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Phase recognition plays an essential role for surgical workflow analysis in computer assisted intervention. Transformer, originally proposed for sequential data modeling in natural language processing, has been successfully applied to surgical phase recognition. Existing works based on transformer mainly focus on modeling attention dependency, without introducing auto-regression. In this work, an Auto-Regressive Surgical Transformer, referred as ARST, is first proposed for on-line surgical phase recognition from laparoscopic videos, modeling the inter-phase correlation implicitly by conditional probability distribution. To reduce inference bias and to enhance phase consistency, we further develop a consistency constraint inference strategy based on auto-regression. We conduct comprehensive validations on a well-known public dataset Cholec80. Experimental results show that our method outperforms the state-of-the-art methods both quantitatively and qualitatively, and achieves an inference rate of 66 frames per second (fps)., Comment: 11 Pages, 3 figures

Supplementary Figure Legends 1-2 from Frequent Truncating Mutation of TFAM Induces Mitochondrial DNA Depletion and Apoptotic Resistance in Microsatellite-Unstable Colorectal Cancer

Supplementary Figure 2 from Frequent Truncating Mutation of TFAM Induces Mitochondrial DNA Depletion and Apoptotic Resistance in Microsatellite-Unstable Colorectal Cancer

The mitochondrial transcription factor A (TFAM) is required for mitochondrial DNA (mtDNA) replication and transcription. Disruption of TFAM results in heart failure and premature aging in mice. But very little is known about the role of TFAM in cancer development. Here, we report the identification of frequent frameshift mutations in the coding mononucleotide repeat of TFAM in sporadic colorectal cancer (CRC) cell lines and in primary tumors with microsatellite instability (MSI), but not in microsatellite stable (MSS) CRC cell lines and tumors. The presence of the TFAM truncating mutation, in CRC cells with MSI, reduced the TFAM protein level in vivo and in vitro and correlated with mtDNA depletion. Furthermore, forced overexpression of wild-type TFAM in RKO cells carrying a TFAM truncating mutation suppressed cell proliferation and inhibited RKO cell-induced xenograft tumor growth. Moreover, these cells showed more susceptibility to cisplatin-induced apoptosis due to an increase of cytochrome b (Cyt b) expression and its release from mitochondria. An interaction assay between TFAM and the heavy-strand promoter (HSP) of mitochondria revealed that mutant TFAM exhibited reduced binding to HSP, leading to reduction in Cyt b transcription. Collectively, these data provide evidence that a high incidence of TFAM truncating mutations leads to mitochondrial copy number reduction and mitochondrial instability, distinguishing most CRC with MSI from MSS CRC. These mutations may play an important role in tumorigenesis and cisplatin-induced apoptotic resistance of most microsatellite-unstable CRCs. Cancer Res; 71(8); 2978–87. ©2011 AACR.

Supplementary Figure 1 from Frequent Truncating Mutation of TFAM Induces Mitochondrial DNA Depletion and Apoptotic Resistance in Microsatellite-Unstable Colorectal Cancer

Saliva blood mixed liquid (SBML) appears in oral surgery, such as scaling and root planning, and it affects surgical vision and causes discomfort to the patient. However, removing SBML, i.e. frequent aspiration of the mixed liquid, is a routine task involving heavy workload and interruption of oral surgery. Therefore, it is valuable to alternate the manual mode by autonomous robotic technique. The robotic system is designed consisting of an RGB-D camera, a manipulator, a disposable oral aspirator. An algorithm is developed for detection of SBML. Path planning method is also addressed for the distal end of the aspirator. A workflow for removing SBML is presented. 95% of the area of the SBML in the oral cavity was removed after liquid aspiration among a group of ten SBML aspiration experiments. This study provides the first result of the autonomous aspirating robot (AAR) for removing SBML in oral surgery, demonstrating that SBML can be removed by the autonomous robot, freeing stomatology surgeon from tedious work.

During a heating experiment, there are two sources of heat that increase the temperature of a coal sample: the heat released by the oxidation reaction of the coal itself, and the heat provided by the experimental system. Here, we propose a method for measuring the thermal effect of oxidation and self-ignition through a reference experiment conducted with a material that is physically similar to coal but does not combust. The reference material used was an aggregate of alumina, fly ash, and concrete, and experiments were conducted on both materials simultaneously. The temperature of the coal sample was obtained under self-heating conditions, and compared with that of the non-combusting material. The relationship of temperature as a function of time for both materials was determined from the data, the comparison of which allowed for the thermal effect of oxidation and coal spontaneous combustion (CSC) to be calculated. The reliability of the thermal effect data obtained by the experiment was verified by chemical bond energy estimation. These results provide theoretical guidance for on-site fire prevention and extinguishing in coal mines, and are important for the further development of the understanding of CSC.

Blue quantum dot (QD) light emitting diode (QLED) developments are far lagging behind the red and green ones as it becomes difficult to balance charge injection and photo stability than the latter. Here, we introduced a combination of a low band energy shell with better surfactants, which largely meet both abovementioned requirements. Our simulation pinpoints that it is the exposed Se on the QD surface, which causes non-radiative relaxations. By adding tributyl phosphine (TBP), which is a good ligand to Se, we recover photoluminescence quantum yield (PLQY) from less than 8.0% up to above 85.0%. The corresponding external quantum efficiency (EQE) of QLEDs increases from 3.1% to 10.1%. This demonstrates that the low bandgap shell with effective surfactant passivation is a promising strategy to enhance QLED performance.

Over the past decade, 3D bioprinting technology has progressed tremendously in the field of tissue engineering in its ability to fabricate individualized biological constructs with precise geometric designability, which offers us the capability to bridge the divergence between engineered tissue constructs and natural tissues. In this work, we first review the current widely used 3D bioprinting approaches, cells, and materials. Next, the updated applications of this technique in tissue engineering, including bone tissue, cartilage tissue, vascular grafts, skin, neural tissue, heart tissue, liver tissue and lung tissue, are briefly introduced. Then, the prominent advantages of 3D bioprinting in tissue engineering are summarized in detail: rapidly prototyping the customized structure, delivering cell-laden materials with high precision in space, and engineering with a highly controllable microenvironment. The current technical deficiencies of 3D bioprinted constructs in terms of mechanical properties and cell behaviors are afterward illustrated, as well as corresponding improvements. Finally, we conclude with future perspectives about 3D bioprinting in tissue engineering.

One of the major difficulties in spinal surgery is the injury of important tissues caused by tissue misclassification, which is the source of surgical complications. Accurate recognization of the tissues is the key to increase safety and effect as well as to reduce the complications of spinal surgery. The study aimed at tissue recognition in the spinal operation area based on electrical impedance and the boundaries of electrical impedance between cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus.Two female white swines with body weight of 40 kg were used to expose cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus under general anesthesia and aseptic conditions. The electrical impedance of these tissues at 12 frequencies (in the range of 10-100 kHz) was measured by electrochemical analyzer with a specially designed probe, at 22.0-25.0°C and 50%-60% humidity. Two types of tissue recognition models - one combines principal component analysis (PCA) and support vector machine (SVM) and the other combines combines SVM and ensemble learning - were constructed, and the boundaries of electrical impedance of the five tissues at 12 frequencies of current were figured out. Linear correlation, two-way ANOVA, and paired T-test were conducted to analyze the relationship between the electrical impedance of different tissues at different frequencies.The results suggest that the differences of electrical impedance mainly came from tissue type (p 0.0001), the electrical impedance of five kinds of tissue was statistically different from each other (p 0.0001). The tissue recognition accuracy of the algorithm based on principal component analysis and support vector machine ranged from 83%-100%, and the overall accuracy was 95.83%. The classification accuracy of the algorithm based on support vector machine and ensemble learning was 100%, and the boundaries of electrical impedance of five tissues at various frequencies were calculated.The electrical impedance of cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus had significant differences in 10-100 kHz frequency. The application of support vector machine realized the accurate tissue recognition in the spinal operation area based on electrical impedance, which is expected to be translated and applied to tissue recognition during spinal surgery.

Surface chemistry mediated direct optical patterning represents an emerging strategy for incorporating colloidal nanocrystals (NCs) in integrated optoelectronic platforms including displays and image sensors. However, the role of photochemistry of crosslinkers and other photoactive species in patterning remains elusive. Here we show the design of nitrene- and carbene-based photocrosslinkers can strongly affect the patterning capabilities and photophysical properties of NCs, especially quantum dots (QDs). Their role beyond physical linkers stems from structure-dictated electronic configuration, energy alignment and associated reaction kinetics and thermodynamics. Patterned QD layers with designed carbene-based crosslinkers fully preserve their photoluminescent and electroluminescent properties. Patterned light emitting diodes (QLEDs) show a maximum external quantum efficiency of ≈12 % and lifetime over 4800 h, among the highest for reported patterned QLEDs. These results would guide the rational design of photoactive species in NC patterning and create new possibilities in the monolithic integration of NCs in high-performance device platforms.

The poly(lactic acid)(PLA)/aliphatic poly(carbonate)(PPC)/polyethylene glycol-polyhedral oligomeric silsesquioxane (PEG-POSS) composites were prepared by reactive melting extrusion. The effect of v...

In micro injection molding, the cavity thickness and surface roughness are the main effects factors of polymer flow in the die designing and affect the quality of molded products significantly. In this study, the effects of cavity thickness and roughness of cavity surface were investigated mainly on polymer flow during molding and on the roughness of molded products. The parts were molded in the cavities with the thickness from 0.05 mm to 0.25 mm and surface roughness from Ra = 46.55 nm to Ra = 462.57 nm, respectively. The filling integrities and roughness replication ratio of molded parts were used to evaluate the statements of polymer flow and microstructure replication during micro injection molding, respectively. The results showed that the filling integrity changing trends in the thinner cavities were obviously different or even opposite to those in the thicker cavities with the changing of cavity surface roughness instead of single trend in the conventional studies. For each cavity surface roughness, the filling integrity showed an upward trend with the increasing cavity thickness. In different cavity thickness, the maximum gap of filling integrity was 23.76 mm, reaching 544.94% from 0.05 mm to 0.25 mm. Additionally, the surface roughness ratio was slightly smaller than one before, reaching the polymer surface roughness limit around Ra = 71.27 nm, which was decided by the nature of the polymer itself. This study proposed the references for the design and fabrication of mold cavities and parts, and saved time and cost in the actual product manufacturing.

A novel self-supported polysaccharide based hydrogel membrane was prepared by adding cellulose nanofiber (CNF) and micron-sized biochar (BC) into sodium alginate (SA) hydrogel with in-situ free water evaporation ("cooking") process and ionic crosslinking, in which the polyethylene glycol (PEG) was used as a pore-forming agent. Herein, CNF can not only enhance the mechanical property of the matrix, but also assist the homogeneous dispersion of BC. As a result, the prepared membrane had a maximum tensile strength of up to 5.69 MPa, which was more than 2-3 times higher than the previously reported self-supported hydrogel membranes. The flux reached 61.5 Lm

The hard rock in the protective coal seam of the Pingdingshan Mine in China is a typical quasi-brittle material exhibiting complex mechanical characteristics. According to available research on the mechanical property, the inelastic deformation and development of damage are considered related with crack initiation and propagation, which are main causes of the material degradation. In the present study, an original experimental investigation on the rock sample of the Pingdingshan coal mine is firstly carried out to obtain the basic mechanical responses in a conventional triaxial compression test. Based on the homogenization method and thermodynamic theory, a damage–friction coupled model is proposed to simulate the non-linear mechanical behavior. In the framework of micromechanics, the hard rock in a protective coal seam is viewed as a heterogeneous material composed of a homogeneous solid matrix and a large number of randomly distributed microcracks, leading to a Representative Elementary Volume (REV), i.e., the matrix–cracks system. By the use of the Mori–Tanaka homogenization scheme, the effective elastic properties of cracked material are obtained within the framework of micromechanics. The expression of free energy on the characteristic unitary is derived by homogenization methods and the pairwise thermodynamic forces associated with the inelastic strain and damage variables. The local stress tensor is decomposed to hydrostatic and deviatoric parts, and the effective tangent stiffness tensor is derived by considering both the plastic yield law and a specific damage criterion. The associated generalized Coulomb friction criterion and damage criterion are introduced to describe the evolution of inelastic strain and damage, respectively. Prepeak and postpeak triaxial response analysis is carried out by coupled damage–friction analysis to obtain analytical expressions for rock strength and to clarify the basic characteristics of the damage resistance function. Finally, by the use of the returning mapping procedure, the proposed damage–friction constitutive model is applied to simulate the deformation of Pingdingshan hard rock in triaxial compression with respect to different confining pressures. It is observed that the numerical results are in good agreement with the experimental data, which can verify the accuracy and show the obvious advantages of the micromechanic-based model.

Motion control strategies of currently available bioprinters are mainly based on the Cartesian coordinate system to perform layer-by-layer stacking of materials along the vertical direction through the axial-aligned horizontal slicing method. The stacked bioprinting strategy that is inconsistent with the growing pattern of natural biological tissues/organs with anisotropic property in some sense, is stimulating new bioprinting techniques such as the stereotactic bioprinting. This paper analytically calculates the forward and inverse kinematics of a four degree-of-freedom (4-DOF) robotic bioprinter prototype developed in our group which is featured with a 3-DOF manipulator and a 1-DOF circular rail for stereotactic bioprinting. Numerical simulations of working space and motion characteristics using MATLAB and V-REP software have validated the performance and feasibility of the developed prototype, which provides a robot-assisted solution reference for the stereotactic bioprinting.

The calibration of binocular infrared camera is a key step to realize the positioning of infrared camera. The existing methods of binocular camera calibration are not suitable for infrared camera, so it is necessary to study the methods of binocular infrared camera calibration and positioning. In this paper, a calibration and positioning method of binocular infrared camera is proposed, and the infrared positioning of two kinds of objects is completed by using this method. Firstly, a special temperature calibration system is used to collect the images for binocular calibration, then the center point detection algorithm and Zhang’s calibration method are used to process the infrared calibration image to obtain the internal and external parameters of the binocular infrared camera. The calibration error is compared with that of binocular visible camera to prove the feasibility of the binocular infrared camera calibration. Secondly, according to the calibrated parameter matrix of the binocular infrared camera, symmetrical circle calibration object detection algorithm and coordinate transformation are carried out for the distortion correction images to achieve infrared positioning of different objects, and the positioning error is obtained. The results show that the calibration method of binocular infrared camera is feasible, and it has more functions than the traditional calibration method.

Anal center detection is of great significance for the diagnosis of anorectal diseases, for accurate anal center detection can help gastrointestinal (GI) robot enter the human body automatically and check the patient’s anal and lower intestinal diseases, which is the first step to realize autonomous diagnosis. However, there is no available result on the anal center detection. In this work, the superpixel method is employed to find the anal center. In the first step, the collected image dataset is expanded through the data augmentation method. In the second step, we use the superpixel segmentation method, a machine learning algorithm, to segment the image by pixels with similar features in the image. Then we determine the region of interest (ROI) based on the threshold and the size of the connected region. After that, the gray barycenter method is used to determine the center of gravity of the ROI i.e., the anal center. The ground-truth anal center is obtained by the average of the anal center coordinates determined by ten anorectal surgeons. By the proposed algorithm, it is found that the ROI detected in 70.59% of the images in the dataset includes the anal center, and the positioning accuracy of the anal center is 88.87% averagely. Thus, the method can provide the anal center for GI robot.

It is easy for human body to contact with objects for a long time to cause fatigue of corresponding parts. How to use robot technology to reduce or eliminate this fatigue in order to improve work efficiency, ensure human health and improve comfort is an important problem in the field of robot. In this paper, combined with the characteristics of animal tissues (puffer’s air bag, etc.), through the application of soft robot related technology, a set of program-controlled active flexible massage system is made. The system is mainly composed of support frame, air bag placement module and electrical system. The system can be freely deformed and combined, soft and comfortable, and has strong expansibility. In addition, we propose a control method to calculate the relationship between the air pressure inside the airbag and the surface tension of the airbag, set four working modes for the system, and measure the air pressure inside the airbag under the four modes. The results show that the proposed control method is feasible and will have a very broad application prospect in medical rehabilitation.

The brittleness of ethyl cellulose (EC) film limited its full applications, and the addition of plasticizers is one of the most common methods to reduce its brittleness. However, the mechanical properties are normally dropped with the addition of plasticizers. Herein, cellulose nanocrystal (CNC) was chosen as a reinforcing agent to improve its mechanical properties. CNC was firstly extracted from the tobacco-stem and then modified by epoxidized soybean oil (ESO) via ring-opening grafting to obtain epoxidized soybean oil grafting CNC (ECNC). The grafting effect was evaluated by FTIR and XPS. After that, the films of ECNC/EC nanocomposites were prepared by the solution-casting method, and their mechanical, thermal and optical properties and fracture morphology were investigated. The results showed that at 4 phr loading of ECNC, the tensile strength of the nanocomposite film was up to 43.7 Mpa (about twice as much as that of the EC film plasticized by ESO), and the elongation at break was not influenced. Moreover, a higher thermal decomposition temperature was achieved for the ECNC/EC films. Besides, owing to the good dispersion, ECNC had no significant impact on the transparency, and the films presented high light transmittance in the visible light region.

The ability to effectively manipulate non-equilibrium ‘hot’ carriers could enable novel schemes for highly efficient energy harvesting and interconversion. In the case of semiconductor materials, realization of such hot-carrier schemes is complicated by extremely fast intraband cooling (picosecond to subpicosecond time scales) due to processes such as phonon emission. Here we show that using magnetically doped colloidal semiconductor quantum dots we can achieve extremely fast rates of spin-exchange processes that allow for ‘uphill’ energy transfer with an energy-gain rate that greatly exceeds the intraband cooling rate. This represents a dramatic departure from the usual situation where energy-dissipation via phonon emission outpaces energy gains due to standard Auger-type energy transfer at least by a factor of three. A highly favourable energy gain/loss rate ratio realized in magnetically doped quantum dots can enable effective schemes for capturing kinetic energy of hot, unrelaxed carriers via processes such as spin-exchange-mediated carrier multiplication and upconversion, hot-carrier extraction and electron photoemission. Subpicosecond spin-exchange Auger interactions realized in manganese-doped quantum dots allow for manipulating hot carriers before their intraband cooling.

It is well known that molecular structure has great influence on the porous structure prepared by breath figures. However, the effect of graft architecture on porous structure from graft copolymer is unclear. Here, the cellulose-based graft copolymers with different graft architectures were synthesized and the highly ordered porous films were facilely prepared by breath figure method. The effects of graft architecture with four different structural parameters on porous structure were systematically investigated. It was found that the pore size increased with the increasing graft chain length, main chain length or molecular weight, while the pore size decreased with the increasing graft density under other similar structural parameters. The shorter main chain and the higher graft density resulted in the smaller pore size. Moreover, the shorter main chain was more beneficial for the formation of highly ordered porous structure than the longer main chain. These results will help to understand the effect of graft architecture on porous structure and regulate pore size by adjusting the graft architecture.

In this paper, we address the problem of fully automatic labeling and segmentation of 3D vertebrae in arbitrary Field-Of-View (FOV) CT images. We propose a deep learning-based two-stage solution to tackle these two problems. More specifically, in the first stage, the challenging vertebra labeling problem is solved via a novel transformers-based 3D object detector that views automatic detection of vertebrae in arbitrary FOV CT scans as a one-to-one set prediction problem. The main components of the new method, called Spine-Transformers, are a one-to-one set based global loss that forces unique predictions and a light-weighted 3D transformer architecture equipped with a skip connection and learnable positional embeddings for encoder and decoder, respectively. We additionally propose an inscribed sphere-based object detector to replace the regular box-based object detector for a better handling of volume orientation variations. Our method reasons about the relationships of different levels of vertebrae and the global volume context to directly infer all vertebrae in parallel. In the second stage, the segmentation of the identified vertebrae and the refinement of the detected centers are then done by training one single multi-task encoder-decoder network for all vertebrae as the network does not need to identify which vertebra it is working on. The two tasks share a common encoder path but with different decoder paths. Comprehensive experiments are conducted on two public datasets and one in-house dataset. The experimental results demonstrate the efficacy of the present approach.

Three-dimensional (3D) bioprinting has been widely applied in the field of biomedical engineering because of its rapidly individualized fabrication and precisely geometric designability. The emerging demand for bioprinted tissues/organs with bio-inspired anisotropic property is stimulating new bioprinting strategies. Stereotactic bioprinting is regarded as a preferable strategy for this purpose, which can perform bioprinting at the target position from any desired orientation in 3D space. In this work, based on the motion characteristics analysis of the stacked bioprinting technologies, mechanism configurations and path planning methods for robotic stereotactic bioprinting were investigated and a prototype system based on the double parallelogram mechanism was introduced in detail. Moreover, the influence of the time dimension on stereotactic bioprinting was discussed. Finally, technical challenges and future trends of stereotactic bioprinting within the field of biomedical engineering were summarized.

Objective: Biopsies are the gold standard for clinical diagnosis. However, a discrepancy between the biopsy sample and target tissue because of misplacement of the biopsy spoon can lead to errors in the diagnosis and subsequent treatment. Thus, correctly determining whether the needle tip is in the tumor is crucial for accurate biopsy results. Methods: A biopsy needle system was designed with a steerable, flexible, and superelastic concentric tube; electrodes to monitor the electrical resistivity; and load cells to monitor the insertion force. The degrees of freedom were analyzed for two working modes: straight-line and deflection. Results: Experimental results showed that the system could perceive the tissue type in online based on the electrical resistivity. In addition, changes in the insertion force indicated transitions between the interfaces of adjacent tissue layers. Conclusion: The two monitoring methods guarantee that the biopsy spoon is at the desired position inside the tumor during an operation. Significance: The proposed biopsy needle system can be integrated into an autonomous robotic biopsy system.

In order to develop better wound dressings, a novel chitosan hydrogel (Cn-Nm gel) was designed and fabricated by using aldehyde-4-arm polyethylene glycol (4r-PEG-CHO) to crosslink the chitosan dissolved in alkaline solution, amino-4-arm polyethylene glycol (4r-PEG-NH2) was chosen as the additive simultaneously. The special dissolution technique and macromolecular crosslinking structure endows the Cn-Nm gels with better performance than that of gels prepared by acid dissolving method with micromolecule crosslinker. First, Cn-Nm gels own strong toughness with 500 kPa tensile strength and 1000% elongation, about 400% swelling ratio and fast water absorption rate. Second, about 300 kPa adhesive strength and strippability between the gels and skin is achieved. More importantly, Cn-Nm gels show nearly 100% antibacterial rate towards Escherichia coli and Staphylococcus aureus. Excellent biocompatibility is also proved by the mouse fibroblasts tests. All of the performance makes this developed chitosan-based gel be the potential candidate as a wound dressing.

The low efficiency and fast degradation of devices from ink-jet printing process hinders the application of quantum dot light emitting diodes on next generation displays. Passivating the trap states caused by both anion and cation under-coordinated sites on the quantum dot surface with proper ligands for ink-jet printing processing reminds a problem. Here we show, by adapting the idea of dual ionic passivation of quantum dots, ink-jet printed quantum dot light emitting diodes with an external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours were reported for the first time. The liquid phase exchange of ligands fulfills the requirements of ink-jet printing processing for possible mass production. And the performance from ink-jet printed quantum dot light emitting diodes truly opens the gate of quantum dot light emitting diode application for industry., Designing efficient and scalable quantum dot LEDs meeting industrial requirements remains a challenge. Here, the authors, by leveraging the liquid phase exchange of d-MX2 ligands, present printed quantum dot LEDs with external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours.

Clinical-oriented robot configuration and data-driven artificial intelligence is evolving robotic orthopedics. This chapter summarizes the harmonious collaboration trend among surgeon–robot–environment interaction in the OR from aspects of the rigid–flexible–soft hybrid mechanical configuration and the environmental structurization, the data-driven trend from aspects of the surgical data science idea, and the artificial intelligence applications in the orthopedics.

Shear thickening of suspensions was generally researched as a macro-perspective, the neglect of microstructure and micro-interactions may deviate the truth. Here, four suspensions were prepared by matching SiO2 microspheres, SiO2-g-PMMA microspheres with oligomeric fluids PEG, PPG, respectively, the rheological behavior of them under the controlled temperature was investigated to figure out the influence of grafted chains on shear thickening. For all suspensions, the reversible shear thickening with significant temperature dependency was observed, the critical shear rate ( γ ˙ ) decreases rapidly and reaches to a balance with the decreased temperature. Under the same media viscosity, the γ ˙ of SiO2/PEG suspensions is higher than that of other suspensions at the lower temperature due to the stronger hydrogen bond interaction between the hydroxyl of microsphere and media. Comparing PEG, using low polar PPG as media raises the γ ˙ of SiO2 suspensions and decreases the γ ˙ of SiO2-g-PMMA suspensions by reason of the changed interaction between microsphere and media, which is also affected by temperature. Moreover, the critical shear stress ( τ c ) of SiO2/PEG suspensions is higher than that of other suspensions in all test temperature region, revealing that the grafted chains weaken the jamming effect. Two models were used to predict τ c , the Wagner’s hard-sphere model predicts the SiO2/PEG suspensions well, Kaldasch’s model based on polymer stabilized colloidal system could fit the SiO2-PMMA/PEG suspensions better.

Ultrasound-based navigation, as a non-invasive and non-radiation image guiding system, is becoming a research focus in minimally invasive navigation surgery, and calibration between an ultrasonic probe and a 3D vision device is one of the key technologies for ultrasonic registration-based navigation. In this paper, a phantom model was designed as a benchmark for calibration. Both iterative closet point (ICP) and coherent point drift (CPD) algorithms are chosen as point cloud registration methods to implement calibration between ultrasonic scanned points and original phantom points to set up the relationship between the ultrasonic probe and the 3D vision device. Because of large topological difference between the ultrasound scanned points and the points from model, ICP algorithm cannot complete the registration, but the CPD algorithm could implement the registration automatically. The average errors of the center point position for each cavity were 1.50, 1.31, and 1.19 mm, respectively, and the average errors of the axis for each cavity were 0.85°, 0.61°, and 0.99°, respectively. Experiment results showed that the average error of calibration by this method satisfies acquirements of most orthopedic surgeries, and the fully automatic implementation of ultrasonic image processing and subsequent calculation is suitable for on-line calibration and verification in surgery.

Due to the huge reserves and great commercial potential of No. A group coal seam, the study on its thermal properties and combustion kinetics have attracted much attention. Via thermogravimetric (TG) analysis, the combustion characteristics and kinetics of No. A 3 coal were studied with three types of coal samples, with the grain diameter less than 200 meshes, 200~100 meshes, 100~60meshes, seperately. Under three characteristic temperatures such as T t , T p and T b , the whole combustion process could be roughly divided into 4 stages. Combined with the T max and T i , these five characteristic temperatures increase with elevating heating rates. The Kissinger-Akahira-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method as reliable methods were used to verify the results of activation energy ( E a ) determined by of model-fitting methods. As complementary, the Coats-Redfern method was used to calculate the pre-exponential factor ( A ) and the correlation coefficient ( R 2 ). According to the evaluation criteria of E a and R 2 , D1 mechanism was the most probable model to depict the combustion kinetics.