bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Vitro Evaluation of the Hemolytic Effects of Augmented Venous Drainage
Authors: Mathews Randall K. , Sistino Joseph J.
Published: August 2023

Augmentation of venous drainage with either kineticassisted drainage (KAVD) or vacuum-assisted (VAVD) has been used clinically in order to overcome added venous resistance due to smaller venous cannulae or tubing. This in-vitro study evaluates the extent of hemolysis and sub-lethal red blood cell membrane damage than occurs with augmented (kinetic or vacuum) when compared to conventional gravity drainage. Four trials were conducted using each test circuit. The circuits were primed with 6 liters of fresh heparinized bovine blood, which was diluted to a hematocrit of 32% and was recirculated at 5 L/min for 8 hours. Hemolysis was determined by the change in plasma free-hemoglobin (Hb), hematocrit, and potassium at two hour intervals. The red cell osmotic fragility index was used to quantify the sub-lethal red blood cell membrane damage and was also measured every two hours. After 8 hours, the mean +/− SD of the plasma free-Hb were: 96.27 +/− 69.45 mg/dl for gravity, 83.87 +/− 48.14 mg/dl for vacuum-assist, and 134.45 +/−83.78 mg/dl for kinetic-assist. Two-hour increases in the plasma free-Hb revealed the following median values (mg/dL/2h): 16.90 for gravity, 13.75 for vacuum–assist, and 19.40 for kinetic-assist.

Analysis of the two-hour increases in plasma free-Hb with Kruskal-Wallis One-Way ANOVA did not reveal a significant difference among the groups. After 8 hours, the red cell osmotic fragility test results at the 0.55% sodium chloride concentration were compared. The medians of the percent hemolysis were 52.67% for gravity, 49.8% for vacuum-assist, and 57.2% for kinetic- assist. Analysis with the Kruskal-Wallis Wallis One-Way ANOVA did not reveal a significant difference among the groups. Therefore, there is no significant increase in hemolysis or sub-lethal red blood cell membrane damage associated with the use of augmented venous drainage.
The Influences of NO and Ach on cGMP Levels in Two Patient Populations
Authors: Jiang Zhen , Lei Ye , Gu Kefang , Xianghua Jin , Liming Xia , Kejian Hu
Published: August 2023

Pulmonary hypertension following cardiac surgery is an important factor affecting postoperative mortality, and its mechanism has not been thoroughly clarified. Cardiopulmonary bypass (CPB) can destroy pulmonary endothelium and aggravate pulmonary hypertension. This study is designed to investigate the impacts of CPB on vascular endothelium-dependent relaxation, and the relations of CPB to pulmonary hypertension. Forty patients undergoing valve surgery were involved. According to their preoperative pulmonary arterial pressure (PAP), these patients were divided into pulmonary hypertension group (H group) and normal group (N group). The concentrations of cyclic guanosine monophosphate (cGMP) were measured at baseline conditions, after acetylcholine (Ach) injection, and during nitric oxide (NO) inhalation. Samples were taken before sternotomy and after weaning from CPB, 4 and 12 hours post-CPB. At baseline, the level of cGMP in the H group was lower than that of the N group by 33.9% before CPB. After initiating the CPB, although the level of cGMP continuously decreased in both groups until weaning from CPB (the N group decreased 33.3%, and the H group decreased 59%). At that point cGMP was higher in N group than in the H group (p < .01). The level of cGMP of both groups tended to recover 4 hours after CPB, but only the N group returned to baseline 12 hours after CPB. After injection of Ach, the level of cGMP of both groups followed the same change as in the baseline, except with different numeric value. The level of cGMP in N group rose ranging from 160.0–197.3%, while it rose ranging from 87.7–168.1% in H group. The levels of cGMP were higher in N group than those in H group at all times following injection of Ach (61.4, 173.3, 202.7, and 188.0%)(p < .01). After inhalation of NO, the level of cGMP of both groups followed the same change as the baseline. The level of cGMP in N group rose ranging from 194.8–320.5%. Although the levels of cGMP were higher in N group than those in H group (6.9, 25.3, 23.3, and 16.6%), significant differences were achieved at the 4 and 12 hour post-CPB periods (p < .05 or p < .01, respectively). It was concluded that the injury of vascular endothelial function caused by CPB was more critical in pulmonary hypertension patients.
Effects of Ultrafiltration on Enoxaparin: An In Vitro Analysis
Authors: Kohtz Ryan J. , Petterson Craig M. , Mills Nancy J. , Kmiecik Scott A. , Liu Jun-Li , Nichols Jeffery D. , Vaadia Tal S. , Stammers Alfred H.
Published: August 2023

The use of low molecular weight heparins (LMWH) as an anticoagulant in the heparin-resistant patient poses challenges during cardiopulmonary bypass (CPB). The ultrafiltrability of LMWH has not been previously examined. The purpose of this study was to determine the effects of continuous ultrafiltration on the concentraton of a LMWH, enoxaparin. An in vitro analysis was performed using fresh whole human blood and an extracorporeal circuit containing four parallel ultrafiltrators and a cardiotomy reservoir with an integrated heat exchanger. Constant conditions included temperature (37°C), flow (0.20 L-min−1) transmembrane pressure (200 mmHg), and hematocrit (25 ± 2%). Samples were collected at the inlet, outlet, and ultrafiltrate line at one and three min for one control trial and again for each of the four hemoconcentrators following the bolus of enoxaparin. Coagulation measurements included a viscoelastic monitor (TEG), activated clotting time (ACT), activated partial thromboplastin time (aPTT), and quantitative analysis utilizing a membrane-based electrode for potentiometric measurement of polyanionic concentrations of enoxaparin. Enoxaparin concentration, from inlet to outlet, increased from 2.95 ± 0.64 to 5.89 ± 0.95 (p < .001) at 1 min and 4.24 ± 0.49 to 7.89 ± 0.606 (p < .001) at 3 min. Kinetic clot activity, as assessed by the TEG index, decreased from −3.8 ± 2.5 vs. −10.5 ± 6.0; (p < .01) pre- to postultrafiltrator samples after 3 min. ACT and aPTT results demonstrated no significant change. In conclusions, this study demonstrates enoxaparin is concentrated with the use of continuous ultrafiltration. Functional coagulation studies also indicate a concentrating effect, primarily via the TEG.
Assessment of the Resonance Thromboelastograph CS-3 for Differentiation of Coagulation Disorders: A Pilot in vitro Investigation of Simulated Post-Cardiopulmonary Bypass Coagulopathies
Authors: Koster Andreas , Hansen Roland , Schulz Jürgen , Kukucka Marian , Fischer Thomas , Kuppe Hermann
Published: August 2023

Resonance thromboelastography (RTG), a further development of the thromboelastogram (TEG), has been designed for improved differentiation of the effect of the plasmatic coagulation factors (increasing F-leg) and platelets (decreasing P-leg) on clot formation. It is based on the effect of clot elasticity on the resonance of a swinging wire. We assessed the RTG for its ability to differentiate coagulation disorders that frequently occur after cardiac surgery.

The RTG was performed with a CS-3 Analyzer. Samples from 10 healthy volunteers were investigated after the following preparations: (1) baseline values, (2) dilution to a hematocrit of 30% and 20% with either hydroxyl ethyl starch (HES) 10% or plasma; (3) addition of 0.25, 0.5, and 1.0 IU/mL porcine heparin with and without heparinase; and (4) addition of 1.0, 3.0, 4.0, and 5.0 µg/mL of the antiplatelet agent abciximab (ReoPro™). Increasing concentrations of abciximab led to a slower decrease or in the case of higher concentrations, to a persistent elevation of the platelet leg of the RTG. Dilution of the hematocrit with plasma had no effect on the fibrin and platelet leg; whereas, dilution with HES 10% led to an inhibition of the fibrin and platelet leg. Dilution of the plasmatic coagulation factors resulted in an inhibition of both the fibrin and the platelet leg. The addition of 0.25 and 0.5 IU/mL of heparin led to an increased coagulation time and inhibition of the fibrin and platelet legs. These effects were eliminated by the addition of heparinase. The RTG enables the evaluation of platelet function under the condition of a nonimpaired plasma coagulation system. Depletion of plasma coagulation factors and the administration of small amounts of heparin do not enable the distinction between residual effects of an anticoagulant, coagulation factor deficiency, or impaired platelet function. However, the heparin effects can be eliminated by the addition of heparinase. Further improvement may be achieved using a modified RTG by adding plasma coagulation factors in one channel for an improved evaluation of platelet function, even under the condition of a loss of procoagulants.
Chimeric Pig Hearts Resist Hyperacute Rejection in ex vivo Perfusion Model
Authors: Yang Tianyu , Stammers Alfred , Jiang Jun , Shearon Carson , Thompson Scott , Beschorner William E.
Published: August 2023

With surrogate tolerogenesis, the recipient immune system is engrafted within the donor pig before organ transplant. Chimeric pig hearts may resist hyperacute rejection by inducing accommodation. This hypothesis was tested using an ex vivo isolated piglet heart perfusion model. Processed sheep marrow was infused into fetal pigs at 45 days gestation. Heart explants from chimeric or nonchimeric pigs were suspended in a Langendorff apparatus and perfused with plasma from unsensitized sheep or sensitized sheep. Nonchimeric hearts perfused with plasma from unsensitized functioned for 240 min (N = 3). Nonchimeric hearts perfused with sensitized plasma deteriorated rapidly, functioning at 19 ± 12 min (N = 6); Immunohistochemistry of heart graft revealed extensive deposition of IgG, IgM in the microvascular. In contrast, chimeric hearts perfused with sensitized plasma functioned for 183 ± 46 min (N = 3)(p <.001); Deposition of IgG, IgM had substantially less. Heart grafts procured from chimeric pigs survived in the presence of antidonor IgG, IgM, and complement, demonstrating that chimeric pig hearts resist hyperacute rejection.
The Effect of PaCO2 on Cerebral Perfusion: An Experimental Swine Model
Authors: Trowbridge Cody C. , Stammers Alfred H. , Niimi Kevin S. , Glogowski Kimberly R. , Tremain Kimberly D. , Muhle Michelle L.
Published: August 2023

Adequate cerebral perfusion is of particular concern to the clinician and is a major factor in postoperative morbidity. Cerebral circulation has the ability to autoregulate blood flow in order to maintain nutrient delivery and prevent high intravascular pressures. The focus of this study was to characterize the impact of gradually changing arterial CO2 levels on cerebral perfusion. A total of eight porcine subjects were placed into either a normothermic group (NG, N = 4, rectal temperature = 35.4 ± 1.2° C) or a hypothermic group (HG, N = 4, 30.6 ± 0.6° C). After initiation of cardiopulmonary bypass, the PaCO2 values sequentially varied between 24 and 56 mmHg. Arterial, venous, and internal jugular blood gas data were collected at 4 mmHg increments, and relative cerebral blood flow was calculated as CBF = 1 (CarterialO2–CjugularO2)−1 Physiological parameters were similar in both groups across all test conditions: mean arterial pressure— NG 81.6 ± 11.9 mmHg versus HG 73.4 ± 7.0 mmHg, p = NS, and systemic oxygen consumption—HG 110.6 ± 30.0 mL min−1 versus NG 136.4 ± 37.9 mL min−1, p = NS. No significant differences were found in CBF in the NG (21.8 ± 4.4 mL min−1 100 gL at PaCO2= 56 mmHg versus 20.5 ± 5.0 mL min−1 100 g−1 at PaCO2 = 24 mmHg) or the HG (24.3 ± 9.5 mL min−1 100 g−1 at PaCO2 = 56 mmHg versus 25.6 ± 12.0 mL min−1 100 g−1 at PaCO2 = 24 mmHg). In conclusion, the alteration of PaCO2 under both hypothermic and normothermic conditions resulted in no significant differences in 1 (CarterialO2 – CjugularO2)−1 in this model.
Status of Pediatric Perfusion Education: 2000 Survey
Authors: Angona Ron , Searles Bruce , Nasrallah Fadi , Darling Edward
Published: August 2023

In recent years, studies have raised questions about pediatric perfusion training, minimum proficiency requirements, and specialization. To understand these questions better, a survey was undertaken to investigate the status of pediatric/ neonatal perfusion training in the United States. Three groups were surveyed: program directors (PD), recent graduates of perfusion programs (RG), and pediatric cardiac anesthesiologists (PCA). Program directors and recent graduates were queried about didactic curriculum and clinical experiences. All three groups were asked core questions regarding minimum proficiency, specialization, and need for a postgraduate style program. Didactically, 65% of program directors believed that perfusion programs provided a solid introductory knowledge base in infant perfusion. Clinically, students performed an average of 124 ± 42.5 adult and 17 ± 12.9 pediatric cases during their education. Program directors cited numerous limitations to clinical pediatric education, including access to pediatric cases and allocation of resources. The PD (69%) and RG (96%) both believed graduates were less prepared to perform infant/pediatric cardiopulmonary bypass (CPB) at graduation as compared to adult CPB. The opinions of all three groups were divided when asked whether the essentials and guidelines requirement for minimum pediatric caseload is too low (yes response: PD 52%, RG 73%, PCA 47%). The PD and RG were against pediatric subspecialization/certification (87%, 57% respectively); whereas, the PCA were unanimously in favor (100%) of pediatric subspecialization/ certification for perfusionist. All three groups felt a postgraduate-style program in infant perfusion would benefit the community (78%, 82%, 100%). Finally, 64% of RG said that, if available, they would have considered entering a training program in pediatric/neonatal perfusion after graduation. Our results indicate that there are still limitations to pediatric perfusion education. A postgraduate-style program in infant perfusion is one possible solution to this problem.
Penetrating Injury to the Heart Requiring Cardiopulmonary Bypass: A Case Study
Authors: Webb David P. , Ramsey James J. , Dignan Rebecca J. , Drinkwater Davis C.
Published: August 2023

Penetrating wounds to the heart represent a significant surgical challenge because of their unique clinical course and the need for emergent operative care. This operative care, which may include cardiopulmonary bypass (CPB), must be initiated in a prompt yet careful fashion to optimize outcome, while minimizing morbidity. Trauma, because of its unpredictable and nonroutine nature, may present many challenges to the perfusionist in an attempt to anticipate surgical needs and requirements. In this case report, we describe the successful surgical repair of a cardiac nail gun injury, as well as strategies we feel are essential for the safe, successful, and timely application of emergent CPB.
How we achieve satisfaction in training – A German-wide survey on preferred training conditions among trainers and trainees for board certification in gastroenterology
Authors: Schlosser Sophie , Garbe Jakob , Hamesch Karim , Dimitriadis Stavros , Staudacher Jonas Jaromir
Published: August 2023

Background a majority of resident physicians in Germany are not satisfied with their training conditions. However, training satisfaction is important for physician retention and patient care. Although federal and state laws define the general training regulations and conditions, considerable variability still exists concerning their implementation in the healthcare units. Little is known about the expectations concerning training for gastroenterology board certification by trainers and trainees in Germany. This lack of data hinders discussion on and improvement of training in gastroenterology in Germany.

Aim assessment of preferred training conditions among trainers and trainees for board certification in gastroenterology in Germany.

Methods an anonymous, voluntary survey consisting of single- and multiple-choice questions utilizing the Likert scale and fill-in responses was circulated to all members of the German Society for Digestive and Metabolic Diseases (DGVS – Deutsche Gesellschaft für Gastroenterologie, Verdauungs und Stoffwechselerkrankungen), as well as through the student council mailing lists of all German medical schools. The survey aimed to assess the consent regarding the ideal implementation of training regulations for gastroenterology board certification. Department heads, senior physicians, board-certified physicians, and outpatient-care physicians were classified as trainers and residents and students as trainees. Subgroups defined by place of work, age, gender, professional position, employment status, and parental status were investigated.

Results 958 responses were included in the final analysis. We found a broad consensus among trainers and trainees on most aspects of our survey. Considerable differences were seen in items on part-time work, overtime, protected time for research, and advanced endoscopy training.

Conclusion the broad consensus seen in this survey is indicative of a shared vision for training conditions among trainers and trainees. However, the areas of dissent identified in this survey may assist trainers to better understand the expectations of trainees. Furthermore, this survey creates a sound basis upon which training conditions for board certification in gastroenterology in Germany can be discussed and improved.
Notstromversorgung: Ohne Panik resilient bleiben
Authors: Lang Michael
Published: August 2023

Wie sehr Krankenhäuser auf elektrische Energie angewiesen sind, macht sich spätestens bei einem Stromausfall bemerkbar. Die Fachvereinigung Krankenhaustechnik hat sich zum Ziel gesetzt, die Verantwortlichen in den Kliniken für dieses wichtige Thema zu sensibilisieren.
Sicherheit im Gesundheitswesen: Überwachung sensibler Bereiche
Authors: Strübel Markus
Published: August 2023

Zur Sicherheit im Krankenhaus gehören Maßnahmen wie die Zutrittskontrolle, aber auch das Erkennen von möglichen Gefahren im Vorfeld beispielsweise mittels Videoüberwachung. Moderne Videosicherheitssysteme ermöglichen die Wahrung der Privatsphäre und die Einhaltung des Datenschutzes.
Isotope effects on energy transport in the core of ASDEX-Upgrade tokamak plasmas: Turbulence measurements and model validation
Authors: Molina Cabrera P. A. , Rodriguez-Fernandez P. , Görler T. , Bergmann M. , Höfler K. , Denk S. S. , Bielajew R. , Conway G. D. , Yoo C. , White A. E. ,   ASDEX Upgrade Team
Published: August 2023

Design and operation of future tokamak fusion reactors using a deuterium–tritium 50:50 mix requires a solid understanding of how energy confinement properties change with ion mass. This study looks at how turbulence and energy transport change in L-mode plasmas in the ASDEX Upgrade tokamak when changing ion species between hydrogen and deuterium. For this purpose, both experimental turbulence measurements and modeling are employed. Local measurements of ion-scale (with wavevector of fluctuations perpendicular to the B-field k⊥< 2 cm−1, k⊥ρs< 0.2, where ρs is the ion sound Larmor radius using the deuterium ion mass) electron temperature fluctuations have been performed in the outer core (normalized toroidal flux ρTor=0.65−0.8) using a multi-channel correlation electron cyclotron emission diagnostic. Lower root mean square perpendicular fluctuation amplitudes and radial correlation lengths have been measured in hydrogen vs deuterium. Measurements of the cross-phase angle between a normal-incidence reflectometer and an ECE signal were made to infer the cross-phase angle between density and temperature fluctuations. The magnitude of the cross-phase angle was found larger (more out-of-phase) in hydrogen than in deuterium. TRANSP power balance simulations show a larger ion heat flux in hydrogen where the electron-ion heat exchange term is found to play an important role. These experimental observations were used as the basis of a validation study of both quasilinear gyrofluid trapped gyro-Landau fluid-SAT2 and nonlinear gyrokinetic GENE codes. Linear solvers indicate that, at long wavelengths (k⊥ρs<1), energy transport in the deuterium discharge is dominated by a mixed ion-temperature-gradient (ITG) and trapped-electron mode turbulence while in hydrogen transport is exclusively and more strongly driven by ITG turbulence. The Ricci validation metric has been used to quantify the agreement between experiments and simulations taking into account both experimental and simulation uncertainties as well as four different observables across different levels of the primacy hierarchy.
Measurements of variable capacitance using single port radio frequency reflectometry
Authors: Celis-Cordova Rene , Gose Jacob J. , Brown Abigail F. , Behn AnnahMarie G. , Huebner Matthew , Williams Ethan M. , Xiang Yang , Chisum Jonathan D. , Orlov Alexei O. , Snider Gregory L.
Published: August 2023

A radio frequency (RF) reflectometry technique is presented to measure device capacitances using a probe station. This technique is used to characterize micro-electromechanical system (MEMS) variable capacitor devices that can be connected to create pull-up and pull-down networks used in digital gates for reversible computing. Adiabatic reversible computing is a promising approach to energy-efficient computing that can dramatically reduce heat dissipation by switching circuits at speeds below their RC time constants, introducing a trade-off between energy and speed. The variable capacitors in this study will be measured using single port RF reflectometry achieved with a custom-made RF probe. The RF probe consists of a micromanipulator with an on-board matching network and is calibrated by measuring a capacitive bank that shows a clearly visible frequency shift with the increase in capacitance. The RF probe worked well when measuring static capacitors with no parasitic resistance; however, the frequency shift is masked when measuring the MEMS variable capacitors due to their high in-series parasitic resistance (around 80 kΩ). Therefore, RF reflectometry has the potential to measure MEMS variable capacitors in the range of 0–30 fF when not masked by a high in-series parasitic resistance, creating a fast and versatile method for characterizing variable capacitors that can be used in energy-efficient computing.
Aluminum scandium nitride films for piezoelectric transduction into silicon at gigahertz frequencies
Authors: Hackett L. , Miller M. , Beaucejour R. , Nordquist C. M. , Taylor J. C. , Santillan S. , Olsson R. H. , Eichenfield M.
Published: August 2023

Recent advances in the growth of aluminum scandium nitride films on silicon suggest that this material platform could be applied for quantum electromechanical applications. Here, we model, fabricate, and characterize microwave frequency silicon phononic delay lines with transducers formed in an adjacent aluminum scandium nitride layer to evaluate aluminum scandium nitride films, at 32% scandium, on silicon interdigital transducers for piezoelectric transduction into suspended silicon membranes. We achieve an electromechanical coupling coefficient of 2.7% for the extensional symmetric-like Lamb mode supported in the suspended material stack and show how this coupling coefficient could be increased to at least 8.5%, which would further boost transduction efficiency and reduce the device footprint. The one-sided transduction efficiency, which quantifies the efficiency at which the source of microwave photons is converted to microwave phonons in the silicon membrane, is 10% at 5 GHz at room temperature and, as we discuss, there is a path to increase this toward near-unity efficiency based on a combination of modified device design and operation at cryogenic temperatures.
Plasma application in atomic layer etching
Authors: Fischer Andreas , Lill Thorsten
Published: August 2023

Atomic layer etching (ALE) has emerged as a promising technique for the precise and controlled removal of materials in nanoscale devices. ALE processes have gained significant attention due to their ability to achieve high material selectivity, etch uniformity, and atomic-scale resolution. This article provides a perspective of the important role of plasma in ALE including thermal ALE for nanometer-scale device manufacturing. Advantages as well as challenges of ALE are discussed in contrast to classic reactive ion etching. A tally-up of known plasma-based ALE processes is listed, and novel thermal ALE processes are described that are based on the so-called ligand addition mechanism. We explain the potential of using plasma for increasing wafer throughput in a manufacturing environment, its use when it comes to anisotropy tuning, the benefits in enabling a wider range of pre-cursors in thermal ALE, and the advantages it may bring for thermal ALE of crystalline materials. The benefits and challenges of different plasma sources in ALE are discussed, and an outlook for future development is provided. Finally, applications of plasma for productivity reasons such as particle avoidance and process stability are outlined.
3D-tomographic reconstruction of gliding arc plasma
Authors: Sanned David , Nilsson Sebastian , Roth Adrian , Berrocal Edouard , Ehn Andreas , Richter Mattias
Published: August 2023

This study presents three-dimensional (3D) emission tomography on gliding arc discharge for volumetric measurements of plasma luminosity fields. The 3D tomography of the plasma luminosity field enables quantification and characterization of 3D plasma features, which are not easily accessible in two-dimensional measurements. Simultaneous projections of the plasma discharge were imaged using multiple CMOS cameras, and an in-house developed tomographic method was used for the 3D reconstruction of the luminosity fields. Results show good field reconstruction quality and expected gliding arc topologies. Comparisons between arc 3D length and 2D projected length displayed that 2D measurements underestimated length by around 15% at the highest tested flow case. The mean 3D length initially increased with increasing air flow, while later decreasing at even higher flows. The standard deviation of 3D length increased with increasing flow. Arc curvature and overlap were generally seen to increase with higher flows in contrast to arc volume that was seen to decrease with increasing flow rates. This study aims to facilitate instantaneous 3D tomographic measurements of plasma luminosity fields to provide a detailed quantification of 3D characteristics and correlations of typical plasma features, thereby providing paths to remove line-of-sight effects and compensate for loss of information that may occur during two-dimensional measurements. The presented technique is applicable not only to gliding arcs but also to various other plasma systems.
Passively Q-switched Er3+-doped fiber laser based on double-transition metal MAX phase TiNbAlC saturable absorber
Authors: Zhao Bin , Zhang Hongping , Ma Rongze , Li Zhenrui , Wang Pengfei
Published: August 2023

We demonstrated a stable passively Q-switched fiber laser operation at 1531.57 nm using a double-transition metal MAX phase TiNbAlC saturable absorber. The prepared saturable absorber’s modulation depth, saturation intensity, and non-saturation loss are 1.75%, 0.089 MW/cm2, and 32.81%, respectively. Using the TiNbAlC saturable absorber within an erbium-doped fiber laser ring cavity, stable Q-switched pulses with a central wavelength of 1531.57 nm, and a 3-dB bandwidth of 1.43 nm are acquired. The minimum pulse duration and the maximum single pulse energy are 3.18 μs and 51.56 nJ, respectively. Furthermore, the maximum repetition rate is 37.9 kHz with a signal-to-noise ratio of 50 dB. Our results indicate that double-transition metal MAX phase TiNbAlC can be an excellent saturable absorber candidate for an ultrashort pulse fiber laser.
High temperature and pressure Gladstone–Dale coefficient measurements in air behind reflected shock waves
Authors: Wang Gwendolyn T. , Daniel Kyle A. , Lynch Kyle P. , Guildenbecher Daniel R. , Mazumdar Yi C.
Published: August 2023

Understanding the optical properties of air is essential for the validation and characterization of plasmas and hypersonic flows. Beyond 6000 K, the dissociation of nitrogen and oxygen molecules, along with other reactions, alters the equilibrium composition of air, causing a temperature and pressure dependence in the Gladstone–Dale coefficient. Due to measurement complexities, there is currently very little experimental data to validate model predictions under these conditions. In this work, a unique quadrature fringe imaging interferometer technique is applied to high temperature and pressure measurements of air in the Sandia free-piston high enthalpy shock tube. The diagnostic method combines a narrowband and broadband source to capture large, nearly-discrete changes in the index of refraction by calibrating to interference pattern changes. For the experiments, the reflected shock front is used to generate temperatures between 6000 and 7800 K at pressures up to 300 psi (20 bars). Results behind the shock front exhibit complex flow bifurcation and tail shock feature before equilibrium conditions are reached. Measurements in these flows show close agreement with theoretical predictions of the nonconstant Gladstone–Dale coefficient at high temperatures and high pressures, providing new validation data for chemical equilibrium gas models.
A TGF-β/KLF10 signaling axis regulates atrophy-associated genes to induce muscle wasting in pancreatic cancer
Authors: Dasgupta Aneesha , Gibbard Daniel F. , Schmitt Rebecca E. , Arneson-Wissink Paige C. , Ducharme Alexandra M. , Bruinsma Elizabeth S. , Hawse John R. , Jatoi Aminah , Doles Jason D.
Published: August 2023

Cancer cachexia, and its associated complications, represent a large and currently untreatable roadblock to effective cancer management. Many potential therapies have been proposed and tested—including appetite stimulants, targeted cytokine blockers, and nutritional supplementation—yet highly effective therapies are lacking. Innovative approaches to treating cancer cachexia are needed. Members of the Kruppel-like factor (KLF) family play wide-ranging and important roles in the development, maintenance, and metabolism of skeletal muscle. Within the KLF family, we identified KLF10 upregulation in a multitude of wasting contexts—including in pancreatic, lung, and colon cancer mouse models as well as in human patients. We subsequently interrogated loss-of-function of KLF10 as a potential strategy to mitigate cancer associated muscle wasting. In vivo studies leveraging orthotopic implantation of pancreas cancer cells into wild-type and KLF10 KO mice revealed significant preservation of lean mass and robust suppression of pro-atrophy muscle-specific ubiquitin ligases Trim63 and Fbxo32, as well as other factors implicated in atrophy, calcium signaling, and autophagy. Bioinformatics analyses identified Transforming growth factor beta (TGF-β), a known inducer of KLF10 and cachexia promoting factor, as a key upstream regulator of KLF10. We provide direct in vivo evidence that KLF10 KO mice are resistant to the atrophic effects of TGF-β. ChIP-based binding studies demonstrated direct binding to
Trim63
, a known wasting-associated atrogene. Taken together, we report a critical role for the TGF-β/KLF10 axis in the etiology of pancreatic cancer–associated muscle wasting and highlight the utility of targeting KLF10 as a strategy to prevent muscle wasting and limit cancer-associated cachexia.
Organelle-dependent polyprotein designs enable stoichiometric expression of nitrogen fixation components targeted to mitochondria
Authors: Yang Jianguo , Xiang Nan , Liu Yiheng , Guo Chenyue , Li Chenyu , Li Hui , Cai Shuyi , Dixon Ray , Wang Yi-Ping
Published: August 2023

Introducing nitrogen fixation (
nif
   ) genes into eukaryotic genomes and targeting Nif components to mitochondria or chloroplasts is a promising strategy for engineering nitrogen-fixing plants. A prerequisite for achieving nitrogen fixation in crops is stable and stoichiometric expression of each component in organelles. Previously, we designed a polyprotein-based nitrogenase system depending on Tobacco Etch Virus protease (TEVp) to release functional Nif components from five polyproteins. Although this system satisfies the demand for specific expression ratios of Nif components in
Escherichia coli
, we encountered issues with TEVp cleavage of polyproteins targeted to yeast mitochondria. To overcome this obstacle, a version of the Nif polyprotein system was constructed by replacing TEVp cleavage sites with minimal peptide sequences, identified by knowledge-based engineering, that are susceptible to cleavage by the endogenous mitochondrial-processing peptidase. This replacement not only further reduces the number of genes required, but also prevents potential precleavage of polyproteins outside the target organelle. This version of the polyprotein-based nitrogenase system achieved levels of nitrogenase activity in
E. coli
, comparable to those observed with the TEVp-based polyprotein nitrogenase system. When applied to yeast mitochondria, stable and balanced expression of Nif components was realized. This strategy has potential advantages, not only for transferring nitrogen fixation to eukaryotic cells, but also for the engineering of other metabolic pathways that require mitochondrial compartmentalization.
Highly selective NH
3
synthesis from N
2
on electron-rich Bi
0
in a pressurized electrolyzer
Authors: Wang Yongtao , Lin Xiaoyun , Zhang Gong , Gao Hui , Zhao Zhi-Jian , Zhang Peng , Wang Tuo , Gong Jinlong
Published: August 2023

Electrochemical conversion of N
2
into ammonia presents a sustainable pathway to produce hydrogen storage carrier but yet requires further advancement in electrocatalyst design and electrolyzer integration. This technology suffers from low selectivity and yield owing to the extremely strong N≡N bond and the exceptionally low solubility of N
2
in aqueous systems. A high NH
3
synthesis performance is restricted by the high activation energy of N≡N bond and the supply insufficiency of N
2
to active sites. This paper describes the introduction of electron-rich Bi
0
sites into Ag catalysts with a high-pressure electrolyzer that enables a dramatically enhanced Faradaic efficiency of 44.0% and yield of 28.43 μg cm
−2
h
−1
at 4.0 MPa. Combined with density functional theory results, in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy demonstrates that N
2
reduction reaction follows an associative mechanism, in which a high coverage of N–N bond and −NH
2
intermediates suggest electron-rich Bi
0
boosts sound activation of N
2
molecules and low hydrogenation barrier. The proposed strategy of engineering electrochemical catalysts and devices provides powerful guidelines for achieving industrial-level green ammonia production.
Regulation mechanism of porous structures on flashover performances: combined effect of hindering collision ionization and corona stabilization
Authors: Li Meng-Tao , Zhu Ming-Xiao , Luo Lu-Yang , Guo Xiao-Bo , Chen Ji-Ming
Published: August 2023

The microscopic morphology is recognized as one of the key factors affecting the surface flashover strength, but the effect of nanoscale morphology is rarely investigated. In this paper, a novel strategy, namely, porous structural material was presented to improve the flashover strength, and porous nylon membranes with pore diameter from 100 nm to 5000 nm were used to explore the influence of nano-scale porous morphology on the flashover strength. The regulation mechanism of porous structures on flashover performances were explored through the analysis of potential scanning, partial discharge measurement, corona and flashover optical photos. The results indicated that the flashover strength under both AC and DC voltages could be significantly improved by the porous morphology, with a maximum increment of higher than 100%. It is believed that the improved flashover strength is attributed to the combined effect of hindering collision ionization and corona stabilization of porous structures. The present research provides a new insight for improving the surface insulation performance.
Plasma electrochemical synthesis of silicon quantum dots
Authors: Ma Yupengxue , Wang Ruoyu , Qin Xiaoru , Zhang Qing , Zhong Xiaoxia
Published: August 2023

Environmentally friendly and fast synthesis of silicon quantum dots (SiQDs) is realized with the assistance of plasma. The precursors used are N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane (DAMO) and citric acid. When the excitation wavelength was 370 nm, the photoluminescence emission peak of the SiQDs appeared at 452.5 nm. The optimization of precursor concentration, reaction time and other parameters can effectively improve the quantum yield (QY) of SiQDs. The results show that the amidation and condensation of DAMO and citric acid plays an important role in the improvement of QY, as this means that more fluorescent molecules are produced and therefore QY is increased. This paper increases QY from 4.23% to 23.9%, providing a promising way to improve QY even more.
Unveiling orientation dependence of anisotropic plasticity in polycrystalline copper by nanoindentation
Authors: Tan Rongkai , Wang Zhanfeng , Wu Shilei , Liu Weili , Jiang Beibei
Published: August 2023

The mechanical properties of crystalline materials are influenced by their deformation behavior, which is associated with their microstructural characteristics. Specifically, crystallographic orientation greatly affects the microscale plastic deformation of individual grains. In this study, experiments and finite element simulations of Berkovich nanoindentations are conducted to investigate the impact of crystallographic orientation in polycrystalline copper. A crystal plasticity constitutive model is developed for copper materials, which accurately captures their indentation mechanical response. The results showed that the indentation behavior of polycrystalline copper exhibits a high degree of anisotropy due to significant variation in slip systems for different crystallographic orientations. This results in different mechanical responses of individual grains and distinct material pileup morphologies on the indented surface. Additionally, the study revealed that crystallographic orientation plays a critical role in determining the indentation size effect. These findings have important implications for the design of materials where plasticity is a crucial factor.
Caloric effects in liquid crystal-based soft materials
Authors: Črešnar Dejvid , Derets Nikita , Trček Maja , Skačej Gregor , Rešetič Andraž , Lavrič Marta , Domenici Valentina , Zalar Boštjan , Kralj Samo , Kutnjak Zdravko , Rožič Brigita
Published: August 2023

With the increased environmental awareness, the search for environmentally friendlier heat-management techniques has been the topic of many scientific studies. The caloric materials with large caloric effects, such as the electrocaloric (EC) and elastocaloric (eC) effects, have increased interest due to their potential to realize new solid-state refrigeration devices. Recently, caloric properties of soft materials, such as liquid crystals (LCs) and LC elastomers (LCEs), are getting more in the focus of caloric materials investigations, stimulated by large caloric effects observed in these materials. Here, an overview of recent direct measurements of large caloric effects in smectic LC 14CB and main-chain LCEs is given. Specifically, high-resolution thermometric measurements revealed a large EC response in 14CB LC exceeding 8 K. Such a large effect was obtained at a relatively moderate electric field of 30 kV cm−1 compared to solid EC materials. We demonstrate that such a small field can induce the isotropic to smectic A phase transition in 14CB, releasing or absorbing relatively large latent heat that enhances the EC response. Furthermore, it is demonstrated that in main-chain LCEs, the character of the nematic to isotropic transition can be tuned from the supercritical towards the first-order regime by decreasing the crosslinkers’ density. Such tuning results in a sharper phase transition and latent heat that enhance the eC response, exceeding 2 K and with the eC responsivity of 24 K MPa−1, about three orders of magnitude larger than the average eC responsivity found in the best shape memory alloys. Significant caloric effects in soft LC-based materials, observed at much smaller fields than in solid caloric materials, demonstrate their ability to play an important role as new cooling elements, thermal diodes, and caloric-active regeneration material in new heat-management devices.
The smallest eigenvalue of the ill-conditioned Hankel matrices associated with a semi-classical Hermite weight
Authors: Wang Yuxi , Zhu Mengkun , Chen Yang
Published: August 2023

In this paper, we study the asymptotic behavior of the smallest eigenvalue

λ
N

\lambda _N

, of the

(
N
+
1
)
×
(
N
+
1
)

(N+1)\times (N+1)

Hankel matrix

M

N

=
(

μ

j
+
k

)

0
≤
j
,
k
≤
N

\mathcal {M}_N=(\mu _{j+k})_{0\le j,k\le N}

generated by the semi-classical Hermite weight
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="w left-parenthesis z comma t right-parenthesis equals StartAbsoluteValue z EndAbsoluteValue Superscript lamda Baseline exp left-parenthesis minus z squared plus t z right-parenthesis comma z comma t element-of double-struck upper R comma lamda greater-than negative 1">

w
(
z
,
t
)
=

|

z

|

λ

exp
⁡

(
−

z
2

+
t
z
)

,
z
,
t
∈

R

,
λ
>
−
1

w(z,t)=|z|^\lambda \exp \left (-z^2+tz\right ), z, t \in \mathbb {R}, \lambda >-1

. An asymptotic expression of the orthonormal polynomials

P

N

(
z
)

\mathcal {P}_N(z)

with the semi-classical Hermite weight

w
(
z
,
t
)

w(z,t)

is established as

N
N

tends to infinity. Based on the orthonormal polynomials

P

N

(
z
)

\mathcal {P}_N(z)

, we obtain the specific asymptotic formulas of

λ

N

\lambda _{N}

.
Spacetime integral bounds for the energy-critical nonlinear wave equation
Authors: Dodson Benjamin
Published: August 2023

In this paper we prove a global spacetime bound for the quintic, nonlinear wave equation in three dimensions. This bound depends on the

L

t

∞

L

x

2

L_{t}^{\infty } L_{x}^{2}

and

L

t

∞

H
˙

2

L_{t}^{\infty } \dot {H}^{2}

norms of the solution to the quintic problem. The main motivation for this paper is the use of an interaction Morawetz estimate for the nonlinear wave equation.
The Association of Air Pollution Exposure With Glucose and Lipid Levels: The Role of an Extreme Air Pollution Event Alongside 2 Decades of Moderate Exposure
Authors: Knobel Pablo , Just Allan C , Colicino Elena , Teitelbaum Susan L , McLaughlin Mary Ann , Amini Heresh , Yitshak Sade Maayan
Published: August 2023

Extreme air pollution events and moderate exposure to fine particulate matter (PM2.5) are associated with increased cardiometabolic risk. The World Trade Center (WTC) Health Program general responder cohort includes responders to the WTC disaster. We investigated whether their exposure to this extreme air pollution event (2001) was associated with long-term metabolic outcomes, independently from the associations of intermediate-term PM2.5 exposure later in life (2004–2019). We included 22,447 cohort members with cholesterol (n = 96,155) and glucose (n = 81,599) laboratory results. Self-reported WTC exposure was derived from a questionnaire. PM2.5 exposure was derived from a satellite-based model. We observed an increase of 0.78 mg/dL (95% confidence interval (CI): 0.30, 1.26) in glucose and 0.67 mg/dL (95% CI: 1.00, 2.35) in cholesterol levels associated with an interquartile range increase in PM2.5 averaged 6 months before the study visit. Higher WTC-exposure categories were also associated with higher cholesterol (0.99 mg/dL, 95% CI: 0.30, 1.67, for intermediate exposure) and glucose (0.82 mg/dL, 95% CI: 0.22, 1.43, for high exposure) levels. Most associations were larger among people with diabetes. Extreme air pollution events and intermediate PM2.5 exposure have independent metabolic consequences. These exposures contributed to higher glucose and lipids levels among WTC responders, which may be translated into increased cardiovascular risk.
Fighting for Real: Truth and American War Memory
Authors: Vincent Jonathan
Published: August 2023

This essay-review considers two recent books on the subject of American veteran memoir—Stephen Cushman’s The General’s Civil War (2021) and Myra Mendible’s American War Stories (2021). Surveying military conflicts centered on the US Civil War and the more recent wars from Vietnam to Afghanistan, both authors examine a range of veteran nonfiction writing, and with the explicit purpose of speaking to US audiences in our own time. Given the United States’ severely divided political culture today, both authors see the lessons and hard truths expressed in veteran memoir as rife with possibilities for addressing American social divisions in the twenty-first century. Along the way, a preoccupation with the very themes of “truth” and “reality” exposed by war representation leads both authors, though for very different reasons, to meditate on the need for new epistemological frameworks that, given the limitations of a waning postmodernism, would restore a fresh commitment to both. While very different philosophies of history shape the perspectives of each author, the revivified commitment to truth-telling unites their accounts.[A] . . . central theme . . . in . . . US military history and the literary portrayal of war is the renewed commitment to historical veracity, expanded factuality, and representational depth—in short, a fuller, more capacious picture of both the truth and reality of war-making.