Decomposing and Analyzing Contact Resonance Frequency in Contact Mode Voltage Modulated Scanning Probe Microscopies

The contact mode voltage modulated scanning probe microscopy (SPM) techniques, such as switching spectroscopy piezoresponse force microscope (SS-PFM), are powerful tools for detecting local electromechanical behaviors. However, interpreting their signals,...

Correlation between morphology and local mechanical and electrical properties of van der Waals heterostructures

Properties of van der Waals (vdW) heterostructures strongly depend on the quality of the interface between two dimensional (2D) layers. Instead of having atomically flat, clean, and chemically inert interfaces without dangling bonds, top-down vdW heterostructures are associated with bubbles and intercalated layers (ILs) which trap contaminations appeared during fabrication process. We investigate their influence on local electrical and mechanical properties of MoS2/WS2 heterostructures using atomic force microscopy (AFM) based methods. It is demonstrated that domains containing bubbles and ILs are locally softer, with increased friction and energy dissipation. Since they prevent sharp interfaces and efficient charge transfer between 2D layers, electrical current and contact potential difference are strongly decreased. In order to reestablish a close contact between MoS2 and WS 2 layers, vdW heterostructures were locally flattened by scanning with AFM tip in contact mode or just locally pressed with an increased normal load. Subsequent electrical measurements reveal that the contact potential difference between two layers strongly increases due to enabled charge transfer, while local I/V curves exhibit increased conductivity without undesired potential barriers.

Photobiomodulation Therapy Applied after 6 Months for the Management of a Severe Inferior Alveolar Nerve Injury

Despite its significant negative impact on the quality of life, the methods for the management of the inferior alveolar nerve (IAN) injury are still limited. In this case report, the patient did not show any improvement from the day of the iatrogenic accident until 6 months. A significant improvement of the symptoms started to appear only at 6 months when PBMT was applied. A total of 42 sessions of PBMT took place. The application zone included intraoral and extraoral areas. The parameters were: Delivery power of 0.1 W, for 40 s, continuous wave (CW), contact mode, and delivered energy of 4 J. The delivered energy density related to the fiber diameter was 1415 J/cm2. Each treated point was considered to be 1 cm2 of diameter. At the end of the treatment, all of the symptoms disappeared except for an abnormal sensation on touching the mucosa and gingiva of the concerned area. No side effects were noted. This case report shows that PBMT can be a very promising approach for the management of severe cases that are not improving with conventional methods.

Tracing Management and Epidemiological Characteristics of COVID-19 Close Contacts in Cities Around Chengdu, China

Introduction: Close contacts have become a potential threat to the spread of coronavirus disease 2019 (COVID-19). The purpose of this study was to understand the epidemiological characteristics of close contacts of confirmed or suspected cases of COVID-19 in the surrounding cities of Chengdu, China, so as to provide a basis for the management strategy of close contacts.Methods: Close contacts were determined through epidemiological investigation of indicated cases, and relevant information was entered in the “Close Contact Information Management System.” Retrospective data of close contacts from January 22 to May 1, 2020 were collected and organized. Meanwhile, the contact mode, isolation mode, and medical outcome of close contacts were descriptively analyzed.Results: A total of 986 close contacts were effectively traced, with an average age of (36.69 ± 16.86) years old, who were mainly distributed in cities of eastern Chengdu. The frequency of contact was mainly occasional contact, 80.42% of them were relatives and public transportation personnel. Besides, the time of tracking close contacts and feedback was (10.64 ± 5.52) and (7.19 ± 6.11) days, respectively. A total of seven close contacts were converted to confirmed cases.Conclusions: Close contacts of COVID-19 have a risk of invisible infection. Early control of close contacts may be helpful to control the epidemic of COVID-19.

Developing portable widefield fundus camera for teleophthalmology: Technical challenges and potential solutions

A portable, low cost, widefield fundus camera is essential for developing affordable teleophthalmology. However, conventional trans-pupillary illumination used in traditional fundus cameras limits the field of view (FOV) in a snapshot image, and frequently requires pharmacologically pupillary dilation for reliable examination of eye conditions. This minireview summarizes recent developments in alternative illumination approaches for widefield fundus photography. Miniaturized indirect illumination has been used to enable compact design for developing low cost, portable, widefield fundus camera. Contact mode trans-pars-planar illumination has been validated for ultra-widefield fundus imaging of infant eyes. Contact-free trans-pars-planar illumination has been explored for widefield imaging of adult eyes. Trans-palpebral illumination has been also demonstrated in a smartphone-based widefield fundus imager to foster affordable teleophthalmology.

Fabrication of probe tips via the FIB method for nanodiagnostics of the surface of solids by atomic force microscopy

In this work, we carried out an investigation of commercial atomic force microscope (AFM) probes for contact and semi-contact modes, which were modified by focused ion beam (FIB). This method was used to modify the original tip shape of silicon AFM probes, by ion-etching and ion-enhance gas deposition. we show a better performance of the FIB-modified probes in contrast with the non-modified commercial probes. These results were obtained after using both probes in semi-contact mode in a calibration grating sample.

Study of Langmuir monolayers and Langmuir-Schaefer films based on symmetrical meso-aryl-substituted porphyrin derivative

This paper presents the results of a study of meso-aryl-substituted porphyrin Langmuir monolayers by the method of compression isotherms. Experimental data were used to plot the dependences of the compression modulus (C−1) on the specific area. Monolayers at specific surface pressure were transferred to solid substrates and investigated. The monolayers were transferred to the surface of monocrystalline silicon at surface pressures of 8, 25, and 60 mN/m and examined them by atomic force microscopy (AFM) in a semi-contact mode. It was found that with an increase in the transfer pressure, the coarsening of molecular aggregates occurs. The smallest roughness is observed for a porphyrin film formed and transferred at a pressure of 8 mN/m.

Design and Fabrication of Low-Cost Thermal Imaging Device Prototype to Detect Heat Energy Loss in Electrical Equipment

Ability to detect heat energy loss from electrical equipment can be proven crucial to avoid overheating and unexpected fire incident. The thermal remote camera was invented to prevent power outages or electrical machinery failures. Thermal imaging cameras are device which converts thermal energy (heat) into infrared spectrum to inspect a specific object or scene. Imagery that reflects the spatial variability of temperature differences in a scene observed by a thermal camera are called thermal images. Due to the complexity of the device, it can be cost and not a solution sought for. This research presents the designing and fabrication of low-cost thermal imaging cameras that plays major role in detecting heat energy losses in various applications. This prototype of thermal imaging cameras is tested to monitor and diagnose the heat health, especially in electrical installations and components in non-contact mode. Based on the test result presented, the prototype able to detect heat energy spectrum up to 80°C. The 8x8 thermal array able to calculate average temperature of the tested items.

Combined CFA-AFM Analytical approach for precipitation reaction regarding crystal growth building single and multiple monolayers based on surface area calculation with image surface roughness analysis (unseen surface)

A reaction of Mebeverine hydrochloride (0.03mM) in pure form with sodium nitroprusside (0.07mM) to form OFF White precipitate. A constant feed was used to collect an enough amount in weight for AFM study. Continuous flow injection analysis was conducted as it is the aim of this study to combine FIA with AFM. To elucidate the study of surface morphology. Various parameters of AFM image surface roughness analysis were discussed in relation to the kind of precipitate formed. Skewness, kurtosis, peak-peak, ten peak height, fractal dimension, wavelength, core roughness depth, and reduced valley depth. All these with the four parameter mainly amplitude, hybrid, functional and spetial. Since no previous study of such was conducted; all usual mode of imaging was dealt with i.e., contact, non-contact and intermittent contact was defined. A non contact mode was used in this study. A detailed study of how the crystal growth buildup first mono layer (hypothetical based on the date obtained also how much each grain carry a concentration with the number that are on the first mono layer. Number of given samples of surface area calculation plus a demonstration of the hypothetically formed multi mono layers specially at high reactant concentration. The main aim of this project was the binding of AFM with FIA which is regarded as an new approach which might be a very useful knowledge for other researcher.