Study on Influence of Surface Plasma Activation of Quartz Fiber/Cyanate Ester Composite at Meter Range Working Distance

The surface of quartz fiber/cyanate ester composite at meter working distance was activated by plasma treatment technology. Influence of plasma treatment parameters on surface contact angle of the composite was investigated, as well as changes of surface morphology, intrinsic performance and membrane-based bonding strength. Results showed that surface contact angle of the composite decreased significantly after plasma treatment with nitrogen and argon. Moreover, activation effect of argon plasma was better than that of nitrogen plasma. With the increase of voltage, surface contact angle of composite became smaller and activation effect was better. After plasma treatment, glass transition temperature (Tg) and bending strength of the composite did not change, and intrinsic property of the composite was not damaged. After plasma treatment, surface roughness and specific surface area of the composite increased, and membrane-based bonding strength of the composite with Al coating increased significantly.

SmartKC

Keratoconus is a severe eye disease affecting the cornea (the clear, dome-shaped outer surface of the eye), causing it to become thin and develop a conical bulge. The diagnosis of keratoconus requires sophisticated ophthalmic devices which are non-portable and very expensive. This makes early detection of keratoconus inaccessible to large populations in low-and middle-income countries, making it a leading cause for partial/complete blindness among such populations. We propose SmartKC, a low-cost, smartphone-based keratoconus diagnosis system comprising of a 3D-printed placido's disc attachment, an LED light strip, and an intelligent smartphone app to capture the reflection of the placido rings on the cornea. An image processing pipeline analyzes the corneal image and uses the smartphone's camera parameters, the placido rings' 3D location, the pixel location of the reflected placido rings and the setup's working distance to construct the corneal surface, via the Arc-Step method and Zernike polynomials based surface fitting. In a clinical study with 101 distinct eyes, we found that SmartKC achieves a sensitivity of 87.8% and a specificity of 80.4%. Moreover, the quantitative curvature estimates (sim-K) strongly correlate with a gold-standard medical device (Pearson correlation coefficient = 0.77). Our results indicate that SmartKC has the potential to be used as a keratoconus screening tool under real-world medical settings.

ChestLive

Voice-based authentication is prevalent on smart devices to verify the legitimacy of users, but is vulnerable to replay attacks. In this paper, we propose to leverage the distinctive chest motions during speaking to establish a secure multi-factor authentication system, named ChestLive. Compared with other biometric-based authentication systems, ChestLive does not require users to remember any complicated information (e.g., hand gestures, doodles) and the working distance is much longer (30cm). We use acoustic sensing to monitor chest motions with a built-in speaker and microphone on smartphones. To obtain fine-grained chest motion signals during speaking for reliable user authentication, we derive Channel Energy (CE) of acoustic signals to capture the chest movement, and then remove the static and non-static interference from the aggregated CE signals. Representative features are extracted from the correlation between voice signal and corresponding chest motion signal. Unlike learning-based image or speech recognition models with millions of available training samples, our system needs to deal with a limited number of samples from legitimate users during enrollment. To address this problem, we resort to meta-learning, which initializes a general model with good generalization property that can be quickly fine-tuned to identify a new user. We implement ChestLive as an application and evaluate its performance in the wild with 61 volunteers using their smartphones. Experiment results show that ChestLive achieves an authentication accuracy of 98.31% and less than 2% of false accept rate against replay attacks and impersonation attacks. We also validate that ChestLive is robust to various factors, including training set size, distance, angle, posture, phone models, and environment noises.

Ultra-high-speed multi-parametric photoacoustic microscopy

Multi-parametric photoacoustic microscopy (PAM) is uniquely capable of simultaneous, high-resolution mapping of blood hemoglobin concentration, oxygenation, and flow in vivo. However, its speed has been limited by the dense sampling required for blood flow quantification. To overcome this limitation, we have developed an ultra-high-speed multi-parametric PAM system, which enables simultaneous acquisition of ~500 densely sampled B-scans by superposing the rapid laser scanning across the line-shaped focus of a cylindrically focused ultrasonic transducer over the conventional mechanical scan of the optical-acoustic dual foci. A novel optical-acoustic combiner is designed and implemented to accommodate the short working distance of the transducer, enabling convenient confocal alignment of the dual foci in the reflection mode. This new system enables continuous monitoring of microvascular hemoglobin concentration, blood oxygenation, and flow over a 4.5 x 3 mm2 area in the awake mouse brain with high spatial and temporal resolution (6.9 μm and 0.3 Hz, respectively).

Multiplex, translaminar imaging in the spinal cord of behaving mice

While the spinal cord is known to play critical roles in sensorimotor processing, including pain-related signaling, corresponding activity patterns in genetically defined cell types across spinal laminae have remained elusive. Calcium imaging has enabled cellular activity measurements in behaving rodents but is currently limited to superficial regions. Using chronically implanted microprisms, we imaged sensory and motor evoked activity in regions and at speeds inaccessible by other high-resolution imaging techniques. To enable translaminar imaging in freely behaving animals through implanted microprisms, we additionally developed wearable microscopes with custom-compound microlenses. This new integrated system addresses multiple challenges of previous wearable microscopes, including their limited working distance, resolution, contrast, and achromatic range. The combination of these innovations allowed us to uncover that dorsal horn astrocytes in behaving mice show somatosensory program-dependent and lamina-specific calcium excitation. Additionally, we show that tachykinin precursor 1 (Tac1)-expressing neurons exhibit upper laminae-restricted activity to acute mechanical pain but not locomotion.

Trans-segmental imaging in the spinal cord of behaving mice

Spinal cord circuits play crucial roles in transmitting and gating cutaneous somatosensory modalities, such as pain, but the underlying activity patterns within and across spinal segments in behaving mice have remained elusive. To enable such measurements, we developed a wearable widefield macroscope with a 7.9 mm2 field of view, subcellular lateral resolution, 2.7 mm working distance, and <10 g overall weight. We show that highly localized painful mechanical stimuli evoke widespread, coordinated astrocyte excitation across multiple spinal segments.

COMPARISON OF THE EFFICIENCY OF DIFFERENT DETECTORS OF THE SCANNING ELECTRONIC MICROSCOPE «MIRA-LMH» FOR STUDYING MICROSTRUCTURE OF NANOMATERIALS

На первом этапе были синтезированы объекты исследования - диоксид кремния методом Штобера, где в качестве прекурсора использовали тетраэтоксисилан, и нанокомпозит ZnO - Au золь-гель методом с использованием в качестве прекурсора 2 - водного ацетата цинка. На втором этапе, микроструктуру и морфологию полученных образцов исследовали методом растровой электронной микроскопии на сканирующем электронном микроскопе «MIRA-LMH» фирмы «Tescan» с применением как классического детектора вторичных электронов, так и дополнительных детекторов - внутрилинзового детектора вторичных электронов и детектора отраженных электронов. В результате исследований установлено, что при использовании детектора вторичных электронов получаются изображения с топографическим контрастом и практически без шумов. При использовании внутрилинзового детектора вторичных электронов создаются изображения только материального контраста, без влияния рельефа поверхности. Также использование данного детектора позволило получить высококачественные изображения с большим разрешением на расстоянии от образца 5 мм. При использовании детектора отраженных электронов с рабочим расстоянием до образца 8 мм и увеличении разрешающей способности микроскопа, полученные изображения имеют низкий контраст границ, но представляют композиционную информацию с высокой чувствительностью. Таким образом, установлено, что внутрилинзовый детектор вторичных электронов, с рабочим расстоянием до образца 5 мм, является оптимальным для получения четких изображений микроструктры поверхности наноматериалов при многократном увеличении. At the first stage, the objects of study were synthesized - silicon dioxide by the Stober method, where tetraethoxysilane was used as a precursor, and a nanocomposite ZnO - Au by the sol-gel method using the aqueous zinc acetate dihydrate as a precursor. At the second stage, the microstructure and morphology of the obtained samples were investigated by scanning electron microscopy on a «MIRA-LMH» scanning electron microscope (Tescan company) using both a classical secondary electron detector and additional detectors - intralens secondary electron detector and back-scattered electrons detector. As a result of the research, it was found that when using the secondary electron detector, practically no noise images with topographic contrast are obtained. When using the intralens secondary electron detector, images of only material contrast are created, without the influence of the surface relief. Also, the use of this detector made it possible to obtain high-quality images with a high resolution at a distance of 5 mm from the sample. When using a back-scattered electrons detector with a working distance to the sample of 8 mm and increasing the resolution of the microscope, the resulting images have low border contrast, but represent compositional information with high sensitivity. Thus, it was found that the intralens secondary electron detector with a working distance of 5 mm to the sample is optimal for obtaining clear images of the microstructure of the surface of nanomaterials at multiple magnifications.

Behavioral Measures in Myopic and Non-myopic High Schoolers During the COVID Pandemic

Purpose: The purpose of this study is to understand how the visual activity of highschool students in Houston changed due to quarantine and online learning during the COVID-19 pandemic, and whether these behaviors were different between myopes and non-myopes. Methods: Thirty-one participants (16.3±0.8 years, 8 females), including 12 myopes and 8 non-myopes, wore a Clouclip and Actiwatch for a week. The Clouclip records working distance and the Actiwatch measures light exposure, physical activity, and sleep duration. A questionnaire was also completed regarding demographics, ocular history, and visual behaviors. Results: Data showed that myopic participants engaged in near work (working distances of 10 to <60 cm) for 8.4±2.6 hours on a week day and 6.5±2.1 hours on a weekend day. Non-myopic participants engaged in near work for 6.1±2.7 hours on a week day and 4.5±1.9 hours on a weekend day. While weekend near work was significantly different between refractive error groups (P<.05), weekday near work (P=.08) was not. There were no differences between refractive error groups for daily light exposure (P = .89), time outdoors (P = .44), or sleep duration (P = .80). Conclusions: There was no significant change in sleep duration and physical activity regardless of refractive error over the pandemic, while results revealed a significant decrease in outdoor light exposure and the increase in near and intermediate work, especially with electronic devices such as the computer.

Risk Factors Related to Decreased Vision in Primary School Children in Palembang

Introduction. Visual acuity is the ability of the eye to see an object clearly, and this depends on the ability of the eye to accommodate. Myopia is one of the causes of a sharp decline in vision in children aged 8-12 years. Close working distance is one of the most frequently mentioned risk factors for myopia. Head and back posture that bends forward when reading or doing other close-up tasks causes a higher prevalence of myopia. This study was conducted to describe risk factors related to decreased vision in elementary school children. Methods. The study was a descriptive research with a sample of 100 elementary school children taken by simple random sampling. Data was taken using a questionnaire and a Snellen chart. Results. A total of 100 students participated in this study. Most of the participants were aged 11 years old. Based on visual acuity, 20 students have decreased right eye vision, and 21% have decreased left eye vision. Most respondents read every day for 1 hour time as many as 58 (58%) people and had screen time for less than 2 hours (52%). In addition, based on family history, most respondents had parents' glasses (73%). Conclusion. More elementary school children had normal right and left eye vision than those with decreased vision. Most respondents have less screen time and less reading duration.

Comparison of the Observation Errors of Augmented and Spatial Reality Systems

Using 3D technologies such as virtual reality (VR) and augmented reality (AR), has intensified nowadays. The mainstream AR devices in use today are head-mounted displays (HMDs), which, due to specification limitations, may not perform to their full potential within a distance of 1.0 m. The spatial reality display (SRD) is another system that facilitates stereoscopic vision by the naked eye. The recommended working distance is 30.0~75.0 cm. It is crucial to evaluate the observation accuracy within 1.0 m for each device in the medical context. Here, 3D-CG models were created from dental models, and the observation errors of 3D-CG models displayed within 1.0 m by HMD and SRD were verified. The measurement error results showed that the HMD model yielded more significant results than the control model (Model) under some conditions, while the SRD model had the same measurement accuracy as the Model. The measured errors were 0.29~1.92 mm for HMD and 0.02~0.59 mm for SRD. The visual analog scale scores for distinctness were significantly higher for SRD than for HMD. Three-dimensionality did not show any relationship with measurement error. In conclusion, there is a specification limitation for using HMDs within 1.0 m, as shown by the measured values. In the future, it will be essential to consider the characteristics of each device in selecting the use of AR devices. Here, we evaluated the accuracies of 3D-CG models displayed in space using two different systems of AR devices.