Feasibility study on a robot-assisted procedure for tumor localization using needle-rotation force signals

Accurate tumor localization is critical to early-stage cancer diagnosis and therapy. The recent force-guided technique allows to determine the depth of a suspicious tumor on the insertion path, while the spatial localization is still a great challenge. In this paper, a novel force-guided procedure was proposed to identify spatial tumor location using force signals during needle rotation. When there is a harder tumorous tissue around the needle rotation, an abnormal force signal will point to the location of the suspicious tissue. Finite element simulation and phantom experiment were conducted to test the feasibility of the procedure for the tumor localization. The simulation results showed that the harder tumorous tissue made a significant difference on the stress and deformation distributions for the surroundings, changing the needle-rotation force signals when the needle rotated towards the harder tissue. The experimental results indicated that the direction of the tumor location can be identified by the rotation-needle force signals. The intersection point of the two identified directions, derived from force signals of twice needle rotations, determined the tumor location ultimately. Also, parametric sensitivity tests were performed to examine the effective distance of the tumor location centre and the needle insertion point for the tumor localization. This procedure is expected to be used in robot-assisted system for cancer biopsy and brachytherapy

Experimental evidence to understand mechanical causes of retinal detachment following blunt trauma.

PURPOSE: This study aimed to perform an in vitro experiment to simulate retinal detachment caused by blunt impact, and provide experimental evidence to understand mechanical causes of traumatic retinal detachment. METHODS: The experiment was conducted on twenty-two fresh porcine eyes using a bespoke pendulum testing device at two energy levels (0.1J for low energy and 1.0J for high energy). We examined dynamic forces and mechanical responses to the impact, including global deformations, intraocular pressure changes and the energy absorption. Another set of twenty-two eyes underwent pathological examination immediately after being subjected to blunt impact. Twelve additional intact eyes were examined as controls. All pathological sections were scored to indicate whether retinal detachment had occurred. RESULTS: A dynamic variation in intraocular pressure was detected following impact and exhibited an approximate sinusoidal oscillation-attenuation profile. The peaks of impact force were 12.9 ± 1.9 N at low-energy level and 34.8 ± 9.8 N at high-energy level, showing a significant difference (p < 0.001). The positive and negative peaks of intraocular pressure were 149.4 ± 18.9 kPa and -10.9 ± 7.2 kPa at low-energy level, and 274.5 ± 55.2 kPa and -35.7 ± 23.7 kPa at high-energy level, showing significant differences (p < 0.001 for both levels). Retinal detachments were observed in damaged eyes while few detachments were found in control eyes. The occurrence rate of retinal detachment differed significantly (p < 0.05) between the high- and low-energy impact groups. CONCLUSIONS: This study provided experimental evidence that shockwaves produced by blunt trauma break the force equilibrium and lead to the oscillation and negative pressure, which mainly contribute to traumatic retinal detachment

Eye movement characteristics in a mental rotation task presented in virtual reality

IntroductionEye-tracking technology provides a reliable and cost-effective approach to characterize mental representation according to specific patterns. Mental rotation tasks, referring to the mental representation and transformation of visual information, have been widely used to examine visuospatial ability. In these tasks, participants visually perceive three-dimensional (3D) objects and mentally rotate them until they identify whether the paired objects are identical or mirrored. In most studies, 3D objects are presented using two-dimensional (2D) images on a computer screen. Currently, visual neuroscience tends to investigate visual behavior responding to naturalistic stimuli rather than image stimuli. Virtual reality (VR) is an emerging technology used to provide naturalistic stimuli, allowing the investigation of behavioral features in an immersive environment similar to the real world. However, mental rotation tasks using 3D objects in immersive VR have been rarely reported.MethodsHere, we designed a VR mental rotation task using 3D stimuli presented in a head-mounted display (HMD). An eye tracker incorporated into the HMD was used to examine eye movement characteristics during the task synchronically. The stimuli were virtual paired objects oriented at specific angular disparities (0, 60, 120, and 180°). We recruited thirty-three participants who were required to determine whether the paired 3D objects were identical or mirrored.ResultsBehavioral results demonstrated that the response times when comparing mirrored objects were longer than identical objects. Eye-movement results showed that the percent fixation time, the number of within-object fixations, and the number of saccades for the mirrored objects were significantly lower than that for the identical objects, providing further explanations for the behavioral results.DiscussionIn the present work, we examined behavioral and eye movement characteristics during a VR mental rotation task using 3D stimuli. Significant differences were observed in response times and eye movement metrics between identical and mirrored objects. The eye movement data provided further explanation for the behavioral results in the VR mental rotation task

A Novel Synergistic Flame Retardant of Hexaphenoxycyclotriphosphazene for Epoxy Resin

Hexaphenoxycyclotriphosphazene (HPCP) is a common flame retardant for epoxy resin (EP). To improve the thermostability and fire safety of HPCP-containing EP, we combined UiO66-NH2 (a kind of metal-organic frame, MOF) with halloysite nanotubes (HNTs) by hydrothermal reaction to create a novel synergistic flame retardant (H-U) of HPCP for EP. For the EP containing HPCP and H-U, the initial decomposition temperature (T5%) and the temperature of maximum decomposition rate (Tmax) increased by 11 and 17 °C under nitrogen atmosphere compared with those of the EP containing only HPCP. Meanwhile, the EP containing HPCP and H-U exhibited better tensile and flexural properties due to the addition of rigid nanoparticles. Notably, the EP containing HPCP and H-U reached a V-0 rating in UL-94 test and a limited oxygen index (LOI) of 35.2%. However, with the introduction of H-U, the flame retardant performances of EP composites were weakened in the cone calorimeter test, which was probably due to the decreased height of intumescent residual char

Zeolitic Imidazole Framework-90-Based Pesticide Smart-Delivery System with Enhanced Antimicrobial Performance

Multimodal antimicrobial technology is regarded as a promising strategy for controlling plant diseases because it enhances antimicrobial efficacy by blocking multiple pesticide-resistance pathways. In this work, a pH-responsive multimodal antimicrobial system was constructed based on ZIF-90 for the controlled release of kasugamycin (KSM). A series of physicochemical characterizations confirmed the successful fabrication of ZIF-90-KSM. The results indicated that the loading capacity of ZIF-90-KSM for KSM was approximately 6.7% and that the ZIF-90 nanocarriers could protect KSM against photodegradation effectively. The acid pH at the site of disease not only decompose the Schiff base bonds between KSM and ZIF-90, but also completely dissolved the nanocarriers. The simultaneous release of KSM and Zn2+ ions was able to achieve multimodal antimicrobial functions during disease occurs. A bioactivity survey indicated that ZIF-90-KSM had superior fungicidal activity and longer duration against Magnaporthe oryzae than KSM aqueous solution. In addition, the phytotoxicity assessment of ZIF-90-KSM on rice plants did not reveal any adverse effects. Therefore, ZIF-90-KSM prepared by Schiff base reaction has great potential for achieving synergistic antifungal functions and provides an eco-friendly approach to manage rice diseases

Interhemispheric multisensory perception and Bayesian causal inference

Summary: In daily life, our brain needs to eliminate irrelevant signals and integrate relevant signals to facilitate natural interactions with the surrounding. Previous study focused on paradigms without effect of dominant laterality and found that human observers process multisensory signals consistent with Bayesian causal inference (BCI). However, most human activities are of bilateral interaction involved in processing of interhemispheric sensory signals. It remains unclear whether the BCI framework also fits to such activities. Here, we presented a bilateral hand-matching task to understand the causal structure of interhemispheric sensory signals. In this task, participants were asked to match ipsilateral visual or proprioceptive cues with the contralateral hand. Our results suggest that interhemispheric causal inference is most derived from the BCI framework. The interhemispheric perceptual bias may vary strategy models to estimate the contralateral multisensory signals. The findings help to understand how the brain processes the uncertainty information coming from interhemispheric sensory signals