Structural integrity and healing efficiency study of micro-capsule based composite materials via 1H NMR relaxometry

In this work we present a novel approach utilizing nuclear magnetic resonance (NMR) relaxometry to assess the structural stability of microcapsules employed as self-healing agents in advanced aerospace composites both in ambient and harsh environmental conditions. We successfully correlate the amount of the encapsulated self-healing agent with the signal intensity and confirm non-destructively the quantity of the encapsulated self-healing agent mass for the first time in the literature using ¹H NMR spin-spin relaxation techniques on urea-formaldehyde (UF) microcapsules of different diameters containing an epoxy healing agent. The amount of self-healing agent is shown to increase by reducing the capsule diameter; however, the reduced shell mass renders the capsules more fragile and prone to failure. Most notably, via NMR experiments conducted during thermal cycling simulating flight conditions, we demonstrate that the microcapsule integrity under thermal fatigue varies according to their size. Especially we experimentally verify that the microcapsules with the most sensitive shells are the 147 nm and 133 nm diameter microcapsules, which are the most commonly used in self-healing systems. Finally, we were able to retrieve the same results using a portable NMR spectrometer developed in-house for in situ microcapsule testing, thus demonstrating the potential of NMR relaxometry as a powerful non-destructive evaluation tool for the microcapsule production line.

O-065 The effect of double vitrification on embryo reproductive potential and clinical outcome

Study question

Do double-vitrified embryos have impaired implantation potential compared to embryos vitrified once?

Summary answer

Double-vitrified embryos demonstrated significantly lower percentages of positive β-HCG, clinical pregnancy (CPR) and live birth (LBR) compared to embryos vitrified once.

What is known already

Since vitrification became a core player in ART, many clinics adopted a freeze-all strategy, including vitrification of more than one embryo per vitrification device. Nowadays, the guidelines’ suggestion for single embryo transfers often results in a surplus of good quality embryos post warming which are re-vitrified to avoid embryo wastage. Thus, transfers of double-vitrified embryos have been performed worldwide, leading to successful pregnancies. It remains yet to be answered whether embryos after double vitrification exhibit the same reproductive performance as embryos vitrified once. By now, limited studies including various cryopreservation methods show relatively conflicting results.

Study design, size, duration

This retrospective cohort study was conducted in Embryolab Fertility Clinic, Greece. Assisted reproductive cycles included in the study were performed from January 2015 to December 2020. Both PGT cycles and cryopreserved oocyte cycles were excluded. The mean women age was 32.8 years old (±5.9) in the study group and 33 (±5.9) in the control group. There was no variation in the cryopreservation methods used, since all embryos were cryopreserved by the same vitrification protocol.

Participants/materials, setting, methods

For the present study, 233 embryo transfers of 334 double-vitrified embryos (309 blastocysts/25 cleavage embryos) and 172 transfers of 260 embryos vitrified once (246 blastocysts/14 cleavage) were analyzed to explore the impact of double vitrification on positive β-HCG, CPR, LBR and miscarriage rate. Moreover, the performance of embryos that were cultured for at least 24 hours before re-vitrification was compared to embryos warmed and re-vitrified on the same day, for the same parameters mentioned above.

Main results and the role of chance

All embryos survived vitrification (100% survival rate) in both study and control group. An alpha level of .05 was used for all statistical tests. Results showed that positive β-HCG percentage was significantly lower in the double vitrification group (45.1% for double -vitrified embryos -study group-, 57.0% for embryos vitrified once -control group-, p=.02), as well as CPR (28.3% in study group - 42.4% in control group, p=.003) and LBR (26.6% in study group - 40.4% in control group, p=.004). The miscarriage rate did not significantly differ between two groups (35% in study group - 25% in control group, p=.121). Moreover, positive β-HCG percentage was significantly higher in transfers with embryos that were cultured at least 24 hours before re-vitrification (group A: 48.9%), compared to embryos that were warmed and re-vitrified on the same day (group B: 30.6%, p=.02). Interestingly, although CPR (31% in group A, 18.4% in group B, p=.08), LBR (29.4% in group A, 16.3% in group B, p=.06) and miscarriage rate (35.6% in group A, 33% in group B, p=.87) were not significantly different between these groups, there was a tendency for rates to be higher in group A compared to group B.

Limitations, reasons for caution

This is a retrospective study, including transfers of embryos of different stage (day 2 – day 5). However, the control group was matched to the study group, in terms of embryo stage. The number of previous treatments per couple was not included in the study.

Wider implications of the findings

Although double-vitrified embryos can lead to successful pregnancies, our results showed an adverse effect of double vitrification on embryo reproductive potential. To avoid lower pregnancy rates, culture of embryos until day 5 and cryopreservation of one embryo per vitrification device should be considered.

Trial registration number

not applicabe

P-169 Low 5% VS ultra-low 3% O2 concentration on embryo culture: Is there any difference in quality and ploidy?

Study question

Can embryo culture in 3% O2 concentration improve fertilization and blastocyst formation rates, as well as euploidy rate, compared to 5% O2 embryo culture?

Summary answer

Ultra-low oxygen concentration (3%) does not seem to improve fertilization and euploidy rate neither embryo quality and blastocyst formation rate.

What is known already

Low oxygen tension (5%) during embryo culture has found to be beneficial for embryo development, when compared to atmospheric O2 tension (20%). Physiologically, oxygen tension is decreasing from ∼5% in the fallopian tube to ∼2,5% in the uterus and embryos enter the uterus on the post-compaction stage, around Day 4 of their development. Additionally, our previous study demonstrated that euploidy rate was significantly higher in 5% O2 concentration compared to 20%. Thus, the purpose of this study was to evaluate whether culture of embryos to blastocyst stage could benefit from a decrease in O2 concentration, from 5% to 3%.

Study design, size, duration

This retrospective study, included 176 PGT-A cycles, performed at Embryolab fertility clinic from May 2017 to November 2021. Two study groups were formed, in which oxygen tension was the only different parameter of culture conditions; the 5% O2 Group consisted of 114 PGT-A cycles resulting in 832 embryos and the 3% O2 Group with 62 PGT-A cycles including 479 embryos. Euploidy, fertilization and blastocyst formation rates were compared between the two groups.

Participants/materials, setting, methods

In all cycles included in the study, injected oocytes were incubated to either 3% O2 or 5% O2. The CO2 concentration was 6% in both groups. Embryos were cultured to blastocyst stage. In good quality available blastocysts (expansion: >3, ICM: A/B, TE: A/B according to Gardner Grading System), trophectoderm biopsy was performed on Days 5/6 and embryos were analyzed for chromosomal abnormalities. All embryos were vitrified after biopsy. Statistical analysis was performed using Mann-Whitney test.

Main results and the role of chance

Mean female age was similar between 5% and 3% group (37.76±4.7y vs 38.35±4.19y, p = 0.2263).

Fertilization rates were similar between two groups (81.04% in 5% VS 81.77 in 3%, p = 0.9718). In 5% O2 Group, cleavage rate (98.86%) was found to be significantly higher, compared to 3% O2 Group (96.86%) (p = 0.003). Blastocyst formation rate (expressed per fertilized oocyte) was found to be significantly higher in the 5% O2 Group (76.56 in 5% VS 67.22 in 3%) (p = 0.029), as well as biopsied blastocyst rate (91.9% in 5% VS 82.29% in 3%) (p = 0.0056).

Euploidy rates were found to be similar between the two groups, 26.7 in 5% Group and 26.76 in 3% Group (p = 0.9272). However, more blastocysts were available for biopsy on Days 5/6 in the 5% Group, as shown above.

In the 5% Group, 101 embryotransfers have been performed, 54 with positive βHCG and 42 cycles had no euploid embryos after PGT-A. In the 3% Group, 28 embryotransfers have been performed, 18 with positive βHCG, 7 cycles are pending and 24 had no euploid embryos. This is an ongoing study and clinical outcomes remain to be reported and analyzed after the completion of data selection.

Limitations, reasons for caution

This is a retrospective study in which cycles from the two groups were not performed simultaneously but at different time periods. In addition, all PGT-A cycles were included in the study, regardless the type of infertility (e.g. both male and non-male factor infertility).

Wider implications of the findings

Based on these results, it is not recommended to decrease oxygen tension below 5% during culture, as this does not improve fertilization and euploidy rates. Nevertheless, embryo quality and blastocyst formation was found to be higher in 5% Group and this findings should be confirmed in a larger sample size.

Trial registration number

not applicable

P-160 The effect of laser assisted hatching (AHΑ) on vitrified-warmed blastocysts post warming on reproductive outcome

Study question

Does laser assisted hatching (ΑΗΑ) of vitrified-warmed blastocysts post warming improve the pregnancy rates?

Summary answer

This study suggests that although laser assisted hatching post warming shows a trend towards improving pregnancy rates, the difference is not significant.

What is known already

It is known that vitrification may alter the zona pellucida’s biochemical properties and possibly cause hatching failure and ultimately implantation failure. One proposed way in order to overcome this drawback, is the implementation of laser assisted hatching. During assisted hatching, multiple laser shots are performed in the perivitelline space creating an opening on the zona pellucida which facilitates the blastocyst’s herniation process. The efficiency of this method in regard to pregnancy outcomes though, remains controversial. Some studies report a significantly positive effect on pregnancy outcomes using laser assisted hatching whereas others report no significant difference.

Study design, size, duration

This prospective randomized study was performed at Embryolab Fertility Clinic, in Thessaloniki, Greece between January 2020 and October 2020 and included 2439 frozen embryo transfers. Patients with vitrified-warmed embryos were randomized and allocated to the study (ΑHA) group or control (NO AHA) group.

Participants/materials, setting, methods

Patients were divided in two groups: AΗΑ group (n = 1799) where laser assisted hatching was performed on the day of embryotransfer (Day 3 or Day 5) on the zona of the embryos post warming and control group (n = 640) where the embryos remained untreated after the warming procedure. The 2 groups were further divided in 3 subgroups depending on the women’s’ age (≤35, 36-40, ≥41) and in 2 more subgroups depending on the day of the transfer.

Main results and the role of chance

Mean pregnancy rate for all embryos’ stages in AHA group was 60.03% whereas in the NO AHA group was 58.28% (p = 0.4385). In the subgroup of ≤ 35-years, pregnancy rates were 70.23% and 66.49% respectively (p = 0.3363). In the 36-40years subgroup, rates were 58.24% and 60.09% respectively (p = 0.6418). And finally, in the ≥41-years subgroup, pregnancy rates were 54.26% and 49.79% respectively (p = 0.2331). In the group where the embryos were on cleavage stage, the overall pregnancy rate for the AHA group was 27.46 and for the NO AHA group was 35.42% (p = 0.2957). In the subgroup of ≤ 35-years, pregnancy rates were 44.44% and 58.33% respectively (p = 0.4231). In the 36-40years subgroup, rates were 33.33% and 42.86% respectively (p = 0.5236). And finally, in the ≥41-years subgroup, pregnancy rates were 18.42% and 18.18% respectively (p = 0.9796). In the group where the embryos were on blastocyst stage, the overall pregnancy rate for the AHA group was 62.82% and for the NO AHA group was 60.14% (p = 0.2486). In the subgroup of ≤ 35-years, pregnancy rates were 71.66% and 67.03% respectively (p = 0.2430). In the 36-40years subgroup, rates were 60.16% and 61.31% respectively (p = 0.7786). And finally, in the ≥41-years subgroup, pregnancy rates were 58.37% and 53.08% respectively (p = 0.1763).

Limitations, reasons for caution

Clinical pregnancy rates and live birth rates were not available so as to draw a safer conclusion regarding the effectiveness of the method. In contrast to all kind of cases (both homologous and heterologous cycles) having been pooled together, an appropriate subgrouping might would have been the optimal approach.

Wider implications of the findings

AHA before transfer of vitrified/warmed embryos does not improve pregnancy rates regardless of stage or age. Nevertheless of the trend towards improving pregnancy rates, the difference is not statistically significant. Large scale, well-designed and appropriately subgrouped studies are necessary in order to investigate if this trend can become statistically significant.

Trial registration number

N/A

P-197 Successful implementation of an end-to-end artificial intelligence (AI) platform in a busy IVF clinic: A prospective observational study

Study question

How demanding in terms of time and resource allocation is the full integration of an AI platform to the routine operation of an IVF clinic?

Summary answer

The rapid and effective implementation, and continuous performance, of EMA was qualitatively and quantitatively demonstrated for the first time in a real-world clinical setting.

What is known already

The role of AI-based embryo predictive analysis tools is often hailed as one of the most important recent developments in the IVF clinic. The high precision of such systems has been reported. For instance, the AI-system implemented here, EMATM(AiVF), employs a convolutional neural network architecture, providing an area-under-the-curve (AUC) of 0.95 with 83% accuracy. However, little was reported to date on the full implementation of these advanced systems in the active IVF lab. This study prospectively evaluated the clinical implementation and process-of-use in an IVF clinic of EMA, the first end-to-end AI-driven platform designed to algorithmically aid in evaluating embryos.

Study design, size, duration

A prospective observational single center study. The study was performed in two phases. Phase I: EMA was integrated into standard workflow and qualitatively evaluated over the course of one month by five embryologists in a series of twice-daily qualitative checks and questionaries. Phase II: The rate of agreement between EMA and embryologists were benchmarked and compared to evaluate how the model aids embryologists in efficiently assessing embryos.

Participants/materials, setting, methods

Phase I: Five senior embryologists completed electronic questionaries to qualitatively report on the ease-of-use, functionality, and performance of EMA after using the platform as adjunctive information on 588 embryos; ICSI was performed on all treatment cycles. Phase I was completed within 2 weeks. Phase II: The rate of agreement between five senior embryologists and EMA was calculated for the accuracy in ranking embryo(s) for transfer/freeze (146 treatment cycles). Phase II was undertaken in 4 weeks.

Main results and the role of chance

EMA was effectively incorporated into a busy IVF laboratory for routine daily use to algorithmically assess all embryos at 105 hours post-fertilization prior to vitrification. All embryos were cultured in a time-lapse incubator and successfully evaluated by both EMA and embryologists in parallel to conventional morphologic embryo evaluation. In Phase I, all five embryologists qualitatively approved of EMA’s integration and clinical utility inside their workflow and reported enhanced efficiency when EMA was used per its intended use. In Phase II we demonstrated a 86% agreement rate between embryologists and EMA. Of all embryos selected for transfer by embryologists 100% were also identified by EMA as having the highest potential for implantation. Of all embryos selected for vitrification by embryologists, 85%were identified by EMA as top-quality (Gardner criteria: A/B grade) embryos. Among embryos that were graded C/D (Gardner criteria) by embryologists, 89% were identified by EMA as “low grade” as well. Pregnancies were shown to be highly associated with EMA's embryo selection. The final stage of our implementation analysis of EMA is currently ongoing; the association between the algorithmic outputs of EMA and clinical implantation rates are being investigated in a prospective double-blinded, observation cohort study and results will be presented.

Limitations, reasons for caution

This is a single center study, based on relatively homogenous patient population. Nevertheless, given the impressive results reported herein, we conclude that this single case-study is sufficient for demonstrating rapid and successful implementation and process-validation of EMA for routine use by the clinic.

Wider implications of the findings

AI-based decision support systems like EMA have the potential to increase rapid and objective standardization inside the clinic, thereby improving accurate decision making and saving time and resources without interfering with the busy workflow of an IVF setting. Routine use of EMA in IVF should be prioritized for further evaluation.

Trial registration number

N/A

P–209 Artificial collapse of human expanded blastocysts protects the quality of embryos during vitrification/warming procedure

Study question

Does artificial collapse of human blastocysts before vitrification affect the post warming quality of embryos and/or the reproductive outcome?

Summary answer

This study suggests that artificial collapse with laser pulse before vitrification significantly benefits blastocyst quality post-warming without improving reproductive outcome.

What is known already

The efficiency of vitrification of blastocysts can be influenced by various factors, such as the stage of the expansion and the quality of the embryos. Expanded blastocysts seem to be more sensitive and prone to cryo-injury during vitrification because of the large amount of blastocoelic fluid which may cause insufficient dehydration. Artificial collapse (AC) with micro-needles or with laser pulse can improve the vitrification procedure and protect the expanded blastocysts from cryoinjuries by reducing the fluid of the blastocoel.

Study design, size, duration

This prospective randomized study was performed at Embryolab Fertility Clinic, in Thessaloniki, Greece between July 2020 and November 2020 and included 94 ICSI treatments with no fresh embryo transfer. Patients with more than 4 blastocysts were randomized and allocated to the study (AC) group or control group. Randomization list was created by a computer-based program. The embryos were vitrified at the blastocyst stage and the best 1–2 embryos were transferred in a subsequent cycle.

Participants/materials, setting, methods

Patients were divided in two groups: AC group (n = 46) where 1 or 2 best expanded blastocysts were artificially collapsed by a laser pulse before vitrification and control group (n = 48) where the corresponding best expanded embryos remained untreated before vitrification. The embryos were graded according to Gardner’s criteria and vitrified using open system. Quality of embryos, pregnancy rate and clinical pregnancy rate from the first warming cycle were the parameters that were analyzed using z-test.

Main results and the role of chance

The analyzed embryos were in total 171, 85 in the AC group and 86 in the control group. The day 5 embryos in each group were 6.89 (±3.41) and 6.50 (±3.38) and the number of embryos per embryo transfer was 1.85 (±0.36) and 1.79 (±0.41) respectively. Cryoinjury was determined as the presence of degenerated cell in ICM or TE. In the AC group cryo-injury was significantly lower than in the control group [31.11% with at least 1 embryo per embryo transfer and 52.08% respectively (p = 0.0356), 6.67% with cryo-injury in both embryos and 14.58% respectively (p < 0.0001), 8.89% with cryo-injury in ICM and 10.42% respectively (p < 0.0001), 15.56% with cryo-injury in trophectoderm and 27.08% respectively (p < 0.0001), and 6.67% with cryo-injury in both ICM and trophectoderm and 12.50% respectively (p < 0.0001)]. Pregnancy rate (positive b-hcg) was not significantly different between the two groups (62.22% in AC group and 76.09% in control group, p = 0.1479), nor was the clinical pregnancy rate (52.38% and 60.87% in AC and control group respectively, p = 0.4208).

Limitations, reasons for caution

The number of cases included in this study was limited and the live birth rate was not yet available. More prospective randomized studies are needed in order to validate the benefit of artificial collapse before the vitrification procedure.

Wider implications of the findings: Laser artificial Collapse does not compromise expanded blastocyst quality, on the contrary it seems to reduce the amount of cryoinjury observed post warming. Whether it can improve the reproductive outcome, remains to be examined in larger scale studies.

Trial registration number

Not applicable

Advances in biofeedback and neurofeedback studies on smoking

Smoking is a leading cause of morbidity and premature death constituting a global health challenge. Although, pharmacological and behavioral approaches comprise the mainstay of smoking cessation interventions, the efficacy and safety of pharmacotherapy is not demonstrated for some populations. Non-pharmacological approaches, such as biofeedback (BF) and neurofeedback (NF) could facilitate self-regulation of predisposing factors of relapse such as craving and stress. The current review aims to aggregate the existing evidence regarding the effects of BF and NF training on smokers. Relevant studies were identified through searching in Scopus, PubMed and Cochrane Library, and through hand-searching the references of screened articles. Peer-reviewed controlled and uncontrolled studies, where BF and/or NF training was administered, were included and evaluated according to PICOS framework. Narrative qualitative synthesis of ten eligible studies was performed, aggregated into three categories according to training provided. BF outcomes seem to be affected by smoking behavior prior to training; individualized EEG NF training holds promise for modulating craving-related response while minimizing the required number of sessions. Real-time fMRI NF studies concluded that nicotine-dependent individuals could modulate craving-related brain responses, while mixed results were revealed regarding smokers' ability to modulate brain responses related to resistance towards the urge to smoke. BF and NF training seem to facilitate modulation of autonomous and/or central nervous system activity while also transferring this learned self-regulation to behavioral outcomes. BF and NF training should a) address remaining issues on specificity and scientific validity, b) target diverse demographics, and c) produce robust reproducible methodologies and clinical guidelines for relevant health care providers, in order to be considered as viable complementary tools to standard smoking cessation care.

The peculiar size and temperature dependence of water diffusion in carbon nanotubes studied with 2D NMR diffusion-relaxation D -T 2eff spectroscopy

It is well known that water inside hydrophobic nano-channels diffuses faster than bulk water. Recent theoretical studies have shown that this enhancement depends on the size of the hydrophobic nanochannels. However, experimental evidence of this dependence is lacking. Here, by combining two-dimensional nuclear magnetic resonance diffusion-relaxation ( D - T 2 e f f ) spectroscopy in the stray field of a superconducting magnet and molecular dynamics simulations, we analyze the size dependence of water dynamics inside Carbon Nanotubes (CNTs) of different diameters ( 1.1 - 6.0  nm), in the temperature range of 265 - 305  K. Depending on the CNT diameter, the nanotube water is shown to resolve in two or more tubular components acquiring different self-diffusion coefficients. Most notably, a favorable CNT diameter range ( 3.0 - 4.5  nm) is experimentally verified for the first time, in which water molecule dynamics at the center of the CNTs exhibits distinctly non-Arrhenius behavior, characterized by ultrafast diffusion and extraordinary fragility, a result of significant importance in the efforts to understand water behavior in hydrophobic nanochannels.