bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation and Analysis of Wear Reduction in Piston Rings through Coating
Authors: Jayanth P. , Sangeeth Kumar E.
Published: November 2015

In this study, the surface of a Piston Ring in the engine is coated with multilayered coating powder using plasma-spray technique, and its surface behavior is subsequently analyzed. The purpose of this study is to analyze the mechanical and thermal effects of surface coating for a Piston Ring during friction. Here specimens with and without coatings were prepared and then microstructure, hardness and corrosion tests were carried out. From the experimental results and Ansys results, it has been found that the coated specimen has improved the properties in improving the diesel engine performance. The results show less deformation and fewer scratches due to wear on the multilayer coated Piston Ring as compared to the uncoated one. The surfaces topography and the structure of the plasma spray coatings is observed on the scanning Electron microscope. The evaluation of the adhesion of coatings is made using the hardness test and also compared using the thermal barrier properties. Taking into account the results of measurements, one can state that the lowest wear and thermal resistance on piston rings by plasma spray coating.
Mechanical Properties of Multi Axially Forged Hybrid Composite
Authors: Saravana Kumar A. , Sasikumar P.
Published: November 2015

This work investigated the influence of multi axial forging (MAF) on the microstructure and mechanical properties of AA6063/Al2O3/Gr hybrid composite. It reveals that the effectiveness of forged composite exhibited better mechanical properties. The AA6063 reinforced with Al2O3 and 1 wt. % graphite (Gr) hybrid composite were fabricated using stir casting technique. The microstructure of the hybrid composite was examined using optical microscope. The mechanical properties in terms of hardness, flexural strength and compression strength were investigated. It was observed that the mechanical properties of multi axially forged hybrid composite exhibited around 15, 7 and 5 times higher than unreinforced alloy, as-casted hybrid composite and as-hardened hybrid composite. These results revealed that the multi axially forged hybrid composite would be well suited for high strength applications.
Modal Analysis of Annular Plate with Crack and its Effect on Natural Frequency
Authors: Pramod R. , Shashi Kumar M.E. , Mohan Kumar S.
Published: November 2015

The study of the dynamic behavior of annular plates with circumferential cracks can find many applications in several machine components such as flywheels, clutch plates, compact discs etc. A crack on a structural member introduces a local increase of flexibility in that region then; this affects the static and dynamic characteristics. The effects of cracks on the dynamic characteristics of structures, especially on the natural frequencies and modes, were extensively studied. In this study, the natural frequencies of annular plates with circumferential cracks are investigated by using finite element method. The cracks were non-propagating and open. The annular plate with different cracks was subjected to different boundary conditions and final variation in the natural frequency was obtained, which was compared with the theoretical frequency and the change in the natural frequency was studied. The results of this study with improved elements are compared with the theoretical results in the literature. It is observed that the location and the number of cracks have various effects on the natural frequencies related to the vibration modes.
Controlling the Additives in Lubricating Oil to Minimize the Pitting Failure of Gear Teeth
Authors: Kumar Kalathur , Arul S.
Published: November 2015

Literature reported extensive work on the failure of Industrial power transmission systems, during their routine torque transmission, rotary motion etc. During transmission through gear drive the noise, temperature, stresses, vibration etc are important factors to be considered. When one or more of above exceed certain design limits, the drive and its accessories must be examined for the cause and a preventive maintenance is to be followed. The latest research work carried out, in above area is reviewed. The cause of failure and failure analysis is examined. An attempt is made in this paper, to systematically analyze the modes of failures, the reasons for the same, issues and challenges involved, there in, and measures to be taken for addressing them. This analysis is likely to help the researchers to proceed further in analyzing the failure and to suggest means to prevent failure of gear power transmission systems. The major contribution of present work is, to present the common modes of failure of gear teeth in power transmission systems, and measures to be taken to address the same. In general various additives in the lubricating oil help in controlling initiation of pitting. The present work involves controlling one of the additives namely sulphur in the lubricating oil to control pitting. The present work forms an excellent basis for identifying various other parameters affecting the pitting failure of gear teeth in a gear box.
Design and Development of Drainage Inspection and Anti-Clogging Robot
Authors: Prashanth B.N. , Karthik V. , Karthikeyan S. , Raviteja P.
Published: November 2015

Drain cleaning is often considered as a simple task, but it might not be so always. Many industries function smoothly by constantly dumping the waste, toxic chemicals, biodegradable products frequently in the drains, which results in clogging of drains thus preventing the water flow from the pipes. Around 800 men die because of drain cleaning every year in India. Maintaining, cleaning and resolving the issues of drainage systems have been a severe issue in the surrounding environment where, labors are used without any protective measures. Increase in the laborers deaths has been a major concern in cleaning the drainage blockages. Moreover, identifying the blockage within the drainage system is a time consuming and TDS task. Also, the machines available are very expensive. Thus, a system has to be introduced where humans are not insisted for cleaning the drainage blockages and its maintenance. In view of above, present project is aimed at development of a slender and powerful system to inspect the pipe and disintegrate it to clear the blockage in the pipe.
Outcome of tympanic membrane defect repair with fat and tetrachlorodecaoxide
Authors: Abeysundara U. B. , Rajapaksha R. M. M. A , Prasad C. S. , Wickramasinghe N. S. A , Rathnayake R. A. D. I.
Published: November 2015

No abstract availableCeylon Journal of Otolaryngology Vol.4(1) 2015 pp.9-14
A Good Death in Ratnapura : A Qualitative Study
Authors: Perera M. C. , Ramadasa U. , Chandrasiri G. M. L. W. , Thaibudeen M. A. , Kalupahana K. M. S. N
Published: November 2015

Introduction: One of the most important goals of medical care in patients having a life limiting illness is achieving a ‘‘good death’’. To achieve this, components of a good death should be identified.Objectives: To identify the components of a good death in Ratnapura, Sri Lanka.Methodology: A qualitative, prospective serial study was done. The study sample included patients diagnosed as having life limiting illness and being followed up at the ENT, Palliative care and Oncology units at General Hospital Ratnapura.Results: There were 42 participants in the study. Thirty five (83.33%) of the patients had cancer and 7(16.67%) had non cancer life limiting illnesses. The study identified attributes which fall to 15 categories as common components of ‘‘good death’’.Conclusion: The main categories of good death in Ratnapura, Sri Lanka, were having a good family relationship, having a good relationship with medical staff, Not being aware of death, Fighting against the disease, Dying at ones favourite place, Having faith, Maintaining hope, Maintaining dignity, Freedom from Pain, Physical & Psychological symptoms, Not being a burden to others and Maintaining sense of control. Home was considered the best place to die.Ceylon Journal of Otolaryngology Vol.4(1) 2015 pp. 20-25
The fight against tobacco
Authors: Balbi Bruno , Spanevello Antonio
Published: November 2015

Not available
Electronic cigarette: a possible substitute for cigarette dependence
Authors: Caponnetto P. , Russo C. , Bruno C.M. , Alamo A. , Amaradio M.D. , Polosa R.
Published: November 2015

Cigarette smoking is the leading cause of premature mortality in western countries and it is important for smokers to stop as early as possible. Electronic cigarettes are a popular phenomenon of global proportion. Recent uncontrolled studies, reported that a certain number of smokers have quit using electronic cigarettes. This could hint a role for electronic cigarettes to be used for smoking cessation, and therefore merits further evaluation for this purpose. Besides vaporising nicotine to be inhaled, electronic cigarettes may also provide a coping mechanism for conditioned smoking cues by replacing some of the rituals associated with smoking gestures, and for these reasons cigarette could become a tool – if studied more extensively – in the fight against tobacco-related morbidity and mortality.
Third-hand smoke exposure and health hazards in children
Authors: Ferrante G. , Simoni M. , Cibella F. , Ferrara F. , Liotta G. , Malizia V. , Corsello G. , Viegi G. , La Grutta S.
Published: November 2015

Smoking still represents a huge public health problem. Millions of children suffer the detrimental effects of passive smoking. An increasing number of countries have recently issued laws to regulate smoking in public places. Instead, homes remain a site where children are dangerously exposed to environmental tobacco smoke (ETS). The combination of tobacco smoke pollutants which remain in an indoor environment, the so-called ‘third-hand smoke’ (THS), represent a new concept in the field of tobacco control. THS consists of pollutants that remain on surfaces and in dust after tobacco has been smoked, are re-emitted into the gas-phase, or react with other compounds in the environment to form secondary pollutants. Indoor surfaces can represent a hidden reservoir of THS constituents that could be re-emitted long after the cessation of active smoking. Human exposure to THS pollutants has not yet been thoroughly studied. Infants and children are more prone to the risks related to THS exposure than adults because they typically spend more time indoors and have age-specific behaviours that may expose them to potential health hazards from THS. Further investigations are warranted to study the health effects of THS relevant to different exposure pathways and profiles. It would also be very important to evaluate how THS may affect the lung development through the in utero exposure during the pre-natal life. We aimed at reviewing recent findings published about THS, with special reference to the effects on children’s health.
When the chest is clueless, look downstairs
Authors: Attinà D. , Ciccarese F. , Mughetti M. , Rocca A. , Contini P. , Zompatori M.
Published: November 2015

Not available
When nature frowns: A comprehensive impact assessment of the 2012 Babessi floods on people’s livelihoods in rural Cameroon
Authors: Balgah Roland A. , Buchenrieder Gertrud , Mbue Innocent N.
Published: November 2015

Floods are the most common natural disasters worldwide. Much of the growing literature on the impact of floods, especially in developed countries, and to a lesser extent in rural areas of developing countries, concentrates on economic rather than a comprehensive assessment of combined effects on people’s livelihoods. Holistic floods impact assessments are often done long after the shock, raising problems of data reliability following long recall periods, although post-disaster needs assessments when carried out earlier can facilitate appropriate disaster recovery, relief and reconstruction activities. We applied the sustainable livelihoods framework as a comprehensive approach to assess the impacts of the Babessi floods in 2012 on livelihoods in rural (north western region) of Cameroon 6 weeks after the floods. Using a structured questionnaire, data was collected from victims before and after the floods, using recall methods. A matched sample of nonvictims randomly selected from the same village as the victims was used to assess vulnerability to the floods by household type. Floods were found to have serious economic, social, human and food security impacts on victims. Both government and nongovernmental support were jointly crucial for household recovery. Comparatively observed high levels of recovery were attributed to the low loss of human lives. The article concludes with the need for comprehensive approaches to floods impact assessments. The need for combining formal and informal instruments in post-disaster management in rural areas is also emphasised.
Spatio-temporal patterns and movement analysis of pigs from smallholder farms and implications for African swine fever spread, Limpopo province, South Africa
Authors: Fasina Folorunso O. , Mokoele Japhta M. , Spencer B. Tom , Van Leengoed Leo A.M.L. , Bevis Yvette , Booysen Ingrid
Published: November 2015

Infectious and zoonotic disease outbreaks have been linked to increasing volumes of legal and illegal trade. Spatio-temporal and trade network analyses have been used to evaluate the risks associated with these challenges elsewhere, but few details are available for the pig sector in South Africa. Regarding pig diseases, Limpopo province is important as the greater part of the province falls within the African swine fever control area. Emerging small-scale pig farmers in Limpopo perceived pig production as an important means of improving their livelihood and an alternative investment. They engage in trading and marketing their products with a potential risk to animal health, because the preferred markets often facilitate potential longdistance spread and disease dispersal over broad geographic areas. In this study, we explored the interconnectedness of smallholder pig farmers in Limpopo, determined the weaknesses and critical control points, and projected interventions that policy makers can implement to reduce the risks to pig health. The geo-coordinates of surveyed farms were used to draw maps, links and networks. Predictive risks to pigs were determined through the analyses of trade networks, and the relationship to previous outbreaks of African swine fever was postulated. Auction points were identified as high-risk areas for the spread of animal diseases. Veterinary authorities should prioritise focused surveillance and diagnostic efforts in Limpopo. Early disease detection and prompt eradication should be targeted and messages promoting enhanced biosecurity to smallholder farmers are advocated. The system may also benefit from the restructuring of marketing and auction networks. Since geographic factors and networks can rapidly facilitate pig disease dispersal over large areas, a multi-disciplinary approach to understanding the complexities that exist around the animal disease epidemiology becomes mandatory.
Determination of oxytetracycline residues in cattle meat marketed in the Kilosa district, Tanzania
Authors: Kimera Zuhura I. , Mdegela Robinson H. , Mhaiki Consolatha J.N. , Karimuribo Esron D. , Mabiki Faith , Nonga Hezron E. , Mwesongo James
Published: November 2015

Oxytetracycline is used to treat various diseases in cattle. However, its use may be associated with unacceptable residue levels in food. Oxytetracycline residues in tissues from indigenous cattle were determined in a cross-sectional study conducted in the Kilosa district, Tanzania, between November 2012 and April 2013. A total of 60 tissue samples, including muscle, liver and kidney, were collected from slaughterhouses and butchers and analysed for oxytetracycline using high-performance liquid chromatography. Oxytetracycline residues were found in 71.1% of the samples, of which 68.3% were above acceptable regulatory levels. The mean concentration of oxytetracycline across tissues was 3401.1 μg/kg ± 879.3 μg/kg; concentrations in muscle, liver and kidney were 2604.1 μg/kg ± 703.7 μg/kg, 3434.4 μg/kg ± 606.4 μg/kg and 3533.1 μg/kg ± 803.6 μg/kg, respectively. High levels of oxytetracycline residue in meat from indigenous cattle may pose a health threat to consumers in Kilosa. The findings possibly reflect a general lack of implementation of recommended withdrawal periods, ignorance about drug use and lack of extension services. Strict regulation of the use of antimicrobial drugs in the livestock industry and associated testing of animal-derived food sources prior to marketing are required.
Аппроксимация марковской динамики на дуальном объекте к бесконечномерной унитарной группе
Authors: Olshanski Grigorii Iosifovich
Published: November 2015

Ранее А. М. Бородин и автор построили $4$-параметрическое семейство марковских процессов на дуальном объекте к бесконечномерной унитарной группе. Основной новый результат состоит в том, что эти процессы являются пределами скачкообразных процессов на дуальных объектах к растущим компактным унитарным группам.
Об одном критерии полной непрерывности производной Фреше
Authors: Yerzakova Nina Alexandrovna
Published: November 2015

В предлагаемой работе вводятся два новых класса операторов (не обязательно линейных), определяемые с помощью меры некомпактности Хаусдорфа $\chi$: локально сильно $\chi$-уплотняющий оператор в точке и сильно $\chi$-уплотняющий на бесконечности (на сферических прослойках). Введенные классы операторов включают наряду со всеми вполне непрерывными операторами также некоторые операторы, не являющиеся $\chi$-уплотняющими. Доказываются необходимые и достаточные условия полной непрерывности как производной Фреше в точке, так и асимптотической производной, в случае их существования. Обобщается теорема М. А. Красносельского об асимптотических точках бифуркации для вполне непрерывных векторных полей на класс сильно $\chi$-уплотняющий на бесконечности векторных полей.
Модульные когомологии и когомологии Хохшильда некоторых полугрупповых алгебр
Authors: Shirinkalam A , Purabbas A , Amini Massoud
Published: November 2015

Мы изучаем взаимосвязь между модульными когомологиями и когомологиями Хохшильда банаховых алгебр. Мы показываем, что для любого коммутативного банахова $\mathcal{A}$-$\mathfrak{A}$-бимодуля $X$ и любого $k\in\mathbb{N}$ полунормированные пространства $\mathcal{H}^{k}_{\mathfrak{A}}(\mathcal{A},X^*)$ и $\mathcal{H}^k(\mathcal{A}/J,X^*)$, где $J$ - замкнутый идеал специального вида в
$\mathcal{A}$, изоморфны. В качестве примера мы показываем, что если $S$ - инверсная полугруппа
с множеством идемпотентов $E$ и $\ell^1(E)$ действует на $\ell^1(S)$ умножением справа и тривиально
слева, то группа когомологий $\mathcal{H}^1_{\ell^1(E)}(\ell^1(S),\ell^1(G_S)^{(2n+1)})$, где $G_S$
- максимальный групповой гомоморфный образ полугруппы $S$, тривиальна для каждого
$n\in\mathbb{N}$. Кроме того, группа когомологий $\mathcal{H}^2_{\ell^1(E)}(\ell^1(S), \ell^1(G_S)^{(2n+1)})$ является банаховым пространством.
Effect of Instrumentation Techniques, Irrigant Solutions and Artificial accelerated Aging on Fiberglass Post Bond Strength to Intraradicular Dentin
Authors: Soares Carlos Jose , Estrela Carlos , Santana Fernanda Ribeiro , Silva Júlio Almeida , Alencar Ana Helena Gonçalves , Renovato Sara Rodrigues , Lopes Lawrence Gonzaga
Published: November 2015

Objective

To evaluate the effect of instrumentation techniques, irrigant solutions and specimen aging on fiberglass posts bond strength to intraradicular dentine.

Materials and methods

A total of 120 bovine teeth were prepared and randomized into control and experimental groups resulting from three study factors (instrumentation techniques, irrigant solutions, specimen aging). Posts were cemented with RelyX U100. Samples were submitted to push-out test and failure mode was evaluated under a confocal microscope.

Results

In specimens submitted to water artificial aging, nickel-titanium rotary instruments group presented higher bond strength values in apical third irrigated with NaOCl or chlorhexidine. Irrigation with NaOCl resulted in higher bond strength than ozonated water. Artificial aging resulted in significant bond strength increase. Adhesive cement-dentin failure was prevalent in all the groups.

Conclusion

Root canal preparation with NiTi instruments associated with NaOCl irrigation and ethylenediaminetetra acetic acid (EDTA) increased bond strength of fiberglass posts cemented with self-adhesive resin cement to intraradicular dentine. Water artificial aging significantly increased postretention.

Clinical significance

The understanding of factors that may influence the optimal bond between post-cement and cementdentin are essential to the success of endodontically treated tooth restoration.

How to cite this article

Santana FR, Soares CJ, Silva JA, Alencar AHG, Renovato SR, Lopes LG, Estrela C. Effect of Instrumentation Techniques, Irrigant Solutions and Artificial accelerated Aging on Fiberglass Post Bond Strength to Intraradicular Dentin. J Contemp Dent Pract 2015;16(7): 523-530.
Oral Paleomicrobiology: Study of Ancient Oral Microbiome
Authors: Baroudi Kusai , Dagli Rushabh , Dagli Namrata , Tarakji Bassel
Published: November 2015

Background

Paleomicrobiology is a special branch of micropaleontology concerned with the study of bacterial fossils. We have used the term ‘oral paleomicrobiology’, as in this review we have focused on the ancient oral microflora. Recently, dental calculus and dental pulp have been identified as rich sources of ancient microbial DNA. Study of this ancient genetic material opens a new door to the ancient world. This review gives an overview of history of ancient DNA research, various techniques of analyzing ancient DNA in dental calculus and dental pulp, and the implications of the oral paleomicrobiology.

Materials and methods

A comprehensive literature search was performed in the following databases—pubmed, medline and google scholar for studies published before 10 April, 2015. The following keywords were used—‘ancient DNA’, ‘ancient oral flora, ‘oral paleomicrobiology’ and ‘oral microbiome’, ‘16S rRNA sequencing’. To obtain additional data, a manual search was performed using the reference lists of selected articles.

Result

As a result of literature search, 27 articles were found in pubmed, 12 in google scholar and one in medline. Eight more articles were selected from the reference list of selected articles.

Conclusion

The combination of microbiology and paleontology has brought a revolution in the study of human evolution and microbial communities. The naturally well-preserved samples of microbial DNA from dental pulp and microbial colonies trapped in dental calculus are a potential source of microbial genetic material, which will prove invaluable in resolving mysteries of the past. This may be a beginning of a new era of oral paleomicrobiology, which will contribute in our studies about prevention of disease by establishing symbiosis between human beings and their microbiome.

How to cite this article

Dagli N, Dagli R, Baroudi K, Tarakji B. Oral Paleomicrobiology: Study of Ancient Oral Microbiome. J Contemp Dent Pract 2015;16(7):588-594.
Comparative Evaluation of Fracture Resistance and Mode of Failure of Zirconia and Titanium Abutments with Different Diameters
Authors: Ghodsi Safoura , Shabanpour Reza , Mousavi Niloufar , Alikhasi Marzieh
Published: November 2015

Aim

The purpose of the current study was to compare the fracture resistance and mode of failure of zirconia and titanium abutments with different diameters.

Materials and methods

Fourteen groups of abutments including prefabricated zirconia, copy-milled zirconia and titanium abutments of an implant system (XiVE, Dentsply) were prepared in different diameters. An increasing vertical load was applied to each specimen until failure occurred. Fracture resistance was measured in each group using the universal testing machine. Moreover, the failure modes were studied and categorized as abutment screw fracture, connection area fracture, abutment body fracture, abutment body distortion, screw distortion and connection area distortion. Groups were statistically compared using univariate and post-hoc tests. The level of statistical significance was set at 5%.

Results

Fabrication method (p = 0.03) and diameter (p < 0.001) had significant effect on the fracture resistance of abutments. Fracture resistance of abutments with 5.5 mm diameter was higher than other diameters (p < 0.001). The observed modes of failure were dependent on the abutment material as well. All of the prefabricated titanium abutments fractured within the abutment screw. Abutment screw distortion, connection area fracture, and abutment body fracture were the common failure type in other groups.

Conclusion

Diameter had a significant effect on fracture resistance of implant abutments, as abutments with greater diameters were more resistant to static loads. Copy-milled abutments showed lower fracture resistance as compared to other experimental groups.

Clinical significance

Although zirconia abutments have received great popularity among clinicians and even patients selecting them for narrow implants should be with caution.

How to cite this article

Shabanpour R, Mousavi N, Ghodsi S, Alikhasi M. Comparative Evaluation of Fracture Resistance and Mode of Failure of Zirconia and Titanium Abutments with Different Diameters. J Contemp Dent Pract 2015;16(8):613-618.
Antimicrobial Activity and pH of Calcium Hydroxide and Zinc Oxide Nanoparticles Intracanal Medication and Association with Chlorhexidine
Authors: Tanomaru-Filho Mario , Guerreiro-Tanomaru Juliane M , Faria Gisele , Aguiar Alana Souza , Leonardo Renato Toledo
Published: November 2015

Aim

To evaluate pH and antibacterial activity of pastes with calcium hydroxide [Ca(OH)2] and zinc oxide (ZnO) microparticles (micro) or nanoparticles (nano) and association with 0.4% chlorhexidine againstEnterococcus faecalis.

Materials and methods

The following pastes were analyzed: Ca(OH)2/ZnO micro, (2) Ca(OH)2/ZnO nano, (3) Ca(OH)2/ ZnO micro + 0.4% chlorhexidine, (4) Ca(OH)2/ZnO nano + 0.4% chlorhexidine. Antibacterial activity againstE. faecaliswas evaluated by agar diffusion test. The direct contact test on planktonic cells ofE. faecaliswas performed for 30 and 60 seconds. Root canals from bovine teeth were filled with the pastes and pH was evaluated after 1, 7, 14, 21, 30 and 60 days. The data obtained were submitted to the statistical tests analysis of variance (ANOVA) and Tukey or Kruskal-Wallis and Dunn test, with a 5% significance level.

Results

Calcium hydroxide and zinc oxide nano, and the pastes with 0.4% chlorhexidine were more effective in agar diffusion test. In the direct contact test, the pastes with chlorhexidine showed the highest effect after 30 seconds. All pastes eliminatedE. faecalisafter 60 seconds. All pastes promoted an increase in pH. The highest increase in pH was observed with nanoparticle medications after 1 and 7 days (p < 0.05). After this period, the pastes presented similar pH increase.

Conclusion

It was concluded that calcium hydroxide and zinc oxide nanoparticles promoted greater initial alkalinization. The antimicrobial activity of the pastes againstE. faecalisis favored by the association with chlorhexidine.

Clinical significance

Although nanoparticles of calcium hydroxide and zinc oxide promoted antibacterial effect, the activity againstE. faecalisis favored by association with chlorhexidine.

How to cite this article

Aguiar AS, Guerreiro-Tanomaru JM, Faria G, Leonardo RT, Tanomaru-Filho M. Antimicrobial Activity and pH of Calcium Hydroxide and Zinc Oxide Nanoparticles Intracanal Medication and Association with Chlorhexidine. J Contemp Dent Pract 2015;16(8):624-629.
Evaluation of Bone Thickness and Density in the Lower Incisors’ Region in Adults with Different Types of Skeletal Malocclusion using Cone-beam Computed Tomography
Authors: Hajeer Mohammad Y , Al-Masri Maram MN , Ajaj Mowaffak A , Al-Eed Muataz S
Published: November 2015

Objectives

To evaluate the bone thickness and density in the lower incisors’ region in orthodontically untreated adults, and to examine any possible relationship between thickness and density in different skeletal patterns using cone-beam computed tomography (CBCT).

Materials and methods

The CBCT records of 48 patients were obtained from the archive of orthodontic department comprising three groups of malocclusion (class I, II and III) with 16 patients in each group. Using OnDemand 3D®software, sagittal sections were made for each lower incisor. Thicknesses and densities were measured at three levels of the root (cervical, middle and apical regions) from the labial and lingual sides. Accuracy and reliability tests were undertaken to assess the intraobserver reliability and to detect systematic error. Pearson correlation coefficients were calculated and one-way analysis of variance (ANOVA) was employed to detect significant differences among the three groups of skeletal malocclusion.

Results

Apical buccal thickness (ABT) in the four incisors was higher in class II and I patients than in class III patients (p < 0.05). There were significant differences between buccal and lingual surfaces at the apical and middle regions only in class II and III patients. Statistical differences were found between class I and II patients for the cervical buccal density (CBD) and between class II and III patients for apical buccal density (ABD). Relationship between bone thickness and density values ranged from strong at the cervical regions to weak at the apical regions.

Conclusions

Sagittal skeletal patterns affect apical bone thickness and density at buccal surfaces of the four lower incisors’ roots. Alveolar bone thickness and density increased from the cervical to the apical regions.

How to cite this article

Al-Masri MMN, Ajaj MA, Hajeer MY, Al-Eed MS. Evaluation of Bone Thickness and Density in the Lower Incisors’ Region in Adults with Different Types of Skeletal Malocclusion using Cone-beam Computed Tomography. J Contemp Dent Pract 2015;16(8):630-637.
In vivo Evaluation of Proximal Resin Composite Restorations performed using Three Different Matrix Systems
Authors: Tonetto Mateus Rodrigues , Borges Alvaro Henrique , Firoozmand Leily Macedo , Filho Etevaldo Matos Maia , Bandeca Matheus Coelho , Tavarez Rudys Rodolfo De Jesus , Gomes Isabella Azevedo , Mariz Debora Castelo Branco Rios , Kuga Carlos Milton
Published: November 2015

Objective

The aim of this in vivo study was to radiographically evaluate the proximal contour of composite resin restorations performed using different matrix systems.

Materials and methods

Patients with premolars needing class II type resin composite restorations involving the marginal ridge were selected. Thirty premolars were selected and randomly divided into three groups (n = 10 each) to receive restorations using different matrix systems: group 1: metal matrix coupled to a carrier matrix and wood wedge (G1-MMW); group 2: sectioned and precontoured metal matrix and elastic wedge (G2-SME); and group 3: a polyester strip and reflective wedge (G3-PMR). After the restorative procedure, bitewing radiographs were performed and analyzed by three calibrated professionals. The quality of the proximal contact and marginal adaptation of the proximal surfaces was classified as either correct or incorrect (undercontour/overcontour).

Results

The Pearson Chi-square statistical test (α = 5%) revealed a statistically difference between frequencies of correct and incorrect restorations (α2 = 6.787, p < 0.05). The group G2 SME produced a higher frequency of correct proximal contours (90%), while G1-MMW and G3-PMR had a ratio of 40% correct and 60% incorrect contours respectively.

Conclusion

None of the matrix systems was able to prevent the formation of incorrect proximal contours; however, the sectioned and precontoured metal matrix/elastic wedge configuration provided better results as compared to the other groups.

How to cite this article

Gomes IA, Filho EMM, Mariz DCBR, Borges AH, Tonetto MR, Firoozmand LM, Kuga CM, De Jesus RRT, Bandéca MC. In vivo Evaluation of Proximal Resin Composite Restorations performed using Three Different Matrix Systems. J Contemp Dent Pract 2015;16(8):643-647.
An Evaluation of Inter- and Intraobserver Reliability of Conebeam Computed Tomography- and Two Dimensional-based Interpretations of Maxillary Canine Impactions using a Panel of Orthodontically Trained Observers
Authors: Hajeer Mohammad Y , Al-Homsi Hala K
Published: November 2015

Objectives

To assess intra- and interobserver agreement when evaluating maxillary impacted canines using cone beam computed tomography (CBCT) and two-dimensional (2D) images through a panel of orthodontically trained observers.

Materials and methods

An adult skull with permanent dentition was employed to perform 15 simulated maxillary canine impactions. Two sets of 2D and three-dimensional (3D) radiographic images were acquired. A panel of assessors including 11 PhD and MSc postgraduate orthodontic students evaluated maxillary impacted canines using a standard questionnaire with 11 categorical variables. Kappa (K) statistics as well as Krippendorff's alpha (α) coefficients were used for the analysis of reliability.

Results

A high level of intraobserver agreement was found for both the CBCT- and 2D-based interpretations. The 11 observers demonstrated a higher interobserver agreement for the CBCTbased interpretations than that of the 2D-based interpretations (α = 0.68 and 0.38 respectively). The employed 3D classifications canines was found to be reliable among observers on CBCT images for the labiopalatal position (K = 0.87), mesiodistal position, vertical position, labiopalatal inclination and mesiodistal inclination (α = 0.95, 0.83, 0.84 and 0.92 respectively). The 2D-based interpretations were not in agreement among the 11 observers, except for the mesiodistal position (α = 0.88) and mesiodistal inclination (α = 0.88).

Conclusion

The intraobserver agreement was high for both the 2D- and the CBCT-based interpretations. The interobserver agreement for the CBCT-based interpretations was remarkably higher than that of the 2D-based interpretations. The utilized CBCT-based 3D classifications for the location and inclination of maxillary impacted canines were found reliable among observers.

How to cite this article

Al-Homsi HK, Hajeer MY. An Evaluation of Inter- and Intraobserver Reliability of Cone-beam Computed Tomography- and Two Dimensional-based Interpretations of Maxillary Canine Impactions using a Panel of Orthodontically Trained Observers. J Contemp Dent Pract 2015;16(8):648-656.
San Francisco and the Long 60s
Authors: Hill Sarah
Published: November 2015

San Francisco and the Long 60s tells the fascinating story of the legacy of popular music in San Francisco between the years 1965-69. It is also a chronicle of the impact this brief cultural flowering has continued to have in the city – and more widely in American culture – right up to the present day. The aim of San Francisco and the Long 60s is to question the standard historical narrative of the time, situating the local popular music of the 1960s in the city’s contemporary artistic and literary cultures: at once visionary and hallucinatory, experimental and traditional, singular and universal. These qualities defined the aesthetic experience of the local culture in the 1960s, and continue to inform the cultural and social life of the Bay Area even fifty years later.

The brief period 1965-69 marks the emergence of the psychedelic counterculture in the Haight-Ashbury neighbourhood, the development of a local musical ‘sound’ into a mainstream international ‘style’, the mythologizing of the Haight-Ashbury as the destination for ‘seekers’ in the Summer of Love, and the ultimate dispersal of the original hippie community to outlying counties in the greater Bay Area and beyond. San Francisco and the Long 60s charts this period with the references to received historical accounts of the time, the musical, visual and literary communications from the counterculture, and retrospective glances from members of the 1960s Haight community via extensive first-hand interviews.

For more information, read Sarah Hill's blog posts here:

http://blogs.cardiff.ac.uk/musicresearch/2014/05/15/san-francisco-and-the-long-60s

http://blogs.cardiff.ac.uk/musicresearch/2014/08/22/city-scale/

http://blogs.cardiff.ac.uk/musicresearch/2015/07/21/fare-thee-well/
Estimating ground-level PM2.5 in eastern China using aerosol optical depth determined from the GOCI satellite instrument
Authors: Xu J.-W. , Martin R. V. , van Donkelaar A. , Kim J. , Choi M. , Zhang Q. , Geng G. , Liu Y. , Ma Z. , Huang L. , Wang Y. , Chen H. , Che H. , Lin P. , Lin N.
Published: November 2015

Abstract. We determine and interpret fine particulate matter (PM2.5) concentrations in eastern China for January to December 2013 at a horizontal resolution of 6 km from aerosol optical depth (AOD) retrieved from the Korean geostationary ocean color imager (GOCI) satellite instrument. We implement a set of filters to minimize cloud contamination in GOCI AOD. Evaluation of filtered GOCI AOD with AOD from the Aerosol Robotic Network (AERONET) indicates significant agreement with mean fractional bias (MFB) in Beijing of 6.7 % and northern Taiwan of −1.2 %. We use a global chemical transport model (GEOS-Chem) to relate the total column AOD to the near-surface PM2.5. The simulated PM2.5 / AOD ratio exhibits high consistency with ground-based measurements in Taiwan (MFB = −0.52 %) and Beijing (MFB = −8.0 %). We evaluate the satellite-derived PM2.5 versus the ground-level PM2.5 in 2013 measured by the China Environmental Monitoring Center. Significant agreement is found between GOCI-derived PM2.5 and in situ observations in both annual averages (r2 = 0.66, N = 494) and monthly averages (relative RMSE = 18.3 %), indicating GOCI provides valuable data for air quality studies in Northeast Asia. The GEOS-Chem simulated chemical composition of GOCI-derived PM2.5 reveals that secondary inorganics (SO42-, NO3-, NH4+) and organic matter are the most significant components. Biofuel emissions in northern China for heating increase the concentration of organic matter in winter. The population-weighted GOCI-derived PM2.5 over eastern China for 2013 is 53.8 μg m−3, with 400 million residents in regions that exceed the Interim Target-1 of the World Health Organization.
Evaluating sensitivity of silicate mineral dissolution rates to physical weathering using a soil evolution model (SoilGen2.25)
Authors: Opolot E. , Finke P. A.
Published: November 2015

Abstract. Silicate mineral dissolution rates depend on the interaction of a number of factors categorized either as intrinsic (e.g. mineral surface area, mineral composition) or extrinsic (e.g. climate, hydrology, biological factors, physical weathering). Estimating the integrated effect of these factors on the silicate mineral dissolution rates therefore necessitates the use of fully mechanistic soil evolution models. This study applies a mechanistic soil evolution model (SoilGen) to explore the sensitivity of silicate mineral dissolution rates to the integrated effect of other soil-forming processes and factors. The SoilGen soil evolution model is a 1-D model developed to simulate the time-depth evolution of soil properties as a function of various soil-forming processes (e.g. water, heat and solute transport, chemical and physical weathering, clay migration, nutrient cycling, and bioturbation) driven by soil-forming factors (i.e., climate, organisms, relief, parent material). Results from this study show that although soil solution chemistry (pH) plays a dominant role in determining the silicate mineral dissolution rates, all processes that directly or indirectly influence the soil solution composition play an equally important role in driving silicate mineral dissolution rates. Model results demonstrated a decrease of silicate mineral dissolution rates with time, an obvious effect of texture and an indirect but substantial effect of physical weathering on silicate mineral dissolution rates. Results further indicated that clay migration and plant nutrient recycling processes influence the pH and thus the silicate mineral dissolution rates. Our silicate mineral dissolution rates results fall between field and laboratory rates but were rather high and more close to the laboratory rates possibly due to the assumption of far from equilibrium reaction used in our dissolution rate mechanism. There is therefore a need to include secondary mineral precipitation mechanism in our formulation. In addition, there is a need for a more detailed study that is specific to field sites with detailed measurements of silicate mineral dissolution rates, climate, hydrology, and mineralogy to enable the calibration and validation of the model. Nevertheless, this study is another important step to demonstrate the critical need to couple different soil-forming processes with chemical weathering in order to explain differences observed between laboratory and field measured silicate mineral dissolution rates.
Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon
Authors: Zhou L. , Tan Y. , Huang L. , Hu Z. , Ke Z.
Published: November 2015

Abstract. To examine seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in oligotrophic tropical waters under the influence of seasonal reversing monsoon, dilution experiments were conducted during the summer of 2009 (21 May to 9 June) and winter 2010 (9 to 18 November) in the southern South China Sea (SSCS). The results showed that environmental variables, phytoplankton biomass, phytoplankton growth rate (μ), microzooplankton grazing rate (m), and correlationship (coupling) between the μ and m, rather than the microzooplankton grazing impact on phytoplankton (m/μ) significantly varied between the two seasons. Higher relative preference index (RPI) for the larger-sized (> 3 μm) phytoplankton than pico-phytoplankton (< 3 μm), indicating significant size-selective grazing by microzooplankton on the larger-sized phytoplankton, were also observed. The μ and m were significantly correlated with seawater salinity and temperature, and phytoplankton biomass, which indicated that salient seasonal variations in the phytoplankton growth and microzooplankton grazing in the SSCS were closely related to the environmental variables under the influence of the East Asian monsoon. We propose that intermittent arrivals of the northeast winter monsoon could lead to the low μ and m, and the decoupling between the μ and m in the SSCS, through influencing nutrient supply to the surface water, and inducing surface seawater salinity decrease. The low m/μ (< 50 % on average) indicates low remineralization of organic matter mediated by microzooplankton and mismatch between the μ and m, and thus probably accounts for part of the high vertical biogenic particle fluxes in the prevailing periods of the monsoons in the SSCS. The size-selective grazing suggests that microzooplankton grazing partially contributes to the pico-phytoplankton dominance in the oligotrophic tropical waters such as that of the SSCS.
Key biogeochemical factors affecting soil carbon storage in Posidonia meadows
Authors: Serrano O. , Ricart A. M. , Lavery P. S. , Mateo M. A. , Arias-Ortiz A. , Masque P. , Steven A. , Duarte C. M.
Published: November 2015

Abstract. Biotic and abiotic factors influence the accumulation of organic carbon (Corg) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2–4 m depth) accumulated 3 to 4-fold higher Corg stocks (averaging 6.3 kg Corg m−2) at 3 to 4-fold higher rates (12.8 g Corg m−2 yr−1) compared to meadows closer to the deep limits of distribution (at 6–8 m depth; 1.8 kg Corg m−2 and 3.6 g Corg m−2 yr−1). In shallower meadows, Corg stores were mostly derived from seagrass detritus (88 % in average) compared to meadows closer to the deep limit of distribution (45 % on average). Also, sediment accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr−1 and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr−1 and 5 %, respectively). The Corg stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg Corg m−2 and 1.2 g Corg m−2 yr−1) were 3 to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8 and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypotheses that Corg storage in seagrass soils is influenced by interactions of biological (e.g. meadow productivity, cover and density), chemical (e.g. recalcitrance of Corg stocks) and physical (e.g. hydrodynamic energy and sediment accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.
N2 fixation in eddies of the eastern tropical South Pacific Ocean
Authors: Löscher C. R. , Bourbonnais A. , Dekaezemacker J. , Charoenpong C. N. , Altabet M. A. , Bange H. W. , Czeschel R. , Hoffmann C. , Schmitz R. A.
Published: November 2015

Abstract. Mesoscale eddies play a major role in controlling ocean biogeochemistry. By impacting nutrient availability and water column ventilation, they are of critical importance for oceanic primary production. In the eastern tropical South Pacific Ocean off Peru, where a large and persistent oxygen deficient zone is present, mesoscale processes have been reported to occur frequently. However, investigations on their biological activity are mostly based on model simulations, and direct measurements of carbon and dinitrogen (N2) fixation are scarce. We examined an open ocean cyclonic eddy and two anticyclonic mode water eddies: a coastal one and an open ocean one in the waters off Peru along a section at 16° S in austral summer 2012. Molecular data and bioassay incubations point towards a difference between the active diazotrophic communities present in the cyclonic eddy and the anticyclonic mode water eddies. In the cyclonic eddy, highest rates of N2 fixation were measured in surface waters but no N2 fixation signal was detected at intermediate water depths. In contrast, both anticyclonic mode water eddies showed pronounced maxima in N2 fixation below the euphotic zone as evidenced by rate measurements and geochemical data. N2 fixation and carbon (C) fixation were higher in the young coastal mode water eddy compared to the older offshore mode water eddy. A co-occurrence between N2 fixation and biogenic N2, an indicator for N loss, indicated a link between N loss and N2 fixation in the mode water eddies, which was not observed for the cyclonic eddy. The comparison of two consecutive surveys of the coastal mode water eddy in November and December 2012 revealed also a reduction of N2 and C fixation at intermediate depths along with a reduction in chlorophyll by half, mirroring an aging effect in this eddy. Our data indicate an important role for anticyclonic mode water eddies in stimulating N2 fixation and thus supplying N offshore.