, the multiple gestation rate was significantly higher in double embryo transfer groups. What is known already Due to higher LBR after blastocyst transfer, the single embryo transfer (SET) strategy has gained popularity worldwide. Despite that double-embryos transfers (DET) demonstrate higher LBR than SET, multiple gestation rates (MGRs) are higher in DET. To reduce MGR but still accomplish high LBR, DETs could be performed using embryos of mixed-quality. It has been suggested that the transfer of GQB with poor-quality blastocyst (PQB) could increase LBR without increasing MGR. Alternatively, when the embryo transfer is scheduled in a fresh cycle, the DET could be performed with GQB and day 5 slow-growing embryo (SGE) – early blastocyst or morula. Study design, size, duration This study included assisted reproductive technologies (ART) cycles with fresh embryo transfer on day 5, between 2015 and 2021, for patients under 34 years. Selected ART cycles were assigned into five groups: SET with GQB (SET-GQB, n = 754); DET with two GQBs (DET-GQB, n = 306); DET with one GQB and one PQB (DET-GP, n = 75); DET with one GQB and one day 5 SGE (DET-GS, n = 386), DET with two day 5 SGE (DET-SGE, n = 209). Participants/materials, setting, methods According to Gardner and Schoolcraft’s grading system, blastocyst morphological assessment was performed on day 5. Blastocysts graded as AA, AB, BA, and BB with a degree of expansion ≥3 were classified as GQBs, whereas blastocysts graded ВС, СВ, СС with a degree of expansion ≥3 were classified as PQBs. Day 5 morulas and blastocysts with degree of expansion 1 were classified as slow-growing embryos. The cycles with donor gametes, preimplantation genetic testing were excluded. Main results and the role of chance The LBR was significantly higher in DET-GQB than in SET-GQB [53,59% (164/306) vs 40,58% (306/754); P < 0,001]. There were no significant differences in implantation rate (IR) and miscarriage rate (MR) between SET-GQB and DET-GQB [47,88% (361/754) vs. 44,12% (270/612) P = 0,165], [12,19% (44/361) vs. 10,00% (27/270) P = 0,389]. However, the MGR was significantly higher in DET-GQB compared to SET-GQB [36,59% (60/164) vs 1,31% (4/306) P < 0,001]. When SET-GQB was compared with DET-GS, DET-GP there were no significant differences in LBR: [40,58% (306/754) vs. 39,64% (153/386) P = 0,757; vs. 41,33% (31/75) P = 0,899]. The IR was significantly higher in SET-GQB than in DET-GS and DET-GP [47,88% (361/754) vs. 30,70% (237/772) P < 0,001; vs. 30,00% (45/150) P < 0,001]. There were no significant differences in MR between SET-GQB and DET-GS, DET-GP [12,19% (44/361) vs. 17,30% (41/237) P = 0,079; vs. 11,11% (5/45) P = 0,834]. However, the MGR was significantly lower in SET-GQB compared to DET-GS, DET-GP [1,31% (4/306) vs. 18,95% (29/153) P < 0,001; vs. 22,58% (7/31) P < 0,001]. The IR and LBR were significantly higher in SET-GQB compared to DET-SGE [47,88% (361/754) vs 16,99% (71/418) P < 0,001], [40,58% (306/754)vs 19,14% (40/209) P < 0,001]. The MR and MGR were significantly lower in SET-GQB than in DET-SGE [12,19% (44/361) vs 32,39% (23/71) P < 0,001], [1,31% (4/306) vs 15,00% (6/40) P < 0,001]. Limitations, reasons for caution The study is limited due to the uneven distribution and a low number of participants in group DET-GP. Blastocyst morphological assessment remains subjected to a human factor. It was impossible to form a group where two PQBs were transferred, as there were only a few cases of such transfers. Wider implications of the findings Transferring an additional poor-quality embryo (poor-quality blastocyst or day 5 slow-growing embryo) does not increase the live birth rates. However, it significantly raises the multiple gestation rate. Despite the low live birth rate when two day 5 slow-growing embryos are transferred, the multiple gestation rate significantly increases, compared to SET. Trial registration number Not applicable

P-146 The importance of cytoplasmic strings between inner cell mass and trophectoderm after blastulation on embryonic development and pregnancy outcome

Abstract Study question Whether the cytoplasmic strings between inner cell mass and trophectoderm during blastocyst expansion have a significant impact on embryo development and pregnancy outcomes? Summary answer The presence of cytoplasmic strings is related to morphological quality, but it has no impact on embryo ploidy or clinical outcome after euploid embryo transfer. What is known already Cytoplasmic strings are a dynamic cellular structure, and their width and length vary with the degree of embryonic expansion. The presence of cytoplasmic strings is considered a characteristic of embryos with poor vitality. In recent years, researchers have found the presence of cytoplasmic strings may indicate a higher embryonic developmental potential. However, the specific function of cytoplasmic strings remains unclear, and their impact on embryonic development is still controversial. Study design, size, duration A retrospective cohort analysis was conducted on clinical data of 530 patients who underwent single blastocyst transfer after pre-implantation genetic testing for aneuploidy (PGT-A) in our center from June 2019 to December 2021. Two embryologists annotated the presence of cytoplasmic strings, the morphological quality of blastocyst. Participants/materials, setting, methods A total of 2132 biopsied blastocysts were obtained from the 530 patients, with 534 blastocysts having cytoplasmic strings (+) and 1598 blastocysts having cytoplasmic strings (−). The quality and ploidy differences between the two groups were compared. After PGT-A, single euploid blastocysts were transferred, and the difference in pregnancy outcomes between cytoplasmic strings (+) (n = 115) and cytoplasmic strings (−) (n = 415) cycles was compared. Main results and the role of chance There was no significant difference in the euploidy rate between the two groups (44.6% vs. 45.3%). As the morphological quality of the embryos decreased, the rate of cytoplasmic strings (+) significantly decreased (Good-quality vs. Average-quality: 30.19% vs. 24.62%, P = 0.008; Average-quality vs. Low-quality: 24.62 vs. 12.63, P = 0.000). After adjusting for patient age, anti-Müllerian hormone, and gonadotropin dose, multivariate regression analysis showed that cytoplasmic strings were associated with embryo quality, but not with embryo ploidy. There were no significant differences in implantation rate (72.17% vs. 66.02%, P = 0.213), miscarriage rate (10.43% vs. 8.43%, P = 0.504), and live birth rate (61.74% vs. 57.59%, P = 0.424) between blastocysts with cytoplasmic strings (+) and without cytoplasmic strings (−). Limitations, reasons for caution Larger datasets are required to confirm putative associations between cytoplasmic strings and blastocyst ploidy, and the pregnancy outcome. Wider implications of the findings The presence of cytoplasmic strings is related to the embryological quality of the blastocyst, but it has no impact on embryo ploidy or clinical outcome after euploid embryo transfer. Trial registration number not applicable

P-531 Embryo grading in PGT-A testing: does it really matter?

Abstract Study question Can embryo morphology grading be a good parameter to predict the embryo transfer’s outcome when euploid embryos are used? Summary answer Gardner’s grading is a useful predictor of LBR per euploid embryo transferred. Morphologic grading should be used for the embryo selection among euploid blastocysts. What is known already When preimplantation genetic testing for aneuploidies (PGT-A) is not performed, the selection of the embryo(s) to be transferred is based on embryo morphology. In PGT-A cycle, some studies have minimised the importance of embryo morphology, when euploid embryos are present. However, others still consider it as good predictor. Understanding the role of morphology in biopsied euploid embryos may help in optimizing frozen embryo transfer cycles. Study design, size, duration We retrospectively analysed PGT-A frozen embryo transfers with reported outcome, performed in our clinics between 2018 and 2022. The cycles included were divided into two groups based on Gardner’s grading of euploid embryos transferred: “good” embryos (AA, AB, BA and BB; n = 263) versus “poor” embryos (including AC, CA, BC, CB, and CC; n =112). Participants/materials, setting, methods We included in the study only single euploid embryo transfers, double embryos transfers and mosaic embryo transfers excluded. Body mass index (BMI), oocyte age and outcomes (pregnancy and live birth rates) were compared between the two groups. Data was statistically analysed using MedCalc Software, where P < 0.05 was considered as significant. Main results and the role of chance A total of 375 embryo transfer cycles were included in the study. Maternal ages were not significantly different between groups (good vs poor embryos) (37.5 vs 38.2). Similarly, oocyte age (37.7 vs 38.1, respectively), and BMI (22 vs 22.7, respectively) did not differ between good and poor embryos. On the contrary, clinical pregnancy (56.6% vs 40.1%) and live birth rates (27.7% vs 13.4%) were significantly higher when morphologically good grade embryos were transferred (p < 0.05). In fact, both rates were significantly higher after the transfer of blastocysts that exhibited A-grade or B-grade in inner cell mass and/or trophectoderm, as opposed to the transfers of blastocysts that exhibited a C-grade trophectoderm and/or inner cell mass. Limitations, reasons for caution The findings apply to the participating centres and may not represent worldwide trends. Data was analysed retrospectively, but details of the follow-up on PGT pregnancies and babies born were limited. The degree of blastocyst expansion and the day of biopsy were not taken into consideration in this study. Wider implications of the findings The Gardner embryo quality assessment improves the clinics’ ability to prioritize embryos after PGT. Preferential transfer based on morphologic criteria increases the chances of a positive outcome in terms of live birth rates. Trial registration number not applicable

P-149 A visual interpretability method to unbox ‘black-box’ deep learning image-based classification of embryo properties

Abstract Study question Can we decipher the underlying visual properties that drive image-based AI embryo classification models to assist clinical decisions and biological discovery? Summary answer Our framework interpreted which annotated and non-explicitly-annotated phenotypes impact model predictions and rank their importance. These discoveries were aligned with known blastocyst quality criteria. What is known already Deep learning models have shown great promise for complex pattern recognition when applied to embryo images. The success of these models relies on their ability to perform non-linear optimization of feature extraction during model construction. However, this involves their entanglement of multiple classification-driving image properties, thereby producing ‘black-box’ systems that lack user confidence, trust and interpretability. Therefore, there is an urgent need for an interpretability method that can uncover the semantic image properties that contribute to ‘black box’ embryo image-based AI classification model predictions to assist in blastocyst selection. Study design, size, duration 11,211 time-lapse videos were retrospectively collected from three IVF centers. A deep convolutional neural network is first trained to discriminate high-versus-low quality blastocysts. We then developed DISCOVER, a general-purpose interpretability method designed to discover underlying visual properties driving the classifier. DISCOVER encodes an image to an interpretable lower dimensional representation which is correlated to the classifier and encapsulates a different distinct phenotype in each one of the dimensions. Participants/materials, setting, methods The encoding of embryo images to low dimensional representations enables interpretability globally and locally. Globally, the embryo images are synthetically altered by amplifying subtle properties that affect the classification decision. With our method this can be done one property at a time, therefore separating confounding properties. By evaluating the altered images, embryologists can decipher their meaning. Locally, each one of the discovered properties can be ranked by its importance for a specific embryo instance. Main results and the role of chance Using DISCOVER, we interpreted the classification model driving features. We quantitatively linked the top two classification features as blastocyst size (as proxy to degree of expansion and development) and trophectoderm quality, by embryologists evaluation and annotations. We then asked whether DISCOVER can identify non-explicitly annotated latent features that encode morphologic properties not defined by ASEBIR/Gardner criteria. Expert embryologist interpreted the third top classification feature to be the blastocoel. DISCOVER interpreted high quality embryos as having denser and more granular blastocoelic regions, suggesting that this change in the blastocoel appearance is one of the encoded classification-driving morphologic properties. This visualization indicates that there are additional parameters of the blastocoel beyond its volume expansion associated with its quality. We showed how embryo properties can be weighted differently by the classifier on a per embryo basis, giving clinical insight to which properties influence the classification of a specific instance. These results indicate that DISCOVER enables expert-in-the-loop interpretation of the classification model both globally, discovering the overall main properties driving the classifier, and locally, showing a per instance explanation. Limitations, reasons for caution DISCOVER failed to interpret the inner cell mass (ICM) as a classification-driving feature in its latent representation, though it was explicitly used to label the data for training the classification model. It is possible that other properties collectively contained the discriminative information encoded in the ICM. Wider implications of the findings This deep analysis demonstrates the feasibility of providing interpretability for biomedical image-based classification models for clinical use in the IVF clinic. Trial registration number not applicable