From June 2019 to July 2021, the MIT Plasma Science and Fusion Center, in collaboration with Commonwealth Fusions Systems, designed, built, and commissioned a test facility at the Massachusetts ...Institute of Technology to evaluate the performance of a rare-earth-yttrium-barium-copper-oxide-based, 2.9-m tall, 1.9-m wide Toroidal Field Model Coil (TFMC) for the SPARC tokamak. This article presents the facility's supercritical helium (SHe) circulation system design and measured performance. The facility employed a forced-flow SHe circulation loop cooled by cryocoolers to provide a nominal cooling power of 600 W at 20 K and up to 70 g/s SHe flow to the TFMC at an absolute pressure of 20 bar. The reliance on cryocoolers as the facility's cooling source was an ideal arrangement. Procurement costs were modest, acquisition time was reasonable, and seating requirements were minimal. A steady improvement in cryocooler design provided a simple-to-use system with sufficient cooling capacity for our needs. Extensive, closed-loop analyses were performed both to support this procurement and to finalize the overall design of the SHe cooling circuit. The SHe system worked reliably, permitting flexible operation of the TFMC test facility under all working conditions.
— Aims: This study examined the possibility of using hair samples other than scalp hair for analysis of fatty acid ethyl esters (FAEE) as markers for alcohol misuse. Methods: Samples of scalp and ...pubic hair and, if available, axillary, beard and body hair of one teetotaller, five moderate social drinkers and 22 fatalities were analysed for FAEE by head-space solid-phase microextraction and gas chromatography–mass spectrometry. The sum of the concentrations of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate (CFAEE) in the hair samples was compared with information about the drinking behaviour of the individuals. Results: Although there were large differences in the analyte concentrations in hair from different sites in the same individual, cases of chronic excessive alcohol consumption were characterized by CFAEE > 1.0 ng/mg in almost all samples. Conclusion: FAEE concentrations in hair other than scalp hair can be used as markers of chronic alcohol misuse.
This paper presents design, fabrication, and operational results for a novel pair of binary Current Leads (CLs). The CLs were purpose built for the SPARC Toroidal Field Model Coil (TFMC) Test ...Facility at the MIT Plasma Science and Fusion Center (PSFC). The CLs operate stably at current ramp rates up to 50 kA/s and steady-state currents of 50 kA from ambient temperature power supplies to the facility's 20 K test environment. The CLs have three main sections: an upper copper heat exchanger (HEX) cooled with gas nitrogen (GN2) which connects to room temperature power supply (PS); a central liquid nitrogen (LN2) boiling chamber (BC) which vents into the HEX; and a lower Rare Earth Yttrium Barium Copper Oxide (REBCO) Section. The CLs have three distinguishing features: the BCs high surface area maintains <1 K temperature difference between their surfaces and the nucleate boiling LN2 within; each REBCO section is composed of six parallel "petals" that were individually qualified prior to installation; indium seals were used to simultaneously provide electrical continuity and hermetic sealing which enabled fabrication without need for braze or electron beam welding qualification processes. Additionally, the CLs can reduce the LN2 boiling pressure and thus temperature which significantly improves the temperature margins within the REBCO Section. The CLs were designed and built within 1.5 years and used successfully to deliver 40.5 kA of current to the SPARC TFMC. Since then they have been thermally cycled over 10 times and operated at both 1 atm and 0.65 atm.
In this article, the SPARC Toroidal Field Model Coil (TFMC) experimental tests are described. The tests include detailed comparisons to a hierarchy of electromagnetic and structural models of the ...coil. The tests confirm the ability of the no-insulation no-twist (NINT) configuration to provide highly stable dc operations with peak magnetic field in excess of 20 T at the rare earth yttrium barium copper oxide (REBCO) tape stacks. The advantages of the modular TFMC approach are validated including the ability to test and probe the REBCO and structural response of the coil in stages, a strategy that will be applied to large-scale coil production for SPARC. The electromagnetic models show high fidelity agreement to the dc and charging coil performance in terms of current distribution, voltages, and heating. The transient response of the TFMC to open-circuit events is examined. The coil exhibits the positive features of the NINT design with very low induced voltages and a predictable redistribution of current and resulting volumetric heating. However, highly localized damage occurs during a programmed open circuit at operational conditions similar to those used in the SPARC tokamak, in agreement with calibrated electromagnetic models. This reveals the cause and remedy to the thermal instability that gives rise to the damage. Therefore, the conclusion of the tests is that the NINT TFMC is confirmed as meeting the programmatic requirements for SPARC and, more generally, for high-field tokamaks.
Abstract
STUDY QUESTION
Is the fetal fraction (FF) of circulating cell-free DNA (cfDNA) affected in pregnancies following ART treatment with either fresh or frozen embryo transfer (ET) compared with ...natural conception?
SUMMARY ANSWER
This study shows a significant reduction in the FF in ART patients compared with naturally conceived pregnancies, which seems to be more pronounced after fresh ET compared with frozen ET.
WHAT IS KNOWN ALREADY
Non-invasive prenatal testing (NIPT) is based on cfDNA in maternal blood, of which about 10% is of placental origin and thus represents the fetal karyotype. Validation studies have demonstrated a high sensitivity, specificity and positive predictive value of NIPT for the detection of fetal trisomy 21, 18 and 13. Nevertheless, the FF of cfDNA is an important factor for NIPT test accuracy. Several studies have found a reduction in FF for pregnancies following ART in comparison with natural conception. However, knowledge on how the FF is affected in ART pregnancies after fresh ET compared with frozen ET is very limited.
STUDY DESIGN, SIZE, DURATION
The study was designed as a case–control study. A total of 54 women with an ongoing pregnancy following ART treatment were included. After exclusion for different reasons, statistical analyses were based on 23 NIPT samples from pregnant women treated with fresh ET and 26 NIPT samples from pregnant women treated with frozen-thawed ET in a modified natural cycle. Women were included between February 2018 and November 2018. The results were compared with a control group of 238 naturally conceived pregnancies with a high-risk result from the combined first trimester screening (cFTS).
PARTICIPANTS/MATERIALS, SETTING, METHODS
The study included women from the Fertility Clinics at Copenhagen University Hospital Hvidovre and Copenhagen University Hospital Rigshospitalet. Blood samples for NIPT analysis were drawn between 11 + 0 and 14 + 2 weeks of gestation and were all analyzed at the NIPT Center at Copenhagen University Hospital Hvidovre. The NIPT-test was performed by massive-parallel whole-genome sequencing. The FF was determined using the SeqFF algorithm.
MAIN RESULTS AND THE ROLE OF CHANCE
We found a reduction in FF in ART patients compared with naturally conceived pregnancies, and the reduction was more pronounced for ART pregnancies after fresh ET (mean FF = 0.049) compared with frozen ET (mean FF = 0.063) (multivariate analysis adjusted for maternal BMI, P = 0.02). Another multivariate analysis, adjusted for BMI and multiples of median (MoM) values for pregnancy-associated plasma protein-A (PAPP-A), demonstrated a significantly reduced FF for ART pregnancies (mean FF = 0.056) compared with naturally conceived pregnancies (mean FF = 0.072) (P < 0.0001). We found that FF was significantly reduced with increasing maternal BMI (P < 0.0001) and with decreasing MoM values of PAPP-A (P = 0.003).
LIMITATIONS, REASONS FOR CAUTION
A limitation of our study design was the relatively small sample size. Another limitation was that the control group was not matched with the ART-treated women. The majority of the women from the control group had a high risk from cFTS, thereby their biochemical markers were diverging. However, the biochemical markers for the ART-treated women with fresh or frozen ET were not divergent within the subgroups.
WIDER IMPLICATIONS OF THE FINDINGS
Concurrent with other studies demonstrating a reduced FF for singleton pregnancies after ART treatment compared with naturally conceived pregnancies, we found a reduction in FF between the two groups. This is one of the first studies to examine FF in ART pregnancies after fresh ET compared with frozen ET, hence the existing knowledge is limited. We find that FF is even more reduced in pregnancies following fresh ET compared with frozen ET, which might possibly reflect the predisposition of being small for gestational age after fresh ET compared with natural cycle frozen ET.
STUDY FUNDING/COMPETING INTEREST(S)
The study was supported by the A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal (the A.P. Møller Foundation for General Purposes). All authors declare no conflicts of interest.
TRIAL REGISTRATION NUMBER
NA.
The authors suggest a procedure for the determination of the natural nuclear magnetic resonance line width Δ
ν of liquids using an air coil system at flux densities from 25
μT to 150
μT. Even if the ...line broadening caused by instrumental field inhomogeneity is much higher than Δ
ν, Δ
ν can be found by extrapolating the measured line width’s field dependency. For pure water this procedure yielded Δ
ν
=
0.125
Hz
±
0.005
Hz. This is shown to be consistent with the smallest line width found for this sample below 25
μT using a superconducting quantum interference device-based spectrometer.
Adipose tissue is a major endocrine organ, releasing signaling and mediator proteins, termed adipokines, via which adipose tissue communicates with other organs. Expansion of adipose tissue in ...obesity alters adipokine secretion which may contribute to the development of metabolic diseases. Consequently, this correlation has emphasized the importance to further characterize the adipocyte secretion profile, and several attempts have been made to characterize the complex nature of the adipose tissue secretome by utilizing diverse proteomic profiling approaches. Although the entirety of human adipokines is still incompletely characterized, to date more than 600 potentially secretory proteins were identified providing a rich source to identify putative novel biomarkers associated with metabolic diseases.
Radiation damage evaluations have been performed with the ACAB code for fusion-relevant materials in an Ignitor-like compact fusion device that could be used as a neutron source for materials ...testing. Values ranging from 1.6
×
10
−26 to 2.4
×
10
−25
dpa per source neutron have been obtained, which translates into 16–250
dpa/y at full operating power and demonstrates the potential of this neutron-rich device for fusion materials testing. It will be shown that only a few full-power months of operation with a feasible operating duty cycle are sufficient to obtain relevant radiation damage values in terms of dpa. An estimate of the radiation damage on selected machine components will be presented, and solutions to solve the problem of radiation damage to the insulator of the toroidal field insulator will be discussed.
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