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Sample records for clinical crown length

  1. Influence of implant position on clinical crown length and peri-implant soft tissue dimensions at implant-supported single crowns replacing maxillary central incisors

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana;

    2013-01-01

    The aims of the present study were to evaluate the influence of implant position on clinical crown length and marginal soft tissue dimensions at implant-supported single crowns of maxillary central incisors, and to validate the papilla index score (PIS). Twenty-five patients, who had lost one of ...

  2. Evaluation of changes in clinical crown length of lower anterior teeth after treatment with Frankel-2′s appliance

    Directory of Open Access Journals (Sweden)

    Arthur C Vasconcelos

    2014-01-01

    Conclusion: It can be concluded that there is a tendency to increase the clinical crown of lower anterior teeth throughout the years after the mandibular advancement treatment by using functional devices, rejecting the null hypotheisis.

  3. FETAL FOOT LENGTH AND HAND LENGTH: RELATIONSHIP WITH CROWN RUMP LENGTH AND GESTATIONAL AGE

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    Garima

    2015-12-01

    Full Text Available BACKGROUND Estimation of gestational age of fetus is of great medicolegal importance. Multiple parameters of the fetal anatomical measurements are in use. However, gestational age assessment may be difficult in fetus with anencephaly, hydrocephalus, short limb dysplasia, post mortem destruction or in mutilated case. Study of literature suggests that fetal foot has a characteristic pattern of normal growth and the fetal foot shows gradual increase in length relative to the length of the embryo and could be used to estimate gestational age. The purpose of the present study is to determine the accuracy in estimating gestational age using fetal foot and hand length by studying its relation with crown rump length in the foetuses of Manipuri origin. AIMS AND OBJECTIVES 1 To study the relationship between fetal crown rump length and fetal hand and foot length, thereby determining the accuracy in estimating gestational age by a cross-sectional study. MATERIALS AND METHODS A total of 100 formalin fixed fetuses of Manipuri origin, obtained from the Department of Obstetrics and Gynaecology, Regional Institute of Medical Sciences, Imphal, were included in the study, carried out in the Department of Anatomy, from February 2015 to July 2015. The parameters studied were crown rump length, foot length and hand length of fetuses. The data was analysed using SPSS software by regression analysis. Graphs were also plotted to determine pattern of growth and their correlation with crown rump length if any. RESULTS A total of 100 fetuses were studied, of which 43 were females and 57 were males. The mean foot length and hand length progressively increased with increase in crown rump length. Measurements were not significantly different in right or left side or among male and female fetuses. A statistically significant linear relationship was seen between foot length and crown rump length of the fetus (r=0.980, p<0.0001 and hand length and crown rump length of the fetus

  4. Estimation of Gestational Age According to Crown-Rump Length in Nepalese Population: A Comparison with Previously Published Nomograms

    OpenAIRE

    B. Raj Joshi

    2009-01-01

    Background/Objective: This study was performed to construct an institution specific crown-rump length (CRL) nomogram and to compare its ability to predict gestational age with previously published nomograms. "nPatients and Methods: A regression model was developed for estimation of gestational age using CRL measurements of 123 singleton fetuses in the Nepalese population. Measurements were obtained by placing the calipers of the ultrasound machine from the crown to the rump. The appropri...

  5. Crown and root lengths of incisors, canines, and premolars measured by cone-beam computed tomography in patients with malocclusions

    OpenAIRE

    Kim, Seon-Young; Lim, Sung-Hoon; Gang, Sung-Nam; Kim, Hee-Jin

    2013-01-01

    Objective The purposes of this study were to determine the accuracy of crown and root length measurements of premolars using cone-beam computed tomography (CBCT) and to generate reference CBCT-based data on incisor, canine, and premolar lengths in patients with malocclusions. Methods Imaging was performed using a CBCT scanner with a 0.292-mm voxel size and 12-bit grayscale. The CBCT-based length measurements were compared with direct measurements of 94 subsequently extracted premolars without...

  6. Photoelastic Analysis of Fixed Partial Prosthesis Crown Height and Implant Length on Distribution of Stress in Two Dental Implant Systems

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    Evandro Portela Figueirêdo

    2014-01-01

    Full Text Available The aim of this study was to evaluate by photoelastic analysis stress distribution on short and long implants of two dental implant systems with 2-unit implant-supported fixed partial prostheses of 8 mm and 13 mm heights. Sixteen photoelastic models were divided into 4 groups: I: long implant (5×11 mm (Neodent, II: long implant (5×11 mm (Bicon, III: short implant (5×6 mm (Neodent, and IV: short implants (5×6 mm (Bicon. The models were positioned in a circular polariscope associated with a cell load and static axial (0.5 Kgf and nonaxial load (15°, 0.5 Kgf were applied to each group for both prosthetic crown heights. Three-way ANOVA was used to compare the factors implant length, crown height, and implant system (α=0.05. The results showed that implant length was a statistically significant factor for both axial and nonaxial loading. The 13 mm prosthetic crown did not result in statistically significant differences in stress distribution between the implant systems and implant lengths studied, regardless of load type (P>0.05. It can be concluded that short implants showed higher stress levels than long implants. Implant system and length was not relevant factors when prosthetic crown height were increased.

  7. Crown-rump length discordance in the first trimester: a predictor of adverse outcome in twin pregnancies?

    DEFF Research Database (Denmark)

    Johansen, Mathias; Oldenburg, A.; Rosthøj, Susanne;

    2014-01-01

    OBJECTIVES: To evaluate the usefulness of first-trimester crown-rump length (CRL) discordance in predicting adverse outcome in twin pregnancies. METHODS: This retrospective study included a large cohort retrieved from local ultrasound databases at 14 obstetric departments in Denmark, comprising a...

  8. Comparison of Clinical Effects of Au-Pt Based and Ni-Cr Based Porcelain Crowns

    Institute of Scientific and Technical Information of China (English)

    Li-chun Wu; Ye Shi; Teng Ma

    2012-01-01

    Objective To compare the long-term clinical effects of two kinds of crowns and bridges made of porcelain fused to Au-Pt alloy and Ni-Cr alloy.Methods A total of 131 teeth (64 patients) were rehabilitated using porcelain-fused-to-metal crowns,among which 59 were rehabilitated with Au-Pt alloy metal ceramic crown and 72 with Ni-Cr alloy metal ceramic crown.The porcelain fracture,shade,marginal adaptation,gingival discoloration,and gingival status after finishing restoration and 36 months of follow-up were evaluated.Results After 36 months of restoration,porcelain fused to Au-Pt alloy crown showed better clinical effects than porcelain fused to Ni-Cr alloy crown in shade,marginal adaptation,gingival discoloration,as well as gingival status (all P<0.05).Conclusion The Au-Pt alloy ceramic crown is superior to Ni-Cr alloy ceramic crown in long-term clinical effects.

  9. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    Science.gov (United States)

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified. PMID:27198539

  10. [Long-term clinical results with Procera AllCeram full-ceramic crowns].

    Science.gov (United States)

    Galindo, Martha L; Hagmann, Edgar; Marinello, Carlo P; Zitzmann, Nicola U

    2006-01-01

    The aim of this prospective clinical study was to investigate the long-term survival rate of Procera AllCeram full-ceramic crowns, which were fabricated with aluminiumoxide cores. In 50 patients, 155 Procera crowns with a conventional or reduced core (porcelain collar) were placed on natural abutment teeth. 78% of this group (39 patients with 135 crowns) were examined between May and August 2005 according to the modified USPHS-Criteria. These crowns had been in place for a period of one to 92 months (mean 55 months). Almost half of the crowns were located in the molar region, while 28% were premolars and 24% anterior crowns. Due to one crown fracture the cumulative survival rate was 99% after five and seven years. The clinical success was achieved irrespective of the tooth position, tooth vitality, the preparation margin and the cementum medium used (composite resin or glasionomer cement). In addition, survival was neither influenced by the core design with reduced or conventional margin nor by the core thickness, which measured regularly 0.6 mm in the majority of the specimens. Based on the present findings, it can be concluded that Procera AllCeram is a predictable technique for metal-free, esthetic full-ceramic crowns in the anterior and posterior region. PMID:16989114

  11. Maxillary and mandibular anterior crown width/height ratio and its relation to various arch perimeters, arch length, and arch width groups

    Science.gov (United States)

    Shahid, Fazal; Alam, Mohammad Khursheed; Khamis, Mohd Fadhli

    2015-01-01

    Objective: To investigate the maxillary and mandibular anterior crown width/height ratio and its relation to various arch perimeters, arch length, and arch width (intercanine, interpremolar, and intermolar) groups. Materials and Methods: The calculated sample size was 128 subjects. The crown width/height, arch length, arch perimeter, and arch width of the maxilla and mandible were obtained via digital calliper (Mitutoyo, Japan). A total of 4325 variables were measured. The sex differences in the crown width and height were evaluated. Analysis of variance was applied to evaluate the differences between arch length, arch perimeter, and arch width groups. Results: Males had significantly larger mean values for crown width and height than females (P ≤ 0.05) for maxillary and mandibular arches, both. There were no significant differences observed for the crown width/height ratio in various arch length, arch perimeter, and arch width (intercanine, interpremolar, and intermolar) groups (P ≤ 0.05) in maxilla and mandible, both. Conclusions: Our results indicate sexual disparities in the crown width and height. Crown width and height has no significant relation to various arch length, arch perimeter, and arch width groups of maxilla and mandible. Thus, it may be helpful for orthodontic and prosthodontic case investigations and comprehensive management. PMID:26929686

  12. Changes of Root Length and Root-to-Crown Ratio after Apical Surgery

    DEFF Research Database (Denmark)

    von Arx, Thomas; Jensen, Simon S; Bornstein, Michael M

    2015-01-01

    INTRODUCTION: Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assess...

  13. Clinical performance - a reflection of damage accumulation in ceramic dental crowns

    Energy Technology Data Exchange (ETDEWEB)

    Rekow, D.E. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). Dept. of Orthodontics; Thompson, V.P. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). New Jersey Dental School

    2001-07-01

    All-ceramic dental crowns have tremendous appeal for patients - their esthetics nearly match those of natural teeth. Unfortunately, the most esthetic materials are brittle and, consequently, are vulnerable to damage relating to shaping which is exacerbated during cyclic loading during normal chewing. Clinical performance of all-ceramic dental prostheses are directly dependent on damage introduced during fabrication and during fatigue loading associated with function. The accumulation of damage results in unacceptably high failure rates (where failure is defined as a complete fracture requiring replacement of the prosthesis). The relation between shaping damage and fatigue damage on clinical performance of all-ceramic dental crowns was investigated. Materials used commercially for all-ceramic crowns and investigated in this study included a series of different microstructures of machinable glass ceramics (Corning), aluminas and porcelains (Vita Zahnfabrik), and zirconia (Norton). As monolithic materials, strong, tough, fatigue-resistant materials are not sufficiently esthetic for crowns. Crowns fabricated from monolithic esthetic materials have high failure rates. Layering ceramics could provide acceptable strength through management of damage accumulation. (orig.)

  14. Observation of clinical effect of the short crown molars with short-post inlay-crown restoration%短桩钉嵌体冠修复短冠磨牙的临床效果观察

    Institute of Scientific and Technical Information of China (English)

    徐建红; 张蓉

    2012-01-01

    Objective To investigate the indications and restorative applications of a short-post inlay-crown restoration, and to observe the clinical significance of the short crown molar restoration using a short-post inlay-crown. Methods 270 endodontic -treated molars with an occlusogingival distance less than 4mm (i.e. the short crown molar) were randomly divided into the followingthree groups: Group A - short -post inlay -crown restoration; Group B -conventional post inlay-crown restoration; and Group C - inlay-crown restoration with pulp chamber retention. All cases were followed up regularly from two to five years. Results The clinical outcome of 270 molars with inlay -crown restorations was satisfactory. However, gingivitis and/or the lack of edge adhesion was observed in a few cases. The prosthetic effect of Group A and Group B was significantly better than Group C (P0.05). The two groups of inlay-crowns with different lengths of post presented a similar prosthetic effect, and were both better than those in Group C -subjects with inlay-crown restorations with pulp chamber retention. Conclusion The short-post inlay-crown restoration seems to be a simple, affordable and reliable method to restore short crown molars.%目的 探讨短桩钉嵌体冠修复的适应证和修复方法,观察短桩钉嵌体冠修复短冠磨牙的临床意义.方法 对270颗经完善根管治疗的合龈距<4mm的短冠磨牙,随机分为3组,A组:短桩钉嵌体冠修复;B组:常规桩钉预备的嵌体冠修复;C组:对照组不作桩钉预备的利用髓腔固位的嵌体冠修复,每组90颗,定期复查,随访观察2~5年,评价修复效果.结果 270颗磨牙经嵌体冠修复治疗后获得满意效果,个别病例出现牙龈炎和或边缘不密合的情况.A组和B组修复效果明显高于C组,(分别为P<0.01和P<0.05)有显著差异性;A组和B组修复效果比较,(P>0.05)没有显著性差异.表明两组不同桩长度的嵌体冠修复效果并无统计学

  15. Estimation of Gestational Age According to Crown-Rump Length in Nepalese Population: A Comparison with Previously Published Nomograms

    Directory of Open Access Journals (Sweden)

    B. Raj Joshi

    2009-11-01

    Full Text Available Background/Objective: This study was performed to construct an institution specific crown-rump length (CRL nomogram and to compare its ability to predict gestational age with previously published nomograms. "nPatients and Methods: A regression model was developed for estimation of gestational age using CRL measurements of 123 singleton fetuses in the Nepalese population. Measurements were obtained by placing the calipers of the ultrasound machine from the crown to the rump. The appropriateness of previously established CRL nomograms for predicting the gestational age was assessed in the Nepalese population to determine comparability between nomograms. "nResults: CRL corresponds to Robinson's nomogram up to 9 weeks of gestational age. There is a deficiency of 2mm at 10 weeks, 5 mm at 11 weeks and 8 mm at 12 weeks. "nConclusion: CRL measurements are used as a reliable method for estimation of the gestational age as well as a baseline for comparing gestational ages later. CRL corresponds to Robinson's nomogram up to 9 weeks gestational age. There is a deficiency of 2-8 mm from 10-12 weeks gestational age. Difference with the established nomograms may be due to ethnic differences of the fetal development. After 12 weeks, CRL measurement is unreliable due to flexion of the fetus.

  16. Clinical evaluation of the biological width following surgical crown-lengthening procedure: A prospective study

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    Shobha K

    2010-01-01

    Full Text Available Background and Objectives: The purpose of this study was to evaluate the positional changes of the periodontal tissues, particularly the biological width, following surgical crown-lengthening in human subjects. Materials and Methods: A clinical trial study involving 15 patients was carried out for a period of 6 months. Sites were divided into 3 groups: treated (TT sites, adjacent (AD sites and nonadjacent (NAD sites. Free gingival margin [FGM], attachment level, pocket depth, bone level, biological width [BW] were recorded at baseline, 1, 3 and 6 months. Direct bone level after flap reflection was recorded before and after osseous resection at baseline only. Level of osseous crest was lowered based on BW, and supracrestal tooth structure needed using a combination of rotary and hand instruments. Statistical Analysis: Student t test and ANOVA were used. Results: Overall, apical displacement of FGM at TT, AD and NAD sites was statistically significant compared to baseline. The apical displacement of FGM at TT site was more when compared to that at AD and NAD sites at 3 and 6 months. The BW at the TT site was smaller at 1, 3 and 6 months compared to that at baseline. However, at all sites, BW was reestablished to the baseline value at the end of 6 months. Interpretation and Conclusion: The BW at TT sites was reestablished to its original vertical dimension by 6 months. In addition, a consistent 2-mm gain of coronal tooth structure was observed at the 1, 3 and 6-month examinations.

  17. First-trimester screening in pregnancies conceived by assisted reproductive technology: significance of gestational dating by oocyte retrieval or sonographic measurement of crown-rump length

    DEFF Research Database (Denmark)

    Gjerris, A.C.; Loft, A.; Pinborg, A.;

    2008-01-01

    OBJECTIVES: To evaluate, in pregnancies conceived by assisted reproductive technology, whether determination of gestational age (GA) by date of oocyte aspiration (DOA) or crown-rump length (CRL) at first-trimester screening influences the distribution of serum and sonographic markers or the...... performance of first-trimester screening for chromosomal abnormalities. METHODS: GA was calculated using either DOA or CRL at blood sampling and nuchal translucency thickness (NT) measurement in 729 singleton pregnancies conceived by in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI......). Weight-corrected log multiples of the median (MoM) marker distributions specific for IVF pregnancy were established using multiple log regression and compared for DOA- and CRL-based GA calculation. RESULTS: GA determined by CRL was significantly larger, albeit slightly, than was GA determined by DOA...

  18. WITHDRAWN: Clinical fitting of CAD/CAM zirconia single crowns generated from digital intraoral impressions based on active wavefront sampling.

    Science.gov (United States)

    Scotti, Roberto; Cardelli, Paolo; Baldissara, Paolo; Monaco, Carlo

    2011-10-17

    OBJECTIVES: The aim of this clinical trial was to test the accuracy of single all-ceramic zirconia crowns resulting from digital intraoral impressions with active wavefront sampling technology by measuring the marginal and internal fits of the crowns. MATERIALS AND METHODS: Thirty-seven teeth (24 anterior and 13 posterior) in fifteen patients were restored with single zirconia-ceramic crowns (Lava/Lava Ceram; 3M ESPE) generated from a digital intraoral scanner (Lava Chairside Oral Scanner; 3M ESPE). Before definitive insertion, silicone replicas were produced for all 37 crowns. The sample was cut in four sections; each section was evaluated in four points: marginal gap, mid-axial wall, axio-occlusal edge and centro-occlusal. A total of 592 measurements (148 for each evaluation point) was examined using stereomicroscopy with a magnification of 50×. The Mann-Whitney U test was used to evaluate whether there were differences between anterior and posterior values (alpha=0.05). RESULTS: The mean values for each point were: 48.65μm (SD 29.45μm) for the marginal gap, 112.25μm (SD 55.54μm) at the mid-axial wall, 137.81μm (SD 71.31μm) at the axio-occlusal edge of the abutments, and 157.25μm (SD 75.51μm) at the centro-occlusal location. No statistical differences were found between the anterior and posterior group for each point (p-values: P1=0.39; P2=0.38; P3=0.07; P4=0.30). CONCLUSIONS: The marginal and internal fitting values obtained were within literature agreed as clinically acceptable for both anterior and posterior teeth. CLINICAL RELEVANCE: Single crown restorations obtained using digital intraoral impressions based on active wavefront sampling technology presented enough accuracy to be used as an alternative to the conventional impression techniques. PMID:22027653

  19. Lateral cane lengths affect yield components in 'Triple Crown' blackberry on rotating cross-arm trellis and cane training system

    Science.gov (United States)

    Three primocanes of mature ‘Triple Crown’ blackberry plants were trained on the rotating cross-arm trellis (RCA) trellis. By the end of the summer, as many as 30 lateral canes with lengths greater than 3.5 m had developed on three primocanes that had been bent at a 0.50-m height and allowed to exte...

  20. Fabrication of a metal-ceramic crown to fit an existing partial removable dental prosthesis using ceramic pressed to metal technique: a clinical report

    OpenAIRE

    Seo, Jae-Min; Ahn, Seung-Geun

    2014-01-01

    Fabricating a crown to retrofit an existing abutment tooth for a partial removable dental prosthesis (PRDP) is one of the most time-consuming and labor-intensive clinical procedures. In particular, when the patient is concerned with esthetic aspects of restoration, the task of fabricating becomes more daunting. Many techniques for the fabrication of all-metallic or metal-ceramic crowns have been discussed in the literature. This article was aimed to describe a simple fabrication method in whi...

  1. Using a porcelain furnace to debond cement-retained implant crown from the abutment after screw fracture: a clinical report.

    Science.gov (United States)

    Saponaro, Paola C; Heshmati, Reza H; Lee, Damian J

    2015-04-01

    When a screw fracture occurs on a cement-retained, implant-supported restoration, the abutment and restoration are completely separated from the implant's internal connection. Traditionally, an access hole is drilled through the crown to retrieve the broken screw, and the restoration can be placed again as a screw-retained restoration. This clinical report documents a patient whose broken abutment screw was retrieved from the restoration by burning off the cement and separating from the abutment without drilling an access hole. PMID:25316610

  2. Effectiveness of Crown Preparation Assessment Software As an Educational Tool in Simulation Clinic: A Pilot Study.

    Science.gov (United States)

    Tiu, Janine; Cheng, Enxin; Hung, Tzu-Chiao; Yu, Chuan-Chia; Lin, Tony; Schwass, Don; Al-Amleh, Basil

    2016-08-01

    The aim of this pilot study was to evaluate the feasibility of a new tooth preparation assessment software, Preppr, as an educational tool for dental students in achieving optimal parameters for a crown preparation. In February 2015, 30 dental students in their fourth year in a five-year undergraduate dental curriculum in New Zealand were randomly selected from a pool of volunteers (N=40) out of the total class of 85. The participants were placed into one of three groups of ten students each: Group A, the control group, received only written and pictorial instructions; Group B received tutor evaluation and feedback; and Group C performed self-directed learning with the aid of Preppr. Each student was asked to prepare an all-ceramic crown on the lower first molar typodont within three hours and to repeat the exercise three times over the next four weeks. The exercise stipulated a 1 mm finish line dimension and total convergence angles (TOC) between 10 and 20 degrees. Fulfillment of these parameters was taken as an acceptable preparation. The results showed that Group C had the highest percentage of students who achieved minimum finish line dimensions and acceptable TOC angles. Those students also achieved the stipulated requirements earlier than the other groups. This study's findings provide promising data on the feasibility of using Preppr as a self-directed educational tool for students training to prepare dental crowns. PMID:27480712

  3. CAD/CAM ZIRCONIA VS. SLIP-CAST GLASS-INFILTRATED ALUMINA/ZIRCONIA ALL-CERAMIC CROWNS: 2-YEAR RESULTS OF A RANDOMIZED CONTROLLED CLINICAL TRIAL

    OpenAIRE

    Murat Cavit Çehreli; Ali Murat Kökat; Kivanç Akça

    2009-01-01

    The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and p...

  4. 全瓷冠与金属烤瓷冠的临床应用分析%Clinical application on all ceramic crowns and metal ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    代伟; 刘阳

    2015-01-01

    Objective:To investigate the aesthetic effect and the change of periodontal tissue in the restoration of all ceramic crowns and metal ceramic crowns.Methods:108 cases of dental restoration restoration on a total of 168 teeth were selected,they were divided into two groups,with 84 teeth in each group,patients in the observation group were treated with zirconia all ceramic dental restoration,while in the control with Ni Cr alloy porcelain dental restoration.Results:After 1 years,the observation group did not appear cervical margin black line,while 39 teeth in the control group had appear black or marginal discoloration problem. Conclusion:Compared with metal ceramic crowns,all ceramic crowns can reduce the damage to the periodontal tissues,and the appearance and color are excellent,with higher simulation,however,in the crown and bridge it is not as good as the metal porcelain teeth.%目的:探讨全瓷冠与金属烤瓷冠修复的美学效果及牙周组织变化.方法:收治牙齿修复患者 108 例,共计168颗牙,随机分为两组,各84颗,观察组进行二氧化锆全瓷牙修复,对照组进行镍铬合金烤瓷牙修复.结果:1年后,观察组未出现颈缘黑线情况,对照组有39颗出现颈缘发黑、变色问题.结论:全瓷冠相较于金属烤瓷冠用于牙体修复可减少对牙周组织的损伤,而且外观与色泽较为优良,有更高的仿真性,然而在冠桥折断方面不如金属烤瓷牙.

  5. Effects of dry period length on clinical mastitis and other major clinical health disorders

    DEFF Research Database (Denmark)

    Enevoldsen, Carsten; Sørensen, J.T.

    1992-01-01

    Four, 7-, and 10-wk dry periods were randomly assigned to 366 dairy cows in eight herds. A multiple polytomous logistic regression analysis was conducted with the objective to reveal possible important effects of the dry period on the risk of contracting major clinical health disorders. Several...... calving intervals, the risk of occurrence of complications at calving decreased with the length of the dry period. This relation was reversed at longer calving intervals. Dry period lengths of approximately 7 wk appear to be associated with the lowest risk of clinical health disorders, but other factors...... like milk yield at drying off and previous mastitis are much more important predisposing factors....

  6. CAD/CAM ZIRCONIA VS. SLIP-CAST GLASS-INFILTRATED ALUMINA/ZIRCONIA ALL-CERAMIC CROWNS: 2-YEAR RESULTS OF A RANDOMIZED CONTROLLED CLINICAL TRIAL

    Science.gov (United States)

    Çehreli, Murat Cavit; Kökat, Ali Murat; Akça, Kivanç

    2009-01-01

    The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73%) and Cercon® Zirconia (80%) restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66%) than Cercon® Zirconia (26%) restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05). This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone. PMID:19148406

  7. CAD/CAM Zirconia vs. slip-cast glass-infiltrated Alumina/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Murat Cavit Çehreli

    2009-02-01

    Full Text Available The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73% and Cercon® Zirconia (80% restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66% than Cercon® Zirconia (26% restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05. This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone.

  8. Clinical effect of crown lengthening surgery on the residual root and crown%牙冠延长术在残根残冠治疗中的疗效分析

    Institute of Scientific and Technical Information of China (English)

    方道文; 郑炜; 陈青蓝

    2012-01-01

    Objective To explore the clinical effect of treatment methods to restore the residual crown and root. Methods We collected 30 residual crown and roots teeth whose profile are located in the subgingival due to caries and tooth fracture. Then we randomly divided them into two groups, Gingival excision and surgical crown lengthening were applied respectively for repair of anterior gingival surgery treatment. Results The teeth sections were exposed well immediately. The gingival of the two groups had mild edema 1 week after operation , then improved obviously after 2 weeks. In the surgical crown lengthening group the gingival margin was in good shape after 6 weeks, and the gingival was return to normal after 6 months. The periodontal status improved obviously at each time point after operation. Some teeth sections of the gingival excision group were covered by the gingival after 6 weeks to 6 months. The periodontal conditions improved after 2 to 6 weeks,but the gingival sulcus bleeding index increased obviously after 6 monthes. Conclusion Compared to gingival excision , crown lengthening surgery is more advantageous to the residual crown and residual root preservation and restoration, but the choice of indication should be carefully considered.%目的 观察牙冠延长术在残根、残冠保留治疗中的临床效果.方法 收集因龋坏、牙折等所致牙齿断面位于龈下的残根、残冠30颗,随机分成两组,分别应用牙龈切除术及牙冠延长术进行修复前的牙龈外科处理.结果 所有患牙龈下断端在术后即刻均得以暴露.两组术后1周术区龈缘均轻度水肿,2周明显好转.冠延长术组术后6周龈缘外形良好,术后6月基本恢复正常,断端平齐龈缘或位于龈缘冠方;术后各时间点牙周状况均有明显改善.牙龈切除术组术后6周~6月部分患牙龈下断端被牙龈覆盖;术后2~6周牙周状况有所改善,但术后6月龈沟出血指数加重明显.结论 牙冠延长术较牙

  9. Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing

    Institute of Scientific and Technical Information of China (English)

    Rim Hmaidouch; Wolf-Dieter Mu ller; Hans-Christoph Lauer; Paul Weigl

    2014-01-01

    The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n515). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 mm, 10 mm, and 7.5 mm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing;more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.

  10. Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing.

    Science.gov (United States)

    Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

    2014-12-01

    The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces. PMID:25059249

  11. A technique for retrofitting a metal ceramic crown to an attachment-retained removable partial denture: a clinical report.

    Science.gov (United States)

    Uludag, Bulent; Gonuldas, Fehmi; Tokar, Emre; Sahin, Volkan

    2015-02-01

    In dental applications, precision attachments have been used to retain removable partial dentures (RPDs) for several decades. Various types of extracoronal attachments are commonly used in combination with fixed partial dentures and RPDs to achieve retention and stability. Fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention are common reasons for a failed attachment-retained RPD. Another complication of metal ceramic crowns with precision attachment is decementation of the crowns. When fixed components of the attachment-retained RPD fail, the traditional treatment approach requires remaking both the fixed and removable components of the attachment-retained RPD. This technique describes retrofitting of a metal ceramic crown to a resilient attachment-retained RPD. PMID:25066428

  12. Observation for the Clinical Effect of Post-and-Core Crown` Prosthesis to Residual Root and Residual Crown of Quiquagenarian%桩核冠修复中老年残根、残冠的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    王素艳

    2014-01-01

    目的:观察应用玻璃纤维桩、树脂桩核冠修复中老年残根、残冠的临床疗效。方法:对204例中老年患者共计255颗残根、残冠,采用玻璃纤维桩、树脂桩核冠修复和利用。其中,67颗牙用作固定桥修复牙列缺损的基牙,38颗牙用作可摘局部义齿支架修复的基牙。结果:255颗残根、残冠桩核冠修复后经过1~2年的临床随访观察,245颗牙临床疗效可靠,修复体咀嚼功能能满足患者的要求,成功率为96.1%。结论:应用玻璃纤维桩和树脂构建的树脂桩核冠对中老年患者残根、残冠的修复和利用,能达到良好的修复效果,具有广泛的应用前景。%Objective:To observe the clinical effect of quinquagenarian,who constructed by glass fiber post and resin treating residual root and crown.Method:A total of 255 residual roots and crowns for 204 cases of quinquagenarian patients were treated and utilized in use of full crown and resin post and core crown constructed by glass fiber post and resin .Among 255 teeth above,67 were functioning as the abutment of fixed bridge repairing dentition defect.And 38 were as the abutment to remore the surpport of partical denture roots and resdual crowns in use of resin post and core crown. Result:255 residualroots and residual crowns treatmented of resin post and core crown.1-2 years of follow-up clinical observation later,the clinical curatire effect of 245 was relsable and restoration of chewing function could meet the requirements of patients,with the success rate of 96.1%.Conclusion:It is able to achieve favorable result to apply resin post-and-core built by glass fiber post and resin and full crown to restore and utilize the quinquagenarian with residual roots and readual crowns,enjoying a potential and bright prospect.

  13. Marginal and Internal Fit of Conventional Metal-Ceramic and Lithium Disilicate CAD/CAM Crowns.

    Science.gov (United States)

    Nam, Se-Jin; Yoon, Mi-Jung; Kim, Won-Hee; Ryu, Gil-Ju; Bang, Min-Ki; Huh, Jung-Bo

    2015-01-01

    This study aimed to evaluate and compare the marginal and internal gap widths of lithium disilicate computer-aided design / computer-assisted manufacture (LDC) crowns and conventionally produced porcelain-fused-to-metal (PFM) crowns. A convenience sample of 21 patients treated with a single restoration was selected. PFM and LDC crowns were fabricated for each selected abutment tooth, following traditional crown preparation. Silicone replicas were produced, and internal gaps and marginal gaps were measured. Internal gaps were significantly larger for the axial and occlusal surfaces of LDC crowns than for those of PFM crowns (P .05). Both LDC crowns and PFM crowns showed clinically acceptable marginal fit. PMID:26340013

  14. Modeling Crown Biomass for Four Pine Species in China

    Directory of Open Access Journals (Sweden)

    Wen-Tao Zou

    2015-02-01

    Full Text Available To analyze the main variables affecting crown biomass, we measured crown biomass and a number of variables describing tree size, such as stem diameter at breast height (D, tree height (H, crown width (Cw and crown length (Cl, from 754 sample trees of four pine species in China, specifically, Pinus massoniana, P. yunnanensis, P. tabulaeformis and P. elliottii. In addition, we developed individual tree crown biomass equations and compatible branch and needle biomass equations based on one-, two- and multi-variable models using nonlinear mixed-effects modeling and error-in-variable simultaneous equations. The results showed that: (i crown biomass was strongly correlated to D and H, and the new combined variables (D4/H and (D2/H were suitable for modeling two- and multi-variable crown biomass equations, respectively; (ii the four species were ranked as P. yunnanensis, P. massoniana, P. elliottii and P. tabulaeformis from small to large based on estimates from crown biomass equations, and the crown biomass estimate of P. tabulaeformis was about 60% greater than that of P. yunnanensis; (iii the ratio of branch to crown biomass increased with increasing D, and the four species were ranked as P. elliottii, P. tabulaeformis, P. massoniana and P. yunnanensis from small to large by the proportion of the branch to crown biomass; (iv the mean prediction errors (MPE’s of the crown biomass equations for the four species were less than 10%, which could meet precision needs for biomass estimation.

  15. 插销固位一体式金属桩部分冠修复磨牙的临床观察%Clinical observation of molar restoration by bolt fastening integrated metal pile partial crown

    Institute of Scientific and Technical Information of China (English)

    杨勃; 李少萍; 刘名; 梁瑞玲; 刘长虹

    2013-01-01

    Objective To evaluate the clinical effect of molar restoration with short clinical crowns and tooth defect by bolt pile retaining integrated metal pile partial crown.Methods Thiry-eight molars with short clinical crown,tooth defeet,intermaxillary insufficient clearance were repaired by bolt fastening integrated metal pile partial crown.The crowns were examined immediately,1 years,2 years,3 years after the restoration,and the tooth integrity,secondary caries,crown integrity,crown retention,marginal fit and adjacent relation were evaluated.Results Compare the restorations effect of 38 teeth in immediately,1 years,2 years and 3 years after restoration,bolt fastening integrated metal pile partial crown always had excellent retention force,marginal fit,tooth integrity and crown integrity,no secondary caries,and 2 cases of mild food impaction with a ratio of 5.3%.Conclusion The restoration effect of molars with short clinical crowns and tooth defect by bolt fastening integrated metal pile partial crown is excellent and has some practical value in clinical practice.%目的 评价插销固位一体式金属桩部分冠修复牙冠短伴牙体缺损磨牙的临床效果.方法 采用插销固位一体式金属桩部分冠,修复38颗临床牙冠短伴牙体缺损、颌间修复间隙不足的磨牙.修复后即刻、1年、2年、3年进行检查,从牙齿完整性、牙体有无继发龋、修复体完整性、修复体固位、修复体边缘适合性及修复体的邻接关系等进行评价.结果 38颗患牙修复后即刻、1年、2年及3年检查显示,插销固位一体式金属桩部分冠固位良好,牙体及修复体的完整性好,边缘适合性好,没有出现继发龋;有2颗出现轻度食物嵌塞,占5.3%.各项评价指标在修复后即刻、1年、2年、3年的差异均无统计学意义(P>0.05).结论 采用插销固位一体式金属桩部分冠修复临床牙冠短伴牙体缺损的磨牙,修复效果好,在临床上有一定的实用价值.

  16. Clinical application of temporary crown and cement materials: physical properties and biological safety%临时冠材料及黏结材料的临床应用:物理性能与生物安全性

    Institute of Scientific and Technical Information of China (English)

    聂二民; 姜瑞; 张春元; 曾尽娣; 谈济州

    2015-01-01

    背景:临时冠在临床应用较为广泛,临时冠及其黏结材料随着材料科学的发展不断更新,其临床应用、物理学性能及生物安全性方面也越来越优越.目的:综述临时冠及其黏结材料的临床应用现状、物理性能及生物安全性.方法:以"temporary crown,provisional crown,temporary restoration,provisional restoration,interim restoration"为英文检索词,应用计算机检索PubMed数据库中2004年1月至2014年12月发表的相关文章.纳入与临时冠及其黏结材料相关的研究文献,排除重复性研究.结果与结论:通过临床评价和实验研究得出,临时冠材料自身聚合收缩、聚合产热、单体释放等物理特性和细胞毒性、对软组织的刺激性等生物安全性方面是临床要克服的关键问题.临时冠材料和黏结材料在临床上应用广泛,随着新材料筛选和新制作方法的出现其具有巨大的应用前景和较高的临床价值,但在其实验室研究和临床应用的探索过程中,还有许多亟待解决和深入探究的问题.%BACKGROUND:Temporary crown has been used widely in clinic. The physical properties and biological safety of temporary crown and cement materials are more superior along with the development of material science. OBJECTIVE:To summarize clinical application, physical properties and biological safety of the temporary crown and cement materials. METHODS:PubMed database was searched by the key words of "temporary crown, provisional crown, temporary restoration, provisional restoration, interim restoration" in English to retrieve relevant articles published from January 2004 to December 2014. Literatures addressing the temporary crown and cement materials were included, and the repetitive researches were excluded. RESULTS AND CONCLUSION:Through the clinical evaluation and experimental study, the physical properties (polymerization shrinkage, polymerization heat production, polymerization monomer release) and

  17. Paediatric renal length measurements from ultrasound and DMSA scans: does clinical practice reflect theoretical normal values?

    International Nuclear Information System (INIS)

    Full text: Renal length measurement is a routine part of ultrasound examination in children and those results are plotted on a normogram style graph, so that each child's results are compared to a normal range (mean ± 2 S.D.). Renal length measurements from the posterior oblique views of dimercaptosuccinic acid (DMSA) scans in our department have not always correlated well with the ultrasound measurements on the same patients. Renal lengths from the DMSA scans of 120 patients with apparently normal kidneys were recorded and used to generate a normogram of renal length at different ages (0.5-7 years). This DMSA normogram was compared to the ultrasound (US) normogram used in the Paediatric Radiology Department, and it showed slight differences in renal lengths (3-8 mm), but that the US normogram had smaller coefficients of variation (US = 6.6%, NM 8.3%), implying a 'tighter' normal range. 39 of these patients had DMSA and ultrasound measurements of renal length within 3 months, and these were studied first by calculating the mean and CV values for different age groups, and then by plotting individual renal lengths on the appropriate normograms. The measured data produced much greater variability in the ultrasound measurements than the DTPA measurements, and the individual points produced 4/78 (5.1%) abnormal results for DMSA, but 21/78 (26.9%) abnormal results for ultrasound. Thus, in routine clinical use, using patients with apparently normal kidneys, ultrasound was unable to match the 'normal range' set by their current normogram, but the nuclear medicine showed 5.1% of values outside the normal (DMSA) range, which was completely appropriate for a range of ± 2 standard deviations

  18. Clinical common problems after restoration with telescopic crown-retained removable partial dentures%圆锥形套筒冠义齿修复后常见临床问题

    Institute of Scientific and Technical Information of China (English)

    吴琼; 胡伟平

    2015-01-01

    背景:圆锥形套筒冠义齿具有能够自行摘戴、清洁方便、固定义齿异物感小、功能恢复良好等优点,所以近年来应用广泛,但随之也出现了一些问题。目的:综述分析圆锥形套筒冠义齿修复的常见问题并提出对策。方法:应用计算机检索1980至2013年中国知网及PubMed数据库,中文检索词为“圆锥形套筒冠,基牙,临床观察”,英文检索词为“Cone sleeve crown,abutment,Clinical observation”,并且利用主题词补充扩展,广泛查阅近年来有关套筒冠的文献,限定文献语言为英语及中文。结果与结论:圆锥形套筒冠义齿作为修复牙周病伴发牙列缺损的较为理想修复方式,总体来说效果良好,但维持长期稳定的临床效果是套筒冠修复技术面临的主要难题。近年来学者也通过多种方法提高其长期稳定性,例如改变内冠材料效果最为突出,但这些方法在实际临床应用中的远期效果还需要长期观察。圆锥形套筒冠义齿修复后出现的基牙折裂、内冠脱落、基托折裂、牙周问题、固位力降低等为常见症状,通过修理一般不影响套筒冠义齿的继续使用。%BACKGROUND:Telescopic crown-retained removable partial dentures are characterized as pick to wear voluntarily, convenient to clean, smal foreign body sensation of the fixed denture, and good functional recovery, and have been widely used in recent years. However, there are also some problems existing. OBJECTIVE:To review the common problems of the telescopic crown-retained removable partial dentures and to raise the countermeasures. METHODS: A computer-based search of CNKI and PubMed (1980-2013) was performed for relevant articles addressing the telescopic crown using the keywords of “cone sleeve crown, abutment, clinical observation” in Chinese and English, respectively. RESULTS AND CONCLUSION:Telescopic crown-retained removable partial dentures

  19. Marginal Strength of Collarless Metal Ceramic Crown

    Directory of Open Access Journals (Sweden)

    Sikka Swati

    2010-01-01

    fracture strength at margins of metal ceramic crowns cemented to metal tooth analogs. Crowns evaluated with different marginal configurations, shoulder and shoulder bevel with 0 mm, 0.5 mm, 1 mm, and 1.5 mm, were selected. Methods. Maxillary right canine typhodont tooth was prepared to receive a metal ceramic crown with shoulder margin. This was duplicated to get 20 metal teeth analogs. Then the same tooth was reprepared to get shoulder bevel configuration. These crowns were then cemented onmetal teeth analogs and tested for fracture strength atmargin on an Instron testing machine. A progressive compressive load was applied using 6.3 mm diameter rod with crosshead speed of 2.5 mm per minute. Statisticaly analysis was performed with ANOVA, Student's “t” test and “f” test. Results. The fracture strength of collarless metal ceramic crowns under study exceeded the normal biting force. Therefore it can be suggested that collarless metal ceramic crowns with shoulder or shoulder bevel margins up to 1.5 mm framework reduction may be indicated for anteriormetal ceramic restorations. Significance. k Collarless metal ceramic crowns have proved to be successful for anterior fixed restorations. Hence, it may be subjected to more clinical trials.

  20. Efficiency of 2 electronic apex locators on working length determination: A clinical study

    Directory of Open Access Journals (Sweden)

    Sibel Koçak

    2013-01-01

    Full Text Available Aims: The aim of this clinical study was to evaluate the clinical accuracy of two electronic apex locators (EALs. Materials and Methods: A total of 120 patients with 283 roots were randomized into three groups including, traditional radiographic method, EAL (Root ZX mini, and apex locating endodontic motor (VDW Gold for working length (WL determination. Root canals were instrumented to a size ProTaper F3 nickel titanium file. The obturation quality of matched tapered master cone (ProTaper F3 was determined for the accuracy of WL. Statistical Analysis Used: Descriptive statistics were expressed as numbers and percentages. Pearson Chi-square test was used to determine for differences between groups. P < 0.05 was considered statistically significant for all tests. Results: There was no statistically significant difference between the three tested groups ( P = 0.894. Conclusions: The success of both apex locators was similar to the radiographic WL determination technique.

  1. The clinical application of Cerec3D inlay crown in restoring extensively damaged molar%Cerec3D嵌体冠修复后牙大面积牙体缺损的临床应用

    Institute of Scientific and Technical Information of China (English)

    吕晶; 李东霞; 杨捷绯; 邓天政; 柯杰

    2015-01-01

    ObjectiveTo compare the clinical effect of Cerec3D inlay crown with post crown in restoration of extensively damaged molar and provide basis for clinical use in future.MethodsPatients were divided into 2 groups randomly. In group 1, teeth were restored using Cerec 3D inlay crown (inlay crown group). In group 2, teeth were restored using Cerec3D post crown (post crown group). All patients were evaluated based on USPHS measure and gingival index. Statistical analysis with SPSS 15.0 package was carried out.ResultsThere were 53 patients with 63 teeth in inlay crown group, of which 4 patients (5 teeth) were lost. There were 47 patients with 63 teeth in post crown group, of which 4 patients (4 teeth) were lost. No significant differences were observed in the two groups.ConclusionCerec3D inlay crown is suitable for restoring extensively damaged molar, and could perform masticatory function.%目的:本研究利用Cerec3D嵌体冠修复系统修复后牙大面积牙体缺损,并与传统桩冠修复进行临床比较,为今后的临床应用提供研究基础。方法选择行后牙冠修复的患者并随机分为2组。一组采用嵌体冠修复患牙(嵌体冠组),另一组采用桩冠修复患牙(桩冠组),2组进行对比追踪观察,所有入组患者在修复后不同时间点进行改良USPHS检查指标、分级标准和牙龈指数评价。采用SPSS 15.0统计学软件包进行数据统计学分析。结果嵌体冠组53例(63颗患牙),失访4例(5颗患牙);桩冠组47例(63颗患牙),失访4例(4颗患牙)。2组修复后复查,各项指标各时间段组间及组内比较差异均无统计学意义(P>0.05)。结论 Cerec3D嵌体冠适用于后牙大面积牙冠缺损的修复治疗,能够正常行使口颌功能。

  2. Crown Fire Potential

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

  3. Clinical Frailty Scale in an Acute Medicine Unit: a Simple Tool That Predicts Length of Stay

    Science.gov (United States)

    Juma, Salina; Taabazuing, Mary-Margaret; Montero-Odasso, Manuel

    2016-01-01

    Background Frailty is characterized by increased vulnerability to external stressors. When frail older adults are admitted to hospital, they are at increased risk of adverse events including falls, delirium, and disability. The Clinical Frailty Scale (CFS) is a practical and efficient tool for assessing frailty; however, its ability to predict outcomes has not been well studied within the acute medical service. Objective To examine the CFS in elderly patients admitted to the acute medical ward and its association with length of stay. Design Prospective cohort study in an acute care university hospital in London, Ontario, Canada, involving 75 patients over age 65, admitted to the general internal medicine clinical teaching units (CTU). Measurements Patient demographics were collected through chart review, and CFS score was assigned to each patient after brief clinician assessment. The CFS ranges from 1 (very fit) to 9 (terminally ill) based on descriptors and pictographs of activity and functional status. The CFS was collapsed into three categories: non-frail (CFS 1–4), mild-to-moderately frail (CFS 5–6), and severely frail (CFS 7–8). Outcomes of length of stay and 90-day readmission were gathered through the LHSC electronic patient record. Results Severe frailty was associated with longer lengths of stay (Mean = 12.6 ± 12.7 days) compared to mild-to-moderate frailty (mean = 11.2 ± 10.8 days), and non-frailty (mean = 4.1 ± 2.1 days, p = .014). This finding was significant after adjusting for age, sex, and number of medications. Participants with higher frailty scores showed higher readmission rates when compared with those with no frailty (31.2% for severely frail, vs. 34.2% for mild-to-moderately frail vs. 19% for non-frail) although there was no significant difference in the adjusted analysis. Conclusion The CFS helped identify patients that are more likely to have prolonged hospital stays on the acute medical ward. The CFS is an easy to use tool which

  4. Anatomic and functional leg-length inequality: A review and recommendation for clinical decision-making. Part I, anatomic leg-length inequality: prevalence, magnitude, effects and clinical significance

    Directory of Open Access Journals (Sweden)

    Knutson Gary A

    2005-07-01

    Full Text Available Abstract Background Leg-length inequality is most often divided into two groups: anatomic and functional. Part I of this review analyses data collected on anatomic leg-length inequality relative to prevalence, magnitude, effects and clinical significance. Part II examines the functional "short leg" including anatomic-functional relationships, and provides an outline for clinical decision-making. Methods Online database – Medline, CINAHL and MANTIS – and library searches for the time frame of 1970–2005 were done using the term "leg-length inequality". Results and Discussion Using data on leg-length inequality obtained by accurate and reliable x-ray methods, the prevalence of anatomic inequality was found to be 90%, the mean magnitude of anatomic inequality was 5.2 mm (SD 4.1. The evidence suggests that, for most people, anatomic leg-length inequality does not appear to be clinically significant until the magnitude reaches ~ 20 mm (~3/4". Conclusion Anatomic leg-length inequality is near universal, but the average magnitude is small and not likely to be clinically significant.

  5. Clinical Comparison of Root Length Measurements with Electronic Apex Locator and Conventional Radiography in Mandibular Deciduous Teeth

    OpenAIRE

    Eskandarian T; Sahebi S.; Amirabadi F.; Alipour A

    2011-01-01

    Statement of Problem: Success in pulpectomy of deciduous teeth greatly depends on the accuracy of root length measurements which have mostly been done radiographically. However, X-ray risks and patient cooperation have usually been a challenge for the clinicians.Purpose: The clinical comparison of root length measurements with electronic apex locator and conventional radiography in 4-6 year old children's mandibular deciduous teeth was the aim of the present study.Materials and Method: In the...

  6. IPS e.max Press全瓷冠和三单位固定桥的临床评价%Clinical evaluation of IPS e.max Press all-ceramic crowns and three-unit fixed partial dentures

    Institute of Scientific and Technical Information of China (English)

    郭玲; 郑树灿; 罗祖凤; 覃峰; 徐亚娟; 付强

    2009-01-01

    Objective To evaluate the clinical performance of IPS e.max Press all-ceramic crowns and three-unit fixed partial dentures(FPDs)and to investigate the periodontal response to the presence of the restorations.Methods According to the inclusion criteria,19 patients with dental defects or singletooth loss were recruited,including 25 crowns and 6 all-ceramic FPDs.The modified United States Public Health Service criteria were used for follow-up evaluation.Plaque index(PI)and sulcus bleeding index (SBI)were recorded for the ceramic restorations and the control teeth.Results No crown and FPD fractures were observed during the evaluation period.There was no statistically significant difference regarding PLI and SBI scores between restorative teeth and the control teeth.And the difference between different recalled times of PLI and SBI of the restorations was no statistically significant.Conclusion IPS e.max Press crowns and three-unit fixed partial dentures exhibit a satisfactory clinical performance.%目的 探讨在牙科美容修复中应用IPS e.max Press全瓷冠桥的临床疗效及其对基牙牙周组织的影响,总结相关影响因素.方法 采用前瞻性研究的方法,对符合纳入标准的19例患者行IPS e.max Press全瓷冠或全瓷三单位固定桥修复,其中全瓷冠25例,全瓷三单位固定桥6例,参照改良美国公共健康协会标准,对其临床效果进行追踪评价,并记录修复体及对照牙菌斑指数(plague index,PLI)及龈沟出血指数(suleus bleading index,SBI).结果 经过3~12个月的临床追踪观察,无1例IPS e.maxPress修复体松动、折裂、脱落或被替换,修复体组和对照牙组的PLI及SBI的差异无统计学意义,修复体组在不同复诊时间PLI及SBI前后差异无统计学意义.结论 IPS e.max Press全瓷冠桥可获良好的近期临床效果.

  7. 不同材料修复残根、残冠的疗效评价%Evaluation of clinical effecs of the repairing residual roots and residual crowns with different materials

    Institute of Scientific and Technical Information of China (English)

    徐赏

    2001-01-01

    目的:比较银汞合金与复合树脂修复磨牙残根、残冠的疗效。方法:选取因患龋而成残根、残冠的下颌第一磨牙100个,在根管治疗术后,采用钉固位,分别以银汞合金或复合树脂修复,各50个牙,比较其疗效。追踪复查2年后的治疗效果。结果:银汞合金修复者,优45牙(90%),一般4牙(8%),失败1牙(92%)。复合树脂修复者,优40牙(80%),一般6牙(10%),失败4牙(8%)。两者成功率χ2检验,P>0.05。结论:银汞合金修复与复合树脂修复残根、残冠的疗效相差无显著性。%AIM:To compare the clinical effects of repairing the residual roots and residual crowns of molar teeth with silver amalgam or composite resin. METHODS: 100 lower first molars with residual roots or residual crowns by caries were chosen. After root canal therapy, pin retention was adopted, 50 were repaired ones with silver amalgam and 50 ones with composite resin. Then compare their clinical effects for two years. RESULTS: The clinical effects of silver amalgam group showed 45 teeth best or better(90%), 4 teeth good(8%), 1 tooth bad(2%). The clinical effects of composite resin group showed 40 teeth best or better (80%), 6 teeth good(10%), 4 teeth bad(8%) Both successful rates were checked by χ2, P>0.05. CONCLUSION: The clinical effects of repairing residual roots and residual crowns silver amalgam or composite resin are no differece obviously.

  8. 牙冠延长术用于前牙冠修复的牙周指标分析%Periodontal index analysis of crown lengthening surgery for anterior teeth crown restoration

    Institute of Scientific and Technical Information of China (English)

    李隽; 刘晓峰

    2014-01-01

    目的:评价牙周基础治疗及牙冠延长术治疗前牙不良冠修复所致牙周病的临床疗效。方法:选取30例前牙冠修复所致牙周病患者共105颗患牙,均采用牙周基础治疗及牙冠延长术后再行冠修复,观察不同时段临床冠长度的变化,记录各相关牙周指数并进行分析,评估术后全冠修复的临床效果。结果:术后短期内临床冠长度增加效果确切,治疗组术后的各项牙周指数均优于术前(P<0.05),与对照组比较无明显差异(P>0.05),在1年的观察期内保持相对稳定(P>0.05);全冠修复体的固位良好,边缘密合,龈缘与冠缘的位置关系相对稳定。结论:牙周基础治疗及牙冠延长术有利于不良冠修复所致牙周病的治疗,且冠延长术解决了生物学宽度的问题,确保了牙周健康的长期稳定。%Objective:To evaluate the clinical effect of initial therapy and crown lengthening surgery on anterior teeth involved with periodontal disease after crown restored. Method:Initial therapy and crown lengthening surgery were applied to 105 anterior teeth of 30 cases. After treatment all teeth were restored by crowns. At different time we observe changes in clinical crown length,record relevant periodontal index and analyse and evaluate clinical effect of the postoperative crown restoration. Result:Postoperative clinical crown length had obvious short-term effect.The experiment group's postoperative periodontal index were superior to preoperative index(P0.05),and remained relatively stable in one-year observation period (P >0.05).The retention of crown prosthesis was bet-ter,and the margin was fitted well and relatively stable to the margin of gingival. Conclusion:Crown lengthening surgery solved the problem of biologic width. Therefore,right selection of indications,initial therapy,crown lengthening surgery and accurate restoration design contribute to the treatment of periodontal

  9. Clinical observation of the use of mutation type porcelain crown on the anti-bite of lateral incisor%变异式烤瓷冠修复上侧切牙反(牙合)的临床观察

    Institute of Scientific and Technical Information of China (English)

    汤雅; 陈必新

    2012-01-01

    Objective To investigate the clinical design, tooth preparation and restoration effects of the use of mutation type precious metal ceramic crowns on the anti-bite of lateral incisor. Methods We used mutation type precious metal ceramic crown to restore 30(15 cases) anti-bite of lateral incisor. Then after 6 months to 3 years follow-up.we observed the periodontal conditions of the teeth and patients' satisfaction. Results After the restoration of mutation type precious metal ceramic crown, there was no inflammation of the abutment gums.no collapse and crack of porcelain.The appearance of teeth was significantly improved.the patients had no discomfort.and the results were satisfactory. Conclusion Mutation type precious metal ceramic crown on the lateral incisor can be effective in restoring anti-bite of lateral incisor,improving the appearance.and can be used as an alternative to orthodontic treatment.%目的:探讨运用变异式贵金属烤瓷冠修复上侧切牙反(牙合)的临床设计、牙体预备及修复效 果.方法:对30颗(15例)上侧切牙反(牙合)采用变异式贵金属烤瓷冠进行修复,修复后经6个月~3年随访,观察修复后牙周情况和患者满意度 .结果:变异式贵金属烤瓷冠修复后,基牙牙龈无明显炎症,无崩瓷、瓷裂发生,前牙美观程度明显改善,患者无不适,效果满意. 结论:变异式贵金属烤瓷冠可以有效纠正上侧切牙反(牙合),改善美观,可作为正畸治疗的替代手段.

  10. Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

    OpenAIRE

    Kwon, Taek-Ka; Pak, Hyun-Soon; Yang, Jae-Ho; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun; Yeo, In-Sung

    2013-01-01

    PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also ...

  11. Oplevelseskommunikation hos Danish Crown

    OpenAIRE

    Mosbæk, Malene; Ralph Vogelius, Christina; Tranberg-Hansen, Morten Sejer; Møller Bøttiger, Jakob; Axelsen, Lykke Vils

    2011-01-01

    With this report we wish to discover the meaning and use of the phrase experience communication. To investigate experience communication in action, we teamed up with Danish Crown who within recent years has used experience communication as part of their communication strategy. Based on experience communication theory and empirical studies we made an analysis of their campaign “Vi ses i køkkenet”. Our report demonstrates that experiences are a useful way of communicating. Participants co...

  12. Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

    Science.gov (United States)

    Kwon, Taek-Ka; Pak, Hyun-Soon; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun

    2013-01-01

    PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS The mean fracture strengths were as follows: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain. PMID:23755332

  13. Evaluation of bone remodeling around single dental implants of different lengths: a mechanobiological numerical simulation and validation using clinical data.

    Science.gov (United States)

    Sotto-Maior, Bruno Salles; Mercuri, Emílio Graciliano Ferreira; Senna, Plinio Mendes; Assis, Neuza Maria Souza Picorelli; Francischone, Carlos Eduardo; Del Bel Cury, Altair Antoninha

    2016-01-01

    Algorithmic models have been proposed to explain adaptive behavior of bone to loading; however, these models have not been applied to explain the biomechanics of short dental implants. Purpose of present study was to simulate bone remodeling around single implants of different lengths using mechanoregulatory tissue differentiation model derived from the Stanford theory, using finite elements analysis (FEA) and to validate the theoretical prediction with the clinical findings of crestal bone loss. Loading cycles were applied on 7-, 10-, or 13-mm-long dental implants to simulate daily mastication and bone remodeling was assessed by changes in the strain energy density of bone after a 3, 6, and 12 months of function. Moreover, clinical findings of marginal bone loss in 45 patients rehabilitated with same implant designs used in the simulation (n = 15) were computed to validate the theoretical results. FEA analysis showed that although the bone density values reduced over time in the cortical bone for all groups, bone remodeling was independent of implant length. Clinical data showed a similar pattern of bone resorption compared with the data generated from mathematical analyses, independent of implant length. The results of this study showed that the mechanoregulatory tissue model could be employed in monitoring the morphological changes in bone that is subjected to biomechanical loads. In addition, the implant length did not influence the bone remodeling around single dental implants during the first year of loading. PMID:26249362

  14. Cementing porcelain-fused-to-metal crowns.

    Science.gov (United States)

    Vadachkoria, D

    2009-12-01

    The clinical success of fixed prosthodontic restorations can be complex and involve multifaceted procedures. Preparation design, oral hygiene/micro flora, mechanical forces, and restorative materials are only a few of the factors which contribute to overall success. One key factor to success is choosing the proper cement. Popular use of cements for PFM crowns has shifted from zinc phosphate and glass ionomer cements to resin-reinforced glass ionomer, or RRGI, cements. This change has been rapid and profound. Dental cements have always been less than ideal materials, but this is shift to the relatively new RRGI category justified. Resin-reinforced glass ionomer (RRGI) cements appear to be better than zinc phosphate and glass ionomer cements when placing porcelain-to-metal crowns. RRGI cements, such as RelyX Luting, Fuji Plus and Vitremer Luting Cement, satisfy more of the ideal characteristics of PFM cementation than any other previous cement. Expansion of all three cements has not caused any apparent problems with the cements when used with PFM or metal crowns, but these cements, however, should be avoided when cementing all-ceramic crowns. PMID:20090144

  15. Clinical Comparison of Root Length Measurements with Electronic Apex Locator and Conventional Radiography in Mandibular Deciduous Teeth

    Directory of Open Access Journals (Sweden)

    Eskandarian T.

    2011-04-01

    Full Text Available Statement of Problem: Success in pulpectomy of deciduous teeth greatly depends on the accuracy of root length measurements which have mostly been done radiographically. However, X-ray risks and patient cooperation have usually been a challenge for the clinicians.Purpose: The clinical comparison of root length measurements with electronic apex locator and conventional radiography in 4-6 year old children's mandibular deciduous teeth was the aim of the present study.Materials and Method: In the current clinical trial, 15 mandibular molars with 60 canals in 4-6 year old patients who had the treatment plan of pulpectomy were chosen. The measured root lengths with apex locator and parallel technique radiography were evaluated with the same reference point. Data were analyzed using simple linear regression, coefficient of correlation, coefficient of variability and also graphic Bland Altman Plot.Results: The accuracy of electronic apex locator measurements in ±0/5 from apical foramen was 85%. In all cases without considering pulp situation, the difference between the two techniques was not significant.Conclusion: The electronic apex locators are recommended for root length measurements of the deciduous mandibular molars without apical resorption, disregarding the pulp status, especially when initial radiographic films are available.

  16. Marginal Assessment of Crowns by the Aid of Parallel Radiography

    Directory of Open Access Journals (Sweden)

    Farnaz Fattahi

    2015-03-01

    Full Text Available Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm in the vertical (130±20µm and horizontal (90±15µm dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

  17. Leg length discrepancy and femoral offset after total hip arthroplasty : clinical and radiological studies

    OpenAIRE

    Mahmood, Sarwar

    2016-01-01

    Every year, about 1 million patients worldwide and 16000 patients in Sweden undergo total hip arthroplasty (THA). This surgical intervention is considered a successful, safe and cost-effective procedure to regain pain-free mobility and restore hip joint function in patients suffering from severe hip joint disease or trauma. Besides relieving the pain, restoration of biomechanical forces around the hip with appropriate femoral offset (FO), leg length and proper component position and orientati...

  18. The relationship between trinucleotide (GAA) repeat length and clinical features in Friedreich ataxia

    Energy Technology Data Exchange (ETDEWEB)

    Filla, A.; De Michele, G.; Cavalcanti, F. [Federico II Univ., Naples (Italy)] [and others

    1996-09-01

    Friedreich ataxia (FA) is associated with the expansion of a GAA trinucleotide repeat in the first intron of the X25 gene. We found both alleles expanded in 67 FA patients from 48 Italian families. Five patients from three families were compound heterozygotes with expansion on one allele and an isoleucine{r_arrow}phenylalanine change at position 154 on the other one. We found neither expansions nor point mutations in three patients. The length of FA alleles ranged from 201 to 1,186 repeat units, with no overlap with the normal range, and showed a negatively skewed distribution with a peak between 800 and 1,000 repeats. The FA repeat showed meiotic instability with a median variation of 150 repeats. The lengths of both larger and smaller alleles in each patient inversely correlated with age at onset of the disorder. Smaller alleles showed the best correlation, accounting for {approximately}50% of the variation of age at onset. Mean allele length was significantly higher in patients with diabetes and in those with cardiomyopathy. 16 refs., 3 figs., 1 tab.

  19. 氧化铝渗透陶瓷全冠色差可接受性的临床评价%Clinical assessment of acceptability of shade mismatch of infiltrated alumina ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    董正杰; 徐侃

    2011-01-01

    PURPOSE: To measure and evaluate the acceptability of shade mismatch of infiltrated alumina ceramic crowns directly in clinic. METHODS: Ten cases with restoration of hot casting alumina ceramic crown were collected in clinic. L*, a*, b*, C, H, ΔE values of hot casting alumina ceramic crowns and corresponding natural teeth in natural light were surveyed and calculated,then analyzed with CIE1976L*a*h* color system, digital photography and Photoshop CS2.All statistical analyses and calculations were completed in paired t test with SAS6.12 software package. RESULTS: In cervical 1/3 region, significant statistical difference in lightness, a*, hue angle parameter value between alumina allceramic crown and natural tooth (P<0.01) was found; in middle 1/3 region, significant difference in a*, b*, saturation parameter value (P<0.01) existed; in incisory 1/3 region, the parameters had no significant difference (P>0.05). To parameter ΔE, there was significant difference in every region, but it was in the acceptable range. CONCLUSIONS: The acceptability of shade mismatch is about 6 Δ E units, we can analyse the color difference between the restoration and natural teeth directly in clinic through symmetry of central incisor.%目的:测量和评价氧化铝渗透陶瓷全冠临床色差的可接受性.方法:收集10个氧化铝渗透陶瓷全冠修复病例,应用CIE1976L*a*b*颜色系统,采用数码摄影和Photoshop软件电腩处理技术,在自然光线下,对各全瓷冠及其相对称的天然牙测量、分析,计算L、a、b、C、H和△E各参数值.所得数据运用SAS6.12软件包进行配对t检验.结果:在颈1/3区域,氧化铝渗透陶瓷全冠和天然牙在明度、a色品值、色相角上有显著差异;在中1/3区域,参数a、b色品值和饱和度有显著差异:在切1/3区域,各参数值均无显著差异.参数△E值在各区域都有显著差异,但其差异值在患者可接受范围内.结论:氧化铝渗透陶瓷全冠色差可接受

  20. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Stamoulis, Catherine; Bixby, Sarah D.; Breen, Micheal A.; Connolly, Susan A.; Kleinman, Paul K. [Boston Children' s Hospital, Harvard Medical School, Department of Radiology, Boston, MA (United States)

    2016-03-15

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  1. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    International Nuclear Information System (INIS)

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  2. 全冠与高嵌体修复根管治疗后牙牙体缺损的临床观察%Clinical observation of root canal treatment after tooth body defection crown Onlays

    Institute of Scientific and Technical Information of China (English)

    韩风雷

    2014-01-01

    目的:观察磨牙经过根管治疗后对其运用全冠、高嵌体修复的效果。方法:选取经过某门诊完善根管治疗的磨牙240例分两组,每组120例,A组行全冠修复,B组行高嵌体修复,观察其修复的效果。结果:通过对A组120例磨牙的嵌体,B组120例磨牙全冠修复后2~5年随访观察,A组107颗修复成功,咀嚼功能恢复良好,6颗牙出现不同程度的松动,5颗出现牙龈萎缩,2颗因牙周炎拔除。 B组109颗修复成功,咀嚼功能恢复良好,边缘密合,仅5颗牙出现不同程度松动,4颗出现牙龈萎缩,2颗因牙周炎拔除。结论:根管治疗后全冠修复或高嵌体修复在临床上效果无明显差异,但鉴于高嵌体磨除牙体组织少,不破坏患牙与邻牙邻接关系,不涉及牙龈组织的关系等诸多优点,临床应更多推广高嵌体。%Objective:To observe the molars after root canal treatment using crowns, onlays its effects. Methods:after my root canal therapy outpatient perfect teeth 240 cases divided into two groups, 120 cases in each group, a set of rows crowns, onlays a row repair, repair observed effects. Results:A group of 120 cases of molar inlays, group B 120 cases molar crown after 2 to 5 years of follow-up observation repair, A group of 107 successful repair, restore chewing function well, six different degrees of loose teeth, 5 gum recession occurs, two pull out due to periodontitis. Group B 109 teeth repair is successful, chewing can be a good recovery, edge seal, only five different degrees loose teeth, gum recession occurs four, two pull out due to periodontitis.Conclusion:The root canal treatment crowns or on-lays on the clinical effect was no significant difference, but given onlays wear less tooth structure removed, does not destroy the teeth adjacent relationship with adjacent teeth, gum tissue does not involve many advantages relations, which is worthy of more clinical promotion.

  3. 纤维桩用于后牙桩核冠修复的临床疗效评价%Evaluation of the clinical effects of fiber post on the restoration of post core crown in posterior teeth

    Institute of Scientific and Technical Information of China (English)

    贾燕; 李萍

    2015-01-01

    目的 探讨纤维桩用于后牙牙体严重缺损桩核冠修复的临床效果.方法 随机选取2010年1月至2011年4月我院牙科门诊接诊的84例后牙桩核冠修复患者,采用随机数字表法,将患者分成实验组和对照组各42例,实验组采用纤维桩核冠修复,对照组采用金属桩核冠修复,对修复后第6个月和12个月的修复效果采用X线根尖片进行复查评估,对2组的临床效果进行统计学分析.结果 2组在修复后6个月和12个月的修复体边缘适合性、解剖外形、表面、X线根尖评估均为"好",其中实验组在2个时间点分别有1例出现牙龈健康状况评估为"可接受",第12个月有1例评估为"不可接受".实验组的修复成功率为95.83%,仅有2例出现桩冠松动或脱落,对照组修复成功率为81.81%,实验组的修复成功率显著高于对照组(P<0.05).结论 纤维桩用于后牙牙体严重缺损桩核冠修复的临床效果显著优于金属桩核,修复成功率更高,值得临床应用推广.%Objective To explore the clinical effects of fiber post on the restoration of posterior teeth with severe defects. Methods 84 cases of posterior teeth with severe defects randomly selected from January 2010 to 2011 April in our hospital out-patient admissions, were randomly divided into experimental group and control group with 42 cases in each group. The experimental group was restored with fiber post core crown, and the control group was restored with metal post core crown. The clinical effects of two kinds of fiber posts were compared by statistical analysis. At 6 months and 12 months after restoration, the clinical effects were assessed by X-ray peri-apical films. Results The marginal fit, anatomical shape, surface and periapical lesion by X-ray measurement of two groups were"good". In the experimental group, both at 6 months and 12 months, there was respectively 1 case evaluated by gingival health assessment as"acceptable", while there was 1 case

  4. Effect of interprofessional clinical education programme length on students' attitudes towards teamwork.

    Science.gov (United States)

    Renschler, Lauren; Rhodes, Darson; Cox, Carol

    2016-05-01

    This article reports on a study involving a range of health professions students who participated in similar one-semester (short) or two-semester (long) interprofessional clinical education programmes that focused on clinical assessment of senior citizens living independently in the community. Students' attitudes towards teamwork skills and perceptions of their own teamwork skills both before and after the programmes were assessed using two validated scales. Osteopathic medical student participants reported no significant changes in attitudes towards interprofessional healthcare teamwork skills or their perceptions of their own interprofessional teamwork skills after either the one- or two-semester programmes. For athletic training, speech-language pathology, exercise sciences, public health, and nursing students, though, attitudes towards teamwork skills significantly improved (p attitude change, but with a significant difference between medical as compared to nursing, allied health, and public health students. PMID:27152538

  5. Aesthetic treatment on anterior teeth crown fracture caused by dental trauma

    OpenAIRE

    Nanik Zubaidah

    2012-01-01

    Background: Complicated crown fracture is a tooth fracture that involve enamel, dentine and pulp. The incidence of complicated crown fracture ranges from 2% to 13% of all dental injuries and the most commonly involved teeth are the maxillary central incisors. Various treatment modalities are available depending on the clinical, physiological and radiographic examination of the involved teeth. Purpose: The aim of this case report is to present the management of crown fractures with pulpal expo...

  6. Delineation of Campylobacter concisus genomospecies by amplified fragment length polymorphism analysis and correlation of results with clinical data

    DEFF Research Database (Denmark)

    Aabenhus, R.; On, Stephen L.W.; Siemer, Berit L.; Permin, H.; Andersen, L.P.

    2005-01-01

    phenotypically indistinguishable but genetically distinct taxa (i.e., genornospecies) that may vary in pathogenicity. We examined 62 C concisus strains by amplified fragment length polymorphism (AFLP) profiling and correlated the results with clinical data. All C. concisus strains gave unique AFLP profiles, and...... numerical analysis of these data distributed the strains among four clusters. The clustering was of taxonomic significance: two clusters contained, respectively, the type strain (of oral origin) and a reference strain (from diarrhea) of each of the known genomospecies. Genomospecies 2 strains were more...

  7. Profile根管器械治疗后牙残根残冠的观察%Clinical observation of Profile machine with root canal instrumentation in treatment of posterior residual root and crown

    Institute of Scientific and Technical Information of China (English)

    陈永吉; 郭俊兵; 贺维; 毛敏; 柴红波

    2011-01-01

    目的 比较Profile机用根管器械和传统根管器械进行后牙残根残冠根管治疗的疗效,为临床治疗此类牙体疾病提供参考.方法 临床后牙残根残冠100例,随机数字表法分为治疗组(A组)50例采用Profil.机用根管器械机扩,对照组(B组)50例采用手用器械(K锉)手扩.比较两组间临床成功率、治疗时间和患者满意度.结果 对于弯曲根管,Profile机扩比手扩成功率高;对于普通根管,Profile机扩与手扩成功率无差别.但用Profile机扩技术比K锉手扩降低了患者的疼痛程度,缩短了治疗时间.结论 使用Profile机用根管器械机扩技术治疗后牙残根残冠,特别是对于弯曲根管,能够满足临床需要;同时可以提高患者满意度和缩短治疗时间.%Objective To compare the effect of Profile machine of endodontic instruments and traditional root canal instruments for residual root and crown of posterior tooth root canal treatment, for the clinical treatment of this kind of dental disease to provide reference. Methods Clinical posterior residual crown and root of 100 cases were randomly divided into two groups. Treatment group (A group) were 50 cases of teeth, including root canal curvature in 28 cases, using Profile machine root canal instruments machine. Control group(B group) were 50 cases, including 26 cases of root canal curvature , with hand instruments ( K file) hand extended, statistical its clinical success rate, treatment time, and patient satisfaction. Results For the curved root canal, Profile machine expansion endodontic instruments than hand instruments(K filing) handextended high success rate; For normal root canal, the use of machine Profile machine expansion endodontic instruments and hand instruments ( K filing) hand no difference in success rate of expansion. But the machine used Profile root canal instruments machine expansion technology than hand instruments(K file) hand extended reduces patient pain, shorten the treatment

  8. Establishment of a Method to Measure Length of the Ulnar Nerve and Standardize F-wave Values in Clinically Normal Beagles

    OpenAIRE

    HIRASAWA, Shun; Shimizu, Miki; MARUI, Yuumi; KISHIMOTO, Miori; OKUNO, Seiichi

    2014-01-01

    We designed a new method of measuring the length of the ulnar nerve and determining standard values for F-wave parameters of the ulnar nerve in clinically normal beagles. Nerve length must be precisely measured to determine F-wave latency and conduction velocity. The length of the forelimb has served as the length of the ulnar nerve for F-wave assessments, but report indicates that F-wave latency is proportional to the length of the pathway traveled by nerve impulses. Therefore, we measured t...

  9. Using an Existing Crown to Repair a Damaged Cast Post and Core Restoration

    OpenAIRE

    Arabolu, Manikya; Nair, K. Chandrasekharan; Raheel, Syed Ahmed; Tarakji, Bassel; Azzeghaiby, Saleh Nasser; Nassani, Mohammad Zakaria

    2014-01-01

    A fractured coronal tooth structure beneath an intact crown is a common clinical occurrence. If the underlying root is healthy, the tooth is restored with a post and core followed by refabrication of the crown. This paper describes a technique of using the existing intact crown for the above-mentioned situation. A 34-year-old female was referred with a fractured right canine with an intact crown. A post was found fractured in the canal which was subsequently retrieved. A new fiber post was ce...

  10. Evaluation of marginal circumference and marginal thickness changes in precrimped stainless steel crowns, after recrimping

    Directory of Open Access Journals (Sweden)

    Afshar H

    2006-07-01

    Full Text Available Background and Aim: The need for recrimping precrimped stainless steel crowns by the dentist in clinic is controversial. This study aimed to evaluate the rate of marginal circumference and marginal thickness change of precrimped stainless steel crowns after recrimping. Materials and Methods: In this experimental study, 30 primary photos were taken from margins of 30 S.S.Cs (3M, Ni-Cr related to tooth 85 with a digital camera fixed at a determined distance. Margins of crowns were crimped by 114 and 137 pliers with a controlled force (0.2 N and then 30 secondary photos were taken in the same conditions. The circumference of crown margins in primary (group A and secondary (group B photos were assessed by a digitizer system. Comparing the circumferences of crown margins in primary and secondary photos showed a significant decrease after crimping. Thickness of 30 random points on the crown margins of a crown similar to mentioned cases was measured by SEM (×150. Then similar procedures including taking a primary photo, crimping and taking a secondary photo was done for the sample crown. After significant reduction in margin circumference, thickness of 30 other random points on the crown margin were measured by SEM. Data were analyzed by paired sample t-test with p<0.05 as the limit of significance. Results: The mean marginal circumference of precrimped stainless steel crowns was reduced by 7.3% which was significant (P<0.001. On the other hand the mean marginal thickness of sample stainless steel crown showed 18µ increase. Conclusion: According to the results of this study, marginal circumference of precrimped stainless steel crowns (3M, Ni-Cr showed a significant decrease after crimping. It is concluded that crimping the stainless steel crowns even for precrimped ones seems necessary.

  11. Comparison of standardized clinical evaluation of wounds using ruler length by width and Scout length by width measure and Scout perimeter trace.

    Science.gov (United States)

    Langemo, Diane; Spahn, James; Spahn, Thomas; Pinnamaneni, V Chowdry

    2015-03-01

    The study objective was to examine precision in wound measurement using a recently Food and Drug Administration-approved Scout (WoundVision, LLC, Indianapolis, Indiana) device to measure wound length (L) and width (W). Wound perimeter and a ruler measurement of L and W were also made. Images of 40 actual patient wounds were measured using the Scout device. All 3 techniques (length, width, perimeter) demonstrated acceptable within and between reader precision; however, the best precision was in wound perimeter measurement. PMID:25679463

  12. CD4+ T-lymphocyte telomere length is related to fibrosis stage, clinical outcome and treatment response in chronic hepatitis C virus infection.

    OpenAIRE

    FLETCHER, JEAN

    2010-01-01

    PUBLISHED BACKGROUND & AIMS: Increasing age is associated with impaired immune function and in chronic HCV infection specifically, with progressive fibrosis, liver failure, HCC and impaired responses to antiviral therapy. T-lymphocyte telomere length declines with age. We hypothesised that shorter T-lymphocyte telomere length would be associated with poor clinical outcome in HCV infection. METHODS: Circulating T-lymphocyte telomere length, an objective measure of immune senescence, was...

  13. Prosthetic crowns and other clinical risk indicators of caries among old-old Swedish adults: findings from the KEOHS Project. Kungsholmen Elders Oral Health Study

    DEFF Research Database (Denmark)

    Morse, Douglas E; Holm-Pedersen, Poul; Holm-Pedersen, Jytte; Katz, Ralph V; Viitanen, Matti; von Strauss, Eva; Winblad, Bengt

    2002-01-01

    The Kungsholmen Elders Oral Health Study (KEOHS) evaluated the oral health status of generally healthy, community-dwelling persons over the age of 80 living in Kungsholmen, Sweden. This paper explored possible clinical risk indicators of coronal and root caries among the KEOHS subjects.......The Kungsholmen Elders Oral Health Study (KEOHS) evaluated the oral health status of generally healthy, community-dwelling persons over the age of 80 living in Kungsholmen, Sweden. This paper explored possible clinical risk indicators of coronal and root caries among the KEOHS subjects....

  14. Clinical evaluation of selective double gingival retraction technique for anterior all-ceramic crown prosthesis%选择性双线排龈技术在前牙全瓷冠修复中的应用研究

    Institute of Scientific and Technical Information of China (English)

    刘思言; 牟雁东

    2016-01-01

    目的:评价选择性双线排龈技术在前牙全瓷冠修复中的临床应用效果。方法选择126例门诊患者258颗前牙行全瓷冠修复,简单随机法分为两组各63例,试验组130颗基牙采用选择性双线排龈技术排龈,对照组128颗采用单线排龈技术排龈,评价牙龈止血效果满意率、预备体边缘和肩台暴露、游离龈与牙面分离满意率。结果选择性双线排龈技术的牙龈止血效果满意率、预备体边缘和肩台暴露、游离龈与牙面分离满意率分别为96.92%、96.15%及95.38%,明显高于单线排龈技术的83.59%、82.03%及81.25%。差异有统计学意义( P<0.05)。结论在前牙全瓷冠修复中,选择性双线排龈技术有很好的临床应用效果。%Objective To evaluate the clinical application effect of selective double gingival retraction technique for anterior all-ceramic crown prosthesis .Methods Two hundred and fifty-eight anterior all-ceramic crowns from 126 patients were randomly divid-ed into experimental or control groups ,63 cases in each group.Selective gingival retraction technique was used in the experimental group (130 teeth) while singlet gingival retraction technique was used in the control group (128 teeth).The effect on satisfaction rates of gingival hemostasis ,prepared teeth margins and shoulder exposure ,and satisfaction rates of separation of free gingiva and tooth sur-face were evaluated .Results The rates of satisfaction of gingival hemostasis ,prepared teeth margins and shoulder exposure and separa-tion of free gingiva and tooth surface in the selective double gingival retraction group were 96.92%,96.15%and 95.38%,respective-ly,that were significantly higher than that with singlet gingival retraction technique (83.59%,82.03%and 81.25%,respectively) (P<0.05 ) .Conclusion Selective double gingival retraction technique is an effective method for anterior all -ceramic crown prosthesis .

  15. Investigating the effect of clinical governess approach on patients' length of stay in emergency department: an action research study.

    Directory of Open Access Journals (Sweden)

    Tahmine Salehi

    2014-02-01

    Full Text Available Over the past decade, clinical governance approach with aims to improve the quality of health services has been proposed in Iran. Considering the obvious problems especially patients' length of stay (LOS in the emergency departments (EDs; the present study has been carried out with the purpose of Investigating the effect of clinical governess approach on patients' LOS in the one of the largest medical centers in the country. After the problem was specified by the 17 interviews with employees and managers of the ED; the emergency clinical governance committee was formed by two academic researchers and seven ED staff (key participants that had the most involvement with the subject of study. The activities of the committee, including planning, acting, observing and reflecting, was organized by using participatory action research approach and action research cycle (Kemmis 1995. During this time, three formal meetings with key participants were held in 6-month intervals. Monthly records of patients' average LOS and interview with ED staff were used to analyze the findings. The research was completed with two cycles in one year. Committee members took the following actions. As a result, the patients' LOS reduced from 2.68 days to 1.73 days. Make regular patients visits by medical groups especially orthopedists and neurologists; Decision making about patients situation by emergency physicians and transferring patients to the relevant units by bed managers; Refusing to admit elective patients during overcrowding times; to regulate the list of patients requiring ICU by anesthesiologists. Prolonged LOS can be due to various causes and a team approach, which is one of the requirements of clinical governance approach, is needed to manage it. The results showed that the multidisciplinary team could make positive changes and reduce LOS in emergency setting.

  16. 3D statistical failure analysis of monolithic dental ceramic crowns.

    Science.gov (United States)

    Nasrin, Sadia; Katsube, Noriko; Seghi, Robert R; Rokhlin, Stanislav I

    2016-07-01

    For adhesively retained ceramic crown of various types, it has been clinically observed that the most catastrophic failures initiate from the cement interface as a result of radial crack formation as opposed to Hertzian contact stresses originating on the occlusal surface. In this work, a 3D failure prognosis model is developed for interface initiated failures of monolithic ceramic crowns. The surface flaw distribution parameters determined by biaxial flexural tests on ceramic plates and point-to-point variations of multi-axial stress state at the intaglio surface are obtained by finite element stress analysis. They are combined on the basis of fracture mechanics based statistical failure probability model to predict failure probability of a monolithic crown subjected to single-cycle indentation load. The proposed method is verified by prior 2D axisymmetric model and experimental data. Under conditions where the crowns are completely bonded to the tooth substrate, both high flexural stress and high interfacial shear stress are shown to occur in the wall region where the crown thickness is relatively thin while high interfacial normal tensile stress distribution is observed at the margin region. Significant impact of reduced cement modulus on these stress states is shown. While the analyses are limited to single-cycle load-to-failure tests, high interfacial normal tensile stress or high interfacial shear stress may contribute to degradation of the cement bond between ceramic and dentin. In addition, the crown failure probability is shown to be controlled by high flexural stress concentrations over a small area, and the proposed method might be of some value to detect initial crown design errors. PMID:27215334

  17. Digital modeling technology for full dental crown tooth preparation.

    Science.gov (United States)

    Dai, Ning; Zhong, Yicheng; Liu, Hao; Yuan, Fusong; Sun, Yuchun

    2016-04-01

    A dental defect is one of the most common oral diseases, and it often requires a full crown restoration. In this clinical operation, the dentist must manually prepare the affected tooth for the full crown so that it has a convergence angle between 4° and 10°, no undercuts, and uniform and even shoulder widths and depths using a high speed diamond bur in the patient׳s mouth within one hour, which is a difficult task that requires visual-manual operation. The quality of the tooth preparation has an important effect on the success rate of the subsequent prosthodontic treatment. This study involved research into digital modeling technology for full dental crown tooth preparation. First, the margin line of the tooth preparation was designed using a semi-automatic interactive process. Second, the inserting direction was automatically computed. Then, the characteristic parameters and the constraints on the tooth preparation were defined for the model. Next, the shoulder and axial surface of the tooth preparation were formed using parametric modeling. Finally, the implicit surface of a radial basis function was used to construct the tooth preparation׳s occlusal surface. The experimental results verified that the method of digital modeling for full crown preparation proposed in this study can quickly and accurately implement personalized designs of various parameters, such as the shoulder width and the convergence angle; it provides a digital design tool for full crown preparation. PMID:26945598

  18. Wave Forces on Crown Walls

    DEFF Research Database (Denmark)

    Pedersen, Jan; Burcharth, H. F.

    1993-01-01

    This paper presents some of the results from a large parametric laboratory study including more than 200 long-duration model tests. The study addresses both the wave forces imposed on the breakwater crown wall as well as the performance of the structure in reducing the wave overtopping. The testing...... programme includes variations of the sea state parameters and of the geometrical configuration of the breakwater and crown wall. Basic relations between forces/overtopping and the varied parameters are examined and preliminary design guidelines for structures within the tested range of variations are...

  19. A Simple Chairside Technique of Removing Crown and Fixed Partial Denture Restorations

    Directory of Open Access Journals (Sweden)

    Abhinav Gupta

    2014-03-01

    Full Text Available Retrieving failed cemented crowns and fixed partial dentures with minimum discomfort to the patient has always been a clinical concern. This article describes a technique which will allow easy and predictable removal of these restorations.

  20. A Simple Chairside Technique of Removing Crown and Fixed Partial Denture Restorations

    OpenAIRE

    Abhinav Gupta

    2014-01-01

    Retrieving failed cemented crowns and fixed partial dentures with minimum discomfort to the patient has always been a clinical concern. This article describes a technique which will allow easy and predictable removal of these restorations.

  1. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  2. Mechanical Analysis of Dead Load Crown and Structure Parameter of Hydraulic Elastic Bulging Roll

    Institute of Scientific and Technical Information of China (English)

    ZHAO Chang-cai; LI Wei-min; LIU Zhu-bai

    2003-01-01

    The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam, and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve, the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put forward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.

  3. Comparative Evaluation of Enhancing Retention of Dislodged Crowns Using Preparation Modifications and Luting Cements: An In-Vitro Study

    OpenAIRE

    Amarnath, G S; Pandey, Apurva; Prasad, Hari Ananth; Hilal, Mohammed

    2015-01-01

    Background: Complete cast crowns are good alternatives and have best longevity for the restoration of damaged posterior teeth. Occasionally, a crown with clinically acceptable margins, preparation design, and occlusion becomes loose. Providers often debate whether such a crown can be successfully recemented with any degree of confidence that it will not be dislodged under normal masticatory function. It has been documented that resistance form increases by placing grooves opposing each other ...

  4. Implementing a clinical pathway for hip fractures; Effects on hospital length of stay and complication rates in five hundred and twenty six patients

    NARCIS (Netherlands)

    P.T.P.W. Burgers (Paul T. P. W.); E.M.M. van Lieshout (Esther); J. Verhelst (Joost); I. Dawson (Imro); P.A.R. Rijcke (Piet)

    2014-01-01

    textabstractPurpose: Modern management of the elderly with a hip fracture is complex and costly. The aim of this study was to compare the treatment-related hospital length of stay (HLOS) before and after implementing a clinical pathway for patients undergoing hip fracture surgery. Methods: This was

  5. Early complications and performance of 327 heat-pressed lithium disilicate crowns up to five years

    Science.gov (United States)

    2016-01-01

    PURPOSE The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17–73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, Poral hygiene) to reach full success with these crowns. PMID:27350853

  6. Ex vivo fracture resistance of direct resin composite complete crowns with and without posts on maxillary premolars.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Bell, A.M. Le; Kreulen, C.M.; Lassila, L.V.; Vallittu, P.K.; Creugers, N.H.J.

    2005-01-01

    AIM: To investigate ex vivo the fracture resistance and failure mode of direct resin composite complete crowns with and without various root canal posts made on maxillary premolars. METHODOLOGY: The clinical crowns of 40 human extracted single-rooted maxillary premolars were sectioned at the cemento

  7. Fracture behavior of structurally compromised non-vital maxillary premolars restored using experimental fiber reinforced composite crowns.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Kreulen, C.M.; Bell-Ronnlof, A.M. Le; Lassila, L.V.; Vallittu, P.K.; Creugers, N.H.J.

    2006-01-01

    PURPOSE: To study the fracture behavior of direct resin composite crowns with or without experimental fiber reinforcement. METHODS: Clinical crowns of single-rooted maxillary premolars were cut off at the cemento-enamel junction. Canals were prepared with Gates Glidden drills up to size 4. No additi

  8. Evaluation of marginal circumference and marginal thickness changes in precrimped stainless steel crowns, after recrimping

    OpenAIRE

    Afshar H; Mozafari Kojidi M

    2006-01-01

    Background and Aim: The need for recrimping precrimped stainless steel crowns by the dentist in clinic is controversial. This study aimed to evaluate the rate of marginal circumference and marginal thickness change of precrimped stainless steel crowns after recrimping. Materials and Methods: In this experimental study, 30 primary photos were taken from margins of 30 S.S.Cs (3M, Ni-Cr) related to tooth 85 with a digital camera fixed at a determined distance. Margins of crowns were crimped by 1...

  9. The Fixation Technique of Artificial Crowns with Preliminary Preventive Treatment of Tooth Stump

    Directory of Open Access Journals (Sweden)

    Zhulev Е.N.

    2012-09-01

    Full Text Available The article gives the recommendations for artificial crowns cementing using prophylactic drugs aimed at the prevention of complex cavity of hard tissues of a prepared tooth. Preliminary use of prophylactic drug before final fixation of artificial crowns contributes to deep fluorization of hard tooth tissues, and thus, provides long stable positioning of dentures on prepared hard tissues of natural teeth. Clinical trials carried out showed that along with a precisely poured denture and try-in, the technique provides high caries-resistant of hard tooth tissues under an artificial crown.

  10. Evaluation of sampling strategies to estimate crown biomass

    Directory of Open Access Journals (Sweden)

    Krishna P Poudel

    2015-01-01

    Full Text Available Background Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the tree. Crown biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products, fuel load assessments and fire management strategies, and wildfire modeling. However, crown biomass is difficult to predict because of the variability within and among species and sites. Thus the allometric equations used for predicting crown biomass should be based on data collected with precise and unbiased sampling strategies. In this study, we evaluate the performance different sampling strategies to estimate crown biomass and to evaluate the effect of sample size in estimating crown biomass. Methods Using data collected from 20 destructively sampled trees, we evaluated 11 different sampling strategies using six evaluation statistics: bias, relative bias, root mean square error (RMSE, relative RMSE, amount of biomass sampled, and relative biomass sampled. We also evaluated the performance of the selected sampling strategies when different numbers of branches (3, 6, 9, and 12 are selected from each tree. Tree specific log linear model with branch diameter and branch length as covariates was used to obtain individual branch biomass. Results Compared to all other methods stratified sampling with probability proportional to size estimation technique produced better results when three or six branches per tree were sampled. However, the systematic sampling with ratio estimation technique was the best when at least nine branches per tree were sampled. Under the stratified sampling strategy, selecting unequal number of branches per stratum produced approximately similar results to simple random sampling, but it further decreased RMSE when information on branch diameter is used in the design and estimation phases. Conclusions Use of

  11. Relationships of Chamaecyparis formosensis crown shape and parameters with thinning intensity and age

    Directory of Open Access Journals (Sweden)

    Tian-Ming Yen

    2015-12-01

    Full Text Available Taiwan red cypress (Chamaecyparis formosensis Matsum is an indigenousand important cypress conifer with a broad area of natural forests and plantations in Taiwan. Because of the high economic value and multiple uses of the species, numerous researchers have studied its growth and yield within plantation forests. However, few studies have examined how the crown characteristics of the tree respond to different thinning regimes, particularly in the long run. The crown is a dominant outline of aboveground component of a tree that can sensitively reflect competitions from trees located nearby. This study evaluated the crown form of Taiwan red cypress at three different growth stages with different thinning intensities over 20 years. The study began in 1982, when the three plantations examined were aged 7, 15, and 21 years, and when thinning treatments began. In 2002, crown form parameters (CFPs and crown profile equations (CPEs were used to analyze the thinning effects at the tree level. Two-way analysis of variance (ANOVA revealed that age class influenced most CFPs and that thinning treatments influenced all CFPs, indicating that both factors could simultaneously affect the CFPs. Moreover, the CPEs fit the observed data well for all age classes, demonstrating that the equation had a high capacity for predicting crown form. The CPEs were used to determine the mean crown shape profile for each thinning treatment and age class. According to the mean crown profile predicted by CPEs, we found that crown length and width increased with thinning intensity for all aged trees, especially after a heavy thinning treatment.

  12. Marginal accuracy of temporary composite crowns.

    Science.gov (United States)

    Tjan, A H; Tjan, A H; Grant, B E

    1987-10-01

    An in vitro study was conducted to quantitatively compare the marginal adaptation of temporary crowns made from Protemp material with those made from Scutan, Provisional, and Trim materials. A direct technique was used to make temporary restorations on prepared teeth with an impression as a matrix. Protem, Trim, and Provisional materials produced temporary crowns of comparable accuracy. Crowns made from Scutan material had open margins. PMID:2959770

  13. Avaliação das condutas adotadas por profissionais na utilização de coroas metalo-cerâmicas Assessment of clinical proceedings adopted by dental professionals regarding the employment of ceramic fused to metal crowns

    Directory of Open Access Journals (Sweden)

    Carlos Neanes Santos

    2003-12-01

    Full Text Available A fim de avaliar a opinião da classe odontológica sobre a utilização das coroas metalo-cerâmicas na prática odontológica, aplicou-se um questionário de 20 questões a cirurgiões-dentistas da cidade de Aracaju - SE, e a cirurgiões-dentistas e estudantes de pós-graduação em odontologia, na área de prótese dental, da cidade de Bauru-SP. Concluiu-se que: 1. As coroas metalo-cerâmicas são o tipo de restauração protética mais empregado em Odontologia. 2. A maioria dos dentistas refere-se às coroas metalo-cerâmicas como restaurações bem sucedidas, indicando superfícies oclusais metálicas para a maioria dos pacientes. 3. Apesar da maior parte dos profissionais utilizar as ligas de níquel-cromo nas coroas metalo-cerâmicas de seus pacientes, os mesmos prefeririam que ligas nobres ou semi-nobres fossem empregadas em suas próprias restaurações. 4. A maioria dos entrevistados emprega as coroas metalo-cerâmicas na restauração de dentes anteriores (57,23%. Entretanto, esse valor se deve à preferência dos dentistas de Aracaju (78% por esse tipo de restauração, ao passo que, em Bauru, prevaleceu o número de respostas favoráveis às coroas de porcelana pura. 5. O cimento de fosfato de zinco foi o cimento de escolha da maioria dos profissionais. 6. A preferência da maior parte dos entrevistados, com relação à porcelana utilizada foi pela porcelana Vita (34,34%, em comparação às porcelanas Noritake e Dulceram Plus (13,86%. 6. Ficou evidente o desejo dos entrevistados quanto ao desenvolvimento de mecanismos que facilitem o reparo das coroas metalo-cerâmicas.The current features of ceramic fused to metal crowns were evaluated by means of a questionnaire composed by 20 questions concerning the use of this type of restoration in the daily dental practice of professionals from Aracaju, Bauru and post-graduation students in the area of dental prosthesis. The conclusions were as follows: 1. Ceramic fused to metal crowns are

  14. Pemakaian Crown Loop dan Band Loop di Rahang Bawah Anak Usia Enam Tahun (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Rivi Isabela

    2015-11-01

    Full Text Available The function of space maintainer is to preserve arch length following the premature loss of a primary teeth. Early loss of primary tooth may compromise the eruption of succedaneous teeth if there is a reduction in the arch length. The Band and Crown Loop are used to maintain the loss of primary molar. The report describe a 6 year old girl who has premature loss of second left mandibular primary molar and first right mandibular primary molar treated using crown and band loop space maintainer. The patient still has mastication function from other posterior primary teeth.

  15. Computer model of running crown forest fire

    OpenAIRE

    Barovik, D. V.; Taranchuk, V. B.

    2010-01-01

    Adapted mathematical model of running crown forest fire propagation is considered. The results of computer modelling and the peculiarities of forest fire behavior in heterogeneous forests are discussed.

  16. Pericoronal radiolucency associated with incomplete crown

    Energy Technology Data Exchange (ETDEWEB)

    Nah, Kyung Soo [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2013-12-15

    The author experienced 8 cases of pericoronal radiolucency involving an incomplete tooth crown that had not developed to form the cemento-enamel junction, and the underdeveloped crown sometimes appeared to be floating within the radiolucency radiographically. The first impression was that these cystic lesions had odontogenic keratocysts, but half of them turned out to be dentigerous cysts histopathologically. There has been no report concerning odontogenic cysts involving an incompletely developed crown. The purpose of this paper is to report that dentigerous cysts may develop before the completion of the cemento-enamel junction of a developing crown.

  17. Full mouth rehabilitation of partially and fully edentulous patient with crown lengthening procedure: a case report

    OpenAIRE

    Seol, Hyon-Woo; Koak, Jai-Young; Kim, Seong-Kyun; Heo, Seong-Joo

    2010-01-01

    BACKGROUND In order to restore severely attrited teeth properly, surgical intervention in the form of a crown-lengthening procedure may be required. And also, proper diagnosis and treatment sequencing is critical to obtain a successful results. Adequate diagnostic wax-up ensures good esthetics and healthy periodontal tissue. CASE DESCRIPTION This clinical case report describes a diagnostically based protocol for restoration on mandibular anterior teeth with crown lengthening procedure and the...

  18. Clinical analysis of the influence of temporary crowns on abutment and implant after tooth preparation%牙体制备后临时冠桥修复对基牙及修复体影响的临床分析

    Institute of Scientific and Technical Information of China (English)

    吴启建; 徐敏; 李桂苓

    2015-01-01

    Objective Analysis the effect of temporary crown and bridge repair on the abutment and dental restoration. Methods Randomly selected 80 patients between 2013-2014 a clinical investigation, using retrospective analysis method, the application of direct or indirect method, improve the function, cosmetic repair effect.Results All patients were back on time,within the given time line PFM, casting crown and bridge repair, clinical observation, try effect is good,smooth in place restoration,restoration margin closed closed, try occlusal height is normal, no displacement of abutment teeth, no missing area, elongation polices jaw teeth.Temporary crown bridge can protect the abutment teeth, protect fix clearance and occlusal relationship, avoid teeth mobile embedded plug caused by food, maintain a healthy oral and periodontal tissue. Play a good role.Conclusion The temporary crown and bridge of protect teeth, worth clinical promotion.%目的:分析牙体制备后临时冠桥修复对基牙及修复体的影响。方法选取2013~2014年我院收治的患者80例,采用回顾分析法,应用直接或间接制作方法,提高功能,美观的修复效果。结果本组患者均在规定时间内按时复诊,行烤瓷、铸造冠桥的修复,临床观察,试戴效果良好,顺利就位修复体,修复体边缘封闭密合,试戴咬合高度正常,无基牙移位,无缺失区,対颌牙伸长。临时冠桥的制作能保护基牙,保护修复间隙和咬合关系,避免牙齿移动引起食物嵌塞,维护口腔牙周组织健康。结论临时冠桥所起到的保护牙齿作用,值得临床推广使用。

  19. Clinical research of long-term aesthetic results of the anterior region of zirconia all-ceramic crown%氧化锆全瓷冠在前牙美学修复中的临床应用研究

    Institute of Scientific and Technical Information of China (English)

    王红梅; 杨永进; 蔡兴伟; 郭军; 吕晓宁

    2012-01-01

    目的:探讨氧化锆全瓷冠在前牙美学修复中的应用效果和美学效果的稳定性及其相关影响因素.方法:应用CAD/CAM技术,对20例前牙要求美学修复的患者,共44颗前牙进行氧化锆全瓷冠修复,修复后定期随访2年,通过观察患者对全瓷冠颜色的满意程度,全瓷冠颜色的口内适应情况,颜色的改变情况及牙龈组织的健康状况等,来综合评价氧化锆全瓷冠在前牙美学修复中的应用效果.结果:氧化锆的比色效果在口内的适应性较好,自然美观;两年内患者对其美学效果的评价一致,满意程度高;两年随访观察中只有2例吸烟的男性患者发生颜色改变,其余患者颜色均未发生明显改变,牙龈健康状况良好.结论:氧化锆全瓷冠的前牙美学修复效果良好且稳定,患者满意,具有广阔的应用前景.%Objective To study the repair effect, stability of aesthetic effect and its related factors of zirconia all-ceramic crowns in the anterior dental esthetics restoration. Methods 20 patients who with requirements of anterior teeth aesthetics restoration, a total of 44 anterior teeth of zirconia all-ceramic crown restoration using the CAD/CAM tecnolory, and regular follow-up of 2 years after repair. Then compare the patients' satisfactions on all-ceramic crown color, all-ceramic crown color intraoral adaptation, color changes and the gum tissue health to evaluate the application effect of zirconia all-ceramic crowns in the anterior dental esthetics repair comprehensively. Results The colorimetric effect of zirconia is natural appearance in the mouth; all the patients show high levels of satisfaction during two years follow-up observation on the aesthetic evaluation of the effect of consistent.Only two smoking male patients with color change and the remaining patients had no obvious color change.and the gingival health is good. Conclusion The repair effect of zirconia all-ceramic crown of anterior dental esthetics is

  20. Identification of cultured isolates of clinically important yeast species using fluorescent fragment length analysis of the amplified internally transcribed rRNA spacer 2 region

    Directory of Open Access Journals (Sweden)

    Muylaert An

    2002-07-01

    Full Text Available Abstract Background The number of patients with yeast infection has increased during the last years. Also the variety of species of clinical importance has increased. Correct species identification is often important for efficient therapy, but is currently mostly based on phenotypic features and is sometimes time-consuming and depends largely on the expertise of technicians. Therefore, we evaluated the feasibility of PCR-based amplification of the internally transcribed spacer region 2 (ITS2, followed by fragment size analysis on the ABI Prism 310 for the identification of clinically important yeasts. Results A rapid DNA-extraction method, based on simple boiling-freezing was introduced. Of the 26 species tested, 22 could be identified unambiguously by scoring the length of the ITS2-region. No distinction could be made between the species Trichosporon asteroides and T. inkin or between T. mucoides and T. ovoides. The two varieties of Cryptococcus neoformans (var. neoformans and var. gattii could be differentiated from each other due to a one bp length difference of the ITS2 fragment. The three Cryptococcus laurentii isolates were split into two groups according to their ITS2-fragment lengths, in correspondence with the phylogenetic groups described previously. Since the obtained fragment lengths compare well to those described previously and could be exchanged between two laboratories, an internationally usable library of ITS2 fragment lengths can be constructed. Conclusions The existing ITS2 size based library enables identification of most of the clinically important yeast species within 6 hours starting from a single colony and can be easily updated when new species are described. Data can be exchanged between laboratories.

  1. Genetic Diversity of Trichomonas vaginalis Clinical Isolates Determined by EcoRI Restriction Fragment Length Polymorphism of Heat-Shock Protein 70 Genes

    OpenAIRE

    Meade, John C.; de Mestral, Jacqueline; Jonathan K Stiles; Secor, W. Evan; Finley, Richard W.; Cleary, John D.; Lushbaugh, William B.

    2009-01-01

    Restriction fragment length polymorphism (RFLP) analysis using a multilocus heat-inducible cytoplasmic heat-shock protein 70 (Hsp70) hybridization probe with EcoRI-digested genomic DNA was used in molecular typing of 129 Trichomonas vaginalis isolates. Results indicate that Trichomonas organisms exhibit considerable polymorphism in their Hsp70 RFLP patterns. Analysis of seven American Type Culture Collection reference strains and 122 clinical isolates, including 84 isolates from Jackson, Miss...

  2. Clinical study of telescopic crown retained denture on the restoration of dentition defect in patients with light, modertate periodontal disease%筒冠义齿修复轻中度牙周炎伴多数牙缺失的疗效观察

    Institute of Scientific and Technical Information of China (English)

    王红梅; 杨永进; 蔡兴伟; 吕晓宁; 李雅彬; 李晖

    2012-01-01

    目的:探讨多数牙缺失伴牙周病的牙列缺损患者应用套筒冠修复的临床效果.方法:选择多数牙缺失并有可摘局部义齿修复史的轻中度牙周炎患者36例,行牙周基础治疗和根管治疗后设计、制作套筒冠义齿,比较分析修复前和修复后6、12、24个月菌斑指数(PLI)、牙龈指数(GI)、探诊深度(PD)、龈沟出血指数(SBI)、牙齿松动度,并进行问卷调查.结果:36例患者在修复后3次复查时牙齿松动度和牙周袋深度(PD)逐渐变小(P0.05);随访问卷调查结果显示,患者对套筒冠义齿满意度明显高于活动义齿.结论:套筒冠义齿修复轻中度牙周炎伴多数牙缺失的牙列缺损具有较好的临床效果.%Objective: To explore the clinical result of using telescopic crown retained denture to restore dentition defect in patients with most teeth missing and periodontal disease. Methods: Thirty-six cases with dentition defect and periodontal disease were recruited. After the comprehensive periodontal therapy and root canal treatment, telescopic crown retained partial dentures were made and tried in. Plaque index (PLI), gingival index (GI), probing index(PD), sulcus bleeding index (SBI) and mobility of teeth were checked and recorded before and 6, 12, 24 months after restoration. The patients were investigated with questionnaires concerning the results. Results: Teeth mobility and PD were significantly improved (P0.05). The results of questionnaires indicated that the patients were much more satisfied with telescopic crown dentures than their original removable partial dentures. Conclusion: Using telescopic crown retained dentures to repair dentition defect in patients with periodontal disease could ensure good clinical results.

  3. 21 CFR 872.3330 - Preformed crown.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Preformed crown. 872.3330 Section 872.3330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... gums). It is intended for use as a functional restoration until a permanent crown is constructed....

  4. The use of tree crown variables in over-bark diameter and volume prediction models

    Directory of Open Access Journals (Sweden)

    Özçelik R

    2014-06-01

    Full Text Available Linear and nonlinear crown variable functions for 173 Brutian pine (Pinus brutia Ten. trees were incorporated into a well-known compatible volume and taper equation to evaluate their effect in model prediction accuracy. In addition, the same crown variables were also incorporated into three neural network (NN types (Back-Propagation, Levenberg-Marquardt and Generalized Regression Neural Networks to investigate their applicability in over-bark diameter and stem volume predictions. The inclusion of crown ratio and crown ratio with crown length variables resulted in a significant reduction of model sum of squared error, for all models. The incorporation of the crown variables to these models significantly improved model performance. According to results, non-linear regression models were less accurate than the three types of neural network models tested for both over-bark diameter and stem volume predictions in terms of standard error of the estimate and fit index. Specifically, the generated Levenberg-Marquardt Neural Network models outperformed the other models in terms of prediction accuracy. Therefore, this type of neural network model is worth consideration in over-bark diameter and volume prediction modeling, which are some of the most challenging tasks in forest resources management.

  5. Impact resistance of crowned endodontically treated central incisors with internal composite cores.

    Science.gov (United States)

    Cathro, P R; Chandler, N P; Hood, J A

    1996-06-01

    The impact fracture resistance of crowned endodontically treated teeth with composite cores but without posts, that had either no coronal dentin remaining or a 1 mm dentin collar was compared to that of unrestored caries free teeth. The teeth were struck mid-labially to simulate a common trauma situation using a pendulum device and fracture resistance determined by calculation of absorbed energies. No significant difference was found between the intact teeth and the crowned root treated teeth with composite core and a 1 mm dentin collar. Crowned root treated teeth with a composite core but no coronal dentin had significantly reduced fracture resistance (p fractured obliquely from the buccal crown margin to a point coincident with the simulated alveolus, representing a clinical situation which would allow retention rather than extraction of the tooth. PMID:9028189

  6. The clinical study on abutment dentin hypersensitivity after preparation for crown and bridge%冠桥基牙制备后牙本质敏感的临床治疗研究

    Institute of Scientific and Technical Information of China (English)

    邓文正; 郭庆; 陆辉; 邱伟芳

    2013-01-01

    Objective To evaluate the effects of professional oral allergy desensitization paste for treating abutment dentin hypersensitivity after preparation for Crown and bridge.Methods 226 patients,repaired by porcelain Crown and bridge,were randomly divided into test group and control group,n =113.Test group:Professional oral allergy desensitization paste was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Control group:Gluma desensitizer was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Adopted cold air blowing,dentin sensitivity was evaluated by recording the value of visual analogue pain scores (VAS).Results The abutment sensitivity of the test group,by using desensitizing paste therapy after tooth preparation,significantly reduced.The abutment sensitivity after desensitizing paste therapy was statistically significant compared with that of before using desensitization paste and control group (P<0.001).The abutment sensitivity of test group was statistically significant compared with that of control group after the ceramic Crown and bridge was bonded (P<O.O01).Conclusion Professional oral allergy desensitization paste has good effect on treating abutment dentin hypersensitivity after preparation for Crown and bridge.%目的:评价抗敏口腔专业用脱敏膏对于烤瓷冠桥基牙制备后牙本质过敏的治疗疗效.方法:选取做烤瓷冠桥修复的226例患者,随机分为实验组和对照组,各113例.实验组:113例备牙后和烤瓷冠桥粘固前使用抗敏口腔专业用脱敏膏进行脱敏.对照组:113例备牙后、烤瓷冠桥粘固前使用Gluma脱敏剂脱敏.牙本质敏感度的评价采用冷空气喷吹法,记录视觉模拟疼痛评分(visual analogue scale,VAS)值.结果:实验组于备牙后使用脱敏膏治疗基牙敏感显著降低,与使用前对照组比较差异有统计学意义(P<0.001);与对照组相比,实验组粘固后基牙敏

  7. Dental ceramics and the molar crown testing ground

    Directory of Open Access Journals (Sweden)

    Van P. Thompson

    2004-01-01

    Full Text Available All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior, and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above.

  8. Fabrication of all-ceramic crowns by a new method.

    Science.gov (United States)

    Masuda, Takayuki; Kakimoto, Kazutoshi; Takahashi, Kazuya; Komasa, Yutaka

    2016-01-01

    A new method of all-ceramic production using alumina coping has been developed. The present study investigates the influence of secondary firing (glass infiltration firing) conditions. Samples of porcelain build-up without secondary firing were also assessed. The suitability of coping that included secondary firing was found to be affected by the rate of temperature increase during the secondary firing. However, cracking developed in the fired porcelain if porcelain was built up onto secondarily-fired coping. In contrast, cracking did not occur with coping that was not secondarily fired. The bending strength after porcelain build-up was 70 MPa or higher, suggesting the possibility of clinical applications as an anterior crown. These findings establish that this is method of producing all-ceramic crowns that allows for low-cost manufacture in a short period of about 1 h. PMID:27041020

  9. Evaluation of the marginal and internal gap of metal-ceramic crown fabricated with a selective laser sintering technology: two- and three-dimensional replica techniques

    OpenAIRE

    Kim, Ki-Baek; Kim, Jae-Hong; Kim, Woong-Chul; Kim, Hae-Young; Kim, Ji-Hwan

    2013-01-01

    PURPOSE One of the most important factors in evaluating the quality of fixed dental prostheses (FDPs) is their gap. The purpose of this study was to compare the marginal and internal gap of two different metal-ceramic crowns, casting and selective laser sintering (SLS), before and after porcelain firing. Furthermore, this study evaluated whether metal-ceramic crowns made using the SLS have the same clinical acceptability as crowns made by the traditional casting. MATERIALS AND METHODS The 10 ...

  10. 分根术加全冠修复大面积髓室底穿孔磨牙的临床疗效观察%Clinical effectiveness of root separation and full crown rapair on treatment of large areas perforation of dental pulp floor of molars

    Institute of Scientific and Technical Information of China (English)

    汪文银; 朱友家

    2013-01-01

    Objective:To investigate the clinical effectiveness of root separation and full crown rapair on treatment of large areas perforation of dental pulp floor of molars. Method: 120 out patients that had large areas perforation of dental pulp floor of molars were randomly dived into the experimental group and control group 60 cases. Experimental group use the treatment of root separation and full crown rapair,control group use the treatment of light-cured calcium hydratide and zinic phosphate cement basing with amalgam restoration and full crown repair. Result:Successful rate of experimental group was 83.33 %,response rate was 96.67 %. Successful rate of control group was 43.33 %,response rate was 83.33 %,there was a significant difference between two groups(P <0.01). Conclusion:The use of root separation and full crown rapair can obtain a better effect for treatment of large areas perforation of dental pulp floor of molars.%目的:观察分根术加全冠修复大面积髓室底穿孔磨牙的临床疗效.方法:门诊收治陈旧性大面积髓室底穿孔(直径>3 mm)的磨牙病例120例.随机分成实验组60例,对照组60例.实验组采用分根术加全冠修复治疗,对照组采用光固化型氢氧化钙,磷酸锌粘固粉垫底,银汞充填.全冠修复治疗.结果:随访3~5年,实验组成功率83.33%,有效率96.67%,对照组成功率43.33%,有效率83.33%.实验组临床疗效明显优于对照组(P<0.01).结论:分根术加全冠修复大面积髓室底穿孔磨牙具有较好的临床疗效.

  11. Influence of different post core materials on the color of Empress 2 full ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    GE Jing; WANG Xin-zhi; FENG Hai-lan

    2006-01-01

    Background For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration.Methods The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than △E 1.8 between the two ceramic samples. So, △E 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction.Results When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (△E = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (△E = 2.0), but with opaque covering, the color effect became more clinically satisfactory (△E=1.8).Conclusions It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after coveting the labial surface of the core with one layer of opaque resin cement.

  12. Effect of Luting Cement Space on the Strain Response of Gold Crowns Under Static Compressive Loading.

    Science.gov (United States)

    Asbia, S; Ibbetson, R; Reuben, B

    2015-03-01

    The aim the work was to investigate the effect of varying degrees of luting cement thickness on the strain of the cemented gold alloy crowns under compression. Five dies with their corresponding crowns were fabricated using a lost wax technique. Three gold crowns for each die were fabricated under the control of specific die spacer layers to provide a space of 40 µm (10 layers of die-spacer thickness) and 80 µm (20 layers of die-spacer thickness). The crowns were subsequently cemented using zinc phosphate cement. The crowns were subjected to gradual static compressive loading between 10N to 250N (Newton) and the strain measured simultaneously. The results were statistically analysed using Independent t-test for the different die-spacer thickness at the 95% confidence interval (p = 0.05). It was found that a significant relationship in the three thicknesses. It was concluded that the absence of die-spacer significantly reduced strain response, whereas a very little change in the strain recorded as the die spacer layers has increased. Clinically, decreasing the number of die-spacer layers is advantageous as it provides a lower strain response under static compressive loading that would improve the longevity of the cemented full crowns inside the patient's mouth. PMID:26415332

  13. The aesthetic treatment for anterior teeth with lost crown by endorestoration

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2009-06-01

    Full Text Available Background: The aesthetic has an important role in social life, especially the anterior teeth. The aesthetic abnormality of anterior teeth i.e. discoloration, malpotition or the anterior teeth with crown damage for more than one third or all part of crown is lost due to caries or other causes, will influence its appearance especially during smile. Purpose: The aim of this case report, therefore, is to show how teeth with clinical crown lost or only the root left still can be treated by endorestoration treatment in order to reconstruct the shape and function of the teeth similar to the original ones. Case: Female 52 years old with the lost crown of anterior teeth. The patient did not want her teeth to be extracted. Case Management: The abnormality of these teeth are still able to be reconstructed by endorestoration i.e. endodontic treatment with post and core insertion in the root canal will increase its retention and recovery by the porcelain crown fused to metal to recover the original formation and aesthetic and thus has the normal refunction. The treatment, it improve the confidence of the patient, and also can function normally. The patient did not feel pain. Ronsenography showed the periapical lesion diminished, the neighbor gingival was going better in both function and color. Conclusion: Endorestoration treatment on the anterior teeth with lost crown could recover the normal function, dental aesthetic and self confidence.

  14. Antibody specific for Escherichia coli J5 cross-reacts to various degrees with an Escherichia coli clinical isolate grown for different lengths of time.

    OpenAIRE

    McCallus, D E; Norcross, N. L.

    1987-01-01

    Rabbit antiserum raised against the rough mutant of Escherichia coli O111:B4, designated J5, was examined for cross-reactivity to an E. coli clinical isolate (A2385). In whole-cell enzyme-linked immunosorbent assays, J5 antiserum reacted to a greater extent with A2385 grown for 5 h than with the same bacteria grown for 19 h, while the homologous antiserum reacted similarly with bacteria grown for different lengths of time. J5 antiserum reacted to the greatest extent with lipopolysaccharide (L...

  15. Calix[4] crowns with Methoxynaphthoylmethyl Pendant Groups

    Institute of Scientific and Technical Information of China (English)

    金传明; 陆国元; 张超智; 施证伟; 游效曾

    2003-01-01

    The novel calix [4] crowns with two pendant groups were prepared by the alkylation of calix 141 crowns with 6-methoxy-2-bromoacetylnaphthalene. 1H NMR titration and picrate extraction experiments indicated that they exhibit higher complexing efficiency than their parent compounds and possess obvious selectivity for Na+ or K+ , respetively, and that the cation is encapsulated inside the preorganized ionophoric cavity defined by carbonyl oxygens, the crown ether and the phenoxy oxygens.From UV and fluorescent spectra it is revealed that calix [4]crown-4 3a with 6-methoxy-2-naphthoylmethyl pedant groups exhibits remarkable cation-induced photophysical effects and it could be utilized as a selective fluorescent sensor for Ca2+.

  16. Activity relationships for aromatic crown ethers

    CERN Document Server

    Wilson, M J

    1998-01-01

    This thesis involves an investigation of aromatic crown ethers and a study of their binding constants for alkali metals. The study was motivated by the current needs of the semiconductor industry to improve the scavenging of mobile ions from fabricated circuits. A number of aromatic crown ethers have been sulphonated in an attempt to improve their water solubility and cation binding activity. These materials have been extensively studied and their binding activity determined. In collaboration with a molecular modelling study, the effect of ionisable sulphonate groups on the macrocycles' behaviour has been investigated. The broader issue of the effect of substituents in aromatic crown ethers has also been studied with the preparation of a wide range of substituted crown ethers. The cation binding activity of these materials has been found to bear a simple relationship to the electron withdrawing nature of the aromatic substituents. This relationship can be accurately monitored using electronic charge densities...

  17. The clinical effect of direct pulp capping with multi-cal in crown fracture with pulp exposure in incisors%氢氧化钙糊剂治疗前牙冠折露髓的短期疗效观察

    Institute of Scientific and Technical Information of China (English)

    张文奎; 刘勇

    2011-01-01

    目的 观察氢氧化钙糊剂治疗前牙冠折露髓的短期治疗效果.方法 回顾性分析14例使用氢氧化钙糊剂+爱诺赛光固化复合体+可乐丽菲露树脂修补前牙冠折露髓(≤2 mm)患者的临床资料,评价此方法的短期治疗效果.结果 14例患者共16颗患牙1例患者的1颗患牙因冠髓部分切除行直接盖髓术后第2天出现自发痛及夜间痛复诊,诊断为急性牙髓炎,局部麻醉下行一次性根管治疗;其余13例患者的15颗患牙3个月内均无自发疼痛,临床及X线检查无异常.短期观察治疗成功率为93.8%.结论 氢氧化钙糊剂在前牙冠折露髓中有较好的治疗效果.%Objective To evaluate the method in treatment pulp exposure caused by crown fracture with Multi-cal and the its clinical effect. Methods In the retrospective study, 14 cases ( 16 teeth)were treated to repair pulp exposure with Multi-cal, Ionosit-Baseliner, SE-BOUND and AP-X after debridement. To evaluate the result in short-term with pulp vitality detection and X-ray after three months. Results One tooth treated with direct pulp capping after partial crown-pulptomy appeared spontaneous pain and night pain. The tooth was diagnosed with acute pulpitis and treated with one-step root canal therap under local anesthesia. Other 15 teeth were successfully treated.in 3 months with no spontaneous pain. Clinical and X-ray examination were normal. The success rate was 93.8% in short-term. Conclusion Multi-cal is an effective material in treatment of crown fracture with pulp exposure.

  18. Extraction of lanthanides with lipophilic crown ether carboxylic acids for neutron activation analysis

    International Nuclear Information System (INIS)

    Sym-dibenzo-16-crown-5-oxyacetic acid (I) and its modified analogues (II) and (III) were applied to the extraction of the lanthanides in solutions with high ionic strength and complex matrices. Increasing the length of the side arm alkyl group increases the lipophilicity of the crown ether carboxylic acids and enhances the distribution ratio of the lanthanide-macrocycle complexes in the organic phase. Three lanthanides, La, Eu, and Lu, in natural waters were analyzed by extraction with 2-(sym-dibenzo-16-crown-5-oxy)-steraric acid followed by neutron activation analysis (NAA). The extraction method combined with NAA is capable of detecting the lanthanides at 10-4 μg/L level in complex aqueous systems

  19. Convergence in light capture efficiencies among tropical forest understory plants with contrasting crown architectures: a case of morphological compensation.

    Science.gov (United States)

    Valladares, Fernando; Skillman, John B; Pearcy, Robert W

    2002-08-01

    Leaf and crown characteristics were examined for 24 tree and herbaceous species of contrasting architectures from the understory of a lowland rainforest. Light-capture efficiency was estimated for the crowns of the different species with a three-dimensional geometric modeling program. Causal relationships among traits affecting light absorption at two hierarchical levels (leaf and whole crown) were quantified using path analysis. Light-capture and foliage display efficiency were found to be very similar among the 24 species studied, with most converging on a narrow range of light absorption efficiencies (ratio of absorbed vs. available light of 0.60-0.75). Exceptionally low values were found for the climber vines and, to a lesser extent, for the Bromeliad Aechmea magdalenae. Differences in photosynthetic photon flux density (PFD) absorbed per unit leaf area by individual plants were mostly determined by site to site variation in PFD and not by the differences in crown architecture among individuals or species. Leaf angle, and to a lesser extent also supporting biomass, specific leaf area, and internode length, had a significant effect on foliage display efficiency. Potential constraints on light capture such as the phyllotactic pattern were generally offset by other compensatory adjustments of crown structure such as internode length, arching stems, and plagiotropy. The variety of shoot morphologies capable of efficiently capturing light in tropical forest understories is greater than initially thought, extending over species with very different phyllotactic patterns, crown architectures, leaf sizes, and morphologies. PMID:21665729

  20. Autogenous tooth fragment reattachment: A multidisciplinary management for complicated crown-root fracture with biologic width violation

    Directory of Open Access Journals (Sweden)

    Vinaya Kumar Kulkarni

    2014-01-01

    Full Text Available Fractures of multiple permanent anterior teeth can be a traumatic experience for children, with functional, esthetic and psychological aspects. The treatment of complicated crown-root fractures (CRFs is more challenging when the biologic width is violated. This paper presents a case of 12-year boy with complicated CRF of teeth #12 and #21, and horizontal crown fracture of tooth #11. It was managed by endodontic treatment, mucoperiosteal surgery with osteotomy to visualize the fracture line for fragment reattachment, followed by fiber-post placement and restoration with polycarbonate crowns. Clinical and radiographic evaluation after 6 months was satisfactory with adequate functional and esthetic results.

  1. Clinical study of crown shape control effect of horizontal food impaction in implant supported fixed denture in elderly patients%牙冠形态对老年种植修复患者水平型食物嵌塞防治效果的临床研究

    Institute of Scientific and Technical Information of China (English)

    崔广; 刘宇; 郑洁; 宫琳

    2014-01-01

    目的:观察不同邻面形态的种植单冠修复后对老年种植患者后牙水平型食物嵌塞的防治效果。方法:将80例老年患者第一磨牙种植冠按修复间隙的大小分成两组(A组距离<10.0mm, B组≥10.0mm),组内再随机分为对照组和试验组各20例,分别按照不同邻面形态制作硬质树脂临时冠并戴入,两两对比并进行随访观察。所有病例在观察6个月后拆除硬质树脂临时冠,使用全解剖形态氧化锆种植冠完成最终修复。结果:不同大小的修复间隙,对照组食物嵌塞情况均严重于试验组,两者存在显著性差异(P<0.05)。结论:针对不同大小的修复间隙,特殊的种植冠邻面形态短期内有利于防治老年患者后牙水平型食物嵌塞,长期的临床效果需进一步研究证实。%Objective:Food impaction is one of the main complications of fixed partial denture restoration, and implant supported fixed partial denture is no exception, especially horizontal food impaction. The current study aim to examine the treatment effects of food impaction by adjusting the interproximal contour of the implant crowns.Method:80 cases of posterior teeth restored with implant crowns were randomly divided into group A(<10.0mm), and group B(≥10.0mm), according to the edentulous space. Each group was then subdivided into two groups, each with 20 cases, that were restored with temporary resin crown of different interproximal contour, replaced by zirconia-ceramic crowns 6 month later. Proximal contact, the occurrence of horizontal food impaction and clinical parameters were recorded at each time point. All results were futher compared and analyzed statistically.Results:In group A, the food impaction rate of the control group and experimental group was 80% and 25%, respectively. In group B, the food impaction rate of the control group and experimental group was 100% and 15%, respectively. The food impaction rates of both experiment

  2. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  3. Clinical analysis on removable partial denture in Kennedy Ⅰ dentition defect after Loose abutments were fixed by combined crowns%联冠固定松动基牙后可摘义齿修复肯氏I类牙列缺损的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    顾斌; 李萍; 刘娜; 刘洪臣

    2012-01-01

    Objective: To evaluate clinical therapeutic effect of removable partial denture on Kennedy I dentition defect after loose abutment were fixed by combined crowns or stabilized by continuous clasp. Methods: Forty patients of Kennedy I dentition defect with loose premolars were collected and divided into 2 groups randomly. Before the restoration with removable partial denture, loose abutments in one group were fixed with combined porcelain fused to metal crowns, while those in the other group were repaired with continuous clasp. Effects of two kinds of treatment were evaluated respectively after 1-5 years follow-up period. Statistic analysis was performed. Results: At 5 years, the success ration of combined porcelain fused to metal crowns group was better than continuous clasp group. The differences of satisfaction rate, plaque control record, probing depth, clinical attachment loss, bleeding on probing and bone support were significant (P<0.05). Conclusion: Good clinical effect of RPD in Kennedy I dentition defect might be obtained after loose abutments were fixed by combined crowns combined with complete periodontal therapy.%目的:分别用烤瓷联冠固定基牙和连续高位卡环稳定基牙,利用可摘局部义齿(removable partial denture,RPD)修复双侧磨牙缺失,比较两者间的临床疗效.方法:选取肯氏Ⅰ类牙列缺损近缺失端基牙I-II度松动病例40例,在进行完善的牙周基础治疗后,分别采用烤瓷联冠固定基牙和连续高位卡环稳定基牙,行可摘局部义齿修复.术后复查,随访1-5年,通过比较患者的主观感受和临床检查结果进行疗效评价.结果:烤瓷联冠组5年临床成功率高于连续高位卡环组,两组患者的满意率、牙周菌斑指数、牙周袋探诊深度、临床附着水平、探诊后出血指数、牙槽骨支持指数差异有统计学意义(P<0.05).结论:对肯氏I类牙列缺损伴前磨牙松动的患牙,经完善的牙周治疗后,烤瓷联冠固定松动

  4. Skin conductance, Marlowe-Crowne defensiveness, and dental anxiety.

    Science.gov (United States)

    Benjamins, C; Schuurs, A H; Hoogstraten, J

    1994-08-01

    The present study assesses the relationship between self-reported dental anxiety (Dental Anxiety Inventory, Dental Anxiety Scale, and Duration of Psychophysiological Fear Reactions), electrodermal activity (skin-conductance level and frequency of spontaneous responses), and Marlowe-Crowne defensiveness. All measurements were made twice. The first session was scheduled immediately before a semi-annual dental check-up (stress condition), and baseline measurements were made two months later without the prospect of a dental appointment. Subjects were male dental patients who regularly attended a university dental clinic and a clinic for Special Dental Care. The main findings were that the low anxious-high defensive-scoring (Marlowe-Crowne Denial subscale) university patients showed significantly higher skin-conductance levels and frequency of nonspecific fluctuations than the low anxious-low defensive-scoring subjects. Besides, the conductance values of the low anxious-high defensive-scoring subjects resembled those of the high anxious-low defensive-scoring patients of the clinic for Special Dental Care, the baseline frequency of nonspecific fluctuations excepted. PMID:7808902

  5. Fracture resistance of monolithic zirconia crowns: The importance of the compressive strength of the dental cements used.

    OpenAIRE

    Lægreid, Solveig Jenssen; Nergård, John Magnus

    2014-01-01

    Background: Monolithic zirconia crowns have not been used for a very long period in dentistry even though zirconia with veneering porcelain, as crown and bridge material has been used for several years with great clinical success. Several different luting materials have been purposed for zirconia but concerning monolithic zirconia the knowledge of the influence of the cement seem to be limited. The aim of the study was to investigate three different cements (one phosphate, one self adhesive a...

  6. A retrospective clinical, radiographic and microbiological study of periodontal conditions of teeth with and without crowns Um estudo retrospectivo clínico, radiográfico e microbiológico das condições periodontais de dentes com e sem coroas

    Directory of Open Access Journals (Sweden)

    Marcio Dias Giollo

    2007-12-01

    Full Text Available The aim of this study was to evaluate retrospectively the periodontal conditions of teeth with fixed crowns that had been in place from 3 to 5 years before the study was conducted. Forty individuals were recalled for a follow-up visit. Full-mouth clinical examinations were carried out and Visible Plaque Index (VPI, Gingival Bleeding Index (GBI, Probing Pocket Depth (PPD, and clinical attachment level (CAL were assessed in 6 sites per tooth. Parallel radiographs were also taken and blindly analyzed by a digital caliper (distance between the apex and the bone crest. BANA tests were performed. A contra-lateral sound tooth was considered the control. Mean values were obtained and Wilcoxon and paired sample t tests were used to compare the test and control sites. Crowns had a mean VPI value of 30.42% as compared to 49.17% for sound teeth. The GBI was 33.33% and 26.25% for test and control teeth respectively. Assessment of PPD revealed values of 2.30 and 2.14 mm, and assessment of CAL revealed averages of 2.02 and 1.89 mm for test and control teeth respectively. The mean values for radiographic distances were 12.73 and 13.67 mm, and for the BANA test, 67.50 and 50.00 for sound and crowned teeth, respectively. Statistically significant differences were observed for all parameters except for CAL and for the BANA test. It may be concluded that, with the methods used in the present study, crowns may be associated with more signs of inflammation, however not with periodontal breakdown.O objetivo deste estudo foi avaliar retrospectivamente as condições periodontais de pacientes com coroas fixas colocadas de 3 a 5 anos antes da realização da pesquisa. Quarenta indivíduos foram rechamados. Exames clínicos de toda a boca foram realizados avaliando-se Índice de Placa Visível (IPV, Índice de Sangramento Gengival (ISG, Profundidade de Sondagem (PS e Nível Clínico de Inserção (NCI em 6 sítios por dente. Radiografias paralelas foram obtidas e

  7. A Comparative Evaluation for Biologic Width following Surgical Crown Lengthening Using Gingivectomy and Ostectomy Procedure

    Directory of Open Access Journals (Sweden)

    Kiran Kumar Ganji

    2012-01-01

    Full Text Available Surgical crown lengthening has been proposed as a means of facilitating restorative procedures and preventing injuries in teeth with structurally inadequate clinical crown or exposing tooth structure in the presence of deep, subgingival pathologies which may hamper the access for proper restorative measures. Histological studies utilizing animal models have shown that postoperative crestal resorption allowed reestablishment of the biologic width. However, very little has been done in humans. Aims. The purpose of the study was to evaluate the potential changes in the periodontal tissues, particularly the biologic width, following surgical crown lengthening by two surgical procedures before and after crown placement. Methods and Material. Twenty (20 patients who needed surgical crown lengthening to gain retention necessary for prosthetic treatment and/or to access caries, tooth fracture, or previous prosthetic margins entered the study. The following parameters were obtained from line angles of treated teeth (teeth requiring surgical crown lengthening and adjacent sites: Plaque and Gingival Indices (PI & (GI, Position of Gingival Margin from reference Stent (PGMRS, Probing depth (PD, and Biologic Width (BW. Statistical Analysis Used. Student “t” Test. Results. Initial baseline values of biologic width were 2.55 mm (Gingivectomy procedure B1 Group and 1.95 mm (Ostectomy procedure B2 Group and after surgical procedure the values were 1.15 mm and 1.25 mm. Conclusions. Within the limitations of the study the biologic width, at treated sites, was re-established to its original vertical dimension by 3 months. Ostectomy with apically positioned flap can be considered as a more effective procedure than Gingivectomy for Surgical Crown Lengthening.

  8. Genetic diversity of Trichomonas vaginalis clinical isolates determined by EcoRI restriction fragment length polymorphism of heat-shock protein 70 genes.

    Science.gov (United States)

    Meade, John C; de Mestral, Jacqueline; Stiles, Jonathan K; Secor, W Evan; Finley, Richard W; Cleary, John D; Lushbaugh, William B

    2009-02-01

    Restriction fragment length polymorphism (RFLP) analysis using a multilocus heat-inducible cytoplasmic heat-shock protein 70 (Hsp70) hybridization probe with EcoRI-digested genomic DNA was used in molecular typing of 129 Trichomonas vaginalis isolates. Results indicate that Trichomonas organisms exhibit considerable polymorphism in their Hsp70 RFLP patterns. Analysis of seven American Type Culture Collection reference strains and 122 clinical isolates, including 84 isolates from Jackson, Mississippi, 18 isolates from Atlanta, Georgia, and 20 isolates from throughout the United States, showed 105 distinct Hsp70 RFLP pattern subtypes for Trichomonas. Phylogenetic analysis of the Hsp70 RFLP data showed that the T. vaginalis isolates were organized into two clonal lineages. These results illustrate the substantial genomic diversity present in T. vaginalis and indicate that a large number of genetically distinct Trichomonas isolates may be responsible for human trichomoniasis in the United States. PMID:19190222

  9. Zirconia Crown as Single Unit Tooth Restoration: A Literature Review.

    Science.gov (United States)

    Alfawaz, Yasser

    2016-01-01

    Ceramics has become increasingly popular as a dental restorative material because of its superior esthetics, as well as its inertness and biocompatibility. Among dental ceramics, zirconia is used as a dental biomaterial and it is the material of choice in contemporary restorative dentistry. Zirconia ceramics has both clinical popularity and success due to its outstanding mechanical properties and ease of machining in the green stage via computer-aided design and computer-aided manufacturing technology. Zirconia is one of the most promising restorative biomaterial because it has favorable mechanical and chemical properties suitable for medical application. Zirconia ceramics is becoming a prevalent biomaterial in dentistry. Clinical evaluations also indicate a good success rate for zirconia with minimal complications. This article reviews the current literature on dental zirconia with respect to basic properties, biocompatibility, and clinical applications in aesthetic dentistry as single unit crown. PMID:27443370

  10. BAY 81-8973, a full-length recombinant factor VIII: Human heat shock protein 70 improves the manufacturing process without affecting clinical safety.

    Science.gov (United States)

    Maas Enriquez, Monika; Thrift, John; Garger, Stephen; Katterle, Yvonne

    2016-11-01

    BAY 81-8973 is a full-length, unmodified recombinant human factor VIII (FVIII) approved for the treatment of hemophilia A. BAY 81-8973 has the same amino acid sequence as the currently marketed sucrose-formulated recombinant FVIII (rFVIII-FS) product and is produced using additional advanced manufacturing technologies. One of the key manufacturing advances for BAY 81-8973 is introduction of the gene for human heat shock protein 70 (HSP70) into the rFVIII-FS cell line. HSP70 facilitates proper folding of proteins, enhances cell survival by inhibiting apoptosis, and potentially impacts rFVIII glycosylation. HSP70 expression in the BAY 81-8973 cell line along with other manufacturing advances resulted in a higher-producing cell line and improvements in the pharmacokinetics of the final product as determined in clinical studies. HSP70 protein is not detected in the harvest or in the final BAY 81-8973 product. However, because this is a new process, clinical trial safety assessments included monitoring for anti-HSP70 antibodies. Most patients, across all age groups, had low levels of anti-HSP70 antibodies before exposure to the investigational product. During BAY 81-8973 treatment, 5% of patients had sporadic increases in anti-HSP70 antibody levels above a predefined threshold (cutoff value, 239 ng/mL). No clinical symptoms related to anti-HSP70 antibody development occurred. In conclusion, addition of HSP70 to the BAY 81-8973 cell line is an innovative technology for manufacturing rFVIII aimed at improving protein folding and expression. Improved pharmacokinetics and no effect on safety of BAY 81-8973 were observed in clinical trials in patients with hemophilia A. PMID:27436242

  11. Automated tree crown delineation from imagery based on morphological techniques

    International Nuclear Information System (INIS)

    In current tree crown delineation from imagery, treetops and three dimensional (3D) radiometric shapes of tree crowns are frequently extracted from a spectral band or a brightness component of the image and taken as references to localize and delineate tree crowns. However, color components of the image are rarely used together with the brightness component of the image to facilitate localizing and delineating crowns. The 3D radiometric shape of a crown can be derived from a brightness or color component and may be taken as a half-ellipsoid. From top to bottom of such a half-ellipsoid, multiple horizontal slices can be drawn, contain the treetop, and indicate both the location and the horizontal extent of the crown. Based on such a concept of horizontal slices of crowns, a novel multi-scale method for individual tree crown delineation from imagery was proposed in this study. In this method, the brightness and color components of the image are morphologically opened within the scale range of target crowns, horizontal slices of target crowns are extracted from the resulting opened images and integrated together to localize crowns, and one component is segmented using the watershed approach with reference to the integrated slices. In an experiment on high spatial resolution aerial imagery over natural closed canopy forests, the proposed method correctly delineated approximately 74% of mixedwood tree crowns and 59% of deciduous crowns in the natural forests

  12. Accuracy of Digital Impressions and Fitness of Single Crowns Based on Digital Impressions

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2015-06-01

    Full Text Available In this study, the accuracy (precision and trueness of digital impressions and the fitness of single crowns manufactured based on digital impressions were evaluated. #14-17 epoxy resin dentitions were made, while full-crown preparations of extracted natural teeth were embedded at #16. (1 To assess precision, deviations among repeated scan models made by intraoral scanner TRIOS and MHT and model scanner D700 and inEos were calculated through best-fit algorithm and three-dimensional (3D comparison. Root mean square (RMS and color-coded difference images were offered. (2 To assess trueness, micro computed tomography (micro-CT was used to get the reference model (REF. Deviations between REF and repeated scan models (from (1 were calculated. (3 To assess fitness, single crowns were manufactured based on TRIOS, MHT, D700 and inEos scan models. The adhesive gaps were evaluated under stereomicroscope after cross-sectioned. Digital impressions showed lower precision and better trueness. Except for MHT, the means of RMS for precision were lower than 10 μm. Digital impressions showed better internal fitness. Fitness of single crowns based on digital impressions was up to clinical standard. Digital impressions could be an alternative method for single crowns manufacturing.

  13. EL CROWN HALL. CONTEXTO Y PROYECTO

    Directory of Open Access Journals (Sweden)

    Laura Lizondo Sevilla

    2010-05-01

    Full Text Available RESUMEN El artículo enmarca el edificio del Crown Hall en el contexto docente y arquitectónico de Mies van der Rohe. Revisa sus inicios en la Bauhaus con su primera intervención en un espacio docente para la Bauhaus de Berlín en 1932, así como su marcha a Estados Unidos, los planteamientos arquitectónicos del campus del IIT y el proyecto del Crown Hall. El texto incide en el estudio del proceso proyectual del Crown Hall analizando la evolución de su concepción arquitectónica a través de las diferentes versiones del proyecto. Se constata la transición desde los primeros planteamientos arquitectónicos de los edificios del campus del IIT proyectados por Mies hacia el planteamiento del gran espacio unitario del Crown Hall. Este proyecto se puede entender desde la creciente importancia de la estructura, la claridad constructiva y el manejo del acero y vidrio como únicos materiales de la imagen del edificio y el carácter flexible y unitario del espacio. Finalmente se hace referencia al concepto del "espacio universal" en la arquitectura de Mies, como un concepto abstracto que supera los de flexibilidad de uso o unidad espacial, insinuando, a modo de reflexión, las principales variables que definirían el espacio universal miesiano.SUMMARY The article showcases the Crown Hall building in the educational and architectural context of Mies van der Rohe. It reviews his beginnings in the Bauhaus with his first intervention in an educational space for the Bauhaus of Berlin in 1932, as well as his sojourn to the United States, and the architectural approaches to the IIT campus and the Crown Hall project. The text touches on the study of the planning process for the Crown Hall, analysing the evolution of its architectural conception, through the different versions of the project. The article covers the transition from the first architectural approaches for the IIT campus buildings, planned by Mies, to the approach of the large unitary space of

  14. A Review of the Positive Influence of Crown Contours on Soft-Tissue Esthetics.

    Science.gov (United States)

    Kinsel, Richard P; Pope, Bryan I; Capoferri, Daniele

    2015-05-01

    Successful crown restorations duplicate the natural tooth in hue, chroma, value, maverick colors, and surface texture. Equally important is the visual harmony of the facial and proximal soft-tissue contours, which requires the collaborative skills of the restorative dentist, periodontist, and dental technician. The treatment team must understand the biologic structures adjacent to natural dentition and dental implants. This report describes the potential for specifically designed restorative contours to dictate the optimal gingival profile for tooth-supported and implant-supported crowns. Showing several cases, the article explains how esthetic soft-tissue contours enhance the definitive crown restoration, highlights the importance of clinical evaluation of adjacent biologic structures, and discusses keys to predicting when the proximal papilla has the potential to return to a favorable height and shape. PMID:26053638

  15. 21 CFR 872.3770 - Temporary crown and bridge resin.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3770 Temporary crown and bridge resin. (a... polymethylmethacrylate, intended to make a temporary prosthesis, such as a crown or bridge, for use until a...

  16. Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1994-12-31

    During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.

  17. Clinical results of large defect teeth or flared roots restored by fiber posts and resin composites core in combination with full crowns%纤维桩核冠修复牙体严重缺损的临床效果观察

    Institute of Scientific and Technical Information of China (English)

    王贯新; 白保晶; 魏永杰

    2011-01-01

    目的 观察纤维桩树脂核全冠修复牙体严重缺损和薄弱根管的临床修复效果.方法 选择牙体大面积缺损和薄弱根管患者165例219个患牙为研究对象.患牙经根管治疗后行纤维桩树脂核伞冠修复,修复完成后6个月、1年、2年进行临床复查,其中牙体缺损达龈下行牙龈切除术或冠延长术的患牙,增加修复后1个月和3个月临床复查,评价其临床修复效果.结果 165例的219个患牙中,有4例出现纤维桩与根管壁完整脱落,均未见根折、根裂,重新粘固后未见异常.其余215个患牙修复体未出现脱落,冠边缘密合,牙周正常,219个患牙均未出现基牙松动.结论 应用纤维桩树脂核全冠修复牙体严重缺损和薄弱根管可以达到满意的临床修复效果.%Objective To observe the clinical results of fiber post and resin composite core for the repair of large defect teeth or flared roots. Methods A total of 219 large defect teeth or flared roots from 165 patients were restored by fiber posts and resin composite core as well as full crowns. The clinical results of the restorations were followed up for a minimum of six months. Results Four of the 219 restorations failed but the roots remained intact and re-bonded with the previous post-and-core crowns. The restorations and periodontal tissues of the other 215 teeth were normal and successful. Conclusion Fiber post and resin composite core system is reliable for restoring large defect teeth or flared roots with satisfactory clinical results.

  18. Fracture resistance of monolithic zirconia molar crowns with reduced thickness

    OpenAIRE

    Nakamura, Keisuke; Harada, A.; Inagaki, R.; Kanno, Taro; Niwano, Y; Milleding, Percy; Ørtengren, Ulf Thore

    2015-01-01

    Objectives. The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness, and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. Materials and methods. Monolithic zirconia crowns (Lava Plus Zirconia, 3M/ESPE) with specified axial/occlusal thicknesses and lithium disilica...

  19. Finkelstein Reaction in Functionalized Crown-ether Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    Xiao Hua WANG; Han Zhi WANG; Hui LIU; Yuan KOU

    2006-01-01

    Functional crown-ether ionic liquids were used as catalytic green solvents of Finkelstein reaction of 1-bromooctane and iodide. The rate and yield of the reaction were obvious improved compared with that using crown ether in water. No free crown ether loss was observed after reaction.

  20. Cambios dimensionales de los tejidos en los procedimientos de alargamiento coronario Dimensional changes in tissues after crown lengthening procedures

    Directory of Open Access Journals (Sweden)

    C. Álvarez-Novoa García

    2012-08-01

    : We performed a search in PubMed with the keyword "crown lengthening", limited to English language articles, that were published between the years 1990-2009, which were clinical trials. The recovery of documents was held in the periodicals of the Faculty of Dentistry in UCM, and in Compludoc database. Two evaluators reviewed the papers individually. Results and Discussion: The seven articles, including studies in both animals and humans, which were included in the review, analyzing gingival index, bone level, probing depth, attachment level and biological width, and crown length and the position of the gingival margin. Conclusions: Bone level is altered during the first 3 months, but thereafter remains constant. The longer-term studies found no significant differences in bone probing depth at 6 and 12 months after the surgery.

  1. Recommendations for conducting controlled clinical studies of dental restorative materials. Science Committee Project 2/98--FDI World Dental Federation study design (Part I) and criteria for evaluation (Part II) of direct and indirect restorations including onlays and partial crowns.

    Science.gov (United States)

    Hickel, Reinhard; Roulet, Jean-François; Bayne, Stephen; Heintze, Siegward D; Mjör, Ivar A; Peters, Mathilde; Rousson, Valentin; Randall, Ros; Schmalz, Gottfried; Tyas, Martin; Vanherle, Guido

    2007-01-01

    About 35 years ago, Ryge provided a practical approach to the evaluation of the clinical performance of restorative materials. This systematic approach was soon universally accepted. While that methodology has served us well, a large number of scientific methodologies and more detailed questions have arisen that require more rigor. Current restorative materials have vastly improved clinical performance, and any changes over time are not easily detected by the limited sensitivity of the Ryge criteria in short-term clinical investigations. However, the clinical evaluation of restorations not only involves the restorative material per se but also different operative techniques. For instance, a composite resin may show good longevity data when applied in conventional cavities but not in modified operative approaches. Insensitivity, combined with the continually evolving and nonstandard investigator modifications of the categories, scales, and reporting methods, has created a body of literature that is extremely difficult to interpret meaningfully. In many cases, the insensitivity of the original Ryge methods leads to misinterpretation as good clinical performance. While there are many good features of the original system, it is now time to move on to a more contemporary one. The current review approaches this challenge in two ways: (1) a proposal for a modern clinical testing protocol for controlled clinical trials, and (2) an in-depth discussion of relevant clinical evaluation parameters, providing 84 references that are primarily related to issues or problems for clinical research trials. Together, these two parts offer a standard for the clinical testing of restorative materials/procedures and provide significant guidance for research teams in the design and conduct of contemporary clinical trials. Part 1 of the review considers the recruitment of subjects, restorations per subject, clinical events, validity versus bias, legal and regulatory aspects, rationales for

  2. Mathematical Modelling of Running Crown Forest Fires

    OpenAIRE

    Taranchuk, V. B.; Barovik, D. V.

    2010-01-01

    Adapted mathematical model of running crown forest fire propagation is considered. Simplifying assumptions, equations of the model, initial and boundary conditions, finite diference approximations are introduced. The results of computer modelling and the peculiarities of forest fire behavior in heterogeneous forests are discussed

  3. Aspergillosis in a red-crowned crane

    Science.gov (United States)

    Stroud, R.K.; Duncan, R.M.

    1983-01-01

    An unusual form of pulmonary aspergillosis in a red-crowned crane (Grus japonensis) is described in this report. The major lesion is unique because it closely resembles a lesion referred to as an aspergilloma. An aspergilloma is a single large granulomatous lesion that resembles a tumor and is caused by fungi of the genus Aspergillus.

  4. Everbearing strawberry cultivars - susceptibility to crown rot

    OpenAIRE

    Parikka, Päivi; Karhu, Saila; Hietaranta, Tarja

    2009-01-01

    Studies on the production of everbearing strawberry cultivars were started at MTT Plant Production Research in 2007. MTT Horticulture makes trials in tunnel and open fields to study the growth, yield and overwintering of cultivars in northern conditions. Resistance to crown rot is also being tested.

  5. Internal adaptation of cast titanium crowns

    Directory of Open Access Journals (Sweden)

    Sicknan Soares da Rocha

    2007-08-01

    Full Text Available As the adaptation of titanium crowns obtained by Rematitan Plus investment, specific for titanium, is not recognized to be suitable, this study evaluated the effect of the concentration of the specific liquid and the temperature of the mold of investments on the internal misfit of crowns cast on commercially pure titanium. Individual dies of epoxy resin were obtained, representing teeth prepared for full-crown restoration with a 6-degree axial surface convergence angle and shoulder (1.0 mm. For the waxing of each crown, a ring-shaped stainless steel matrix (8.0mm internal diameter; 7.5 mm height was adapted above the individual dies of epoxy resin. The Rematian Plus investment was mixed according to the manufacturer's instructions using two different concentrations of the specific liquid: 100%, 75%. Casting was performed in a Discovery Plasma Ar-arc vacuum-pressure casting machine with molds at temperatures of 430ºC, 515ºC and 600ºC. The crowns were cleaned individually in a solution (1% HF + 13% HNO3 for 10 min using a ultrasonic cleaner, with no internal adaptations, and luted with zinc phosphate cement under a 5 kg static load. The crown and die assemblies were embedded in resin and sectioned longitudinally. The area occupied by cement was observed using stereoscopic lens (10X and measured by the Leica Qwin image analysis system (mm². The data for each experimental condition (n=8 were analyzed by Kruskal-Wallis non-parametric test (á=0.05. The results showed that liquid dilution and the increase in mold temperature did not significantly influence the levels of internal fit of the cast titanium crowns. The lowest means (±SD of internal misfit were obtained for the 430ºC/100%: (7.25 mm² ±1.59 and 600ºC/100% (8.8 mm² ±2.25 groups, which presented statistically similar levels of internal misfit.

  6. Solvent Effects on Cesium Complexation with Crown Ethers from Liquid to Supercritical Fluids

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) techniques were used to study crown ether-water interactions in solvents of low dielectric constants such as chloroform and carbon tetrachloride. Water forms a 1:1 complex with a number of crown ethers including 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18=crown-6, dicyclohexano-24-crown 8, and dibenzl-24-crown-8 in chloroform. Among these crown ethers, the 18-crown-6-H2 complex has the largest equilibrium constant (K=545) and 97% of the crown is complexed to water in chloroform. Addition of carbon tetrachloride to chloroform lowers the equilibrium constants of the crown-water complexes. The partition coefficients of crown ethers (D=crown in water/crown in solvent) between water and organic solvent also vary with solvent composition

  7. Branch architecture, light interception and crown development in saplings of a plagiotropically branching tropical tree, Polyalthia jenkinsii (Annonaceae).

    Science.gov (United States)

    Osada, Noriyuki; Takeda, Hiroshi

    2003-01-01

    To investigate crown development patterns, branch architecture, branch-level light interception, and leaf and branch dynamics were studied in saplings of a plagiotropically branching tree species, Polyalthia jenkinsii Hk. f. & Thoms. (Annonaceae) in a Malaysian rain forest. Lengths of branches and parts of the branches lacking leaves ('bare' branches) were smaller in upper branches than in lower branches within crowns, whereas lengths of 'leafy' parts and the number of leaves per branch were larger in intermediate than in upper and lower branches. Maximum diffuse light absorption (DLA) of individual leaves was not related to sapling height or branch position within crowns, whereas minimum DLA was lower in tall saplings. Accordingly, branch-level light interception was higher in intermediate than in upper and lower branches. The leaf production rate was higher and leaf loss rate was smaller in upper than in intermediate and lower branches. Moreover, the branch production rate of new first-order branches was larger in the upper crowns. Thus, leaf and branch dynamics do not correspond to branch-level light interception in the different canopy zones. As a result of architectural constraints, branches at different vertical positions experience predictable light microenvironments in plagiotropic species. Accordingly, this pattern of carbon allocation among branches might be particularly important for growth and crown development in plagiotropic species. PMID:12495920

  8. Elliptic Fourier analysis of crown shapes in Quercus petraea trees

    Directory of Open Access Journals (Sweden)

    Ovidiu Hâruţa

    2011-06-01

    Full Text Available Shape is a fundamental morphological descriptor, significant in taxonomic research as well as in ecomorphology, one method of estimation being from digitally processed images. In the present study, were analysed shapes of Q. petraea crowns, pertaining to five different stem diameter classes, from three similar stands. Based on measurements on terrestrial digital vertical photos, crown size analysis was performed and correlations between crown and stem variables were tested. Linear regression equations between crown volumes and dbh, and crown volumes and stem volumes were derived, explaining more than half of data variability. Employment of elliptic Fourier analysis (EFA, a powerful analysis tool, permitted the extraction of the mean shape from crowns, characterized by high morphological variability. The extracted, most important, coefficients were used to reconstruct the average shape of the crowns, using Inverse Fourier Transform. A mean shape of the crown, corresponding to stand conditions in which competition is added as influential shaping factor, aside genetic program of the species, is described for each stem diameter class. Crown regions with highest shape variability, from the perspective of stage development of the trees, were determined. Accordingly, the main crown shape characteristics are: crown elongation, centroid position, asymmetry with regard to the main axis, lateral regions symmetrical and asymmetrical variations. 

  9. Elliptic Fourier analysis of crown shapes in Quercus petraea trees

    Directory of Open Access Journals (Sweden)

    Ovidiu Hâruţa

    2011-02-01

    Full Text Available Shape is a fundamental morphological descriptor, significant in taxonomic research as well as in ecomorphology, one method of estimation being from digitally processed images. In the present study, were analysed shapes of Q. petraea crowns, pertaining to five different stem diameter classes, from three similar stands. Based on measurements on terrestrial digital vertical photos, crown size analysis was performed and correlations between crown and stem variables were tested. Linear regression equations between crown volumes and dbh, and crown volumes and stem volumes were derived, explaining more than half of data variability. Employment of elliptic Fourier analysis (EFA, a powerful analysis tool, permitted the extraction of the mean shape from crowns, characterized by high morphological variability. The extracted, most important, coefficients were used to reconstruct the average shape of the crowns, using Inverse Fourier Transform. A mean shape of the crown, corresponding to stand conditions in which competition is added as influential shaping factor, aside genetic program of the species, is described for each stem diameter class. Crown regions with highest shape variability, from the perspective of stage developmentof the trees, were determined. Accordingly, the main crown shape characteristics are: crown elongation, mass center, asymmetry with regard to the main axis, lateral regions symmetrical and asymmetrical variations.

  10. Comparative study on the microbial adhesion to preveneered and stainless steel crowns

    Directory of Open Access Journals (Sweden)

    Waleed M Bin AlShaibah

    2012-01-01

    Full Text Available Context: The extensive plaque formation on dental restorations may contribute to secondary caries or periodontal inflammation. Therefore, it is important to know how different types of dental restorations may prevent or promote the accumulation of microorganisms. Aims: The aim of this in vivo study was to evaluate the adhesion of Streptococcus mutans to preveneered and stainless steel crowns (SSCs and to evaluate the effects of these restorations on the gingival health and oral hygiene. Materials and Methods: Twenty patients (age 3-5 years were selected from the outpatient clinic of the pedodontics department, Faculty of Oral and Dental Medicine, Cairo University. The selected patients had (dmf index for primary dentition ≤4, including lower right and left first primary molars. Each tooth was pulpotomy-treated and restored with either type of crowns (split-mouth technique. Then, ten swabs from the buccal mucosa, preveneered crown, and SSC surfaces were taken from each patient. Also, the gingival index (GI and oral hygiene index (OHI-S were measured at different times during the study. Mitis Salivarius Bacitracin agar (MSBA was used as a selective medium for S. mutans growth. MSBA plates were taken in candle jar and incubated aerobically in 37°C for 48 h. Finally, bacteria were counted and expressed in colony forming unit (CFU. Results: After 1, 2, and 4 weeks, mucosa and crown swabs of preveneered crown showed statistically significant higher mean CFU counts than SSC. Through the whole study period, the two restorations revealed a statistically significant decrease in mean CFU counts. Also, there was a statistically significant positive (direct correlation between OHI-S, GI, and S. mutans counts on both restorations. Conclusions: The adhesion of S. mutans to preveneered crowns was higher than to SSC. Full mouth rehabilitation led to significant decrease in S. mutans count in the short term. An increase in S. mutans counts is associated with

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

    Science.gov (United States)

    Unal, Server Mutluay; Yurekli, Emel; Güven, Sedat

    2016-01-01

    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. PMID:27141257

  12. Clinically Significant Contrast Induced Acute Kidney Injury after Non-Emergent Cardiac Catheterization - Risk Factors and Impact on Length of Hospital Stay

    International Nuclear Information System (INIS)

    Objective: To evaluate the frequency and risk factors associated with clinically significant contrast-induced nephropathy (CIN) in patients undergoing non-emergent coronary angiography. Study Design: Descriptive study. Place and Duration of Study: The Aga Khan University Hospital, Karachi, from January 2005 to December 2007. Methodology: Case records of patients who underwent coronary angiography with a serum creatinine of >= 1.5 mg/dl at the time of procedure were evaluated. Clinically significant contrast induced nephropathy (CSCIN) was defined as either doubling of serum creatinine from baseline value within a week following the procedure or need for emergency hemodialysis after the procedure. Results: One hundred and sixteen patients met the inclusion criteria. Mean age was 64.0 +- 11.5 years, 72% were males. Overall prevalence of CIN was 17% (rise of serum creatinine by A= 0.5 mg/dl) while that of clinically significant CIN (CSCIN) was 9.5% (11 patients). Patients with CSCIN had significantly lower left ventricular ejection fraction (p = 0.03, OR: 0.24; 95% CI = 0.06 A= 0.91) and higher prevalence of cerebrovascular disease (p < 0.001, OR: 14.66; 95% CI = 3.30 - 65.08). Mean baseline serum creatinine was significantly higher, 3.0 +- 1.5 vs. 2.0 +- 1.1 mg/dl (p = 0.03, OR: 1.47; 95% CI = 1.03 - 2.11) whereas mean GFR estimated by Cockcroft-Gault formula was significantly lower at 25 +- 7.4 vs. 41.0 +- 14.6 ml/minute (p = 0.001, OR = 0.89, 95% CI = 0.84 A= 0.95) at the time of procedure in patients with CSCIN. Mean length of hospital stay was significantly higher in this group compared to those without CIN, 9.0 +- 5.1 vs. 3.0 +- 3.2 days (p = 0.001, OR = 1.31, 95% CI = 1.12 - 1.54). Multivariate analysis revealed low GFR (p = 0.001, OR = 0.88; 95% CI = 0.82 - 0.95) and low ejection fraction (p = 0.03, OR = 0.20; 95% CI = 0.04 - 0.91) to be independent factors associated with CSCIN. No significant differences were noted between the two groups in patients with

  13. COMPLEX EVALUATION OF THE PERIODONTAL CONDITION IN TEETH WITH AND WITHOUT CERAMIC CROWNS

    Directory of Open Access Journals (Sweden)

    M.A. DINU

    2013-12-01

    Full Text Available The scope of the study was a retrospective evaluation, involving a 1-3 year follow-up period, of the periodontal condition of teeth with fixed crowns. The experimental group was formed of 40 patients having followed a prosthetic treatment with ceramic crowns. The complete clinical evaluations performed included analysis of the plaque index (IP, of the index of gingival bleeding (ISG, probing of the depth of the perio‑ dontal pockets (AP and of the level of clinical attachment (AC. All these parameters were evaluated in 6 different sites of each tooth. Panoramic radiographies, on which the height of the alveolar crest was analyzed, were also taken. The mean values were obtained with the Wilcoxon statis‑ tical tests and with test t, which permitted a comparative evaluation of both test and control sites. The teeth on which ceramic crowns had been applied had a mean value of the plaque index, IP, of 53.17% com‑ paratively with 58.24% - the value recorded in the control teeth. The index of gingival bleeding, ISG, was 38.79% and 29.16% for the test and, respectively, control teeth. Evalu‑ ation of the depth of the periodontal pockets, AP, eviden‑ ced mean values of 2.80 and, respectively, 2.30 mm, while the mean values registered for the level of clinical attach‑ ment, AC, were of 2.05 and 2.49 mm for the test and, respectively, control teeth. The mean values for the heigth of the alveolar bone, evaluated radiographically, were of 13.01 for the teeth with ceramic crowns, and of 13.96 mm, respectively, for the control teeth. The conclusion of the study, based on the results obtai‑ ned, is that teeth with ceramic crowns may frequently show signs of inflammation, yet not necessarily accompa‑ nied by irreversible destruction of the periodontal tissue.

  14. Does Crown Financial Portfolio Composition Matter?

    OpenAIRE

    Nick Davis

    2001-01-01

    This paper considers Crown financial portfolio composition from a welfare perspective. It argues that a broad definition of the Crown’s portfolio is required for analysing the welfare implications of portfolio composition. In practice, this means incorporating the present discounted value of tax and expenditure flows as well as traditional measures of assets and liabilities. Financial portfolio composition affects welfare for a number of reasons: imperfect and incomplete markets; distortionar...

  15. Adsorption of rare earths with crown ether adsorbents

    International Nuclear Information System (INIS)

    Crown ether - phosphotungstic acid (PW) and crown ether -phosphomolybdic acid (PMo) precipitates, and also the granular entrapped crown ether - PMo (or PW) in polyacrylamide, were prepared and applied as adsorbents for rare earth metal ions. Adsorbents containing 15-crown-5, such as 15-crown-5 - PMo, were better adsorbents than the other crown ether precipitates. The adsorption capacity of 15-crown-5 - PMo for Eu3+ was determined and corresponded to about 0.166 mmol of Eu3+ per gram of the absorbent. The effects of pH and metal ion concentration on adsorption were also investigated. Crown ether - PMo (or PW) precipitates underwent hydrolysis at pH >= 1, but the granular entrapped crown ether - PMo (or PW) - polyacrylamide adsorbents were not hydrolysed at pH >= 1. The adsorption of individual rare earth ions with 15-crown-5 - PMo - polyacrylamide showed that Tb3+, Nd3+, Eu3+ and Gd3+ were readily adsorbed, but adsorption was difficult for Ce4+, Sm3+ and Dy3+. (author)

  16. Clinical impact of antimicrobial resistance in European hospitals: excess mortality and length of hospital stay related to methicillin-resistant Staphylococcus aureus bloodstream infections.

    LENUS (Irish Health Repository)

    de Kraker, Marlieke E A

    2011-04-01

    Antimicrobial resistance is threatening the successful management of nosocomial infections worldwide. Despite the therapeutic limitations imposed by methicillin-resistant Staphylococcus aureus (MRSA), its clinical impact is still debated. The objective of this study was to estimate the excess mortality and length of hospital stay (LOS) associated with MRSA bloodstream infections (BSI) in European hospitals. Between July 2007 and June 2008, a multicenter, prospective, parallel matched-cohort study was carried out in 13 tertiary care hospitals in as many European countries. Cohort I consisted of patients with MRSA BSI and cohort II of patients with methicillin-susceptible S. aureus (MSSA) BSI. The patients in both cohorts were matched for LOS prior to the onset of BSI with patients free of the respective BSI. Cohort I consisted of 248 MRSA patients and 453 controls and cohort II of 618 MSSA patients and 1,170 controls. Compared to the controls, MRSA patients had higher 30-day mortality (adjusted odds ratio [aOR] = 4.4) and higher hospital mortality (adjusted hazard ratio [aHR] = 3.5). Their excess LOS was 9.2 days. MSSA patients also had higher 30-day (aOR = 2.4) and hospital (aHR = 3.1) mortality and an excess LOS of 8.6 days. When the outcomes from the two cohorts were compared, an effect attributable to methicillin resistance was found for 30-day mortality (OR = 1.8; P = 0.04), but not for hospital mortality (HR = 1.1; P = 0.63) or LOS (difference = 0.6 days; P = 0.96). Irrespective of methicillin susceptibility, S. aureus BSI has a significant impact on morbidity and mortality. In addition, MRSA BSI leads to a fatal outcome more frequently than MSSA BSI. Infection control efforts in hospitals should aim to contain infections caused by both resistant and susceptible S. aureus.

  17. An analysis of clinical activity, admission rates, length of hospital stay, and economic impact after a temporary loss of 50% of the non-operative podiatrists from a tertiary specialist foot clinic in the United Kingdom

    Directory of Open Access Journals (Sweden)

    Catherine Gooday

    2013-09-01

    Full Text Available Introduction: Podiatrists form an integral part of the multidisciplinary foot team in the treatment of diabetic foot–related complications. A set of unforeseen circumstances within our specialist diabetes foot service in the United Kingdom caused a loss of 50% of our non-operative podiatry team for almost 7 months during 2010. Some of this time was filled by non-specialist community non-operative podiatrists. Methods: We assessed the economic impact of this loss by examining data for the 5 years prior to this 7-month interruption, and for the 2 years after ‘normal service’ was resumed. Results: Our data show that the loss of the non-operative podiatrists led to a significant rise in the numbers of admissions into hospital, and hospital length of stay also increased. At our institution a single bed day cost is £275. During the time that the numbers of specialist non-operative podiatry staff were depleted, and for up to 6 months after they returned to normal activities, the extra costs increased by just less than £90,000. The number of people admitted directly from specialist vascular and orthopaedic clinics is likely to have increased due to the lack of capacity to manage them in the diabetic foot clinic. Our data were unable to assess these individuals and did not look at the costs saved from avoiding surgery. Thus the actual costs incurred are likely to be higher. Conclusions: Our data suggest that specialist non-operative podiatrists involved in the treatment of the diabetic foot may prevent unwarranted hospital admission and increased hospitalisation rates by providing skilled assessment and care in the outpatient clinical settings.

  18. Winter habitat selection of red-crowned crane (Grus japonensis)

    Institute of Scientific and Technical Information of China (English)

    张洪海; 杨月伟

    2000-01-01

    This paper studied the winter habitat selection of red-crowned cranes (Grus japonensis) in Yancheng National Natural Reserve, Jiangsu Province. There were six types of habitat used by red-crowned cranes, i.e. salt-works, aquiculture ponds, reed lands, grassy tidal lands, salting wormwood lands and wheat fields. The wheat field was a new type of habitat used by red-crowned cranes. More than 70 percent of red-crowned cranes chose grassy tidal lands, salting wormwood lands, and reed lands as their most important habitats. In recent years, the distribution of red-crowned cranes moved southward gradually. Red-crowned cranes prefer artificial or semi-artificial wetlands rather than original wetlands, successive distribution was broken into fragments.

  19. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    further reduced with another piston crown where eight cylindrical volumes were drilled into the piston crown, so that the cylinder liner was not exposed directly to the combustion. A configuration with seven hemispherical volumes was less silent in operation, but still better than the flat piston crown......Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter...... compression volume into four smaller volumes placed between the perimeter of the piston and the cylinder liner increased the noise to a higher level than that generated with a flat piston crown. This was due to resonance between the four volumes. Using eight volumes instead decreased the noise. The noise was...

  20. Elliptic Fourier analysis of crown shapes in Quercus petraea trees

    OpenAIRE

    Ovidiu Hâruţa

    2011-01-01

    Shape is a fundamental morphological descriptor, significant in taxonomic research as well as in ecomorphology, one method of estimation being from digitally processed images. In the present study, were analysed shapes of Q. petraea crowns, pertaining to five different stem diameter classes, from three similar stands. Based on measurements on terrestrial digital vertical photos, crown size analysis was performed and correlations between crown and stem variables were tested. Linear regression ...

  1. Two Mathematical Models for Generation of Crowned Tooth Surface

    OpenAIRE

    Laszlo Kelemen; Jozsef Szente

    2014-01-01

    Gear couplings are mechanical components to connect shaft ends and eliminate the misalignments. The most important element of the gear coupling is the hub which is an external gear having crowned teeth. The crowned teeth on the hub are typically produced by hobbing. The resulting tooth surface depends on several parameters. It is influenced by the size of the hob and the feed. In this paper two mathematical models of the crowned tooth surface are introduced for the generation of the idealized...

  2. The reparation of residual roots and residual crowns and masticatory function%残根和残冠的修复与咀嚼功能

    Institute of Scientific and Technical Information of China (English)

    张俊杰

    2002-01-01

    @@ 1 The evidences of the reparation of residual roots and residual crowns and the clinical significances Lots of patients have severe physical and mental pain and life quality decrease resulted from the extraction of residual roots and residual crowns. With science development, new material application and designing method promotion, several artificial teeth have replaced the extraction of teeth. In some degree, the method have relieved the pain of no teeth.

  3. Referential haematocrite, haemoglobin, glucose and electrolyte values for Yellow-crowned Amazon (Amazona ochrocephala (Gmelin, 1788)) kept in captivity in Ibagué

    OpenAIRE

    Fabián E Castañeda; Edwin F Buriticá-Gaviria; Lady J Cruz

    2012-01-01

    The Yellow-crowned Amazon or Yellow-crowned Parrot (Amazona ochrocephala) is found from Panama to northern Bolivia and western Brazil; it is the most widely distributed parrot in Colombia and one of the most illegally trafficked ones Basic aspects regarding clinical pathology, haematology and blood biochemistry have usually been used in diagnosing sick birds; however, physiologic parameters should be studied to ascertain normal parameters, bearingeach region’spertinent variables and their r...

  4. Basal ganglia - thalamus and the crowning enigma

    Directory of Open Access Journals (Sweden)

    Marianela eGarcia-Munoz

    2015-11-01

    Full Text Available When Hubel (1982 referred to layer 1 of primary visual cortex as …a ‘crowning mystery’ to keep area-17 physiologists busy for years to come... he could have been talking about any cortical area. In the 80’s and 90’s there were no methods to examine this neuropile on the surface of the cortex: a tangled web of axons and dendrites from a variety of different places with unknown specificities and doubtful connections to the cortical output neurons some hundreds of microns below. Recently, three changes have made the crowning enigma less of an impossible mission: the clear presence of neurons in layer 1 (L1, the active conduction of voltage along apical dendrites and optogenetic methods that might allow us to look at one source of input at a time. For all of those reasons alone, it seems it is time to take seriously the function of L1. The functional properties of this layer will need to wait for more experiments but already L1 cells are GAD67 positive, i.e., inhibitory! They could reverse the sign of the thalamic glutamate (GLU input for the entire cortex. It is at least possible that in the near future normal activity of individual sources of L1 could be detected using genetic tools. We are at the outset of important times in the exploration of thalamic functions and perhaps the solution to the crowning enigma is within sight. Our review looks forward to that solution from the solid basis of the anatomy of the basal ganglia output to motor thalamus. We will focus on L1, its afferents, intrinsic neurons and its influence on responses of pyramidal neurons in layers 2/3 and 5. Since L1 is present in the whole cortex we will provide a general overview considering evidence mainly from the somatosensory cortex before focusing on motor cortex.

  5. Aesthetic treatment on anterior teeth crown fracture caused by dental trauma

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2012-12-01

    Full Text Available Background: Complicated crown fracture is a tooth fracture that involve enamel, dentine and pulp. The incidence of complicated crown fracture ranges from 2% to 13% of all dental injuries and the most commonly involved teeth are the maxillary central incisors. Various treatment modalities are available depending on the clinical, physiological and radiographic examination of the involved teeth. Purpose: The aim of this case report is to present the management of crown fractures with pulpal exposure caused by traumatic injury, through endorestoration approach to reconstruct the shape and function of the teeth. Case: A 17 years old male with complicated crown fractures of anterior teeth #11 #21 and #22. The patient wish for aesthetic dental treatment in both of its form and function. Case management: Crown fractures of anterior teeth with exposed pulp caused by traumatic injury were reconstructed by endorestoration approach. The endodontic treatment with post and core insertion in the root canal which will increase its retention and porcelain fused to metal crown which will aesthetically recover its original form and function. After restoration the patient feel very glad and confident with the result. Conclusion: Endorestoration treatment on anterior teeth with complicated crown fractures and exposed pulp is able to recover the normal form, function and dental aesthetic in accordance with stomatognatic system and self confidence.Latar belakang: Fraktur mahkota kompleks (complicated adalah fraktur pada mahkota gigi yang melibatkan enamel, dentin dan pulpa. Kejadian dari fraktur mahkota kompleks bervariasi antara 2-13% dari semua trauma gigi dan sebagian besar gigi yang terkena adalah gigi insisif pertama rahang atas. Berbagai macam cara perawatan yang dilakukan tergantung pada hasil pemeriksaan klinis, psikologis dan radiografis dari gigi yang terkena. Tujuan: Laporan kasus ini menjelaskan penatalaksanaan fraktur mahkota gigi dengan pulpa terbuka

  6. Simplified Fabrication of an Esthetic Implant-Supported Crown With a Novel CAD/CAM Glass Ceramic.

    Science.gov (United States)

    Conejo, Julián; Blatz, Markus B

    2016-06-01

    Implant therapy and CAD/CAM technologies are advancing quickly, providing predictable esthetic and functional treatment options. A recent development involves the use of zirconia-reinforced lithium-silicate ceramic for fabrication of implant-supported restorations. Suitable for monolithic crowns, the material provides the optical advantages of a silicate ceramic with improved physical strength. Several prerequisites, however, are necessary to fabricate screw-retained monolithic restorations in the anterior maxilla. This case report demonstrates the clinical steps to fabricate a monolithic ceramic CAD/CAM crown on an immediately placed dental implant in the esthetic zone. PMID:27517477

  7. Multidisciplinary approach for the treatment of a complicated crown-root fracture in a young patient: a case report.

    Science.gov (United States)

    de Castro, José Carlos Monteiro; Poi, Wilson Roberto; Pedrini, Denise; Tiveron, Adelisa Rodolfo Ferreira; Brandini, Daniela Atili; de Castro, Mara Antônio Monteiro

    2011-10-01

    Crown-root fractures in permanent teeth cause esthetic and functional problems. This paper reports the case of a complicated crown-root fracture in the maxillary right central incisor of a young patient who was treated with a multidisciplinary approach in two phases. A modified Widman flap, root canal therapy, glass fiber post cementation, and adhesive tooth fragment reattachment were performed shortly after an accident. Satisfactory esthetic and functional outcomes were obtained. However, the patient did not attend follow-up visits and returned after 7 years. During this second phase, the clinical and radiographic examination showed stability and adaptation of the fragment and good periodontal health conditions, but crown darkening and a radiolucent image associated with the root apex of the fractured tooth were also observed. The periapical lesion was surgically removed by apicoectomy, and the esthetics were recovered with a direct composite resin veneer on the traumatized tooth. PMID:21909497

  8. Estimating canine tooth crown height in early Australopithecus.

    Science.gov (United States)

    Plavcan, J Michael; Ward, Carol V; Paulus, Faydre L

    2009-07-01

    Canine tooth size reduction and the associated reduction in canine dimorphism is a basal hominin character that also provides important evidence for models of behavioral evolution. Two specimens of Australopithecus anamensis (KNM-KP 29287 and KNM-KP 29283) that do not preserve the canine crown, but do preserve the root or alveolus, appear to suggest that canine size variation and canine dimorphism in this species may have been greater than in other hominins. We evaluate canine root and crown dimensions in a series of extant hominoids, and estimate canine crown height in Australopithecus afarensis and A. anamensis. Our results demonstrate that it is possible to generate estimates of canine crown height from basal canine crown and root dimensions with a moderate degree of accuracy. Estimates of maxillary canine crown size for A. anamensis are slightly larger than those of A. afarensis, and are approximately the same size as canines of modern female chimpanzees. Estimated mandibular canine crown height is very similar in the two species. Variation within the A. anamensis sample of estimated canine crown heights is similar to that of modern humans, suggesting a low degree of sexual dimorphism. Inclusion of estimates for KNM-KP 29287 and KNM-KP 29283 does not substantially increase either the estimate of overall canine size or variation for A. anamensis. PMID:19482334

  9. Metal ion complexation by ionizable crown ethers: Progress report, January 1, 1985-December 31, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, R.A.

    1987-06-01

    A variety of lipophilic crown ethers with pendant ionizable groups has been prepared. Several lipophilic acyclic polyethers bearing either one or two ionizable groups have also been synthesized. Complexation of alkali metal and alkaline earth cations by such novel ligands has been probed using NMR and solvent extraction. Effects of ring size, side arm length, ionizable group identity and other structural variations, as well as the effect of the solvent, the competitive alkali metal cation solvent extraction has been assessed. Investigations of heavy metal and transition metal cation complexation by ionizable crown ethers have been conducted. The influence of structural variations within acyclic polyether carboxylic acids and dicarboxylic acids on the alkali metal and alkaline earth cation solvent extraction has also been probed. New ligands have been developed which exhibit high selectivities for Cs/sup +/ and Ra/sup 2 +/ in solvent extraction processes. The ability of ionizable crown ethers to function as selective metal cation carriers in liquid membrane transport processes has been examined in both bulk liquid membrane and polymer-supported liquid membrane transport systems.

  10. Calorimetric study of binding of some disaccharides with crown ethers

    International Nuclear Information System (INIS)

    Isothermal titration calorimetry has been applied to the determination of the thermodynamic parameters of binding of β-lactose, α,α-trehalose and sucrose with 15-crown-5 and 18-crown-6 in water at 298.15 K. The formation of 1:1 molecular associates has been found for the systems studied except 18-crown-6 and β-lactose. The associates are preferentially or completely entropy stabilized. The most stable associate is formed between α,α-trehalose and 18-crown-6. The obtained values of thermodynamic parameters of binding are discussed from the point of view of solute-solvent interactions as well as conformational and structural peculiarities of the disaccharides (DS) and crown ethers (CE)

  11. An interdisciplinary approach to treat crown-root-fractured tooth

    Directory of Open Access Journals (Sweden)

    Ying Chun Sun

    2013-01-01

    Full Text Available Restoration of a crown-root subgingival fractured tooth, especially at anterior aesthetic zones is still a great challenge for restorative dentists. Crown lengthening procedure alone has the disadvantage of high gingival curve of the final restoration, which was not discontinuous to adjacent teeth and thus compromise cosmetic outcomes. The objective of this report is to display a new interdisciplinary approach which combining endodontic root canal treatment, orthodontic extrusion, periodontal crown lengthening surgery and prosthodontic post-core-crown restoration procedures to restore a crown-root subgingival fractured maxillary central incisor and achieved a satisfied cosmetic result. Computer-based spectrophotometer was also used to accurately select colour without objective interference to achieve ideal cosmetic effects.

  12. Using 15-crown-5, 18-crown-6 and dicyclohexano-18-crown-6 for Am, Ce, Eu and Cm extraction from acid solutions

    International Nuclear Information System (INIS)

    The extraction from nitric acid of Am, Eu, Ce, Cm(III) tracers by 15-crown-5 (15C5), 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DCH18C6) as well as mixtures of crown ethers and chlorinated cobalt dicarbollide (ChCoD) in nitrobenzene solutions has been investigated. It was revealed that 18C6 is selective for Ce, Am and Cm compared with Eu. The addition of 18C6 to a solution of ChCoD allows Am and Cm to be separated from lanthanides by using this extractant more efficiently. The separation factors of Ce, Am, Cm and Eu are increased as a function of the ionic strength of the aqueous phase for extraction by mixtures of 18C6 and ChCoD and of DCH18C6 and ChCoD

  13. The cascade test of removing Sr from simulated HLLW by crown ether dicyclohexano-18-crown-6

    International Nuclear Information System (INIS)

    The remaining radioactive species in HLLW after actinides removal are mainly 90Sr and 137Cs. The further removal of these two nuclides will transform HLLW into intermediate or low-level liquid waste. In this work, the inactive cascade test is performed for Sr removal with crown ether dicyclohexano-18-crown-6 (DCH18C6) from the simulated HLLW from which actinides have been removed by TRPO process. The simulated HLLW, adding 3.4 times dilution, is used as feed solution in which the HNO3 concentration is adjusted to 1.0 mol/l. The whole process consists of 10 extraction, 2 scrubbing and 4 stripping stages. The removing ratio of Sr is more than 98.7%. The profile of Sr, K, Mo and nitric acid in various stages and their distribution in process stream solutions are presented

  14. Synthesis, characterization and antibacterial activity of new complexes of some lanthanide ions with 15-crown-5 and 18-crown-6

    Directory of Open Access Journals (Sweden)

    Hussein Al-Amery

    2016-05-01

    Full Text Available Complexes of some lanthanide picrates (Ln3+ = Pr3+, Nd3+ and Dy3+ with 15-crown-5 and 18-crown-6 were synthesized and characterized by elemental analysis, ICP-AES, FTIR, 1H-NMR, 13C-NMR and UV-Visible spectrophotometric methods, thermal analysis (TGA & DTG, magnetic susceptibility , molar conductance and melting points. Also an in-vitro study on pathogenic gram positive (Staphylococcus aureus and pathogenic gram negative bacteria (Escherichia coli, Salmonella and pseudomonas aeruginosa was performed and the results were compared to those of a broad spectrum antibiotic (Chloramphinicol. The complexes of 15-crown-5 have the general formula [Ln(15C52(Pic]Pic2.nH2O where (Ln3+ = Nd3+ and Dy3+, (Pic = Picrate anion and (n = 2 or 4 except for Pr3+ complex which has the formula [Pr(15C5]Pic3.H2O , the 18-crown-6 complexes have the general formula [Ln(18C6]Pic3 where (Ln3+ = Pr3+ and Nd3+ except for Dy3+ complex which has the formula [Dy(18C6(Pic]Pic2.3H2O. In 15-crown-5 complexes both Nd3+ and Dy3+ were coordinated with two 15-crown-5 ligands and one picrate anion through its phenolic oxygen and the oxygen of it’s ortho nitro group, except for Pr3+ which was coordinated with only one 15-crown-5 ligand leaving three picrate anions as counter ions. In 18-crown-6 complexes both Pr3+ and Nd3+ were coordinated with one 18-crown-6 ligand leaving all the three picrate anions as counter ions outside the coordination sphere, except for the Dy3+ complex which was coordinated with one 18-crown-6 ligand and one picrate anion.

  15. Comparison of effect of desensitizing agents on the retention of crowns cemented with luting agents: an in vitro study

    OpenAIRE

    Jalandar, Sonune Shital; Pandharinath, Dange Shankar; Arun, Khalikar; Smita, Vaidya

    2012-01-01

    PURPOSE Many dentists use desensitizing agents to prevent hypersensitivity. This study compared and evaluated the effect of two desensitizing agents on the retention of cast crowns when cemented with various luting agents. MATERIALS AND METHODS Ninety freshly extracted human molars were prepared with flat occlusal surface, 6 degree taper and approximately 4 mm axial length. The prepared specimens were divided into 3 groups and each group is further divided into 3 subgroups. Desensitizing agen...

  16. Triaquachlorido(18-crown-6barium chloride

    Directory of Open Access Journals (Sweden)

    Min-Min Zhao

    2012-03-01

    Full Text Available In the title compound, [BaCl(C12H24O6(H2O3]Cl, the BaII atom, the coordinating and free Cl− anions, one coordinating water molecule and two O atoms of an 18-crown-6 molecule lie on a mirror plane. The environment of the ten-coordinate Ba2+ ion is defined by one Cl atom, three water molecules and six O atoms from the macrocyclic ether. The macrocycle adopts a conformation with an approximate D3d symmetry. In the crystal, O—H...Cl hydrogen bonds link the complex cations and Cl− anions into a two-dimensional network parallel to (010. An intramolecular O—H...Cl hydrogen bond is also present.

  17. Silica crown refractory corrosion in glass melting furnaces

    Directory of Open Access Journals (Sweden)

    Balandis A.

    2011-01-01

    Full Text Available The critical parameters of silica refractories, such as compressive strength, bulk, density, quantity of silica, microstructure and porosity were evaluated of unused and used bricks to line the crowns of glass furnaces, when the rate of corrosion of crowns were about 2 times greater. The change of these parameters, the chemical composition and formation of the microcracks in the used silica refractories material were studied. It was established that the short time at service of container glass furnace crown can be related to low quality of silica brick: high quantity of CaO and impurities, low quantity of silica, low quantity of silica, transferred to tridymite and cristobalite and formation of 5-10 μm and more than 100 μm cracks in the crown material. The main reason of corrosion high quality silica bricks used to line the crown of electrovacuum glass furnace is the multiple cyclic change of crown temperature at 1405 - 1430°C range in the initial zone of crown and at 1575 - 1605°C range in the zone of highest temperatures.

  18. Review of Alberta Crown Crude Oil Marketing Program

    International Nuclear Information System (INIS)

    This report contains an independent evaluation of the operations of the private marketing agents that are currently marketing the Alberta Crown's share of royalty crude oil. The evaluation includes a review of pricing performance, working relationship, current issues and the overall performance of the marketing arrangements during the fiscal years of 1997 and 1998. Overall, the outsourcing of sales of Crown production to agents is judged to be successful. For example, it has been noted that agents are becoming more aggressive in maintaining and increasing their margins. On the other hand, the increased level of aggressiveness in marketing, while tending to maximize Crown revenues, is also creating a potential conflict on how margins should be shared between the Crown and its agents. Also, there has been evidence of some management issues between the agents and the Crown concerning the extent to which the Crown should share in any increased value which the agent generates by increased third party marketing activities. These differences need to be addressed in order to maintain the strong performance of the marketing program. The consultants also recommend additional guidelines on risk management issues that more clearly define the Crown's risk tolerance. 2 tabs., 4 figs

  19. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns

    Directory of Open Access Journals (Sweden)

    Jae-Hong Kim

    2016-01-01

    Full Text Available The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice—before and after crystallization—using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α=0.05. Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P<0.05. None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold.

  20. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns.

    Science.gov (United States)

    Kim, Jae-Hong; Oh, Seunghan; Uhm, Soo-Hyuk

    2016-01-01

    The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM) system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice-before and after crystallization-using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α = 0.05). Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P < 0.05). None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold. PMID:27123453

  1. The sensitivity of length of pregnancy using clinical estimate of gestation versus last menstrual period: an example with particulate matter and preterm birth

    Science.gov (United States)

    Estimating gestational age is usually based on last menstrual period date (LMP) or clinical estimation (CGA); both approaches introduce error and potential bias. Differences in the two methods of gestational age assignment may lead to misclassification and differences in risk est...

  2. Challenges in reconstructing an isolated anterior tooth with a metal-free crown

    Directory of Open Access Journals (Sweden)

    Max Doria Costa

    2013-01-01

    Full Text Available Introduction: Currently, new esthetic treatments are available to the dentist due to the advent of ceramic-ceramic prostheses. A new option has become part of daily clinical practice, with the promise of esthetic optimization through the elimination of metal in prosthetic crowns. The translucence of these new systems allows the transmission of light through the tooth structure, minimizing gingival darkness and producing a vibrant and natural appearance. Case Report: The patient, 30 years old, female, showed with a fractured tooth crown at the cervical level in the right lateral incisive. It was observed that the tooth had prior adequate endodontic treatment. A metal-free restorative system was selected. A plaster model was obtained for subsequent tooth preparative scanning and manufacture of ceramic framework. After receiving the framework, adjustments were made and the color choice of covering ceramic, following the protocol of choice for a chroma suboptimal aiming further characterization. After the ceramics application, adjustments in shape, texture, and occlusion were made. The crown was characterized by exterior paint, getting a favorable result, restoring esthetics and function. Discussion : The metal-free systems are a viable alternative to the restorative treatment when esthetics is desired, allowing a natural and harmonious smile, combined with the reliability of the restorative material.

  3. Crown lengthening procedure following intentional endodontic therapy for correction of supra-erupted posterior teeth: Case series with long-term follow-up

    Science.gov (United States)

    Patil, Shruti Arun; Kulkarni, Sudhindra; Thakur, Srinath; Naik, Balaram

    2016-01-01

    Context: The crown lengthening procedure (CLP) is routinely carried out to correct gingival levels and achieve esthetic contours and adequate crown lengths for restorative purposes. Though the short-term outcomes have been found to be stable, long-term results are not much reported. Aims: To evaluate the long-term stability of the marginal bone levels, gingival levels, and the status of the teeth, which underwent endodontic therapy, followed by CLP and final restorations. Settings and Design: Institutional setting, long-term case series. Materials and Methods: Case records of the patients who underwent CLP and endodontic therapy for corrections of the supra-erupted teeth to regain the lost interocclusal spaces were retrieved, and the cases with complete set of the clinical and radiographs were taken. All the cases were recalled and bone levels on the radiographs, bleeding on probing, probing pocket depths, and changes in the soft tissue margins were evaluated. Statistical Analysis Used: Descriptive analysis. Results: A total of 25 teeth had undergone CLP and endodontic therapy and final restorations for a minimum of 24 months. The mean post-restorative duration was 50.8 ± 22.48 months (range 24–96 months). All the teeth were functional and asymptomatic with 100% survival. Interdental bone loss of 1 mm, probing pockets of 5 mm, and 1 mm buccal recession were observed in 16% of the sites. The amount of interocclusal space regained was adequate to restore the missing teeth in the opposing arch. Conclusions: The CLP is a predictive procedure for correction of supra-erupted teeth. The survival of the teeth that underwent the procedure in the present study was 100% over 24–96 months. PMID:27041850

  4. Estimation of genome length

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The genome length is a fundamental feature of a species. This note outlined the general concept and estimation method of the physical and genetic length. Some formulae for estimating the genetic length were derived in detail. As examples, the genome genetic length of Pinus pinaster Ait. and the genetic length of chromosome Ⅵ of Oryza sativa L. were estimated from partial linkage data.

  5. Fractal approach to computer-analytical modelling of tree crown

    International Nuclear Information System (INIS)

    In this paper we discuss three approaches to the modeling of a tree crown development. These approaches are experimental (i.e. regressive), theoretical (i.e. analytical) and simulation (i.e. computer) modeling. The common assumption of these is that a tree can be regarded as one of the fractal objects which is the collection of semi-similar objects and combines the properties of two- and three-dimensional bodies. We show that a fractal measure of crown can be used as the link between the mathematical models of crown growth and light propagation through canopy. The computer approach gives the possibility to visualize a crown development and to calibrate the model on experimental data. In the paper different stages of the above-mentioned approaches are described. The experimental data for spruce, the description of computer system for modeling and the variant of computer model are presented. (author). 9 refs, 4 figs

  6. Acetylene–ammonia–18-crown-6 (1/2/1

    Directory of Open Access Journals (Sweden)

    Tobias Grassl

    2012-10-01

    Full Text Available The title compound, C2H2·C12H24O6·2NH3, was formed by co-crystallization of 18-crown-6 and acetylene in liquid ammonia. The 18-crown-6 molecule has threefold rotoinversion symmetry. The acteylene molecule lies on the threefold axis and the whole molecule is generated by an inversion center. The two ammonia molecules are also located on the threefold axis and are related by inversion symmetry. In the crystal, the ammonia molecules are located below and above the crown ether plane and are connected by intermolecular N—H...O hydrogen bonds. The acetylene molecules are additionally linked by weak C—H...N interactions into chains that propagate in the direction of the crystallographic c axis. The 18-crown-6 molecule [occupancy ratio 0.830 (4:0.170 (4] is disordered and was refined using a split model.

  7. Influence of porcelain veneering on the marginal fit of Digident and Lava CAD/CAM zirconia ceramic crowns

    Science.gov (United States)

    Pak, Hyun-Soon; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun

    2010-01-01

    PURPOSE Marginal fit is a very important factor considering the restoration's long-term success. However, adding porcelain to copings can cause distortion and lead to an inadequate fit which exposes more luting material to the oral environment and causes secondary caries. The purpose of this study was to compare the marginal fit of 2 different all-ceramic crown systems before and after porcelain veneering. This study was also intended to verify the marginal fit of crowns originated from green machining of partially sintered blocks of zirconia (Lava CAD/CAM system) and that of crowns obtained through machining of fully sintered blocks of zirconia (Digident CAD/CAM system). MATERIALS AND METHODS 20 crowns were made per each system and the marginal fit was evaluated through a light microscope with image processing (Accura 2000) at 50 points that were randomly selected. Each crown was measured twice: the first measurement was done after obtaining a 0.5 mm coping and the second measurement was done after porcelain veneering. The means and standard deviations were calculated and statistical inferences among the 2 groups were made using independent t-test and within the same group through paired t-test. RESULTS The means and standard deviations of the marginal fit were 61.52 ± 2.88 µm for the Digident CAD/CAM zirconia ceramic crowns before porcelain veneering and 83.15 ± 3.51 µm after porcelain veneering. Lava CAD/CAM zirconia ceramic crowns showed means and standard deviations of 62.22 ± 1.78 µm before porcelain veneering and 82.03 ± 1.85 µm after porcelain veneering. Both groups showed significant differences when analyzing the marginal gaps before and after porcelain veneering within each group. However, no significant differences were found when comparing the marginal gaps of each group before porcelain veneering and after porcelain veneering as well. CONCLUSION The 2 all-ceramic crown systems showed marginal gaps that were within a reported clinically

  8. Photodissociation of Non-Covalent Peptide-Crown Ether Complexes

    OpenAIRE

    Wilson, Jeffrey J.; Kirkovits, Gregory J.; Sessler, Jonathan L.; Brodbelt, Jennifer S.

    2007-01-01

    Highly chromogenic 18-crown-6-dipyrrolylquinoxaline coordinates primary amines of peptides, forming non-covalent complexes that can be transferred to the gas phase by electrospray ionization. The appended chromogenic crown ether facilitates efficient energy transfer to the peptide upon ultraviolet irradiation in the gas phase, resulting in diagnostic peptide fragmentation. Collisional activated dissociation (CAD) and infrared multiphoton dissociation (IRMPD) of these non-covalent complexes re...

  9. An interdisciplinary approach to treat crown-root-fractured tooth

    OpenAIRE

    Ying Chun Sun; Ying Li; Jian Tong; Ping Gao

    2013-01-01

    Restoration of a crown-root subgingival fractured tooth, especially at anterior aesthetic zones is still a great challenge for restorative dentists. Crown lengthening procedure alone has the disadvantage of high gingival curve of the final restoration, which was not discontinuous to adjacent teeth and thus compromise cosmetic outcomes. The objective of this report is to display a new interdisciplinary approach which combining endodontic root canal treatment, orthodontic extrusion, periodontal...

  10. Immediate esthetic crown with a facet of the extracted element

    OpenAIRE

    Di Giacomo, Giovanni de Almeida Prado; Magalhães, Amanda; Ajzen, Sergio

    2014-01-01

    The present report describes a case of implant loading with an immediate temporary crown. The buccal crown surface was removed from the extracted tooth to obtain an aesthetically satisfactory result. After periodontal treatment, tooth 21 appeared proclined and showed Grade 3 mobility, indicating the need for its extraction. The remaining bone was imaged using computed tomography, and virtual surgical planning was performed using these results. The implant was immediately loaded postextraction...

  11. Point processes in forestry : an application to tree crown detection

    OpenAIRE

    Perrin, Guillaume; Descombes, Xavier; Zerubia, Josiane

    2006-01-01

    In this research report, we aim at extracting tree crowns from remotely sensed images using marked point processes of discs and ellipses. Our approach is indeed to consider that the data are some realizations of a marked point process. Once a geometrical object is defined, we sample a marked point process defined by a density with a Reversible Jump Markov Chain Monte Carlo dynamics and simulated annealing to get the maximum a posteriori estimator of the tree crown distribution on the image. I...

  12. The Convergence Angle of Full-coverage Crown Preparations Made by Dental Students

    Directory of Open Access Journals (Sweden)

    R. Baghai Naini

    2008-03-01

    Full Text Available Objective: A clinically feasible convergence angle in full-coverage crown preparations, meeting the requirements for proper retention and resistance forms, has always been a matter of interest for laboratory and clinical researches. This study aims to evaluate the angle in teeth prepared by both under- and post-graduate students at Tehran University of Medical Sciences, Faculty of dentistry, Department of Prosthodontics.Materials and Methods: Samples consisted of 196 prepared teeth for full-coverage crown restoration by third year postgraduate and fifth year undergraduate students in the Department of Prosthodontics. Two images were obtained from each die by a scanner and both bucco-lingual and mesio-distal convergence angles were measured, by two different assessors, via Auto CAD 14 software. The data were analyzed using analysis of variance.Results: There were statistically significant differences between the teeth prepared by un-der- and post-graduate students in mesio-distal convergence angles of all maxillary teeth, except for canines. Significant differences were found between bucco-lingual convergence angles of the maxillary canines and molars.Conclusion: The recently recommended convergence angles are more clinically feasible compared to the classic 4 to 10 degrees that was previously suggested for all teeth. It also seems that clinical experience does not necessarily lead to a decrease in convergence an-gles during preparation.

  13. Amplified fragment length polymorphism of clinical and environmental Vibrio cholerae from a freshwater environment in a cholera-endemic area, India

    Directory of Open Access Journals (Sweden)

    Sharma Naresh C

    2011-09-01

    Full Text Available Abstract Background The region around Chandigarh in India has witnessed a resurgence of cholera. However, isolation of V. cholerae O1 from the environment is infrequent. Therefore, to study whether environmental nonO1-nonO139 isolates, which are native to the aquatic ecosystem, act as precursors for pathogenic O1 strains, their virulence potential and evolutionary relatedness was checked. Methods V. cholerae was isolated from clinical cases of cholera and from water and plankton samples collected from freshwater bodies and cholera-affected areas. PCR analysis for the ctxA, ctxB, tcpA, toxT and toxR genes and AFLP with six primer combinations was performed on 52 isolates (13 clinical, 34 environmental and 5 reference strains. Results All clinical and 3 environmental isolates belonged to serogroup O1 and remaining 31 environmental V. cholerae were nonO1-nonO139. Serogroup O1 isolates were ctxA, tcpA (ElTor, ctxB (Classical, toxR and toxT positive. NonO1-nonO139 isolates possessed toxR, but lacked ctxA and ctxB; only one isolate was positive for toxT and tcpA. Using AFLP, 2.08% of the V. cholerae genome was interrogated. Dendrogram analysis showed one large heterogeneous clade (n = 41, with two compact and distinct subclades (1a and 1b, and six small mono-phyletic groups. Although V. cholerae O1 isolates formed a distinct compact subclade, they were not clonal. A clinical O1 strain clustered with the nonO1-nonO139 isolates; one strain exhibited 70% similarity to the Classical control strain, and all O1 strains possessed an ElTor variant-specific fragment identified with primer ECMT. Few nonO1-nonO139 isolates from widely separated geographical locations intermingled together. Three environmental O1 isolates exhibited similar profiles to clinical O1 isolates. Conclusion In a unique study from freshwater environs of a cholera-endemic area in India over a narrow time frame, environmental V. cholerae population was found to be highly heterogeneous

  14. INTEGRATION OF FLUORESCENCE DIFFERENTIAL PATH-LENGTH SPECTROSCOPY TO PHOTODYNAMIC THERAPY OF THE HEAD AND NECK TUMORS IS USEFUL IN MONITORING CLINICAL OUTCOME

    Directory of Open Access Journals (Sweden)

    Baris eKarakullukcu

    2015-04-01

    Full Text Available The use of fluorescence differential pathlength spectroscopy (FDPS has the potential to provide real-time information on photosensitiser pharmacokinetics, vascular physiology and photosensitizer photobleaching based dosimetry of tumors in the oral cavity receiving m-tetrahydroxyphenylchlorin (mTHPC photodynamic therapy (PDT. Reflectance spectra can be used provide quantitative values of oxygen saturation, blood volume fraction, blood vessel diameter, and to determine the local optical properties that can be used to correct raw fluorescence for tissue absorption. Patients and methods: Twenty-seven lesions in the oral cavity, either dysplasias or cancer were interrogated using FDPS, before and immediately after the therapeutic illumination. The average tumor center to normal mucosa ratio of fluorescence was 1.50 ± 0.66. mTHPC photobleaching was observed in 24 of the lesions treated. The average extent of photobleaching was 81% ± 17%. Information from FDPS spectroscopy coupled with the clinical results of the treatment identified 3 types of correctable errors in the application of mTHPC-PDT: Two patients exhibited very low concentrations of photosensitizer in tumour center, indicating an ineffective i.v. injection of photosensitiser or an erroneous systemic distribution of mTHPC. In one in tumor we observed no photobleaching accompanied by a high blood volume fraction in the illuminated tissue, suggesting that the presence of blood prevented therapeutic light reaching the target tissue. All 3 of the these lesions had no clinical response to PDT. In four patients we observed less than 50% photobleaching at the tumor margins , suggesting a possible geographic miss. One patient in this group had a recurrence within 2 months after PDT even though the initial response was good. The integration of FDPS to clinical PDT yields data on tissue physiology, photosensitiser content and photobleaching that can help identify treatment errors that can

  15. Stress distribution in implant-supported prostheses using different connection systems and cantilever lengths: digital photoelasticity.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Shibayama, Ricardo; Gennari Filho, Humberto; de Medeiros, Rodrigo Antonio; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline; de Araújo, Cleudmar Amaral

    2016-01-01

    Photoelastic analysis was used to evaluate the biomechanical behaviour of implant-supported, double-screwed crowns with different connection systems and cantilever lengths. Three models were made in PL-2 photoelastic resin and divided into six groups, on the basis of the implant connection system (external hexagon [EH] or Morse taper [MT]), type of abutment (Mini Pilar [Neodent, Curitiba, Paraná, Brazil] or "UCLA") and number of crowns in the cantilever (one or two). The implant-prosthesis unit was placed in a circular polariscope. Occlusal surfaces of the crowns were subjected to 100-N loads in the axial and oblique (45°) directions in a universal testing machine (EMIC). Generated stresses were recorded and analysed qualitatively in a graphics program (Adobe Photoshop). Under axial loading, all of the groups had similar numbers of fringes, which were increased when the crowns were subjected to oblique loading. The highest number of fringes was found during oblique loading in the EH + Mini Pilar group. In conclusion, although the type of implant connection system did not have a direct influence on the stress distribution for axial loading, the cantilever length did have a direct influence on stress distribution. Models with two crowns in the cantilever showed more stress, with a greater concentration of force on the cervical part of the implant. PMID:26783652

  16. Microbiological and microscopic analysis of the pulp of non-vital traumatized teeth with intact crowns

    Directory of Open Access Journals (Sweden)

    Kely Firmino Bruno

    2009-10-01

    Full Text Available OBJECTIVE: This study evaluated the presence of microorganisms and analyzed microscopically the pulp of 20 traumatized human teeth with intact crowns and clinical diagnosis of pulp necrosis, based on the association of at least three of the clinical criteria: crown discoloration, negative response to thermal and electric pulp vitality tests, positive response to vertical and horizontal percussion, pain on palpation or mobility. MATERIAL AND METHODS: Microbiological collection was performed from the root canals to evaluate the presence of microorganisms. The pulp samples were stained with hematoxylin and eosin (H.E. for histological evaluation of possible morphological alterations. RESULTS: Analysis of results was performed by statistical tests (linear regression test and diagnostic analysis and subjective analysis of the sections stained with H.E. and revealed that only 15% of the sample did not exhibit microbial development. The time elapsed between dental trauma and onset of endodontic intervention ranged from 15 days to 31 months; the percussion test presented high sensitivity (80% for detection of microorganisms in the root canal of traumatized teeth; 3 teeth (15% did not present pulp tissue, being characterized as complete autolysis; analysis of pulp samples was performed on the other 17 cases, among which 3 (15% exhibited partial necrosis without possibility of repair and 14 presented complete necrosis; none of the clinical criteria employed for the diagnosis of pulp necrosis in traumatized teeth was pathognomonic. CONCLUSIONS: The present results allowed the following conclusions: with regard to microbiological findings, 85% of teeth presented microorganisms in the root canal, despite the presence of an intact crown. Concerning the microscopic findings, 100% of traumatized teeth presented pulp necrosis; the pulp vitality tests based on pulp response to heat, cold and vertical percussion were the most reliable to diagnose pulp necrosis in

  17. Comparative photophysical behaviour of naphthalene-linked crown ethers and aza crown ethers of varying cavity dimensions

    Indian Academy of Sciences (India)

    Subhodip Samanta; Pinki Saha Sardar; Shyam Sundar Maity; Anirban Pal; Maitrayee Basu Roy; Sanjib Ghosh

    2007-03-01

    A comparative time-resolved emission studies of several naphtho-crown ethers I-V, where metal ions can be complexed in a predetermined orientation with respect to the naphthalene (Naph) - plane and naphthalene-linked aza crown ethers (L1 and L2) have been presented. In both the systems, crown ethers and aza crown ethers, naphthalene fluorescence gets quenched. In the systems I to V, the quenching is mainly due to efficient spin-orbit coupling (SOC) leading to greater population of the lowest triplet state of naphthalene. This SOC depends on the orientation of the crown ring with respect to the Naph--plane. However, in the systems L1 and L2, the quenching is due to photoinduced electron transfer (PET) from nitrogen lone pair of the aza crown ring to naphthalene moiety and consequent exciplex formation. The results have been interpreted using the time-resolved emission studies of all the compounds in various solvents, their alkali metal ion complexes, and protonated ligands.

  18. Clinical significance of telomerase and its associate genes expression in the maintenance of telomere length in squamous cell carcinoma of the esophagus

    Institute of Scientific and Technical Information of China (English)

    Chung-Ping Hsu; Li-Wen Lee; Sen-Ei Shai; Chih-Yi Chen

    2005-01-01

    AIM: To observe the interaction between the expression of telomerase activity (TA) and its associate genes in regulation of the terminal restriction fragment length(TRFL) in esophageal squamous cell carcinoma (SCC).METHODS: Seventy-four specimens of esophageal SCC were examined. The TA was measured by telomeric repeat amplification protocol (TRAP) assay, and the associated genes [human telomerase-specific reverse transcriptase (hTERT), hTERC, TP1, c-Myc, TRF1,and TRF2] were detected using RT-PCR method. The TRFL was measured by Telomere Length Assay Kit and Southern blotting. The correlations between the expression of telomerase and its associated genes with the TRFL and survivals were examined.RESULTS: Expressions of the TA, hTERT, hTERC, TP1,c-Myc, TRF1, and TRF2 genes were observed in 85.1%,64.9%, 79.7%, 100.0%, 94.6%, 82.4%, and 91.9% of the tumor tissues, respectively. The TRFL of the tumor and normal esophageal tissues were 2.70±1.42 and 4.93±1.74 kb, respectively (P<0.0001). The TRFL of the telomerase positive and telomerase negative tumor tissues were 2.72±1.44 and 2.58±1.32 kb, respectively (P = 0.767).The TRFL ratios (TRFLR) of the telomerase positive and telomerase negative tumor tissues were 0.55±0.22 and 0.59±0.41, respectively (P = 0.742). The expression rates of h-TERT (P = 0.0002), hTERC (P<0.0001), and TRF1(P = 0.002) in the tumor tissues are higher than those of the normal paired tissues. Though TA is markedly activated in tumor tissues (P<0.0001), its expression is not related to clinicopathological parameters including gender, tumor differentiation, and TNM stages. The cumulative 4-year survival rates of telomerase positive and telomerase negative cases were 35.86% and 31.2%,respectively (P = 0.8442). The cumulative 4-year survival rates of patients with their TRFLR ≤85% and >85%were 38.7% and 15.7%, respectively (P = 0.1307).CONCLUSION: Though telomerase expression is not related to tumor stages and prognosis, our data support

  19. Predicting tree crown defoliation using color-infrared orthophoto maps

    Directory of Open Access Journals (Sweden)

    Eigirdas M

    2013-01-01

    Full Text Available Orthophoto maps based on color-infrared aerial photography have been used by the Lithuanian forest inventory since 2001. This study aimed to investigate the opportunities for using these orthophoto maps to predict tree crown defoliation at the single tree and sample plot levels. The test area was located in the Aukstaitija National Park, eastern Lithuania, and it was photographed in the summer of 2008 using a Vexcel UltraCam D digital frame aerial camera to produce digital orthophoto maps with a 0.5 x 0.5 m ground sampling density. Some 1721 tree crowns (mainly pine, spruce and birch, located in 166 permanent sample plots, were identified and delineated on the orthophoto maps. Crown defoliation and other dendrometric characteristics were field-estimated for all of these trees in summer 2008. Judgments on the suitability of using color-infrared aerial photography based orthophotos to estimate tree crown defoliation were based on the accuracy of the defoliation prediction. Defoliation for each crown was predicted using the non-parametric k-Nearest Neighbor (k-NN method and characteristics extracted from the digital orthophoto maps as the auxiliary variables for prediction. Prediction accuracies were validated using the “Leave One Out” technique by comparing the predicted data with data from field-assessed crown defoliations. The lowest root mean square errors for the predicted tree crown defoliation values were 7.564 for pine trees, 9.166 for spruce and 7.712 for birch and the highest coefficients of correlation between field-estimated and predicted crown defoliations were 0.576, 0.600 and 0.386, respectively. However, there was no best performing solution for using the k-NN prediction found, as the best results were achieved using different approaches. Next, predicted and field estimated tree crown defoliation values were aggregated up to the sample plot level by taking an averaging of trees in the same sample plot. The root mean square error

  20. A prospective study of leukocyte telomere length and risk of phobic anxiety among women.

    Science.gov (United States)

    Ramin, Cody; Wang, Wei; Prescott, Jennifer; Rosner, Bernard; Simon, Naomi M; De Vivo, Immaculata; Okereke, Olivia I

    2015-12-15

    We prospectively examined the relation of relative telomere lengths (RTLs), a marker of biological aging, to phobic anxiety in later-life. RTLs in peripheral blood leukocytes were measured among 3194 women in the Nurses' Health Study who provided blood samples in 1989/90. The Crown-Crisp Phobic Index (CCI, range=0–16) was assessed in 1988 and 2004. Only participants with CCI≤3 (consistent with no meaningful anxiety symptoms) in 1988 were included. We related baseline RTLs to odds ratios (ORs) of incident high phobic anxiety symptoms (CCI≥6). To enhance clinical relevance, we used finite mixture modeling (FMM) to relate baseline RTLs to latent classes of CCI in 2004. RTLs were not significantly associated with high phobic anxiety symptoms after 16 years of follow-up. However, FMM identified 3 groups of phobic symptoms in later-life: severe, minimal/intermediate, and non-anxious. The severe group had non-significantly shorter multivariable-adjusted mean RTLs than the minimal/intermediate and non-anxious groups. Women with shorter telomeres vs. longest telomeres had non-significantly higher likelihood of being in the severe vs. non-anxious group. Overall, there was no significant association between RTLs and incident phobic anxiety symptoms. Further work is required to explore potential connections of telomere length and emergence of severe phobic anxiety symptoms during later-life. PMID:26603336

  1. Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

    Science.gov (United States)

    Zheng, Yihao; Belmont, Barry; Shih, Albert J

    2016-07-01

    Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. PMID:27160429

  2. Biology and control of the raspberry crown borer (Lepidoptera: Sesiidae).

    Science.gov (United States)

    McKern, Jacquelyn A; Johnson, Donn T; Lewis, Barbara A

    2007-04-01

    This study explored the biology of raspberry crown borer, Pennisetia marginata (Harris) (Lepidoptera: Sesiidae), in Arkansas and the optimum timing for insecticide and nematode applications. The duration of P. marginata's life cycle was observed to be 1 yr in Arkansas. Insecticide trials revealed that bifenthrin, chlorpyrifos, imidacloprid, metaflumizone, and metofluthrin efficacy were comparable with that of azinphosmethyl, the only labeled insecticide for P. marginata in brambles until 2005. Applications on 23 October 2003 for plots treated with bifenthrin, chlorpyrifos, and azinphosmethyl resulted in >88% reduction in larvae per crown. Applications on 3 November 2004 of metaflumizone, metofluthrin, and bifenthrin resulted in >89% reduction in larvae per crown. Applications on 7 April 2005 for metofluthrin, imidacloprid, bifenthrin, metaflumizone, and benzoylphenyl urea resulted in >64% reduction in the number of larvae per crown. Applications on 6 May 2004 did not reduce larval numbers. The optimum timing for treatments was found to be between October and early April, before the larvae tunneled into the crowns of plants. Applying bifenthrin with as little as 468 liters water/ha (50 gal/acre) was found to be as effective against larvae as higher volumes of spray. Nematode applications were less successful than insecticides. Nematode applications of Steinernemafeltiae, Steinernema carpocapsae, and Heterorhabditis bacteriophora reduced larvae counts per plant by 46, 53, and 33%, respectively. PMID:17461064

  3. Crown-formation time of a fossil hominid premolar tooth.

    Science.gov (United States)

    Beynon, A D; Dean, M C

    1987-01-01

    Studies using surface or internal enamel growth indicators in hominids have suggested that crown-formation times were shorter than those in modern man. The crown-formation time in a robust australopithecine premolar tooth was calculated by counting enamel cross-striations, which correspond to daily increments of formation, on a replica of the fractured internal enamel surface of cuspal enamel using scanning electron microscopy. Cervical enamel completion time was estimated using other growth indicators including striae, and using measured and calculated cross-striation repeat intervals, giving a completion time of approx. 2.4 yr. This is much shorter than reported premolar crown formation times in modern man. These findings support the concept of an abbreviated period of dental development, with implications on the duration of the growth period in early hominids. PMID:3130039

  4. An interdisciplinary approach to reconstruct a fractured tooth under an intact all ceramic crown: Case report with four years follow up

    Directory of Open Access Journals (Sweden)

    Sudhir Bhandari

    2011-01-01

    Full Text Available Trauma causing the fracture of a restored tooth with the extracoronal full coverage prosthesis remaining intact is a common occurrence in dental practice. Reconstruction of the damaged tooth foundation and recementation of the crown can pose quite a challenge for the restorative dentist. This case report describes an innovative interdisciplinary chairside technique for the recementation of an all-ceramic crown on a fractured maxillary central incisor. The course of care described is effective, affordable, and saves time in comparison with other treatment options for such clinical situations.

  5. Synthesis and adsorption properties of chitosan-crown ether resins

    Institute of Scientific and Technical Information of China (English)

    彭长宏; 陈艺锋; 唐谟堂

    2003-01-01

    Two kinds of novel chitosan-crown ether resins, Schiff base type chitosan-benzo-15-crown-5 (CTS-B15)and chitosan-benzo-18-crown-6 (CTS-B18), were synthesized through the reaction between -NH2 in chitosan and -CHO in 4′-formyl benzo-crown ethers. Their structures were characterized by elemental analysis and FT-IR spectra analysis. The elemental analysis results show that the mass fractions of nitrogen in CTS-B15 and CTS-B18 are much lower than those of chitosan. The results of FT-IR spectra of CTS-B15 and CTS-B18 reveal that there exist characteristic peak of C= N, N-H and Ar, and characteristic peak of pyr anoside in the chain of chitosan-crown ether resins, showing that the structures of chitosan-crown ethers are as expected. The adsorption properties of CTS-B15 and CTS-B18 for Pd2+ , Cu2 + and Hg2+ were studied and the experimental results show that these adsorbents have both good adsorption characterization and especially high particular adsorption selectivity for Pd2+ when Cu2+ and Hg2+ are in coexistence, and the coefficients of selectivity of CTS-B15 and CTS-B18 for metal ions are KPd2+/cu2+ =7.56, KPd2+/Hg2+ = 68.00, Kcu2+/Hg2+ = 9.00 and KPd2+/cu2+ = 6.00, KPd2+/Hg2+ = 19. 00, Kcu2+/Hg2+ = 3.00, respectively.

  6. Museum security and the Thomas Crown Affair.

    Energy Technology Data Exchange (ETDEWEB)

    Michaud, E. C. (Nuclear Engineering Division)

    2010-01-01

    Over the years, I've daydreamed about stealing a Vermeer, a Picasso, or Rembrandt. It tickles me, as much as watching the reboot of The Thomas Crown Affair. Why is it, do you suppose, so much fun to think about stealing a world renowned piece off the wall of a major metropolitan museum? Is it the romantic thoughts of getting away with it, walking past infrared detectors, and pressure sensors ala Indiana Jones with the sack of sand to remove the idol without triggering the security system? Is it the idea of snatching items with such fantastic prices, where the romance of possessing an item of such value is less intoxicating than selling it to a private collector for it to never be seen again? I suspect others share my daydreams as they watch theater or hear of a brazen daylight heist at museums around the world, or from private collections. Though when reality sets in, the mind of the security professional kicks in. How could one do it, why would one do it, what should you do once it's done? The main issue a thief confronts when acquiring unique goods is how to process or fence them. They become very difficult to sell because they are one-of-a-kind, easy to identify, and could lead to the people involved with the theft. The whole issue of museum security takes up an ironic twist when one considers the secretive British street artist 'Banksy'. Banksy has made a name for himself by brazenly putting up interesting pieces of art in broad daylight (though many critics don't consider his work to be art) on building walls, rooftops, or even museums. I bring him up for a interesting take on what may become a trend in museum security. In March of 2005, Banksy snuck a piece of his called 'Vandalized Oil Painting' into the Brooklyn Museum's Great Historical Painting Wing, plus 3 other pieces into major museums in New York. Within several days, 2 paintings had been torn down, but 2 stayed up much longer. In his home country of the UK, a

  7. CROWN: A service grid middleware with trust management mechanism

    Institute of Scientific and Technical Information of China (English)

    HUAI Jinpeng; HU Chunming; LI Jianxin; SUN Hailong; WO Tianyu

    2006-01-01

    Based on a proposed Web service-based grid architecture, a service grid middleware system called CROWN is designed in this paper. As the two kernel points of the middleware, the overlay-based distributed grid resource management mechanism is proposed, and the policy-based distributed access control mechanism with the capability of automatic negotiation of the access control policy and trust management and negotiation is also discussed in this paper. Experience of CROWN testbed deployment and application development shows that the middleware can support the typical scenarios such as computing-intensive applications, data-intensive applications and mass information processing applications.

  8. Synthesis of Schiff Base Calix[4]arene Crowns

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This letter reports the synthesis of Schiff base calix[4]arene crowns containing m-xylylene phenol subunit, in which calix[4]arene Schiff base crowns 2a, 2b and 2c were formed by 1:1 condensation of calix[4]arene diamine 1 with dialdehydes (2, 6-diformyl-4-chlorophenol 3a, 2, 6-diformyl-4-methylphenol 3b, 2, 6-diformyl-4-tert-butylphenol 3c) under high dilute condition in refluxing anhydrous ethanol in 65-70% yield.

  9. Immediate esthetic crown with a facet of the extracted element

    Science.gov (United States)

    Di Giacomo, Giovanni de Almeida Prado; Magalhães, Amanda; Ajzen, Sergio

    2014-01-01

    The present report describes a case of implant loading with an immediate temporary crown. The buccal crown surface was removed from the extracted tooth to obtain an aesthetically satisfactory result. After periodontal treatment, tooth 21 appeared proclined and showed Grade 3 mobility, indicating the need for its extraction. The remaining bone was imaged using computed tomography, and virtual surgical planning was performed using these results. The implant was immediately loaded postextraction into the fresh alveolus without a graft and flap procedure. The temporary tooth, which was manufactured using the extracted buccal surface, was a simple, fast, and low cost procedure that produced an excellent esthetic outcome. PMID:25202225

  10. Evaluation of the onset of failure under mechanical and thermal stresses on luting agent for metal-ceramic and metal crowns by finite element analysis

    Directory of Open Access Journals (Sweden)

    Hema Agnihotri

    2010-01-01

    Full Text Available Long-term clinical failures of cemented prosthesis depend, to a large extent, on the integrity of the luting agent. The causative factors that lead to microfracture and, hence, failure of the luting agents are the stresses acting inside the oral cavity. Therefore, the present study was designed to develop an understanding of the relationship between stresses in the tooth and the failure potential of the luting agent. Two-dimensional finite element stress analysis was performed on the mandibular second premolar. The behavior of zinc-phosphate and glass-ionomer were studied under different crowns (metal-ceramic and metal crown and loading conditions (mechanical force of 450 N acting vertically over the occlusal surface, thermal loads of 60° and 0°C. It was observed from the study that failure threshold of the luting agent was influenced both by the elastic modulus of the luting agent and by the type of the crown.

  11. Fungicide seed treatment and host resistance for the management of wheat crown rot caused by Fusarium culmorum

    Directory of Open Access Journals (Sweden)

    Shree R Pariyar

    2014-11-01

    Full Text Available Seed treatment of wheat with the fungicide thiabendazole on the development of crown rot caused by Fusarium culmorum was evaluated on six wheat genotypes with different genetic sources of resistance under controlled conditions in a growth chamber. Seed of three susceptible (S cultivars, Seri 82 (Spring bread wheat, Kiziltan 91 (Winter durum Wheat, and Demir 2000 (Winter bread wheat and three moderately resistant (MR wheat lines, 2-49 (Spring bread wheat, Altay 2000 (Winter bread wheat, and Burbot-6 (Winter bread wheat were treated with thiabendazole at concentrations of 25, 50 and 100 g ai per 100 kg seeds. Thiabendazole seed treatment caused a significant (P< 0.05 reduction in severity of crown rot on 4 out of the 6 wheat genotypes. The highest crown score reduction was recorded on S genotypes Seri 82 and Demir 2000. Thiabendazole at 100 g ai per 100 kg seed gave the highest CS reduction on both the S and MR wheat genotypes. Seed coating with thiabendazole did not show any effect on plant height, plant weight, root length and root weight. No phytotoxicity symptoms were observed at any concentration of the fungicide.

  12. Bis[(18-crown-6-κ6Osodium] (18-crown-6-1κ6O-μ-thiocyanato-1:2κ2S:N-pentathiocyanato-2κ5N-indate(IIIsodium 1,2-dichloroethane sesquisolvate

    Directory of Open Access Journals (Sweden)

    Lingqian Kong

    2009-11-01

    Full Text Available The title complex, [Na(C12H24O6]2[InNa(NCS6(C12H24O6]·1.5C2H4Cl2, has been synthesized by the reaction of 18-crown-6 with InCl3 and NaSCN. The In atom has a six-coordinate octahedral environment, being bonded to the N atoms of six thiocyanate groups. The bond lengths and angles show normal values. The crystal packing exhibits no significantly short intermolecular contacts.

  13. PVC-Membrane Electrodes Based on 18-Crown-6 and Dibenzo-18-Crown-6 Ethers for Determination of Silver

    OpenAIRE

    ZAREH, Mohsen Mousa; AKL, Magda A.; and, Ahmd Khlil GOHNEIM

    2007-01-01

    PVC-membrane electrodes for Ag+ based on either 18-crown-6 (I) or di-benzo-18-crown-6 ether (II) were applied for the first time. The effect of solvent mediator on the electrode performance was discussed. Nernstian slope values were 59 and 58.9 mV/decade for both I and II electrode types, respectively. The linear concentration range was 10-5-10-1M. The detection limit was 7.9 \\times 10-6 M. The working pH ranges were 5-9 or 4-9, depending on the concentration of Ag+ ion. The electr...

  14. Significance of crown-down root canal preparation technique in endodontic therapy by using the hydroxylapatite sealer

    Directory of Open Access Journals (Sweden)

    Teodorović Nevenka

    2005-01-01

    Full Text Available Aim.To evaluate the crown-down preparation technique, and the use of hydroxylapatite based material for the definitive root canal obturation. Methods. The investigation included 20 single-canal roots with chronic periapical inflammatory lesion. Biomechanical medicamentous canal preparation was done using the double flared technique with balanced force, and the obturation was performed with hydroxylapatite sealer (unicone technique. Clinical and radiographic check-up performed 12 months after the treatment, used the following parameters: pain, swelling, percussion and palpation sensitivity, and the presence of fistula. Results. The obtained results showed a successful treatment in 18 cases, while in the 2 cases the treatment failed. Conclusion. These findings suggested that the crown-down preparation technique efficiently cleaned and shaped the root canal, and that the hydroxylapatite-based material created the homogenous and hermetic root canal obturation, so this methodology could be recommended for the endodontic therapy.

  15. Automated individual tree crown delineation from LIDAR data using morphological techniques

    International Nuclear Information System (INIS)

    In current tree crown delineation from LiDAR data, treetops and 3D geometric shapes of tree crowns are frequently extracted from LiDAR-derived Crown Height Model (CHM) and used as references to localize and delineate crowns. However, it is difficult to detect deciduous treetops and delineate deciduous tree crowns. The 3D shape of a crown, which can be derived from CHM, may be taken as a half ellipsoid, and any horizontal slice of the ellipsoid contains the treetop and indicates not only the location but also the spatial extent of the crown. Based on such slices, a novel multi-scale method for individual tree crown delineation from CHM was proposed in this study. This method consists mainly of two steps: (1) morphologically open the CHM over the scale range of target tree crowns; and (2) take local maxima within each resulting opened CHM as the horizontal slices of target crowns at the corresponding scale level and integrate all the slices within the scale range together to represent the spatial distribution of target crowns. In an experiment on CHMs over two natural closed canopy forests in Ontario, Canada, the proposed method accurately delineated the majority of the tree crowns from closed canopy forests

  16. Anterior fixed interim prosthesis with natural tooth crown as pontic subsequent to replantation failure

    Directory of Open Access Journals (Sweden)

    Sivakumar Nuvvula

    2011-01-01

    Full Text Available Facial trauma resulting in tooth avulsion results in problems of physical and emotional nature for the patient and a challenge for the dentist. Avulsion accounts for 0.5-16% of traumatic injuries in the permanent dentition that can occur at any age and is most common in the young permanent dentition. As an emergency procedure, it is advisable to replant a traumatically avulsed tooth, but unfortunately long-term success is rather low. After unsuccessful replantation and subsequent extraction, it is prudent to replace the lost tooth to avoid aesthetic, masticatory, and psychological difficulties and also to prevent arch length discrepancy with various alternatives are available for the same. We presented a method for management of one of the two replanted teeth that showed failure, using the natural crown as pontic in a fixed semi-permanent bridge until a more definitive prosthesis can be fabricated at a later age for better patient compliance.

  17. Protonation of benzo-18-crown-6: Extraction and DFT study

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr; Makrlík, E.; Vaňura, P.; Kašička, Václav

    2011-01-01

    Roč. 225, č. 2 (2011), s. 265-270. ISSN 0942-9352 R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40550506 Keywords : protonation * nitrobenzene * benzo-18-crown-6 Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.568, year: 2011

  18. Novel Ordered Crown Ether-Containing Polyimides for Ion Conduction

    Science.gov (United States)

    Irvin, Jennifer A.; Stasko, Daniel; Fallis, Stephen; Guenthner, Andrew J.; Webber, Cynthia; Blackwell, John; Chvalun, Sergei N.

    2003-01-01

    We report the synthesis and characterization of thermally-stable polyimides for use as battery and fuel cell electrolyte membranes. Dianhydrides used were 1,4,5,8- naphthalenetetracarboxylic dianhydride and/or 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Diamines used were anti-4,4-diaminodibenzo-l8-crown-6, 4,4'- diaminodibenzo-24-crown-8, 2,2-bis(4-aminophenyl)hexafluoropropane, and/or 2,5- diaminobenzenesulfonic acid. The polymers were characterized using electrochemical impedance spectroscopy (EIS), thermal analysis and X-ray diffraction. Polymers containing the hexafluoroisopropylidene (HFIP) group were soluble in common organic solvents, while polymers without the HFIP group were very poorly soluble. Sulfonation yields polymers that are sparingly soluble in aqueous base and/or methanol. Degree of sulfonation, determined by titration, was between one and three sulfonate groups per repeat unit. Proton conductivity was determined as a function of water content, with a maximum conductivity of l x 10(exp -2) per centimeter when fully hydrated. Crown ether-containing polymers exhibit a high degree of order that may be indicative of crown ether channel formation, which may facilitate Li(+) transport for use in battery membranes.

  19. Primate molar crown formation times and life history evolution revisited.

    Science.gov (United States)

    Macho, G A

    2001-12-01

    Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life-history variables and brain size. Conversely, a firm relationship between molar formation time and life-history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life-history variables, whereas the other should not. In order to shed light on this apparent discrepancy this study analyzed all data on primate molar crown formations available in the published literature in relation to life-history variables, brain size, and female body mass. Crown formation times were found to be particularly highly correlated with both female body mass and brain size. Species that depart from the overall brain/body allometry by being relatively large-bodied, e.g., Gorilla gorilla and later Theropithecus oswaldi, also have shorter molar crown formation times than expected. The reverse is not found for species that depart from the overall brain/body allometry due to their larger brains, i.e., Homo sapiens. This finding is interpreted within an evolutionary and ecological framework. Specifically, by focusing on ecological commonalities, a scenario is proposed which may allow predictions to be made about the evolutionary history of other extinct primates also. If confirmed in future studies, crown formation time may again become a powerful tool in evolutionary enquiry. PMID:11748692

  20. Restoration of decayed primary incisors using strip crowns.

    Science.gov (United States)

    Pollard, M A; Curzon, J A; Fenlon, W L

    1991-05-01

    Caries of the primary incisors is a common problem that can be arrested if recognized early enough. However, the arrested decay is unsightly. Celluloid 'strip' crown forms, used with composite resin, now allow the restoration of even the most badly decayed primary incisors. The authors describe this quick and efficient technique. PMID:1884866

  1. Displacement of Monolithic Rubble-Mound Breakwater Crown-Walls

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Lars Vabbersgaard; Andersen, Thomas Lykke;

    2012-01-01

    studies on caisson breakwaters, but correction terms are suggested in the present paper to obtain almost equal measured and estimated displacements. This is of great practical importance since many existing rubble-mound crown-walls are subjected to increasing wave loads due to rising sea water level from...

  2. Evolution of the mandibular third premolar crown in early Australopithecus.

    Science.gov (United States)

    Delezene, Lucas K; Kimbel, William H

    2011-06-01

    The Pliocene hominins Australopithecus anamensis and Australopithecus afarensis likely represent ancestor-descendent taxa--possibly an anagenetic lineage--and capture significant change in the morphology of the canine and mandibular third premolar (P(3)) crowns, dental elements that form the canine honing complex in nonhuman catarrhines. This study focuses on the P(3) crown, highlighting plesiomorphic features in A. anamensis. The A. afarensis P(3) crown, in contrast, is variable in its expression of apomorphic features that are characteristic of geologically younger hominins. Temporal variation characterizes each taxon as well. The A. anamensis P(3) from Allia Bay, Kenya expresses apomorphic character states, shared with A. afarensis, which are not seen in the older sample of A. anamensis P(3)s from Kanapoi, Kenya, while spatiotemporal differences in shape exist within the A. afarensis hypodigm. The accumulation of derived features in A. afarensis results in an increased level of P(3) molarisation. P(3) molarisation did not evolve concurrent with postcanine megadontia and neither did the appearance of derived aspects of P(3) occlusal form coincide with the loss of canine honing in hominins, which is apparent prior to the origin of the genus Australopithecus. A. afarensis P(3) variation reveals the independence of shape, size, and occlusal form. The evolution of the P(3) crown in early Australopithecus bridges the wide morphological gap that exists between geologically younger hominins on the one hand and extant apes and Ardipithecus on the other. PMID:21481921

  3. Zinc isotope effects in complex formation with a crown ether

    International Nuclear Information System (INIS)

    Isotope effects for zinc upon complex formation with dicyclohexano-18-crown-6 were investigated. The single stage separation factor for unit mass difference (α = 1.013) was great compared with that of calcium isotopes. One of the isotopes, 67Zn, showed a larger isotope effect than the other isotopes of even mass number. 7 refs., 1 fig

  4. Synthesis of new indolyl crown ethers catalyzed with ferric hydrogensulfate

    Institute of Scientific and Technical Information of China (English)

    Hossein Eshghi; Mohammad Rahimizadeh; Zahra Bakhtiarpoor; Mehdi Pordel

    2012-01-01

    Efficient reaction of bis-indolyl podand with different aldehydes using Fe(HSO4)3 as catalyst to afford the corresponding new indolyl crown ethers is described.The structures of three distinct isomers have been optimized using HyperChem geometry optimizations.Also percentage of each isomer was obtained with 1H NMR spectroscopy.

  5. Application of insertion-type separate inlay crown in the restoration of molar residual roots and crowns with low occlusogingival distance%插销式金瓷嵌体冠在低(牙合)龈距磨牙修复中的应用

    Institute of Scientific and Technical Information of China (English)

    陈勇; 李素贞; 李光武; 陈向琼

    2013-01-01

    Objective To estimate the clinical effect of insertion-type separate porcelain-fused-to-metal inlay crown on molar residual roots and crowns with low occlusogingival distance. Methods Thirty molar residual roots and crowns with low occlusogingival distance (<5 mm) were restored with insertion-type separate porcelain-fused-to-metal inlay crown, which is consist of the porcelain-fused-to-metal inlay crown and cast anatomy inser post. Results During the follow-up of 6~28 months, none of prostheses was loose and fractured. All the prostheses were found with good marginal fitness and well masticatory fuction without sign of gingivitis. Conclusion The insertion-type separate porcelain-fused-to-metal inlay crown is a effective method for restoring molar residual roots and crowns with low occlusogingival distance.%目的 评价插销式金瓷嵌体冠修复低(猞)龈距短冠磨牙的效果.方法 应用金瓷嵌体冠和插销桩一体的插销式金瓷嵌体冠对13例短冠磨牙进行修复.结果 经过6~28个月观察,1 3例插销式金瓷嵌体冠固位良好,均无松动脱落,边缘密合,咀嚼功能良好,无牙龈炎症.结论 插销式金瓷嵌体冠可用于短冠磨牙的修复

  6. Brief communication: Molar development and crown areas in early Australopithecus.

    Science.gov (United States)

    Lacruz, Rodrigo S; Ramirez Rozzi, Fernando V; Wood, Bernard A; Bromage, Timothy G

    2012-08-01

    Recent studies suggest that the hypodigms representing the two earliest Australopithecus (Au. anamensis and Au. afarensis) form an ancestor-descendant lineage. Understanding the details of this possible transition is important comparative evidence for assessing the likelihood of other examples of ancestor-descendant lineages within the hominin clade. To this end we have analyzed crown and cusp base areas of high resolution replicas of the mandibular molars of Au. anamensis (Allia Bay and Kanapoi sites) and those of Au. afarensis (Hadar, Laetoli, and Maka). We found no statistically significant differences in crown areas between these hypodigms although the mean of M(1) crowns was smaller in Au. anamensis, being the smallest of any Australopithecus species sampled to date. Intraspecies comparison of the areas of mesial cusps for each molar type using Wilcoxon signed rank test showed no differences for Au. anamensis. Significant differences were found between the protoconid and metaconid of Au. afarensis M(2)s and M(3)s. Furthermore, the area formed by the posterior cusps as a whole relative to the anterior cusps showed significant differences in Au. afarensis M(1)s and in Au. anamensis M(2)s but no differences were noted for M(3)s of either taxon. Developmental information derived from microstructural details in enamel shows that M(1) crown formation in Au. anamensis is similar to Pan and shorter than in H. sapiens. Taken together, these data suggests that the overall trend in the Au. anamensis-Au. afarensis transition may have involved a moderate increase in M(1) crown areas with relative expansion of distal cusps. PMID:22623291

  7. PEEK Primary Crowns with Cobalt-Chromium, Zirconia and Galvanic Secondary Crowns with Different Tapers—A Comparison of Retention Forces

    Directory of Open Access Journals (Sweden)

    Veronika Stock

    2016-03-01

    Full Text Available In prosthetic dentistry, double crown systems have proved their suitability as retainers for removable partial dentures. However, investigations in this context, regarding polyetheretherketone, are scarce. Therefore, the aim of this study was to test the retention force (RF between polyetheretherketone (PEEK primary and cobalt-chromium (CoCr, zirconia (ZrO2 and galvanic (GAL secondary crowns with three different tapers. Primary PEEK-crowns were milled with the tapers 0°, 1°, and 2° (n = 10/taper, respectively. Afterwards, 90 secondary crowns were fabricated: (i 30 CoCr-crowns milled from Ceramill Sintron (AmannGirrbach, Koblach, Austria (n = 10/taper, (ii 30 ZrO2-crowns milled from Ceramill ZI (AmannGirrbach, Koblach, Austria (n = 10/taper, and (iii 30 GAL-crowns made using electroforming (n = 10/taper. RF was measured in a pull-off test (20 pull-offs/specimen and data were analyzed using 2-/1-way Analysis of Variance (ANOVA followed by the Tukey-Honestly Significant Difference (HSD post hoc test and linear regression analyses (p < 0.05. The measured mean RF values ranged between 9.6 and 38.2 N. With regard to the 0°, 1°, and 2° tapered crowns, no statistically significant differences between CoCr and ZrO2 were observed (p > 0.141. At 0° taper, no differences in retention forces between GAL, CrCr, and ZrO2 crowns were found (p = 0.075. However, at 1° and 2° taper, lower RF for GAL-crowns were observed (p < 0.009, p < 0.001, respectively. According to this laboratory study, PEEK might be a suitable material for primary crowns, regardless of the taper and the material of secondary crown. Long-term results, however, are still necessary.

  8. Supramolecular dimerization of crown-substituted lutetium(3) monophthalocyaninate of the host--guest type

    International Nuclear Information System (INIS)

    The reaction of tetra(15-crown-5)substituted lutetium acetate phthalocyaninate with potassium and sodium acetates in mixed CHCl3-DMSO solvent is investigated by spectrometry and PMR methods. Crown ether fragment of tetra(15-crown-5)substituted lutetium acetate phthalocyaninate was established to chelate of K+ and Na+ ions. As this takes place, the reaction of tetra(15-crown-5)substituted lutetium acetate phthalocyaninate with K+ ions may result in formation of coaxial dimers of host--guest type, whereas assuming the reaction of tetra(15-crown-5)substituted lutetium acetate phthalocyaninate with Na+ the similar dimers have no precedent

  9. Canopy Fuel Load Mapping of Mediterranean Pine Sites Based on Individual Tree-Crown Delineation

    Directory of Open Access Journals (Sweden)

    Giorgos Mallinis

    2013-12-01

    Full Text Available This study presents an individual tree-crown-based approach for canopy fuel load estimation and mapping in two Mediterranean pine stands. Based on destructive sampling, an allometric equation was developed for the estimation of crown fuel weight considering only pine crown width, a tree characteristic that can be estimated from passive imagery. Two high resolution images were used originally for discriminating Aleppo and Calabrian pines crown regions through a geographic object based image analysis approach. Subsequently, the crown region images were segmented using a watershed segmentation algorithm and crown width was extracted. The overall accuracy of the tree crown isolation expressed through a perfect match between the reference and the delineated crowns was 34.00% for the Kassandra site and 48.11% for the Thessaloniki site, while the coefficient of determination between the ground measured and the satellite extracted crown width was 0.5. Canopy fuel load values estimated in the current study presented mean values from 1.29 ± 0.6 to 1.65 ± 0.7 kg/m2 similar to other conifers worldwide. Despite the modest accuracies attained in this first study of individual tree crown fuel load mapping, the combination of the allometric equations with satellite-based extracted crown width information, can contribute to the spatially explicit mapping of canopy fuel load in Mediterranean areas. These maps can be used among others in fire behavior prediction, in fuel reduction treatments prioritization and during active fire suppression.

  10. OsCAND1 Is Required for Crown Root Emergence in Rice

    Institute of Scientific and Technical Information of China (English)

    Xiao-Fei Wang; Fen-Fang He; Xiao-Xia Ma; Chuan-Zao Mao; Charlie Hodgman; Chun-Gui Lu; Ping Wu

    2011-01-01

    Crown roots are main components of the fibrous root system and important for crops to anchor and absorb water and nutrition. To understand the molecular mechanisms of crown root formation,we isolated a rice mutant defective in crown root emergence designated as Oscand1 (named after the Arabidopsis homologous gene AtCAND1). The defect of visible crown root in the Oscand1 mutant is the result of cessation of the G2/M cell cycle transition in the crown root meristem. Map-based cloning revealed that OsCAND1 is a homolog of Arabidopsis CAND1. During crown root primordium development,the expression of OsCAND1 is confined to the root cap after the establishment of fundamental organization. The transgenic plants harboring DR5::GUS showed that auxin signaling in crown root tip is abnormal in the mutant. Exogenous auxin application can partially rescue the defect of crown root development in Oscand1. Taken together,these data show that OsCAND1 is involved in auxin signaling to maintain the G2/M cell cycle transition in crown root meristem and,consequently,the emergence of crown root. Our findings provide new information about the molecular regulation of the emergence of crown root in rice.

  11. Marginal-internal adaptation and fracture resistance of CAD/CAM crown restorations.

    Science.gov (United States)

    Yildiz, Coşkun; Vanlioğlu, Burçin Akoglu; Evren, Buket; Uludamar, Altay; Ozkan, Yasemin Kulak

    2013-01-01

    This study evaluated the marginal adaptation and fracture resistance of CAD/CAM-fabricated zirconia crowns luted using different luting agents. Twenty crown restorations were produced using IPS ZirCAD zirconium oxide blocks (IZC), and another 20 using Lava zirconium oxide blocks (L). Ten teeth were used as control. Luting agents used were an etch-and-rinse adhesive (Variolink II) and a self-etch adhesive (Multilink Automix). Internal and marginal adaptation was evaluated using silicone replica technique. Fracture resistance was evaluated using a compression test. Marginal discrepancy was 89.26 μm for L crowns and 88.84 μm for IZC crowns, and difference was statistically insignificant. However, L crowns showed significantly larger axial and occlusal gaps than IZC crowns (pCAD/CAM-fabricated crowns showed acceptable in vitro marginal discrepancies and fracture strengths. PMID:23370869

  12. Fracture resistance of computer-aided design/computer-aided manufacturing-generated composite resin-based molar crowns.

    Science.gov (United States)

    Harada, Akio; Nakamura, Keisuke; Kanno, Taro; Inagaki, Ryoichi; Örtengren, Ulf; Niwano, Yoshimi; Sasaki, Keiichi; Egusa, Hiroshi

    2015-04-01

    The aim of this study was to investigate whether different fabrication processes, such as the computer-aided design/computer-aided manufacturing (CAD/CAM) system or the manual build-up technique, affect the fracture resistance of composite resin-based crowns. Lava Ultimate (LU), Estenia C&B (EC&B), and lithium disilicate glass-ceramic IPS e.max press (EMP) were used. Four types of molar crowns were fabricated: CAD/CAM-generated composite resin-based crowns (LU crowns); manually built-up monolayer composite resin-based crowns (EC&B-monolayer crowns); manually built-up layered composite resin-based crowns (EC&B-layered crowns); and EMP crowns. Each type of crown was cemented to dies and the fracture resistance was tested. EC&B-layered crowns showed significantly lower fracture resistance compared with LU and EMP crowns, although there was no significant difference in flexural strength or fracture toughness between LU and EC&B materials. Micro-computed tomography and fractographic analysis showed that decreased strength probably resulted from internal voids in the EC&B-layered crowns introduced by the layering process. There was no significant difference in fracture resistance among LU, EC&B-monolayer, and EMP crowns. Both types of composite resin-based crowns showed fracture loads of >2000 N, which is higher than the molar bite force. Therefore, CAD/CAM-generated crowns, without internal defects, may be applied to molar regions with sufficient fracture resistance. PMID:25683749

  13. Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2012-01-01

    Full Text Available Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60 ceramic crowns were made on non-carious extracted human premolars. Thirty (30 crowns were made on the basis of feather-edge preparation (experimental group I. The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany. The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and

  14. FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis.

    Science.gov (United States)

    Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

    2014-01-01

    Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area. PMID:24955150

  15. FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis

    Science.gov (United States)

    Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

    2014-01-01

    Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area. PMID:24955150

  16. Einstein's Length Concept

    International Nuclear Information System (INIS)

    Einstein's length measuring procedure of a rod moving with velocity υ (0 ≤ |υ| < c) is discussed. The part of this procedure, namely measuring the length of the resting (υ = 0) rod, is realizable and leads to the elongation of the moving rod. The other part of Einstein's procedure, measuring the length of the moving (υ ≠ 0) rod, is not realizable and leads to the contraction of the moving rod. As the result of this procedure the moving rod contraction concept is supposed physically unfounded. (author). 8 refs; 1 fig

  17. Success of 6-mm Implants with Single-Tooth Restorations: A 3-year Randomized Controlled Clinical Trial.

    Science.gov (United States)

    Sahrmann, P; Naenni, N; Jung, R E; Held, U; Truninger, T; Hämmerle, C H F; Attin, T; Schmidlin, P R

    2016-06-01

    The aim of the study was to test whether implants of 6 mm in length perform equally well as 10-mm implants in terms of survival and marginal bone-level changes when supporting single crowns. Patients with a posterior single-tooth gap were randomly allocated to either the placement of a 6-mm (test) or 10-mm implant (control). The treatment protocol allowed for internal sinus lift but not for lateral bone augmentation. After a healing period of 10 wk, implants were loaded with screw-retained single crowns. Survival rates, number of pockets ≥5 mm, and bleeding-on-probing were assessed clinically. The change of marginal bone level and crown-to-implant ratios were analyzed by 2 examiners. Longitudinal intragroup analyses for marginal bone levels were performed applying the Wilcoxon signed rank test. Intergroup differences at baseline and at 3 y were compared using the Mann-Whitney U test. The effect of implant length and crown-to-implant ratio on changes of marginal bone level also was determined. Of 94 implants placed (47 test and 47 control), 78 implants (40 test and 38 control) were available for follow-up examination at 3 y of loading. One test implant was lost during the second year. Hence, implant survival was not significantly different between the 2 groups after 3 y (98% test; 100% control). We found no significant change in the crestal bone level from baseline to 3 y for test and control implants with -0.19 ± 0.62 mm and -0.33 ± 0.71 mm, respectively. The intergroup difference was not significant. Crown-to-implant ratios were not associated with a statistically significant difference in marginal bone loss. However, the number of sites with pockets ≥5 mm was significantly higher in the test group. Based on the 3-y assessment, the use of 6-mm implants can be considered a viable option when reconstructing posterior single tooth gaps (German Clinical Trials Registry: DRKS00006290). PMID:26917439

  18. A Characteristic Particle Length

    CERN Document Server

    Roberts, Mark D

    2015-01-01

    It is argued that there are characteristic intervals associated with any particle that can be derived without reference to the speed of light $c$. Such intervals are inferred from zeros of wavefunctions which are solutions to the Schr\\"odinger equation. The characteristic length is $\\ell=\\beta^2\\hbar^2/(8Gm^3)$, where $\\beta=3.8\\dots$; this length might lead to observational effects on objects the size of a virus.

  19. [Application of low noble alloys in telescoped crowns].

    Science.gov (United States)

    Susulić, T

    1989-01-01

    It is known that low noble alloys (Hera SG, Aurea-Heraus, Stabilor-Degussa, Midgold-Bego etc.) are used woredwide for the preparation of prosthetic constructions. For this reason attempts to produce low noble alloys with the properties equal to those of more expensive high noble alloys, are justified, as they are cheap and available to a great number of patients. The Yugoslav producer of dental materials "Zlatarna Celje" has produced a low noble alloy named Midor S. The comparative investigations of resistance to the mouth, performed at the University School of Dentistry in Ljubljana and in the Laboratory of Metallurgy of "Zlatarna Celje", have shown that this alloy was more resistant to corrosion than 22 karat, high noble alloy. In our Department Mikdor S was experimentally tested on telescoped crowns. The obtained results showed the satisfactory hardness and resistance to attrition between the internal and external crowns within the limits of tolerance which made it suitable for use. PMID:2489991

  20. Modeling Tree Crown Dynamics with 3D Partial Differential Equations

    Directory of Open Access Journals (Sweden)

    Robert eBeyer

    2014-07-01

    Full Text Available We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth towards light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

  1. Rayleigh-Plateau instability causes the crown splash

    CERN Document Server

    Deegan, Robert D; Eggers, Jens

    2008-01-01

    The impact of a drop onto a liquid layer and the subsequent splash has important implications for diverse physical processes such as air-sea gas transfer, cooling, and combustion. In the {\\it crown splash} parameter regime, the splash pattern is highly regular. We focus on this case as a model for the mechanism that leads to secondary droplets, and thus explain the drop size distribution resulting from the splash. We show that the mean number of secondary droplets is determined by the most unstable wavelength of the Rayleigh-Plateau instability. Variations from this mean are governed by the width of the spectrum. Our results for the crown splash will provide the basis for understanding more complicated splashes.

  2. Zinc isotope separation with crown ether by column chromatography

    International Nuclear Information System (INIS)

    Depleted 64Zn is a new useful material and can be widely used in the cooling water treatment in light water nuclear power plants. In the present work, column chromatographic zinc isotope separation was performed by crown ether resin which was synthesized by ourselfs, the experimental results shown that benzo-15-crown-5 resin could effectively separate the zinc isotopes. High temperature could improve the separation coefficient, while the migration distance has no effect on separation coefficient. The height equivalent to a theoretical plate increase with the increasing of the migration distance. The separation coefficients (68Zn/64Zn=6.03 x 10-4, 66Zn/64Zn=3.52 x 10-4, respectively) and the height equivalent to a theoretical plate (0.204 cm) were obtained by 20 meters chromatographic operation with the temperature of 328 K. (authors)

  3. Association between PCBs and lower embryonic weight in black-crowned night herons in San Francisco Bay

    Science.gov (United States)

    Hoffman, D.J.; Rattner, B.A.; Bunck, C.M.; Krynitsky, A.J.; Ohlendorf, H.M.; Lowe, R.W.

    1986-01-01

    Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p lt 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = - 0.61; p lt 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching.

  4. Dental ceramics and the molar crown testing ground

    OpenAIRE

    Thompson, P.; Dianne E. Rekow

    2004-01-01

    All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior...

  5. Repertory Migration in the Czech Crown Lands, 1570-1630

    OpenAIRE

    Edwards, Scott Lee

    2012-01-01

    This dissertation studies the production and transmission of musical repertories in the Czech Crown Lands between 1570 and 1630. The region had long been closely linked to bordering lands, but immigration from other countries to the region escalated in the final decades of the sixteenth century with the arrival of the imperial court in Prague, particularly from Spain, Italy, and the Low Lands. The period I have chosen for study thus encompasses this time of unusually intensive travel, migrati...

  6. Mapping of the oat crown rust resistance gene Pc91.

    Science.gov (United States)

    McCartney, C A; Stonehouse, R G; Rossnagel, B G; Eckstein, P E; Scoles, G J; Zatorski, T; Beattie, A D; Chong, J

    2011-02-01

    Crown rust is an important disease of oat caused by Puccinia coronata Corda f. sp. avenae Eriks. Crown rust is efficiently and effectively managed through the development of resistant oat varieties. Pc91 is a seedling crown rust resistance gene that is highly effective against the current P. coronata population in North America. The primary objective of this study was to develop DNA markers linked to Pc91 for purposes of marker-assisted selection in oat breeding programs. The Pc91 locus was mapped using a population of F7-derived recombinant inbred lines developed from the cross 'CDC Sol-Fi'/'HiFi' made at the Crop Development Centre, University of Saskatchewan. The population was evaluated for reaction to P. coronata in field nurseries in 2008 and 2009. Pc91 mapped to a linkage group consisting of 44 Diversity Array Technology (DArT) markers. DArTs were successfully converted to sequence characterized amplified region (SCAR) markers. Five robust SCARs were developed from three non-redundant DArTs that co-segregated with Pc91. SCAR markers were developed for different assay systems, such that SCARs are available for agarose gel electrophoresis, capillary electrophoresis, and Taqman single nucleotide polymorphism detection. The SCAR markers accurately postulated the Pc91 status of 23 North American oat breeding lines. PMID:20862449

  7. Reliability of metalloceramic and zirconia-based ceramic crowns.

    Science.gov (United States)

    Silva, N R F A; Bonfante, E A; Zavanelli, R A; Thompson, V P; Ferencz, J L; Coelho, P G

    2010-10-01

    Despite the increasing utilization of all-ceramic crown systems, their mechanical performance relative to that of metal ceramic restorations (MCR) has yet to be determined. This investigation tested the hypothesis that MCR present higher reliability over two Y-TZP all-ceramic crown systems under mouth-motion fatigue conditions. A CAD-based tooth preparation with the average dimensions of a mandibular first molar was used as a master die to fabricate all restorations. One 0.5-mm Pd-Ag and two Y-TZP system cores were veneered with 1.5 mm porcelain. Crowns were cemented onto aged (60 days in water) composite (Z100, 3M/ESPE) reproductions of the die. Mouth-motion fatigue was performed, and use level probability Weibull curves were determined. Failure modes of all systems included chipping or fracture of the porcelain veneer initiating at the indentation site. Fatigue was an acceleration factor for all-ceramic systems, but not for the MCR system. The latter presented significantly higher reliability under mouth-motion cyclic mechanical testing. PMID:20660796

  8. Surgical crown lengthening: a 12-month study - radiographic results

    Directory of Open Access Journals (Sweden)

    Daniela Eleutério Diniz

    2007-08-01

    Full Text Available OBJECTIVE: The purpose of this study was to perform a radiographic follow-up evaluation after a 12-month healing period, following crown lengthening surgery. MATERIAL AND METHODS: Twenty-three periodontally healthy subjects (mean age 32.5 years that required crown lengthening surgery in premolars were recruited. In a total of 30 premolars, full thickness flaps, osseous resection, and flap suturing were performed. The restorative margin was defined in the pre-surgical phase and maintained unaltered during the healing period, serving as a reference point. Standardized bitewing radiographs were taken before and after osseous reduction, and at 2, 3, 6, and 12-month healing periods. RESULTS: Intact lamina dura was observed at both mesial and distal alveolar crests only from the 3rd month. At 12-months, all alveolar crests presented lamina dura. The overall mean distance from the restorative margin to the alveolar crest achieved after osseous resection was 3.28±0.87 mm at mesial and 2.81±0.51 mm at distal sites. No significant radiographic changes in the bone crest were observed during a 12-month healing period. CONCLUSION: The findings of this study suggest that the radiographic proximal bone level observed on bitewing radiographs following crown lengthening surgery can be used as a reference to predict the future level of the healed alveolar crest.

  9. In vitro study of fracture strength of provisional crown materials

    Science.gov (United States)

    Sayin, Gulsum; Kara, Ozlem

    2015-01-01

    PURPOSE The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. MATERIALS AND METHODS A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at 37℃ for 24 hours, and then they were thermocycled (TC, 5000×, 5-55℃) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (α=.05). RESULTS Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). CONCLUSION Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CAD-CAM technique offers more advantages than the direct technique. PMID:25722834

  10. Shear bond strength of self-ligating orthodontic brackets on different types of porcelain crowns

    Directory of Open Access Journals (Sweden)

    Karamdeep Singh Ahluwalia

    2013-01-01

    Full Text Available Aim: The aim of this study is to compare shear bond strength (SBS and adhesive remnant index (ARI of self-ligating orthodontic brackets bonded to different porcelain crowns. Materials and Methods: Three groups of different types of porcelain crowns, each containing 12 crowns were fabricated by the same technician and allocated to one of the study groups as follows: Group I - IPS porcelain crowns (Ivoclar Vivadent AG, Schaan, Liechtenstein, Group II - Porcelain fused to zirconia crowns (Zirkonzahn GmbH, Gais, Italy, Noritake Co., Tokyo, Japan and Group III - Conventional porcelain fused to metal crowns (Ceramco3, Densply, PA, USA. The orthodontic brackets were bonded to these crowns using hydrofluoric acid (HFA + silane etching protocol. After bonding, the SBS of the brackets were tested with a universal testing machine under standard test conditions. Results: Statistical evaluation using analysis of variance showed a significant difference between the groups (P 0.05. Chi-square comparison revealed no significant difference in ARI scores between groups (P > 0.05. Conclusions: When HFA + silane etching protocol were used, IPS crowns showed the greatest SBS of orthodontic brackets. The ARI score was non-significant. Therefore, if there is a need to place crowns over teeth then these crowns can be used for restoration of teeth before orthodontic treatment.

  11. Aestheric effect of zirconia crown on the anterior tooth%前牙二氧化锆全瓷冠美容修复疗效的临床观察

    Institute of Scientific and Technical Information of China (English)

    毕鹏; 刘宝娟; 张红

    2012-01-01

    目的:探讨二氧化锆全瓷冠在前牙美容修复的临床综合修复效果.方法:选择64例患者的122颗前牙,二氧化锆全瓷冠修复,参照美国公共健康协会的修正标准,对临床结果进行追踪观察1年.结果:122颗二氧化锆全瓷冠在修复完成第1天6项评价指标均达到A级(100%),3个月边缘着色(96.7%)和修复体颜色(96.7%),6个月边缘着色(93.2%)和边缘密合度(98.3%),1年边缘着色(91.4%)和边缘密合度(96.6%).结论:二氧化锆全瓷冠在前牙美学修复中的临床效果较理想.%Objective To investigate the clinical results of zirconia crown on the anterior tooth. Methods All 64 patients treated with zirconia single crowns for 122 anterior teeth,r followed up and after 1 yea. Results The clinical outcome of the 122 all-ceramic zirconia crowns at a rank A in all six aspects betweenO-3months (100%),only four zirconia crowns in marginal color (96.7%) and the color of zirconia crowns (96.7%)in 3 months,eight zirconia crowns in marginal color (93.2%)and two zirconia crowns in marginal fitness (98.3% )in 6 months.ten zirconia crowns in marginal cofor (91.4%)and four zirconia crowns in marginal fitness (96.6%)in 1 year. Conclusion Porcelain-veneered zirconia single crown contribute to the aesthetic effect of the anterior teeth.

  12. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    International Nuclear Information System (INIS)

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of

  13. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    Science.gov (United States)

    Korayem, M. H.; Khaksar, H.; Taheri, M.

    2013-11-01

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of

  14. A Technique to Transfer the Emergence Profile Contours of a Provisional Implant Crown to the Definitive Impression.

    Science.gov (United States)

    Shah, Karnik; Yilmaz, Burak

    2016-01-01

    This clinical report describes a method to create a proper emergence profile and accurately transfer it to the definitive impression, using an indirectly fabricated modified impression post. A provisional screwretained crown was indexed with a polyvinyl siloxane material. An autopolymerizing acrylic resin was used to modify an impression post on the polyvinyl siloxane index, which was then screwed onto the implant for the definitive impression after proper soft tissue healing. The indirectly fabricated modified impression post helped to transfer the contours to the definitive impression with minimal soft tissue irritation. PMID:27004296

  15. Forest Crown Cover Estimation in Northern Boreal and Temperate European Forest

    Science.gov (United States)

    Sirro, Laura; Hame, Tuomas; Ahola, Heikki; Lonnqvist, Anne

    2012-04-01

    A method for forest crown cover estimation using high resolution optical earth observation data was developed and tested at four study sites in Europe. Crown cover was estimated using the probability estimation method of VTT and Image2006 data. The accuracy of the crown cover predictions was assessed using reference data that were collected by visual interpretation of very high resolution aerial and space borne imagery. The average crown cover values in the reference data varied from 17 % to 86 % and in the predictions from 18 % to 80 %. The absolute root mean square error of the crown cover predictions varied between 14 % and 33 %. The results of the study showed that it is possible to map forest crown cover with twenty to thirty meter spatial resolution optical earth observation data using the single pixel values. However, understanding the variable results at different sites requires further investigation.

  16. Stress and Deformation Analysis of Cylinder-Crown Integrated Hydraulic Press with Large Capacity

    Institute of Scientific and Technical Information of China (English)

    Weiwei Zhang; Xiaosong Wang; Zhongren Wang

    2015-01-01

    Cylinder⁃crown integrated hydraulic press ( CCIHP ) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown, which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. In order to design cylinder⁃crown integrated hydraulic press with large capacity, the theoretical design of hemispherical hydraulic cylinder was first proposed, and the structural parameters of 150 MN CCIHP were listed. Then the simulation was carried out to analyze the stress and deformation of CCIHP , and weight comparison was conducted between CCIHP and conventional press. It is shown that the weight reduction for hydraulic cylinder and press crown is about 20%compared with that for conventional press, and the stress and deformation are both within the range of constraints including strength and stiffness conditions. It is possible to manufacture cylinder⁃crown integrated hydraulic press with large capacity.

  17. Fracture Resistance of Non-Metallic Molar Crowns Manufactured with CEREC 3D

    Science.gov (United States)

    Madani, Dalia A.

    Objectives. To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent) (C) and resin composite (Paradigm MZ100, 3M/ ESPE) (R) crowns made with CEREC-3D. Methods. A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of each group were subjected to compressive loading to fracture. The remaining 10 of each group were subjected to mechanical cyclic loading for 500,000 cycles. The survivors were subjected to compressive loading to fracture. Results. No significant difference in mean fracture load was found between the two materials. However, only 30% of the (C) crowns vs. 100% of the (R) crowns survived the cyclic loading test. Conclusions. (R) crowns demonstrated higher fatigue Resistance than (C) crowns in-vitro and might better resist cracking in-vivo.

  18. Model Building of the Initial Crown Effect Rate in 4-High Mill

    Institute of Scientific and Technical Information of China (English)

    Jianzhong XU; Dianyao GONG; Wencai ZHANG; Xianwen CHANG; Xianghua LIU; Guodong WANG

    2005-01-01

    The code for calculating the crown effect rate of hot strip steel was developed using the effect function method.The effect of the initial crown on the crown of the product in hot strip rolling was investigated. The coefficients of a polynomial of degree six for calculating the base value of initial crown effect rate in 4-high mill were determined and the compensation factors of per unit width rolling force, bending force, work roll crown and draft on the initial crown effect rate were given. The difference between the calculation result by established model and theoretical value obtained by effect function method was 4.88 μm when the strip width was 1.85 m.

  19. 长学制临床医学专业学生预防医学社会实践效果评价%The evaluation of preventive medicine practice effect in long-length of schooling clinical medical students

    Institute of Scientific and Technical Information of China (English)

    刘宝花; 康凤娥; 张桂芝; 岳川; 张华明; 王培玉

    2008-01-01

    To evaluate the teaching effect of preventive medicine society practice in long-length of schooling clinical medical students, the 643 students who had taken part in preventive medicine society practice were investigated with questionnaire. After society practice, we found that the students considered society practice strengthen collectivity conception and the basic opinion in preventive medicine, they would like to do health education in patients and public, they thought they got much knowledge in subject design, collecting data, writing paper and analyzing data by computer. Preventive medicine society practice can strengthen the basic opinion in preventive medicine and enhance the basic skill in scientific research for the students, which achieved the previous teaching purpose.%本文采用问卷调查方法,对本校长学制临床医学专业643名学生进行了调查,以评价其预防医学社会实践的教学效果.调查结果显示,预防医学社会实践加强了学生的群体和预防为主的观念;学生毕业后愿意向病人和人群进行健康教育;学生在课题设计、资料收集、论文撰写、计算机处理资料方面有较大收获.预防医学社会实践能够加强学生的预防医学基本观念,全面提高学生科研的基本技能,达到了预期的教学目的.

  20. Comparison of crown fire modeling systems used in three fire management applications

    OpenAIRE

    Scott, J. H.

    2006-01-01

    The relative behavior of surface-crown fire spread rate modeling systems used in three fire management applications—CFIS (Crown Fire Initiation and Spread), FlamMap and NEXUS— is compared using fire environment characteristics derived from a dataset of destructively measured canopy fuel and associated stand characteristics. Although the surface-crown modeling systems predict the same basic fire behavior characteristics (type of fire, spread rate) using the same basic fire environment characte...

  1. Biomechanical three-dimensional finite element analysis of monolithic zirconia crown with different cement type

    OpenAIRE

    Ha, Seung-Ryong

    2015-01-01

    PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimens...

  2. CORRELATION BETWEEN MARGIN FIT AND MICROLEAKAGE IN COMPLETE CROWNS CEMENTED WITH THREE LUTING AGENTS

    OpenAIRE

    Paulo Henrique Orlato Rossetti; Accacio Lins do Valle; Ricardo Marins de Carvalho; Mario Fernando de Goes; Luiz Fernando Pegoraro

    2008-01-01

    Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with e...

  3. Involvement of phenolic compounds in the susceptibility of bananas to crown rot. A review.

    OpenAIRE

    Lassois, L.; de Lapeyre de Bellaire, L; Ewané, CA.; Lepoivre, P

    2012-01-01

    Crown rot of bananas, caused by a fungal parasitic complex, is one of the main quality defects of exported bananas. Major variations in the susceptibility of bananas to crown rot have been observed in different production zones. The physiological state of the banana fruit at harvest is said to influence its response to pathogenic attack and thus to modulate its susceptibility to crown rot. The susceptibility of bananas to this disease, however, appears to be influenced by many pre-harvest fac...

  4. Evaluating the effect of Die spacer on crown retention in fixed prosthesis

    OpenAIRE

    H. Benaz; MH Salari

    1997-01-01

    Crown retention is related to its adaptation with tooth while there is always a gap between the crown and prepared tooth. Although this gap is filled with cements but the mechanical retention between axial walls and internal surfaces is decreased. Therefore, what is the relation between die spacer and crown retention? Does it affect retention? And if so, what is the best thickness of it? It has been a long time that various techniques are recommended and used to improve the ...

  5. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

    Directory of Open Access Journals (Sweden)

    Deborah Pacheco Lameira

    2015-01-01

    Full Text Available The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP crowns in monolithic (1.5 mm thickness and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n=10: Polished monolithic zirconia crowns (PM; Glazed monolithic zirconia crowns (GM; Bi-layer crowns (BL. Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C, and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey’s test (P=.05 indicated that monolithic zirconia crowns presented similar fracture strength (PM=3476.2 N ± 791.7; GM=3561.5 N ± 991.6, which was higher than bilayer crowns (2060.4 N ± 810.6. There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.

  6. A Market-Window Analysis for Crown-Cut Broccoli Produced in Southwest Virginia

    OpenAIRE

    Dillard, John; Kmak, Heather; Russ, M.J.; Coale, Charles W., Jr.; Bratsch, Tony; Reaves, Dixie Watts

    2006-01-01

    This research determines the profitability for farmers of marketing film-wrapped Crown-Cut broccoli in Southwest Virginia. Historical price data was collected in three eastern terminal markets (Atlanta, Baltimore, and Philadelphia) for Crown-Cut and bunched broccoli from October 1998 to January 2005. Cost-of-production budgets were estimated for Crown-Cut broccoli. The economic data was entered into a market window analysis and the profitability of each market was evaluated. The profitability...

  7. An endo-aesthetic management of crown dilaceration in a permanent mandibular central incisor

    OpenAIRE

    Wankhade, Abhijit D; Pandey, Ramesh Kumar; Singh, Rajeev Kumar; Naphade, Milind V

    2013-01-01

    Traumatic injuries to primary dentition may result in a wide range of developmental disturbances to succedaneous permanent teeth. The prevalence of morphological disturbances, secondary to dental injuries in the primary dentition, ranges from 12% to 69%. One of the morphological disturbances are crown dilacerations which are defined as the displacement of a portion of the developing crown at an angle to the longitudinal axis of the tooth. The prevalence of crown dilaceration constitutes 3% of...

  8. Influence of surface treatment and cyclic loading on the durability of repaired all-ceramic crowns

    OpenAIRE

    Ahmed Attia

    2010-01-01

    OBJECTIVE: This study investigated the durability of repaired all-ceramic crowns after cyclic loading. MATERIAL AND METHODS: Eighty In-ceram zirconia crowns were fabricated to restore prepared maxillary premolars. Resin cement was used for cementation of crowns. Palatal cusps were removed to simulate fracture of veneering porcelain and divided into 4 groups (n = 20). Fracture site was treated before repair as follows: roughening with diamond bur, (DB); air abrasion using 50 µm Al2O3, (AA) and...

  9. Aesthetic Rehabilitation of a Complicated Crown-Root Fracture of the Maxillary Incisor: Combination of Orthodontic and Implant Treatment

    Directory of Open Access Journals (Sweden)

    Érica Dorigatti de Avila

    2014-01-01

    Full Text Available The aim of this paper is to present a complex rehabilitation, of fractured tooth, with implants in anterior region considering the orthodontics extrusion to clinical success. At 7 years old, the patient fractured the maxillary left central incisor and the dentist did a crown with the fragment. Twenty years later, the patient was referred to a dental clinic for orthodontic treatment, with the chief complaint related to an accentuated deep bite, and a professional started an orthodontic treatment. After sixteen months of orthodontic treatment, tooth 21 fractured. The treatment plan included an orthodontic extrusion of tooth 21 and implant placement. This case has been followed up and the clinical and radiographic examinations show excellence esthetic results and satisfaction of patient. The forced extrusion can be a viable treatment option in the management of crown root fracture of an anterior tooth to gain bone in a vertical direction. This case emphasizes that to achieve the esthetic result a multidisciplinary approach is necessary.

  10. Sex Identification of Red-crowned Crane by the Polymerase Chain Reaction

    Institute of Scientific and Technical Information of China (English)

    LI Jian-hong; LI Shu-ling; BAO Jun; BAI Xiu-juan

    2004-01-01

    Sex determining gene primers of Oriental White Stork were used to amplify sex-linked gene of the Red-crowned Crane's W chromosome-specific by PCR for sex identification. The sexes of 7 couples of grown Red-crowned Cranes and 15 youngs were identified. Through DNA sequence analysis, the identity is 94.77% between Red-crowned Crane and Oriental White Stork. The results of this study suggest that the application of the polymerase chain reaction technique is practicable for determining sex in the Red-crowned Crane.

  11. Extracting oil palm crown from WorldView-2 satellite image

    International Nuclear Information System (INIS)

    Oil palm (OP) is the most commercial crop in Malaysia. Estimating the crowns is important for biomass estimation from high resolution satellite (HRS) image. This study examined extraction of individual OP crown from a WorldView-2 image using twofold algorithms, i.e., masking of Non-OP pixels and detection of individual OP crown based on the watershed segmentation of greyscale images. The study site was located in Beluran district, central Sabah, where matured OPs with the age ranging from 15 to 25 years old have been planted. We examined two compound vegetation indices of (NDVI+1)*DVI and NDII for masking non-OP crown areas. Using kappa statistics, an optimal threshold value was set with the highest accuracy at 90.6% for differentiating OP crown areas from Non-OP areas. After the watershed segmentation of OP crown areas with additional post-procedures, about 77% of individual OP crowns were successfully detected in comparison to the manual based delineation. Shape and location of each crown segment was then assessed based on a modified version of the goodness measures of Möller et al which was 0.3, indicating an acceptable CSGM (combined segmentation goodness measures) agreements between the automated and manually delineated crowns (perfect case is '1')

  12. LINEAR POLYSILOXANE WITH DIBENZO-18-CROWN-6 MOIETIES AS LIQUID MEMBRANE CARRIER

    Institute of Scientific and Technical Information of China (English)

    GONG Shuling; LU Xueran; LU Xianming; CHEN Yuanyin

    1995-01-01

    A modified method of preparing crown functionalized linear polysiloxane has beendescribed. 4'-Allyldibenzo- 18-crown-6 was subjected to hydrosilylation withmethyldichlorosilane, followed by polycondensation with silanol-terminatedpolydimethylsiloxane to give the title crown functionalized linear polysiloxane. Thetransport properties of sodium, potassium, and ammonium salt through a bulk liquidmembrane system using the new type of crown functionalized linear polysiloxane as acarrier were investigated. It is worthy to point out that the carrier can be used repeatedlyat least six runs with no apparent change in the transport rate of potassium ion.

  13. On the ferrule effect and the biomechanical stability of teeth restored with cores, posts, and crowns

    OpenAIRE

    Mamoun, John S.

    2014-01-01

    An abutment for a fixed partial denture may not contain enough tooth structure, such that the abutment does not provide an adequate ‘ferrule effect’. A crown or bridge dental prosthesis that is cemented onto such an abutment/s may undergo biomechanical failure. Here, the tooth, core, and post complex, on which the crown is cemented, may fracture off from the abutment, causing the crown to separate from the abutment, while the cement that bonds the crown to the tooth, core, and post complex re...

  14. Conductometric study of reaction kinetics between potassium superoxide and 18-crown-6 in dimethylsulfoxide

    International Nuclear Information System (INIS)

    Complexing within KO2-18-crown-6-solvent, KOH-18-crown-6-solvent and KI-KO2-18-crown-6-solvent systems in dimethylsulfoxide was studied by measurement of electrical conductivity. It was shown that time variation of electrical conductivity under the given conditions was described by the Erofeev-Auramy equation, the coefficients of that equation for various systems were determined, time to reach equilibrium state was estimated. Linear dependences of electrical conductivity of KI-KO2 salt solutions at presence of 18-crown-6 at the state of equilibrium in contrast to the component concentrations were determined

  15. Extracting oil palm crown from WorldView-2 satellite image

    Science.gov (United States)

    Korom, A.; Phua, M.-H.; Hirata, Y.; Matsuura, T.

    2014-02-01

    Oil palm (OP) is the most commercial crop in Malaysia. Estimating the crowns is important for biomass estimation from high resolution satellite (HRS) image. This study examined extraction of individual OP crown from a WorldView-2 image using twofold algorithms, i.e., masking of Non-OP pixels and detection of individual OP crown based on the watershed segmentation of greyscale images. The study site was located in Beluran district, central Sabah, where matured OPs with the age ranging from 15 to 25 years old have been planted. We examined two compound vegetation indices of (NDVI+1)*DVI and NDII for masking non-OP crown areas. Using kappa statistics, an optimal threshold value was set with the highest accuracy at 90.6% for differentiating OP crown areas from Non-OP areas. After the watershed segmentation of OP crown areas with additional post-procedures, about 77% of individual OP crowns were successfully detected in comparison to the manual based delineation. Shape and location of each crown segment was then assessed based on a modified version of the goodness measures of Möller et al which was 0.3, indicating an acceptable CSGM (combined segmentation goodness measures) agreements between the automated and manually delineated crowns (perfect case is '1').

  16. On the radiation stability of crown ethers in ionic liquids.

    Energy Technology Data Exchange (ETDEWEB)

    Shkrob, I.; Marin, T.; Dietz, M. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Univ. of Wisconsin at Milwaukee)

    2011-04-14

    Crown ethers (CEs) are macrocyclic ionophores used for the separation of strontium-90 from acidic nuclear waste streams. Room temperature ionic liquids (ILs) are presently being considered as replacements for traditional molecular solvents employed in such separations. It is desirable that the extraction efficacy obtained with such solvents should not deteriorate in the strong radiation fields generated by decaying radionuclides. This deterioration will depend on the extent of radiation damage to both the IL solvent and the CE solute. While radiation damage to ILs has been extensively studied, the issue of the radiation stability of crown ethers, particularly in an IL matrix, has not been adequately addressed. With this in mind, we have employed electron paramagnetic resonance (EPR) spectroscopy to study the formation of CE-related radicals in the radiolysis of selected CEs in ILs incorporating aromatic (imidazolium and pyridinium) cations. The crown ethers have been found to yield primarily hydrogen loss radicals, H atoms, and the formyl radical. In the low-dose regime, the relative yield of these radicals increases linearly with the mole fraction of the solute, suggesting negligible transfer of the excitation energy from the solvent to the solute; that is, the solvent has a 'radioprotective' effect. The damage to the CE in the loading region of practical interest is relatively low. Under such conditions, the main chemical pathway leading to decreased extraction performance is protonation of the macrocycle. At high radiation doses, sufficient to increase the acidity of the IL solvent significantly, such proton complexes compete with the solvent cations as electron traps. In this regime, the CEs will rapidly degrade as the result of H abstraction from the CE ring by the released H atoms. Thus, the radiation dose to which a CE/IL system is exposed must be maintained at a level sufficiently low to avoid this regime.

  17. Unicuspid and bicuspid tooth crown formation in squamates.

    Science.gov (United States)

    Handrigan, Gregory R; Richman, Joy M

    2011-12-15

    The molecular and developmental factors that regulate tooth morphogenesis in nonmammalian species, such as snakes and lizards, have received relatively little attention compared to mammals. Here we describe the development of unicuspid and bicuspid teeth in squamate species. The simple, cone-shaped tooth crown of the bearded dragon and ball python is established at cap stage and fixed in shape by the differentiation of cells and the secretion of dental matrices. Enamel production, as demonstrated by amelogenin expression, occurs relatively earlier in squamate teeth than in mouse molars. We suggest that the early differentiation in squamate unicuspid teeth at cap stage correlates with a more rudimentary tooth crown shape. The leopard gecko can form a bicuspid tooth crown despite the early onset of differentiation. Cusp formation in the gecko does not occur by the folding of the inner enamel epithelium, as in the mouse molar, but by the differential secretion of enamel. Ameloblasts forming the enamel epithelial bulge, a central swelling of cells in the inner enamel epithelium, secrete amelogenin at cap stage, but cease to do so by bell stage. Meanwhile, other ameloblasts in the inner enamel epithelium continue to secrete enamel, forming cusp tips on either side of the bulge. Bulge cells specifically express the gene Bmp2, which we suggest serves as a pro-differentiation signal for cells of the gecko enamel organ. In this regard, the enamel epithelial bulge of the gecko may be more functionally analogous to the secondary enamel knot of mammals than the primary enamel knot. PMID:21932327

  18. Determination of stability constants of K and Cs nitrate complex with dicyclohexyl-18-crown-6 and dibenzo-18-crown-6 in isopropanol aqueous solutions

    International Nuclear Information System (INIS)

    Total stability constants of K and Cs nitrate complexes with dicyclohexyl-18-crown-6 and dibenzo-18-crown-6 in isopropanol aqueous solutions were determined by the method of low-frequency contact conductometry. Clearly defined K/Cs selectivity is observed for the system with dibenzo-18-crown-6. It is shown that lgβ depends on permittivity of the solvent. The decrease of permittivity of isopropanol aqueous solutions results in reduction of K/Cs selectivity of DB18C6

  19. Effect of cements on fracture resistance of monolithic zirconia crowns

    OpenAIRE

    Nakamura, Keisuke; Mouhat, Mathieu; Nergård, John Magnus; Lægreid, Solveig Jenssen; Kanno, Taro; Milleding, Percy; Örtengren, Ulf

    2016-01-01

    Abstract Objectives The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a...

  20. Effect of sandblasting on fracture load of titanium ceramic crowns

    OpenAIRE

    Moldi, Arvind I.; Bhandari, Kishor Singh; Nagral, Sharanbassapa; Deshpandey, Sumit; Kulkarni, Pawan

    2015-01-01

    Purpose of the Study: It is difficult to achieve a reliable bond between the titanium and veneering porcelain. The aim of this study was to evaluate the bond strength between titanium ceramic crowns. Materials and Methods: The surfaces of titanium copings were divided in two groups. Group A sandblasted with 250 um (n = 10) and Group B without sandblasting (n = 10). Low-fusing porcelain was bonded over copings. A universal testing machine was used to determine the fracture load (N) of the crow...

  1. Isotope effects of zinc in crown ether chromatography

    International Nuclear Information System (INIS)

    Isotope separation of zinc has been studied with a polymer-supported crown ether resin packed in glass columns. Chromatography was performed in a break-through manner by feeding a zinc chloride solution into the columns. The mass analysis revealed that the heavier isotope was enriched at the front part of the zinc adsorption band. This result means that the heavier isotopes are preferentially fractionated into the solution phase. The largest single-stage separation coefficient (ε) in the present work is 1.0 x 10-3 for the isotopic pair of 64Zn and 66Zn at 35degC. (author)

  2. The Vitruvius' Tale of Archimedes and the Golden Crown

    OpenAIRE

    Sparavigna, Amelia Carolina

    2011-01-01

    The paper discusses the tale that we can find in "The Architecture" by Vitruvius, on a method used by Archimedes to determine the percentage of gold and silver in a crown. The method is based on the immersion of bodies, allowing the evaluation of their volume in the case of irregular shapes. The measurement, as reported in "The Architecture", seems to be difficult to realize. But, using a vessel for a water-clock, the approach that Vitruvius described is possible. Here the discussion and expe...

  3. The Vitruvius' Tale of Archimedes and the Golden Crown

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    The paper discusses the tale that we can find in "The Architecture" by Vitruvius, on a method used by Archimedes to determine the percentage of gold and silver in a crown. The method is based on the immersion of bodies, allowing the evaluation of their volume in the case of irregular shapes. The measurement, as reported in "The Architecture", seems to be difficult to realize. But, using a vessel for a water-clock, the approach that Vitruvius described is possible. Here the discussion and experiments.

  4. Relativistic length agony continued

    Directory of Open Access Journals (Sweden)

    Redžić D.V.

    2014-01-01

    Full Text Available We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redžić 2008b, we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the ‘pole in a barn’ paradox. [Projekat Ministarstva nauke Republike Srbije, br. 171028

  5. Digital device in postextraction implantology: a clinical case presentation.

    Science.gov (United States)

    Borgonovo, A E; Rigaldo, F; Battaglia, D; Re, D; Giannì, A B

    2014-01-01

    Aim. The aim of this work is to describe a case of immediate implant placement after extraction of the upper right first premolar, with the use of CAD/CAM technology, which allows an early digital impression of the implant site with an intraoral scanner (MHT 3D Progress, Verona, Italy). Case Report. A 46-year-old female was referred with a disorder caused by continuous debonding of the prosthetic crown on the upper right first premolar. Clinically, there were no signs, and the evaluation of the periapical radiograph showed a fracture of the root, with a mesial well-defined lesion of the hard tissue of the upper right first premolar, as the radiolucent area affected the root surface of the tooth. It was decided, in accordance with the patient, that the tooth would be extracted and the implant (Primer, Edierre implant system, Genoa, Italy) with diameter of 4.2 mm and length of 13 mm would be inserted. After the insertion of the implant, it was screwed to the scan abutment, and a scan was taken using an intraoral scanner (MHT 3D Progress, Verona, Italy). The scanned images were processed with CAD/CAM software (Exocad DentalCAD, Darmstadt, Germany) and the temporary crown was digitally drawn (Dental Knowledge, Milan, Italy) and then sent to the milling machine for production with a composite monoblock. After 4 months, when the implant was osteointegrated, it was not necessary to take another dental impression, and the definitive crown could be screwed in. Conclusion. The CAD/CAM technology is especially helpful in postextraction implant for aesthetic rehabilitation, as it is possible to immediately fix a provisional crown with an anatomic shape that allows an optimal healing process of the tissues. Moreover, the removal of healing abutments, and the use of impression copings, impression materials, and dental stone became unnecessary, enabling the reduction of the chair time, component cost, and patient's discomfort. However, it is still necessary for scientific

  6. Digital Device in Postextraction Implantology: A Clinical Case Presentation

    Directory of Open Access Journals (Sweden)

    A. E. Borgonovo

    2014-01-01

    Full Text Available Aim. The aim of this work is to describe a case of immediate implant placement after extraction of the upper right first premolar, with the use of CAD/CAM technology, which allows an early digital impression of the implant site with an intraoral scanner (MHT 3D Progress, Verona, Italy. Case Report. A 46-year-old female was referred with a disorder caused by continuous debonding of the prosthetic crown on the upper right first premolar. Clinically, there were no signs, and the evaluation of the periapical radiograph showed a fracture of the root, with a mesial well-defined lesion of the hard tissue of the upper right first premolar, as the radiolucent area affected the root surface of the tooth. It was decided, in accordance with the patient, that the tooth would be extracted and the implant (Primer, Edierre implant system, Genoa, Italy with diameter of 4.2 mm and length of 13 mm would be inserted. After the insertion of the implant, it was screwed to the scan abutment, and a scan was taken using an intraoral scanner (MHT 3D Progress, Verona, Italy. The scanned images were processed with CAD/CAM software (Exocad DentalCAD, Darmstadt, Germany and the temporary crown was digitally drawn (Dental Knowledge, Milan, Italy and then sent to the milling machine for production with a composite monoblock. After 4 months, when the implant was osteointegrated, it was not necessary to take another dental impression, and the definitive crown could be screwed in. Conclusion. The CAD/CAM technology is especially helpful in postextraction implant for aesthetic rehabilitation, as it is possible to immediately fix a provisional crown with an anatomic shape that allows an optimal healing process of the tissues. Moreover, the removal of healing abutments, and the use of impression copings, impression materials, and dental stone became unnecessary, enabling the reduction of the chair time, component cost, and patient’s discomfort. However, it is still necessary

  7. [Retention of crowns as affected by film thickness of zinc phosphate cement and taper angle of crowns (author's transl)].

    Science.gov (United States)

    Otani, H; Goto, T

    1979-10-01

    Dependence of the retention of crowns at their axial wall on the film thickness of zinc phosphate cement and the taper angle was investigated. Stainless steel dies, composed of a preparation and an occlusally perforated crown the taper angle of which was 2.9, 5.7, 8.5 and 11.3 degrees respectively (Fig. 1, (a) and (b)), were cemented within three min. after the start of mix with a Shofu Micro Cement having a powder-liquid ratio of 1.5 g/0.5 cc. The thickness of the cement layer at the axial wall was regulated to a given value between 9 and 55 mu through the use of a discrepancy measurer. A Shimazu Autograph tensile test machine was employed to measure 48-hr retention (kg/cm2). The retention of the crowns was strongly dependent on the cement film thickness and the taper angle when the film thickness was below a critical value (15 mu in this experiment), but not when the film thickness was above this value (Fig. 3). This may be explained by the term of mechanical interlocking of either of the unreacted powder grains and the matrix phase in the luting cement, as schematically drawn in Fig. 6. The same findings were more evidently appeared on the semilogarythmic diagram in Fig. 4. In this diagram, the critical value was shown as intersection of two straight lines which could be drawn through all the measurements for four taper angles, using the least squares. PMID:295065

  8. Development of high-performance ion sensors based on the functions of crown ethers and synthetic bilayer membranes; Kurauneteru oyobi goseinibunshimaku no kino wo kiban to shita koseino ion denkyoku no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yanagi, H.; Sakai, T.; Ogata, T. [Tokuyama Corp., Tokyo (Japan)

    1999-10-10

    High-Performance Na{sup +}, K{sup +} and Cl{sup -} ion selective electrodes (ISEs) are reported. These are based on a new concept, which is an ion recognition site formed by molecular interaction. In the case of Na and K ISEs, crown ether compounds connecting with planar substituents were used as the ionophores. The selectivities depend on the structure of substituents. It is found that the intermolecular interaction of the planar substituent plays an important role on the improvement of selectivity. The selectivities of interactive mono (crown ether) are equal to that of bis (crown ether). It means that ion recognition site like a bis (crown ether) is formed by the interaction of mono (crown ehter)s. In the case of C1 ISE, immobilized synthetic bilayer membrane with quaternary ammonium salts was used as the ion sensitive membrane. in the immobilized synthetic bilayer membrane, ordered molecular aggregates is formed. It is found that the molecular orientation improved the Cl selectivity. The insufficient selectivity over lipophilic anions can be addition of alphatic alcohol. These resulting ISEs exhibit high speed response and long life time, and they are applicable to clinical use which demands both accurate measurement and high speed processing. (author)

  9. Clergy, nobility and crown in Decadência

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2006-01-01

    Full Text Available In the current work I intend to inquire into the internal motives that led the Portuguese seaborne empire to decadence. After making a brief review of the historiography about the decline of Estado da Índia, I proceed to the analysis of the Crown-Church-Nobility triangle in the course of os Descobrimentos, and of their respective roles in the evolution of Portuguese empire. The absolutization of the crown, the over-expansion of the clergy and the empowerment of the aristocracy became the most conspicuous and longstanding features in the Portuguese social fabric after the country launched herself into maritime undertakings, which crippled her agriculture and retarded the industrialization. As a consequence, the rise of bourgeoisie and the transformation of mercantilist economy into the capitalist were obstructed, and a strong adventurous but non-productive spirit mixed with disdain of manual work prevailed both in metropolis and in overseas territories. In conclusion, the Portuguese decadence commenced from within rather than from without, and far prior to Dutch intrusions in Portuguese Asia, which only accelerated the decline.

  10. Influence of implant angulation with different crowns on stress distribution.

    Science.gov (United States)

    Pellizzer, Eduardo Piza; Falcón-Antenucci, Rosse Mary; de Carvalho, Paulo Sérgio Perri; Sánchez, Daniela Mayumi Inatomi Kavano; Rinaldi, Gabriel Augusto Tozo; de Aguirre, Carolina Calles; Goiato, Marcelo Coelho

    2011-03-01

    The aim of this study was to perform a photoelastic analysis of stress distribution on straight and angulated implants with different crowns (screwed and cemented). Three models were made of photoelastic resin PL-2: model 1: external hexagon implant 3.75×10.00 mm at 0 degrees; model 2: external hexagon implant 3.75×10.00 mm at 17 degrees; model 3: external hexagon implant 3.75×10.00 mm at 30 degrees. Axial and oblique (45 degrees) load (100 N) was applied with a universal testing machine. The photoelastic fringes on the models were recorded with a digital camera and visualized in a graphic software for qualitative analysis. The axial loading generated the same pattern of stress distribution. The highest stresses were concentrated between medium and apical thirds. The oblique loading generated a similar pattern of stress distribution in the models with similar implant angulation; the highest stress was located on the cervical region opposite to implant angulation and on the apical third. It was concluded that the higher the implant angulation, the higher the stress value, independent of crown type. The screwed prostheses exhibited the highest stress concentration. The oblique load generated higher stress value and concentration than the axial load. PMID:21403571

  11. Large acceleration of α-chymotrypsin-catalyzed dipeptide formation by 18-crown-6 in organic solvents

    NARCIS (Netherlands)

    Unen, van Dirk-Jan; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    The effects of 18-crown-6 on the synthesis of peptides catalyzed by α-chymotrypsin are reported. Lyophilization of the enzyme in the presence of 50 equivalents of 18-crown-6 results in a 425-fold enhanced activity when the reaction between the 2-chloroethylester of N-acetyl-L-phenylalanine and L-phe

  12. Investigating assumptions of crown archetypes for modelling LiDAR returns

    NARCIS (Netherlands)

    Calders, K.; Lewis, P.; Disney, M.; Verbesselt, J.; Herold, M.

    2013-01-01

    LiDAR has the potential to derive canopy structural information such as tree height and leaf area index (LAI), via models of the LiDAR signal. Such models often make assumptions regarding crown shape to simplify parameter retrieval and crown archetypes are typically assumed to contain a turbid mediu

  13. Tree crown delineation from high resolution airborne LiDAR based on densities of high points

    NARCIS (Netherlands)

    Rahman, M.Z.A.; Gorte, B.G.H.

    2009-01-01

    Tree detection and tree crown delineation from Airborne LiDAR has been focusing mostly on utilizing the canopy height model (CHM). This paper presents a method for individual tree crown delineation based on densities of high points (DHP) from the high resolution Airborne LiDAR. The DHP method relies

  14. SOLUTION EFFECTS ON CESIUM COMPLEXATION WITH CALIXARENE CROWN ETHERS FROM LIQUID TO SUPERCRITICAL FLUIDS

    Science.gov (United States)

    Calixarene-crown ethers with rigid skeletons are superior to flexible crown ethers for separation of 137Cs from high level waste (HLW). However, this extraction methodology often requires undesirable solvents and the extraction efficiency is strongly dependent on the solvent pol...

  15. Genetic variation between Phytophthora cactorum isolates differing in their ability to cause crown rot in strawberry

    NARCIS (Netherlands)

    Eikemo, H.; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.

    2004-01-01

    Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan, Australia

  16. Distribution of Wave Loads for Design of Crown Walls in Deep and Shallow Water

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck; Andersen, Thomas Lykke

    2014-01-01

    displacements of a crown wall exposed to wave loads with different exceedance probabilities in an overload situation (in this case the loads exceeded by 0.1 % and 1/250 of the incident waves). The comparison is made using the assumption that the Eigenfrequency of the crown wall and breakwater is significantly...

  17. Bis-functionalized fullerene-dibenzo[18]crown-6 conjugate: synthesis and cation-complexation dependent redox behavior.

    Science.gov (United States)

    Smith, Phillip M; McCarty, Amy Lea; Nguyen, Nhu Yen; Zandler, Melvin E; D'Souza, Francis

    2003-07-21

    A one-step synthesis of bis-pyrrolidine functionalized fullerene-dibenzo[18]crown-6 conjugate and its metal cation complexation to the crown ether entity dependent redox behavior is reported. PMID:12877537

  18. sup 113 Cd shielding tensors of cadmium compounds. 6. Single-crystal NMR study of the CdCl sub 2 times 18-crown-6 complex

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, M.A.; Ellis, P.A. (Univ. of South Carolina, Columbia (USA)); Jakobsen, H.J. (Univ. of Aarhus (Denmark))

    1990-02-07

    The {sup 113}Cd chemical shielding tensor and its orientation in the molecular frame have been determined for CdCl{sub 2} {times} 18-crown-6 via a solid-state single-crystal NMR experiment. The shielding tensor elements are found to be {sigma}{sub 33} = {minus}700 ppM, {sigma}{sub 2}2 = 385 ppM, and {sigma}{sub 11} = 414 ppM. The anisotropy and asymmetry parameters are determined to be {Delta}{sigma} = {minus} 1,100 ppM and {eta} = 0.04, respectively. The unique shielding tensor element, {sigma}{sub 22}, lies 2.4{degree} from the 3-fold rotation axis of the crown ligand and was also found to be the most shielded tensor element {sigma}{sub 33}. The structural feature that determines the orientation of {sigma}{sub 33} is found to be the anomalously long Cd-O bond lengths, i.e. 2.75 {angstrom}. The unusually large magnitude of the most shielded tensor element is analyzed in terms of the special geometry and corresponding shielding trend established for a series of cadmium complexes with similar porphyrin and crown ligands. 15 refs., 2 figs., 3 tabs.

  19. Photoelastic Analysis of Fixed Partial Prosthesis Crown Height and Implant Length on Distribution of Stress in Two Dental Implant Systems

    OpenAIRE

    Evandro Portela Figueirêdo; Eder Alberto Sigua-Rodriguez; Marcele Jardim Pimentel; Ana Regina Oliveira Moreira; Mauro Antônio de Arruda Nóbilo; José Ricardo de Albergaria-Barbosa

    2014-01-01

    The aim of this study was to evaluate by photoelastic analysis stress distribution on short and long implants of two dental implant systems with 2-unit implant-supported fixed partial prostheses of 8 mm and 13 mm heights. Sixteen photoelastic models were divided into 4 groups: I: long implant (5 × 11 mm) (Neodent), II: long implant (5 × 11 mm) (Bicon), III: short implant (5 × 6 mm) (Neodent), and IV: short implants (5 × 6 mm) (Bicon). The models were positioned in a circular polariscope assoc...

  20. Use of modified lip repositioning technique associated with esthetic crown lengthening for treatment of excessive gingival display: A case report of multiple etiologies

    Directory of Open Access Journals (Sweden)

    Matheus Bortoluzzi Mantovani

    2016-01-01

    Full Text Available Excessive gingival display during smile can result in compromised esthetics. This study aims to report a case of excessive gingival display with multiple etiologies treated by means of modified lip repositioning technique associated with esthetic crown lengthening. A 23-year-old female patient, with 5-mm gingival display during smile caused by altered passive eruption and hypermobility of the upper lip, underwent the modified lip repositioning technique associated with gingivectomy followed by flap elevation and ostectomy/osteoplasty. Seven months after the second procedure, the patient had her esthetic complaint solved appearing stable in the observation period. The modified lip repositioning technique is an effective procedure employed to reduce gingival display and when associated with esthetic clinical crown lengthening, can appropriately treat cases of gummy smile.

  1. Use of modified lip repositioning technique associated with esthetic crown lengthening for treatment of excessive gingival display: A case report of multiple etiologies.

    Science.gov (United States)

    Mantovani, Matheus Bortoluzzi; Souza, Eduardo Clemente; Marson, Fabiano Carlos; Corrêa, Giovani Oliveira; Progiante, Patrícia Saram; Silva, Cléverson Oliveira

    2016-01-01

    Excessive gingival display during smile can result in compromised esthetics. This study aims to report a case of excessive gingival display with multiple etiologies treated by means of modified lip repositioning technique associated with esthetic crown lengthening. A 23-year-old female patient, with 5-mm gingival display during smile caused by altered passive eruption and hypermobility of the upper lip, underwent the modified lip repositioning technique associated with gingivectomy followed by flap elevation and ostectomy/osteoplasty. Seven months after the second procedure, the patient had her esthetic complaint solved appearing stable in the observation period. The modified lip repositioning technique is an effective procedure employed to reduce gingival display and when associated with esthetic clinical crown lengthening, can appropriately treat cases of gummy smile. PMID:27041845

  2. The effect of ionizing radiation and 12-crown-4 on antioxidant system activity and lipid peroxidation intensity

    International Nuclear Information System (INIS)

    Crown-ether and radiation damage effects are based on free radical pathology accompanied by bioenergetic and redox process disturbance and cellular membrane structural organization alterations. According to its biological action, 12-crown-4 as a characteristic representative of macrocyclic crown-ethers may be related to radiomimetic

  3. Ionic liquid-type crown ether as a novel medium for liquid/liquid extraction of metal ions

    International Nuclear Information System (INIS)

    Dichloro-poly(oxyethylene) was synthesized by chlorination of polyethylene glycol. And it was treated with imidazole and sodium ethoxide to give the 1N,1N'-poly(oxyethyl)-diimidazole, which was then converted to ionic liquid-type crown ether (ILCE) with the reaction of dichloro-poly(oxyethylene). Further, anion of ILCE was exchanged by anion exchange method. Ultimately, we developed a very efficient synthetic pathway for ILCEs which have various physical and chemical characteristics by the modification of polyethylene glycol chain length and anions. 85Sr was successfully extracted into cyclo-bis-{1N,1N'-[(3,6,9- trioxa)-1,11-undecyl]}-diimidazolium chloride {[(3,2)OEtIm][Cl]} phase, but it was not extracted into [(2,2)OEtIm][Cl], [(3,3)OEtIm][Cl] and [(4,3)OEtIm][Cl]. (author)

  4. Determination of radiostrontium in soil samples using a crown ether

    International Nuclear Information System (INIS)

    A simple and rapid method has been developed for the separation and successive determination of total radiostrontium in soil. The method consists of three basic steps: oxalate precipitation to remove bulk potassium, chromatographic separation of strontium from most inactive and radioactive interferences utilizing a crown ether (Sr. Spec, EIChroM Industries, II. USA), oxalate precipitation of strontium to evaluate the chemical yield. Radiostrontium is then determined by liquid scintillation counting of the dissolved precipitate. When 10 g samples of soil are used the sensitivity of the method is about 10 Bq/kg. The chemical yield is about 80%. The separation and determination of radiostrontium can be carried out in about 8 hours. (author)

  5. Automatic Tree-Crown Detection in Challenging Scenarios

    Science.gov (United States)

    Bulatov, Dimitri; Wayand, Isabell; Schilling, Hendrik

    2016-06-01

    In this paper, a new procedure for individual tree detection and modeling is presented. The input of this procedure consists of a normalized digital surface model NDSM, and a possibly error-prone classification result. The procedure is modular so that the functionality, the advantages and the disadvantages for every single module will be explained. The most important technical contributions of the paper are: Employing watershed transformation combined with classification results, applying hotspots detectors for identifying treetops in groups of trees, and correcting NDSM by detecting and geometric reconstruction of small anomalies, such as earth walls. Two minor contributions are made up by a detailed literature research on available methods for individual tree detection and estimation of tree-crowns for clearly identified trees in order to reduce arbitrariness by assigning trees to one of the few types in the output model.

  6. Zinc isotope effects in benzo crown resin by displacement chromatography

    International Nuclear Information System (INIS)

    The isotope effects of zinc were studied by displacement chromatography with a polymer-supported benzo crown resin packed in glass columns. The influence of migration distance on the zinc isotope effect was investigated. Migration distances from one to thirty meters were performed by feeding zinc chloride in dehydrated acetone solvent into the columns. The migration distance was proved to have no effect on the separation coefficient (ε); however, the migration distance clearly affected the slope coefficient (ks). The height equivalent to a theoretical plate (HETP) was variable for each migration distance in the present work. The slope coefficient ks and HETP were 0.035 and 0.29 cm, respectively, at the 30 m chromatographic operation under 298±1 K in the present work. (author)

  7. Vonlays: a conservative esthetic alternative to full-coverage crowns.

    Science.gov (United States)

    McLaren, Edward A; Figueira, Johan; Goldstein, Ronald E

    2015-04-01

    Porcelain veneers have long been a popular restorative option that have evolved into a well-accepted treatment that can be fabricated in various ways. Onlays are another common treatment modality used in contemporary dentistry to restore large areas of decay and to replace old restorations. With the availability of newer high-strength materials such as lithium disilicate and processing technologies like CAD/CAM and heat pressing, dental professionals are now able to produce highly esthetic, high-strength restorations that blend seamlessly with the natural dentition while also withstanding posterior occlusal forces. This has resulted in innovative methods of providing minimally invasive dentistry. One such approach is a combination restoration the authors call a "vonlay," which, as demonstrated in this case report, can be used as an alternative to coverage crowns to restore damaged posterior teeth. PMID:25821940

  8. 4 '-acetyl benzo-15-crown-5 2-naphthyloxyacetyl hydrazone

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan-qing; WEI Tai-bao; ZHANG You-ming; ZONG Guo-qiang

    2004-01-01

    Aryloxyacetic acid and its derivatives often possess many important biological activities.Some of them are used as herbicides and plant-growth regulators. In continuation of our previous work on synthesis and biological activities1,2,3, we decided to design series of compounds containing the aryloxyacetyl group and crown ether to study the variation of bioactivities and the effect of the substituents on the ability of the crown ether to bind metal ions4,5. Recently, we determined related crystal structures6,7,8 , in order to study both bioactivities and coordination behaviour. In view of these encouraging results, the structure of the title compound (Figure 1), was obtained and is reported here.Figure 1 The molecule configuration and atom-numbering schem for the title compound,showing ellipsoids at the 50% probability level.Crystals of the ritle compound, C28H32N2O7, is monoclinic, space group P2(1)/c, a = 8.808(3), b =24.579(7), c =11.984(4), α = 90.00, β = 97.248(6), γ = 90.00, Z = 4, Dx= 1. 313 Mg m-3 ,Mo K α, λ =0.71073 , = 9.5mm-1 , F(000) = 1080, T =293(2) K, R = 0.0594, wR=0.1184 for 2575reflections [I>2 σ (Ⅰ) ] .The title compound adopts a syn-anti conformation, which enables N2-H...O6 intermolecule hydrogen bonds to be formed between centrosymmetrically related molecules. The resulting eight-membered rings join these molecules together as characteristic dimmers.

  9. Effect of electrostatic interaction on thermochemical behavior of 12-crown-4 ether in various polar solvents

    International Nuclear Information System (INIS)

    The enthalpies of solution of 12-crown-4 ether have been measured in chloroform, ethyl acetate, acetone, pyridine, acetonitrile and methanol at 298.15 K. The values of enthalpy of solvation and solute-solvent interaction were determined from the obtained results and similar literature data for 12-crown-4 in solvents of various polarities. It was shown that the certain correlation is observed between the enthalpy of solute-solvent interaction and the squared dipole moment of the solvent molecules for solutions in tetrachlormethane, ethyl acetate, pyridine, acetonitrile, DMF, DMSO and propylene carbonate. This means that the electrostatic interaction of 12-crown-4 with polar solvent molecules contributes significantly to the exothermic effect of solvation. The understated negative value was found for the enthalpy of interaction of 12-crown-4 with acetone that can be connected with domination of low polar conformer of the crown ether in acetone medium. The most negative values of enthalpy of solvation are observed for solutions in chloroform and water because of hydrogen bonding between O-atoms of crown ether and molecules of the indicated solvents. This effect is not observed for methanol. The negative coefficient of pairwise solute-solute interaction in methanol indicates that the effects of solvophobic solute-solute interaction and H-bonding of the ether molecule with chain associates of methanol are not evinced in the thermochemical behavior of 12-crown-4.

  10. Olive Crown Porosity Measurement Based on Radiation Transmittance: An Assessment of Pruning Effect

    Science.gov (United States)

    Castillo-Ruiz, Francisco J.; Castro-Garcia, Sergio; Blanco-Roldan, Gregorio L.; Sola-Guirado, Rafael R.; Gil-Ribes, Jesus A.

    2016-01-01

    Crown porosity influences radiation interception, air movement through the fruit orchard, spray penetration, and harvesting operation in fruit crops. The aim of the present study was to develop an accurate and reliable methodology based on transmitted radiation measurements to assess the porosity of traditional olive trees under different pruning treatments. Transmitted radiation was employed as an indirect method to measure crown porosity in two olive orchards of the Picual and Hojiblanca cultivars. Additionally, three different pruning treatments were considered to determine if the pruning system influences crown porosity. This study evaluated the accuracy and repeatability of four algorithms in measuring crown porosity under different solar zenith angles. From a 14° to 30° solar zenith angle, the selected algorithm produced an absolute error of less than 5% and a repeatability higher than 0.9. The described method and selected algorithm proved satisfactory in field results, making it possible to measure crown porosity at different solar zenith angles. However, pruning fresh weight did not show any relationship with crown porosity due to the great differences between removed branches. A robust and accurate algorithm was selected for crown porosity measurements in traditional olive trees, making it possible to discern between different pruning treatments. PMID:27213391

  11. Effect of Different Luting Agents on the Retention of Lithium Disilicate Ceramic Crowns

    Directory of Open Access Journals (Sweden)

    Nicola Mobilio

    2015-04-01

    Full Text Available No studies are available that evaluate the retention of disilicate crowns according to different cementation procedures. The purpose of this study was to measure the retention of lithium disilicate crowns cemented using two different cementation systems. Twenty extracted mandibular premolars were prepared. Anatomic crowns were waxed and hot pressed using lithium disilicate ceramic. Teeth were divided into two groups (n = 10: (1 self-curing luting composite and (2 glass-ionomer cement (GIC. After cementation, the crowns were embedded in acrylic resin block with a screw base. Each specimen was pulled along the path of insertion in Universal Testing Machine. Failure load in Newtons (N and failure mode were recorded for each specimen. Failure mode was classified as decementation or fracture. Failure load data were analyzed using one-way analysis of variance (ANOVA. Failure modes were compared using Pearson’s Chi-square test. Mean failure load was 306.6(±193.8 N for composite group and 94.7(±48.2 N for GIC group (p = 0.004. Disilicate crown cemented with luting composite most often failed by fracture; otherwise, crown cemented with glass-ionomer cement most often failed by decementation (p = 0.02. Disilicate full crown cemented with luting composite showed higher failure load compared with conventional cementation with glass-ionomer cement.

  12. Unsupervised individual tree crown detection in high-resolution satellite imagery

    Science.gov (United States)

    Skurikhin, Alexei N.; McDowell, Nate G.; Middleton, Richard S.

    2016-01-01

    Rapidly and accurately detecting individual tree crowns in satellite imagery is a critical need for monitoring and characterizing forest resources. We present a two-stage semiautomated approach for detecting individual tree crowns using high spatial resolution (0.6 m) satellite imagery. First, active contours are used to recognize tree canopy areas in a normalized difference vegetation index image. Given the image areas corresponding to tree canopies, we then identify individual tree crowns as local extrema points in the Laplacian of Gaussian scale-space pyramid. The approach simultaneously detects tree crown centers and estimates tree crown sizes, parameters critical to multiple ecosystem models. As a demonstration, we used a ground validated, 0.6 m resolution QuickBird image of a sparse forest site. The two-stage approach produced a tree count estimate with an accuracy of 78% for a naturally regenerating forest with irregularly spaced trees, a success rate equivalent to or better than existing approaches. In addition, our approach detects tree canopy areas and individual tree crowns in an unsupervised manner and helps identify overlapping crowns. The method also demonstrates significant potential for further improvement.

  13. A ferric-cyanide-bridged one-dimensional dirhodium complex with (18-crown-6)potassium cations.

    Science.gov (United States)

    Kim, Y; Kim, S J; Nam, W

    2001-03-01

    The crystal structure of the title compound, catena-poly[bis[aqua(18-crown-6)potassium] diaqua(18-crown-6)potassium [[tetra-mu-benzoato-2:3 kappa(8)O:O'-mu-cyano-1:2 kappa(2)C:N-tetracyano-1 kappa C-irondirhodium(Rh-Rh)]-mu-cyano-1 kappa C:3' kappa N] octahydrate], [K(18-crown-6)(H(2)O)](2)[K(18-crown-6)(H(2)O)(2)][FeRh(2)(C(7)H(5)O(2))(4)(CN)(6)] x 8H(2)O, where (18-crown-6) is 1,4,7,10,13,16-hexaoxacyclooctadecane (C(12)H(24)O(6)), has been determined. Ferric cyanides connect the dirhodium units to form a one-dimensional chain compound. [K(18-crown-6-ether)(H(2)O)(2)] cations (with inversion symmetry) and [K(18-crown-6-ether)(H(2)O)] cations (in general positions) are located between the chains. PMID:11250572

  14. Crown color match of implant-supported zirconia and Porcelain-Fused-to-Metal restorations:

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana;

    2014-01-01

    Objectives: The aim of the present study was to compare the crown color match of implant supported zirconia restorations and Porcelain-Fused-to-Metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. Materials and Methods: Eighteen patients with 29 implant-supporte......Objectives: The aim of the present study was to compare the crown color match of implant supported zirconia restorations and Porcelain-Fused-to-Metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. Materials and Methods: Eighteen patients with 29 implant......-supported single crowns in anterior maxillary area were recruited, 11 of the implant crowns were zirconia restorations and 18 were PFM restorations. Color match of the implant crown with contra-lateral/neighboring tooth at the position of body 1/3 of the crown were assessed using spectrophotometer (Spectro......ShadeTM, Micro Dental) in CIEL¿a¿b¿ coordinates. Subjective crown color match scores were evaluated. Independent sample t test of SPSS17.0 was used to compare the difference between zirconia restoration and PFM restoration. Spearman correlation was used to analyze the relationship between the spectrophotometric...

  15. Clinical outcome of a two-piece implant system with an internal hexagonal connection: a prospective study.

    Science.gov (United States)

    Andreasi Bassi, M; Lopez, M A; Confalone, L; Gaudio, R M; Lombardo, L; Lauritano, D

    2016-01-01

    The purpose of this prospective clinical study was to evaluate the survival rate (SVR - i.e. fixtures still in place at the end of the observation period) and success rate (SCR - i.e. bone resorption around implant neck) of an implant system characterized by cylindrical and tapered implants, both provided with an internal hexagonal connection. In the period between January 1996 and October 2011, 52 implants with internal hexagonal connection were inserted in 21 females and 31 males, mean age 54±11 years. The mean post-surgical follow-up was 44.6±34.4 months. Several parameters were evaluated as potential outcome conditioners: age, gender, smoking, replaced tooth, periodontal disease, fixture shape (i.e. cylindrical or tapered), jaw location (i.e. maxilla or mandible), bone graft, immediate loading, post-extractive placement, type of prosthesis (i.e. single crown or bridge), edentulism, implant diameter and length. An SPSS statistical program was used and Cox regression analysis performed. SVR was 100% since no fixtures were lost. SCR, expressed through the mean marginal bone loss, was 77%. No significant differences were found, for most of the parameters analyzed, with the exception of prosthetic bridges, where implants supporting this type of rehabilitation showed a worse clinical outcome in comparison to single crown rehabilitations. Internal hexagonal connection is a reliable tool for oral rehabilitation. PMID:27469542

  16. Cs(I) transport studies employing Calix-crown-6 ligands dissolved in phenyl trifluoro methyl sulphone

    International Nuclear Information System (INIS)

    Cs(I) transport was investigated from acidic feeds employing flat sheet supported liquid membranes containing several calix-crown-6 ligands, viz., with calix(4)arene-bis-18-crown-6 (CC), calix(4)arene-bis-1,2-benzo-crown-6 (CBC), calix(4)arene-bis-2,3-naphtho-crown-6 (CNC), (bis-octyloxy)calix(4)arene-mono-crown-6 (CMC) dissolved in Phenyl Trifluoro Methyl Sulphone (PTMS). The transport of the metal ion followed the trend: CBC ∼ CC > CNC > CMC. Co-transport of nitric acid was found to affect the metal ion transport rates at higher feed acidities. (author)

  17. MnBr2/18-crown-6 coordination complexes showing high room temperature luminescence and quantum yield.

    Science.gov (United States)

    Hausmann, David; Kuzmanoski, Ana; Feldmann, Claus

    2016-04-12

    The reaction of manganese(ii) bromide and the crown ether 18-crown-6 in the ionic liquid [(n-Bu)3MeN][N(Tf)2] under mild conditions (80-130 °C) resulted in the formation of three different coordination compounds: MnBr2(18-crown-6) (), Mn3Br6(18-crown-6)2 () and Mn3Br6(18-crown-6) (). In general, the local coordination and the crystal structure of all compounds are driven by the mismatch between the small radius of the Mn(2+) cation (83 pm) and the ring opening of 18-crown-6 as a chelating ligand (about 300 pm). This improper situation leads to different types of coordination and bonding. MnBr2(18-crown-6) represents a molecular compound with Mn(2+) coordinated by two bromine atoms and only five oxygen atoms of 18-crown-6. Mn3Br6(18-crown-6)2 falls into a [MnBr(18-crown-6)](+) cation - with Mn(2+) coordinated by six oxygen atoms and Br - and a [MnBr(18-crown-6)MnBr4](-) anion. In this anion, Mn(2+) is coordinated by five oxygen atoms of the crown ether as well as by two bromine atoms, one of them bridging to an isolated (MnBr4) tetrahedron. Mn3Br6(18-crown-6), finally, forms an infinite, non-charged [Mn2(18-crown-6)(MnBr6)] chain. Herein, 18-crown-6 is exocyclically coordinated by two Mn(2+) cations. All compounds show intense luminescence in the yellow to red spectral range and exhibit remarkable quantum yields of 70% (Mn3Br6(18-crown-6)) and 98% (Mn3Br6(18-crown-6)2). The excellent quantum yield of Mn3Br6(18-crown-6)2 and its differentiation from MnBr2(18-crown-6) and Mn3Br6(18-crown-6) can be directly correlated to the local coordination. PMID:26956783

  18. Evaluation of different sterilization and disinfection methods on commercially made preformed crowns.

    Science.gov (United States)

    Yilmaz, Y; Guler, C

    2008-12-01

    The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM). Preformed crowns (NuSmile Primary Anterior Crown (NSC), Kinder Krowns (KK), Pedo Pearls (PP) and polycarbonate crowns (PC)) were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group); steam autoclaving at 134 degrees C (30 psi) for 4 min (G2); steam autoclaving at 134 degrees C (30 psi) for 12 min (G3); steam autoclaving at 121 degrees C (15 psi) for 30 min (G4); and ultrasonication in a bath containing 4% Lysetol AF for 5 min at room temperature (chemical disinfection) (G5). Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05) crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients. PMID:19008625

  19. Evaluation of different sterilization and disinfection methods on commercially made preformed crowns

    Directory of Open Access Journals (Sweden)

    Yilmaz Y

    2008-01-01

    Full Text Available The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM. Preformed crowns (NuSmile Primary Anterior Crown (NSC, Kinder Krowns (KK, Pedo Pearls (PP and polycarbonate crowns (PC were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group; steam autoclaving at 134 °C (30 psi for 4 min (G2; steam autoclaving at 134 °C (30 psi for 12 min (G3; steam autoclaving at 121 °C (15 psi for 30 min (G4; and ultrasonication in a bath containing 4% Lysetol ® AF for 5 min at room temperature (chemical disinfection (G5. Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05 crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

  20. Evaluation of various Crown ethers for the supercritical fluid extraction of uranium from nitric acid medium

    International Nuclear Information System (INIS)

    Various crowns have been evaluated for supercritical fluid extraction of uranium from nitric acid medium employing HPFOA as counter ion. Uranium extraction efficiency was found to be influenced by cavity size of crown ether and nature of substituents. Complexation tendency of UO22+ increases with increasing cavity size of crown ether. Electron withdrawing substituents decreased the extraction efficiency which could be attributed to decrease in the basicity of four oxygen atoms and hence their bonding ability. Whereas electron donating substituents increased the efficiency due to increases in basicity of oxygen atoms and hence in increase in bonding ability. (author)

  1. QTL analysis of crown rust resistance in perennial ryegrass under conditions of natural and artificial infection

    DEFF Research Database (Denmark)

    Schejbel, Britt; Jensen, Louise Friis Bach; Xing, Yongzhong; Lübberstedt, Thomas

    2007-01-01

    Crown rust is an economically devastating disease of perennial ryegrass. Both artificial crown rust inoculations, with the possibility of several selection cycles in one year, as well as marker-assisted selection can be used for more efficient breeding of new resistant cultivars. The objective of...... years as well as by artificial pathogen inoculations using a detached leaf assessment. The broad sense heritability values for the field, detached leaf and combined assays were 0.42, 0.56, and 0.64, respectively, indicating a good potential for selection for crown rust resistance. A total of six QTLs...

  2. Strength of CAD/CAM-generated esthetic ceramic molar implant crowns

    OpenAIRE

    Wolf, D; Bindl, A; Schmidlin, P R; Lüthy, H; Mörmann, W H

    2008-01-01

    PURPOSE: One-visit in-office CAD/CAM fabrication of esthetic ceramic crowns as a superstructure for posterior implants is quite new. The aim of the study was to evaluate the strength of esthetic ceramic CAD/CAM crowns with varied occlusal thickness and seated with adhesive and nonadhesive cements on titanium and zirconia abutments. MATERIALS AND METHODS: Esthetic ceramic CAD/CAM-generated molar crowns (n = 15 per group) with occlusal thicknesses of 0.5 mm and 1.5 mm were seated on titanium (1...

  3. Were king Stefan the First-Crowned and his son Radoslav co-rulers?

    OpenAIRE

    Bubalo Đorđe

    2009-01-01

    The Serbian historiography considers the issue of the co-ruling of King Stefan the First-Crowned and his son Radoslav as the one finally resolved. The suggested solution on the co-rule of Stefan and Radoslav may be most succinctly expressed as following: as early as in the year of 1220, due to the frail health of Stefan the First-Crowned and Radoslav's marriage to Anne the Epirus princess, Radoslav was crowned to be the king and positioned to co-rule with his father after the Byzantine model ...

  4. Internal fit of two all-ceramic systems and metal-ceramic crowns

    OpenAIRE

    Leandro Moura Martins; Fabio Cesar Lorenzoni; Alcides Oliveira de Melo; Luciana Mendonça da Silva; de OLIVEIRA, José Luiz G.; Pedro Cesar Garcia de Oliveira; Gerson Bonfante

    2012-01-01

    OBJECTIVES: The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. MATERIAL AND METHODS: Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns wa...

  5. Wave Forces and Overtopping on Crown Walls of Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Pedersen, Jan

    series in the coastal laboratory at Aalborg University. Based on analyses of experimental data a design method for assessing the maximum wave forces on the vertical face of the crown wall structures has been developed as well as new and more versatile design equation for the related overtopping...... stability of rubble mound breakwater crown walls. This background motivated the initialization of the present study on wave imposed forces and wave overtopping on crown wall structures. The two subjects where investigated through an excessive parametric model study involving more than 370 long duration test...

  6. Supercritical fluid extraction of uranium from nitric acid employing crown ether

    International Nuclear Information System (INIS)

    Selective extraction and separation of uranium from various matrices is imperative due to its importance as nuclear fuel material. Supercritical fluid extraction of uranium from nitric acid medium employing CO2 as supercritical fluid and di-tert-butyldibenzo-18-crown-6 as co-solvent has been investigated. PFOA was employed as counter ion. Effects of various parameters e.g. pressure, temperature, time of extraction, acidity of medium, metal-to-crown and crown- to-counter ion ratio, on extraction efficiency were examined. Under optimized condition, an extraction efficiency of (58±5)% was obtained. (author)

  7. Possible applications of crown-ethers to metal extraction using liquid membrane technology - a literature survey

    International Nuclear Information System (INIS)

    Ether-crowns, discovered in 1967 by J.C. PEDERSEN, exhibit attractive complexive and extractive properties, enhanced in various fields, such as analytical chemistry, chemical synthesis, field of biology, or extractive chemistry. The investigations carried out on these macrocyclic compounds are continually increasing, as show in international literature. Among the focus of interest, the applications to metal extraction are extensively studied with crown compounds present in liquid phase or impregnated on supports (membranes or resins). The goal of this paper is to describe the application of crown-ethers to metal extraction, using liquid membrane processes. 69 refs

  8. Distribution and prevalence of crown rot pathogens affecting wheat crops in southern Chile

    OpenAIRE

    Ernesto Moya-Elizondo; Nolberto Arismendi; María Paz Castro; Herman Doussoulin

    2015-01-01

    Crown rot pathogens are associated with higher losses for wheat crop farmers, but information about the distribution and prevalence of these pathogens in Chile is inadequate. Distribution and prevalence of wheat (Triticum aestivum L.) crown rot pathogens were examined in a survey of 48 commercial fields from December 2011 to February 2012 in southern Chile. These fields were located between Collipulli (37°56'00" S; 72°26'39" W) and Purranque (40°50'30" S; 73°22'03" W). Severity of crown rot d...

  9. Online recovery of radiocesium from soil, cellulose and plant samples by supercritical fluid extraction employing crown ethers and calix-crown derivatives as extractants

    International Nuclear Information System (INIS)

    Two crown ethers (CEs) viz. dibenzo18crown6, and dibenzo12crown7 and three calix-crown derivatives viz. (octyloxy)calix[4]arene-mono-crown-6 (CMC), calix[4]arene-bis(o-benzocrown-6) (CBC), and calix[4]arene-bis(naphthocrown-6) (CNC) were evaluated for the recovery of 137Cs from synthetic soil, cellulose (tissue paper), and plant samples by supercritical fluid extraction (SFE) route. CEs showed poor extraction of 137Cs from soil matrix. SFE experiments using 1 × 10-3 M solutions of CMC, CBC and CNC in acetonitrile at 3 M HNO3 as modifiers displayed better extraction of 137Cs, viz. 21(±2) % (CMC), 16.5(±3) % (CBC), and 4(±1) % (CNC). It was not possible to recover 137Cs quantitatively from soil matrix. The inefficient extraction of 137Cs from soil matrix was attributed to its incorporation into the interstitial sites. Experiments on tissue papers using CMC showed near quantitative 137Cs recovery. On the other hand, recovery from plant samples varied between 50(±5) % (for stems) and 75(±5) % (for leaves). (author)

  10. Effect of ultrasonic instrumentation on the bond strength of crowns cemented with zinc phosphate cement to natural teeth. An in vitro study

    Directory of Open Access Journals (Sweden)

    Antonio Braulino de Melo Filho

    2008-09-01

    Full Text Available Several studies have reported the benefits of sonic and/or ultrasonic instrumentation for root debridement, with most of them focusing on changes in periodontal clinical parameters. The present study investigated possible alterations in the tensile bond strength of crowns cemented with zinc phosphate cement to natural teeth after ultrasonic instrumentation. Forty recently extracted intact human third molars were selected, cleaned and stored in physiologic serum at 4°C. They received standard preparations, at a 16º convergence angle, and AgPd alloy crowns. The crowns were cemented with zinc phosphate cement and then divided into four groups of 10 teeth each. Each group was then subdivided into two subgroups, with one of the subgroups being submitted to 5,000 thermal cycles ranging from 55 ± 2 to 5 ± 2°C, while the other was not. Each group was submitted to ultrasonic instrumentation for different periods of time: group 1 - 0 min (control, group 2 - 5 min, group 3 - 10 min, and group 4 - 15 min. Tensile bond strength tests were performed with an Instron testing machine (model 4310. Statistical analysis was performed using ANOVA and Tukey's test at the 5% level of significance. A significant reduction in the tensile bond strength of crowns cemented with zinc phosphate and submitted to thermal cycles was observed at 15 min (196.75 N versus 0 min = 452.01 N, 5 min = 444.23 N and 10 min = 470.85 N. Thermal cycling and ultrasonic instrumentation for 15 min caused a significant reduction in tensile bond strength (p < .05.

  11. Functional-aesthetic treatment of crown fracture in anterior teeth with severe crowding

    Directory of Open Access Journals (Sweden)

    Diego Henrique da Silva Mendonça

    2012-09-01

    Full Text Available Introduction: Traumatic injuries are usually the result of impacts whose aggressive strength exceeds the resistance found in bone, muscle and tooth tissues. With the advent of the etching technique and considering the improvement of composite resins, simpler and more conservative alternatives are indicated in the aesthetic and functional rehabilitation of fractured anterior teeth. Case report and objective: This study aimed to report the treatment of a 13 year-old patient that fractured his central incisor due to a trauma. After clinical and radiographic examination, an oblique crown fracture with extensive involvement of the incisal angle, without pulp exposure or injury to the biological space of the left maxillary central incisor (tooth #21 was observed. Because the fractured tooth fragment was lost, it was not possible to process a fragment bonding. Thus, it was proposed to treat the tooth through direct technique restoration with composite resin. Conclusion: It can be concluded that the aesthetic and functional rehabilitation with direct composite resin is a viable option for the conservative treatment of fractured anterior teeth.

  12. Insufficient evidence on whether to restore root-filled teeth with single crowns or routine fillings.

    Science.gov (United States)

    McReynolds, David; Duane, Brett

    2016-06-01

    Data sourcesMedline, Cochrane Oral Health Groups Trials Register, Cochrane Central Register of Controlled Trials, Embase, CINAHL, LILACS.Study selectionThree authors independently assessed the abstracts of studies resulting from the above searches which compared indirect restorations of single endodontically treated teeth (ETT) to direct restoration of single ETT.Data extraction and synthesisTitles and abstracts of all reports identified through the electronic searches were assessed independently by two authors with any disagreements on eligibility resolved by a third reviewing author based on agreed upon inclusion and exclusion criteria. Study quality was assessed using the Cochrane risk of bias tool. Catastrophic failure of the restored tooth or restoration leading directly to extraction was the primary outcome measure. Secondary outcome measures included patient quality of life, incidence of recurring caries, periodontal health status and cost of the use of different interventions. Data analysis was carried out using the, 'treatment as allocated', patient population, expressing estimates of intervention effect for dichotomous data as risk ratios, with 95% confidence intervals (CI).ResultsOne trial which was judged to be at high risk of performance, detection and attrition bias was included. There was no clear difference between the crown and composite group and the composite only group for non-catastrophic failures of the restoration (1/54 versus 3/53; RR 0.33; 95% CI 0.04 to 3.05) or failures of the post (2/54 versus 1/53; RR 1.96; 95% CI 0.18 to 21.01) at three years. The quality of the evidence for these outcomes was judged to be very low. There was no evidence available for any secondary outcomes.ConclusionsInsufficient evidence exists to assess the effects of crowns compared to conventional fillings for the restoration of root-filled teeth. Until more evidence becomes available, clinicians should continue to base decisions about how to restore root

  13. Synthesis of New Chiral Calix [ 4 ] crown Containing (R)-Cys-teine

    Institute of Scientific and Technical Information of China (English)

    HE Yong-Bing; XIAO Yuan-Jing; MENG Ling-Zhi; WU Cheng-Tai

    2001-01-01

    Three new chiral heterocalix[4] crowns containing aza thio atoms bearing two chiral sites provided by (R)-cysteine ester were synthesized.All new compounds were characterized by 1H NMR, MS and elemental analysis .

  14. Study on the thermochemical properties of crown ether and europium (III) guest-host complexes

    International Nuclear Information System (INIS)

    Three novel guest-host complexes formed by Eu(NO3)3·6H2O and benzo-15-crown-5, 4'-formyl benzo-15-crown-5 and 4'-nitro benzo-15-crown-5 were synthesized and identified by elemental analysis, IR and 1HNMR etc. They are 1:1 type coordinated complexes. Their thermochemical properties were studied by TGA method. It was found that the substituted group adhered on the 4'-position of the benzo-ring may influence the bonding strength of the Eu(III) ion with the crown ether as well as the thermal decomposition procedure of the complexes. It has been interpreted by structural chemical principles that the effect of formyl group is stronger than that of the nitro group

  15. 18-Crown[6]ether functionalized reduced graphene oxide for membrane-free ion selective sensing

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    The focus of this work is on the synthesis of a 1-Aza-18-crown[6]ether functionalized reduced graphene oxide (RGO-crown[6]) with specific K+ binding sites on the RGO surface. Glassy carbon electrodes (GCE) functionalized with RGO-crown[6] weretested for selective potentiometric sensing of K+ , with...... a detection limit of 10-5 M without inference from other ions (Na+ , Li+ , NH4+ and Ca2+) in concentrations up to 2.5 × 10-2 M. Similar sensing was achieved with functionalized disposable SPE electrodes. The results demonstrate that RGO-crown[6] is a conductive material full of promise for...... application in fabrication of new types of ion selective sensors....

  16. Studies on the Synthesis and Complexing Behavior of Crown Ethers with External Coordination Center

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The synthesis, characterization of five ditopic or tritopic crown compounds were reported in this paper together with the preparation of the corresponding hetero-dinuclear and hetero-trinuclear complexes with different metal cations.

  17. SYNTHESIS, COMPLEXATION BEHAVIOR AND REACTIONS OF THIA-CROWN ETHERS INCORPORATING PROPAN-2-ONE UNITS

    NARCIS (Netherlands)

    KELLOGG, RM; VANBOLHUIS, F

    1991-01-01

    Thia-crown ethers containing ketone functionality derived from 1,3-dichloroacetone have been prepared in 70-80% yields; the crystal structures of one free macrocycle and two Ag1 complexes have been determined.

  18. Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

    Science.gov (United States)

    Trifkovic, B.; Budak, I.; Todorovic, A.; Hodolic, J.; Puskar, T.; Jevremovic, D.; Vukelic, D.

    2012-01-01

    The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

  19. Functionalization of oxidized single-walled carbon nanotubes with 4-benzo-9-crown-3 ether

    Indian Academy of Sciences (India)

    Ardeshir Khazaei; Maryam Kiani Borazjani; Khadijeh Mansouri Moradian

    2012-09-01

    Functionalization of oxidized single-walled carbon nanotubes (SWCNTs) by a zwitterionic interaction (COO−NH$^{+}_{3}$) between protonated amine on crown ether and an oxyanion from a carboxylic acid group on SWCNT has been described. This ionic interaction has led to a considerable increase in the solubility of SWCNTs in both organic and aqueous solvents such as ethanol, dimethyl sulphoxide, dimethylformamide, and H2O. The highest solubility was attained in DMF and DMSO. The ionic bonded 4-benzo-9-crown-3 ether allowed the hosting of Li+. The ionic bond of crown ether (4-(benzo-9-crown-3)) to SWCNT was identified and confirmed by infrared spectroscopy, transmission electron-microscopy, atomic force microscopy and thermogravimetric analysis methods.

  20. Crown ethers as synergistic agents in the solvent extraction of trivalent lanthanides with 8-hydroxyquinoline

    Directory of Open Access Journals (Sweden)

    M. ATANASSOVA

    2008-01-01

    Full Text Available The liquid extraction of the 13 lanthanides with mixtures of 8-hydroxyquinoline (HQ and crown ethers (S dibenzo-18-crown-6 (DB18C6 and dibenzo-24-crown-8 (DB24C8 in 1,2-dichloroethane as a diluent from chloride medium at constant ionic strength μ = 0.1 was investigated. The composition of the extracted species was established as LnQ3 with HQ alone and as LnQ3·S in the presence of a crown ether. The values of the equilibrium constants were calculated. The addition of DB18C6 to the metal chelate system improved the extraction efficiency, while a weak synergistic enhancement was found when the metals were extracted with mixtures of HQ–DB24C8. The parameters of the extraction process were determined and the separation factors between two adjacent lanthanides(III were calculated.

  1. Application of Crown-Flatness Vector Analysis in Plate Rolling Schedule

    Institute of Scientific and Technical Information of China (English)

    HU Xian-lei; WANG Zhao-dong; JIAO Zhi-jie; ZHAO Zhong; LIU Xiang-hua; WANG Guo-dong

    2004-01-01

    A simple plate crown model was introduced, and the crown-flatness vector analysis method was analyzed. Based on the plate rolling technology, the rolling schedule design of elongation phase is divided into three steps. First step is to calculate the reductions of first pass of elongation making full use of the mill capability to decrease the total pass number. The second step is to calculate the pass reduction for the last three or four passes to control crown and flatness by crown-flatness vector analysis method. In the third step, the maximum rolling force limit and the total pass number are adjusted to make the plate gauge at exit equal to target gauge with satisfactory flatness. The on-line application shows that this method is effective.

  2. Differential Self-Assembly of Novel Redox Crown Ethers

    Science.gov (United States)

    Merithew, Andrew William

    Retinal prosthesis relies on the stimulation of living nerve tissue behind the rods and cones of the eye. The current state of the art relies on electrodes controlled by cameras which directly stimulate the nerve tissue to elicit a response to an image. These types of retinal implants have allowed for short-term crude vision in patients but have had limited long term success due to external battery packs and electroplating of the implanted electrodes. Ionic stimulation is one of the principle mechanisms that sensory neurons utilize in the generation of an action potential. In a complex transduction pathway, ionic gradients are constantly altered inside the neuron by voltage sensors or mechanically controlled gates embedded in the neuronal cell membrane; responsible for the open and close state of these ion channels. It has been demonstrated that local concentration increases of K + by direct injection proximal to the nerve can elicit nerve firing at a concentration of 15-20 mM (3-4X normal concentration) increase in K + concentration. As part of a larger concept of integrating biotechnology with nanofabrication, the materials for the development of potassium selective sequestration/storage and delivery were developed in the form of a redox-gated K+ selective crown ether. The structure of the anthraquinone-based crown was deduced by computational simulation and stoichiometry of the complex confirmed by mass spec. along with 2D diffusion NMR techniques. In this instance, the stoichiometry could be controlled by the addition of different salts to give a 1:1 complex with large, aromatic anions and a 2:1 complex with smaller anions such as triflate. The synthesis of the molecule was optimized by computational modeling and simulations of transport through an artificial membrane. The selectivity of the architecture developed was specific for K+ over Na+, the other major ionic species present in the blood. The mechanism influencing the self-assembly of this class of

  3. Crown fracture of the mandibular second primary molars in a 4-year-old child

    OpenAIRE

    Deshpande, Anshula; Patel, Jalark; Sujan, Sunanda Gul; Mallikarjuna, Rachappa

    2013-01-01

    Dental traumas are highly prevalent lesions in primary teeth, but crown root fractures are rare. Mostly anterior tooth segment is more commonly involved. Posterior crown root fractures are very rare. A 4-year-old girl reported to our paediatric dentistry department with a 10-day history of severe pain and discomfort in both right and left posterior teeth region. The child was suffering from severe and continuous pain and was unable to chew food. After an examination a fracture was noticed in ...

  4. Management of horizontal crown fracture caused by traumatic injury with endorestoration treatment

    OpenAIRE

    Nanik Zubaidah

    2011-01-01

    Background: Traumatic injuries of teeth are the main cause of emergency treatment in dental practice. The horizontal crown fracture more frequently observed usually occurs in maxillary anterior region and young male patients. The most common type of coronal fracture is in the middle third, followed by root and apical part. Purpose: The aim of this case report is to present the management of crown fracture of teeth with pulp exposure caused by dental trauma with endorestoration treatment in or...

  5. Procedure for selective solvent extraction of superheavy elements 113+ and 1142+ by use of crown ethers

    International Nuclear Information System (INIS)

    Solvent extraction of Pb2+ and Ba2+ with 18-crown-6 ethers from a solution containing Ce3+, Zn2+ and UO22+ ions in the presence of sodium picrate was studied. The results allow to suggest the use of crown ethers as a selective reagent for the separation of elements having ionic radii near to those predicted for the superheavy elements 113+ and 1142+. This extraction may be also used for continuous chemical separations in accelerator experiments. (orig.)

  6. Single implant and crown versus fixed partial denture: A cost-benefit, patient-centred analysis.

    Science.gov (United States)

    Goodacre, Charles J; Naylor, W Patrick

    2016-01-01

    Single implants and their crowns have high survival rates that exceed the survival rates for fixed partial dentures on teeth and most but not all publications have determined single implants are more cost-effective than 3-unit fixed partial dentures. Both initial root canal treatment and retreatment are more cost-effective than tooth extraction and rehabilitation with a single implant and crown. PMID:27314112

  7. Uncertainties of forest area estimates caused by the minimum crown cover criterion

    OpenAIRE

    Magdon, Paul; Kleinn, Christoph

    2012-01-01

    Defining “forest land” is a complex issue and has been discussed for decades. Today, a confusing multitude of definitions of forest land are in use making comparison of forest area figures difficult. But currently, comparability is receiving much attention when it comes to install market mechanisms for ecosystem services. Minimum crown cover is among the most frequently employed criteria of forest definitions. However, the size of the reference area on which the crown cover percent is to be m...

  8. Distribution and prevalence of crown rot pathogens affecting wheat crops in southern Chile

    Directory of Open Access Journals (Sweden)

    Ernesto Moya-Elizondo

    2015-03-01

    Full Text Available Crown rot pathogens are associated with higher losses for wheat crop farmers, but information about the distribution and prevalence of these pathogens in Chile is inadequate. Distribution and prevalence of wheat (Triticum aestivum L. crown rot pathogens were examined in a survey of 48 commercial fields from December 2011 to February 2012 in southern Chile. These fields were located between Collipulli (37°56'00" S; 72°26'39" W and Purranque (40°50'30" S; 73°22'03" W. Severity of crown rot disease was determined through visual assessment of the first internode of 20 tillers obtained from each field. Incidence of crown rot pathogens per field was determined by plating the 20 tillers on Petri plates with 20% potato dextrose agar amended with lactic acid (aPDA medium. Resulting fungal colonies from monoxenic culture were identified by morphological or molecular-assisted identification. Severity of crown rot varied between 11.3% and 80% for individual fields. Culture plate analysis showed 72.2% of stems were infected with some fungus. Fusarium avenaceum, F. graminearum, and F. culmorum, pathogens associated with Fusarium crown rot disease were isolated from 13.5% of tillers. Gaeumannomyces graminis, causal agent of take-all disease in cereals, was isolated from 11.1% of culms. Phaeosphaeria sp., an endophyte and possibly a non-pathogenic fungus, was isolated from 13.9% of tillers. Pathogenic fungi such as Rhizoctonia spp. and Microdochium nivale, other saprophyte, and several unidentified non-sporulating fungi were isolated at frequencies lower than 3% of the total. Fusarium crown rot and take-all were the most prevalent and distributed crown rot diseases present in wheat crops in southern Chile.

  9. Movements of a juvenile Crowned Eagle (Harpyhaliaetus coronatus) tracked by satellite telemetry in central Argentina

    OpenAIRE

    Urios, Vicente; Donat-Torres, María Pilar; Bechard, Mark; Ferrer, Miguel

    2014-01-01

    Background: A juvenile Crowned Eagle was tagged at its nest with a satellite transmitter. The Crowned Eagle (Harpyhaliaetus coronatus) is one of the most unknown raptor species from the American continent. Their current distribution ranges from central Brazil to central Argentina, with a total population of 350 1500 individuals across this large area, being thus largely fragmented. Results: During the three years of tracking the bird concentrated its movements in a range spanning ...

  10. Influence of application site of provisional cement on the marginal adaptation of provisional crowns

    Directory of Open Access Journals (Sweden)

    Mayra Cardoso

    2008-06-01

    Full Text Available INTRODUCTION: Marginal discrepancies may lead to cement washout and marginal leakage, damaging periodontal and pulp tissues or causing premature loss of the restoration. PURPOSE: This study evaluated the influence of application site of provisional cement on the marginal adaptation of provisional crowns. MATERIAL AND METHODS: Four different application sites of provisional cement (Temp Bond NE, Kerr Corporation were used for cementation of provisional crowns on phantom teeth prepared for full crown restorations, performing 4 experimental groups (n=10: cement applied to all internal surfaces of the crown (CAO; cement applied to all internal surfaces of the crown, except for the occlusal surface (CA; cement applied to the cervical crown margin (CM; and cement applied to the cervical tooth margin (TM. A comparison microscope (Mitutoyo America Corporation was used to measure the distances between the internal tangents of two circular marks, one made on the provisional crown and one made apical to the tooth preparation margin, in areas corresponding to buccal, lingual, mesial and distal surfaces. Marginal adaptation was determined before and after cementation, with 0.0001-mm accuracy. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. RESULTS: Mean values of marginal opening obtained for each group were: CAO: 145 µm; CA: 67 µm; CM: 46 µm; TM: 34 µm. CA, CM and TM presented significantly lower marginal openings than CAO (p<0.05. CONCLUSION: complete filling of the crown with provisional cement, including the occlusal surface, provided grater marginal discrepancies when compared to the other methods evaluated.

  11. INFLUENCE OF APPLICATION SITE OF PROVISIONAL CEMENT ON THE MARGINAL ADAPTATION OF PROVISIONAL CROWNS

    OpenAIRE

    Mayra Cardoso; Marcelo Ferreira Torres; Mariana Ribeiro de Moraes Rego; Luiz Carlos Santiago

    2008-01-01

    INTRODUCTION: Marginal discrepancies may lead to cement washout and marginal leakage, damaging periodontal and pulp tissues or causing premature loss of the restoration. PURPOSE: This study evaluated the influence of application site of provisional cement on the marginal adaptation of provisional crowns. MATERIAL AND METHODS: Four different application sites of provisional cement (Temp Bond NE, Kerr Corporation) were used for cementation of provisional crowns on phantom teeth prepared for ful...

  12. Management of Complicated Crown Fracture with Miniature Pulpotomy: A Case Report

    OpenAIRE

    Asgary, Saeed; Fazlyab, Mahta

    2014-01-01

    Crown fractures account for the majority of dental traumas. If handled properly, prognosis of the pulp following a traumatic crown fracture can be favorable. The present case report focuses on the treatment of a traumatized mature permanent incisor with exposed pulp that was treated with the novel technique of miniature pulpotomy using calcium-enriched mixture (CEM) cement. One-year follow-up revealed that the tooth was responsive to vitality tests and radiographic assessment showed the prese...

  13. Design and Development of Automated Coconut Dehusking and Crown Removal Machine

    OpenAIRE

    Venkataramanan Segar; Abhinav Ram B; Rahul R.

    2014-01-01

    This paper presents the design and analysis activities involved in developing an automated coconut de-husking and coconut crown removal machine. The main purpose of this machine is to eliminate the skilled operator involved in de-husking the coconut and to completely automate the dehusking and crown removing process. Although coconut dehusking machines have already been demonstrated in the work [1,3,4] and also in some small scale industries, the process is either manual or semiautomatic. A c...

  14. Genetic variation between Phytophthora cactorum isolates differing in their ability to cause crown rot in strawberry

    OpenAIRE

    Eikemo, H; Klemsdal, S.S.; Riisberg, I.; Bonants, P.J.M.; Stensvand, A.; Tronsmo, A.M.

    2004-01-01

    Analysis of 44 isolates of Phytophthora cactorum, isolated from strawberry and other hosts, by AFLP showed that the crown rot pathotype is different from leather rot isolates and from P. cactorum isolated from other hosts. 16 of 23 crown rot isolates, including isolates from Europe, Japan, Australia, and New Zealand, were identical in an analysis based on 96 polymorphic bands from seven primer combinations. Leather rot isolates of strawberry could not be distinguished from isolates from other...

  15. CAD/CAM fabricated single-unit all-ceramic post–core–crown restoration

    OpenAIRE

    Thilla Sekar Vinothkumar; Deivanayagam Kandaswamy; Pallavi Chanana

    2011-01-01

    This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post-core-crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM) technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a sin...

  16. Synergistic solvent extraction of crown ether complexes with alkali metal picrates by neutral donor solvents

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y.

    1983-09-01

    The solvent extraction of rubidium and cesium picrates has been studied at 25/sup 0/C with mixtures of crown ether and tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) in benzene, and the adduct-formation constants in the benzene solution have been calculated. The crown ethers used in this work were 12-crown-4 (12C4), 15-crown-5 (15C5), and benzo-15-crown-5 (B15C5). The stoichiometric composition of any extracted complex under the present experimental conditions is alkali metal ion : crown ether : TBP or TOPO : picrate ion = 1 : 1 : 1 : 1. The TOPO complex is more extractable than the corresponding TBP complex. The extractability of the Rb/sup +/ complex is larger than that of the corresponding Cs/sup +/ complex. For both TBP and TOPO, the adduct-formation constant value sequences of Rb/sup +/ and Cs/sup +/ are B15C5 > 12C4 > 15C5 and 12C4 > B15C5 > 15C5, respectively. 2 figures, 1 table.

  17. In vitro failure of crowns produced by two CAD/CAM systems.

    Science.gov (United States)

    Donnelly, Thomas J; Burke, F J Trevor

    2011-09-01

    Previous laboratory studies have demonstrated satisfactory fracture resistance of all-ceramic crowns placed using a resin-composite luting material and a dentine bonding system. This study investigated the fracture resistance of teeth restored using CAD/CAM technology, namely, Zirconia Based crowns and Cerec produced feldspathic porcelain crowns, both luted with a self adhesive resin luting material (RelyX Unicem Clicker 3M ESPE). Standardized preparations were carried out on two groups often sound, unrestored, maxillary premolar teeth. Ceramic crowns were constructed to have a thickness of 2mm at their midline fissure. Compressive fracture resistance was determined for each group using a Universal Testing Machine. The failure modes were also examined visually and interpreted according to a chosen scale. Mean Compressive fracture resistance of 746 (147)N and 1630 (175)N were recorded for the Cerec and Lava groups respectively; differences were statistically significant (p Lava crowns is significantly greater than a similar group of teeth restored with Cerec crowns. PMID:22645792

  18. Distribution of Lepidopteran Larvae on Norway Spruce: Effects of Slope and Crown Aspect.

    Science.gov (United States)

    Kulfan, Ján; Dvořáčková, Katarína; Zach, Peter; Parák, Michal; Svitok, Marek

    2016-04-01

    Lepidoptera associated with Norway spruce, Picea abies (L.) Karsten, play important roles in ecosystem processes, acting as plant pests, prey for predators, and hosts for parasites and parasitoids. Their distribution patterns in spruce crowns and forests are only poorly understood. We examined how slope and crown aspect affect the occurrence and abundance of moth larvae on solitary spruce trees in a montane region in Central Europe. Moth larvae were collected from southern and northern crowns of trees growing on south- and north-facing slopes (four treatments) using emergence boxes at the end of winter and by the beating method during the growing season. Species responses to slope and crown aspect were not uniform. Treatment effects on moth larvae were stronger in the winter than during the growing season. In winter, the abundance of bud-boring larvae was significantly higher in northern than in southern crowns regardless of the slope aspect, while both slope and aspect had marginally significant effects on abundance of miners. During the growing season, the occurrence of free-living larvae was similar among treatments. Emergence boxes and beating spruce branches are complementary techniques providing valuable insights into the assemblage structure of moth larvae on Norway spruce. Due to the uneven distribution of larvae detected in this study, we recommend adoption of a protocol that explicitly includes sampling of trees from contrasting slopes and branches from contrasting crown aspect in all seasons. PMID:26795212

  19. Supercritical carbon dioxide extraction of uranium from acidic medium employing crown ethers

    International Nuclear Information System (INIS)

    Supercritical carbon dioxide (SC CO2) extraction of uranium from nitric acid medium employing various crown ethers was studied. CO2-phillic C-F bonds in pentadecafluoro-n-octanic acid (HPFOA) counter ion enhanced the extraction efficiency. Pressure (100-300 atm) and temperature (323-353 K) were found to influence extraction efficiency by affecting SC CO2 density as well as due to large size cluster formation of supercritical fluid near critical point thereby resulting in reduced interaction with solute. Pressure of 200 atm and temperature of 323 K were found to be optimum. The trend in efficiency for benzo substituted crown ethers was due to the combined effect of cavity size and number of ether oxygen atoms. The extraction efficiency among 18-crown-6 series is influenced by the extent of basicity of ether oxygen, which in turn is dictated by the substituent group. Efficiency also decreased beyond 2 M nitric acid due to co-extraction of crown-nitric acid complex. Uranium: crown: HPFOA mole ratio influenced extraction efficiency, having optimum value at 1: 10: 100. Under optimized conditions with ditertiarybutyldicyclohexano-18-crown-6 the efficiency was found to be (86 ± 5)%. (orig.)

  20. Effect of cement types on the tensile strength of metallic crowns submitted to thermocycling.

    Science.gov (United States)

    Consani, Simonides; Santos, Julie Guzela dos; Correr Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho; Sousa-Neto, Manoel Damião

    2003-01-01

    The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10 masculine tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types. PMID:15057396

  1. Crystal structure of cis-anti-cis-dicyclohexane-18-crown-6 acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Alexander Nazarenko

    2015-07-01

    Full Text Available The title compound (systematic name: cis-anti-cis-2,5,8,15,18,21-hexaoxatricyclo[20.4.0.09,14]hexacosane acetonitrile disolvate, C20H36O6·2CH3CN, crystallizes from an acetonitrile solution of dicyclohexane-18-crown-6 on evaporation. The molecule is arranged around a center of symmetry with half the crown ether molecule and one molecule of acetonitrile symmetry independent. All O—C—C—O torsion angles are gauche while all C—O—C—C angles are trans. The sequence of torsion angles is [(tg+t(tg−t]3; the geometry of oxygen atoms is close to pseudo-D3d with three atoms below and three atoms above the mean plane, with an average deviation of ±0.16 (1 Å from the mean plane. This geometry is identical to that observed in metal ion complexes of dicyclohexane-18-crown-6 but differs significantly from the conformation of a free unsolvated molecule. Each acetonitrile molecule connects to a crown ether molecule via two of its methyl group H atoms (C—H...O. Weaker interactions exist between the third H atom of the acetonitrile methyl group and an O atom of a neighbouring crown ether molecule (C—H...O; and between the N atom of the acetonitrile molecule and a H atom of another neighbouring crown ether molecule. All these intermolecular interactions create a three-dimensional network stabilizing the disolvate.

  2. Evaluation of polymer inclusion membranes containing crown ethers for selective cesium separation from nuclear waste solution

    International Nuclear Information System (INIS)

    Transport behaviour of 137Cs from nitric acid feed was investigated using cellulose triacetate plasticized polymer inclusion membrane (PIM) containing several crown ether carriers viz. di-benzo-18-crown-6 (DB18C6), di-benzo-21-crown-7 (DB21C7) and di-tert-butylbenzo-18-crown-6 (DTBB18C6). The PIM was prepared from cellulose triacetate (CTA) with various crown ethers and plasticizers. DTBB18C6 and tri-n-butyl phosphate (TBP) were found to give higher transport rate for 137Cs as compared to other carriers and plasticizers. Effect of crown ether concentration, nitric acid concentration, plasticizer and CTA concentration on the transport rate of Cs was also studied. The Cs selectivity with respect to various fission products obtained from an irradiated natural uranium target was found to be heavily dependent on the nature of the plasticizer. The present work shows that by choosing a proper plasticizer, one can get either good transport efficiency or selectivity. Though TBP plasticized membranes showed good transport efficiency, it displayed poor selectivities. On the other hand, an entirely opposite separation behaviour was observed with 2-nitrophenyloctylether (NPOE) plasticized membranes suggesting the possible application of the later membranes for the removal of bulk 137Cs from the nuclear waste. The stability of the membrane was tested by carrying out transport runs for nearly 25 days.

  3. Crystal structures of dioxonium hexafluorotantalate and dioxonium hexafluoroniobate complexes with tetrabenzo-30-crown-10

    International Nuclear Information System (INIS)

    Two isostructural complexes of dioxonium [H5O2]+ with tetrabenzo-30-crown-10 of the compositions [(tetrabenzo-30-crown-10 · H5O2)][TaF6] (I) and [(tetrabenzo-30-crown-10 · H5O2)][NbF6] (II) are studied using X-ray diffraction. The complexes crystallize in the monoclinic crystal system (space group C2/c, Z = 4). The unit cell parameters of these compounds are as follows: a = 15.6583(12) Å, b = 15.2259(13) Å, c = 16.4473(13) Å, and β = 99.398(6)° for complex I and a = 15.7117(12) Å, b = 15.2785(15) Å, c = 16.5247(15) Å, and β = 99.398(7)° for complex II. These complexes belong to the ionic type. The dioxonium cation [H5O2]+ in the form of the two-unit cluster [H3O · H2O]+ is stabilized by the strong hydrogen bond OH⋯O [O⋯O, 2.353(4) Å] and encapsulated by the crown ether. Each oxygen atom of the dioxonium cation also forms two oxygen bonds O⋯O(crown). The crown ether adopts an unusual two-level (pocket-like) conformation, which provides a complete encapsulation of the oxonium associate. The interaction of the cationic complex with the anion in the crystal occurs through contacts of the C-H⋯F type.

  4. Development of the aza-crown ether metal complexes as artificial hydrolase.

    Science.gov (United States)

    Yu, Lan; Li, Fang-zhen; Wu, Jiao-yi; Xie, Jia-qing; Li, Shuo

    2016-01-01

    Hydrolases play a crucial role in the biochemical process, which can catalyze the hydrolysis of various compounds like carboxylic esters, phosphoesters, amides, nucleic acids, peptides, and so on. The design of artificial hydrolases has attracted extensive attention due to their scientific significance and potential applications in the field of gene medicine and molecular biology. Numerous macrocyclic metal complexes have been used as artificial hydrolase in the catalytic hydrolysis of the organic substrate. Aza-crown ether for this comment is a special class of the macrocyclic ligand containing both the nitrogen atoms and oxygen atoms in the ring. The studies showed that the aza-crown complexes exhibited high activity of hydrolytic enzyme. However, the aza-crown ether metal complex as artificial hydrolase is still very limited because of its difficulty in synthesis. This review summarizes the development of the aza-crown ether metal complexes as the artificial hydrolase, including the synthesis and catalysis of the transition metal complexes and lanthanide metal complexes of aza-crown ethers. The purpose of this review is to highlight: (1) the relationship between the structure and hydrolytic activity of synthetic hydrolase; (2) the synergistic effect of metal sites and ligands in the course of organic compound hydrolysis; and (3) the design strategies of the aza-crown ethers as hydrolase. PMID:26460062

  5. Semi-supervised SVM for individual tree crown species classification

    Science.gov (United States)

    Dalponte, Michele; Ene, Liviu Theodor; Marconcini, Mattia; Gobakken, Terje; Næsset, Erik

    2015-12-01

    In this paper a novel semi-supervised SVM classifier is presented, specifically developed for tree species classification at individual tree crown (ITC) level. In ITC tree species classification, all the pixels belonging to an ITC should have the same label. This assumption is used in the learning of the proposed semi-supervised SVM classifier (ITC-S3VM). This method exploits the information contained in the unlabeled ITC samples in order to improve the classification accuracy of a standard SVM. The ITC-S3VM method can be easily implemented using freely available software libraries. The datasets used in this study include hyperspectral imagery and laser scanning data acquired over two boreal forest areas characterized by the presence of three information classes (Pine, Spruce, and Broadleaves). The experimental results quantify the effectiveness of the proposed approach, which provides classification accuracies significantly higher (from 2% to above 27%) than those obtained by the standard supervised SVM and by a state-of-the-art semi-supervised SVM (S3VM). Particularly, by reducing the number of training samples (i.e. from 100% to 25%, and from 100% to 5% for the two datasets, respectively) the proposed method still exhibits results comparable to the ones of a supervised SVM trained with the full available training set. This property of the method makes it particularly suitable for practical forest inventory applications in which collection of in situ information can be very expensive both in terms of cost and time.

  6. Extraction chromatographic studies on a strontium selective crown ether

    International Nuclear Information System (INIS)

    Selective adsorption of radiostrontium from nitric acid medium on a chromatographic resin material consisting of di-t-butyl cyclohexano 18 crown 6/n-octanol sorbed onto amberlite XAD-7 (particle size: 100-150μm) has been carried out. The column capacity is evaluated as ∼ 21 mg of Sr per gram of the resin material. The separation of radiostrontium from several metal ions present in environmental and biological samples viz. Li, Na, K, Mg, Ca, Al, Fe, Co, Ni, Zn and Cd has been achieved. A promising separation method for 90Y from 90Sr-90Y mixture has also been developed. Nitric acid concentration has no observable effect on the elution profile of 90Y as the entire amount of the loaded 90Y activity can be eluted by 1.5 ml of the acid in a wide concentration range (0. 1 - 10 M). Half-life of the eluted 90Y sample is calculated as 63.75 ± 0.40 hours by following the decay profile. Repeated elutions using 1.5 ml of 3 M HNO3 after loading 200 μCi of 90Sr - 90Y revealed that the product with ∼ 98% radiochemical purity could be obtained up to the 12th run beyond which the contamination due to 90Sr increased significantly. (author)

  7. Molar crown inner structural organization in Javanese Homo erectus.

    Science.gov (United States)

    Zanolli, Clément

    2015-01-01

    This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia. PMID:25209431

  8. Crown ethers and phase transfer catalysis in polymer science

    CERN Document Server

    Carraher, Charles

    1984-01-01

    Phase transfer catalysis or interfacial catalysis is a syn­ thetic technique involving transport of an organic or inorganic salt from a solid or aqueous phase into an organic liquid where reaction with an organic-soluble substrate takes place. Over the past 15 years there has been an enormous amount of effort invested in the development of this technique in organic synthe­ sis. Several books and numerous review articles have appeared summarizing applications in which low molecular weight catalysts are employed. These generally include either crown ethers or onium salts of various kinds. While the term phase transfer catalysis is relatively new, the concept of using a phasetrans­ fer agent (PTA) is much older~ Both Schnell and Morgan employed such catalysts in synthesis of polymeric species in the early 1950's. Present developments are really extensions of these early applications. It has only been within the last several years that the use of phase transfer processes have been employed in polymer synthesis...

  9. The Role of the British Crown on Security Issues

    Directory of Open Access Journals (Sweden)

    Behar Selimi

    2016-07-01

    Full Text Available United Kingdom is a limited parliamentary monarchy, in which state sovereignty is exercised jointly by two basic political institutions: Royal Crown and Parliament. The credit for a successful political co-governance of these institutions, which are simultaneously bearers of popular sovereignty, are usually addressed to the Queen's lack of executive power to exercise power alone and hence all the restraint in the race for primate of governance. It goes even further considering that the Queen is quite weak and has only ceremonial functions, which do not disturb the Parliament. However, a careful researcher may notice that the Queen continues to affect the British Government in general and in particular on defence issues. Declassification of communication between Prince Charles and the Government in 2013, pointed out a continuing impact of the Queen and her son on many political issues, including those of defence and security. Since Britain has no codified constitution in a single document, it is not easy to determine the real power and competences of the Queen. It is even more difficult, because customary law and precedent prevail. Therefore, the real definition of the role of the Queen in general in the British Government, can be done by studying the culture, structure and constitutional practice. On their basis I will try to determine the real impact of the Queen in matters of defence and security, whether through her prerogatives in relation to the Government and Parliament, or through moral and informal influence in relation to the Prime Minister and particular ministers.

  10. Investigation of iron(III) complex with crown-porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Pankratov, Denis A., E-mail: pankratov@radio.chem.msu.ru; Dolzhenko, Vladimir D. [Lomonosov Moscow State University (Russian Federation); Stukan, Reonald A. [Semenov Institute of Chemical Physics, Russian Academy of Sciences (Russian Federation); Al Ansari, Yana F.; Savinkina, Elena V. [Lomonosov Moscow State Academy of Fine Chemical Technology (Russian Federation); Kiselev, Yury M. [Lomonosov Moscow State University (Russian Federation)

    2013-08-15

    Iron complex of 5-(4-(((4 Prime -hydroxy-benzo-15-crown-5)-5 Prime -yl)diazo)phenyl)-10,15, 20-triphenylporphyrin was investigated by {sup 57}Fe Moessbauer spectroscopy and EPR. Two Fe sites were identified; they give two differing signals, doublet and wide absorption in a large velocity interval. EPR spectra of solutions of the complex in chloroform at room temperature also show two signals with g = 2.064, A{sub Fe} = 0.032 cm{sup - 1}; g = 2.015, A{sub Fe} = 0.0034 cm{sup - 1}. The doublet asymmetry is studied vs. temperature and normal angle to the sample plane and gamma-beam. The isomer shift {delta} in the doublet varies from 0.25 to 0.41 mm/s in the 360-5 K temperature range, whereas quadruple splitting value is constant, {Delta} {approx} 0.65 mm/s. The relax absorption may be described as a wide singlet ({delta} = 0.30- 0.44 mm/s and {Gamma} = 2.83-3.38 mm/s); its relative area strongly depends on temperature. According to {delta}, both signals are assigned to Fe(III)

  11. Combined crown lengthening surgery with restorative therapy for inducing papilla growth: a case report%牙冠延长术结合修复治疗诱导上前牙龈乳头生长1例

    Institute of Scientific and Technical Information of China (English)

    乐迪; 胡文杰; 张豪

    2013-01-01

    A young lady with unsatisfied restorations of upper anterior teeth and swollen gum wanted to improve aesthetics. Oral examination showed that 12-22 were provisional crowns with normal occlusion, poorly gingival contour and gummy smile. The gingiva was red, light swollen and bleeding on probing. X-ray showed the roots of 11, 21 were short and the alveolar bone absorbed. After the periodontal initial treatment, an ideal location of gingival margin was determined. Then, an esthetic periodontal surgery was performed to recover the biology width and the gingival margin was fitted with the anterior teeth. The temporary restorations were made twice to guide the gingiva growth by changing the shape of the restorations and moving up the contact points of the restorations. The ceramic crowns were completed 3 months after the operation. The gummy smile disappeared and the gingival margin was filled well with the upper anterior ceramic crowns. The 14-month follow-up presented a satisfied effect. Crown lengthening surgery combined restorative therapy could lead papilla to grow well. This process is beneficial for the future treatment plan and clinical esthetic evaluation.

  12. Relationship between crown structure of poplar and poplar canker in different site conditions.%不同立地条件下杨树树冠结构与溃疡病的关系

    Institute of Scientific and Technical Information of China (English)

    黄逢龙; 焦一杰; 张星耀; 樊军锋; 梁军

    2011-01-01

    . The correlation of crown width(W) with soil types and thickness of humus layer respectively was very significantly positive and significantly positive;the correlation of height under branch( Hub ) with thickness of soil layer and humus layer respectively was very significantly positive and significantly positive. Besides, disease state of poplar canker and crown structure were very closely related. Disease index was very significantly, negatively correlated with W,percentage of crown length with height( PLCH ) and CSA, and was significantly, negatively correlated with TLA. The order of positive direct effect of crown structure indices on disease index was LAI, CSR, W,TLA and Dfb, and the order of negative direct effect of crown structure indices on disease index was PLCH,CLD, CSA, Hub and Afb. But from decision coefficient, the order of the significance of crown structure indices to disease index was LAI, CLD, PLCH., W, CSR, TLA, Hub and Dfb. Considering comprehensively the relation of crown structure indices with site condition, crown width should be considered as the major index of crown structure for site control of poplar canker because of the moderate significance of crown width to disease index of poplar canker, the significantly positive correlation of crown width with site condition and the very negative correlation of crown width with disease index of poplar canker. So the measures of the choice of better planting site (loam, thick soil layer and humus layer) or fertilization can be taken to regulate crown width for controlling the disease state of poplar canker under a low level and to keep the ecological balance and the stabilization of economic benefit of poplar forests.

  13. Evaluation of novel Calix-crown-6 based solvent systems for cesium extraction from high level waste

    International Nuclear Information System (INIS)

    Several commercially obtained Calix-crown-6 ligands such as: Calix(4)arene-bis-crown-6 (CC), calix(4)arene-benzo-bis-crown-6 (CBC), Calix(4)arene-naphtho-bis-crown-6 (CNC), and Bis-octyloxy)calix(4)arene-mono-crown-6 (CMC) have been evaluated for their Cs uptake ability. The calix-crown-6 ligands were dissolved in phenyl trifluoromethyl sulphone (PTMS) and 1x10-3 M solutions were used for metal ion extraction from nitric acid feed solutions. The effect of nitric acid solution, Cs carrier concentration were also investigated and ligand variation studies were carried out to suggest an extracted species of the type (CsL+)(NO3-)org. (author)

  14. Crown ethers as synergists in the extraction of trivalent lanthanides by 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5

    International Nuclear Information System (INIS)

    Synergistic extraction of trivalent lanthanides such as Nd, Eu and Tm with mixtures of 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 (HPMTFP) and 18-crown-6 or dibenzo-18-crown-6 or 15-crown-5 or monobenzo-15-crown-5 (CE) in chloroform has been investigated. Lanthanides are found to be extracted as Ln(PMTFP)3 with HPMTFP alone and in the presence of crown ether (CE) as Ln(PMTFP)3 . CE. The equilibrium constants of the above species are found to increase monotonically with decreasing ionic radii of these metal ions. The addition of a crown ether to the metal chelate system not only enhances the extraction efficiency but also improves the selectivities among these trivalent lanthanides. (orig.)

  15. Telomerase activity and telomere length in human hepatocellular carcinoma.

    Science.gov (United States)

    Huang, G T; Lee, H S; Chen, C H; Chiou, L L; Lin, Y W; Lee, C Z; Chen, D S; Sheu, J C

    1998-11-01

    Telomerase activity is activated and telomere length altered in various types of cancers, including hepatocellular carcinoma (HCC). A total of 39 HCC tissues and the corresponding non-tumour livers were analysed and correlated with clinical parameters. Telomere length was determined by terminal restriction fragment assay, and telomerase activity was assayed by telomeric repeat amplification protocol. Telomerase activity was positive in 24 of the 39 tumour tissues (1.15-285.13 total product generated (TPG) units) and in six of the 39 non-tumour liver tissues (1.05-1.73 TPG units). In the 28 cases analysed for telomere length, telomere length was shortened in 11 cases, lengthened in six cases, and unaltered in 11 cases compared with non-tumour tissues. Neither telomere length nor telomerase activity was correlated to any clinical parameters. PMID:10023320

  16. Comparison of Fracture Toughness of All-Ceramic and Metal–Ceramic Cement Retained Implant Crowns: An In Vitro Study

    OpenAIRE

    Rao, S.; Chowdhary, R.

    2014-01-01

    To evaluate the fracture toughness of cement-retained implant-supported metal–ceramic molar crown with that of all-ceramic crowns, fabricated using IPS Empress 2 and yttria-stabilized zirconia copings. An dental implant and abutment was embedded in a clear polymethyl methacrylate model. A wax pattern reproducing the anatomy and dimension of a mandibular molar was made using inlay wax. Copings were made from the manufacturers guidelines for zirconia, metal ceramic and empress crown, in total o...

  17. Agronomical and molecular factors influencing bananas (Musa acuminata, AAA, cv ‘Grande-Naine’) susceptibility to crown rot disease

    OpenAIRE

    Lassois, Ludivine

    2009-01-01

    Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An original approach of the disease is proposed and consists on presenting the fruit quality potential at harvest as a key factor in crown rot development. This potential develops during growth of bananas in the field and depends on a physiological and a parasitical component. The...

  18. Emerging infectious disease or evidence of endemicity? A multi-season study of beak and feather disease virus in wild red-crowned parakeets (Cyanoramphus novaezelandiae).

    Science.gov (United States)

    Jackson, Bethany; Varsani, Arvind; Holyoake, Carly; Jakob-Hoff, Richard; Robertson, Ian; McInnes, Kate; Empson, Raewyn; Gray, Richard; Nakagawa, Kahori; Warren, Kristin

    2015-09-01

    Beak and feather disease virus (BFDV) is a single-stranded DNA virus that is the etiological agent of beak and feather disease in both wild and captive parrots. Given that BFDV is globally recognized as a conservation threat for wild parrots, between 2011-2013, red-crowned parakeets (Cyanoramphus novaezelandiae, n = 229), which are endemic to New Zealand, were captured in mist nets on Tiritiri Matangi Island and Hauturu-o-Toi/Little Barrier Island (LBI), New Zealand, for disease surveillance. Blood and feathers from all birds were tested by PCR for BFDV, and full genomes were recovered and sequenced. A subset of blood samples (n = 96) were tested for antibodies to BFDV by the haemagglutination inhibition (HI) test. A further 238 feather samples were obtained from red-crowned parakeets from three sites in the Wellington region of the North Island, and these were screened for BFDV. The DNA-based prevalence of BFDV infection determined on Tiritiri Matangi Island was 1.09% (CI 95 %, 0.1-3.9%); on Hauturu-o-Toi/LBI, 4.4% (95% CI, 0.5%-15.1%); on Kapiti Island, 3.4% (CI 95%, 1.1-7.8%); at the ZEALANDIA-Karori sanctuary, 1.6% (95% CI, 0-8.4%); and on Matiu-Somes Island, 0% (CI 95%, 0-12.3%). Seroprevalence for BFDV, indicating prior or current exposure, in the Tiritiri Matangi Island population, it was 2% (CI 95%, 0-10.1%), and in the Hauturu-o-Toi/LBI population was 14% (CI 95%, 5.3-27.9%). BFDV-positive birds showed no signs of clinical disease, with the exception of an individual bird obtained opportunistically from Shakespear Regional Park during the study period, which had classical signs of feather loss. Phylogenetic analysis of the 11 full genome sequences recovered from BFDV-positive red-crowned parakeets revealed evidence of ongoing viral flow between red-crowned parakeets and eastern rosellas (Platycercus eximius) in the Hauraki Gulf/Auckland region, with separate but closely related strains from the Wellington region of the North Island. This is the first study

  19. Clergy, nobility and crown in Decadência

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2005-01-01

    Full Text Available In the current work I intend to inquire into the internal motives that led the Portuguese seaborne empire to decadence. After making a brief review of the historiography about the decline of Estado da Índia, I proceed to the analysis of the Crown-Church-Nobility triangle in the course of os Descobrimentos, and of their respective roles in the evolution of Portuguese empire. The absolutization of the crown, the over-expansion of the clergy and the empowerment of the aristocracy became the most conspicuous and longstanding features in the Portuguese social fabric after the country launched herself into maritime undertakings, which crippled her agriculture and retarded the industrialization. As a consequence, the rise of bourgeoisie and the transformation of mercantilist economy into the capitalist were obstructed, and a strong adventurous but non-productive spirit mixed with disdain of manual work prevailed both in metropolis and in overseas territories. In conclusion, the Portuguese decadence commenced from within rather than from without, and far prior to Dutch intrusions in Portuguese Asia, which only accelerated the decline.No presente trabalho tenciono indagar as causas internas que dirigiram o império marítimo português à decadência. Depois de uma revisitação da historiografia relativa ao declínio do Estado da Índia, procedo a uma análise do triângulo de Monarca-Igreja-Nobreza durante os Descobrimentos e dos seus papéis respectivos no evoluir do Império português. É verificável que a absolutização da Coroa, a sobre-expansão do clero e a potenciação da aristocracia tornaram-se as características mais salientes e duradouras na estrutura social portuguesa depois de o país se lançar nas façanhas marítimas, do que resultou a agricultura prejudicada e indústria atrasada. A predominância dessas três instituições, por um lado, impediu a ascensão da burguesia, assim dificultando a transformação da economia

  20. Design of swing device for crown-block heave compensation system%天车升沉补偿系统摇摆装置的设计

    Institute of Scientific and Technical Information of China (English)

    张彦廷; 渠迎锋; 刘振东; 马江涛

    2012-01-01

    为了确定天车升沉补偿系统关键部件摇摆装置的结构参数,基于Simulink软件系统,建立摇摆装置的数学模型,对天车、补偿缸和摇臂装置进行了系统动力学数值模拟,分析了摇摆装置钢丝绳倾角、钢丝绳对天车作用力与天车位移之间的相互关系,以及摇臂装置2个摇臂夹角与补偿缸受力状态的关系.研究表明:摇摆装置的摇臂长度、摇臂下臂固定铰链点位置等结构参数对天车的运动规律、受力状态和补偿性能具有较大影响,天车从最低临界位置向最高临界位置运动的过程中,补偿缸受力随两摇臂夹角的增大先减小后增大.计算得到了摇摆装置各摇臂的长度,确定了摇臂下臂固定铰链点的位置参数和补偿缸固定铰链点的位置参数.%A swing device mathematical model was established by the Simulink software system in order to determine the structure parameters of crown-block heave compensation device' s key components. The crown-block, compensating cylinder and rocker arm device were simulated dynamically. The interrelation between the inclined angle of wire line, the force on the crown-block affected by wire line and the crown-block displacement was analyzed. The relationship between the angle of two rocker arm and the force state of compensating cylinder was also investigated. The study shows that the structure parameters, such as the length of the rocker arm device, the fixed hinge point position of the rocker arm device and so on, have large effects on the crown-block's motion rule, force state and compensating property. The force of compensating cylinder first decreases and then increases along with the angle of two rocker arm increases when the crown-block moves from the lowest position to highest position. The length of the rocker arm device was calculated, and the fixed hinge point position of the rocker arm device and the fixed hinge point position of the compensating cylinder were

  1. Fracture resistance of computer-aided design/computer-aided manufacturing-generated composite resin-based molar crowns

    OpenAIRE

    Harada, A.; Nakamura, Keisuke; Kanno, Taro; Inagaki, R.; Ørtengren, Ulf Thore; Niwano, Y; Sasaki, Keiichi; Egusa, Hiroshi

    2015-01-01

    The aim of this study was to investigate whether different fabrication processes, such as the computer-aided design/computer-aided manufacturing (CAD/CAM) system or the manual build-up technique, affect the fracture resistance of composite resin-based crowns. Lava Ultimate (LU), Estenia C&B (EC&B), and lithium disilicate glass-ceramic IPS e.max press (EMP) were used. Four types of molar crowns were fabricated: CAD/CAM-generated composite resin-based crowns (LU crowns); manua...

  2. Predictive factors of length of inpatient treatment in anorexia nervosa

    OpenAIRE

    Strik Lievers, Luisa; Curt, Florence; Wallier, Jenny; Perdereau, Fabienne; Rein, Zoé; Jeammet, Philippe; Godart, Nathalie

    2008-01-01

    Abstract Objective To identify clinical variables influencing the length of stay (LOS) of inpatient treatment for anorexia nervosa (AN). Method We analyzed structured clinical charts of 300 consecutive hospitalizations for AN in a specialized eating disorder unit. The sample included patients from 12 to 22 years ...

  3. Minimum Length from First Principles

    CERN Document Server

    Calmet, X; Hsu, S D H; Calmet, Xavier; Graesser, Michael; Hsu, Stephen D. H.

    2005-01-01

    We show that no device or gedanken experiment is capable of measuring a distance less than the Planck length. By "measuring a distance less than the Planck length" we mean, technically, resolve the eigenvalues of the position operator to within that accuracy. The only assumptions in our argument are causality, the uncertainty principle from quantum mechanics and a dynamical criteria for gravitational collapse from classical general relativity called the hoop conjecture. The inability of any gedanken experiment to measure a sub-Planckian distance suggests the existence of a minimal length.

  4. Stochastic Mixed-Effects Parameters Bertalanffy Process, with Applications to Tree Crown Width Modeling

    Directory of Open Access Journals (Sweden)

    Petras Rupšys

    2015-01-01

    Full Text Available A stochastic modeling approach based on the Bertalanffy law gained interest due to its ability to produce more accurate results than the deterministic approaches. We examine tree crown width dynamic with the Bertalanffy type stochastic differential equation (SDE and mixed-effects parameters. In this study, we demonstrate how this simple model can be used to calculate predictions of crown width. We propose a parameter estimation method and computational guidelines. The primary goal of the study was to estimate the parameters by considering discrete sampling of the diameter at breast height and crown width and by using maximum likelihood procedure. Performance statistics for the crown width equation include statistical indexes and analysis of residuals. We use data provided by the Lithuanian National Forest Inventory from Scots pine trees to illustrate issues of our modeling technique. Comparison of the predicted crown width values of mixed-effects parameters model with those obtained using fixed-effects parameters model demonstrates the predictive power of the stochastic differential equations model with mixed-effects parameters. All results were implemented in a symbolic algebra system MAPLE.

  5. Stress and Reliability Analysis of a Metal-Ceramic Dental Crown

    Science.gov (United States)

    Anusavice, Kenneth J; Sokolowski, Todd M.; Hojjatie, Barry; Nemeth, Noel N.

    1996-01-01

    Interaction of mechanical and thermal stresses with the flaws and microcracks within the ceramic region of metal-ceramic dental crowns can result in catastrophic or delayed failure of these restorations. The objective of this study was to determine the combined influence of induced functional stresses and pre-existing flaws and microcracks on the time-dependent probability of failure of a metal-ceramic molar crown. A three-dimensional finite element model of a porcelain fused-to-metal (PFM) molar crown was developed using the ANSYS finite element program. The crown consisted of a body porcelain, opaque porcelain, and a metal substrate. The model had a 300 Newton load applied perpendicular to one cusp, a load of 30ON applied at 30 degrees from the perpendicular load case, directed toward the center, and a 600 Newton vertical load. Ceramic specimens were subjected to a biaxial flexure test and the load-to-failure of each specimen was measured. The results of the finite element stress analysis and the flexure tests were incorporated in the NASA developed CARES/LIFE program to determine the Weibull and fatigue parameters and time-dependent fracture reliability of the PFM crown. CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/Or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program.

  6. Aesthetic comparison between crowns made with Cubo and metal-ceramic systems

    Directory of Open Access Journals (Sweden)

    Lis Regina Carneiro HOPPEN

    2010-06-01

    Full Text Available Introduction and objective: The objective of this study was to verify the influence of different materials used in the construction of infrastructures on the aesthetic result of restorations with ceramic coating. Material and methods: A patient that needed a single prosthetic crown on the maxillary central incisors was selected for treatment, one in the right maxillary central incisor (11 and another in the dental implant (21.Metal-free (Cubo system and metal-ceramic (MC crowns were made for each tooth and submitted to blind review by 11 dentists, who answered a questionnaire about ratios of opacity and translucency of the crowns in the oral cavity of the patient, where each answer corresponded to one score.Data was submitted to Wilcoxon test (α = 0.05. Results: Therewas no significant statistical difference between the metal-ceramic and Cubo system crowns (11: p = 0.107; 21: p = 0.739. The analysis of the scores also showed that for the same type of infrastructure there was no significant statistical difference between 11 and 21 (Cubo: p = 0.206; MC: p = 0.102. Conclusion: Within the limits of this study, it was concluded that, according to the visual perception of the evaluators,prosthetic crowns made with metal infrastructure and with ceramic infrastructure showed to be aesthetically similar and satisfactory.

  7. Microseismicity Induced by Fault Activation During the Fracture Process of a Crown Pillar

    Science.gov (United States)

    Zhang, Penghai; Yang, Tianhong; Yu, Qinglei; Xu, Tao; Zhu, Wancheng; Liu, Honglei; Zhou, Jingren; Zhao, Yongchuan

    2015-07-01

    Shirengou iron mine in Hebei Province, China is now under transition from open pit to underground mining. During this process, the unstable failure risk of crown pillar is growing as a result of underground mining, fault activation and water seepage. To monitor the stability of the crown pillar, a microseismic monitoring system was equipped in 2006. Based on temporal and spatial distribution of microseismic events and deformation mechanism, it was found that it is the propagation of the buried fault F15 that causes the failure of the crown pillar, resulting in increased water seeping into the underground drifts. By analyzing the temporal changes in multiple microseismic parameters during the fracture process of the crown pillar, it was found that several distinct abnormalities in the microseismic data such as a rapid decrease in the b value, a sharp increase in energy release, an abnormal increase in apparent stress and a low dominant frequency, could be judged as the signal of an increasing risk. Therefore, the microseismic monitoring has been proven to be a suitable method for understanding damage and fracture process of the crown pillar during the transition from open pit to underground mining.

  8. Involvement of phenolic compounds in the susceptibility of bananas to crown rot. A review

    Directory of Open Access Journals (Sweden)

    Lassois, L.

    2012-01-01

    Full Text Available Crown rot of bananas, caused by a fungal parasitic complex, is one of the main quality defects of exported bananas. Major variations in the susceptibility of bananas to crown rot have been observed in different production zones. The physiological state of the banana fruit at harvest is said to influence its response to pathogenic attack and thus to modulate its susceptibility to crown rot. The susceptibility of bananas to this disease, however, appears to be influenced by many pre-harvest factors, although the underlying defense mechanisms have not been clearly identified. A recent report based on molecular analyses suggests that phenolic compounds might be involved in the different variations in the susceptibility of bananas to crown rot. Results of other earlier studies point to an involvement of phenolic compounds in the defensive reactions of banana plants against various pathogens. The present paper reviews the current state of knowledge on the variations in the susceptibility of bananas to crown rot and takes stock of what is known about phenolic compounds in relation to their potential involvement in the defense mechanisms of the banana plant.

  9. Effects of Computer-Aided Manufacturing Technology on Precision of Clinical Metal-Free Restorations

    Directory of Open Access Journals (Sweden)

    Ki-Hong Lee

    2015-01-01

    Full Text Available Purpose. The purpose of this study was to investigate the marginal fit of metal-free crowns made by three different computer-aided design/computer-aided manufacturing (CAD/CAM systems. Materials and Methods. The maxillary left first premolar of a dentiform was prepared for all-ceramic crown restoration. Thirty all-ceramic premolar crowns were made, ten each manufactured by the Lava system, Cercon, and Cerec. Ten metal ceramic gold (MCG crowns served as control. The marginal gap of each sample was measured under a stereoscopic microscope at 75x magnification after cementation. One-way ANOVA and the Duncan’s post hoc test were used for data analysis at the significance level of 0.05. Results. The mean (standard deviation marginal gaps were 70.5 (34.4 μm for the MCG crowns, 87.2 (22.8 μm for Lava, 58.5 (17.6 μm for Cercon, and 72.3 (30.8 μm for Cerec. There were no significant differences in the marginal fit among the groups except that the Cercon crowns had significantly smaller marginal gaps than the Lava crowns (P<0.001.  Conclusions. Within the limitation of this study, all the metal-free restorations made by the digital CAD/CAM systems had clinically acceptable marginal accuracy.

  10. Definition of Magnetic Exchange Length

    Energy Technology Data Exchange (ETDEWEB)

    Abo, GS; Hong, YK; Park, J; Lee, J; Lee, W; Choi, BC

    2013-08-01

    The magnetostatic exchange length is an important parameter in magnetics as it measures the relative strength of exchange and self-magnetostatic energies. Its use can be found in areas of magnetics including micromagnetics, soft and hard magnetic materials, and information storage. The exchange length is of primary importance because it governs the width of the transition between magnetic domains. Unfortunately, there is some confusion in the literature between the magnetostatic exchange length and a similar distance concerning magnetization reversal mechanisms in particles known as the characteristic length. This confusion is aggravated by the common usage of two different systems of units, SI and cgs. This paper attempts to clarify the situation and recommends equations in both systems of units.

  11. A comparison of inlay crown with three different retention forms on the short coronal molars%三种不同固位形式嵌体冠修复短冠磨牙的应用比较

    Institute of Scientific and Technical Information of China (English)

    肖云鹤; 计华; 余俐; 刘洋; 余美芳; 王行

    2016-01-01

    目的:采用不同固位形式嵌体冠对短冠磨牙进行修复,对比观察疗效,评估其临床修复效果。方法:选取66颗根管治疗后的短冠磨牙进行钴铬合金嵌体冠修复,分为髓室固位嵌体冠组、常规桩核嵌体冠组、插销桩核嵌体冠组。所有患者修复2年后,对修复体粘结效果进行评价。结果:髓室固位嵌体冠粘结强度小于常规桩核嵌体冠和插销桩核嵌体冠,但3组之间无明显差异。结论:3种固位方式嵌体冠的粘结强度均能满足临床修复的要求,临床上应视基牙情况选择适合的修复方式。%Objective:To evaluate the restoration effect of inlay crown with three retention forms on the recently extracted molars. Method:66 short coronal molars with Cobalt chromium alloy were divided into three groups after root canal therapy using pulp chamber retention inlay crown, conventional post-and-core inlay crown, insertion-type separate inlay crown respectively. The bonding effect were evaluated after 2 years’ clinical restoration. Result: The bonding strength of pulp chamber retention inlay crown was less than other retention forms, but there was no obvious difference among three groups. Conclusion:The bonding strength of inlay-crowns that all of the three kinds of retention forms could meet the clinical requirements for restoration. The appropriate restoration methods can be selected according to specific condition of abutment teeth in clinical practice.

  12. Minimum Length from First Principles

    OpenAIRE

    Calmet, Xavier; Graesser, Michael; Hsu, Stephen D. H.

    2005-01-01

    We show that no device or gedanken experiment is capable of measuring a distance less than the Planck length. By "measuring a distance less than the Planck length" we mean, technically, resolve the eigenvalues of the position operator to within that accuracy. The only assumptions in our argument are causality, the uncertainty principle from quantum mechanics and a dynamical criteria for gravitational collapse from classical general relativity called the hoop conjecture. The inability of any g...

  13. Multi-fiber posts restore molar residual root and crown%多个玻璃纤维桩树脂核修复磨牙残冠

    Institute of Scientific and Technical Information of China (English)

    刘新庆; 刘怡珍; 刘淑琴

    2011-01-01

    背景:由于铸造金属桩核弹性模量大,修复磨牙残冠残根时易造成根尖部根折,难以取出、生物相容性差等缺点.目的:评价多个玻璃纤维桩修复磨牙残冠的临床效果.方法:选择26例31颗磨牙残冠,经完善根管治疗后,选择两至三个根管制作玻璃纤维桩树脂核,然后进行氧化锆全瓷冠修复,随访观察治疗效果.结果与结论:随访12~24个月,3颗全瓷冠出现颜色偏差,因后牙对美观影响不大,患者未提出异议;1颗冠崩瓷而重做外冠,1颗冠因邻接关系不良导致食物嵌塞而重做外冠,1颗冠因牙合龈距离低,聚合度过大冠脱落,经增加辅助固位型后重做外冠,重做外冠观察半年以上未见异常.其余病例修复体外形良好,边缘密合,X射线检查桩与根管密贴,无桩或根折,根尖根周牙槽骨无吸收影像.表明多纤维桩树脂核技术修复磨牙残冠能够获得良好的近期临床效果.%BACKGROUND: Cast metal posts with big elastic modulus and poor biocompatibility can result in apical root fractures that aredifficult to remove during residual molar crown repairment.OBJECTIVE: To evaluate the therapeutic effects of multi -fiber posts on the restoration of the molar residual root and crown.METHODS: A total of 26 patients with 31 molars were included. A fter satisfactory root canal therapy, the teeth were repairedusing two or three glass fiber posts and zirconia-ceramic crowns.RESULTS AND CONCLUSION: During 12-24 months of clinical follow-up, one had food impaction for bad adjacency, one hadabscission of all-ceramic crown, one had porcelain collapse caused by hard food biting. No loosening, fracture and gap existedamong fiber post, composite resin core, dentine and crown. No dislodgment or fracture of posts or roots was observed inrestorations. Multi -fiber post and cores and all-ceramic crown are reliable and ideal materials in the restorations of molar residualroot and crown.

  14. Phytophthora Root and Crown Rot on Apples in Bulgaria

    Directory of Open Access Journals (Sweden)

    Mariana Nakova

    2010-01-01

    Full Text Available Phytophthora is a genus of Oomycota responsible for some of the most serious diseases with great economic impact (Judelson and Blanco, 2005. While 54 species were found in the 20th century (Erwin and Ribeiro, 1996 another 51-54 new species have been identified(Brasier, 2008 since the year 2000. They are spread worldwide and have broad range of host plants – fruit trees, citrus, forest and park species. Phytophthora can cause serious damages in orchards and nurseries of apples, cherries, etc. In Bulgaria they have been found first on young apples and cherries (1998-1999 in Plovdiv region (Nakova, 2003. Surveys have been done for discovering disease symptoms in Plovdiv and Kjustendil regions. Isolates have been obtained from infected plant material (roots and stem bases applying baiting bioassay (green apples, variety Granny Smith and/or PARP 10 selective media. Phytophthora strains were identified based on standard morphology methods – types of colonies on PDA, CMA, V 8, type and size of sporangia, oogonia and antheridia, andoospores. Cardial temperatures for their growth were tested on CMA and PDA.For molecular studies, DNA was extracted from mycelium using the DNA extraction kit.DNA was amplified using universal primers ITS 6 and ITS 4. Amplification products concentrations were estimated by comparison with the standard DNA. Sequencing was done at the Scottish Crop Research Institute (SCRI, Dundee, Scotland. Phytophthora root and crown rot symptoms first appear in early spring. Infected trees show bud break delay, have small chlorotic leaves, and branches die all of a sudden. Later symptoms are found in August-September. Leaves of the infected trees show reddish discoloration and drop down. Both symptoms are connected with lesions (wet, necrotic in appearance at stem bases of the trees.Disease spread was 2-3% in most gardens, only in an apple orchard in Bjaga (Plovdiv region it was up to 8-10%. Morphologically, the isolates acquired from

  15. Metal chelation and spatial profiling of components in crown ether functionalised conducting copolymer films

    International Nuclear Information System (INIS)

    Crown ether functionalised conducting polymer films were used to complex barium ions from acetonitrile solution. It was found that fully-functionalised N-derivatized polypyrrole films do not possess adequate mechanical stability, but dilution with unfunctionalised bithiophene co-monomer leads to a series of copolymer films with excellent stability. Film reactivity, composition and structure were investigated using electrochemical, nanogravimetric, FTIR, XPS and neutron reflectivity techniques. The first three of these provided spatially integrated barium populations and neutron reflectivity provided spatially resolved compositional profiles. Measurements at various stages of film fabrication yielded spatial distributions of co-monomer, crown ether, solvent and barium (as perchlorate) components. Critically, the amount of free volume to accommodate crown motifs and barium within the film was limited by the film's internal microstructure and solvent content; the low solvent volume fraction creates a different local environment to solution.

  16. Rational Design of Cesium-Selective Ionophores and Chemosensors: Dihydrocalix[4]arene Crown-6 Ethers

    Energy Technology Data Exchange (ETDEWEB)

    Sachleben, Richard A.; Bryan, Jeffrey C.; Brown, Gilbert M.; Engle, Nancy L.; Haverlock, Tamara J.; Hay, Benjamin P.; Urvoas, Agathe; Moyer, Bruce A.

    2003-12-15

    Molecular mechanics calculations performed on calix[4]arene crown-6 ethers predict that the 1,3-dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3-dialkoxy calix crowns. The X-ray crystal structures of 1,3-alt bis-octyloxycalix[4]arene benzocrown-6 ether, dihydrocalix[4]arene benzocrown-6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown-6 ether were determined. The cesium complex structure corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown-6 ethers exhibit enhanced cesium selectivity in the extraction of alkali metal salts and provide a platform for a highly sensitive and selective cesium chemosensor.

  17. Zirconia- versus metal-based, implant-supported abutments and crowns

    DEFF Research Database (Denmark)

    Hosseini, Mandana

    selection of restoration materials should be based on proper optical characteristics in addition to biocompatibility and sufficient strength of materials. Abutments and crowns based on zirconia are one of the most recent alternatives to metal abutments and metal-ceramic crowns. To date, only few comparative...... estimate long-term biomechanical results of zirconia-based versus metal-based restorations. The aim of study I was to analyse the mode of fracture and number of cyclic loadings until veneering fracture of zirconia-based all-ceramic restorations compared to metal-ceramic restorations. The aim of study II...... was to test the reliability and validity of six aesthetic parameters used at the Copenhagen Dental School to assess the aesthetic outcome of implant-supported restorations. The aims of study III and IV were to compare the influence of different abutment and crown materials on biological, biomechanical...

  18. [Establishment of database with standard 3D tooth crowns based on 3DS MAX].

    Science.gov (United States)

    Cheng, Xiaosheng; An, Tao; Liao, Wenhe; Dai, Ning; Yu, Qing; Lu, Peijun

    2009-08-01

    The database with standard 3D tooth crowns has laid the groundwork for dental CAD/CAM system. In this paper, we design the standard tooth crowns in 3DS MAX 9.0 and create a database with these models successfully. Firstly, some key lines are collected from standard tooth pictures. Then we use 3DS MAX 9.0 to design the digital tooth model based on these lines. During the design process, it is important to refer to the standard plaster tooth model. After some tests, the standard tooth models designed with this method are accurate and adaptable; furthermore, it is very easy to perform some operations on the models such as deforming and translating. This method provides a new idea to build the database with standard 3D tooth crowns and a basis for dental CAD/CAM system. PMID:19813628

  19. Luminescence of divalent europium complexes with crown ethers, cryptands and polyethylene glycols

    International Nuclear Information System (INIS)

    The luminescence properties of the divalent europium complexes with crown ethers, cryptands and polyethylene glycols were studied. The observed intensity of luminescence is generally reported. The most intense luminescence is produced by a methanolic solution of the 15-crown-5 complex with europium(II), the intensity of which is 600 times greater than that of a solution of EuCl2 in methanol with the same europium(II) concentration. The enhancement of the emission intensity as a result of the formation of complexes with crown ethers can be attributed to ''insulation'' of the europium(II) ion from close approach of the solvent molecules which would produce radiationless energy losses. (Auth.)

  20. Sexual dimorphism in crown units of mandibular deciduous and permanent molars in Australian Aborigines.

    Science.gov (United States)

    Kondo, S; Townsend, G C

    2004-01-01

    Sexual differences in the crown units of mandibular molars were investigated in Australian Aborigines. The first and second deciduous molars (dm1 and dm2), and first to third permanent molars (M1, M2 and M3) were measured on dental casts using a sliding caliper. Measurements of tooth crowns included overall mesiodistal and buccolingual diameters, as well as the mesiodistal and buccolingual diameters of the trigonid and talonid. Percentage dimorphism values were greater in the talonid dimensions than the trigonid, indicating that sex differences tend to be larger in the later-developing crown units. Sex differences in mesiodistal diameters increased from dm1 to M2 but decreased for M3, the tooth that showed the least dimorphism of all the molars. This result seems to be due to the marked variability in size of the M3 between individuals. PMID:15553268

  1. [Changes of reproduction habitat quality of red-crowned crane in Zhalong wetlands].

    Science.gov (United States)

    Wang, Zhi-qiang; Fu, Jian-chun; Quan, Bin; Zhang, Dong-shui; Wang, Fang

    2010-11-01

    Based on the maps of habitat factors in Zhalong wetlands in 1996 and 2004, two models called habitat suitability index model and nearest neighbor analysis model were established to quantitatively analyze the changes of reproduction habitat quality of red-crowned crane in Zhalong wetlands. The results showed that in 1996-2004, the suitable reproduction habitats of red-crowned crane in the wetlands experienced both area loss and functional loss. By the end of 2004, the suitable habitats in the study area lost greatly, and those in core area undergone serious fragmentation. Consequently, the habitat-selection behaviors of red-crowned crane responded in two ways: one was the centralization of nests towards core area, and the other was the spatial distribution pattern changed from uniform to aggregative. PMID:21361012

  2. A study on zinc isotope fractionation in a benzo crown resin/acetone system

    International Nuclear Information System (INIS)

    Zinc isotope fractionation has been studied in different cavities of crown ether resins that were synthesized in porous silica beads. Displacement chromatography was performed, as a breakthrough manner, in glass columns by feeding in a zinc chloride solution. From the mass analysis of effluents, the heavier isotopes of zinc were enriched at the beginning of the zinc adsorption band. The front maximum enrichment (1.0168), separation coefficient (8.1 x 10-4), and smaller HETP (0.205 cm) for the isotopic pair 68Zn/64Zn were obtained with the use of the benzo-15-crown-5 resin. Zinc isotope fractionation was obviously affected by the cavity size of the crown ethers. (author)

  3. Crowned spiropyran fluoroionophores with a carboxyl moiety for the selective detection of lithium ions.

    Science.gov (United States)

    Stubing, D B; Heng, S; Abell, A D

    2016-04-12

    The absorbance and fluorescence spectra of carboxylated spiropyrans containing methyl-1-aza-12-crown-4, methyl-1-aza-15-crown-5, methyl-1-aza-18-crown-6 moieties are compared. Characteristic changes in spectra after addition of the alkali metal salts of Li(+), Na(+), K(+) and Cs(+) were observed. Chromism induced by the binding of the metal cations was observed as an increase in absorbance and fluorescence. Of these metal cations, the Li(+) ion produced the largest change in all three spiropyran systems. Reversible photoswitching of the spiropyran-metal complexes was observed on irradiation with alternating 352 nm UV and white light. This results in reversible fluorescence based sensing of lithium ions with potential for use in a biological sensor device. PMID:27001932

  4. Elastic-plastic behaviour of a nuclear pipe elbow with axial through wall crack at crown under in-plane bending

    International Nuclear Information System (INIS)

    16' pipe elbows are used in the primary heat transport (PHT) system of Indian Pressurised Heavy water Reactors (PHWRs). Cracking at crown of elbows under bending is an important consideration in design. The structural integrity assessment of elbow requires knowledge of fracture parameters like Stress intensity factor, J-integral, crack mouth opening displacement etc. In earlier experimental studies, a full scale 16-inch carbon steel (SA 333 Gr. 6) elbow used in the PHT system, was subjected to fatigue loading. As a consequence, the elbow had a through wall axial crack at crown having a length of 104 mm. In the present study, the behaviour of this axially cracked 90-degree, long radius nuclear pipe elbow under in-plane closing moment was studied using 3D non-linear finite element analysis with WARP3D software. Limit load, load line displacement, crack mouth opening displacement and J-integral were evaluated for this elbow. The FE model consists of elbow with extended straight pipes and the geometry and thickness are exactly same as that used in the experiment (measured). The comparison of predicted FE results with experimental values were found to be good. This paper presents the details of the FE study and the results obtained, along with the comparisons. (authors)

  5. Segmenting tree crowns from terrestrial and mobile LiDAR data by exploring ecological theories

    Science.gov (United States)

    Tao, Shengli; Wu, Fangfang; Guo, Qinghua; Wang, Yongcai; Li, Wenkai; Xue, Baolin; Hu, Xueyang; Li, Peng; Tian, Di; Li, Chao; Yao, Hui; Li, Yumei; Xu, Guangcai; Fang, Jingyun

    2015-12-01

    The rapid development of light detection and ranging (LiDAR) techniques is advancing ecological and forest research. During the last decade, numerous single tree segmentation techniques have been developed using airborne LiDAR data. However, accurate crown segmentation using terrestrial or mobile LiDAR data, which is an essential prerequisite for extracting branch level forest characteristics, is still challenging mainly because of the difficulties posed by tree crown intersection and irregular crown shape. In the current work, we developed a comparative shortest-path algorithm (CSP) for segmenting tree crowns scanned using terrestrial (T)-LiDAR and mobile LiDAR. The algorithm consists of two steps, namely trunk detection and subsequent crown segmentation, with the latter inspired by the well-proved metabolic ecology theory and the ecological fact that vascular plants tend to minimize the transferring distance to the root. We tested the algorithm on mobile-LiDAR-scanned roadside trees and T-LiDAR-scanned broadleaved and coniferous forests in China. Point-level quantitative assessments of the segmentation results showed that for mobile-LiDAR-scanned roadside trees, all the points were classified to their corresponding trees correctly, and for T-LiDAR-scanned broadleaved and coniferous forests, kappa coefficients ranging from 0.83 to 0.93 were obtained. We believe that our algorithm will make a contribution to solving the problem of crown segmentation in T-LiDAR scanned-forests, and might be of interest to researchers in LiDAR data processing and to forest ecologists. In addition, our research highlights the advantages of using ecological theories as guidelines for processing LiDAR data.

  6. Individual Species Crown Mapping in Taman Rimba Ilmu, University Malaya Using Airborne Hyperspectral Imaging

    Directory of Open Access Journals (Sweden)

    Kamaruzaman Jusoff

    2010-01-01

    Full Text Available Problem statement: Accurate, current and cost-effective individual standing tree data are required by forest management communities for use in forest inventory over large areas. Currently, most of the forest mapping process is done directly on the ground using many technique such as the bearing-distance and also the other technique that use the computer software as a support, such as Tree MapperTM. Instead of ground data collection and where there are difficulties in reaching the individual trees, hyper spectral remote sensing technology is the best option to map the tree positions. Approach: A novel approach to generating an individual tree crown mapping estimated for a lowland dipterocarp forest of Taman Rimba Ilmu, University Malaya, Kuala Lumpur using an airborne hyperspatial (1 m2 ground resolution imager was presented. Results: A total of 297 individual tree crowns comprising of 83 Xylopia sp., 79 Ixonanthes sp., 56 Hevea sp., 15 Streblus elongates, 14 Pellacalyx sp., 12 Endospermum diadenum, 11 Macaranga gigantea, 10 Cratoxylum sp., 10 Cannarium sp. and 7 Ixonanthes icosandra were identified and delineated as individual polygons in a study area plot of 2 ha. Conclusion/Recommendations: It was found out that individual tree crowns in University Malaya can be detected and counted with reasonable field measured to image derived mapping accuracy of 98.65%. This study implied that acceptable individual tree crown classification maps and algometric equations relating diameter at breast height (dbh or crown area to biomass can be used to generate timber volume estimates with established crown-diameter-volume correlations.

  7. Selection and application of oral all-ceramic crown materials%口腔全瓷冠修复材料的选择及应用

    Institute of Scientific and Technical Information of China (English)

    程谨春

    2011-01-01

    BACKGROUND: Compared with porcelain fused to metal crown, the all-ceramic crown materials have been more and more applied in clinical anterior teeth restoration due to natural and stable color, low thermal conductivity, non-electric conductivity, wear resistance, good biocompatibility, non-transparent metallic, and relatively simple operations.OBJECTIVE: To summarize the characteristics, production methods and clinical application of different all-ceramic crown materials.METHODS: A computer-based online retrieval was performed in Wanfang database and Medline database between 2001 and 2011 for articles regarding the characteristics, production methods, physical and mechanical strength, chemical and biological compatibility, aesthetic appearance and clinical application of different all-ceramic crown materials.RESULTS AND CONCLUSION: Currently, the clinically used all-ceramic materials can be divided into slip casting porcelain,casting ceramic, heat-pressed glass ceramic, glass-infiltrated ceramics, densely-sintered aluminum oxide polycrystalline, partially stabilized tetragonal zirconium oxide polycrystalline, and nano-composite ceramic. Different materials have its specific mechanical properties and clinical indications, so clinical selection must be based on specific conditions. With the advance of high-strength ceramic studies, all-ceramic restorations become widely applied, and high-aluminum ceramic represented by In-ceram and zirconia all-ceramic crowns can achieve good effects within a short and long term, foreign clinical experiments have conducted the enlargement from anterior crown to rear crown and bridge. To insure optimum long-term clinical results of all-ceramic crown restorations, the key is to overcome the fragmentation of dental prosthesis, mainly through modifying the composition, improving the anti -smash property of ceramic materials, and a series of prevention measures.%背景:相对于金属烤瓷冠而言,全瓷冠具有色泽稳定自然,导

  8. Study on toxicity mutation of crown-vetch induced by radiation

    International Nuclear Information System (INIS)

    The suckers of Germany crown-vetch were irradiated by 60Co gamma ray and fast neutron. The toxicity mutation frequency and genetic stability of crown-vetch were studied. The various toxicity mutants were found in M1. Most of the toxicity mutants was unstable in M2, Stable mutant was very few (about 2.0-12.9%). β-nitropropionic acid in the low toxicity mutants selected was 31.7-39.8 mg/g. Genetic characteristics of low toxicity mutants were stable in M3-M5

  9. Dicyclohexano-18-crown-6 as a novel carrier in the liquid membrane permeation of actinides

    International Nuclear Information System (INIS)

    The proven extractability and profound selectivity of dicyclohexano-18-crown-6 (DC18C6) has been exploited by selecting this crown ether as the ionophore in liquid membrane transport. Macrocycle-facilitated transport of Pu(IV) and U(VI) against their concentration gradient from aqueous nitric acid solutions across organic bulk liquid membrane (BLM) and thin-sheet supported liquid membrane (SLM) containing DC18C6 as the mobile carrier and toluene as the membrane solvent was investigated. (author). 23 refs., 9 tabs., 7 figs

  10. Simulation of impact assesment of crown forest fires on boudary layer of atmosphere using software PHOENICS

    Science.gov (United States)

    Soprunenko, Elina E.; Perminov, Valeriy; Reyno, Vladimir V.; Loboda, Egor L.

    2015-11-01

    Mathematical model of heat and mass transfer of crown forest fire is used in this paper, which is developed on the base of experimental research data and laws and methods of mechanics of reacting media. The numerical calculation carried out using software PHOENICS for non stationary three dimensional case. K-Ɛ model of turbulence is taken into account. It is studied the influence of temperature and wind velocity in boundary layer of atmosphere on the turbulent kinematic viscosity coefficient value and distribution of temperature above the crown forest fire front.

  11. The electronic structure of the complexes of lanthanide ions with crown ethers

    International Nuclear Information System (INIS)

    The total energies of molecules, electronic structures, charge distribution and Mulliken's bond order in the complexes of lanthanide nitrates (or chlorides) with crown ethers have been calculated by using INDO method. The results have shown that the charge transfer L→Ln at coordination processes leads to the shift of the energy levels and weakening of the bond of Ln-O(NO/sub 3/) or Ln-Cl, and the molecular configuration with the lanthanide ions being coordinated to the ethereal oxygen atoms and the three bidentate nitrate ions (or chloride ions) on one side of the crown ring, is energetically the most preferable one

  12. Column chromatographic separation of Y3+ from Sr2+ by polymeric ionizable crown ether resins

    International Nuclear Information System (INIS)

    Condensation polymers containing subunits of crown ether carboxylic acid monomers are effective stationary phases for the chromatographic separation of Y3+ and Sr2+. The pH range and metal loading capacities for the resins have been determined under equilibrium conditions. The resin can be regenerated for repeated use without losing its separation capability. Altering the molecular structure of the monomer (sym-dibenzo-16-crown-5-oxyacetic acid) by an alkyl substitution on the macrocyclic cavity decreases the loading capacity of the resin

  13. Laser Spectroscopic Study of Cold Host-Guest Complexes of Crown Ethers in the Gas Phase

    OpenAIRE

    Inokuchi, Yoshiya; Kusaka, Ryoji; Ebata, Takayuki; Boyarkin, Oleg V.; Thomas R. Rizzo,

    2012-01-01

    Laser spectroscopic study on the structure and dynamics of cold host-guest inclusion complexes of crown ethers (CEs) with various neutral and ionic species in the gas phase is presented. The complexes with neutral guest species are formed by using supersonic free jets, and those with ionic species are generated with an electrospray ionization (ESI) combined with a cold 22-pole ion trap. For CEs, various sizes of 3n-crown-n-ethers (n = 4, 5, 6 and 8) and their benzene-substituted species are u...

  14. Diaquabromidocopper(II–18-crown-6–water (1/1/2

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2010-07-01

    Full Text Available In the title compound, [CuBr2(H2O2]·C12H24O6·2H2O, the CuII atom, which is situated on an inversion centre and has a slightly distorted square-planar geometry, and the two coordinated water molecules are linked to the 18-crown-6 macrocycles by O—H...O hydrogen bonds. The water molecule of crystallization further links the metal complex and the crown ether macrocycles into a chain along the c axis.

  15. The susceptibility of bananas to crown rot disease is influenced by geographical and seasonal effects

    OpenAIRE

    Ewane, Cécile Annie; Lassois, Ludivine; Lepoivre, Philippe; Brostaux, Yves; de Lapeyre de Bellaire, Luc

    2013-01-01

    Crown rot of banana fruits is caused by a complex of fungal pathogens, the most common of which is Colletotrichum musae, and is one of the main quality defects of exported bananas. Susceptibility of banana fruits to crown rot is influenced by many pre-harvest factors. The aim of this study was to improve on the methodology for the evaluation of fruit susceptibility and to verify whether cultivation areas in Cameroon as well as seasonal variations have an influence on the susceptibility to cro...

  16. Microleakage of Different Self-Adhesive Materials for Lithium Disilicate CAD/CAM Crowns

    OpenAIRE

    Naumova, Ella A.; Alexander Valta; Katharina Schaper; Arnold, Wolfgang H.; Andree Piwowarczyk

    2015-01-01

    Objectives: To evaluate the microleakage and marginal gap of various luting materials after cementing ceramic crowns. Methods: Cervical margins of human molars were designed as circular chamfers. Cementation of full-contour ceramic crowns was conducted with zinc-phosphate cement (Harvard cement), resin cement (Panavia F 2.0) and self-adhesive resin cements (RelyX Unicem, BifixSE, MaxCem Elite, PermaCem2.0, G-Cem). Aging of specimens was performed in artificial saliva, at 37 °C for four weeks...

  17. Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

    Institute of Scientific and Technical Information of China (English)

    LI ZhengYi; TENG MingYu; MA JieJie; HUANG Ji; WANG LeYong; PAN Yi

    2009-01-01

    Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols, and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O-H…п interaction, which has been confirmed by X-ray crystal structures and ESI-MS.

  18. Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols,and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O-H...π interaction,which has been confirmed by X-ray crystal structures and ESI-MS.

  19. Personal Factors Determining Patient Satisfaction with All-Ceramic Crown Treatment for Single Anterior Teeth.

    Science.gov (United States)

    Zou, Yun; Zhan, DeSong

    2016-01-01

    The Eysenck Personality Questionnaire's (EPQ) N value (neuroticism) was used to evaluate information from 158 patients before ceramic crown treatment. Patient satisfaction was also evaluated using a satisfaction questionnaire 2 weeks post treatment. Patient expectations were not correlated with sex, age, or N value, and sex was not correlated with patient satisfaction other than in relation to crown shape. Total esthetic satisfaction and feature improvement were positively correlated with age, while satisfaction for five specific criteria was negatively correlated with N value and overall expectation. These observations underscore the importance of considering the physical and psychologic aspects of patient care when planning dental treatment. PMID:27611752

  20. When the dragon wore the crown putting starlight back into myth

    CERN Document Server

    Cerow, Don

    2013-01-01

    When our ancestors gazed upon the skies thousands of years ago they looked up into the center of Creation and saw a mighty Dragon, a great celestial serpent with wings circling ceaselessly above them, night after night, century after century. When the Dragon Wore the Crown is a ground breaking book that covers a period of over six thousand years, focusing on what astrologers would call the Ages of Gemini, Taurus and Aries and taking us through the period of classical astronomy with the Greeks and Romans (approx. 7000 BC-200 AD).When the Dragon Wore the Crown opens and closes with the Chinese m

  1. The recovery of gold and pyrite from a residue dump at Crown Mines

    International Nuclear Information System (INIS)

    The application of ore-dressing methods to a residue dump at Crown Mines has been examined. The use of either single-stage or double-stage gravity concentration is advocated for the recovery of the gold. Flotation and wet high-intensity magnetic separation (WHIMS) are not recommended. The two-stage gravity process facilitates the recovery of most of the pyrite in the residue (over 70 per cent) at commercial grade (40 per cent sulphur), but sacrifices some of the gold obtainable by a single-stage operation. There is little prospect of the commercial recovery of uranium from the dump at Crown Mines

  2. Proposal of an innovative benchmark for accuracy evaluation of dental crown manufacturing.

    Science.gov (United States)

    Atzeni, Eleonora; Iuliano, Luca; Minetola, Paolo; Salmi, Alessandro

    2012-05-01

    An innovative benchmark representing a dental arch with classic features corresponding to different kinds of prepared teeth is proposed. Dental anatomy and general rules for tooth preparation are taken into account. This benchmark includes tooth orientation and provides oblique surfaces similar to those of real prepared teeth. The benchmark is produced by additive manufacturing (AM) and subjected to digitization by a dental three-dimensional scanner. The evaluation procedure proves that the scan data can be used as reference model for crown restorations design. Therefore this benchmark is at the basis for comparative studies about different CAD/CAM and AM techniques for dental crowns. PMID:22364825

  3. Crown morphology and variation of the lower premolars of Zhoukoudian Homo erectus

    Institute of Scientific and Technical Information of China (English)

    XING Song; ZHOU Mi; LIU Wu

    2009-01-01

    Traditional descriptive observation and advanced geometric morphometric are employed to study the morphological characteristics of Zhoukoudian mandibular premolars,and simultaneously with the specimens of Australopithecus,African early Homo,Homo erectus in other areas of Asia except Zhoukoudian,Europe Pleistocene fossil hominins,and recent Chinese (72 P_3 and 69 P_4 on the whole) being included as comparisons.Results suggest obvious evolutionary changes in the occlusal morphology and crown outline shape of mandibular premolars.Australopithecus P_3s are found with extremely asymmetrical crown outlines,prominent mesial and distal vertical grooves on the buccal side,open foveas,and well-developed talonids,and P_4s with similarly asymmetrical crown outlines,distinct mesial and distal vertical grooves on the buccal side,and "H" type of grooves combination.These characteristics are also expressed in the later hominin specimens,but with a decreased extent and lower frequency.The P_3s of recent Chinese,slightly asymmetrical in the crown lingual contours,and P_4s,basically symmetrical in the crown outlines,become faint or disappeared in the mesial or distal vertical buccal grooves,and decreased in the talonid size.It is suggested that Zhoukoudian mandibular premolars preserve some primitive traits of earlier hominins,including asymmetrical crown outlines and prominent mesial and distal vertical grooves of buccal side.Moreover,Zhoukoudian specimens exhibit obvious morphological variation between individuals,expressed mainly by aspects of mesial and distal vertical buccal grooves in various degrees,symmetry or asymmetry extent of crown lingual contour,relative location of polygon to the corresponding surrounding outline,as well as the relative size of talonid.When compared with Homo erectus from the other areas of Asia,Zhoukoudian specimens show their similarity with those of Xichuan and S-1,and at the same time great discrepancy with S-6 in the occlusal morphology and crown

  4. Retrofitting a Crown Supporting a Removable Partial Denture Using "Biogeneric Copy" to Replicate Tooth's Preoperative Condition.

    Science.gov (United States)

    Patel, Dhaval

    2016-02-01

    When a crown that supports a removable partial denture (RPD) needs to be replaced, patients often balk at having to wait several weeks for laboratory production to be completed before receiving the new restoration. Moreover, the fit of the lab-produced unit may not always be satisfactory. CEREC® CAD/CAM technology provides a design method known as Biogenetic Copy, which allows a clinician to replicate the preexisting size, shape, and form of a tooth chairside. As this case report demonstrates, using this method to retrofit a crown under an existing RPD prosthesis can result in a predictable, accurate, durable, and esthetic same-day restorative solution. PMID:26905091

  5. 133Cs NMR study of Cs+ ion complexes with dibenzo-21-crown-7 and dibenzo-24-crown-8 in some mixed solvents

    International Nuclear Information System (INIS)

    Complexation of the cesium ion with macrocyclic ligands, dibenzo-21-crown-7 and dibenzo-24-crown-8, was studied in binary solvent mixtures of dimethylsulfoxide with acetone, acetonitrile, propylene carbonate, pyridine and hexamethylphosphoramide (HMPA) as well as in pyridine-methanol mixtures. In the first four binary mixtures the complexation constants increased with decreasing amounts of dimethylsulfoxide (DMSO), the trend is reversed in the DMSO-HMPA system. In all of the above cases, the variation of the stability constant with composition was monotonic and showed good correlation with the inherent solvating ability of the neat solvents which form the mixture. In the pyridine-methanol system, however, for both complexes, the log Ksub(f) vs composition plots show several changes in direction. This behavior is probably due to a change in the structure of this binary solvent as the composition of the medium is varied. (author)

  6. The influence of cervical finish line, internal relief, and cement type on the cervical adaptation of metal crowns

    NARCIS (Netherlands)

    Bottino, Marco Antonio; Valandro, Luiz Felipe; Buso, Leondardo; Oezcan, Mutlu

    2007-01-01

    Objective: The aim of this investigation was to evaluate the cervical adaptation of metal crowns under several conditions, namely (1) variations in the cervical finish line of the preparation, (2) application of internal relief inside the crowns, and (3) cementation using different luting materials.

  7. 77 FR 48582 - In the Matter of Ameriwest Energy Corp., Clyvia, Inc., and Crown Oil & Gas, Inc.; Order of...

    Science.gov (United States)

    2012-08-14

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION In the Matter of Ameriwest Energy Corp., Clyvia, Inc., and Crown Oil & Gas, Inc.; Order of... information concerning the securities of Crown Oil & Gas, Inc. because it has not filed any periodic...

  8. When Does Length Cause the Word Length Effect?

    Science.gov (United States)

    Jalbert, Annie; Neath, Ian; Bireta, Tamra J.; Surprenant, Aimee M.

    2011-01-01

    The word length effect, the finding that lists of short words are better recalled than lists of long words, has been termed one of the benchmark findings that any theory of immediate memory must account for. Indeed, the effect led directly to the development of working memory and the phonological loop, and it is viewed as the best remaining…

  9. Continuously variable focal length lens

    Science.gov (United States)

    Adams, Bernhard W; Chollet, Matthieu C

    2013-12-17

    A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.

  10. Influence of the angle between two crown ether moieties on supramolecular copolymerization of bis(crown ether)s and bisparaquat homoditopic monomers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Bis(crown ether) homoditopic monomers containing two bis(p-phenylene)-34-crown-10 moieties with different angles(180° for monomer 3,120°for monomer 4,and 60°for monomer 5) and a complementary bisparaquat homoditopic monomer(7) were designed and synthesized.The three bis(crown ether) monomers could organize into linear supramolecular polymers in concentrated solutions in CHCl3/CH3CN with the bisparaquat monomer 7,as demonstrated by 1 H NMR and viscosity studies. The pseudorotaxanes or supramolecular polymers formed from 3+7 and 4+7 had larger values of Ka,p,n,slope 1,and slope 2 than those of 5+7.This result was attributed to the greater steric hindrance of compound 5 than that of 3 and 4,which resulted in less effective formation of linear supramolecular polymers from 5 with compound 7 than those from compounds 3 and 4 with compound 7,as also demonstrated by UV-vis method.

  11. Thermodynamics of extraction of Plutonium(VI) in polyEthylene glycol (PEG) based aqueous biphasic system (ABS) using 18-crown-6 and 15-crown-5

    International Nuclear Information System (INIS)

    Extraction of plutonyl ion was studied using PEG-2000/(NH4)2SO4 (40% w/w of each) ABS with 18-crown-6 (18-C-6) as well as 15-crown-5 (15-C-5) as the extractants. The distribution follows the order 18-C-6>15-C-5 in accordance with their basicities of 0.40 and 0.29, respectively. The species extracted were identified to be (PuO2.18-C-6/15-C-5)SO4 by the usual slope ratio method. The thermodynamic parameters evaluated by temperature coefficient method showed that the reaction is favoured by lowering of enthalpy and counteracted by decrease in entropy. The large decrease in the enthalpy values (-20.4±1.8 kJ mol-1 and - 13.2±1.0 kJ mol-1 for 18-C-6 and 15-C-5, respectively) can be explained due to direct bonding of crown ether to the central metal atom (i.e. inner sphere complex) and not through hydrogen bonding as suggested previously by other workers. (orig.)

  12. Graduated compression stockings: knee length or thigh length.

    Science.gov (United States)

    Benkö, T; Cooke, E A; McNally, M A; Mollan, R A

    2001-02-01

    The mechanisms by which graduated compression stockings prevent deep venous thrombosis are not completely understood. In the current study the physiologic effect of low-pressure graduated compression stockings on the venous blood flow in the lower limb and the practical aspects of their use were assessed. Patients having elective orthopaedic surgery at a university orthopaedic department were randomized into five groups to wear two different types of graduated compression stockings in thigh and knee lengths. Patients in the fifth control group did not wear graduated compression stockings. Venous occlusion strain gauge plethysmography was used to measure venous flow. After 20-minutes bed rest there was a highly significant increase in venous capacitance and venous outflow in patients in all of the four groups wearing stockings. There was no difference in the mean of the percentage change of venous capacitance in patients in the four groups wearing stockings. The knee length Brevet stockings were less efficient in increasing the venous outflow. There was no significant change in the venous capacitance and venous outflow in patients in the control group. Visual assessment of the fit and use of stockings was done, and patients' subjective opinion of comfort was sought. The knee length graduated compression stockings wrinkled significantly less, and significantly fewer patients reported discomfort with them. All stockings were reported to be difficult to use. Thigh and knee length stockings have a significant effect on decreasing venous stasis of the lower limb. Knee length graduated compression stockings are similarly efficient in decreasing venous stasis, but they are more comfortable to wear, and they wrinkle less. PMID:11210954

  13. Summary of neutron scattering lengths

    International Nuclear Information System (INIS)

    All available neutron-nuclei scattering lengths are collected together with their error bars in a uniform way. Bound scattering lengths are given for the elements, the isotopes, and the various spin-states. They are discussed in the sense of their use as basic parameters for many investigations in the field of nuclear and solid state physics. The data bank is available on magnetic tape, too. Recommended values and a map of these data serve for an uncomplicated use of these quantities. (orig.)

  14. Slip length measurement using BBM

    Science.gov (United States)

    Ahmadzadegan, Adib; Snoeyink, Craig

    2015-11-01

    We will be presenting experimental characterizations of slip lengths of fluids in nano/micro channels. These channels are becoming increasingly important in sensor and separations applications. However, crucial questions still remain on the mechanisms that govern slip-length behavior. We used Bessel Beam microscopy (BBM), a novel super-resolution imaging system, in conjunction with TIRF system. These two, together led us to be able to do Particle Tracking Velocimetry with significantly higher accuracy than previously possible. We will be presenting results demonstrating the feasibility of this approach and advantages that make this method unique.

  15. The effect of different surface treatments of stainless steel crown and different bonding agents on shear bond strength of direct composite resin veneer

    Directory of Open Access Journals (Sweden)

    Ajami B

    2007-01-01

    Full Text Available Background and Aim: Stainless steel crown (SSC is the most durable and reliable restoration for primary teeth with extensive caries but its metalic appearance has always been a matter of concern. With advances in restorative materials and metal bonding processes, composite veneer has enhanced esthetics of these crowns in clinic. The aim of this study was to evaluate the shear bond strength of SSC to composite resin using different surface treatments and adhesives. Materials and Methods: In this experimental study, 90 stainless steel crowns were selected. They were mounted in molds and divided into 3 groups of 30 each (S, E and F. In group S (sandblast, buccal surfaces were sandblasted for 5 seconds. In group E (etch acidic gel was applied for 5 minutes and in group F (fissure bur surface roughness was created by fissure diamond bur. Each group was divided into 3 subgroups (SB, AB, P based on different adhesives: Single Bond, All Bond2 and Panavia F. Composite was then bonded to specimens. Cases were incubated in 100% humidity at 37°C for 24 hours. Shear bond strength was measured by Zwick machine with crosshead speed of 0.5 mm/min. Data were analyzed by ANOVA test with p0.05 so the two variables were studied separately. No significant difference was observed in mean shear bond strength of composite among the three kinds of adhesives (P>0.05. Similar results were obtained regarding surface treatments (P>0.05. Conclusion: Based on the results of this study, treating the SSC surface with bur and using single bond adhesive and composite can be used successfully to obtain esthetic results in pediatric restorative treatments.

  16. Effect of water temperature on the fit of provisional crown margins during polymerization: An in vitro study

    Directory of Open Access Journals (Sweden)

    Vivekanandan Ramkumar

    2012-01-01

    Full Text Available Aim: To evaluate the effect of water temperature on the marginal fit of bis-acrylic composite provisional crown during resin polymerization. Materials and Methods: Precisely machined 10 brass master dies were designed to simulate molar teeth. Five brass dies were selected and precisely machined to simulate all ceramic crown preparation. An acrylic jaw replica was made in which brass dies were arranged equidistant from each other. A custom-made metallic tray was fabricated on the acrylic jaw replica to make polyvinyl siloxane impression matrix. Bis-acrylic composite resin provisional crowns were made using polyvinyl siloxane impression matrix. Provisional crowns were polymerized at room temperature (Group I direct technique, on dental stone cast; Group I indirect technique crowns and at different water temperatures (Group II direct technique crowns. The vertical marginal gap between all the provisional crown margins and the finish line of brass dies was measured using a Research Stereomicroscope System. Results: The results were statistically analyzed using one-way analysis of variance (ANOVA test and Newman-Keul′s test. The results showed that crowns polymerized in 20°C and 30°C water had marginal gap approximately three times smaller than those polymerized in 30°C air, due to the reduced polymerization shrinkage. Conclusion: This study shows that crowns polymerized in 20°C and 30°C water had mean vertical marginal gap approximately three times smaller than those polymerized in 30°C air. It was approximately closer to that of crowns fabricated by indirect technique. Warmer water also supposedly hastens polymerization.

  17. 应用烤瓷套冠修补崩瓷冠桥的可行性研究%Feasibility of repairing collapsed crown and fixed bridge by porcelain jacket crown

    Institute of Scientific and Technical Information of China (English)

    顾振宇; 何惠宇; 蔡天恒; 田媛

    2014-01-01

    BACKGROUND:Porcelain jacket crowns have achieved good results in the repair of porcelain ceramic crown and bridge colapse. OBJECTIVE:To test the bond strength of single porcelain jacket crown, thus determining the feasibility of clinical application of repairing colapsed crown and fixed bridge by porcelain jacket crown, and meanwhile to discuss the influence between blastsanding and silane coupling agent treatment on the metal bonding strength in the repair of porcelain fracture. METHODS: The porcelain jacket crown was cast in the same shape from disk-shaped waxpatterns. Twenty specimens were chosen without blowholes and casting defects and they were al routinely burnished and cleaned in an ultrasonic bath and dried using an oil-free air stream stand-by. Then we randomly divided the specimens into four groups: specimens were treated with nothing (control), sandblast, silane coupling agent and sandblast+silane coupling agent, respectively. Each of the specimen was bonded with Poly-F Plus. AG-10TA universal testing machine was used to test the tensile strength. RESULTS AND CONCLUSION:The tensile bond strength of control, sandblast, silane coupling agent and sandblast+silane coupling agent groups respectively were (0.68 0.04), (1.00 0.02), (1.31 0.08), and (1.09 0.04) kN. There were significant differences between groups (P   目的:检测烤瓷套冠单冠黏结强度的大小,判断烤瓷套冠在修补崩瓷临床应用中的可行性,同时观察烤瓷套冠修复崩瓷过程中喷砂处理和硅烷偶联剂处理金属黏结表面对其黏结强度的影响。  方法:用失蜡法铸造相同规格钴铬合金套冠,选择表面无气孔、无铸造缺陷的试件20件,常规打磨,超声清洗后随机分为4组,分别进行喷砂处理、硅烷偶联剂处理及喷砂+硅烷偶联剂处理,以未作任何处理的为对照组。将处理后的试件用聚羧酸锌水门汀进行黏结,采用万能力学测试仪测试拉伸强度。

  18. The Interaction between Rice ERF3 and WOX11 Promotes Crown Root Development by Regulating Gene Expression Involved in Cytokinin Signaling[OPEN

    Science.gov (United States)

    Song, Yaling; Huang, Yulan

    2015-01-01

    Crown roots are the main components of the fibrous root system in rice (Oryza sativa). WOX11, a WUSCHEL-related homeobox gene specifically expressed in the emerging crown root meristem, is a key regulator in crown root development. However, the nature of WOX11 function in crown root development has remained elusive. Here, we identified a rice AP2/ERF protein, ERF3, which interacts with WOX11 and was expressed in crown root initials and during crown root growth. Functional analysis revealed that ERF3 was essential for crown root development and acts in auxin- and cytokinin-responsive gene expression. Downregulation of ERF3 in wox11 mutants produced a more severe root phenotype. Also, increased expression of ERF3 could partially complement wox11, indicating that the two genes functioned cooperatively to regulate crown root development. ERF3 and WOX11 shared a common target, the cytokinin-responsive gene RR2. The expression of ERF3 and WOX11 only partially overlapped, underlining a spatio-temporal control of RR2 expression and crown root development. Furthermore, ERF3-regulated RR2 expression was involved in crown root initiation, while the ERF3/WOX11 interaction likely repressed RR2 during crown root elongation. These results define a mechanism regulating gene expression involved in cytokinin signaling during different stages of crown root development in rice. PMID:26307379

  19. Crystal structure of di-aqua-[5,10,15,20-tetra-kis-(4-meth-oxy-phen-yl)porphyrinato-κ(4) N]iron(III) di-aqua-(18-crown-6)potassium bis-(tri-fluoro-methane-sulfonate)-18-crown-6 (1/2).

    Science.gov (United States)

    Ben Haj Hassen, Leila; Denden, Zouhour; Rousselin, Yoann; Nasri, Habib

    2015-12-01

    In the title compound, [Fe(III)(C48H36N4O2)(H2O)2][K(C12H24O6)(H2O)2](SO3CF3)2·2C12H24O6, the Fe(III) atom is situated on an inversion centre and is octa-hedrally coordin-ated by four pyrrole N atoms of the deprotenated 5,10,15,20-tetra-kis-(4-meth-oxy-phen-yl)porphyrinate ligand and two water mol-ecules. The average equatorial Fe-N(pyrrole) bond length [2.043 (6) Å] is consistent with a high-spin (S = 5/2) iron(III) metalloporphyrin derivative. The K(+) cation, which also lies on an inversion centre, is chelated by the six O atoms of one 18-crown-6 mol-ecule and is additionally coordinated by two water mol-ecules in a distorted hexa-gonal-bipyramidal geometry. In the crystal, the cations, anions and one non-coordinating 18-crown-6 mol-ecule are linked by classical O-H⋯O hydrogen bonds and non-conventional C-H⋯O hydrogen bonds, leading to a one-dimensional supra-molecular architecture along [10-1]. The crystal packing is further stabilized by weak C-H⋯π inter-actions involving pyrrole and phenyl rings of the porphyrins, as well as weak C-H⋯F contacts involving the (SO3CF3)(-) counter-ion and the 18-crown-6 mol-ecules. PMID:26870431

  20. Remark on pion scattering lengths

    CERN Document Server

    Black, Deirdre; Jora, Renata; Park, Nae Woong; Schechter, Joseph; Shahid, M Naeem

    2009-01-01

    It is noted that the pattern of chiral perturbation theory predictions for both the isotopic spin 0 and isotopic spin 2 s-wave pion-pion scattering lengths to orders $p^2$, $p^4$ and $p^6$ seems to agree with the corresponding pattern of the tree level predictions of the SU(2) linear sigma model.

  1. Cavity length below chute aerators

    Institute of Scientific and Technical Information of China (English)

    WU JianHua; RUAN ShiPing

    2008-01-01

    It is proved that air entrainment is one of the efficient measures dealing with cavitation control for the release works of hydropower projects. There are many factors to be considered in designing a chute aerator. One of the most important factors concerns the cavity length below the aerator, which has outstanding effects on air entrainment against cavitation damage. It is crucial to determine reasonable emergence angle for the calculation of the cavity length. In the present paper the overall effects of structural and hydraulic parameters on the emergence angle of the flow from the aerator were analyzed. Four improved expressions of the emergence angle with weight coefficient were investigated through experimental data of 68 points observed from 12 aerators of 6 hydropower projects, of both model and prototype, on the basis of error theory. A method to calculate the cavity length below aerators was suggested, which considers overall effects of the above mentioned parameters. Comparison between the method in this paper and the other five methods of calculating the cavity length showed that the present method is much more reliable than the existing methods while the mean error of the method is less than others.

  2. Cavity length below chute aerators

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is proved that air entrainment is one of the efficient measures dealing with cavi-tation control for the release works of hydropower projects. There are many factors to be considered in designing a chute aerator. One of the most important factors concerns the cavity length below the aerator,which has outstanding effects on air entrainment against cavitation damage. It is crucial to determine reasonable emergence angle for the calculation of the cavity length. In the present paper the overall effects of structural and hydraulic parameters on the emergence angle of the flow from the aerator were analyzed. Four improved expressions of the emer-gence angle with weight coefficient were investigated through experimental data of 68 points observed from 12 aerators of 6 hydropower projects,of both model and prototype,on the basis of error theory. A method to calculate the cavity length be-low aerators was suggested,which considers overall effects of the above men-tioned parameters. Comparison between the method in this paper and the other five methods of calculating the cavity length showed that the present method is much more reliable than the existing methods while the mean error of the method is less than others.

  3. Cyclic Codes of Length 2

    Indian Academy of Sciences (India)

    Manju Pruthi

    2001-11-01

    In this paper explicit expressions of + 1 idempotents in the ring $R = F_q[X]/\\langle X^{2^m}-1\\rangle$ are given. Cyclic codes of length 2 over the finite field , of odd characteristic, are defined in terms of their generator polynomials. The exact minimum distance and the dimension of the codes are obtained.

  4. Seismic Hazard and Fault Length

    Science.gov (United States)

    Black, N. M.; Jackson, D. D.; Mualchin, L.

    2005-12-01

    If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern California. In this study, we found that mapped fault length and rupture length are often unequal, and in several cases rupture broke beyond the previously mapped fault traces. To expand the geologic definition of fault length we outlined several guidelines: 1) if a fault truncates at young Quaternary alluvium, the fault line should be inferred underneath the younger sediments 2) faults striking within 45° of one another should be treated as a continuous fault line and 3) a step-over can link together faults at least 5 km apart. These definitions were applied to fault lines in Southern California. For example, many of the along-strike faults lines in the Mojave Desert are treated as a single fault trending from the Pinto Mountain to the Garlock fault. In addition, the Rose Canyon and Newport-Inglewood faults are treated as a single fault line. We used these more generous fault lengths, and the Wells and Coppersmith regression, to estimate the maximum magnitude (mx) for the major faults in

  5. Utilizing CAD/CAM to Measure Total Occlusal Convergence of Preclinical Dental Students' Crown Preparations.

    Science.gov (United States)

    Mays, Keith A; Crisp, H Alex; Vos, Paul

    2016-01-01

    Traditionally, faculty assessment of preclinical crown preparations occurs by visualizing preparation features. However, contemporary CAD/CAM tools have the ability to more precisely evaluate preparation features, which is beneficial for psychomotor development. Taper is one of the most challenging features to objectively assess. The aim of this study was twofold: first, to validate the software's ability to distinguish differences in taper, and second, to compare traditional faculty assessment with digital assessment of taper. In the study, 30 all-metal crown preparations were created on typodont teeth with varying degrees of axial reduction and placed into three groups based on amount of taper (minimum, moderate, or excessive). Each tooth was scanned with the D4D scanner, and the taper was analyzed using E4D Compare. A second experiment used 50 crown preparations of tooth #19, which were done as a formative exercise. A comparison faculty assessment with CAD/CAM assessments of taper was performed. The results showed that when the taper was varied, E4D Compare was able to distinguish those differences; the Tukey post-hoc test revealed a significant difference (p=0.001). The qualitative analysis comparing faculty grading to CAD/CAM grading demonstrated a trend for CAD/CAM to be more precise. These results suggest that E4D Compare is an effective means of quantitatively measuring the amount of total occlusal convergence or taper on a crown preparation and that digital assessment may be more precise than faculty visual grading. PMID:26729690

  6. Polyaza crown ether as non-nucleosidic building blocks in DNA-conjugates

    DEFF Research Database (Denmark)

    Jakobsen, Ulla; Rohr, Katja; Madsen, Rasmus K;

    2007-01-01

    The synthesis of amphiphilic polyaza crown ether monomers X (palmityl-substituted), Y (cholesteryl-substituted) and Z (dipalmityl-subtituted) and their incorporation into oligonucleotides are described. Their effects on thermal duplex stability were investigated by UV melting curve analysis. Ther...

  7. Estimating average tree crown size using high-resolution airborne data

    Czech Academy of Sciences Publication Activity Database

    Brovkina, Olga; Latypov, I.; Cienciala, E.

    2015-01-01

    Roč. 9, may 13 (2015), 096053-1-096053-13. ISSN 1931-3195 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk OC09001 Institutional support: RVO:67179843 Keywords : crown size * airborne data * spruce * granulometry Subject RIV: EH - Ecology, Behaviour Impact factor: 1.183, year: 2014

  8. Micro-CT evaluation of the marginal fit of CAD/CAM all ceramic crowns

    Science.gov (United States)

    Brenes, Christian

    Objectives: Evaluate the marginal fit of CAD/CAM all ceramic crowns made from lithium disilicate and zirconia using two different fabrication protocols (model and model-less). METHODS: Forty anterior all ceramic restorations (20 lithium disilicate, 20 zirconia) were fabricated using a CEREC Bluecam scanner. Two different fabrication methods were used: a full digital approach and a printed model. Completed crowns were cemented and marginal gap was evaluated using Micro-CT. Each specimen was analyzed in sagittal and trans-axial orientations, allowing a 360° evaluation of the vertical and horizontal fit. RESULTS: Vertical measurements in the lingual, distal and mesial views had and estimated marginal gap from 101.9 to 133.9 microns for E-max crowns and 126.4 to 165.4 microns for zirconia. No significant differences were found between model and model-less techniques. CONCLUSION: Lithium disilicate restorations exhibited a more accurate and consistent marginal adaptation when compared to zirconia crowns. No statistically significant differences were observed when comparing model or model-less approaches.

  9. Rhizoctonia crown and root rot resistance evaluation of Beta PIs in Fort Collins, CO, 2015

    Science.gov (United States)

    Thirty beet accessions of either cultivated beet or sea beet (Beta vulgaris subsp. vulgaris or Beta vulgaris subsp. maritima (L.) Arcang) from the Beta collection of the USDA-Agricultural Research Service National Plant Germplasm System were screened for resistance to Rhizoctonia crown and root rot ...

  10. Liquid Membrane Transport Behavior of Functional Substituted Crown Ethers for Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Three functional substituted crown ethers were synthesized as liquid membrane transport carriers for amino acids. The result obtained shows that this kind of ditopic ligands can transport sodium salt of amino acids in good rate value especially the one with two pyridinyl groups as binding site outside the macrocycle.

  11. Nanocomposite Langmuir-Blodgett films based on crown derivatized platinum nanoparticles: Synthesis, characterization, and electrical properties

    International Nuclear Information System (INIS)

    This paper deals with the crown derivatization of 4-mercaptoaniline functionalized platinum formation and the use of the resulting nanoparticles to build up controlled Langmuir and Langmuir-Blodgett films. It is shown that the high density of amine functions at the surface of platinum nanoparticles functionalized by 4-mercaptoaniline offers the possibility of over grafting with various molecules giving rise to different rate of crown derivatization ranging from 19% to 45%. The derivatizations process of the organic coating has been characterized by infrared spectroscopy and thermo gravimetric analysis. The elaboration of Langmuir and Langmuir-Blodgett films containing different ratio of derivatized nanoparticles and fatty acid is reported and the thin films are characterized using X-ray photoelectron spectroscopy and small-angle X-ray scattering. A marked structural anisotropy due to the deposition process is revealed, that corresponds in some cases to a well-defined layered organisation. Modifications in electrical conductivity induced by crown derivatization are reported. These crown derivatized particles are currently studied towards the oxygen reduction reaction

  12. Nanocomposite Langmuir-Blodgett films based on crown derivatized platinum nanoparticles: Synthesis, characterization, and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Henri [Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM-CNRS URA 2453 Bat. 522, 91191 Gif-sur-Yvette (France)], E-mail: henri.perez@cea.fr; Noel, Vincent [Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM-CNRS URA 2453 Bat. 522, 91191 Gif-sur-Yvette (France); Cavaliere-Jaricot, Sara [Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM-CNRS URA 2453 Bat. 522, 91191 Gif-sur-Yvette (France); Institut Lavoisier (IREM, UMR 8637 CNRS), Universite de Versailles-Saint Quentin, 45 ave des Etats-Unis, 78035 Versailles (France); Etcheberry, Arnaud [Institut Lavoisier (IREM, UMR 8637 CNRS), Universite de Versailles-Saint Quentin, 45 ave des Etats-Unis, 78035 Versailles (France); Albouy, Pierre-Antoine [Laboratoire de Physique des Solides (U.M.R. 8502), Bat 510 Universite Paris-Sud, 91405 Orsay (France)

    2008-11-28

    This paper deals with the crown derivatization of 4-mercaptoaniline functionalized platinum formation and the use of the resulting nanoparticles to build up controlled Langmuir and Langmuir-Blodgett films. It is shown that the high density of amine functions at the surface of platinum nanoparticles functionalized by 4-mercaptoaniline offers the possibility of over grafting with various molecules giving rise to different rate of crown derivatization ranging from 19% to 45%. The derivatizations process of the organic coating has been characterized by infrared spectroscopy and thermo gravimetric analysis. The elaboration of Langmuir and Langmuir-Blodgett films containing different ratio of derivatized nanoparticles and fatty acid is reported and the thin films are characterized using X-ray photoelectron spectroscopy and small-angle X-ray scattering. A marked structural anisotropy due to the deposition process is revealed, that corresponds in some cases to a well-defined layered organisation. Modifications in electrical conductivity induced by crown derivatization are reported. These crown derivatized particles are currently studied towards the oxygen reduction reaction.

  13. First Report of Crown Gall Caused by Agrobacterium sp. on Diffuse Knapweed (Centaurea diffusa)

    Science.gov (United States)

    A specimen of diffuse knapweed (Centaurea diffusa, DK) with crown gall-like symptoms was collected July 27, 2004, in Mosier, Wasco Co., OR (N 45.6842, W 121.4021), and sent to the USDA at Ft. Detrick, MD, for identification. A bacterium was isolated on Potato Dextrose Agar that caused hyperplasia a...

  14. Sethian Crowns, Sethian Martyrs? Jewish Apocalypses and Christian Martyrs in a Gnostic Literary Tradition

    DEFF Research Database (Denmark)

    Burns, Dylan Michael

    2014-01-01

    . Thirdly, Plotinus’ Christian Gnostic opponents may have seen these crowns differently — as indicative of the glory of martyrdom, reminding us that this early confrontation between Hellenic and Christian Gnostic philosophers followed on the heels of the Decian and Valerianic persecutions....

  15. CROWN GALL INCIDENCE: SEEDLING PARADOX WALNUT ROOTSTOCK VERSUS OWN-ROOTED ENGLISH WALNUT TREES

    Science.gov (United States)

    Seedling Paradox (Juglans hindsii x J. regia) has been the rootstock of choice for English walnut in California because of its vigor and greater tolerance of wet soil conditions. However, seedling Paradox rootstock is highly susceptible to crown gall, a disease caused by the soil-borne bacterium Agr...

  16. Mass spectra of alkaline earth salts with a FAB source. Complexation with crown ethers

    International Nuclear Information System (INIS)

    With a liquid desorption FAB source it is possible to obtain alkaline earth metal ions complexed by a crown ether. Conditions for formation of these complexes ions are examined for selection of the complexing agent in function of cation size. Behaviour of alkaline and alkaline earth compounds are compared allowing the differentiation of ion extraction phenomena by liquid desorption ion source and solvent extraction

  17. URS Brava – a new oat cultivar with partial resistance to crown rust

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Federizzi

    2015-08-01

    Full Text Available The cultivar URS Brava, obtained from a simple cross between the line ‘UFRGS 995078-2’ and the cultivar ‘URS 21’, shows high grain yield and stability, high grain quality, desirable agronomical traits and partial resistance to crown rust, caused by the fungus Puccinia coronata f. sp. avenae.

  18. Stability of Monolithic Rubble Mound Breakwater Crown Walls Subjected to Impulsive Loading

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Lars Vabbersgaard; Andersen, Thomas Lykke; Burcharth, Hans F.

    2012-01-01

    This paper evaluates the validity of a simple onedimensional dynamic analysis as well as a FEM model to determine the sliding of a rubble mound breakwater crown wall. The evaluation is based on a case example with real wave load time series and displacements measured from two-dimensional physical...

  19. Low-polarity electrolytes on the base of crown ether complexes with alkali metal ions

    International Nuclear Information System (INIS)

    New low-polar electrolytes on the basis of 15-crown-5 complexes with alkali metal (lithium, sodium) ions in solvent characterized by low dielectrical permittivity: benzene, toluene, ethylene glycol dimethyl ether, tetrahydrofuran and methylene chloride, characterized by specific electrical permittivity equal to 10-5-10-2 Ohm-1·cm-1, are suggested and studied. 15 refs., 2 figs.,

  20. Can hyaluronan injections augment deficient papillae at implant-supported crowns in the anterior maxilla?

    DEFF Research Database (Denmark)

    Bertl, Kristina; Gotfredsen, Klaus; Jensen, Simon S;

    2016-01-01

    OBJECTIVES: The present randomized controlled trial aimed to assess the effect of hyaluronan (HY) injections to augment deficient interproximal papillae at implant-supported crowns in the anterior maxilla. METHODS: Twenty-two patients with a deficient papilla in the anterior maxilla next to an...

  1. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    Gamez, F.; Hurtado, P.; Martinez-Haya, B.; G. Berden,; Oomens, J.

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg(2+), Ca(2+). Sr(2+) and Ba(2+)) stored in the cell of a Fourier Transform Ion Cyclotron Resonan

  2. Vibrational study of isolated 18-crown-6 ether complexes with alkaline-earth metal cations

    NARCIS (Netherlands)

    F. Gámez; P. Hurtado; B. Martínez-Haya; G. Berden; J. Oomens

    2011-01-01

    Laser infrared multiple photon dissociation (IRMPD) spectroscopy has been employed to probe the C-O and C-C stretching vibrational modes of 18-crown-6 ether (18c6) complexes with alkaline-earth metals (Mg2+, Ca2+, Sr2+ and Ba2+) stored in the cell of a Fourier Transform Ion Cyclotron Resonance mass

  3. Resistance in watermelon rootstocks to crown rot caused by Phytophthora capsici

    Science.gov (United States)

    Phytophthora crown and fruit rot caused by Phytophthora capsici is becoming an important and emerging disease of watermelon (Citrullus lanatus) in south eastern United States. In recent years, the practice of grafting seedless watermelons (triploids) onto rootstocks belonging to other Cucurbitaceae...

  4. Effect of phytophthora capsici crown rot on watermelon rootstocks and grafts

    Science.gov (United States)

    Crown and fruit rot caused by Phytophthora capsici is becoming an important and emerging disease of watermelon in the southeastern United States. In recent years, the practice of grafting seedless watermelons onto rootstocks belonging to other Cucurbitaceae genera is also gaining acceptance in our l...

  5. Modification of tolerance of oats to crown rust induced by chemical mutagens

    International Nuclear Information System (INIS)

    Seeds of crown rust (Puccinia coronata) susceptible cultivated oats (Avena sativa) were treated with the mutagenic chemical ethyl methanesulphonate (EMS), and pure lines derived from these treated seeds were tested in later generations for the relative amount of reduction in yield and seed weight caused by crown rust infection. In the absence of crown rust, the yield of most of the treated lines was greatly reduced. The overall means of the treated lines for both yield and seed weight response to infection were significantly lower than the control, but 10 lines significantly exceeded the control for yield response and 15 exceeded it for seed weight response. Recurrent EMS treatment of once-treated lines rated as tolerant resulted in groups of lines that were more tolerant, on the average, than groups of lines from recurrently treated lines rated as susceptible. A few of the recurrently treated individual lines derived from tolerant parents had a higher degree of tolerance than their parental lines. EMS treatment of diploid (A. strigosa) and tetraploid (A. abyssinica) oats resulted in groups of lines showing significant genetic variance for response to crown rust, indicating that treatment had induced real genetic change. A few diploid lines were a little more tolerant than their control, but none of the tetraploid lines showed any consistent improvement. (author)

  6. Rainforest air-conditioning: the moderating influence of epiphytes on the microclimate in tropical tree crowns

    Science.gov (United States)

    Stuntz, Sabine; Simon, Ulrich; Zotz, Gerhard

    2002-05-01

    Epiphytes are often assumed to influence the microclimatic conditions of the tree crowns that they inhabit. In order to quantify this notion, we measured the parameters "temperature" (of the substrate surface and the boundary layer of air above it), "evaporative drying rate" and "evapotranspiration" at various locations within tree crowns with differing epiphyte assemblages. The host tree species was Annona glabra, which was either populated by one of three epiphyte species ( Dimerandra emarginata, Tillandsia fasciculata, or Vriesea sanguinolenta) or was epiphyte-free. We found that during the hottest and driest time of day, microsites in the immediate proximity of epiphytes had significantly lower temperatures than epiphyte-bare locations within the same tree crown, even though the latter were also shaded by host tree foliage or branches. Moreover, water loss through evaporative drying at microsites adjacent to epiphytes was almost 20% lower than at exposed microsites. We also found that, over the course of several weeks, the evapotranspiration in tree crowns bearing epiphytes was significantly lower than in trees without epiphytes. Although the influence of epiphytes on temperature extremes and evaporation rates is relatively subtle, their mitigating effect could be of importance for small animals like arthropods inhabiting an environment as harsh and extreme as the tropical forest canopy.

  7. Next generation sequencing of crown and rhizome transcriptome from an upland, tetraploid switchgrass

    Science.gov (United States)

    The crown and rhizome transcriptome of a winter-adapted, upland tetraploid switchgrass cultivar Summer, was investigated using the Roche 454-FLX pyrosequencing platform. In all approximately 1 million reads consisting of 216 million bases were assembled into 27,687 contigs and 43,094 singletons. A...

  8. Evaluation of Pseudomonas syringae Strain ESC11 for Biocontrol of Crown Rot and Anthracnose of Banana

    Science.gov (United States)

    Pseudomonas syringae strain ESC11, and 250 'g/ml each of thiabendazole (TBZ) and imazalil reduced crown rot of banana caused by a Fusarium sp. by 0-88% and 73-88%, respectively, in laboratory experiments. ESC11 alone did not significantly reduce rot, mold, or anthracnose in most field trials. TBZ an...

  9. Stereochemistry effect of dicyclohexano-18-crown-6 on zinc isotope separation

    International Nuclear Information System (INIS)

    Zinc isotope fractionation is reported with the pure cis-syn-cis and cis-anti-cis stereoisomers of dicyclohexano-18-crown-6. These structures contribute differently to the enrichment of the Zn isotopes, and the best fractionation was obtained with the cis-syn-cis derivative. (authors)

  10. Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants.

    Science.gov (United States)

    Traini, Tonino; Sorrentino, Roberto; Gherlone, Enrico; Perfetti, Federico; Bollero, Patrizio; Zarone, Ferdinando

    2015-07-01

    Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns. PMID:24779915

  11. Evolution of M1 crown size and cusp proportions in the genus Homo.

    Science.gov (United States)

    Quam, Rolf; Bailey, Shara; Wood, Bernard

    2009-05-01

    Previous research into tooth crown dimensions and cusp proportions has proved to be a useful way to identify taxonomic differences in Pliocene and Pleistocene fossil hominins. The present study has identified changes in both M(1) crown size and cusp proportions within the genus Homo, with M(1) overall crown size reduction apparently occurring in two main stages. The first stage (a reduction of ca. 17%) is associated with the emergence of Homo ergaster and Homo erectus sensu stricto. The second stage (a reduction of ca. 10%) occurs in Homo sapiens, but the reduced modern human M(1) tooth crown size was only attained in Upper Paleolithic times. The absolute sizes of the individual cusps are highly positively correlated with overall crown size and dental reduction produces a reduction in the absolute size of each of the cusps. Most of the individual cusps scale isometrically with crown size, but the paracone shows a negative allometric relationship, indicating that the reduction in paracone size is less than in the other M(1) cusps. Thus, the phylogenetically oldest cusp in the upper molars also seems to be the most stable cusp (at least in the M(1)). The most striking change in M(1) cusp proportions is a change in the relative size of the areas of the paracone and metacone. The combination of a small relative paracone and a large relative metacone generally characterizes specimens attributed to early Homo, and the presence of this character state in Australopithecus and Paranthropus suggests it may represent the primitive condition for the later part of the hominin clade. In contrast, nearly all later Homo taxa, with the exception of Homo antecessor, show the opposite condition (i.e. a relatively large paracone and a relatively small metacone). This change in the relationship between the relative sizes of the paracone and metacone is related to an isometric reduction of the absolute size of the metacone. This metacone reduction occurs in the context of relative

  12. The Belmont Report: The Triple Crown of Research Ethics.

    Science.gov (United States)

    Miracle, Vickie A

    2016-01-01

    The Belmont Report is a critical document for those involved in research. However, the report is also applicable to clinical practice. The primary purpose of the Belmont Report is to protect the rights of all research subjects or participants. The Belmont Report also serves as an ethical framework for research. There are 3 major components: (1) respect for persons, (2) beneficence, and (3) justice. This article will review these principles and show how they can be applied to the clinical as well as the research setting and address some concerns for the 21st century. PMID:27258959

  13. Restorasi mahkota logam dengan pasak fiber komposit pada molar permanen muda (Metal crown restoration with fiber composite post in young permanent molar

    Directory of Open Access Journals (Sweden)

    Theresia Dhearine Pratiwi

    2013-09-01

    Full Text Available Background: The first permanent molar has a high prevalence of caries with the most rapid progression in the first two years after eruption. The destruction can extend to the pulp and require endodontic treatment. After endodontic treatment the teeth should have a final restoration due to the possibilities of fracture. The teeth with a few remaining tissue need a restoration such as crown with post and core support. Fiber composite post is widely used today because it has a similar modulus elasticity as dentin. Purpose: The case report was aimed to share the endodontic treatment which was followed by fiber composite post and metal crown insertion on young permanent molar. Case: An 11 years old girls was referred to Pediatric Dentistry clinic at Universitas Indonesia Dental Hospital due to caries #36 that extend to the pulp. Case management: Endodontic treatment with metal crown supported by fiber composite post and composite core was done as final restoration. One month after procedure there was no subjective complaints or inflammation. Conclusion: The case report showed that endodontic treatment followed by fiber composite post and metal crown insertion could be done succesfully on young permanent molar of 11 years old patient.Latar belakang: Gigi molar pertama permanen muda (M1 merupakan gigi dengan angka kejadian karies yang tinggi dengan kerusakan paling cepat terjadi pada dua tahun pertama setelah gigi tersebut erupsi. Kerusakan tersebut dapat mencapai pulpa sehingga diperlukan perawatan endodontik. Gigi yang sudah dirawat memerlukan restorasi akhir yang baik, karena kemungkinan terjadi fraktur. Sisa jaringan gigi yang sedikit membutuhkan restorasi akhir berupa mahkota tiruan dengan dukungan pasak dan inti. Pasak fiber komposit merupakan pasak yang saat ini sering digunakan karena memiliki keunggulan modulus elastisitas yang menyerupai dentin. Tujuan: Tujuan penulisan laporan kasus ini adalah untuk melaporkan perawatan endodontik yang

  14. Three Kinds of Crown Repairing Marginal Fit Efficiency Comparing%三种全冠修复边缘适合性效果对比

    Institute of Scientific and Technical Information of China (English)

    张晓正

    2014-01-01

    Objective To repairing ef ects on marginal adaptation of Ni-Cr al oy porcelain crowns,al-ceramic crowns and metal ceramic crowns compared to guide clinical treatment. Methods According to the teeth conditions and needs of patients,use Ni-Cr al oy porcelain teeth,dental precious metal ceramic and al -ceramic dental restoration to repair,one year after referral to observe al the objects in gingival color,gingival index and marginal fit. Results Ni-Cr al oy porcelain teeth marginal fit of Class A accounted for 86.5%.accounting for 95.1%of Class A of the marginal fit of precious metal porcelain tooth edge.al -cerainlc dental marginal fit of Class A accounted for 96.6%. Conclusion For the Ni-Cr al oy porcelain teeth,crowns fit is poor and the binder dissolution caused by the local pigment deposi-tion is the main reason to cause periodontal damage caused by gum color change.Al-ceramic dental and precious metal ceramic teeth has go d biocompatibility and marginal adaptation of virtual y no efect on the color of the gums and gingival index.%目的:对比三种全冠修复的边缘适合性效果进行对比,以指导临床的治疗。方法根据临床完成的镍铬合金烤瓷冠、贵金属烤瓷冠和全瓷冠修复,1年后复诊观察所有全冠的边缘适合性。结果镍铬合金烤瓷牙边缘适合性A级的占86.5%,贵金属烤瓷牙边缘适合性A级的占95.1%,全瓷牙边缘适合性 A级的占96.6%。结论对于镍铬合金烤瓷冠边缘的密合性差,而全瓷冠与贵金属烤瓷冠具有很好的边缘适合性。

  15. The Effect of Different Finishing Lines on the Marginal Fitness of Full Contour Zirconia and Glass Ceramic CAD/CAM Crowns (An in-vitro study

    Directory of Open Access Journals (Sweden)

    ZAK Al-Zubaidi

    2015-09-01

    Full Text Available Purpose: The aim of this study was to evaluate the effect of two gingival finishing lines (90° shoulder and deep chamfer on the marginal fitness of two types of full anatomic all-ceramic crowns; zirconia crowns (Zikonzhan and glass ceramic crowns (IPS e-max CAD milled with CAD/CAM system. Materials and Methods: Two dentoform teeth of left maxillary first molar were prepared with chamfer finishing line (CFL and shoulder finishing line (SFL, respectively and duplicated to Nickel-Chromium master dies. Thirty two crowns were fabricated and grouped as follows: Group I: 8 zirconia crowns on CFL; Group II: 8 zirconia crowns on SFL; Group III: 8 glass ceramic crowns on CFL and Group IV: 8 glass ceramic crowns on SFL. Marginal gaps were measured at 4 indentations, each one was at center of each tooth surface and collectively 16 points were measured by using stereomicroscope (160X. The data were analyzed by One-way ANOVA and student t-tests. Results: Group I produced the least marginal gap (73.55µm; followed by Group II (92.60µm, and Group III (151.45µm and the highest marginal gap was recorded by Group IV (162.34µm. Statistical analysis of the data showed that SFL produced significantly greater marginal gap on zirconia crowns in comparison with CFL. However, in glass ceramic crowns, CFL revealed less marginal gap compared to SFL but statistically was not significant. On the other hand, glass ceramic crowns significantly produced a greater marginal gap in comparison to zirconia crowns regardless type of finishing line. Conclusions: deep chamfer margin could be more preferable finishing line than 90° shoulder especially for zirconia full crowns. Furthermore, zirconia crowns could be more advisable than glass ceramic crowns in respect to marginal adaptation.

  16. Correlation between margin fit and microleakage in complete crowns cemented with three luting agents

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Orlato Rossetti

    2008-02-01

    Full Text Available Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with either zinc phosphate (ZP (S.S. White, resin-modified glass-ionomer (RMGI (Rely X Luting Cement or a resin-based luting agent (RC (Enforce. Margin fit (seating discrepancy and margin gap was evaluated according to criteria in the literature under microscope with 0.001 mm accuracy. After thermal cycling, crowns were longitudinally sectioned and microleakage scores at tooth-cement interface were obtained and recorded at ×100 magnification. Margin fit parameters were compared with the one-way ANOVA test and microleakage scores with Kruskal-Wallis and Dunn's tests (alpha=0.05. Correlation between margin fit and microleakage was analyzed with the Spearman's test (alpha=0.05. Seating discrepancy and marginal gap values ranged from 81.82 µm to 137.22 µm (p=0.117, and from 75.42 µm to 78.49 µm (p=0.940, respectively. Marginal microleakage scores were ZP=3.02, RMGI=0.35 and RC=0.12 (p0.05. Conclusion: Margin fit parameters and microleakage showed no strong correlations; cast crowns cemented with RMGI and RC had lower microleakage scores than ZP cement.

  17. Effects of Added Salts on Surface Tension and Aggregation of Crown Ether Surfactants.

    Science.gov (United States)

    Suzuki, Maki; Fujio, Katsuhiko

    2016-01-01

    Two crown ether surfactants, dodecanoyloxymethyl- (C11Φ6) and octanoyloxymethyl-18-crown-6 (C7Φ6), were synthesized and the surface tension dependence on surfactant concentration of their aqueous solutions was measured both in the absence and presence of alkali chlorides to confirm the critical micelle concentration (CMC) is highest for the added cation that have an ionic diameter comparable to the hole size of the crown ether ring and that several break points on the surface tension vs. concentration curves occur for these crown ether surfactants. For C11Φ6 and C7Φ6, in the absence of salt, the surface tension vs. concentration curves had two break points. Using the solubilization of a water-insoluble dye as an indicator, we found that the break point at the higher concentration (m0) for C7Φ6 was due to micelle formation. Two break points were also observed for the aqueous solution of C11Φ6 in the presence of NaCl, KCl, RbCl, and CsCl salts at concentrations of 0.22 mol kg(-1) and for C7Φ6 with 0.22 mol kg(-1) KCl added. The CMC (m0) was found to be the highest for solutions containing K(+) salts because K(+) has an ionic diameter comparable to the hole size of 18-crown-6 ring. Furthermore, the CMC decreased as the ionic diameters of the added cations deviated from the hole size. The molecular areas at two break points, estimated by the Gibbs adsorption isotherm, except for that at the break point at mI of C7Φ6, were very small for an adsorbed monolayer. Further investigation is required to elucidate the reason for the break point at mI. PMID:26666275

  18. INTERPOLATION WITH RESTRICTED ARC LENGTH

    Institute of Scientific and Technical Information of China (English)

    Petar Petrov

    2003-01-01

    For given data (ti,yi), I= 0,1,…,n,0 = t0 <t1 <…<tn = 1we study constrained interpolation problem of Favard type inf{‖f"‖∞|f∈W2∞[0,1],f(ti)=yi,i=0,…,n,l(f;[0,1])≤l0}, wherel(f";[0,1])=∫1 0 / 1+f'2(x)dx is the arc length off in [0,1]. We prove the existence of a solution f* of the above problem, that is a quadratic spline with a second derivative f"* , which coincides with one of the constants - ‖f"*‖∞,0,‖f"*‖∞ between every two consecutive knots. Thus, we extend a result ofKarlin concerning Favard problem, to the case of restricted length interpolation.

  19. Length of a Hanging Cable

    Directory of Open Access Journals (Sweden)

    Eric Costello

    2011-01-01

    Full Text Available The shape of a cable hanging under its own weight and uniform horizontal tension between two power poles is a catenary. The catenary is a curve which has an equation defined by a hyperbolic cosine function and a scaling factor. The scaling factor for power cables hanging under their own weight is equal to the horizontal tension on the cable divided by the weight of the cable. Both of these values are unknown for this problem. Newton's method was used to approximate the scaling factor and the arc length function to determine the length of the cable. A script was written using the Python programming language in order to quickly perform several iterations of Newton's method to get a good approximation for the scaling factor.

  20. Variable focal length deformable mirror

    Science.gov (United States)

    Headley, Daniel; Ramsey, Marc; Schwarz, Jens

    2007-06-12

    A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

  1. Reducing the risk of sensitivity and pulpal complications after the placement of crowns and fixed partial dentures.

    Science.gov (United States)

    Brännström, M

    1996-10-01

    Sensitivity after cementation of a crown with glass-ionomer cement is often attributed to an adverse effect on the pulp by the luting agent. Most permanent restorative materials in common use today do not tend to irritate the pulp; the main cause of pulpal damage is infection, the bacteria originating in the smear layer or deep in the dental tubules, inaccessible to caries-excavating procedures. A poorly fitting provisional crown may expose cut dentin to the oral fluids, and mechanical trauma caused by frictional heat during preparation may also damage the pulp. The following precautions are recommended during precementation procedures to reduce the risk of an inflammatory response in the pulp: (1) The provisional crown should be well fitting, covering cervical dentin but not impinging on the periodontal tissues. The permanent crown should be cemented as soon as possible. (2) The superficial smear layer should be removed and the dentinal surface should be treated with an antibacterial solution before the provisional crown is placed. (3) To decrease dentinal permeability under the provisional crown, the dentinal surface should be covered with a liner that can be easily removed before final cementation. (4) to ensure optimal mircomechanical bonding, the dentinal surface should be thoroughly cleaned, and the dentin should be kept moist until cementation. (5) The occlusion should be carefully checked before cementation of the crown. PMID:9180403

  2. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate.

    Science.gov (United States)

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-01-01

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns. PMID:27023532

  3. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    Raphael Pilo

    2016-03-01

    Full Text Available The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC or Self Adhesive Resin Cement (SARC. Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa were significantly higher than those for SARC (2.28 ± 0.58 MPa. The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns.

  4. CRL6, a member of the CHD protein family, is required for crown root development in rice.

    Science.gov (United States)

    Wang, Yihua; Wang, Di; Gan, Ting; Liu, Linglong; Long, Wuhua; Wang, Yunlong; Niu, Mei; Li, Xiaohui; Zheng, Ming; Jiang, Ling; Wan, Jianmin

    2016-08-01

    The root system in monocotyledonous plants is largely composed of postembryonic shoot-borne roots named crown roots, which are important for nutrients and water uptake. The molecular mechanism underlying regulation of crown root development is not fully explored. In this study, we characterized a rice (Oryza sativa) mutant defective in crown root formation, designated as crown rootless6 (crl6). Histological analysis showed that CRL6 influences crown root formation by regulating primordial initiation and development. Map-based cloning and subsequent complementation tests verified that the CRL6 gene encodes a member of the large chromodomain, helicase/ATPase, and DNA-binding domain (CHD) family protein. Realtime RT-PCR analysis showed that CRL6 was most highly expressed in the stem base region where crown roots initiated. In addition, auxin-action inhibited phenotype was observed during crl6 development. The expressions of OsIAA genes were down-regulated in crl6. Our results provide evidence that CRL6 plays an important role in crown root development in rice via auxin-related signaling pathway. PMID:27108205

  5. Comparative evaluation of shear bond strength of conventional composite resin and nanocomposite resin to sandblasted primary anterior stainless steel crown

    Directory of Open Access Journals (Sweden)

    Khatri A

    2007-06-01

    Full Text Available To evaluate and compare the shear bond strength of conventional composite resin and nanocomposite resin to sandblasted primary anterior stainless steel crown. The study samples consisted of 30 primary anterior stainless steel crowns (Unitek TM , size R4, embedded in resin blocks with crown, in test groups of 15 samples each. Mounting of the crown was done using resin block with one crown each. Sandblasting was done and the bonding agent Prime and Bond NT (Dentsply was applied on the labial surface of the primary anterior sandblasted crown. The composite resin and nanocomposite resin were placed into the well of Teflon jig and bonded to Stainless Steel Crowns. The cured samples were placed in distilled water and stored in incubator at 37°C for 48 hours. Shear bond strength was measured using universal testing machine (Hounsefield U.K. Model, with a capacity of 50 KN. Independent sample ′t′ test revealed a nonsignificant ( P < 0.385 difference between mean shear bond strength values of conventional and nanocomposite group. The bond strength values revealed that nanocomposite had slightly higher mean shear bond strength (21.04 ± 0.56 compared to conventional composite (20.78 ± 0.60. It was found that conventional composite resin and nanocomposite resin had statistically similar mean shear bond strength, with nanocomposite having little more strength compared to conventional composite.

  6. Minimal Length, Measurability and Gravity

    Directory of Open Access Journals (Sweden)

    Alexander Shalyt-Margolin

    2016-03-01

    Full Text Available The present work is a continuation of the previous papers written by the author on the subject. In terms of the measurability (or measurable quantities notion introduced in a minimal length theory, first the consideration is given to a quantum theory in the momentum representation. The same terms are used to consider the Markov gravity model that here illustrates the general approach to studies of gravity in terms of measurable quantities.

  7. Consequences of crown shortening canine teeth in Greenland sled dogs

    DEFF Research Database (Denmark)

    Kortegaard, H E; Anthony Knudsen, T; Dahl, S;

    2015-01-01

     · 8% in dogs without pulp exposure (n = 133) resulting in a significant (relative risk, 109 · 5; P < 0 · 001) risk of periapical pathology in teeth with pulp exposure compared to teeth without pulp exposure. CLINICAL SIGNIFICANCE: The high risk of periapical pathology observed in teeth with pulp...... exposure confirms that these teeth should not be neglected in affected dogs....

  8. Crown Ether-Metalloporphyrins as Ditopic Receptors and Pyropheophorbide-a Conjugates for the Photodynamic Therapy of Tumors

    OpenAIRE

    Helmreich, Matthias

    2006-01-01

    Starting with motifs obtained in my diploma thesis, the synthesis of the crown ether-porphyrin and the bromomethyl-porphyrin were optimized to obtain both compounds in larger amounts (1-3 g). Complexes of the crown ether-porphyrin with different transition-metals (Zn2+,Co2+/3+, Ni2+, Fe3+, Cd2+) as well as some lanthanoides (Eu3+,Gd3+) were synthesized. The influence of the crown ether on the kinetic stability of the corresponding metalloporphyrins was investigated by the spectroscopic tracin...

  9. Dioxygen Affinities and Biomimetic Catalytic Performance of Transition-metal Complexes with Crowned Bis-Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives were examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.

  10. 全氧化锆嵌体冠在牙合龈距严重不足下颌患牙修复中的应用%Application of zirconia inlay crown in the restoration of mandibular molars with extensively closed occlusogingival distance

    Institute of Scientific and Technical Information of China (English)

    陈婷

    2016-01-01

    Objective To observe effects of zirconia inlay crown in the restoration of mandibular molars with extensively closed occlu-sogingival distance. Methods 21 residual crowns of molars which were hard to restore using common crowns because of their closed occlusogingival distance less than 2mm were treated after root canal therapy with zirconia inlay crowns. Results After a 2-3 year peri-od, the inlay crowns were all maintained well, with good marginal sealing, acceptable gingival index and no porcelain collapse. The restoration of the teeth shape and its function recovery were both satisfactory. Conclusion For the restoration of mandibular molars with extensively closed occlusogingival distance, the zirconia inlay crown is an easy and simple technique to apply, with satisfactory clinical restoration effects.%目的 评价全氧化锆嵌体冠修复牙合龈距严重不足者下颌患牙的疗效.方法 选择下颌后牙牙合龈距小于2 mm,无法行全冠修复的21个病例,根管治疗术后,制作21个全氧化锆嵌体冠进行修复.结果 经2~3年随访观察修复体的边缘密合性、牙龈指数、崩瓷现象等指标,21个修复体使用正常.患者对牙体外形及功能恢复满意.结论 全氧化锆嵌体冠对于治疗下颌牙合龈距严重不足患牙是一种简单、易行、效果良好的修复方法 .

  11. Automated crown detection algorithm: an analysis of two tropical Amazonian forests

    Science.gov (United States)

    Palace, M.; Keller, M.; Asner, G.; Hagen, S.; Braswell, B.

    2002-12-01

    Spatial analysis of crowns in high-resolution images can improve the estimate of carbon stocks on regional and local scales, aid in demographic studies on the stand level, begin to analyze tree structural properties at the landscape level, and aid in forestry efforts. Radiative inverse transfer models, gap models, and cohort models may be parameterized with the spatial analysis of crowns and subsequently derived forest structural characteristics. We developed an algorithm to automatically detect tree crowns in two tropical Amazonian forests. IKONOS panchromatic images were used from two Amazonian forests in Para, Brazil: the Tapajos National Forest, (3.08° S, 54.94° W) and the Fazenda Cauaxi, (3.75° S, 48.37° W). Analysis was conducted on undisturbed forests from both sites. Our method combines local maximum filtering and local minima value finding methods with analysis of extracted transect data from the local maxima. We use a derivative threshold that ends the transect. Once all pixels of a given brightness value are analyzed, an iterative step examines the next lower brightness value. Pixels where crowns have been delineated are taken out of further analysis. Our method allows for overlap of crowns, gaps between crowns, and complex and noisy canopies to be analyzed. A sensitivity analysis was run on the derivative threshold and the minimum local maximum value to seed the transect analysis. Least-squares goodness of fit is conducted to examine parameterization from the sensitivity analysis. The best fit for the derivative threshold is found set at -8. The sensitivity analysis finds that the minimum local maxima is related to the difference between the maximum brightness value and brightness value with the highest frequency. Mean, minimum and maximum crown widths for field data are (mean 9.0 m +/- 1.6 S.D., min 1.0 m, max 40.7 m) and automated estimation are (mean 11.9 m +/- 5.0 S.D., min 2.0 m, max 34.0 m). The Kolmogorov-Smirov test for difference between

  12. 选择性激光熔覆技术与铸造法制作全冠适合性的比较研究%Comoarative adaptation of crowns of selective laser melting and wax-lost-casting method

    Institute of Scientific and Technical Information of China (English)

    李国强; 沈晴昳; 高建华; 邬雪颖; 陈骊; 戴文安

    2012-01-01

    目的 比较选择性激光熔覆技术( selective laser melting,SLM)与铸造法制作的全冠适合性差异,以期为临床提供依据.方法 通过切削技术制作铝合金试件,设计3种试件直径:切牙8.6 mm,前磨牙7.2 mm,磨牙11.2 mm,每种16件.将试件分为SLM组和铸造组,分别制作钴铬合金全冠并用磷酸锌粘接剂粘接.扫描电镜下观察粘接面各测量点粘接剂厚度.结果 SLM组牙冠颈缘、试件下1/3区、轴面角处和(稔)面中央点间隙[分别为(36.51±2.94)、(49.36±3.31)、(56.48±3.35)和(42.20±3.60)μm]小于铸造组相应部位[分别为(68.86±5.41)、(58.86±6.10)、(70.62±5.79)和(69.90±6.00) μm],两组差异均有统计学意义(P<0.05).结论 铸造法和SLM制作的全冠适合性均在临床可接受的范围内,但SLM法更接近美国牙科协会的标准,值得推广应用.%Objective To investigate the marginal adaptation of crowns fabricated by selective laser melting( SLM ) and wax-lost-casting method,so as to provide an experimental basis for clinic.Methods Co-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group.All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine.The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope( SEM ). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically.Results The gap between SLM crowns were (36.51 ±2.94),(49.36 ±3.31 ),( 56.48 ± 3.35 ),( 42.20 ± 3.60) μm,and wax-lost-casting crowns were ( 68.86 ± 5.41 ),( 58.86 ±6.10),(70.62 ±5.79),(69.90 ±6.00) μm.There were significant difference between two groups( P <0.05). Conclusions Co-Cr alloy full crown fabricated by wax-lost-casting method and SLM method provide acceptable marginal adaptation in clinic,and the marginal adaptation of SLM is better than that of wax-lost-casting method.

  13. Evaluation of the Effect of Bonding Silver-amalgam Alloy Post-core Technique for Restoration Residual Molar Crown%黏结银汞桩核磨牙残冠修复临床观察

    Institute of Scientific and Technical Information of China (English)

    王强

    2011-01-01

    目的:观察和评价黏结银汞桩核修复磨牙残冠的临床效果.方法:对50例磨牙残冠进行黏结银汞桩核修复,观察疗效,随访时间12个月.结果:随访检查束发现修复体松动、折裂、脱落,X线牙片显示银汞桩与根管壁之间结合紧密.结论:黏结银汞桩核用于磨牙残冠修复具有明显技术优势,临床应用效果良好.%Objective:To evaluate the clinical effect of bonding silver-amalgam alloy post-core technique in restoration of molar crown.Methods: 50 teeth in 50 cases, apply with bonding silver-amalgam alloy post-core technique.The patients were followed up for 12 months.Results: The effect of bonding silver-amalgam alloy post-core technique for restoration residual molar crown was satisfied Conclusion:Bonding silver-amalgam alloy post-core technique could effectively in restoration residual molar crown.

  14. Effect of axial groove and resin luting cements on the retention of complete cast metal crowns

    Directory of Open Access Journals (Sweden)

    K Rajkumar

    2009-01-01

    Full Text Available Background : The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. Methods: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group. An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05. Results: No significant differences in the tensile stress values were noted between the control (mean: 5.76±0.392 MPa and study (mean: 5.93±0.751 MPa groups cemented with RelyX Unicem. No sig-nificant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa and study (mean: 5.15 ±0.478 MPa groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. Conclusion: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem® yielded greater reten-tion values when compared to Calibra®.

  15. Estimating crown defoliation of Scots pine (Pinus sylvestris L. trees using small format digital aerial images

    Directory of Open Access Journals (Sweden)

    Mozgeris G

    2013-01-01

    Full Text Available This study focuses on the possibilities of using small format digital aerial images for the estimation of tree crown condition. The test area was located in the eastern part of Lithuania where Scots pine (Pinus sylvestris L. trees prevail and was photographed using a Canon EOS-1DsMark II digital camera installed on-board a SkyArrow ultra-light aircraft. The camera lenses were adopted to capture images corresponding to conventional color-infrared photography. In addition, the test area was photographed using a large format digital frame aerial camera (Vexcel UltraCam D installed on board a Rockwell Turbo Commander 690A high performance commuter aircraft. The ground sampling density of the images taken was around 9-10 cm. Crown defoliation was assessed in the field for more than 500 Scots pine trees located in 46 sample plots representing stands of trees that were either 65 years old or 170 years old. Spearman’s correlations coefficients were used to check for relationships between tree crown defoliation and image characteristics. The defoliation was also predicted using the non-parametric k-Nearest Neighbor method applied on data available from aerial images alone. The results were validated using the “Leave One Out” technique by comparing the obtained data with data from the field assessed defoliation rates. The prediction root mean square errors were calculated using data from the small format aerial images as being 11.5% for the younger trees, whereas those calculated using conventional aerial images were between 9.5 and 9.9%. The differences in predicted root mean square errors disappeared in the older stands and both methods produced errors of between 8.1 and 8.5%. Defoliation class was correctly predicted for approximately 84-88% of the older tree crowns and correctly for 75-85% of the younger tree crowns. These results showed that small format aerial images had the potential to predict defoliation in tree crowns and were comparable

  16. Analysis of the dental morphology of Plio-Pleistocene hominids. III. Mandibular premolar crowns.

    Science.gov (United States)

    Wood, B A; Uytterschaut, H

    1987-10-01

    Accurate measurements were made of the overall size of both the crown and its components of 91 mandibular premolar teeth of early hominids. The shape of the crown outline and the fissure pattern, and the expression of four morphological traits, were also recorded. Non-dental criteria were used to allocate the specimens into four major taxonomic categories (EAFROB, EAFHOM, SAFROB and SAFGRA), approximating to the hypodigms of, respectively, A. boisei, H. habilis and Homo sp., A. robustus and A. africanus. Those specimens that could not be so allocated were regarded as 'unknown'. Intertaxonomic overall size differences were established for both the P3 and P4, with the latter showing little overlap in crown size between the three taxonomic categories usually associated with East African sites (i.e. EAFROB, EAFHOM and SAFGRA). Crown shape is a better discriminator between taxonomic groups for P3 than for P4, with the P3s of EAFHOM showing less buccolingual expansion than the other taxonomic categories. Cusp number, the location of the lingual cusp and the expression of the median longitudinal fissure, show systematic variation between the main taxonomic categories, with the 'robust' taxa being distinguished by additional distal cusps, and a more deeply incised median longitudinal fissure, and EAFHOM being peculiar in having a distally situated lingual cusp. Marginal grooves show more overlap in their incidence and expression between taxonomic categories. Both the 'robust' australopithecine taxonomic categories have relatively large talonids, apparently at the expense of the size of the buccal cusp. The relative talonid enlargement was greater for P3 than for P4, a conclusion which is at variance with previous published assessments. Investigation of the allometric relationships between relative talonid size and overall crown size in the pooled 'non-robust' taxonomic categories did not suggest that talonid enlargement was a simple consequence of a larger-size crown. The

  17. Management of horizontal crown fracture caused by traumatic injury with endorestoration treatment

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2011-09-01

    Full Text Available Background: Traumatic injuries of teeth are the main cause of emergency treatment in dental practice. The horizontal crown fracture more frequently observed usually occurs in maxillary anterior region and young male patients. The most common type of coronal fracture is in the middle third, followed by root and apical part. Purpose: The aim of this case report is to present the management of crown fracture of teeth with pulp exposure caused by dental trauma with endorestoration treatment in order to reconstruct the shape and the function of the teeth. Case: A 22 years old male with horizontal crown fracture of anterior teeth. The patient asked for aesthetic dental treatment both for its form and function. Case management: This horizontal crown fracture of anterior teeth with pulp exposure caused by dental trauma still could be reconstructed, mainly by endorestoration treatment. The endodontic treatment with post and core insertion in the root canal then would increase its retention. Later, the porcelain crown would aesthetically recover its original form and function, therefore, it would improve the patient’s confidence and teeth function. Conclusion:  Endorestoration treatment on anterior teeth with harizontal crown fractures and pulp exposure is able to recover the normal function, aesthetic, and self-confidence.Latar belakang: Trauma pada gigi merupakan penyebab utama perawatan darurat dalam praktek dokter gigi. Fraktur mahkota horisontal pada umunya terjadi pada gigi anterior rahang atas dan terjadi pada penderita pria muda. Jenis yang paling sering dari fraktur mahkota adalah pada sepertiga tengah, daerah akar dan apical. Tujuan: Laporan kasus ini menjelaskan penatalaksanaan fraktur mahkota gigi dengan pulpa terbuka akibat trauma dengan perawatan endorestorasi untuk mengembalikan bentuk dan fungsi gigi. Kasus: Penderita pria umur 22 tahun dengan fraktur mahkota horizontal pada gigi anterior. Penderita tersebut menginginkan perawatan

  18. Bayes Estimation of Queue Length

    Czech Academy of Sciences Publication Activity Database

    Dohnal, Pavel

    Praha : ÚTIA AV ČR, 2006 - (Přikryl, J.; Šmídl, V.). s. 47-48 [International PhD Workshop on Interplay of Societal and Technical Decision-Making, Young Generation Viewpoint /7./. 25.09.2006-30.09.2006, Hrubá Skála] R&D Projects: GA AV ČR 1ET100750401; GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : traffic flow * queue length * occupancy * intensity Subject RIV: BC - Control Systems Theory

  19. Bayes Estimation of Queue Length

    Czech Academy of Sciences Publication Activity Database

    Dohnal, Pavel

    Praha : ÚTIA AV ČR, 2006 - ( And rýsek, J.), s. 1-8 [International PhD Workshop on Interplay of Societal and Technical Decision-Making, Young Generation Viewpoint /7./. Hrubá Skála (CZ), 25.09.2006-30.09.2006] R&D Projects: GA MŠk 1M0572; GA AV ČR 1ET100750401 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bayes estimation * queue length * traffic flow * occupancy * intensity Subject RIV: BC - Control Systems Theory

  20. Minimal Length, Measurability and Gravity

    CERN Document Server

    Shalyt-Margolin, A E

    2016-01-01

    The present work is a continuation of the previous papers written by the author on the subject. In terms of the measurability (or measurable quantities) notion introduced in a minimal length theory, first the consideration is given to a quantum theory in the momentum representation. The same terms are used to consider the Markov gravity model that here illustrates the general approach to studies of gravity in terms of measurable quantities. This paper is dedicated to the 75th Anniversary of Professor Vladimir Grigor'evich Baryshevsky.