bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti-inflammatory Potential of Macamides Isolated from Yellow Tubers
of Mashua (Tropaeolum Tuberosum)
Authors: Ticona Luis Apaza , Coballes María Rodríguez , Potente Giulia , Sánchez Ángel Rumbero
Published: May 2020

Although Tropaeolum tuberosum tubers have been consumed cooked as a folk
remedy for the treatment of skin, lungs, liver and kidneys diseases, these uses
have very limited scientific basis. Therefore, this article develops a
phytochemical analysis of the yellow tubers of T. tuberosum with the
objective to assess whether the isolated compounds have anti-inflammatory
potential in the CCD-1109Sk, MRC-5 and RWPE-1 cell lines. We performed an
extraction of T. tuberosum tubers using different organic solvents,
followed by a bioguided chromatographic separation. Four macamides were
identified by LC/MS techniques, but only N-benzyllinoleamide
(1) and N-benzyloleamide (2) were isolated and
elucidated by NMR/MS techniques, given that they were present in a
larger proportion in the tubers. The anti-inflammatory potential of macamides
was evaluated by the inhibition of NF-κB and STAT3 activation. Both
compounds displayed inhibition of NF-κB activation with IC50
values of 2.28±0.54 µM;
3.66±0.34 µM and
4.48±0.29 µM for compound (1) and
6.50±0.75 µM;
7.74±0.19 µM and
8.37 ±0.09 µM for compound (2)
in CCD-1109Sk, MRC-5 and RWPE-1 cell lines, respectively. Moreover, both
compounds inhibited the STAT3 activation with IC50 of
0.61±0.76 µM;
1.24±0.05 µM and
2.10±0.12 µM for compound (1) and
5.49±0.31 µM;
7.73 ±0.94 µM and
7.79±0.30 µM for compound (2).
Therefore, isolated macamides of T. tuberosum tubers showed promising
anti-inflammatory effects, suggesting a possible beneficial use to combat
inflammatory processes of skin, lung and prostate.
Abdominal Radiograph
Authors: Raut Abhijit A. , Naphade Prashant S. , Maheshwari Sharad
Published: May 2020

Abdominal radiograph (AR) is often the initial radiological investigation performed while investigating abdominal pain even today. However, in the era of cross-sectional imaging, the role of AR in the diagnosis of acute pain abdomen is being questioned. When AR is used as a screening modality, the diagnostic yield is low. When performed in suspected cases of bowel obstruction or perforation, urinary calculi, or bowel ischemia, AR is often helpful. AR is often the first radiological investigation performed in acute abdomen. Although the role of plain radiograph is limited in the era of cross-sectional imaging, systemic approach and vigilant search for the radiological features on AR may be diagnostic and decide further line of investigation. Various gas patterns of intraluminal and free peritoneal air are helpful in localizing pathology. Different patterns of calcification seen in abdomen, ingested or inserted foreign bodies, and location of medical devices give a clue to diagnosis.
ENTEROCOCCUS FAECALIS CAUSE FOR PERSISTING INFECTION A CONFOCAL ANALYSIS
Authors: Halkai Rahul , Hegde Mithra N. , Halkai Kiran
Published: May 2020

Aim: to know ability of Enterococcus faecalis invasion into root dentin.

Methodology: Forty single rooted human intact teeth were selected, after access opening and canal debridement, all the samples were subjected for gamma sterilization to ensure complete absence of microorganisms, then exposed to Enterococcus faecalis broth, broth is placed with the help of micro pipette into root canal and also at the same time apical 1/3 of tooth were immersed into broth for 8 weeks, biomechanical preparation, obturation and coronal sealing done using GIC followed by examination under confocal laser scanning microscope after splitting the teeth samples into two halfs buccolingually.

Results: This study shows invasion of Enterococcus faecalis upto 160 μm deep in to root dentin.

Conclusion: penetration and survival of Enterococcus faecalis deep into dentin in extreme conditions may be the possible reason for persisting infection after root canal treatment.
PREVALENCE OF MENTAL RETARDATION AMONG CHILDREN IN MANGALORE
Authors: B. Bhagya , A. Ramakrishna
Published: May 2020

Objectives: This study determines the prevalence of mental retardation among school going children in Mangalore by sex, age, religion, and location. Distribution of severity of mental retardation and its relationship with age of diagnosis is reported.

Materials and methods: The prevalence was obtained from the Inclusive Education Resource Centre reports of 2011. Sex, age, religion and living area were evaluated for each child. Parents of the mentally retarded children were interviewed to record the age of diagnosis. Intelligence Quotient was assessed using Binet Kamat Test, Seguin Form Board and Vineland Social Maturity Scale.

Results: The prevalence of mental retardation was 561 of the total disabilities recorded.

The prevalence of MR was higher among males than in females (p<0.001). No notable sex difference between rural and urban areas was seen. Prevalence was higher among Hindus and between 9 to 12 years of the age group. Most of them had mild MR (48.15%). Severe and Profound MR were diagnosed at a much earlier age group than in mild and moderate types.

Conclusion: This study provides an insight to the school going children with mental retardation. Further research on study of causes for MR is needed for service planning.
SEVERITY OF MOBILE PHONE AND INTERNET USE AMONG B.SC. NURSING STUDENTS
Authors: Kumari Arpita , D'souza Melita Shiny , Dhar Thiangmon , Alex Soumya ,   Savitha
Published: May 2020

Introduction: India continues to be one of the fastest growing major telecom markets in the world. Around 60 million of internet users are from India and 19 to 40 years age group section 85% using internet in India. Young nurses today have wide spread and inexpensive access to the internet.

Aims and Objectives: To assess the severity score of mobile phone use and internet use among BSc. Nursing students and to find the relationship between mobile phone and internet use.

Study design: descriptive survey.

Methods and materials: The study was conducted among 114 BSc. nursing students in Manipal College of nursing Manipal. A convenient sampling technique was used. The data was obtained by using a demographic proforma, mobile phone addiction test and internet addiction test.

Results: Most of the subjects 50 (43.9%) belongs to 19-20 years of age. 1.8% subjects reported of having mild addiction to mobile phone use. Three (2.6%) subjects had moderate internet addiction and 35 (30.7%) subjects reported of having mild internet addiction. The 'r' value (r=0.610, p=≤0.001) showed that there is a positive relationship between use of mobile phone and internet use.
ALKALINE PHOSPHATASE – A DIAGNOSTIC MARKER OF PERIODONTITIS IN POSTMENOPAUSAL WOMEN – A. B. OCHEMICAL STUDY
Authors: Ramesh Amitha , Bhandary Rahul , Thomas Biju , D'Souza Sheehan R. , Kumari Suchetha
Published: May 2020

Background and objective: Periodontal disease is one of the common inflammatory diseases with complex etiology and is multifactorial in origin.Several enzymes are evaluated for the early diagnosis of periodontal disease. The enzyme ALP plays a role in bone metabolism. In the periodontium, ALP is very important enzyme as it is part of normal turnover of periodontal ligament, root cementum, and bone homeostasis. The deficiency of estrogen in women at menopause is contributing factor to osteoporosis and considered one of the risk factors for periodontal disease. It has been hypothesized that osteoporosis decreases alveolar bone density and in turn increases its susceptibility to resorption due to periodontal inflammation. Accelerated bone loss in menopause is related to increased bone turnover. This is accompanied by increased levels of biochemical markers such as Alkaline Phosphatase. Alteration in salivary Alkaline Phosphatase levels might be expected as an indication of periodontal disease activity.

Methods: The study included 40 subjects, 20 in each group in the age group of 50-60 years. Group 1 comprised of 20 Postmenopausal women without chronic periodontitis. Group 2 comprised of 20 Postmenopausal women with chronic periodontitis. Each saliva sample was estimated for ALP levels.

Results: The present study showed significant increase in Alkaline Phosphatase in postmenopausal women with periodontitis (Group 2) with p value <0.0001.

Interpretation and conclusion: Alkaline phosphatase can be used as a diagnostic marker of Periodontitis in postmenopausal women. However ALP cannot be solely responsible for Periodontitis but it can be used as a additional aid in diagnosing Periodontitis.
EFFECTIVENESS OF CARDIOTOCOGRAPHY TRAINING PROGRAMME ON KNOWLEDGE AND SKILL AMONG NURSES WORKING IN MATERNITY UNITS
Authors: N. Sowmya M. , Priya Gayathri , C. Ramesh , K. Jothi
Published: May 2020

The study was conducted to assess the effectiveness of Cardiotocography Training Programme on knowledge and skill among nurses working in the maternity units. An evaluative approach of pre experimental one group pretest – posttest research design was used. The present study was conducted in Sri Ramachandra Hospital, Chennai, India among 30 nurses working in the maternity units who satisfied the inclusion criteria. The samples were selected using convenient sampling technique. Cardiotocography Training Programme (CTP) th was given after assessing the level of knowledge and skill in cardiotocography by pretest, followed by posttest on 7 day. The collected data were analyzed using descriptive and inferential statistics. A significant difference was found between pretest and posttest in level of knowledge and skill (P<0.001). The study findings showed that Cardiotocography Training Programme (CTP) were effective in increasing the knowledge and skill among nurses. There was no association found between level of knowledge and skill with demographic variables.
EFFECTIVENESS OF JASMINE OIL MASSAGE ON REDUCTION OF LABOR PAIN AMONG PRIMIGRAVIDA MOTHERS
Authors: Joseph Reeja Mariam , Fernandes Philomena
Published: May 2020

The study was conducted to assess the effectiveness of jasmine oil massage on labour pain during first stage of labour among 40 primigravida women. The study design adopted was true experimental approach with pre-test - post-test control group design. The demographic Proforma were collected from the women by interview and Visual analogue scale was used to measure the level of labour pain in both the groups. Data obtained in these areas were analysed by descriptive and inferential statistics. A significant difference was found in the experimental group(tcal 9.869, p<0.05). A significant difference was found between experimental group and control group. cal The pre-test ('tcal' 0.36, p>0.05) and the post-test (tcal 11.75, p<0.05). No significant association was found between the level of labour cal cal pain and demographic variables in the experimental group. In this study Jasmine oil massage proved to reduce first stage labour pain.
UNDESCENDED CAECUM AND APPENDIX WITH RIGHT SIDED SIGMOID COLON - A CASE REPORT
Authors: Jacob Meera , H. Shivarama C. , S. Bindu , Nallathamby Rani , R. Avadhani
Published: May 2020

During routine dissection of abdomen for undergraduate students in Yenepoya Medical College, a male cadaver presented with variation in disposition of large intestine and inferior mesenteric artery. Caecum and appendix were present in the right lumbar region. The descending colon crossed the median plane in front of great vessels to the right side and then it continued as sigmoid colon in the right iliac fossa. Inferior mesenteric artery arose from right side of abdominal aorta to supply the left one third of ascending colon, descending colon and sigmoid colon.
RENAL CELL CARCINOMA WITH OSSEOUS METAPLASIA OCCURRING IN A CONTRACTED KIDNEY - A RARE CASE REPORT
Authors: Permi Harish S.
Published: May 2020

Osseous metaplasia is a rare histologic feature associated with renal cell carcinoma, occurring in a contracted kidney is still rarer. Metaplastic bone formation within the renal tumor gives an appearance similar to that of calcification. It is difficult to distinguish between bone formation and calcification on the basis of radiological imaging alone. Prognostic significance of metaplastic bone formation in renal cell carcinoma is not clear, however some report suggest good prognosis as a result of limitation of tumor spread by bone formation. This case report highlights the occurrence of renal cell carcinoma with osseous metaplasia in a contracted kidney.
Sulfite-Promoted C–H Fluoroalkyl Sulfuration of Imidazoheterocycles with Bromofluoroacetate and Elemental Sulfur
Authors: Cui Zi-Ning , Tang Ri-Yuan , Gao Yong-Chao , Huang Zi-Hao , Zhang Zhao-Sheng , Xie Jin-Xin
Published: May 2020

A transition-metal-free sulfite-promoted three-component C–H sulfuration between imidazoheterocycles, elemental sulfur, and bromofluoroacetate is developed. Sulfites, including Na2S2O4, NaHSO3, and Na2S2O3, are able to promote the formation of two C–S bonds in one step using elemental sulfur as a green sulfurating agent, allowing the rapid introduction of the synthetically useful S-fluoroacetate group into imidazoheterocycles. These new imidazoheterocycle derivatives bearing an S-fluoroacetate group can be easily modified to produce pharmaceutically attractive compounds.
Hereditary Tyrosinemia Type 1—A Rare Disease with Typical Radiological Features: Case Report and Review of Literature
Authors: Singh Somesh , Mall Rana Vishwadeep , Chaturvedi Pragya , Yadav Rajnikant R.
Published: May 2020

Hereditary tyrosinemia type 1 is one of the many inborn errors of metabolism associated with tyrosine catabolism. It is a rare disease with its incidence or prevalence in India unknown. The cascading alternate metabolism results in characteristic injury patterns to the liver, kidneys, and the central nervous system, with resultant classical radiological findings. Identifying this constellation of imaging features by a radiologist may help in arriving at a diagnosis and help referring physicians in performing appropriate biochemical tests and instituting early treatment. These usually present with chronic liver failure and are extensively evaluated for other causes of liver failure. We present a case type 1 hereditary tyrosinemia with characteristic radiological features and highlight its pathophysiology to understand the basis of these imaging findings.
The Role of the Posterolateral Tibial Slope in the Rotational Instability of the Knee in Patients Affected by a Complete Isolated Anterior Cruciate Ligament Injury: Its Value in the Decision-Making Process during the Anterolateral Ligament Reconstruction
Authors: Bargagliotti Marco , Benazzo Francesco , Bellemans Johan , Truijen Jan , Pietrobono Luigi , Formagnana Mario , Zero Enrico , Zanon Giacomo
Published: May 2020

Purpose The aim of this retrospective, multicenter study was to investigate the correlation between a high degree of rotatory instability, posterolateral tibial slope (PLTS), and anterolateral ligament (ALL) injury.

Methods The study population consisted of 76 adults with isolated, complete noncontact anterior cruciate ligament (ACL) tear. The sample was divided into two groups according to the preoperative degree of rotator instability (group A: pivot-shift test grades 2 and 3; group B: pivot-shift test grade 1). Preoperative magnetic resonance imaging (MRI) assessment included angle of PLTS, posterior shift of the lateral femoral condyle (16 mm) on the tibial plateau, and the presence/absence of ALL injury. The two groups were compared for differences.

Results There was a statistically significant association between pivot-shift test grades 2 and 3 (group A), PLTS slope angle > 9 degrees, and ALL injury (p < 0.05). Group A also demonstrated a greater posterior shift of lateral femoral condyle (>11 mm), which was, however, not statistically significant when evaluated as an isolated variable.

Conclusion Our study indicates that an increased PLTS is associated with an increased incidence of ALL injury and an increased grade of pivot shift in patients with ACL tear. Assessment of posterolateral tibial slope on MRI can therefore play a key adjunct role in the surgical planning of ALL reconstruction, especially in cases when ALL damage is radiologically difficult to detect or doubtful.

Level of Evidence This is a retrospective comparative level III study.
Improving Discourse following Traumatic Brain Injury: A Tale of Two Treatments
Authors: Henderson Amy , Roeschlein Mackenzie A. , Wright Heather Harris
Published: May 2020

Persons with traumatic brain injury (TBI) often present with discourse-level deficits that affect functional communication. These deficits are not thought to be primarily linguistic in nature but instead are thought to arise from the interaction of linguistic and cognitive processes. Discourse processing treatment (DPT) is a discourse-based treatment protocol which targets discourse deficits frequently seen in TBI. Attention Process Training-2 (APT-2) is a published treatment protocol which targets four levels of attention. The purpose of this article is to investigate the effectiveness of DPT and APT-2 in improving discourse production and cognition in adults with TBI. Our results suggest that DPT results in greater improvement in discourse informativeness and coherence, but the combination of DPT and APT-2 resulted in greater generalization to untrained stimuli. Both DPT and APT-2 appear to have some potential to improve cognition, but there was intersubject variability with regard to which treatment is more effective.
Structural and optical properties of nonpolar m- and a-plane GaN/AlGaN heterostructures for narrow-linewidth mid-infrared intersubband transitions
Authors: Monavarian Morteza , Xu Jiaming , Fireman Micha N. , Nookala Nishant , Wu Feng , Bonef Bastien , Qwah Kai S. , Young Erin C. , Belkin Mikhail A. , Speck James S.
Published: May 2020

Mid-infrared intersubband transitions are investigated in nonpolar m-plane and a-plane GaN/AlGaN multi-quantum well heterostructures. Nominally identical heterostructures were grown by ammonia molecular-beam epitaxy on free-standing m-plane and a-plane GaN substrates. A total of 12 well- and barrier-doped samples with intersubband transition energies in the range of 220–320 meV (wavelength range 3.8–5.6 μm) were grown. The intersubband absorption lines of the m-plane samples were 10–40% narrower than those of the a-plane samples, and a very narrow intersubband absorption linewidth of 38 meV (full width at half maximum) at a transition energy of approximately 250 meV (5 μm wavelength) was observed in an m-plane sample. Narrower intersubband absorption linewidths of m-plane samples can be explained by more abrupt heterostructure interfaces revealed by structural characterization, which is attributed to a higher stability of the m-plane compared to the a-plane. No significant difference in the intersubband absorption linewidth was observed between the barrier- and well-doped samples.
First-principles study of magnetism and phase stabilities of V2 based antiferromagnetic Heusler alloys
Authors: Kuroda F. , Fukushima T. , Oguchi T.
Published: May 2020

We investigate the phase stability and magnetism of V2 based antiferromagnetic semiconductors by first-principles calculations. We first analyze the phase stability of the designed alloys by calculating the convex hull and find that keeping Al atoms in the Z sites is crucial to guarantee the stability against the segregation. The V2YAl (Y=V, Nb, and Ta) systems have relatively small hull distances and Néel temperatures higher than 1000 K are evaluated. The strong antiferromagnetic coupling between V atoms is rapidly decreasing with increasing the number of electrons due to the appearance of ferromagnetic double-exchange interaction. By applying a uniaxial strain to induce tetragonal distortion, a relatively large magneto-crystalline anisotropy energy is obtained for V2TaAl. It is claimed that V2YAl are thought to be good candidates for antiferromagnetic spintronics including gate-tunable magnetic properties.
Dynamical model for the neural activity of singing Serinus canaria
Authors: Herbert Cecilia T. , Boari Santiago , Mindlin Gabriel B. , Amador Ana
Published: May 2020

Vocal production in songbirds is a key topic regarding the motor control of a complex, learned behavior. Birdsong is the result of the interaction between the activity of an intricate set of neural nuclei specifically dedicated to song production and learning (known as the “song system”), the respiratory system and the vocal organ. These systems interact and give rise to precise biomechanical motor gestures which result in song production. Telencephalic neural nuclei play a key role in the production of motor commands that drive the periphery, and while several attempts have been made to understand their coding strategy, difficulties arise when trying to understand neural activity in the frame of the song system as a whole. In this work, we report neural additive models embedded in an architecture compatible with the song system to provide a tool to reduce the dimensionality of the problem by considering the global activity of the units in each neural nucleus. This model is capable of generating outputs compatible with measurements of air sac pressure during song production in canaries (Serinus canaria). In this work, we show that the activity in a telencephalic nucleus required by the model to reproduce the observed respiratory gestures is compatible with electrophysiological recordings of single neuron activity in freely behaving animals.
Fowler–Nordheim tunneling-assisted enhancement of tunneling electroresistance effect through a composite barrier
Authors: Wang Yihao , Zhang Qi , Zhou Jinling , Liu Jiaolian , Ma Zhijun , Zhou Peng , Zhang Tianjin , Valanoor Nagarajan
Published: May 2020

Tunneling behaviors of composite ferroelectric tunnel junctions (FTJs) with a no-polar dielectric (DE) layer thickness from 1 to 4 nm were investigated. It is found that the low-resistance state (ON state) current decreases with the DE thickness, while the high-resistance state (OFF state) current decreases first and then increases. The largest tunneling electroresistance (TER) effect is observed for the 3 nm-thick DE layer, which corresponds to the lowest OFF-state current. Studies on the electron transport mechanisms show that direct tunneling dominates the ON-state tunneling behaviors for all FTJs as well as the OFF state for the thinnest DE layer of 1 nm. While Fowler–Nordheim (FN) tunneling plays a significant role in the OFF-state electron transport for thicker DE thicknesses and reinforces its role with the increasing DE thickness, the weak FN tunneling-assisted low OFF-state current for the 3 nm-thick DE layer relative to the DE layer of 4 nm contributes to the largest TER effect.
Prominent room temperature valley polarization in WS2/graphene heterostructures grown by chemical vapor deposition
Authors: Paradisanos I. , McCreary K. M. , Adinehloo D. , Mouchliadis L. , Robinson J. T. , Chuang Hsun-Jen , Hanbicki A. T. , Perebeinos V. , Jonker B. T. , Stratakis E. , Kioseoglou G.
Published: May 2020

We examine different cases of heterostructures consisting of WS2 monolayers grown by chemical vapor deposition as the optically active material. We show that the degree of valley polarization of WS2 is considerably influenced by the material type used to form the heterostructure. Our results suggest that the interaction between WS2 and graphene (WS2/Gr) has a strong effect on the temperature-dependent depolarization (i.e., decrease in polarization with increasing temperature), with polarization degrees reaching 24% at room temperature under near-resonant excitation. This contrasts with hBN-encapsulated WS2, which exhibits a room temperature polarization degree of only 11%. The observed low depolarization rate in the WS2/Gr heterostructure is attributed to the nearly temperature independent scattering rate due to phonons and fast charge and energy transfer processes from WS2 to graphene. Significant variations in the degree of polarization are also observed at 4 K between the different heterostructure configurations. Intervalley hole scattering in the valence band proximity between the K and Γ points of WS2 is sensitive to the immediate environment, leading to the observed variations.
Strong violet emission and optical power limiting properties of reduced graphene oxide/MoO3 synergistic composites
Authors: Ramar Venkadeshkumar , Balasubramanian Karthikeyan
Published: May 2020

Herein, we report the synthesis of reduced graphene oxide/molybdenum oxide (rGO/MoO3) via a simple precipitation method to improve the optical nonlinearity of MoO3. The successful materialization of composites was confirmed through x-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy studies. Rietveld refinement was done for the prepared samples to study the structural analysis. The optical studies revealed strong UV absorption and strong violet emission under 330 nm excitation. The mechanism of violet, blue, and green emissions from MoO3 is proposed through molybdenum interstitial related defects. The variation of bandgap in rGO/MoO3 composites was explained by the graphene induced strain on MoO3. The phonon lifetime of each sample was calculated, and it was found to decrease with respect to the rGO concentration, which makes this composite material potentially applicable for several electronic and optical applications. Moreover, energy dependent optical power limiting properties of the prepared MoO3 and rGO/MoO3 nanocomposites were measured by open aperture z-scan using nanosecond Nd-YAG pulsed laser operating at 532 nm excitation. It is found that the rGO/MoO3 nanocomposites have better optical power limiting properties with a good two photon absorption coefficient of 9.0 × 10−10 m/W. This could be attributed to the efficient interfacial charge transfer between MoO3 and rGO.
Flexible measurement of high-order optical orbital angular momentum with a variable cylindrical lens pair
Authors: Lu Jianneng , Cao Chongyang , Zhu Zhuqing , Gu Bing
Published: May 2020

We present a method to measure the high-order optical orbital angular momentum (OAM) with a variable cylindrical lens pair. The optical system consists of two cylindrical lenses with the opposite focal length. It produces a rotating position—spatial frequency transformation of phase modulation by changing the angle between the two cylindrical lenses. With this feature, the method can flexibly measure the OAM states of the vortex beams with different beam waists. The OAM states are determined by the number and direction of dark stripes of the diffraction pattern. The measurements of the topological charge and the radial index of Laguerre–Gaussian mode are demonstrated. As a compact high-order OAM measuring device, the variable cylindrical lens pair may find potential applications in optical communication.
Shortcuts to adiabaticity for an interacting Bose–Einstein condensate via exact solutions of the generalized Ermakov equation
Authors: Huang Tang-You , Malomed Boris A. , Chen Xi
Published: May 2020

Shortcuts to adiabatic expansion of the effectively one-dimensional Bose–Einstein condensate (BEC) loaded in the harmonic-oscillator (HO) trap are investigated by combining techniques of variational approximation and inverse engineering. Piecewise-constant (discontinuous) intermediate trap frequencies, similar to the known bang–bang forms in the optimal-control theory, are derived from an exact solution of a generalized Ermakov equation. Control schemes considered in the paper include imaginary trap frequencies at short time scales, i.e., the HO potential replaced by the quadratic repulsive one. Taking into regard the BEC’s intrinsic nonlinearity, results are reported for the minimal transfer time, excitation energy (which measures deviation from the effective adiabaticity), and stability for the shortcut-to-adiabaticity protocols. These results are not only useful for the realization of fast frictionless cooling, but also help us to address fundamental problems of the quantum speed limit and thermodynamics.
Nonlinear modeling and characterization of ultrasoft silicone elastomers
Authors: Das Asimanshu , Breuer Kenneth S. , Mathai Varghese
Published: May 2020

We introduce a strain-energy based nonlinear hyper-elastic formulation to model the material properties of ultrasoft dielectric elastomers over a wide range of elastic properties, prestretch, and thicknesses. We build on the uniaxial Gent formulation and, under the conditions of equi-biaxial strain, derive an expression for bulge deformation vs pressure. A circular bulge test methodology is developed to experimentally measure the mechanical response of the silicone membranes. The Gent model captures both neo-Hookean and strain-stiffening behaviors and gives predictions that are in agreement with experimental measurements. Membranes with different thinner fractions are characterized over nearly one order of magnitude variation in shear modulus. Stiffer membranes are observed to harden at lower stretch ratios due to the increased fraction of polymer chains in them. The present approach offers a simple and cost-effective procedure for characterizing soft membranes under commonly encountered biaxial deformation conditions.
Peak instability in an elastic interface ferrofluid
Authors: Coutinho Írio M. , Miranda José A.
Published: May 2020

The instability of an elastic interface separating a ferrofluid and a nonmagnetic fluid subjected to an applied magnetic field perpendicular to the initially undisturbed interface is investigated in the effectively two-dimensional environment of a vertical, rectangular Hele-Shaw cell. By using a third-order mode-coupling perturbative scheme, and considering that the elastic interface has a curvature-dependent bending rigidity, the emergence of elastic ferrofluid peaks is detected at the onset of nonlinearities. In this context, the approximate profile of the interface is obtained. It is also shown that the morphology of the resulting peaks is sensitive to changes in a dimensionless magnetoelastic number (relative measure of magnetic and elastic forces), as well as in a bending rigidity fraction parameter, which expresses variations in the bending rigidity with the local interface curvature.
Investigation of liquid metal drop impingement on a liquid metal surface under the influence of a horizontal magnetic field
Authors: Ren Dong-Wei , Wu Shuang , Yang Juan-Cheng , Ni Ming-Jiu
Published: May 2020

Considering the existence of a horizontal magnetic field, we experimentally investigate the process of a liquid metal drop with high surface tension impacting a film of the same liquid. High-speed photography is adopted here to capture the dynamics of the interaction between the drop and the liquid film. We observe three typical outcomes after drop impact on the film, namely, symmetric crown, asymmetric crown, and prompt splashing, among which the asymmetric crown is first discovered by the present experiments. Moreover, the experimental variables, such as the drop size, impact velocity, initial film thickness, and intensity of the magnetic field, are included to study the three outcomes in detail. For crown formation, the external horizontal magnetic field changes the shape of the crown from symmetric to asymmetric during the crown expansion process, while for prompt splashing, the external horizontal magnetic field promotes splashing from the liquid layer where the drop and the liquid film meet and reduces the critical Weber number where prompt splashing occurs. Therefore, the present experimental results conclusively prove that the external horizontal magnetic field affects the process of liquid metal drop impact on a liquid metal film. Finally, by selecting a typical case, we carried out the direct numerical simulation to calculate the distribution of the magnetic-field-induced Lorentz force inside the droplet after impact, which helps us fully understand the phenomena observed.
Low-pass spatial filter based on 3D metamaterial rasorber with wideband absorption at high frequency
Authors: Jia X. Q. , Chen Q. , An Q. , Zheng Y. J. , Fu Y. Q.
Published: May 2020

This paper presents the design and analysis of a low-pass spatial filter which has wideband absorption at high frequency using a 3D metamaterial rasorber (MR). The unit cell of the 3D MR is composed of several stacked layers of square patches with tapered dimensions, which are separated by thin lossy dielectric laminas. Every two adjacent layers’ metallic patches constitute a resonance cavity, and the inside lossy dielectric substrate results in absorption at the resonance frequency. The stacked metal–dielectric laminas construct a frustum pyramid. With the dimensions of the resonance cavities tapering from the bottom layer to the top layer, the pyramid absorbs over their resonance frequencies so that wideband absorption can be achieved. Besides, the incident wave at the frequencies below all these resonance frequencies can transmit through these cavities. Hence, the pyramid also constructs a low-pass spatial filter. The operation mechanism of this 3D MR structure is analyzed from several aspects by numerical simulation, and experimental measurement has also been executed to verify the design. The 3D metamaterial rasorber performs as an absorber in the Ku-band and a low-pass filter below the X-band. The absorption band with absorptivity higher than 80% spans from 12.3 GHz to 18.2 GHz, and the insertion loss at the frequency below 11.1 GHz is less than 0.9 dB.
On the onset of negative lift in a symmetric airfoil at very small angles of attack
Authors: Aguilar-Cabello Jorge , Gutierrez-Castillo Paloma , Parras Luis , del Pino Carlos , Sanmiguel-Rojas Enrique
Published: May 2020

The variation of the lift coefficient in a symmetric airfoil (NACA 0012 profile) at very small angles of attack is studied experimentally and numerically for a range of low chord-based Reynolds numbers, Re. Experimentally, the non-linearity around the zero angle of attack leading to a switch in sign on the lift was observed for a big enough aspect ratio at Re = 40 × 103. The existence of the negative lift for wing models with the biggest aspect ratio suggests that the three-dimensional effects are negligible. Therefore, two-dimensional simulations were performed to understand the cause of the negative lift. For the cases with the negative lift, the flow displays an interesting feature of pre-alignment with the chord upstream of the profile. Furthermore, it was found that the negative lift is directly related to the positive net circulation (anti-clockwise) around the airfoil.
3D scanning and 3D printing AlSi10Mg single crystal mounts for neutron scattering
Authors: Pajerowski Daniel M. , Ng Rachael , Peterson Nathan , Zhang Yuxuan , Stone Matthew B. , dos Santos Antonio M. , Bunn Jeffrey , Fanelli Victor
Published: May 2020

We present methods to quantify sample shapes and generate sample mounts as motivated by the needs of neutron scattering experiments. The 3D sample scanning was performed using photogrammetry and laser scanning, and a comparison is made between the two techniques. The aluminum alloy AlSi10Mg is shown to have favorable properties for many types of mounts used in neutron scattering. Parts were first prototyped with 3D plastic printers, and then, 3D AlSi10Mg prints were made. The final additively manufactured part holds the sample with more points of contact than is possible with traditional manufacturing. The goodness of fit between the mount and sample was measured by x-ray tomography.
Structural and magnetic behavior of Cr2Co(1−x)CrxAl inverse Heusler alloys
Authors: Srivastava Manisha , Gupt Guru Dutt , Nehla Priyanka , Dhaka Anita , Dhaka R. S.
Published: May 2020

We report the structural and magnetic behavior of single phase inverse Heusler alloys Cr2Co(1−x)CrxAl (x = 0, 0.2, and 0.4) by using x-ray diffraction (XRD), Raman spectroscopy, isothermal magnetization, and magnetic susceptibility measurements. Interestingly, the Rietveld refinement of XRD data with space group I4¯m2 reveal a tetragonal distortion with a c/a ratio around 1.38 in these inverse Heusler structures. The bulk compositions have been confirmed by energy dispersive x-ray spectroscopy measurements. The active Raman mode F2g is observed at 320 cm−1, which confirms the X-type Heusler structure, as the A2 and B2 type structures are known to be not Raman active. The area of F2g mode decreases with an increase in the Cr concentration, which indicates that the origin of this mode is due to Co vibrations. The isothermal magnetization data confirm the magnetic moment to be close to zero (≤0.02 μB/f.u.) at ≈70 kOe and the negligible coercive field suggests the fully compensated ferrimagnetic nature of these samples. The susceptibility behavior indicates irreversibility between zero-field and field-cooled curves and complex magnetic interactions at low temperatures.
Degradation in AlGaN-based UV-C LEDs under constant current stress: A study on defect behaviors
Authors: Wang Ying-Zhe , Zheng Xue-Feng , Zhu Jia-Duo , Xu Lin-Lin , Xu Sheng-Rui , Liang Ren-Li , Dai Jiang-Nan , Li Pei-Xian , Zhou Xiao-Wei , Mao Wei , Zhang Jin-Cheng , Ma Xiao-Hua , Hao Yue
Published: May 2020

Defect behaviors in the degradation of AlGaN-based UV-C light emitting diodes (LEDs) under constant current stress have been intensively investigated in this work. It is found that both the reduction of the optical power and the increase in the leakage current are derived from the newly generated Ga vacancy (VGa) along dislocation, based on the evidence of a strong “yellow” emission peak at 515 nm in the photoluminescence spectra and an energy level of 0.25–0.38 eV. More importantly, the defect evolution behind it was determined through the deep level transient spectroscopy, secondary ion mass spectrometry measurements, and density functional theory. VGa is found to be generated by the departure of the unintentionally doped Mg from MgGa along dislocation in the Si-doped region. The high activity of the unintentionally doped Mg under electrical stress can be an essential factor in the degradation of UV-C LEDs. This study not only provides an in-depth insight into the electrical stress-induced degradation in UV-C LEDs but also sheds light on the way for fabricating AlGaN-based devices with high reliability.
ELM control based on modeling of plasma response to n = 2 and n = 3 resonant magnetic perturbation fields in DIII-D
Authors: Yang Xu , Xu Wei , Zhou Lina , He Yuling , Liu Yueqiang
Published: May 2020

Toroidal modeling of plasma response to the resonant magnetic perturbation (RMP) fields, with the n = 2 and 3 configurations (n is the toroidal mode number), is carried out for DIII-D discharge utilizing the MARS-F code. In particular, the relative toroidal phase (coil phase) between the lower and upper rows of the I-coil currents is scanned from −180° to 180°, while computing the plasma response. Both the resistive rotating and ideal static plasma response models have been employed to predict the optimum coil phase with typical safety factor (q95) values that are within the windows for suppressing the edge localized modes (ELMs). Six certain criteria, which are constructed from the MARS-F modeling, are proposed and tested to determine the optimum coil phase. For both plasma response models, it is found that the three criteria, namely, the resonant harmonic field including plasma response at the last rational surface, the maximum amplitude of the plasma displacement due to the peeling mode response, and the normal plasma surface displacement amplitude near the X point, can serve as appropriate indicators for determining the optimum coil phase. It is demonstrated that the even parity RMP coil configuration can better control the ELMs within the typical ELM suppression window in DIII-D tokamak.
Computational aspects of 19F NMR
Authors: Krivdin Leonid B.
Published: May 2020

This review covers most recent advances in computation of 19F NMR chemical shifts and spin – spin coupling constants involving 19F nucleus calculated at different levels of theory. It deals mainly with electronic and stereochemical effects influencing these parameters, with a special emphasis on practical applications of such calculations. For 19F NMR chemical shifts, a good deal of attention is focused on less common solid state studies, in addition to much more popular liquid state data. For spin – spin coupling constants, the main interest is concentrated on the most popular 19F–1H, 19F–13C and 19F–19F couplings providing marked stereochemical behaviour.

The bibliography includes 149 references.

In memory of Professor Rubén Horacio Contreras, to commemorate his achievements in the field of theoretical and computational 19F NMR.
A new concept for the extraction of gas from Permian ultra-deep coal seams of the Cooper Basin, Australia: Expanding Reservoir Boundary Theory
Authors: Dunlop Erik C.
Published: May 2020

An alternative geomechanical reservoir boundary condition is proposed for ultra-deep coal seams of the Cooper Basin in central Australia. This new concept is embodied within the author’s ‘Expanding Reservoir Boundary (ERB) Theory’, which calls for a paradigm shift in gas extraction technology, diametrically opposed to current practices. As with shale, full-cycle, standalone commercial gas production from Cooper Basin ultra-deep coal seams requires a large stimulated reservoir volume (SRV) having high fracture surface area for gas desorption. This goal has not yet been achieved after 13 years of trials because, owing to the bipolar combination of shale-like reservoir properties and coal-like geomechanical properties, these poorly cleated, inertinitic coal seams exhibit ‘hybrid’ characteristics. Stimulation techniques adopted from other play types are incompatible with the highly unfavourable combination of nanoDarcy-scale permeability, ‘ductility’ and high stress. Nevertheless, gas flow potential counterintuitively increases with depth, contingent upon the creation of an effective SRV. Optimum reservoir conditions occur at depths beyond 9000 feet (2740 m), driven by dehydration, high gas content, gas oversaturation, overpressure and a rigid host rock framework. The physical response of ultra-deep coal seams and the surrounding host rock to pressure drawdown is inadequately characterised. It remains to be established how artificial fracture and coal fabric aperture width change due to the competition between desorption-induced coal matrix shrinkage and compaction caused by increasing effective stress. Studies by the author suggest that pressure arching may ultimately control gas extraction efficiency. Harnessing this geomechanical phenomenon could resolve the technical impasse that currently inhibits commercialisation. Pressure arching neutralises SRV compaction by deflecting stress to adjacent strata of greater integrity. These strata then function as an abutment for accommodating increased stress outside the SRV. This shielding effect allows producing ultra-deep coal seams to progressively de-stress and ‘self-fracture’ naturally, in an overall state of shrinkage-induced tensile failure. An ‘expanding reservoir boundary and decreasing confining stress’ condition is generated by the combined, mutually sustaining actions of coal matrix shrinkage and sympathetic pressure arch evolution. This causes the SRV to steadily increase in size and permeability. Cooper Basin ultra-deep coal seams may be effectively stimulated by harnessing this self-perpetuating, depth-resistant mechanism for creating permeability and surface area. The ultra-deep coal seams may be induced to pervasively ‘shatter’ or ‘self-fracture’ naturally during production, independent of ‘brittleness’, analogous to the manner in which shrinkage crack networks slowly form, in a state of intrinsic tension, within desiccating clay-rich surface sediment.
The case for shared infrastructure to unlock onshore resources
Authors: Eberspaecher Kai C.
Published: May 2020

This paper outlines the current state of the upstream industry for smaller oil and gas developers in Australia’s mature onshore basins. In particular, a strategic review of the market landscape based on Porter’s Five Forces model is undertaken from a junior exploration company’s perspective with a focus on barriers to market entry, such as access to infrastructure, capital, assets and expertise. In the strategic framework context, the paper examines the opportunities to break down natural monopolistic structures and barriers to entry across incumbent producers, pipeline transportation companies and contractors. It also investigates potential changes in resource policy dealing with access to infrastructure and general development requirements. In its analysis, the importance of junior explorers to extend the longevity of mature basins by looking at other petroleum provinces around the globe is highlighted. Examples in North America (onshore) and the UK (offshore) are used to showcase approaches in assisting smaller companies converting resources into reserves. In its conclusion, the paper demonstrates qualitatively how shared infrastructure, coopetition and incorporating renewables can be game changers for junior explorers in unlocking further resources and new prospects in the Australian onshore hydrocarbon provinces. The paper also calls for further coordination between companies, industry bodies and government under an improvement framework to ensure continued success.
The effect of gravity on the shape and direction of vertical hydraulic fractures
Authors: Salimzadeh Saeed
Published: May 2020

Australia has great potential for shale gas development that can reshape the future of energy in the country. Hydraulic fracturing has been proven as an efficient method to improve recovery from unconventional gas reservoirs. Shale gas hydraulic fracturing is a very complex, multi-physics process, and numerical modelling to design and predict the growth of hydraulic fractures is gaining a lot of interest around the world. The initiation and propagation direction of hydraulic fractures are controlled by in-situ rock stresses, local natural fractures and larger faults. In the propagation of vertical hydraulic fractures, the fracture footprint may extend tens to hundreds of metres, over which the in-situ stresses vary due to gravity and the weight of the rock layers. Proppants, which are added to the hydraulic fracturing fluid to retain the fracture opening after depressurisation, add additional complexity to the propagation mechanics. Proppant distribution can affect the hydraulic fracture propagation by altering the hydraulic fracture fluid viscosity and by blocking the hydraulic fracture fluid flow. In this study, the effect of gravitational forces on proppant distribution and fracture footprint in vertically oriented hydraulic fractures are investigated using a robust finite element code and the results are discussed.