2019 novel coronavirus (2019-nCoV) and 2019-nCoV pneumonia / 中华微生物学和免疫学杂志

In the middle of December in2019, a pneumonia outbreak caused by a new coronavir-us, 2019 novel coronavirus (2019-nCoV), emerged in the populations in Wuhan city of China. The epidem-ic spreads rapidly and has been disseminated throughout the country and to 13 other counties in Asia, Eu-rope, Oceania and North America. To accurately and deeply understand the biological characteristics, epide-miological features and pathogenicity of 2019-nCoV and related immunological characteristics, microbiologi-cal examinations and public protection measure, this study reviewed 2019-nCoV and 2019-nCoV pneumonia based on the newest relevant literatures and the newest version of National Diagnosis and Treatment Scheme of 2019-nCoV pneumonia.

Single Circulating Blast in the Peripheral Blood Film in Normal Individuals and Patients of Non-neoplastic Haematological Disorders and Non-hematological Neoplasms/Disorders- A Study at a Tertiary Care Centre

Introduction: The blasts in the peripheral blood is usuallyassociated with a haematological disorder. Study aimed tosee if a single blast seen in a peripheral blood film of healthyindividuals and patients of non-neoplastic haematologicaldisorders and non-hematological neoplasms/disorders didhave any clinical significance.Material and Methods: The period of study was from 2014to 2018 conducted at a tertiary care hospital. The study wasdone exclusively on Peripheral Blood Films. The films werestained with Leishman stain. An occasional blast was detectedin some healthy subjects and patients of non-neoplastichaematological disorders and non-hematological neoplasms/disorders.Result: The routine smears were analyzed with caution afterthe first case of a patient of Iron Deficiency Anemia revealeda clear-cut Blast. In the period of 4 years from 2014 to 2018,a total of 23 cases of apparently normal individuals or patientswith non neoplastic haematological disorders and nonhematological neoplasms/disorders showed at least 1% on oneseparate occasion.Conclusion: A careful morphological examination in theperipheral smears of few normal individuals and individualswith non neoplastic haematological disorders and nonhematological neoplasms/disorders showed at least 1%Blast on one separate occasion. The cells were clear cutblasts with a large size, fine nuclear chromatin, one to twonucleoli with round to slightly irregular nuclear contours anda mild amount of pale agranular cytoplasm. On thoroughinvestigations of these individuals there was no evidence ofa neoplastic haematological disorder. Therefore a single blastin a peripheral blood seen in a healthy individuals or patientswith benign haematological disorder and non-neoplasticneoplasms/disorders may not always indicate a neoplasticprocess.

Finite Element Analysis on Porous Scaffold with Different Materials to Repair Defects of Rabbit Femur under Immediate Loading / 医用生物力学

Objective To investigate the biomechanical behavior of porous scaffold with different materials (Ti, Ta, PEEK, HA) for repairing rabbit femur defects under immediate loading by three-dimensional finite element analysis (FEA), so as to explore the best porous scaffold material from the perspective of biomechanics. Methods The CBCT combined with software such as Mimics, SolidWorks, Geomagic Studio, ANSYS were used to establish an immediate loading model for the repair of rabbit femur defects with porous scaffolds at different stages of bone healing. The stress and strain distributions on the scaffolds and the surrounding tissues were calculated. Results The maximum equivalent stress of porous scaffold decreased along with the bone healing. In the granulation tissue and fibrous tissue model, the ratio of the maximum equivalent stress to the yield strength of porous scaffold was: HA＞Ta＞PEEK＞Ti. The maximum equivalent stress of the HA porous scaffold was greater than its yield strength. The number of suitable strain elements in tissues around the porous scaffolds was: PEEK＞Ta＞Ti＞HA. The number of potential fracture strain elements in tissues around the porous scaffolds was: HA＞Ta＞PEEK＞Ti. Conclusions The HA porous scaffold could not bear the immediate load and guide bone healing well under immediate loading. The elastic modulus of PEEK porous scaffold was similar to that of bone tissues, which could preferably guide bone healing. PEEK was an ideal porous scaffold material under immediate loading. The research findings provide

Advances in Predicting Fracture Risk Based on Hip Bone Properties / 医用生物力学

With the increasing life span of the population and the increasing proportion of the elderly population, the elderly with osteoporosis are prone to hip fractures, which brings heavy economic burdens to the family and society. The progress in predicting hip fractures from the aspects of the proximal femur geometry, bone mineral density (BMD), fracture risk assessment tool (FRAX) and finite element analysis (FEA) based on computed tomography (CT) imaging was reviewed, in order to understand the influencing factors of fracture risk, improve the accuracy of hip fracture risk prediction for the elderly, detect the high fracture risk group at an early stage, and hence to reduce the occurrence of fractures with appropriate preventing measures, and provide theoretical references for the prevention and treatment of hip fractures.

Combined use of miniscrews and clear aligner for en-mass retraction of maxillary anterior teeth: A finite element analysis / 实用口腔医学杂志

Objective: To evaluate the biomechanical effects of combined use of miniscrew and clear aligner in different kinds of loading condition on the en-mass retraction of maxillary anterior teeth. Methods: 3 D finite element models of the maxillary bone with miniscrews and clear aligner were reconstructed using the method of reverse engineering with CBCT data of an adult patient who had maxillary first premolars extracted. The orthodontic force was loaded by (1) clear aligner, (2) clear aligner and 1. 47 N force of retraction at appliance and (3) clear aligner and 1. 47 N force of retraction at canine, respectively. Results: Under the working condition of (1), (2) and (3), in sagittal direction, the displacement difference of crown and root of the maxillary central incisor was 1. 12 E-02 mm, 1. 29 E-02 mm and 9. 62 E-03 mm respectively, the displacement of the first molar crown was-2. 49 E-02 mm, -2. 09 E-02 mm and-2. 00 E-02 mm respectively; in vertical direction, extrusion of the maxillary central incisor was 1. 77 E-03 mm, 2. 93 E-03 mm and 6. 53 E-04 mm respectively. Conclusion: The working condition (3) is more advantageous to control the torque of incisors and to save the anchorage of posterior teeth, and more effective to control the extrusion of the incisors.

Clinical and imaging features of 13 children with myelin oligodendrocyte glycoprotein antibody encephalomyelitis / 中华实用儿科临床杂志

Objective To investigate the clinical and imaging features of myelin oligodendrocyte glycoprotein antibody(MOG)encephalomyelitis in children. Methods The clinical,laboratory finding,imaging and follow-up data of 13 children with MOG encephalomyelitis(MOG-EM)diagnosed by Children＇s Hospital of Nanjing Medical Univer-sity from December 2016 to December 2018 were retrospectively analyzed. Results Among the 13 children,4 cases were male and 9 cases were female,the median age was 8 years old and 1 month. Symptoms of the first episode included fever,drowsiness in 2 cases,visual acuity in 5 cases,convulsions in 3 cases,urinary retention in 2 cases,and ataxia in 2 cases. Abnormalities were found in 12 cases by the head magnetic resonance imaging(MRI),most of which showed ex-tensive or isolated subcortical white matter lesions,and a few deep gray matter nuclei and brainstem were involved;3 ca-ses of spinal MRI abnormalities,mainly characterized by long segmental transverse myelitis;6 cases optic nerve MRI ab-normalities were found in 6 cases,manifested as disease side optic nerve or optic chiasm abnormal signals;the titer of serum MOG antibody was 1: 10-1: 320 in 13 cases. All children responded well to glucocorticoids and gamma globu-lin,and all symptoms were alleviated after treatment. Two patients had recurrence during the follow-up period,which was characterized by optic neuritis. After azathioprine addition,there was no recurrence after 1 to 2 years of follow-up. Conclusions Children with MOG antibody encephalomyelitis present a decline in visual acuity commonly. The images are mainly acute disseminated encephalomyelitis-like changes,immunosuppressive therapy is effective,generally with a better prognosis.

Resistance ability analysis of improved anchor screw / 上海交通大学学报（医学版）

Objective: To estimate resistance ability of improved anchor screw. Methods: The experiment consisted of two sections: tensile test and finite element analysis (FEA). In the first part, the traditional anchor screw and the improved anchor screw were implanted into the condylar cortical bone, respectively, tensile force was tested by tension machine. In the second part, the three-dimensional finite element model of mandibular condyle was established after the improved anchor screw was implanted, and the FEA was performed by the force applied from three different directions. Results: The FEA results revealed the minimum force of the traditional and improved anchor screws were 48.2 N and 200.0 N, respectively. The tensile strengths of the traditional and improved anchor screws with a 3-0 suture were significantly different (P=0.033). The difference between the traditional anchor screw (3-0 suture) and the improved anchor screw (2-0 suture) were significantly different (P=0.000). Conclusion: Compared with traditional screw, improved anchor screw has better resistance ability, especially combined with 2-0 suture.

The effect of diameter of the screw-access hole on the implant prosthodontic system and surrounding cortical bone-A 3D finite element analysis / 实用口腔医学杂志

Objective: To investigate the stress and stress distribution generated on each component of implant prosthodontic system and surrounding cortical bone when different diameters of screw-access hole (SAH) were prepared on molar crown. Methods: A fimite element(FE) model of partial mandible without first molar was set up, and an Bego implant was insert into it. A total of 5 models of the crown were computer-simulated by varying the diameter (Φ = 0-4 mm) of the SAH. The loading forces were 200 N axially (0°) and 100 N obliquely (45°) respectively on occlusive surface. The FE analysis was performed by computer. Results: Φ ≤3 mm: stress on occlusal surface of crown was almost unchanged and mainly distributed in the loading area. Φ = 4 mm, stress appeared an obvious rise and reached the maximum, the stress concentration under vertical load was changed to the hole margin. In vertical loading, screw could remain at a relatively low stress level when diameter did not exceed 1 mm. No changes on other components was observed. Conclusion: SAH diameter of 1 mm is recommended when a cement-and screw-retained crown is used in posterior region.

Effects of FEA from Polygonum hydropiper L. on Biochemical Indexes and Inflammatory Cytokines in Mice with Endotoxemia Induced by Lipopolysaccharide / 中国中医药信息杂志

Objective To observe the effect of flavonoids ethyl acetate(FEA)from Polygonum hydropiper L.on biochemical indexes and inflammatory cytokines in mice with endotoxemia; To expore the mechanism. Methods Total flavonoids in the whole plant of Polygonum hydropiperum L. were extracted by enzymolysis-ultrasonic coupling method. The FEA part were obtained by extracting and separating, followed with macroporous resin purification and enrichment. The animal model of endotoxemia was established by stimulation of lipopolysaccharide (LPS) in mice. Experimental mice were divided into blank group, model group, FEA high-, medium-, and low-dose groups. Each administration group was given the corresponding concentration of herb liquor. The concentration of malondialdehyde (MDA) and myeloperoxidase (MPO) in intestinal tissue, total antioxidant capacity (T-AOC), superoxide dismutase (T-SOD) activity and glutathione peroxidase (GSH-Px) activity in liver tissue, glutathione (GSH), lysozyme (LZM) and acid phosphatase (ACP) in serum were determined. The contents of tumor necrosis factor-α (TNF-α), interferon (IFN)-α, IFN-γ and interleukin-2 (IL-2) in lung tissue were detected by RT-PCR. Results Compared with blank group,the levels of MDA, MPO in intestinal tissue and serum ACP of model mice were increased, while T-AOC, T-SOD, GSH-Px in liver tissue, serum GSH and LZM levels were decreased; TNF-α in serum, intestinal and liver tissues were increased, the expressions of TNF-α, IFN-α, IFN-γ and IL-2 mRNA in lung tissue were increased. Compared with the model group, the levels of MDA, MPO in intestinal tissue and serum ACP were decreased in all dose of FEA groups;The levels of T-AOC, T-SOD, GSH-Px in liver tissue, serum GSH and LZM of FEA medium and high-dose groups were increased. The content of TNF-α in mice serum, intestinal and liver tissues of all dose of FEA groups were significantly reduced, and the expressions of TNF-α, IFN-α, IFN-γ and IL-2 mRNA in lung tissues were significantly decreased. The pathological morphology of mice lung, ileum and colon tissues of FEA high-dose group were significantly ameliorated than model group. Conclusion FEA can attenuate inflammation injury of endotoxemia mice induced by LPS, which has protective effects for organism.

Progress in technology and application of brain-computer interface / 中国药理学与毒理学杂志

Brain-computer interface (BCI) is a direct communication channel between the brain and a computer or other external devices, providing a new method for human-machine interactions. The main components of BCI include signal acquisition, signal processing and interactive control. Brain signals, such as steady state visually evoked potentials, motion imagery, P300 and hybrid BCI, are usually used in BCI. The signal processing methods are signal preprocessing, feature extraction and classification algorithm. The three classical BCI applications involve the spelling system, motor control system and image searching application. How to improve the information transfer rate, imple-ment real-life applications,and reduce individual differences will the challenges in the future.

Expression and characterization of a keratinase encoding gene gm2886 in Streptomyces pactum ACT12 strain / 生物工程学报

By bioinformatics analysis, a putative keratinase gene gm2886 (Accession number: KY368946) was discovered in the genome of a feather-degrading strain, Streptomyces albidoflavus Fea-10. gm2886 was ligated into integrative Escherichia coli-Streptomyces shuttle vector pSET152 under the promoter PermE and added with C-terminal His-tag. The expression vector was transformed into Streptomyces pactum ACT12 by conjugal transfer and the recombinant protein GM2886-His6 was detected in fermentation broth. GM2886-His6 was purified and characterized. Its size was nearly 36 kDa. GM2886-His6 showed proteolytic activity towards a variety of substrates and could even degrade insoluble substrates, such as azure keratin and chicken feathers. The optimal pH and temperature of GM2886-His6 for proteolysis of casein was pH 10.0 and 50 ℃, respectively. The enzyme activity was inhibited by PMSF, but not EDTA, indicating that GM2886-His6 was a serine proteinase. Our results laid the foundation for the research of the molecular biological mechanism on feather-degrading and for the further utilization of Fea-10.

A finite element analysis of en-mass retraction of maxillary anterior teeth with double keyhole loops / 实用口腔医学杂志

Objective:To evaluate the biomechanical effects of en-mass retraction of maxillary anterior with double keyhole loops in different kinds of loading methods on maxillary anterior teeth.Methods:Three 3D finite element models of the maxillary with double keyhole loops were constructed using MIMICS software with CT data of a male patient who had maxillary first premolars extracted.The orthoclontic force was loaded by ① back winding of the archwire end,② archwire strengthening and ③ archwire strengthening com-bined with successive ligation on the top of the doube keyhole loops,respectively.The initial displacement of maxillary anterior teeth in different loading conditions was analysed with the help of ANSYS software.Results:From the loading condition 1 to 3,on the sagit-tal direction,the displacement difference of crown and root of the maxillary central incisor was reduced from 4.19E -03 mm to -8. 85E -03 mm,which means that the lingual crown tipping movement gradually turn into bodily movement and then to labial tipping crown movement.Meanwhile the displacement of lateral incisor decreased from 7.99E -03 mm to 5.84E -04 mm and that of canine decreased from 9.47E -03 mm to 8.54E -03 mm.Vertical movement of incisors became intrusion from extrusion and intrusion move-ment of canines become more significantly.Conclusion:Torque control of anterior teeth is different in three loading conditions,load-ing by ligation and successive ligation on the top of the double keyhole loops may make the anterior tooth movement as a whole.

Self-assessment of Dental Anxiety and Fear among Dental Students in a Saudi Arabian College.

Introduction: The objective was to determine the levels of anxiety and fear of dental students in relation to dental treatment. Materials and Methods: This was a cross-sectional study and included all dental students registered at a Saudi dental college in 2013/2014. Dental fear and anxiety were evaluated using the Modified Dental Anxiety Scale (MDAS) and Dental Fear survey (DFS). All data was anonymous and confidential. Results: A total 143 students completed the questionnaire (response rate of 88%) of which 67% were female. Females were significantly more anxious compared to males (p<0.01) and there was a positive correlation between dental anxiety and dental fear, patients with dental anxiety were more likely to have dental fear as well. Pre-clinical students reported significantly higher levels of dental fear (p=0.014) and anxiety scores (p=0.008) compared to clinical students. In addition, between 10% and 20% of students reported high levels of dental anxiety and fear respectively and females’ demonstrated higher dental anxiety and fear scores than males. The administration of an anaesthetic injection was the highest cause for both dental fear and anxiety. Conclusion: Female demonstrated higher dental anxiety and dental fear scores than males. In addition pre-clinical students demonstrated higher dental anxiety and dental fear scores than clinical students. The most anxious and fearful item was the anaesthetic injection.

Effects of crown retrieval on implants and the surrounding bone: a finite element analysis

PURPOSE: The aim of this study was to observe stress concentration in the implant, the surrounding bone, and other components under the pull-out force during the crown removal. MATERIALS AND METHODS: Two 3-dimensional models of implant-supported conventional metal ceramic crowns were digitally constructed. One model was designed as a vertically placed implant (3.7 mm × 10 mm) with a straight abutment, and the other model was designed as a 30-degree inclined implant (3.7 mm × 10 mm) with an angled abutment. A pull-out force of 40 N was applied to the crown. The stress values were calculated within the dental implant, the abutment, the abutment screw, and the surrounding bone. RESULTS: The highest stress concentration was observed at the coronal portion of the straight implant (9.29 MPa). The stress concentrations at the cortical bone were lower than at the implants, and maximum stress concentration in bone structure was 1.73 MPa. At the abutment screws, the stress concentration levels were similiar (3.09 MPa and 3.44 MPa), but the localizations were different. The stress at the angled abutment was higher than the stress at the straight abutment. CONCLUSION: The pull-out force, applied during a crown removal, did not show an evident effect in bone structure. The higher stress concentrations were mostly observed at the implant and the abutment collar. In addition, the abutment screw, which is the weakest part of an implant system, also showed stress concentrations. Implant angulation affected the stress concentration levels and localizations. CLINICAL IMPLICATIONS: These results will help clinicians understand the mechanical behavior of cement-retained implant-supported crowns during crown retrieval.

New fixation set-up designed for micro-tensile test / 实用口腔医学杂志

Objective:To introduce a new fixation set-up for micro-tensile test.Methods:Dentin-composite were bonded with AdperTM Single Bond 2 (SB2)and sectioned into stick-shaped specimens.Specimens from each tooth(n =6)were equally divided into Ciucchi's jig and the designed set-up(Control and experimental)groups for micro-tensile bond test according to the utilized fixa-tion set-up.The bonding interface failure mode was examined with field-emission scanning electron microscope (FESEM).Three-dimensional models of the two set-ups and the specimen were developed,stress distribution was analyzed by finite element analysis (FEA).Results:The bond strength(MPa)of experimental and control group was 32.76 ±7.43 and 43.58 ±4.72(P <0.05),the ratio of mixed failure was 28 /36 and 20 /36(P <0.05)respectively.FEA showed that the designed set-up for fixing the sticks pro-vided a uniform stress distribution along the long axis of the specimen.FEA and failure mode analysis confirmed such uniform distri-bution was also concentrated at the bonding interface.Conclusion:The new set-up is feasible for micro-tensile test.

Biomechanical analysis on the fixation of mandibular condyle with sagittal fracture by double plates in 3 ways / 实用口腔医学杂志

Objective:To analyze the biomechanical stress distribution on the sagittal fractured of the mandibular condyle(SFMC) fixed by double plates in 3 different ways.Methods:The fixation finite element models with double straight plates(SS),one straight and one L-form plates(SL),and double L-form plates(LL)were established.The biomechanical stresses on condyle were calculated with finite element analysis.Results:In the model of SS fixation the maximum equivalent stress (MES),maximum total displacement (MTD)and maximum total corner(MTC)of condylar stump were 525.475 MPa,0.902 2 mm and 0.260 1°;MES,MTD,and MTC on fractured free-end were 4.425 MPa,0.882 7 mm and 0.019 9°,respectively.In the model of SL fixation MES,MTD and MTC on condylar stump were 1 135 MPa,0.9367 mm and 0.126 1°;MES,MTD and MTC on fractured free-end were 2.656 MPa,0.887 1 mm and 0.016 9°,respectively.In the model of LL fixation MES,MTD and MTC on condylar stump were 2 208 MPa,0.923 8 mm and 0.172 2°;MES,MTD and MTC on fractured free-end were 14.66 8 MPa,0.876 6 mm and 0.018 1°,respectively.Conclusion:Double L plates fixation is a proper way for SFMC.

The Optimization of Comfortable Earphone Designed by the Method of Semi -parametric / 听力学及言语疾病杂志

Objective To investigate the solutions to the comfort problem caused by traditional batch produc‐tion that cannot satisfy everyone's request .Methods The both objective and subjective evaluations were put forward to the assessment of ear comfort .The accurate data about the pinna was acquired through reverse engineering and extracting key points of the pinna by image detection method .The headphone model was built by the semi-parame‐ter design .Through the FESA study ,headphones - pinna contact pressure was assessed and relevant parameters were improved .Comfort was analyzed by contact pressure .Results The simulation contact pressure was compared before and after optimizing parameters .The results showed that the contact area of the augment cymba conchae could obtain more uniformity pressure .Conclusion The example verification shows this delivers better comfort than traditional one .The research has some reference value for the design and option comfortable headphones .

Finite element analysis on transforaminal lumbar interbody fusion treatment / 医用生物力学

Objective To analyze the clinical feasibility of unilateral transforaminal lumbar interbody fusion (TLIF) for treating lumbar degenerative diseases by finite element method. Methods Based on CT scan data, three-dimensional (3D) finite element models of the normal L3-5 segments under physiological status (intact lumbar model), L4/5 with unilateral pedicle screw fixation plus interbody fusion (unilateral TLIF model) and L4/5 with bilateral pedicle screw fixation plus interbody fusion (bilateral TLIF model) were established by using Mimics, Pro/E, ANSYS software, respectively. Preload of 500 N and load of 10 N•m torque were applied on the superior surface of the L3 segment to simulate 5 physiological activities: body upright, flexion, extension, left lateral bending and right axial rotation. The deformation and stress distributions in vertebral body, vertebral discs, pedicle screw and cage under different loads were then recorded and analyzed to compare mechanical properties of the two fixation methods. Results The deformation of L3-5 segments fixed with unilateral TLIF or bilateral TLIF decreased as compared to the intact lumbar model; the stresses in cage reached the maximum in both unilateral TLIF model and bilateral TLIF model during back extension, meanwhile peak stresses on pedicle screws in unilateral TLIF were significantly higher than those on bilateral TILF model, with the peak stress of 463.39 MPa during back extension. ConclusionsUnilateral TLIF can be selected as a method for treating lumbar degenerative diseases; however, its stability was inferior to bilateral TLIF due to the higher peak stress. Therefore, less stretch exercises may be safe for patients during rehabilitation to avoid surgery failure or pedicle screw fracture.

The effects of non carious cervical lesions - morphology, load type and restoration - on the biomechanical behavior of maxillary premolars: a finite element analysis / OS efeitos das lesões cervicais não cariosas ­ morfologia, tipo de carregamento e restauração - no comportamento biomecânico de pré-molares superiores: análise por elementos finitos

The aim of the present study was to analyze the effects of different types of non-carious cervical lesions (NCCLs) and their morphologies in premolars, restored (or not) with composite resin, on the application three occlusal loadings. The hypothesis was that differing NCCL morphologies, loading types and restoration with composite resin affect stress distribution patterns. A two-dimensional linear Finite Element Analyses (FEA) simulated a healthy tooth model (H) with dental structures including: dentin, pulp, enamel, periodontal ligament, cortical bone, and trabecular bone. Three NCCL morphological models were examined: Mixed (MI), Sauce (SA) and Wedged-shape (WS). All types of lesions were analyzed with and without restoration. The models were considered homogeneous and elastic. In each model three load types: 100N: vertical load (VL), buccal load (BL) and palatine load (PL) were applied. The Maximum Principal Stress values were analyzed. The quantitative analysis of stress (MPa) was identified at five points of the NCCLs according to the morphology of the lesion type: initial point, superior wall, center of lesion, inferior wall and final point. It was found that NCCLs restored with composite resin exhibited stress distribution patterns similar to the healthy tooth model, independent of morphology and load. The Palatine Load was responsible for providing the highest values of accumulated tensions on the NCCL. The highest values of tensile stress on NCCL areas were found in the models without composite resin restoration, which had received PL. It was concluded that the different NCCL morphologies had little effect on stress distribution patterns. The major factors that affected the biomechanical behavior of premolars presenting NCCL were load type and the presence of composite restoration.

O objetivo desse estudo foi analisar a influência de diferentes morfologias de lesões cervicais não cariosas (LCNCs) em pré-molares superiores restaurados ou não com resina composta, aplicando três diferentes carregamentos oclusais. A hipótese é que a morfologia, o tipo de carregamento e a restauração influenciem no padrão de distribuição de tensão. Através do método de elementos finitos, foram simulados modelos bidimensionais, homogêneos, lineares e elásticos. O modelo do dente hígido (H) foi representado com as seguintes estruturas: dentina, polpa, esmalte, ligamento periodontal, osso cortical, osso trabeculado e posteriormente simulou-se três morfologias de LCNCs: Mista(MI), Arredondada (SA) e em forma de Cunha (WS). Todos os tipos de lesão foram analisados com a presença e ausência da restauração. Em cada modelo foram aplicados três diferentes tipos de carregamento, com 100 N cada: carregamento vertical (VL), carregamento vestibular (BL) e carregamento palatino (PL). A análise quantitativa das tensões foi realizada através do critério de Tensão Máxima Principal em cinco regiões de cada LCNC, nos seguintes pontos: ponto inicial, parede superior, centro da lesão, parede inferior e ponto final. Como resultado, as LCNCs restauradas com resina composta apresentaram distribuição de tensão semelhante a do modelo do dente hígido, independente da morfologia e do carregamento. O carregamento palatino foi responsável pelos maiores valores de acúmulo de tensão nas LCNCs. É possível conclui que Os diferentes tipos de morfologia das LCNCs apresentaram pequena influencia no padrão de distribuição de tensão. Os fatores de maior influência no comportamento biomecânico de pré-molares foram o tipo de carregamento e a presença da restauração.

Technique of automatic abdominal aortic aneurysm segmentation and 2D-mesh generation / 医用生物力学

Objective To develop an automatic segmentation and mesh generation technique for abdominal aortic aneurysm (AAA) and to build a 2D numerical analysis model that can be used for finite element analysis (FEA). Methods A method that totally based on morphology processing was developed to segment all the components of the AAA. For each closed curve that obtained, its signed distance function was then calculated. According to the set relationships between each curve, the final signed distance function was calculated. Under the control of this function and an equilibrium relationship, iterated Delaunay algorithms were used until the equilibrium relationship was satisfied or the set conditions were reached. Then the program ended and the finite element model was generated. Results Automatic segmentation of the lumen as well as semiautomatic segmentation of the wall and calcification were achieved. Different parts of the AAA were meshed, and the type and density of the mesh could be controlled. Two finite element models were established for stress analysis: one was the coupling mesh of the thrombus and the wall, and the other was the coupling mesh of the thrombus, the wall and the calcifications. Conclusions An automatic segmentation and mesh generation algorithm with high accuracy has been developed, without any complicated computation or initial curve. The mesh generation algorithm tends to produce high quality meshes and the generation is easy to be controlled by only two parameters. The generated mesh has been verified to be useful in FEA simulation.