bluuebunny/crossref_metadata_2025 huggingface dataset:
Gluteal Region Reshaping of Massive Weight Loss Patients—A Decision-Making Strategy
Authors: Mahgoub Mohamed Ali , Zeina Ahmed Mahmoud , Bahaa El-Din Ahmed Mohamed , El-Sabbagh Ahmed Hassan , Bassetto Franco , Vindigni Vincenzo
Published: May 2022

Background Massive weight loss (MWL) is a very common presentation that you may face as a plastic surgeon. Each patient has his own individual criteria, so, you should work according to a well-organized plan, especially when such cases have concerns about their gluteal area contour that were neglected before by many surgeons. A decision-making strategy was used to give a personalized treatment for targeting gluteal region reshaping of MWL patients.

Methods This study considered all patients with MWL subjected to buttock reshaping. There was no randomization in treatment; there was a case-by-case assessment. We analyzed the features of the buttocks, the type of surgery performed, the outcomes, and the complications.

Results Fifty two patients were included (41 females and 11 males), ages ranged between 21 and 66 years. Demographic data, preoperative body mass index (BMI), duration of surgery, type of surgery, and postoperative complications were collected. Statistically significant improvements were observed in gluteal ptosis and patient satisfaction grades.

Conclusion Aesthetic improvement of the buttocks involves either augmentation or contouring that may be obtained by liposculpture, surgical lifting, or combination. Patients with MWL have high expectations and are often treated with multiple procedures. Thus, an easy strategic approach personalized on each patient to treat multiple adjacent areas in one operation is necessary. Adipose tissue distribution, gluteal skin status, and BMI were the main factors that can forcefully affect our plan to guarantee reduction of unpleasant results and complications and improve patient satisfaction.
A New Complex Minimally Invasive Thread Lift Method for One-Time Three-Step Fixation of the Face and Neck Soft Tissues
Authors: Zhukova Olga , Dydykin Sergey , Kubíková Eliska , Markova Natalia , Vasil'ev Yuriy , Kapitonova Marina
Published: May 2022

Background In recent years thread lift has become widespread; however, existing methods need to improve their long-term outcome, which requires considering topographic anatomy of face and neck, especially the ligamentous apparatus. This study aims to assess the effectiveness and safety of an innovative method of one-time three-step thread facelift, which provides an additional support to the ligamentous structures of the upper, middle, and lower thirds of the face and neck.

Methods The study included 357 patients aged 32 to 67 years with various morphotypes of aging. The original method of thread lift was applied, and its effectiveness was followed up for to 2 years. The Wrinkle Severity Rating Score (WSRS) and Global Aesthetic Improvement Scale (GAIS) scores were used for assessment by investigators, independent observers, and patients. Statistical significance was determined using paired t-test and chi-square test.

Results The mean WSRS score was 3.88 ± 0.88 before the thread lift, 1.93 ± 0.81 one month after the procedure, and 2.36 ± 0.85 after 2 years of follow-up. The mean GAIS was 4.80 ± 0.04 one month after thread lift, and 4.01 ± 0.04 after 2 years, while in the patients' assessment Global Satisfaction Scale was 4.86 ± 0.02 and 4.10 ± 0.02, respectively. There were no clinically significant complications throughout the observation period.

Conclusion The new method of one-time three-step thread fixation of the soft tissues of the face and neck demonstrated a high degree of satisfaction by both experts and patients after 2 years of follow-up. It showed high efficacy and safety, including in the group of patients with pronounced age-related changes of the skin of face and neck.
Ultrasonographic Assessment of the Cutaneous Changes Induced by Topical Use of Novel Peptides Comprising Laminin 5
Authors: Park Kyong Chan , Kim Se Young , Khan Galina , Park Eun Soo
Published: May 2022

Background Laminin 5, which is found in the basement membrane of dermal-epidermal junction (DEJ), is a major adhesive component and associated with proliferating and migrating keratinocytes. In this study, we hypothesized that the topical application of the skin care products containing the novel peptides might restore the DEJ structure by deriving deposition of laminin 5 and promoting the keratinocyte migration. Here, we evaluated the restoration of DEJ by measuring the skin thickness.

Methods Single-center retrospective analysis was performed on a total of 13 patients who underwent skin care using Baume L.C.E. (France, Laboratories d' Anjou) between January and March 2021. All patients applied the skin care agent for 2 weeks only on their left hand dorsum. Before the initiation of the application and after 2 weeks, both their hands were evaluated on photography and ultrasound. And the patients were asked to rate their satisfaction with the questionnaire after 2 weeks.

Results There was no obvious improvement in photographic assessment and questionnaire. The post–pre difference of skin thickness in ultrasound images was, in left hand, 0.1 ± 0.37 in distal point and 0.1 ± 0.35 in proximal point; and, in right hand, 0 ± 0.17 in distal point and 0 ± 0.15 in proximal point, respectively. The pre–post difference was statistically significant in proximal point (p = 0.035).

Conclusion Topical application of novel peptide derivative comprising laminin 5 demonstrated cutaneous changes including skin thickness, as assessed by ultrasound. Further studies using other modalities including dermal density measurement, three-dimensional photography, optical coherence tomography, or skin biopsy would be helpful to determine the skin-improving effects.
The Impact of Abdominal Liposuction on Abdominally Based Autologous Breast Reconstruction: A Systematic Review
Authors: Bond Evalina S. , Soteropulos Carol E. , Poore Samuel O.
Published: May 2022

Prior abdominal liposuction can be viewed as a relative or absolute contraindication to abdominally based autologous breast reconstruction given concerns for damaged perforators and scarring complicating intraoperative dissection. This systematic review aims to explore the outcomes of abdominally based breast reconstruction in patients with a history of abdominal liposuction. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-guided literature search was conducted using PubMed, Scopus, and Web of Science from the earliest available date through June 2020. Deep inferior epigastric perforator, muscle-sparing transverse rectus abdominis musculocutaneous (TRAM), superficial inferior epigastric artery, and pedicled TRAM flaps were included for evaluation. Complications included total or partial flap loss, fat necrosis, seroma, delayed wound healing, and donor site complications. After inclusion criteria were applied, 336 nonduplicate articles were screened, yielding 11 for final review, representing 55 flaps in 43 patients. There was no instance of total flap loss, eight (14.5%) flaps developed partial loss or fat necrosis, three (5.4%) flaps had delayed wound healing, and two (4.6%) patients had donor site complications. Most authors (8/11) utilized some type of preoperative imaging. Doppler ultrasonography was the most used modality, and these patients had the lowest rate of partial flap loss or flap fat necrosis (8%), followed by those without any preoperative imaging (10%). In conclusion, this review supports that patients undergoing abdominally based autologous breast reconstruction with a history of abdominal liposuction are not at an increased risk of flap or donor site complications. Although preoperative imaging was common, it did not reliably decrease complications. Further prospective studies are needed to address the role of imaging in improving outcomes.
Patient-Reported Outcomes after Subpectoral Breast Augmentation with Microtextured or Macrotextured Implants Using the BREAST-Q
Authors: Leite Alice Teixeira , Sabino-Neto Miguel , Resende Vanessa Contato Lopes , Veiga Daniela Francescato , Ferreira Lydia Masako
Published: May 2022

Background Breast augmentation with implants is the most commonly performed cosmetic plastic surgery in Brazil and worldwide. The aim of this study was to assess patient satisfaction and quality of life following subpectoral breast augmentation with either microtextured or macrotextured implants, using the BREAST-Q.

Methods A prospective study was conducted with 40 women with hypomastia undergoing subpectoral breast augmentation. The patients were randomly allocated to two groups to receive either microtextured or macrotextured breast implants. All participants were assessed preoperatively (baseline) and after 2 and 4 months of surgery for quality of life and patient satisfaction with the surgical results, using the BREAST-Q augmentation module, a patient-reported outcome measure.

Results The patients had a mean age of 28.9 ± 6.45 years. The microtextured (n = 20) and macrotextured (n = 20) groups were homogeneous for sex, age, education level, marital status, and number of children (p > 0.05). Both groups showed significant improvement in satisfaction with breasts (p < 0.001), psychosocial well-being (p < 0.001), and sexual well-being (p < 0.001) at the 2- and 4-month follow-up visits compared with baseline. The observed improvements were associated with high effect size values of 5.09, 3.44, and 3.90, respectively. In contrast, significant decreases from baseline in physical well-being scores (p = 0.001) were found 2 and 4 weeks after surgery in both groups.

Conclusion Subpectoral breast augmentation with either microtextured or macrotextured breast implants improved satisfaction with breasts and quality of life in patients with hypomastia.
Gigantomastia as a Cause of Pulmonary Hypertension
Authors: Castillo Juan Pablo , Robledo Ana María , Torres-Canchala Laura , Roa-Saldarriaga Lady
Published: May 2022

Reduction mammaplasty is the gold standard treatment for gigantomastia. We report one female patient with juvenile gigantomastia associated with severe pulmonary hypertension where her pulmonary pressure decreased significantly after the surgery, improving her quality of life. A 22-year-old female patient with gigantomastia since 10 years old, tricuspid regurgitation, and pulmonary thromboembolism antecedent was admitted to the emergency department. Her oxygen saturation was 89%. Acute heart failure management was initiated. An echocardiogram reported left ventricle ejection fraction (LVEF) of 70% with severe right heart dilation, contractile dysfunction, and arterial pulmonary pressure (PASP) of 110 mm Hg. A multidisciplinary team considered gigantomastia could generate a restrictive pattern, so a Thorek reduction mammoplasty with Wise pattern was performed. Presurgical measurements were: sternal notch to nipple-areola complex, right 59 cm, left 56 cm. Three days after surgery, the patient could breathe without oxygen support. In the outpatient follow-up, patient referred reduction of her respiratory symptoms and marked improvement in her quality of life. Six months after surgery, a control echocardiogram showed a LVEF of 62% and PASP of 85 mm Hg. Pulmonary hypertension may be present in patients with gigantomastia. Reduction mammoplasty may be a feasible alternative to improve the cardiac signs and symptoms in patients with medical refractory management.
Mucormycosis Management in COVID-19 Era: Is Immediate Surgical Debridement and Reconstruction the Answer?
Authors: Gupta Samarth , Goil Pradeep , Mohammad Arbab , Escandón Joseph M.
Published: May 2022

Background Excessive use of corticosteroids therapy along with gross immunocompromised conditions in the novel coronavirus disease 2019 (COVID-19) pandemic has raised the risks of contracting opportunistic fungal infections. Here, we describe our experience with the implementation of a surgical protocol to treat and reconstruct rhino-orbital-cerebral mucormycosis.

Methods A retrospective review of our prospectively maintained database was conducted on consecutive patients diagnosed with mucormycosis undergoing immediate reconstruction utilizing our “Mucormycosis Management Protocol.” All patients included in this study underwent reconstruction after recovering from COVID-19. Wide local excision was performed in all cases removing all suspected and edematous tissue. Reconstruction was done primarily after clear margins were achieved on clinical assessment under a cover of injectable liposomal amphotericin B.

Results Fourteen patients were included. The average age was 43.6 years and follow-up was 24.3 days. Thirteen patients had been admitted for inpatient care of COVID-19. Steroid therapy was implemented for 2 weeks in 11 patients and for 3 weeks in 3 patients. Eight patients (57.1%) had a maxillectomy and mucosal lining resection with/without skin excision, and six patients (42.8%) underwent maxillectomy and wide tissue excision (maxillectomy and partial zygomatic resection, orbital exenteration, orbital floor resection, nose debridement, or skull base debridement). Anterolateral thigh (ALT) flaps were used to cover defects in all patients. All flaps survived. No major or minor complications occurred. No recurrence of mucormycosis was noted.

Conclusion The approach presented in this study indicates that immediate reconstruction is safe and reliable in cases when appropriate tissue resection is accomplished. Further studies are required to verify the external validity of these findings.
Total Urethra and Penile Shaft Reconstruction with Combined Pedicled Anterolateral Thigh Flap and Radial Forearm Free Flap after Total Penectomy
Authors: di Summa Pietro Giovanni , Sapino Gianluca , Bauquis Olivier
Published: May 2022

Total reconstruction of the penis (TPR) represents a challenge for urologists and plastic surgeons, especially when urethral length is severely reduced. We here describe, for the first time in an oncologic scenario, a double flap phalloplasty using a pedicled anterolateral thigh (ALT) flap for penile reconstruction and a radial forearm free flap (RFFF) for complete neourethra and glans reconstruction following penile amputation. A 48-year-old patient came to our department following a total penectomy with inferior urethral derivation. The indication for a double flap phalloplasty was posed as only way to fully reconstruct the urethra on its length avoiding possible complications of single flap reconstruction using tube-into-tube technique. Both flaps healed uneventfully with no neourethral strictures or fistulas described. At 18 months follow-up, the patient was extremely satisfied with the aesthetic result and was able to void in standing position. We think that a double free tissue transfer for TPR should be considered, particularly when a urethral length > 14 cm needs to be reconstructed. While the pedicled ALT can be used to reconstruct a proper penile shaft with an easily concealed scar, the RFFF can provide adequate neourethra length with satisfactory sensory recovery at the neoglans.
Misdiagnosis of Human Herpes Virus-8-Associated Kaposi's Sarcoma as Adverse Drug Eruptions
Authors: Kim Tae Hyung , Wee Syeo Young , Jeong Hyun Gyo , Choi Hwan Jun
Published: May 2022

Kaposi's sarcoma (KS) is a cancer that causes patches of abnormal tissue to grow under the skin. It also occurs in the immunosuppressive population. KS is currently believed to be caused by infection with human herpes virus-8 (HHV-8) in non-human immunodeficiency virus patient. A 79-year-old female visited the outpatient clinic presenting with increasing number and size of palpable masses on both upper and lower extremities. She was first diagnosed as drug-erupted dermatitis and stopped her medications, but the symptoms got worse. We did partial biopsy, and KS with HHV-8 was diagnosed histopathologically. She planned to undergo further evaluations and proper treatments. This rare case suggests the need to consider a classic type of KS in the differential diagnosis of specific dermatologic symptoms such as macular, nodular, and darkish patches of upper or lower extremities in elderly patients. It is believed that this case helps to strengthen awareness of this rare disease.
Coactivity of Mast Cells and Stem Cells on Angiogenesis and Antioxidants' Potentials at Inflammation, Proliferation, and Tissue Remodeling Phases of Wound
Authors: Mousavi Mahshad , Khanifar Ahmad , Mousavi Nazanin , Anbari Khatereh , Chehelcheraghi Farzaneh
Published: May 2022

Background Reactive oxygen species cause serious damage to the physiological function of tissues. Determination of total antioxidant capacity of skin tissue is one of the determinants of damaged tissue function. Mast cells (MCs) are one of the groups of cells that are invited to the site of injury. The healing process begins with the rapid release of various types of MCs' intermediate factors at the site of injury. Bone marrow mesenchymal stem cell (BMMSC) production and secretion have been shown to regenerate the skin. The aim of this research was to evaluate the wound-healing and antioxidant effects of BMMSCs per MCs.

Methods Fifty-four albino Wistar male rats were divided into three groups: (1) nonsurgery, (2) surgery, and (3) surgery + BMMSCs. Groups 2 and 3 were operated with a 3 × 8 cm flap and in group 3, cell injections (7 × 109 cell injection at the time of surgery) were performed. After days 4, 7, and 15, percentage of the surviving tissue, histological characteristics, superoxide dismutase (SOD) activity, and amount of malondialdehyde (MDA) were measured in the groups. For results, Graph Pad Prism 8 software was used, and data were analyzed and compared by analysis of variance and Tukey test.

Results BMMSCs' application decreased the amount of MDA, increased SOD activity and survival rate of the flaps, and improved the histological characteristics.

Conclusion This study revealed the protective effects BMMSCs alongside MCs against oxidative stress on the survival of the flaps. However, for clinical use, more research is needed to determine its benefits.
Methane storage in flexible and dynamical metal–organic frameworks
Authors: Forrest Katherine A. , Verma Gaurav , Ye Yingxiang , Ren Junyu , Ma Shengqian , Pham Tony , Space Brian
Published: May 2022

Recently, there has been significant interest in methane as an abundant and cleaner burning alternative to fossil fuels. Consequently, the design of media capable of the storage of methane under practical conditions has become an area of significant interest to the scientific community. While metal−organic frameworks have seen pronounced examination for this application, flexible metal−organic framework variants have been little examined despite having tremendous promise for methane storage applications. This work provides an overview of the current state of the art regarding the investigation of these systems for the purpose of providing a baseline for future research.
Mechanical properties of nucleic acids and the non-local twistable wormlike chain model
Authors: Segers Midas , Voorspoels Aderik , Sakaue Takahiro , Carlon Enrico
Published: May 2022

Mechanical properties of nucleic acids play an important role in many biological processes that often involve physical deformations of these molecules. At sufficiently long length scales (say, above ∼20−30 base pairs), the mechanics of DNA and RNA double helices is described by a homogeneous Twistable Wormlike Chain (TWLC), a semiflexible polymer model characterized by twist and bending stiffnesses. At shorter scales, this model breaks down for two reasons: the elastic properties become sequence-dependent and the mechanical deformations at distal sites get coupled. We discuss in this paper the origin of the latter effect using the framework of a non-local Twistable Wormlike Chain (nlTWLC). We show, by comparing all-atom simulations data for DNA and RNA double helices, that the non-local couplings are of very similar nature in these two molecules: couplings between distal sites are strong for tilt and twist degrees of freedom and weak for roll. We introduce and analyze a simple double-stranded polymer model that clarifies the origin of this universal distal couplings behavior. In this model, referred to as the ladder model, a nlTWLC description emerges from the coarsening of local (atomic) degrees of freedom into angular variables that describe the twist and bending of the molecule. Different from its local counterpart, the nlTWLC is characterized by a length-scale-dependent elasticity. Our analysis predicts that nucleic acids are mechanically softer at the scale of a few base pairs and are asymptotically stiffer at longer length scales, a behavior that matches experimental data.
Commissioning and first results from the new 2 × 100 TW laser at the WIS
Authors: Kroupp E. , Tata S. , Wan Y. , Levy D. , Smartsev S. , Levine E. Y. , Seemann O. , Adelberg M. , Piliposian R. , Queller T. , Segre E. , Ta Phuoc K. , Kozlova M. , Malka V.
Published: May 2022

At the Weizmann Institute of Science, a new high-power-laser laboratory has been established that is dedicated to the fundamental aspects of laser–matter interaction in the relativistic regime and aimed at developing compact laser-plasma accelerators for delivering high-brightness beams of electrons, ions, and x rays. The HIGGINS laser system delivers two independent 100 TW beams and an additional probe beam, and this paper describes its commissioning and presents the very first results for particle and radiation beam delivery.
A comparator-based constraint handling technique for evolutionary algorithms
Authors: Takami Hikaru , Obayashi Shigeru
Published: May 2022

Constraint handling is a key task for the successful optimization of design parameters in industrial design problems. This paper proposes a comparator-based constraint handling technique, called the More Less-Violations Method (MLVM), for solving real constrained optimization problems using evolutionary algorithms. The structure of the MLVM is simple and it can easily be integrated into conventional evolutionary algorithms. In the proposed method, constraint weights represent the level of importance of each constraint, enabling evolutionary compliance prioritization. Moreover, an acceptable region formed by the constraint tolerances allows trade-offs between objectives and constraints while preserving diverse solutions and improving optimization performance. These elements enable the appropriate design of industrial optimization problems. An application of this method to problems without constraint tolerances is also proposed. The JAXA/Mazda benchmark problem, developed on a real-world constrained design optimization dataset, is used to assess the performance of the MLVM. The results indicate that the MLVM realizes encouraging optimization performance.
Shock wave and bubble pulsation characteristics in a field generated by single underwater detonation
Authors: Wang Chuan-wei , Li Ning , Huang Xiao-long , Liu Wei , Weng Chun-sheng
Published: May 2022

To promote the development and application of underwater detonation propulsion technology, we built a single underwater detonation experimental system and established the corresponding axisymmetric five-equation model to study the characteristics of the flow field generated by a single underwater detonation. The shock wave formed by the degeneration of the detonation wave in the detonation tube interacted with the water–gas interface. Moreover, the jetting of detonated gas was blocked by water, which sharply increased the gas pressure and yielded a transmitted wave entering the water and a reflected wave returning to the tube. The transmitted wave reached a peak pressure of 16.77 MPa at 1280 Hz. The extremely transient gas generated by detonation jetted into the water, forming bubbles with unique pulsation characteristics and completing the first pulsation cycle (28.4 ms) under the effects of the internal gas pressure and the inertia of water. In the contraction stage, the bubble changed into a complex linked annular bubble under the effects of gravity and a free surface. However, in the expansion stage, the bubble was less affected.
Vagus nerve stimulation promotes resolution of inflammation by a mechanism that involves Alox15 and requires the α7nAChR subunit
Authors: Caravaca April S. , Gallina Alessandro L. , Tarnawski Laura , Shavva Vladimir S. , Colas Romain A. , Dalli Jesmond , Malin Stephen G. , Hult Henrik , Arnardottir Hildur , Olofsson Peder S.
Published: May 2022

Significance

Resolution of inflammation is an active process that restores tissue homeostasis and prevents the development of chronic inflammatory diseases. The mechanisms that regulate resolution of inflammation are only partially understood. Here, we showed that activation of the vagus nerve accelerated resolution of inflammation. Electrical stimulation of the vagus nerve in vivo increased levels of select specialized proresolving mediators in inflammation. Experiments in genetic mouse models revealed that the mechanism involved 12/15-lipoxgenase (Alox15), a key enzyme for biosynthesis of the identified mediators, and required the α7-nicotinic acetylcholine receptor subunit. The findings indicate that electrical signals in the vagus nerve activate a cholinergic signal promoting Alox15-dependent lipid mediator biosynthesis and accelerating resolution of inflammation, providing additional insights into neural regulation of inflammation.
Carbon disulfide: A redox mediator for organodisulfides in redox flow batteries
Authors: Chen Qiliang , Wang Wenmin , Li Xin , Guo Wei , Fu Yongzhu
Published: May 2022

Significance

The intrinsic sluggish kinetics of organodisulfides has hindered its further application in large-scale energy storage. In this work, we propose a unique redox mediator (carbon disulfide [CS
2
]) involving reversible C-S bond formation/breakage, which accelerates the reaction kinetics of organodisulfides by reducing about one-third of the energy barrier of sulfur–sulfur bond breakage. The strategy described here supplies a perspective for enhancing the electrochemical behavior of organodisulfides and greatly facilitates the development of organodisulfides in large-scale energy storage applications.
Analysis of shot peening residual stress distribution based on dislocation configuration
Authors: Zhang XingZhen , Huang Jingxiang , Niu Zhiqiang , Zhong Yining , Zhou Wenlong , Chen Guoqing , Fu Xuesong
Published: May 2022

The distribution profile of residual stress on the surface layer of shot-peened materials is often in a hook shape. We analysed the distribution characteristics of residual stress by detecting dislocation configurations. The position of maximum compressive residual stress (MCRS) shifts inward with an increase in shot peening strength. It was found that long-term orderly dislocation pile-up groups frequently appeared in the MCRS region. The location of MCRS is not necessarily related to maximum dislocation density. At low strength, both the maximum dislocation density and the MCRS are on the surface region. At high strength, the surface region structures are composed of sub-grains and dislocation cells. The position of maximum dislocation density is between the surface region and the MCRS.
Effect of hold time on resistance spot weldability of aluminium to steel
Authors: Meng Xianming , Li Siwei , Shi Liting , Zhang Yongqiang , Chen Yajun , Zhang Sai , Wu Hao
Published: May 2022

The effects of welding hold time on weld quality of aluminium alloy to dual-phase steel resistance spot welds were studied. Results demonstrated that there existed an optimum range of hold time (350∼500 ms), within which the largest weld nugget diameter (7.6 mm), thinnest intermetallic compound (IMC) layer (1∼5 µm) and maximum tensile shear peak load (4.7 kN) were obtained. Too short hold time led to shrinkage, small weld nugget and thick IMC layer due to reduced heat dissipation after removing electrodes, thus resulting in low tensile peak load and brittle fracture along the IMC layer. While too long hold time, i.e. 750 ms, produced a smaller weld nugget diameter due to more rapid heat dissipation.
Effect of ferrofluid magnetization on transformer temperature rise
Authors: Rajňák Michal , Franko Marek , Paulovičová Katarína , Karpets Maksym , Parekh Kinnari , Upadhyay Ramesh , Kurimský Juraj , Dolník Bystrík , Cimbala Roman , Havran Peter , Timko Milan , Kopčanský Peter
Published: May 2022

In electrical engineering, the heat transfer can be enhanced by changing the thermophysical properties of insulating oils. In this paper, a single-phase power transformer with a nominal power of 5 kVA is subjected to a temperature rise test with three different transformer liquids. The first test is carried out with a novel gas-to-liquid transformer oil applied as a cooling and insulating medium. The other tests are conducted with ferrofluids based on this oil and MnZn ferrite nanoparticles of a low and a high nanoparticle concentration. The ferrofluids are characterized by magnetization curves, magnetic susceptibility and temperature-dependent magnetization measurements. The nanoparticle size distribution is determined from dynamic light scattering and the magnetization data. From the temperature rise profiles of the transformer at various inner locations, it has been found that the low-concentrated ferrofluid significantly reduces the transformer temperature rise. The enhanced cooling performance is ascribed to the thermomagnetic and natural convection, and increased thermal conductivity. The application of the ferrofluid with the high nanoparticle concentration resulted in a remarkable increase of the transformer temperature rise. The deteriorative cooling effect is attributed to the hindered natural and thermomagnetic convection due to the high ferrofluid magnetization and strong magnetic interaction of the ferrofluid with the magnetic field near the transformer core.
Short-time dynamics in active systems: the Vicsek model
Authors: Rubio Puzzo M Leticia , Loscar Ernesto S , De Virgiliis Andrés , Grigera Tomás S
Published: May 2022

We study the short-time dynamics (STD) of the Vicsek model (VM) with vector noise. The study of STD has proved to be very useful in the determination of the critical point, critical exponents and spinodal points in equilibrium phase transitions. Here we aim is to test its applicability in active systems. We find that, despite the essential non-equilibrium characteristics of the VM (absence of detailed balance, activity), the STD presents qualitatively the same phenomenology as in equilibrium systems. From the STD one can distinguish whether the transition is continuous or discontinuous (which we have checked also computing the Binder cumulant). When the transition is continuous, one can determine the critical point and the critical exponents.
Edge magnetization and thermally induced spin current in nanostructured graphene
Authors: Phung Thu Thi , Nguyen Mai Thi , Pham Lien Thi , Ngo Lan Thi , Nguyen Tung Thanh
Published: May 2022

In this work, the magnetic states and thermally induced spin currents in graphene nanoflake sizes with different sizes and shapes have been investigated using Hubbard model combined with non-equilibrium Green’s function method. In addition to the antiferromagnetic (AFM) state governed by the sizes, shapes, armchair bond densities, and Coulomb energy, our calculations have also pointed out the emergence of ferromagnetic (FM) and complex magnetic states when the gate voltage is invoked in the graphene nanoflakes. More prominently, by exploiting the geometric symmetry of the nanoflakes without external fields, a pure spin current and zero charge current are generated in spin caloritronic device when the graphene nanoflakes are both in the AFM and FM states. The formation of pure spin currents driven by temperature difference depends on the graphene nanoflakes’ size, shape, temperature and gate voltage as well. The study also shows the outstanding advantages of diamond-shaped graphene nanoflakes in both magnetic properties and spin currents. This result paves the way for the possibility of practical applications of graphene materials in spintronics and spin caloritronics.
Evidence of phase stability, topological phonon and temperature-induced topological phase transition in rocksalt SnS and SnSe
Authors: Sihi Antik , Pandey Sudhir K
Published: May 2022

Both SnS and SnSe have been experimentally and theoretically confirmed as topological crystalline insulators in native rocksalt structure. Here, phononic structure, thermodynamic properties and temperature dependent electron–phonon interaction (EPI) have investigated for both the materials in rocksalt phase. Previously performed theoretical studies have predicted the phase instability of SnS in this crystal structure at ambient condition. But, after a detailed study performing on the phonon calculation of SnS, we have predicted the phase stability of SnS with considering the Sn 4p orbitals as valence states in ab-initio calculation. The importance of long range Coulomb forces along with the themodynamical properties are also described in detailed for both materials. The computed value of Debye temperature (

Θ

D

) for SnS (SnSe) is ∼315.0 K (∼201.7 K). The preliminary evidence of topological phonon is found along X–W direction, where the linear band touching is observed as compared to type II Weyl phononic material ZnSe (Liu et al 2021 Phys. Rev. B 103 094306). The topological phase transition is seen for these materials due to EPI, where non-linear temperature dependent bandgap is estimated. The predicted value of transition temperature for SnS (SnSe) is found to be ∼700 K, where after this temperature the non-trivial to trivial topological phase is seen. The strength of EPI shows more stronger impact on the electronic structure of SnS than SnSe material. The reason of non-linear behaviour of bandgap with rise in temperature is discussed with the help of temperature dependent linewidths and lineshifts of conduction band and valence band due to EPI. The present study reveals the phase stability of SnS along with the comparative study of thermal effect on EPI of SnS and SnSe. Further, the possibility of temperature induced topological phase transition provides one of important behaviour to apply these two materials for device making application.
A laser-induced breakdown spectroscopy method to assess the stochasticity of plasma-flame transition in sprays
Authors: de Oliveira Pedro M , Sitte Michael Philip , Kotzagianni Maria , M Allison Patton , Mastorakos Epaminondas
Published: May 2022

An experimental approach is presented to evaluate the impact of plasma composition arising from pulse-to-pulse energy and mixture fluctuations on the non-resonant laser-induced ignition of sprays. This allows for spark events to be conditioned on the successful or failed establishment of a flame kernel, a phase dominated by plasma decomposition and recombination reactions and the on-set of combustion reactions, that is, independent of the subsequent flame growth phase controlled by propagation phenomena only, such as fuel availability and turbulent strain. For that, laser-induced breakdown spectroscopy of the spark-generated plasma is carried out, followed by OH

∗

high-speed imaging of the kernel. Exploratory experiments in spatially uniform and polydisperse kerosene droplet distributions in a jet suggest that the hydrogen concentration in the plasma deriving from the fuel dissociated by the spark is closely related to the generated OH

∗

radicals levels and, in turn, with the success of establishing a flame kernel. This suggests that the ignition process is heavily controlled by mixture fluctuations at the spark, inherent of spray flows. The instantaneous mixture at the spark is estimated with a stochastic model, with the probability density function of the equivalence ratio exhibiting values higher than twice the mean value, while the highest probability occurs at lean conditions between the gaseous equivalence ratio and the overall equivalence ratio. The findings corroborate insights on the early-phase ignition obtained from direct numerical simulations, and the framework paves the way for the development of smart online engine-health tools to assess relight capability in future aeroengines.
Fragmented graphene synthesized on a dielectric substrate for THz applications
Authors: Rehman Hamza , Golubewa Lena , Basharin Alexey , Urbanovic Andzej , Lahderanta Erkki , Soboleva Ekaterina , Matulaitiene Ieva , Jankunec Marija , Svirko Yuri , Kuzhir Polina
Published: May 2022

Fragmented multi-layered graphene films were directly synthesized via chemical vapor deposition (CVD) on dielectric substrates with a pre-deposited copper catalyst. We demonstrate that the thickness of the sacrificial copper film, process temperature, and growth time essentially influence the integrity, quality, and disorder of the synthesized graphene. Atomic force microscopy and Kelvin probe force microscopy measurements revealed the presence of nano-agglomerates and charge puddles. The potential gradients measured over the sample surface confirmed that the deposited graphene film possessed a multilayered structure, which was modelled as an ensemble of randomly oriented conductive prolate ellipsoids. THz time domain spectroscopy measurements gave the ac conductivity of the graphene flakes and homogenized graphitic films as being around 1200 S cm−1 and 1000 S cm−1, respectively. Our approach offers a scalable fabrication of graphene structures composed of graphene flakes, which have effective conductivity sufficient for a wide variety of THz applications.
Improving coronary ultrafast Doppler angiography using fractional moving blood volume and motion-adaptive ensemble length
Authors: Zhang N , Nguyen M B , Mertens L , Barron D J , Villemain O , Baranger J
Published: May 2022

Coronary microperfusion assessment is a key parameter for understanding cardiac function. Currently, coronary ultrafast Doppler angiography is the only non-invasive clinical imaging technique able to assess coronary microcirculation quantitatively in humans. In this study, we propose to use fractional moving blood volume (FMBV), proportional to the red blood cell concentration, as a metric for perfusion. FMBV compares the power Doppler in a region of interest (ROI) inside the myocardium to the power Doppler of a reference area in the heart chamber, fully filled with blood. This normalization gives then relative values of the ROI blood filling. However, due to the impact of ultrasound attenuation and elevation focus on power Doppler values, the reference area and the ROI need to be at the same depth to allow this normalization. This condition is rarely satisfied in vivo due to the cardiac anatomy. Hereby, we propose to locally compensate the attenuation between the ROI and the reference, by measuring the attenuation law on a phantom. We quantified the efficiency of this approach by comparing FMBV with and without compensation on a flow phantom. Compensated FMBV was able to estimate the ground-truth FMBV with less than 5% variation. This method was then adapted to the in vivo case of myocardial perfusion imaging during heart surgery on human neonates. The translation from in vitro to in vivo required an additional clutter filtering step to ensure that blood signals could be correctly identified in the fast-moving myocardium. We applied the singular value decomposition filter on temporal sliding windows whose lengths were a function of myocardium motion. This motion-adaptive temporal sliding window approach was able to improve blood and tissue separation in terms of contrast-to-noise ratio, as compared to well-established constant-length sliding window approaches. Therefore, compensated FMBV and singular value decomposition assisted with motion-adaptive temporal sliding windows improves the quantification of blood volume in coronary ultrafast Doppler angiography.
Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5
Authors: Sadr Mohsen , Mishchenko Alexey , Hayward-Schneider Thomas , Koenies Axel , Bottino Alberto , Biancalani Alessandro , Donnel Peter , Lanti Emmanuel , Villard Laurent
Published: May 2022

The excitation of toroidicity-induced Alfvén eigenmodes (TAEs) using prescribed external electromagnetic perturbations (hereafter ‘antenna’) acting on a confined toroidal plasma, as well as its nonlinear couplings to other modes in the system, is studied. The antenna is described by an electrostatic potential resembling the target TAE mode structure along with its corresponding parallel electromagnetic potential computed from Ohm’s law. Numerically stable long-time linear simulations are achieved by integrating the antenna within the framework of a mixed representation and pullback scheme (Mishchenko et al 2019 Comput. Phys. Commun.
238 194). By decomposing the plasma electromagnetic potential into symplectic and Hamiltonian parts and using Ohm’s law, the destabilizing contribution of the potential gradient parallel to the magnetic field is cancelled in the equations of motion. Besides evaluating the frequencies and the growth/damping rates of excited modes compared to referenced TAEs, we study the interaction of antenna-driven modes with fast particles and indicate their margins of instability. Furthermore, we show the first nonlinear simulations in the presence of a TAE-like antenna exciting other TAE modes, as well as global Alfvén eigenmodes with different toroidal wave numbers from that of the antenna.
Relativistic high-order harmonic generation by a femto-second radially polarized laser pulse irradiating a ring plasma grating
Authors: Zhang S J , Zhuo H B , Yin Y , Zou D B , Zhao N , Zhou W M
Published: May 2022

A novel scheme for generating relativistic high-order harmonics by a relativistic radially polarized laser interacting with a plasma annular grating is proposed. The particle-in-cell results show that the radial laser field can drive the relativistic electron bunches to oscillate radially in all azimuth directions, resulting in the emission of strong harmonics. Firstly, the interference of the laser field on the plasma grating structure significantly enhances the radiated harmonics which match the phase conditions. Secondly, due to the common ring symmetry of the grating structure and laser polarization, the transverse distribution of harmonics presents a Bessel form, and there is a sharp bright spot in the center with relativistic intensity. Such high-intensity short-wave structured harmonics have broad applications in areas such as plasma diagnostics, high resolution imaging and detection.
Laser-generated supersonic plasma jets and shocks in a transverse magnetic field
Authors: Bohlin H , Brack F-E , Cervenak M , Chodukowski T , Cikhardt J , Dostál J , Dudžák R , Hubner J , Huo W , Jelinek S , Klír D , Kroll F , Krupka M , Krůs M , Pisarczyk T , Rusiniak Z , Schramm U , Nguyen-Bui T-H , Weber S , Zaraś-Szydłowska A , Zeil K , Kumar D , Schlegel T , Tikhonchuk V
Published: May 2022

The influence of a transverse magnetic field on the formation and evolution of supersonic plasma jets and shocks was studied experimentally, and compared with 3D numerical simulations. An improved jet collimation was seen due to the change in the magnetic field topology restricting the radial expansion of the ablated plasma. The magnetic field was also shown to strongly affect the shock structures, both indirectly through the modified jet geometry, as well as due to a compression of the field lines in the shock region. The interaction characteristics were found to depend on the relative contribution of the magnetic and plasma pressure in balancing the ram pressure of the jet.
Experimental investigations of plasma dynamics in the hysteresis regime of reactive RF sputter processes
Authors: Roggendorf J , Berger B , Eremin D , Oberberg M , Engel D , Wölfel C , Zhang Quan-Zhi , Awakowicz P , Lunze J , Schulze J
Published: May 2022

Reactive radio frequency (RF) sputter processes are highly relevant for thin film deposition, but there is no complete understanding of the fundamentals of their operation. While the Berg model describes the hysteresis regime considering the oxygen coverage of the boundary surfaces, a complete fundamental understanding of the plasma–surface interactions and their effects on the discharge is still missing. In this work, we provide such fundamental insights based on an extensive experimental analysis of the physics in the hysteresis regime of magnetized reactive sputter processes, where the same reactive gas admixture can lead to different discharge characteristics depending on the previous state of the plasma. A variety of plasma and surface diagnostics is used to reveal these insights. A low pressure capacitively coupled RF discharge (CCP, 13.56 MHz) with a magnetron-like magnetic field topology adjacent to the target is operated in argon gas with a variable admixture of O2. The applied RF power, the gas flows/pumping speed, as well as the neutral gas pressure are changed systematically to understand the effects of these external control parameters on the hysteresis regime. The magnetic asymmetry effect is found to play an important role, since an axially non-uniform magnetic field is used to realize a local electron confinement at the target. Similar to process control in applications, the DC self-bias is measured to stabilize the surface composition using a feedback controller with the oxygen gas flow as the manipulated variable.
Electron impact studies on the imidogen (NH+) molecular ion
Authors: Ghosh R , Chakrabarti K , Choudhury B S
Published: May 2022

Low energy electron collision calculations have been performed on the imidogen molecular ion NH+ at its equilibrium geometry using the R-matrix method. A suitable model is first built to represent the NH+ target ion. With this target model we have performed scattering calculations to obtain cross sections for electronic excitation from the X2Π ground state of NH+ to few of its excited states. The excitation cross sections are then used to approximately obtain the cross section for dissociation for the production of N+ ions. We also report the cross sections for rotational excitation of NH+ in its ground state within the Coulomb–Born approximation.
A flexure hinged piezoelectric stick–slip actuator with high velocity and linearity for long-stroke nano-positioning
Authors: Qiao Guangda , Ning Peng , Gao Qi , Yu Yang , Lu Xiaohui , Yang Shitong , Cheng Tinghai
Published: May 2022

It is difficult to simultaneously achieve high linearity, high velocity, and high resolution for long-stroke piezoelectric actuators due to their discontinuity. To improve the velocity and linearity, a linear piezoelectric stick–slip actuator is proposed inspired by the fast response characteristics of piezoelectrics, which can achieve dynamic adjustment of the normal pressure by the design of flexure hinge structure. Additionally, a new dynamic model of piezoelectric stick–slip is proposed, and the step characteristics of the backward motion to displacement surge are simulated by the proposed model. The dynamic adjustment of the normal pressure can be increased by adding the inertia block to the end of the driving arm. Compared with the performance of the actuator without an inertia block, the velocity is increased, the backward motion is suppressed, and the linearity is improved. Moreover, the linear fitting correlation coefficients R
2 of displacement curve is used to evaluate the linearity of the actuator, which can reach 0.9999 at both low (10 Hz) and high (1300 Hz) frequencies, the maximum velocity is 101.76 mm s−1, the stroke is 75 mm, and the resolution is 25 nm.