bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality Of Life in Stroke Patients - A Qualitative Study
Authors: Shetty Soniya , Kundapur Rashmi ,   Sricharan
Published: April 2020

Introduction: In India stoke is a leading cause of death and acquired human disability. A review of stroke outcome measures in 174 acute stroke trials showed that death was recorded in 76%, impairment in 76%, disability in 42% and handicap in only 2%. One dimension that is rarely measured is health-related quality of life (HRQOL) which aims to assess the impact of disease from the perspective of the patient. Although there is an association between neurological deficits and QL, they are not synonymous.

Objectives: study the health related quality of life with patients of stoke within 3 months of stroke.

Methodology: Study Settings: Hospital based study- A continuation of Stroke Registry

Sample Size: We took 20 patients from the registry

The patients with fresh stoke attack and also who were attending the follow up within the first 3 months of the attack was enrolled into the study. Basic demographic data and the data of stroke outcomes were taken. HRQOL was evaluated using the WHO BREF.

Results: It was seen that majority (55%) of patients expressed a fair physical domain post stroke. About 40% were of opinion that their physical domain was poor. Assessing the psychological domain, majority of the patients said it was poor, 40% said that it was fair. About half (50%) of the patients showed that they had poor environmental domain, whereas only 35% it was fair.

Conclusion: The quality of life is hampered by stroke in majority of the patients.
Enhancement of Flexural Strength of Two Nano-composites by Electron Beam Irradiation
Authors: Hegde Mithra N. , Shetty Preethesh , Bhat Raksha , Mathew Tony
Published: April 2020

Aim: The study aimed to assess and investigate the effect of electron beam irradiation on the flexural strength of two newer nanocomposites (Filtek Z350XT and Filtek Bulkfill)

Materials and Methods: Forty samples each of both the nanocomposites were prepared on rectangular bar shaped moulds (25*2*2mm) according to ISO 4049. The dosage of electron beam selected for the study were 2KGy, 4KGy and 10KGy. The forty specimens were divided into four groups based on the radiation doses; group I: non radiated, group II: 2KGy , group II: 4 KGy, group II: 10KGy with ten samples in each group. The samples were subjected to a 3point bend test on a universal uniaxial servo mechanical testing machine.

Results: The data was statistically analyzed using One way Anova analysis. Analysis demonstrated that Filtek Z350XT had better flexural strength than Filtek Bulkfill (P<0.001). The flexural strength of the composites increased with the dose of electron beam irradiation.

Conclusion: Within the limitations of the study, it can be concluded that the electron beam irradiation of the nanocomposites can be used as a tool to enhance their mechanical properties.
Evaluation of the Influence of Various Sprue Designs on Surface Porosity and Dimensional Accuracy of Base Metal Alloy Castings - An In Vitro Study
Authors: R. Nirupama , Shetty Manoj , D. Krishna Prasad , Hegde Rakshith
Published: April 2020

Background and Objectives: Marginal fit of cast restoration is a major factor in long term survival of restoration. The sprue design is one of the variables that affect successful castings. Porosity can occur both on the surface and sub-surface of the casting. Base metal alloys have been used as an alternative to traditional high gold content alloys due to their superior mechanical properties.

The purpose of this study was to evaluate and compare the influence of various sprue designs on surface porosity and dimensional accuracy with conventional sprue design on five-unit singlepiece base metal alloy castings.

Materials and Method: A metal die that stimulate a five unit Fixed partial denture was fabricated. Three different types of sprue designs was assigned to the pattern and casted. The marginal discrepancy was determined by measuring the space between the margin of the crown and the shoulder finish line of the abutment using Scanning electronic Microscope(100X magnification). Surface porosity was evaluated using stereomicroscope (X10 Magnification).

Results: Best marginal fit based on the grand means and standard deviations was in the conventional design group followed by experimental 4mm and 3mmsprue design. Significant differences was present in the 3mm sprue when compared with 4mm sprue(<0.001) as well as the conventional design(<0.001).

Interpretation and Conclusion: There was no surface porosity observed under stereomicroscope. When marginal discrepancy was compared with conventional design, 4mm single sprue was more effective than the 3mm single sprue.
A Comparative Study on Factors Leading To Early Weaning Among Urban and Rural Mothers of Infants in Selected Community Areas at Mangalore
Authors: Jose Teena J. , R. Sujatha
Published: April 2020

Early weaning is considered as one of the major health issue and it is recognized as the one of the leading cause of mortality and morbidity of infants in many developing countries. A comparative study was done to identify the factors leading to early weaning among mothers of infants in selected areas at Mangalore. Non probability sampling technique and purposive sampling method was used to select 70 early weaned mothers from 300 screened mothers residing at urban area and 50 early weaned mothers from 300 screened mothers of children less than 1 year of age from rural areas at Mangalore. The findings of the study show that there is a significant difference in the number of early weaned mothers of infant when comparing to the urban and rural areas. Hence it is concluded that the early weaning is more common in urban area than in the rural area.
Techniques to Analyze the Effects of Radiation Therapy on Enamel and Dentin - A Review
Authors: Hegde Mithra N. , Hegde Nidharsh D. , N. Suchetha Kumari , Sanjeev Ganesh , G. Priya , Attavar Shruthi
Published: April 2020

Radiation therapy is a most common source in the treatment of Head and neck cancers. The therapy has a positive outcome in curing patients out of danger at an effective rate. But there are few major and minor side effects of the treatment which will possibly hinder the quality of life. One such major concern followed with the therapy is Radiation related caries. Radiation is known to damage the tissues of the teeth making it more susceptible for caries. Hence this review article details on techniques that is being used to test the mechanical and morphological properties of the teeth. The changes observed in these tissues after radiation treatment will enable us to understand the causes for caries. therefore further research in this field is necessary to develop strategies that will probably prevent radiation caries in future days.
Racing against Time: Huge Multiple Mass on the Neck
Authors: Kurian Vinay Babu , Shetty Anil , S. Raveendra U.
Published: April 2020

Defining, describing and identifying 'difficult' airways are difficult tasks. The majority of difficult patients that anesthesiologists encounter look 'more-or-less' normal. Anesthesiologists must be prepared to adapt their technique if difficulty occurs. There can be no doubt that the advent of the laryngeal mask airway (LMA) has decreased the frequency of difficulty with the airway. Flexible fiberoptic in tubation is a tremendously useful technique, which every anesthesiologist should attempt to master. The advantage of vision, the pre-eminent sense, needs no explanation.
Efficacy of Evidence Based Practice (EBP) Guideline to Prevent and Treat Breast Engorgement among Post Caesarean Mothers in Selected Hospital in Mangalore
Authors: Thomas Timi , Devi Elsa Sanatombi , George Linu Sara
Published: April 2020

Introduction: Early initiation of breast feeding has long been recognized as one of the most important contributor to mothers' as well as infants' health. Breast feeding should be initiated within half an hour and two hour of birth in normal vaginal delivery and caesarean section respectively. A recent systematic review regarding the timing of breast feeding initiation shows that if newborns are exposed to breast feeding at the early stage, they are much more likely to adhere to breast feeding and ultimately have better outcome in terms of less incidence of breast engorgement.

Objectives: The objectives of the study were to identify the early initiation of breast feeding by post caesarean mothers using observational check list, to train the staff nurses regarding the EBP guideline to prevent and treat breast engorgement among post caesarean mothers, to find the difference between pre test knowledge score and post test knowledge score among staff nurses on prevention and treatment of breast engorgement using structured knowledge questionnaire, to assess the effectiveness of EBP guideline to prevent and treat breast engorgement among post caesarean mothers in terms of reduction in the severity of breast engorgement before and after the implementation of EBP guideline using modified six point engorgement scale.

Methods: In this study, one group pre test post test design was chosen. The study was conducted at KMC Hospital Attawar, Mangalore. The population in this study comprised of prime post cesarean mothers and staff nurses who are available at the period of data collection at KMC Hospital, Attawar, Mangalore. The calculated sample size for post caesarean mothers is 50 ad staff nurses are 20. The following tools were used to collect the data from the study samples. 1) Baseline characteristics - post caesarean mothers and staff nurses 2) Structured knowledge questionnaire on prevention and treatment of breast engorgement 3) Observational checklist to identify early initiation of breast feeding 4) Modified six point engorgement scale to assess the severity of breast engorgement. The data were collected and analyzed by using descriptive and inferential statistics by SPSS package version 16.

Results: The study results shows, Out of the 50 mothers, 26 (52%) of the mothers had previous information regarding breast engorgement. 14 (53%) of the mothers had received information from family members/ relatives and friends meanwhile 8 (31%) had mass media as a source of information and 4 (16%) had information from their health professionals. Most of the post caesarean mothers were practicing early initiation of breast feeding. Regarding the total practice score for the early initiation of breast feeding it was 6.38 ± 0.696 and it ranged from 5 to 7 with a median 6.

Conclusion: The study has revealed that, most of the post caesarean mothers were practicing the early initiation breast feeding practices.
Internet addiction among the undergraduate students
Authors: Rajeswari C. , Ramachandra Ramachandra , Joseph Nimishamol , George Nivya , K. Pavithra , Syhly Penini , Jose Prinu
Published: April 2020

Background: Internet addiction is an alarming issue which has significant impact on the lifestyle of people. Younger generation need to use internet judiciously and productively to prevent the underlying risks ahead.

Aim: To assess the degree of internet addiction among undergraduate students.

Methods: Using a non-experimental descriptive cross sectional research design, internet addiction was assessed among 200 undergraduate students studying at selected colleges in Bangalore city using Internet Addiction Scale.

Results: Forty nine percent (98) of the undergraduate students had mild addiction, 28.5% (57) were moderately addicted, and 0.5% (1) was severely addicted. No addiction was identified in 22% (44).

Degree of internet addiction was significantly associated with gender, course of study, level of education, religion, educational status of parents, total number of children in the family and internet use of significant others.

Conclusion: Though the intensity of addiction varies, majority of the undergraduate students studied were addicted to internet. Awareness about this addictive behaviour and timely intervention can protect this productive group of the society from the harmful effect of this internet addiction.
Compartment Syndrome- Controversies and where are we Today
Authors: Shetty M. Shantharam , Kumar Ajith , Shetty Lathika , Palanivel Anbuchezhian
Published: April 2020

Compartment Syndrome in Orthopedic practice is a night mare and has to be diagnosed and treated as an emergency to save the function of the limb. Importance of different criteria of early diagnosis, compartment pressure measurement and immediate fasciotomy are the controversies even today. The review emphasizes the importance of these concerns.

Definition

Compartment syndrome occurs due to an increased interstitial tissue pressure inside a closed 1 space especially in an osseo-fascial compartment , should be treated as an acute emergency.
Transdermal Iontophoresis on Gerhardt-Mitchell's Disease of Joints - A rear case report
Authors: S. Mallikarjunaiah H. , U. Dhanesh Kumar K. , Burji Shilpa Dugani
Published: April 2020

Gerhardt-Mitchell's disease which is also named as Erythromelalgia is an unusual neurovascular pain syndrome which features with group of three characteristics i.e., raise in temperature, red color pigmentation of skin and pain with a quality of burning. All three characteristics are most importantly seen in the extremities. Erythromelalgia may occur either as a primary or secondary disorder. Clinical presentation of primary erythromelalgia is linked with severe burning pain, pronounced erythemaof the skin, swelling and increased skin temperature, specifically of the feet. We present the case of a patient, 12 years old girl with primary erythromelalgia who came to our physiotherapy department with features of repeated redness, burning pain, increased warmness of the skin on anterior aspect of right foot. Computer Assisted Capillary Microscopy demonstrated reduced capillary density and capillary perfusion. Another observatory test was done by elevating patient's right leg noting the reversal in skin color from red to pale.Her detailed evaluation was carried out and physiotherapy treatment was started.
Use of Rotational Flap for Reconstruction of Scalp Avulsion Defect - A Case Report
Authors: Vishwanath Karthik , Shetty Nikhil , Roy Satadru
Published: April 2020

Reconstruction of scalp defects is required for acute trauma, tumor extirpation, radiation necrosis, and the repair of traumatic alopecia or cosmetically displeasing scars. The proper choice of a reconstructive technique is affected by several factors—the size and location of the defect, the presence or absence of periosteum, the quality of surrounding scalp tissue, the presence or absence of hair, location of the hairline, and patient comorbidities.Cosmetic scalpreconstruction requires restoration and preservation of normal hair patterns and hair lines.

The scalp vertex is an area of limited scalp mobility and requires extensive undermining and recruitment of tissue from the more mobile anterior, parietal, and occipital regions. The only 2 alternative for large defects (greater than 25 cm2 ) is large rotation-advancement flaps which require near complete scalp undermining.

This article presents a case of Acute scalp Avulsion in the Vertex and the subsequent reconstruction using a large posteriorly based Rotation-Advancement Flap.
Clinical effect of pro-biotic containing Bacillus coagulans on plaque induced gingivitis : A randomised clinical pilot study
Authors: K. Maithri Jagadeesh , Shenoy Nina , Talwar Avaneendra , Shetty Smitha
Published: April 2020

Objectives: To evaluate the clinical effect of Bacillus coagulanson plaque induced gingivitis.

Method: Thirty subjects with plaque induced were enrolled in the study. At baseline, Gingival Index (GI) and Plaque Index (PI) were assessed. Saliva samples were collected for glutathione peroxidise (GPx) activity analysis and to determine load of lactobacilli. Subsequently participants were randomly provided with chewable tablets to be consumed 3 X daily for 3 month containing 100 million colony forming units (CFU)/tablet of B. coagulans or without B. coagulans (placebo). After3 months, recording of GI, Pl and saliva sampling were repeated.

Results: At baseline, mean GI, and mean Pl did not differ significantly between both groups. At re-evaluation, mean GI, and bleeding on probing of the probiotic group were both significantly (p < 0.0001) lower than in the placebo group. Mean PI level did not differ significantly between the groups. In the probiotic group, mean glutathione peroxide activity (Gpx)was significantly (p < 0.02) lower than in the placebo group at re-evaluation.

Conclusion: The consumption of probiotic containing Bacillus coagulans seems to modulate inflammatory response in plaque induced gingivitis.
Perception of facial profile attractiveness by orthodontists and general public in Dakshina Kannada population
Authors: Mohammed Azhar , Shetty Akhil , Nayak U.S Krishna , Shetty Prajwal , Mendonca Mcqueen , Shashidhar Keerthan
Published: April 2020

Background: The purpose of this study was to assess and determine the perception of facial profile attractiveness by orthodontists and general public using Silhouette method. In addition, the orthodontists and the general public (laypeople) compared the facial profile components that they considered desirable for males and females

Methodology: 30 Subjects in the age group of 18-25 years who met all the inclusion and exclusion criteria's were selected from a local Dakshina Kannada Population. After examining each subject for his/her dental occlusion and facial profiles, profile photographs of the subjects were taken. These photographs were shown to Orthodontists and laypeople for their approval, and a subject with the most pleasing profile was selected. After the subject was selected, a lateral cephalogram was taken and various angular and linear measurements were recorded. Using the average values recorded, an androgynous facial Silhouette was constructed. These facial Silhouettes (30) were evaluated by 50 Orthodontists and 50 laymen from local population.

Result: Perception differences were noted between males and females or among Orthodontists and laypeople. No statistically significant difference (P > 0.05) was reported in all series of profiles selection for most preferred and least preferred profile among Orthodontists and laypersons and between males and female profiles.

Conclusion: This study showed the perception of well balanced and imbalanced faces. In some of the variables, there was a clear contrast in preference of profiles for males and females by the Orthodontists and laypeople, while in some variables it was not. A universal standard of facial aesthetic is not applicable to diverse populations.
Ankle Synovial Chondromatosis: case report of 2 cases with 139 and 12 lose bodies treated arthroscopically
Authors: Shetty M. Shantharam , Kumar M. Ajith , K. Yogesh , Doshi Karan
Published: April 2020

Synovial chondromatosis is an uncommon, benign neoplastic nodular cartilaginous lesion of the synovium that can lead to lose bodies and arthritic degeneration if left untreated. We report the case of 2 patients with primary Synovial chondromatosis of the ankle with 139 and 12 loose bodies, respectively, who were treated arthroscopically. Both patients had successful outcomes without recurrence or malignancy, after excision of the lesions. We have reported the highest number of loose bodies (i.e. 139) in the ankle extracted arthroscopically. To conclude, Synovial chondromatosis, although benign, needs detailed investigations to rule out secondary causes and timely intervention to prevent further consequences. Arthroscopic treatment provides easy access and allows early return to activities.

Level of clinical evidence: 4- Case Report.
Two Phase Therapy for Class II Division 1 Malocclusion - A Case Report
Authors: Sinha Suraj Prasad , Shetty Akhil , Ravi M. S. , Nayak U.S. Krishna
Published: April 2020

A 13 year old growing male reported with a complaint of forwardly placed upper front teeth. The case was diagnosed to be Skeletal Class II due to retrognathic mandible. Since the patient was in the growing phase, two phase treatment was planned. The First phase comprised of mandibular advancement using TWIN BLOCK. The final finishing and detailing was achieved in the Second phase of treatment using 0.022 MBT Prescription (self-legating) to produce well-aligned arches in good function and aesthetics.
A MULTIDISCIPLINARY APPROACH FOR FUNCTIONAL REHABILITATION OF A PATIENT WITH SKELETAL CLASS III MALOCCLUSION AND AMELOGENESIS IMPERFECTA
Authors: Shetty Archana S , D. Krishna Prasad , Ravi M S , Prasad B Rajendra
Published: April 2020

Amelogenesis Imperfecta has been defined as a group of hereditary enamel defects not associated with evidence of systemic disease. Restoration for patients with this condition should be oriented toward the functional and esthetic rehabilitation and the protection of these teeth. The specific objectives of the treatment were to enhance esthetics, eliminate tooth sensitivity and restore masticatory function. Management of a patient with skeletal class III malocclusion and Amleogenesis Imperfecta is a challenge for the clinician. Surgical correction of the skeletal class III malocclusion, orthodontic therapy followed by full mouth rehabilitation as a multidisciplinary approach is vital for the functional rehabilitation of the patient.
DOUBLE SUPERIORVENACAVA AND ITS ASSOCIATED CLINICAL IMPLICATIONS - A CASE REPORT AND LITERATURE REVIEW
Authors: Kotian Sushma R , Souza Antony Sylvan D , Ravichandran Praveena , Bhat Pallavi , Hosapatna Mamatha
Published: April 2020

Abnormalities of the vascular system are always of extreme interest due to its importance in circulation. Normally the superior vena cava is a single vascular structure formed by the union of right and left brachiocephalic veins which are in turn formed by the union of corresponding internal jugular and subclavian veins, draining the head and neck as well as the superior extremity. However during routine dissection in the Department of Anatomy, Kasturba Medical College, Manipal, we came across a case of double superior vena cava with persistent left superior vena cava in a 58-year-old male cadaver. Both the vena cavae were formed as continuations of brachiocephalic veins of the corresponding side. The persistent left superior vena cava opened into the enlarged coronary sinus that drained into the right atrium between the opening of inferior venacava and right atrioventricular orifice. No communication was observed between the two vena cavae. A persistent left superior vena cava does not by itself produce any physiological derangement. But it has important clinical implications in certain clinical interventions. It may complicate placement of cardiac catheters or pacemaker leads. Awareness of this anomaly may therefore reduce confusions and thus would help to avoid further complications.
RECURRENT PYOGENIC GRAULOMA - A CASE REPORT
Authors: Ramesh Amitha , Prakash Agumbe Priyanka
Published: April 2020

A non-specific, conditioned gingival enlargement, pyogenic granuloma is a reactive lesion that can occur anywhere on mucosa or skin. In the oral cavity, the gingiva is the most frequent site. The recurrence rate is up to 15%. The most common cause of pyogenic granuloma is local irritating factor. This case report describes a recurrent pyogenic granuloma in a 35 year old patient and its successful surgical management.
Case Report: Intrahepatic Cholestasis of Pregnancy
Authors: D'silva Precilla , Lobo Jasmine Maria , Babu Akhila Mol
Published: April 2020

Intrahepatic cholestasis of pregnancy (ICP) is a cholestatic disorder characterized by pruritus, elevated serum aminotransferases and bile acid levels with gradual onset in the second or third trimester of pregnancy, and spontaneous relief of signs and symptoms within two to three weeks after delivery.
Emergent behaviors of a first-order particle swarm model on the hyperboloid
Authors: Ha Seung-Yeal , Hwang Seungsu , Kim Dohyun , Kim Sun-Chul , Min Chanho
Published: April 2020

We study the emergent dynamics of a first-order particle swarm model (PSM) on the hyperboloid with a constant negative curvature that corresponds to the special case (p, q) = (1, d) of the PSM on the indefinite special orthogonal group SO(p, q) in the work of Ritchie et al. [Chaos 28, 053116 (2018)]. For the proposed PSM on the hyperboloid, we first establish the global existence of a solution via the extension of a local solution to a global one by the continuity argument and then show that the solutions are uniformly bounded by a quantity only depending on the initial data and the coupling strength although the underlying manifold is not compact. In this paper, we consider both attractive and repulsive couplings. For an attractive regime, we show that the complete synchronization occurs for all initial data, whereas for a repulsive regime, we show that distances between particles diverge to infinity, as time goes on. Finally, we present several numerical results consistent with our theoretical results.
A hybrid wind speed forecasting model using stacked autoencoder and LSTM
Authors: Jaseena K. U. , Kovoor Binsu C.
Published: April 2020

Fossil fuels cause environmental and ecosystem problems. Hence, fossil fuels are replaced by nonpolluting, renewable, and clean energy sources such as wind energy. The stochastic and intermittent nature of wind speed makes it challenging to obtain accurate predictions. Long short term memory (LSTM) networks are proved to be reliable models for time series forecasting. Hence, an improved deep learning-based hybrid framework to forecast wind speed is proposed in this paper. The new framework employs a stacked autoencoder (SAE) and a stacked LSTM network. The stacked autoencoder extracts more profound and abstract features from the original wind speed dataset. Empirical tests are conducted to identify an optimal stacked LSTM network. The extracted features from the SAE are then transferred to the optimal stacked LSTM network for predicting wind speed. The efficiency of the proposed hybrid model is compared with machine learning models such as support vector regression, artificial neural networks, and deep learning based models such as recurrent neural networks and long short term memory networks. Statistical error indicators, namely, mean absolute error, root mean squared error, and R2, are adopted to assess the performance of the models. The simulation results demonstrate that the suggested hybrid model produces more accurate forecasts.
Chemical sensing properties of indium-tin-oxide (ITO) printed films fabricated on biodegradable plastics
Authors: Ko Dongwan , Choi Junseck , Seo Joonyoung , Noh Jaeha , Lee Sangtae , Jung Jung-Yeul , Lee Moonjin , Chang Jiho
Published: April 2020

A chemical sensor was fabricated using indium-tin-oxide (ITO) films printed on biodegradable plastic substrates. The ITO layers were printed on polylactic acid (PLA) films. To optimize the printing procedure, the thermal properties of the PLA substrate were investigated using the differential scanning calorimetry method. The structural and electrical properties of the fabricated ITO films (P-ITO) were compared with commercial sputtered ITO films (S-ITO). X-ray diffraction and Hall effect measurements were used to estimate the grain size and the carrier transportation mechanism of the ITO films. The small grain size of P-ITO was attributed to its scattering mechanism. Grain boundary scattering was shown to be dominant in the P-ITO. The chemical sensing properties were also evaluated using a droplet of methanol (20 µl), indicating that the response rate of the P-ITO film was considerably higher (650%) than that of the S-ITO film. These results were attributed to the large surface area of the P-ITO film.
Smaller antenna-gate gap for higher sensitivity of GaN/AlGaN HEMT terahertz detectors
Authors: Sun Jiandong , Feng Wei , Ding Qingfeng , Zhu Yifan , Zhang Zhipeng , Li Xiang , Qin Hua , Zhang Jinfeng , Li Xinxing , Shangguan Yang , Jin Lin , Sun Yunfei , Popov V. V.
Published: April 2020

We report an attempt to improve the sensitivity of terahertz detection based on self-mixing in antenna-coupled field-effect transistors by enhancing the field-effect factor and the antenna factor with a reduced gate length and a reduced antenna-gate gap, respectively. An optical noise equivalent power (NEP) of 3.7 pW/Hz at 0.65 THz was achieved in a GaN/AlGaN high-electron-mobility transistor (HEMT) with a gate length of 300 nm and an antenna-gate gap of 200 nm at room temperature. It was found that the antenna factor was inversely proportional to the antenna-gate gap, and the responses upon coherent/incoherent terahertz irradiation were well described by the self-mixing model. To fill the NEP gap of 0.1−1 pW/Hz between room-temperature and cryogenic detectors by HEMT-based detectors at room temperature, impedance match needs to be carefully considered.
Single-step maskless nano-lithography on glass by femtosecond laser processing
Authors: Zhang Jihua , Cong Cong , Guo Chunlei
Published: April 2020

Femtosecond laser processing is widely adopted today for microfabrication because of its ability to make rapid processing on almost all types of materials in ambient environment. However, it is challenging to apply femtosecond lasers for high-speed large-scale subwavelength nanofabrication, particularly, for two-dimensional nanopatterning on transparent dielectric materials due to their low light absorption. Previous demonstrations of femtosecond laser two-dimensional nanofabrication on dielectrics typically lack structural quality and long-range uniformity. In this work, we report a maskless laser nano-lithographic technique to fabricate high-quality two-dimensional periodic nanodomes on glass. The glass sample is first coated with a thin copper film and then irradiated by femtosecond laser pulses. We show that the period and size of the nanodomes can be controlled using a multi-fluence process. More importantly, a single-fluence technique is developed here, for the first time, for high-quality nanopatterning on glass. The nanopatterning formation mechanism is studied by dynamics experiments and numerical simulations. This introduced technique will provide a simple but highly effective way for dielectrics nanofabrication.
Wavelength dependence of the second harmonic generation of percolating gold thin films
Authors: Konzelmann Annika , Gompf Bruno , Dressel Martin , Berrier Audrey
Published: April 2020

We study the spectral dependence of the second harmonic generation (SHG) emitted by gold thin films around percolation. Previous studies found that the SHG peaks sharply at the percolation regime, i.e., at the critical layer thickness where the static permittivity of the film diverges. Another important characteristic is the very large field enhancement obtained in the regime of almost touching particles, while the thin film does not behave as a metal yet. Here, we show that these properties and, in particular, the amount of SHG extracted are wavelength-dependent. We investigate experimentally the evolution of the SHG as a function of the critical thickness of the film for four different applied fundamental wavelengths. A spectral dependence of the SHG is found, and a simple model is presented that qualitatively reproduces the variations of the measured SHG. We find that the local field enhancement at the fundamental wavelength dominates the signal and also that external factors play a role, such as the film absorbance. These results are particularly interesting for applications requiring an optimization of the SHG.
Combined computational quantum chemistry and classical electrodynamics approach for surface enhanced infrared absorption spectroscopy
Authors: Takenaka Masato , Taketsugu Tetsuya , Iwasa Takeshi
Published: April 2020

Surface enhanced spectroscopy, which enhances the signal intensity of molecules on a surface, facilitates the study of molecular properties, even down to a single-molecule level if a scanning probe is used. To realize the full potential of surface enhanced spectroscopy, a clear theoretical understanding is indispensable. However, quantum chemical calculations for surface enhanced spectroscopy are not simple because of the violation of the widely used dipole approximation. The spatial structure of electric near-field in the close proximity of a surface strongly depends on the geometry of the metal nanostructure as well as on the incident wavelength. Therefore, in principle, a universal model for electric near-field cannot exist. To address this issue, we have developed a generalized light–matter interaction model from first-principles quantum chemical calculations by using the multipolar Hamiltonian, in which the spatial structure of the electric field is fully considered. Here, we incorporate computational electrodynamics for surface enhanced infrared (IR) absorption spectroscopy in the model, where electric near-field around a Ag ellipsoid is obtained and used for IR calculations. Furthermore, we have devised a method to successfully reproduce the peak selectivity observed experimentally.
Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment
Authors: Saric Denis , Kohns Maximilian , Vrabec Jadran
Published: April 2020

The concentration dependence of the dielectric constant and the density of 11 aqueous alkali halide solutions (LiCl, NaCl, KCl, RbCl, CsCl, LiI, NaI, KI, CsI, KF, and CsF) is investigated by molecular simulation. Predictions using eight non-polarizable ion force fields combined with the TIP4P/ε water model are compared to experimental data. The influence of the water model and the temperature on the results for the NaCl brine are also addressed. The TIP4P/ε water model improves the accuracy of dielectric constant predictions compared to the SPC/E water model. The solution density is predicted well by most ion models. Almost all ion force fields qualitatively capture the decline of the dielectric constant with the increase of concentration for all solutions and with the increase of temperature for NaCl brine. However, the sampled dielectric constant is mostly in poor quantitative agreement with experimental data. These results are related to the microscopic solution structure, ion pairing, and ultimately the force field parameters. Ion force fields with excessive contact ion pairing and precipitation below the experimental solubility limit generally yield higher dielectric constant values. An adequate reproduction of the experimental solubility limit should therefore be a prerequisite for further investigations of the dielectric constant of aqueous electrolyte solutions by molecular simulation.
Multiple-frequency perfect absorption by hybrid membrane resonators
Authors: Tang Suet To , Lau Joshua , Yeung Ka Yan Au , Yang Z.
Published: April 2020

Besides generating their own perfect absorption bands, the primary hybrid resonances of a hybrid membrane resonator (HMR) consisting of a decorated membrane resonator (DMR) backed by a cavity can also provide strong assistance for weak resonances to create secondary hybrid resonances and multiple-frequency perfect absorption by forming a low impedance region between the primary hybrid resonances. The weak resonances can be introduced by placing another DMR in front of a HMR or by using a DMR with an off-centered platelet in an HMR. In one such sample, five perfect absorption bands within the range of 200–1000 Hz are experimentally observed with minimum reflection values ranging from 1.2% to 7%.
Efficient evaluation of Coulomb interactions in kinetic Monte Carlo simulations of charge transport
Authors: Pippig Michael , Mercuri Francesco
Published: April 2020

The application of predictive and reliable modeling techniques for the simulation of charge transport in functional materials is an essential step for the development of advanced platforms for electronics, optoelectronics, and photovoltaics. In this context, kinetic Monte Carlo (KMC) methods have emerged as a valuable tool, especially for the simulation of systems where charge transport can be described by the hopping of charge carriers across localized quantum states, as, for example, in organic semiconductor materials. The accuracy, computational efficiency, and reliability of KMC simulations of charge transport, however, crucially depend on the methods and approximations used to evaluate electrostatic interactions arising from the distribution of charges in the system. The long-range nature of Coulomb interactions and the need to simulate large model systems to capture the details of charge transport phenomena in complex devices lead, typically, to a computational bottleneck, which hampers the application of KMC methods. Here, we propose and assess computational schemes for the evaluation of electrostatic interactions in KMC simulations of charge transport based on the locality of the charge redistribution in the hopping regime. The methods outlined in this work provide an overall accuracy that outperforms typical approaches for the evaluation of electrostatic interactions in KMC simulations at a fraction of the computational cost. In addition, the computational schemes proposed allow a spatial decomposition of the evaluation of Coulomb interactions, leading to an essentially linear scaling of the computational load with the size of the system.
Prediction of giant magnetocaloric effect in Ni40Co10Mn36Al14 Heusler alloys: An insight from ab initio and Monte Carlo calculations
Authors: Sokolovskiy V. , Miroshkina O. , Zagrebin M. , Buchelnikov V.
Published: April 2020

In this work, based on limited experimental magnetocaloric data for Ni–Co–Mn–Al Heusler alloys, we present a theoretical study to predict a composition with higher magnetocaloric properties. By analogy with Ni–Co–Mn–(In, Sn) alloys exhibiting a large magnetization change across the structural transformation, we suppose that the addition of 10 at. % Co in Ni–Mn–Al would yield a similar trend. Our approach is based on the combination of ab initio calculations and Monte Carlo simulations within the framework of the Potts–Blume–Emery–Griffiths model. It follows from ab initio calculations that Co addition modifies the exchange interactions and enhances the ferromagnetism in austenite, while for martensite, the ferromagnetism is substantially suppressed due to the strongest antiferromagnetic Mn–Mn interactions. Thermo-magnetization curves and magnetocaloric properties under magnetic fields of 0.5 and 2 T are simulated by the Monte Carlo method assuming the ab initio exchange-interaction parameters. A large change in magnetization of approximately 100 A m2kg−1, leading to a giant magnetocaloric effect (ΔTad≈−7 K) across the martensite–austenite transformation, is predicted.
An analytical theory to describe sequence-specific inter-residue distance profiles for polyampholytes and intrinsically disordered proteins
Authors: Huihui Jonathan , Ghosh Kingshuk
Published: April 2020

Intrinsically Disordered Proteins (IDPs), unlike folded proteins, lack a unique folded structure and rapidly interconvert among ensembles of disordered states. However, they have specific conformational properties when averaged over their ensembles of disordered states. It is critical to develop a theoretical formalism to predict these ensemble average conformational properties that are encoded in the IDP sequence (the specific order in which amino acids/residues are linked). We present a general heteropolymer theory that analytically computes the ensemble average distance profiles (⟨Rij2⟩) between any two (i, j) monomers (amino acids for IDPs) as a function of the sequence. Information rich distance profiles provide a detailed description of the IDP in contrast to typical metrics such as scaling exponents, radius of gyration, or end-to-end distance. This generalized formalism supersedes homopolymer-like models or models that are built only on the composition of amino acids but ignore sequence details. The prediction of these distance profiles for highly charged polyampholytes and naturally occurring IDPs unmasks salient features that are hidden in the sequence. Moreover, the model reveals strategies to modulate the entire distance map to achieve local or global swelling/compaction by subtle changes/modifications—such as phosphorylation, a biologically relevant process—in specific hotspots in the sequence. Sequence-specific distance profiles and their modulation have been benchmarked against all-atom simulations. Our new formalism also predicts residue-pair specific coil-globule transitions. The analytical nature of the theory will facilitate design of new sequences to achieve specific target distance profiles with broad applications in synthetic biology and polymer science.
Thermoelectric modulation by intrinsic defects in superionic conductor AgxCrSe2
Authors: Tang Mingjing , Chen Zhiyu , Yin Cong , Lin Liwei , Ren Ding , Liu Bo , Kang Bin , Ang Ran
Published: April 2020

AgCrSe2 materials have shown the potential to be the promising thermoelectric materials due to the intrinsic ultralow lattice thermal conductivity enabled by the fluid-like motion of Ag ions in crystal structures. However, what important role the Ag point defects can play in promoting liquid-like conduction still remains a mystery. Moreover, understanding the electronic transport properties, specifically for clarifying the contribution of various impurity states, is of critical importance for improving the thermoelectric performance of AgCrSe2. Here, the thermoelectric properties of AgCrSe2 with various Ag content have been systematically investigated. It is found that the carrier concentration can be modulated in a broad range by inducing deep level impurity states, enabling a transition from degenerate semiconductor to nondegenerate one and a reliable evaluation on the thermoelectric transport properties. The single parabolic band model gives a good clarification regarding the increased electronic performance. Furthermore, the enhancement of the liquid-like effect triggered by the Ag vacancies contributes to the ultralow lattice thermal conductivity (∼0.25 W m−1 K−1). Eventually, a maximum figure of merit zT of ∼0.6 is realized in Ag0.97CrSe2 at 750 K. The present findings may shed light on the improvement of thermoelectric performance in AgCrSe2 materials.
Development of an x-ray detector by polycrystalline diamond and its application in Z-pinch x-ray detection
Authors: Yu Y. , Xu P. , Zhou H. Y. , Qiu C. J.
Published: April 2020

Large-grain-sized polycrystalline diamond films are fabricated by electron assisted chemical vapor deposition. A pure SP3 carbon bond in the cubic lattice structure is confirmed by Raman spectrum analysis. The grain size is on the order of several hundreds of μm or larger. Interlaced-finger electrodes are imprinted onto a 6 × 6 mm2 × 500 µm film to fabricate the x-ray detector. The width of every finger is 25 µm, and the distance between nearby fingers is 25 μm. Strong x ray irradiates when a pulsed current flows through a double-layer nested tungsten wire array in the Z-pinch. This diamond detector now works as one of the main x-ray detectors for the Z-pinch device. The diamond detector is calibrated using a plastic scintillator. The comparison between the signal measured by these two methods confirms that the large-grain-sized polycrystalline diamond is a good candidate for the detection of nanosecond pulsed x ray.
World’s physics instruments turn their focus to COVID-19
Authors: Kramer David
Published: April 2020

Scientists are employing x rays, electrons, and neutrons to decipher and disable the molecular machinery of the novel coronavirus.
Magnetic magnesium oxide composites for rapid removal of polycyclic aromatic hydrocarbons and cadmium ions from water
Authors: Tan Dongqin , Jin Jing , Guo Cuicui , Dhanjai  , Chen Jiping
Published: April 2020

Environmental contextRemediation of wastewater containing polycyclic aromatic hydrocarbons and metals is essential to limit adverse effects on the environment and human health. Using a simple precipitation method, we prepared porous magnetic MgO hybrids for use as a material for removing pollutants from wastewater. The material showed excellent removal performance for 12 polycyclic aromatic hydrocarbons and cadmium ions, and thus has potential applications in wastewater treatment.
AbstractHierarchical porous magnetic MgO hybrids (Fe3O4/MgO) are controllably synthesised based on a facile precipitation process. The resulting material displays a three-dimensional architecture with nest-like morphology, large surface area (135.2m2 g−1) and uniform mesochannels (5–35nm). The adsorption equilibrium data of target polycyclic aromatic hydrocarbons (PAHs) on Fe3O4/MgO sorbents are described by the Langmuir isotherm model. The composites show a strong tendency for the removal of PAHs owing to their porous structure that possesses an excellent affinity for PAHs. Under the optimal conditions, a removal of more than 70% is achieved for 12 PAHs. The materials also exhibit a good removal ability of cadmium (Cd2+) from water with fast adsorption (<5min) and high removal percentage (>80%). Moreover, the composites possess sufficient magnetism for separation. To demonstrate the performance of the sorbents, Fe3O4/MgO is exposed to aqueous samples spiked with low concentrations of PAHs and Cd2+. In almost all cases, the composites are superior to the commercially available sorbents as well as un-functionalised Fe3O4 nanoparticles. Therefore, this work provides a promising approach for the simultaneous removal of PAHs and Cd2+ from water using multifunctional MgO microspheres.
Investigating the OECD database of per- and polyfluoroalkyl substances – chemical variation and applicability of current fate models
Authors: Chelcea Ioana C. , Ahrens Lutz , Örn Stefan , Mucs Daniel , Andersson Patrik L.
Published: April 2020

Environmental contextA diverse range of materials contain organofluorine chemicals, some of which are hazardous and widely distributed in the environment. We investigated an inventory of over 4700 organofluorine compounds, characterised their chemical diversity and selected representatives for future testing to fill knowledge gaps about their environmental fate and effects. Fate and property models were examined and concluded to be valid for only a fraction of studied organofluorines.
AbstractMany per- and polyfluoroalkyl substances (PFASs) have been identified in the environment, and some have been shown to be extremely persistent and even toxic, thus raising concerns about their effects on human health and the environment. Despite this, little is known about most PFASs. In this study, the comprehensive database of over 4700 PFAS entries recently compiled by the OECD was curated and the chemical variation was analysed in detail. The analysis revealed 3363 individual PFASs with a huge variation in chemical functionalities and a wide range of mixtures and polymers. A hierarchical clustering methodology was employed on the curated database, which resulted in 12 groups, where only half were populated by well-studied compounds thus indicating the large knowledge gaps. We selected both a theoretical and a procurable training set that covered a substantial part of the chemical domain based on these clusters. Several computational models to predict physicochemical and environmental fate related properties were assessed, which indicated their lack of applicability for PFASs and the urgent need for experimental data for training and validating these models. Our findings indicate reasonable predictions of the octanol-water partition coefficient for a small chemical domain of PFASs but large data gaps and uncertainties for water solubility, bioconcentration factor, and acid dissociation factor predictions. Improved computational tools are necessary for assessing risks of PFASs and for including suggested training set compounds in future testing of both physicochemical and effect-related data. This should provide a solid basis for better chemical understanding and future model development purposes.