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Since 2005, I have had the pleasure of serving as the Chief Technical Editor for the CEC portion of Advances in Cryogenic Engineering. Starting with the 2025 conference, this role will be taken on by Ram Dhuley of Fermilab. I will remain involved as one of the technical subeditors. I have greatly enjoyed serving in this role and appreciate Ram’s willingness to take on this task. I wish him all the best in this important work and know that he will do an excellent job. I wish to thank all the technical subeditors, reviewers and authors who have contributed to Advances over the years. Special thanks go to Balu Balachandran, the Chief Technical Editor of the ICMC portion of Advances and to Annett Cady of Centennial Conferences who has done outstanding work as Managing Editor during my tenure. All of the above have helped make Advances in Cryogenic Engineering one of the premier, archival sources of information in cryogenic engineering. I look forward to continuing this exciting work with you. J. G. Weisend II January 2024

Owing to superior physio-chemical characteristics, titanium alloys are widely adopted in numerous fields such as medical, aerospace, and military applications. However, titanium alloys have poor machinability due to its low thermal conductivity which results in high temperature during machining. Numerous lubrication and cooling techniques have already been employed to reduce the harmful environmental footprints and temperature elevation and to improve the machining of titanium alloys. In this current work, an attempt has been made to evaluate the effectiveness of two cooling and lubrication techniques namely cryogenic cooling and hybrid nanoadditive–based minimum quantity lubrication (MQL). The key objective of this experimental research is to compare the influence of cryogenic CO 2 and hybrid nanofluid–based MQL techniques for turning Ti–6Al–4V. The used hybrid nanofluid is alumina (Al 2 O 3 ) with multi-walled carbon nanotubes (MWCNTs) dispersed in vegetable oil. Taguchi-based L9 orthogonal-array was used for the design of the experiment. The design variables were cutting speed, feed rate, and cooling technique. Results showed that the hybrid nanoadditives reduced the average surface roughness by 8.72%, cutting force by 11.8%, and increased the tool life by 23% in comparison with the cryogenic cooling. Nevertheless, the cryogenic technique showed a reduction of 11.2% in cutting temperature compared to the MQL-hybrid nanofluids at low and high levels of cutting speed and feed rate. In this regard, a milestone has been achieved by implementing two different sustainable cooling/lubrication techniques.

High-entropy alloys are equiatomic, multi-element systems that can crystallize as a single phase, despite containing multiple elements with different crystal structures. A rationale for this is that the configurational entropy contribution to the total free energy in alloys with five or more major elements may stabilize the solid-solution state relative to multiphase microstructures.We examined a five-element high-entropy alloy, CrMnFeCoNi, which forms a single-phase face-centered cubic solid solution, and found it to have exceptional damage tolerance with tensile strengths above 1 GPa and fracture toughness values exceeding 200 MPa·m1/2. Furthermore, its mechanical properties actually improve at cryogenic temperatures; we attribute this to a transition from planar-slip dislocation activity at room temperature to deformation by mechanical nanotwinning with decreasing temperature, which results in continuous steady strain hardening.

Introduction/Background*Transvaginal ultrasound scanning (TVUS) to measure the endometrial thickness (ET) has historically been recommended as a first-line investigation of patients with postmenopausal bleeding. The aim of the study was to determine the diagnostic performance of endometrial thickness measured by transvaginal sonography in diagnosing endometrial cancer in patients presenting with post-menopausal bleeding.MethodologyThe databases of the Department of Gynecological Oncology at the University Clinic of Gynecology and Obstetrics in Skopje, in the period January – December 2015 were searched in order to identify patients that underwent endometrial sampling due to newly-diagnosed postmenopausal bleeding. The following data were extracted from the patient records: age at sampling, age at menopause, parity, body mass index (BMI), American Society of Anesthesiologists physical status rating (ASA), history of hypertension and diabetes, endometrial thickness and the histology from the endometrial sampling. The endometrial thickness measurement was acquired in the mid sagittal plane at the thickest part. All patients underwent D&C, with optional previous hysteroscopic evaluation (at he discretion of the attending) under general anesthesia.Result(s)*A total of 158 patient records that met the criteria were identified. The prevalence of endometrial cancer was 15.2%. Endometrial thickness was a statistically significant independent predictor of the presence of endometrial cancer and atypical endometrial hyperplasia (OR 1.19 95% CI 1.09-1.29 for each 1mm increase in thickness, p<0.001). The ROC curve analysis in our study had an AUC of 0.83 (p<0.001) and identified a cut-off level for endometrial thickness of 8mm which was associated to a sensitivity of 88.9%, specificity of 65.6%, PPV of 34.8% and NPV of 96.6% for the detection of endometrial cancer. Using a cut-off for endometrial thickness of ≤3mm achieved 100% sensitivity.Conclusion*None of the analyzed cut-off points for endometrial thickness achieved optimal diagnostic accuracy, as all cut-off values associated to sensitivity rates above 95% had false positive rates of over 60%. Nevertheless, an endometrial thickness cut-off of 3mm, due to the associated high sensitivity, can safely be used to identify women with postmenopausal bleeding who are highly unlikely to harbor endometrial cancer and that can forego initial endometrial sampling.

The deep cryogenic temperatures encountered in aerospace present significant challenges for the performance of elastic materials in spacecraft and related apparatus. Reported elastic carbon or ceramic aerogels overcome the low-temperature brittleness in conventional elastic polymers. However, complicated fabrication process and high costs greatly limited their applications. In this work, super-elasticity at a deep cryogenic temperature of covalently crosslinked polyimide (PI) aerogels is achieved based on scalable and low-cost directional dimethyl sulfoxide crystals assisted freeze gelation and freeze-drying strategy. The covalently crosslinked chemical structure, cellular architecture, negative Poisson’s ratio (−0.2), low volume shrinkage (3.1%), and ultralow density (6.1 mg/cm 3 ) endow the PI aerogels with an elastic compressive strain up to 99% even in liquid helium (4 K), almost zero loss of resilience after dramatic thermal shocks (∆ T  = 569 K), and fatigue resistance over 5000 times compressive cycles. This work provides a new pathway for constructing polymer-based materials with super-elasticity at deep cryogenic temperature, demonstrating much promise for extensive applications in ongoing and near-future aerospace exploration. The deep cryogenic temperatures present significant challenges for the performance of elastic materials. Here, the authors present a low density covalently crosslinked polyimide (PI) aerogels with super-elastic properties at deep cryogenic temperatures.

Owing to poor thermal conductivity, heat dissipation, and high chemical reactivity toward most of the tool materials, temperature elevation in the machining of titanium alloy leads to poor surface quality. Based on analyzing the variation laws of the milling forces under cryogenic cooling, the present investigation concerns the surface integrity (surface roughness, micro-hardness, microstructures, and residual stresses) in cryogenic milling of Ti-6Al-4 V alloy under the application of liquid nitrogen (LN 2 ) as a cooling mode. Findings have indicated a dramatic increase in milling forces, and decreasing surface roughness was observed under variation of jet temperature (20~−196 °C). Besides an increase in cutting speed from 60 to 120 m/min, a linear increase in cutting forces, surface roughness, micro-hardness, and residual compressive stress was observed. The minimum micro-hardness decreased at cutting speed of 90 m/min and up to 30 μm in depth. A holistic comparison between obtained results under cryogenic milling and previously studied results under dry milling at same cutting conditions depicted higher micro-hardness and higher compressive residual stress under cryogenic LN 2 on the machined surface. However, the residual stress under LN 2 cooling conditions tends to decrease relatively slower compared to dry milling. Also, there are no significant differences in grain refinement and twisting under dry and cryogenic LN 2 machining. The research work proves the effectiveness of cryogenic milling in improving the surface integrity of the Ti-6Al-4 V alloy.

Photonic integrated circuits (PICs) operating at cryogenic temperatures are fundamental building blocks required to achieve scalable quantum computing and cryogenic computing technologies 1 , 2 . Silicon PICs have matured for room-temperature applications, but their cryogenic performance is limited by the absence of efficient low-temperature electro-optic modulation. Here we demonstrate electro-optic switching and modulation from room temperature down to 4 K by using the Pockels effect in integrated barium titanate (BaTiO 3 ) devices 3 . We investigate the temperature dependence of the nonlinear optical properties of BaTiO 3 , showing an effective Pockels coefficient of 200 pm V −1 at 4 K. The fabricated devices show an electro-optic bandwidth of 30 GHz, ultralow-power tuning that is 10 9 times more efficient than thermal tuning, and high-speed data modulation at 20 Gbps. Our results demonstrate a missing component for cryogenic PICs, removing major roadblocks for the realization of cryogenic-compatible systems in the field of quantum computing, supercomputing and sensing, and for interfacing those systems with instrumentation at room temperature. The integration of barium titanate thin films with silicon-based waveguides enables the operation of efficient electro-optic switches and modulators at temperatures as low as 4 K, with potential applications in quantum computing and cryogenic computing technologies.

Ni-based superalloy GH4169 is widely demanded in the aerospace industry because of its excellent properties. However, the cutting of GH4169 at normal temperature has many challenges, such as tool wear, machining accuracy, and production efficiency. Cryogenic cutting has been an advanced method in assisting material removal machining. This paper focused on the cryogenic cutting performance of GH4169 at different initial temperatures, namely, 20 °C, −30 °C, −80 °C, and –130 °C. Firstly, the cryogenic mechanical properties of GH4169 were obtained by the Hopkinson pressure bar test at speed of 12 m/s and 18 m/s. The obtained data was used to analyze the cryogenic cutting performance of GH4169 at evaluated temperatures. The single factor milling experiments of GH4169 were carried out at room temperature and evaluated cryogenic levels, and the cutting performance in terms of cutting chips, cutting forces, and tool wear was investigated. The results showed that cryogenic cooling at −130 °C could increase the shear yield strength of the GH4169 by around 19.80% and the length of the cutting chip decreased monotonically by 53.45% compared with the length at room temperature. However, the cutting forces were not monotonically decreased. The cutting forces increased with the decrease of temperature when the initial temperature varied from 20 to −80 °C. However, when the initial temperature further dropped to –130 °C, the cutting forces were reduced by 30.60% for Fx , 24.02% for Fy , and 16.15% for Fz , respectively. Similarly, tool wear at the rake face and flank face is the most severe at –80 °C and the least at –130 °C. The average wear bandwidth at room temperature is 92.06 μm and decreases to 83.358 μm at –130 °C, which is reduced by 9.45%.

The 2019 Cryogenic Engineering Conference Board of Directors list is available in the pdf.