RESUMO
Objective:To explore the clinical application value of preoperative colonoscopic marking by Nd-Fe-B magnet ring to assist laparoscopy.Methods:A total of 51 patients with colorectal tumor who underwent radical laparoscopy from January 2020 to October 2021 at the Department of Gastrointestinal Surgery, Guizhou Provincial People's Hospital were recruited. The patients were marked by Nd-Fe-B magnet ring under endoscopy one day before the operation, another magnet ring was sent into the abdominal cavity during the radical laparoscopy through cannula. The two magnet rings were attracted and clung to each other to orient the lesions. The basic information of patients, location of preoperative marks under endoscopy and laparoscopy conditions were recorded.Results:All 51 Nd-Fe-B magnet rings were successfully located to the position of colorectal tumor and fixed. According to the location of the lesions, there were 15 cases of transverse colon, 12 cases of descending colon, 19 cases of sigmoid colon, and 5 cases of upper rectal segment. According to the lesion type, there were 21 cases of colon cancer, 25 cases of polyp carcinomatosis, and 5 cases of laterally spreading tumors with partial carcinomatosis. There were 5 cases with positive margins after endoscopic mucosal resection and 1 case with positive margin after endoscopic submucosal dissection. All lesions were accurately located during the operation. The marking time was 4.1±1.2 min (3-6 min) before the operation and the localization time was 1.5±1.1 min (0.9-5.3 min) during the operation. All magnet rings were removed from the body by laparoscope. The mean distances between the tumor and the cutting edge of the proximal and distal intestinal segments were 5.5 cm and 6.3 cm, respectively. No complications such as colon mucosal injury, bleeding, intestinal perforation or local inflammatory reactions occurred.Conclusion:Nd-Fe-B magnet ring tracer technique for laparoscopic orientation is simple, fast, accurate and safe with no need for additional equipment or apparatus, which is worthy of clinical application.
RESUMO
Objective To prepare a novel loaded NdFeB and Fe3O4 liquid-solid phase inversion poly (polylactic-co-glycolic acid,PLGA) in situ implant (PLGA 60％ NdFeB-20％ Fe3O4) for ultrasound-guided intratumoral injection,and to investigate its intensity of magnetism and therapeutic efficiency of nude mice bearing MDA-MB-231 breast cancer.Methods PLGA-60 ％ NdFeB-20 ％ Fe3O4 in situ implant was prepared.The microstructure of PLGA-60 ％ NdFeB-20 ％ Fe3O4 was tested with scanning electron microscope (SEM).Magnetometer was used to qualify the intensity of magnetism.For the in vitro assay,60 μl solid PLGA-60％ NdFeB-20％ Fe3O4 implant was put in the center of the electromagnetic induction heating coil.Infrared thermal video of the tubes was simultaneously recorded.The size of 2 cm × 2 cm× 2 cm fresh ex vivo bovine liver was prepared,and then 60 μl PLGA-60％ NdFeB-20％ Fe3O4 was injected into it.Similarly,ex vivo bovine liver was heated by the above intermittent time for 1,2,3,4 minutes,respectively,and the ablation volume was calculated.Finally,nude mice were equally divided into treatment group and control group.Mice in treatment group were discontinuously heated for 3 min after being injected with the above mentioned implant,while CEUS was performed before and after heating to observe the blood perfusion in the tumor.One nude mouse was executed on the next day in each group,then pathological sections and HE staining of tumor tissue were taken,whereas the growth of the remaining nude mice were observed daily.Results SEM showed the implant with rough and porous surface.The magnetism increased with the volume of material.The tube and bovine liver experiments showed that the PLGA-60 ％ NdFeB-20％ Fe3O4 generated heat efficiently.The bovine liver ablation experiment showed that the range of ablation of 60 μl PLGA-60 ％ NdFeB-20％ Fe3O4 implant reached (2.34±0.25)cm3 after 3 min heating.In vivo experiments showed that the tumor tissue began to form a scab on the 2nd day,and the scab began to desquamate on the 20th day.CEUS showed the original predominant enhancement disappeared significantly after the treatment.HE staining proved that cancer cells had coagulative necrosis,whereas tumors in control group became bigger.Conclusion PLGA-60％ NdFeB-20％ Fe3O4 in situ implant can produce obvious thermal effect under high frequency alternating magnetic field,therefore can be effectively ablated with nude mice MDA-MB-231 breast cancer during time interval heating.
RESUMO
STATEMENT OF PROBLEM: Dental magnetic materials have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant but they still have some problems such as low corrosion resistance in oral environments. PURPOSE: To increase the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with TiN and sealed with stainless steels. MATERIALS AND METHODS: Surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with TiN and sealed with stainless steels, and then three kinds of electrochemical corrosion test were performed in 0.9% NaCl solution; potentiodynamic, potentiostatic, and electrochemical impedance test. From this study, corrosion behavior, amount of elements released, mean average surface roughness values, the changing of retention force, and magnetic force values were measured comparing with control group of non-coated magnetic materials. RESULTS: The values of surface roughness of TiN coated Sm-Co and TiN coated Nd-Fe-B based magnetic materials were lower than those of non coated Sm-Co and Nd-Fe-B alloy. From results of potentiodynamic test, the passive current density of TiN coated Sm-Co alloy were smaller than those of TiN coated Nd-Fe-B alloy and non coated alloys in 0.9% NaCl solution. From results of potentiostatic and electrochemical impedance test, the surface stability of the TiN coated Sm-Co alloy was more drastically increased than that of the TiN coated Nd-Fe-B alloy and non-coated alloy. The retention and magnetic force after and before corrosion test did not change in the case of TiN coated magnetic alloy sealed with stainless steel. CONCLUSION: It is considered that the corrosion problem and improvement for surface stability of dental magnetic materials could be solved by ion plating with TiN on the surface of dental magnetic materials and by sealing with stainless steels.
Assuntos
Ligas , Corrosão , Implantes Dentários , Odontologia , Impedância Elétrica , Prótese Maxilofacial , Aço Inoxidável , EstanhoRESUMO
Objective:To investigate the biomechanical effect of magn et ic expansion by a new electronic speckle pattern interferometry. Methods :One fresh human skull of 12 years old with intact suture tissues and pe riodontal membrane was adopted. Magnetic expansion was loaded on the maxilla for 1,5,15,30 and 60 min respectively by magnetic force (NdFeB).Relative informa tion on the maxillary complex was acquired by electronic speckle pattern interfe rometry(ESPI). The deforming fringes was processed by the microcomputer image s ystem and the corresponding out-of plane displacement of the maxillary complex was analyzed. Results:Fringes of the maxillary complex were obs erved on monitor screen when magnetic force was loaded. From 1 min to 30 min-lo ading the fringe density was increasing, but decreased 1 h after loading. There was no fringe in the suture of the skull. Greate deformity was found on the lowe r part of maxilla. Conclusion:Magnetic force of expansion is con centrated in the deep structure of the maxillary complex.
RESUMO
Objective: To test the mechanical properties o f N48 NdFeB magnet.Methods:Samples of N48 NdFeB magnet in the size of 2 mm?3 mm?4 mm were prepared, the residual flux density,coercive force and maximum energy product of the samples were measured, the magnetic density aroun d the magnets,the attractive and repulsive force between two magnets in 0~10 mm air gap were investegated.Results:The residual flux density of t he N48 NdFeB magnet was 1.373 T, coercive force 1 037 A/m and maximum energ y product 368 kJ/m 3.The magnetic density at magnet surface was 0.338 T,it decr eased to 0 at the point that leave magnet surface 20 mm away. The highest attrac tive force was 4.47 N between two magnets, the attractive force was 4.47~0.39 N in 0~5 mm air gap.The highest repulsive force was 2.82 N and the repulsive force was 2.82~0.39 N in 0~5 mm air gap.Conclusion:The magnetic and m echanical properties of the N48 NdFeB magnet can meet the standard of the orthod ontic force.
RESUMO
more efficient tooth movement. The purpose of this study was to evaluate the effect of different static magnetic fields of ND-Fe-B magnet on MC3T3-E1 cells by measuring the alkaline phosphatase activity and observing the amount of stained alkaline phosphatase. For measuring of alkaline phosphatase activity, MC3T3-E1 cells were seeded in first and third row of 12 well culture plate. And Nd-Fe-B magnets were positioned under the first column of first and third row to apply different static magnetic fields(first column:100mT ; second column:4.6mT ; third column:0.5mT ; forth column:0.0mT) to the cells for 7, 13, 19, and 25 days. For staining of alkaline phosphatase, MC3T3-E1 cells were seeded in 100mm culture plates. And Nd-Fe-B magnets were positioned under the corner of plates to apply different static magnetic fields(magnet side:100mT ; the opposite side:0.5mT) to the cells for 7, 13, 19 and 25 days. The results were as follows : 1. ALP activity was increased until day 19 in biochemical determination as well as in histochemical staining. 2. The application of higher magnetic field(100mT) suppressed ALP activity at day 13, 19, 25. On the contrary, the application of the lower magnetic field(4.6mT, 0.5mT) significantly enhanced the ALP activity. 3. Consistent with enzyme assay, histochemical staining of ALP also demonstrated that higher magnetic field(100mT) suppressed ALP activity, lower one(0.5mT) enhanced.