bluuebunny/crossref_metadata_2025 huggingface dataset:
The Modelling of Crater Wear in Cutting with TiN Coated High Speed Steel Tool
Authors: Pálmai Zoltán
Published: February 2015

The flow zone of the chip in contact with the tool reaches a high temperature in cutting. According to chip hardening experiments α-γ transformation may occur in steel, so the tool is in contact with a high-temperature γ phase at high pressure. The microscopic examination of worn surfaces showed that the degradation of the tool is the result of adhesive/abrasive and thermally activated processes, therefore both friction length and temperature must be taken into consideration in the modelling of crater wear. Wear rate can be described by a non-linear autonomous equation. TiN coating, which increases tool life in high speed steel, changes and slows down the wear of the tool. The activation energy of wear can be calculated from the constants of the wear equation determined by cutting experiments. The deoxidation products to be found in the workpiece in cutting may form a protective layer on the TiN layer that blocks or slows down wear.
The Effect of the Severe Plastic Deformation on the Artificial Aging of the AlMgSi1 Alloy
Authors: Pázmán Judit , Bereczki Péter , Verő Balázs , Kardos Ibolya , Fehér Jánosné
Published: February 2015

The AlMgSi1 alloy is generally used in automotive industry owing to its excellent mechanical properties, which can be further improved by applying severe plastic deformation and heat treatment. The dislocation density in the material increases significantly during severe plastic deformation due to the characteristic intensive shear strain. Therefore the motion of dislocations becomes more and more retarded, consequently the strength improves. In addition, the motion of dislocations can be prevented by aging due to formation of coherent precipitations in the metal matrix in order to realize further increasing in strength. In this paper the combined effect of severe plastic deformation and artificial aging treatment on the evolution of mechanical properties was investigated. The samples were subjected to multiple forging (MF) process at room and enhanced temperature. One part of the deformed samples were heat treated at 150°C for different times. The deformed as well as deformed and heat treated samples were investigated by micro hardness testing and X-ray profile analysis.
Surface Layers Produced by Modified Floe Ferritic Nitrocarburising
Authors: Biro Andrea Szilagyine , Szabo Endre , Tisza Miklos
Published: February 2015

Ferritic nitrocarburising is a surface alloying heat treatment, which can provide to components high surface hardness, thus improved wear resistance. In structural steels the porosity of white layer has a key role in wear resistance: the porosity is undesirable. For tool steels the absence of white layer is undesirable. Floe process is one way to decrease the porosity of white layer. During our experiments we applied a modified Floe process on two different steels. The acontol of this process is simpler than conventional process. We measured the micro-hardness as a function of depth from the surface, and we made microscopic examination to analyse the structure of nitrided layer.
In Situ Optical Microscopic Examination Techniques of Thermally Induced Displacive Transformations
Authors: Benke Márton , Mertinger Valéria
Published: February 2015

The mechanical (reversible deformation, stress-strain diagrams, etc.) and thermal (transformation temperatures, hysteresis) characteristics of the thermoelastic martensitic transformations are in the focus of many manuscripts, however, other aspects of the transformations are given less attention. The relief formation accompanied with displacive transformations ensures the possibility of the direct observation of the mechanism and physical metallurgical characteristics of the martensite↔austenite transformations. The authors of the present manuscript applied the in situ optical microscopy method successfully using self-developed examination techniques and self-made heating stages to characterize the thermally induced displacive transformations in shape memory alloys (SMAs) and TWIP steels.
Effect of High Energy Ar-Ion Milling on Surface of Quenched Low-Carbon Low-Alloyed Steel
Authors: Berecz Tibor , Kalácska Szilvia , Varga Gábor , Dankházi Zoltán , Havancsák Károly
Published: February 2015

Surface preparation for electron backscatter diffraction (EBSD) measurements requires a lot of time and experience. We chose a lath martensitic iron based alloy to demonstrate the efficiency of ion polishing techniques. The average image quality (IQ) values from the EBSD measurements were assigned to be the characteristic parameter for surface goodness. The ideal ion sputtering time and the angle of incidence were determined, and the corresponding inverse pole figure (IPF) and IQ maps were compared to the mechanical polishing treatment.
Welding Properties and Fatigue Resistance of S690QL High Strength Steels
Authors: Dobosy Ádám , Lukács János
Published: February 2015

The objective of this article is to present the first results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed on RUUKKI OPTIM S690QL quenched and tempered high strength steel. In parallel these; welded joints were made on the same steel using gas metal arc welding (GMAW, MIG/MAG) to preparation of the cyclic investigations of the welded joints. In the article, the performance of the welding experiments will be presented; along with the results of the HCF tests executed on the base material and its welded joints. Furthermore, our results will be compared with different literary data.
Examination of Thermodynamic Realignments of Metals and Metal-Alloys, by DMTA Technique
Authors: Gábor Béres , Dugár Zsolt , Kis Dávid , Hansághy Pál
Published: February 2015

The researcher work pushes the borders of the application of a high efficiency equipment, in the matter of metals. With this equipment, which already testified in the compound industry, a flasher query of some metal-related technological parameters could be easily available. Towards the searching, we shaped different compound copper-alloy samples, in different states, and accordingly we monitored the realignments. Following the shaping, the DMTA detected such microscopic transformations (as we expected), according to heating rate, whereby we could determine the specialities of the transformations. In order to monitor the effect of the work hardening, we applied two different shaping grade: 50% and 75%. The heat treatment already took place in the DMTA, using 3 K/min heating rate. The specimens were loaded by inflection in the 2-point bending support with constant frequency and amplitude.Our current object was the monitoring of the recrystallization, and the investigation of the influential factors of this process, but other transitions were also regarded. Those measurements’ results, that the DMTA presented, had been compared with DSC and hardness analysis, whereby we try to conclude to the utility of DMTA, in matter of metal alloys.
Mechanical Properties of Iron Hollow Sphere Reinforced Metal Matrix Syntactic Foams
Authors: Bálint Attila , Szlancsik Attila
Published: February 2015

Metal matrix syntactic foams (MMSFs) were produced by low-pressure inert gas infiltration technique. Matrixes of the produced syntactic foams were Al99.5, AlSi12, AlMgSi1 and AlCu5 respectively, and each was reinforced by pure Fe based hollow. The produced blocks were investigated by optical and scanning electron microscopy. The microstructural investigations revealed proper infiltration with small amount of unwanted voids and an effective and thin interface layer between the matrix materials and the reinforcing spheres. The produced MMSFs were also tested under quasi-static compression loading to get characteristic mechanical properties. The test results showed that the MMSFs with iron spheres have outstanding mechanical properties compared to ‘conventional’ foams.
Examination of the Surface Phosphorus Content of Anodized Medical Grade Titanium Samples
Authors: Katona Bálint , Dobos Gábor , Kiss Gábor
Published: February 2015

In case of titanium dental implants, the main goal is to create a surface where the bone cells can attach well, therefore osseointegration can occur. The chemical composition of the surface has an important role, because the surface has a direct contact with the living tissue and induces different reactions for example peri implantitis or osseointegration. In our work titanium sample made from the most commonly used dental implant material (Ti Grade 5) were investigated. The samples were treated by chemical etching in hydrogen-chloride and in phosphoric acid to remove the cut generated burr. After that the samples were anodized in phosphoric acid solution at 10 V, 20 V, 30 V or 40 V. As a result of these treatments, titanium-dioxide layers were created on the surfaces. Phosphorus (originating from the phosphoric acid bath) may also be found on the surfaces. This may promote osseointegration. The surface compositions were investigated with the aid of Secondary Ion Mass Spectrometry (SIMS). Based on these results we can conclude that anodization in phosphoric acid solution increases the phosphorus content of the surface. Approximately to the middle of the titanium-dioxide layer the phosphorus content is constant but lower with one order of magnitude than on the surface. In the deeper layers the phosphorus content continues to decrease until the base material where it significantly reduce.
Determination of the Guidewire’s Visibility
Authors: Pelyhe Liza , Bognár Eszter
Published: February 2015

The purpose of our research was the development of a new algorithm to the objective quantification of guidewire’s visibility; which is suitable for the classification and comparison of different guidewires, according to this property. The guidewire is a flexible medical device, over which the catheter or the dilator is lead into the vascular system to assist the insertion and position of these devices. During the insertion and the removal of guidewire the movement of distal end is monitored under fluoroscopy. At the beginning of our experiments two algorithms were developed and applied: the first one investigated the total distal end, while the second one investigated two parts of the distal end. Both algorithms were tested on ten guidewires made of same brand and material, so their relative visibility (the visibility of guidewire’s investigated part compared the background) were determined by both method. The average relative visibility was 19.8%±3.0% in case of algorithm for total distal end, and it was 21.5%±2.9% in case of algorithm for two part of distal end. The coefficient of variation was calculated in case of both algorithms, thus characterized by their reliability. Both coefficient of variation were low (0.15 and 0.13), so the algorithms were considered to be reliable. The two algorithm were no significant different (p=0.15), therefore the investigation of the total distal end might be replaced by the investigation of two parts.
Estimation of Thermal Boundary Conditions by Using Hybrid Inverse Approach
Authors: Felde Imre
Published: February 2015

The estimation of thermal boundary conditions occurring during heat treatment processes is an essential requirement for characterization of heat transfer phenomena. In this work, the performance of five optimization techniques is studied. These models are the Conjugate Gradient Method, the Levenberg-Marquardt Method, the Simplex method, the NSGA II algorithm and a hybrid approach based on the NSGA II and Levenberg-Marquardt Method sequence. The models are used to estimate the heat transfer coefficient in 2D axis symmetrical case during transient heat transfer. The performance of the optimization methods is demonstrated using numerical experiments.
Practical Aspects of Micromechanics Based Simulation of Polymer Matrix Composites
Authors: Major Zoltan , Reiter Martin , Jerabek Michael
Published: February 2015

As particle filled and fiber reinforced polymer matrix composites are frequently used in many demanding industrial applications, the proper prediction of the deformation behavior of these materials is of high practical importance for a reliable product design. To predict the thermo-mechanical behavior, micromechanics based simulations were performed using both the mean field homogenization methods (MFH) and full-scale finite element (FS-FE simulations on a material specific representative volume. The applicability and limitations of both methods are introduced based on five different practical examples. Both thermoplastic polymers and elastomers were used as matrix materials with combination of fillers made from different materials having different aspect ratio and revealing a wide variation of alignments and arrangements. While conventionally the behavior of composites revealing processing induced microstructure is predicted for practical engineering applications, novel artificial micro-structures revealing special functionalities might also be designed and their behavior predicted for supporting material development efforts.
Application of 2D-3D Surface Geometrical Features in Tribological Analysis of Ceramics and Ceramic Layers
Authors: Maros Zsolt , Felhő Csaba , Vass Zoltán , Maros Mária B.
Published: February 2015

Microgeometrical characteristics of the surface of engineering components operating in wear condition are important features influencing the wear process of the tribological system. Beside the widely used common 2D roughness parameters – e.g. the Ra, arithmetical mean roughness, Rz, ten point mean roughness, or Rmr, material ratio, etc. – the 3D roughness features (Sa, Sz Smr) provide potentially new means for geometrical description of the operating surfaces. Our paper aims at contributing an overview on the available 2D and 3D features, giving their definition and their potential use in multi-scale characterization of components used especially in wear type loading conditions. An interesting question is the relationship between the 2D and 3D roughness parameters and their information content, relating to tribological problems. Besides giving a systematic overview of the most important parameters applicable in wear analyses we also present examples of 2D and 3D roughness data determined on surface of nitrocarburised steels, as well as silicon nitride ceramics. A special emphasis is placed on those parameters which can be most efficiently used during wear damage analyses of ceramic materials.
On the Topological Characterization of Fullerene-Like Materials Using Zagreb Indices-Based Topological Descriptors
Authors: Réti Tamás , László István , Hamzeh Asma
Published: February 2015

To classify quantitatively the topological structure of all carbon fullerene molecules (fullerene graphs) we suggest a novel two-step method based on the following concept: As a first step, the duals of the fullerene graphs are generated, and as a second step, by using two molecular descriptors called Zagreb indices, we construct appropriately defined topological indices for structural characterization of fullerene isomers. Performing comparative tests on the set of C40 fullerene isomers, it will be demonstrated that the method suggested can be efficiently applicable to the stability prediction of fullerene-like materials.
The Examination of the Cutting Capacity of Different Aluminium Alloys with Statistical Methods, Using Different Edge Material Non-Conventional (Wiper) Edge Geometry Diamond Tools
Authors: Horváth Richárd , Mátyási Gyula , Drégelyi-Kiss Ágota
Published: February 2015

The aluminium alloys are used by the automotive, aerospace industries increasingly because of their numerous advantageous mechanical and chemical properties. Surface roughness measurements are essential in characterization of the features of a machined surface. The most widespread aluminium alloy used in cutting is the die-cast type, alloyed with silicon. Industries prefer using two types of such alloys, the so-called eutectic and hypereutectic alloys reinforced with silicon. In this article the cutting capacities of two die-cast aluminium alloys are examined. The cutting experiments were carried out with design of experiment – DOE (the so-called central composite design – CCD). In the course of the examination three factors were altered (cutting speed – vc, m/min; feed – f, mm; depth of cut – a, mm), and the main surface roughness parameters used in the industries were taken as output parameters. The parameters of the manufactured surface roughness and their deviation in case of different workpiece-materials, tool-materials and edge-materials were analysed with statistical methods. Besides minimizing surface roughness, another important criterion of the manufacturing system (machine – tools – chuck – workpiece) is its surface roughness maintaining capacity, which was analyzed with coefficient of variation (CV).
Ceramic Reinforced Metal Matrix Nano and Micro-Composite Layers Produced by Combined Laser Melt Injection Technology and Thermochemical Surface Treatment
Authors: Janó Viktória
Published: February 2015

In-situ synthesized Nb (C,N) reinforced metal-ceramic composite layers were fabricated on nitridable (16MnCr5) and non-nitridable (S235J) steel surface by combined laser melt injection technology and ferritic nitrocarburizing treatment. The feasibility of processing composites layer by an in situ reaction using laser beam were carried out. Beside that the hardness of the treated layers increases up to 1000-1170 HV0.5 in the diffusion zone and after it the hardness of the samples reach 300-450 HV0.5, which is related the Nb alloying depth (1200-1400 μm). The results of the composite layer are presented in this paper.
Degradation Behaviour of Zeolite Filled Polyurethanes under In Vitro Aging Process
Authors: Kaali Peter , Czél György
Published: February 2015

In this study the degradation and ion/zeolite release processes of in vitro aged zeolite loaded polyurethane composites were evaluated. Two in vitro artificial aging solutions were used; artificial lysosomal fluid (ALF) and Gamble ́s solution and the total exposure time was 12 weeks. Periodically, SEM micrographs were taken of the surface of polyester type polyurethane-zeolite composites. After exposure to ALF solution the samples showed round holes and a rougher surface in general over time. Micrographs of the samples immersed in Gamble’s solution exhibited different signs of degradation with damage features on the surfaces, understood as black holes and a rougher surface pattern. In addition varying amount of salt was also observed on the surfaces that might influence the ion/zeolite release. Furthermore, the zeolite filler caused remarkable changes in mechanical properties after the aging process, which could not be discerned.
N-Alkyl Pyrrolidones for Plasticizing Polyurethane Elastomers
Authors: Bánhegyi András , Vilaboy José Trujillo , Marossy Kálmán
Published: February 2015

Polyurethane (PU) products produced from the reaction of isocyanates and polyols have one of the most extensive consumption of plastics. After the invention in 1937 PU had to wait until the 50’s to spread worldwide and since then their development have been continuous. In PU systems are used varied additives, including plasticizers, which are use by several large companies.In our work a new class of plasticizers, namely N-alkyl-pyrrolidones were used in polyurethane systems. Their trade names are Flexidone® 100, Flexidone® 300 and Flexidone® 500 containing 8, 12 and 18 C-atom long alkyl chain, respectively. These plasticizers showed excellent results in our previous works and the literature has also confirmed their great properties. We supposed that this chemical structure can form a strong interaction with the urethane group.The effect was monitored by hardness and dynamic mechanical (DMA) measurements. Migration and thermally stimulated discharge (TSD) measurments are in progress.
Development of Ceramic Feedstock for Powder Injection Molding
Authors: Karácsony Zs. , Erős A. , Andersen E. , Bánhegyi Gy.
Published: February 2015

As part of our technology development program we started to prepare for introducing ceramic injection molding technology. The technology consists of the following steps: 1. feedstock preparation (mixing the ceramic powder with binding agent), 2. injection molding (green body production), 3. thermal or solvent debinding (brown body production), 4. sintering of the brown body. To make alumina ceramic parts essential to know the properties of all raw materials which are used during the PIM process. That is why this article is focused on the thermogravimetric studies of potential raw materials. These thermogravimetric studies helped to optimize the debinding experiments at specimens with high alumina content. First of all the measured curves of the feedstock were compared with calculated curves from the single raw materials. This comparison helped us to understand the processes in the feedstock during the sintering. Then thermogravimetric experiments in air atmosphere were made to optimize the sintering process. These experiments resulted good structural properties at the sintered parts.
Smartphones in remote medicine and daily neurosurgery: The Sabah update
Authors: Perumall Vinodh , Sellamuthu Pulivendhan , Harun Rahmat , Zenian Mohd
Published: February 2015

Introduction: Healthcare costs continue to rise every day as the demand outgrows the supply of surgeons. The application of telephone consultation for immediate management is needed as most neurosurgeons are technology orientated. This enables a specialist at a remote mobile site to receive the necessary information and reduce transmission time, from the second the patient is seen till the management is obtained. Materials and Methods: We conducted a survey on smartphone ownership among doctors and gathered cases that needed neurosurgical input from 1 st November 2012 till 30 th April 2013 from all 24 district hospitals in Sabah, Malaysia. Results: The percentage of smartphone ownership among doctors surveyed and usage of it for remote and daily medicine at various departments at Queen Elizabeth Hospital, Kota Kinabalu, which shows at least 90% smartphone ownership and proves 100% ownership of cross-platform instant messaging applications and its usage for remote and daily medicine. It also proves to be a more popular mode of referral compared to "teleconsultation" (TC). Discussion: In Sabah, the TC service is used for remote medical consultation and only available at four hospitals. The sender needs direct access to a computer with the TC software, and it causes delay whereas doctors using smartphones will just need to discuss the case on the spot and obtain the appropriate management within minutes. Smartphone usage is also important in daily neurosurgery especially at the department level to promote efficient communication, organization, and interaction between all the staff. As for the department's administrative sector, it is useful to notify if anyone is on leave, attending courses or even meetings as the shortage can be avoided, and redistribution easily done. It also allows us to transfer simple intra-departmental data at any time, and any place whenever required. Conclusion: With all the given fact, it is clear that a day without utilizing this service in our daily life will leave us handicapped and struggling with time and resources.
Early clinical and radiographical results of keel-less and shallow keel cervical disc replacement
Authors: Ling Ji , Tiruchelvarayan Rajendra
Published: February 2015

Background: Cervical disc replacements has been shown to be as effective as fusions in the treatment of radiculopathy or myelopathy due to disc prolapse. Newer implants were designed to reduce the difficulty of end-plate preparation. Since 2010, the authors have started using Discocerv (Alphatec Spine, Carlsbad, USA) a keel-less implant and Activ-C (B. Braun, Sheffield, UK), a shallow keel implant. Aim: The aim of this study was to compare the duration of surgery between cervical disc replacement and anterior cervical discectomy and fusion, and also to evaluate the functional outcome, complications, and radiographic outcome of cervical disc replacement. Results: Fifty patients were included (20 disc replacement and 30 fusion). This was a single surgeon retrospective study, with all surgery performed by the senior author (RT). The mean operation duration for single-level disc replacement was 2.6 h, and for single-level fusion was 2.4 h (P = 0.4684). For 2-levels surgery, the result was 3.5 h for 2-level hybrid surgery (one level disc replacement and one level fusion) and 3.4 h for fusion (P = 0.4489). Disc replacement resulted in preservation of an average of 67% of the angle of motion at the sagittal plane (FFflexion-extension). The average range of motion after disc replacement was 6.1°. The median clinical follow-up duration was 2 years (average 1.8 years). There was no incidence of major complications or significant neurovascular injury in this series of patients. A significant improvement in short form-36 scores was seen as early as 3 months postoperative (from 58 preoperative to 92 at 3 months). The improvement was sustained up to the fourth year of follow-up. Conclusion: Cervical arthroplasty with keel-less and shallow keel implants are safe and relatively easy to perform. The surgical time for disc replacement is not significantly longer than standard fusion surgery. There is reasonably good preservation of motion. The short-term functional improvement is good, and we await further long-term outcome results. The authors felt that cervical disc replacement will have an important role in the treatment of cervical degenerative disc disease in the future.
Endoscopic endonasal trans-sphenoid management of craniopharyngiomas
Authors: Yadav Yad , Nishtha Yadav , Vijay Parihar , Shailendra Ratre , Yatin Kher
Published: February 2015

Introduction: Craniopharyngiomas treatment has been challenging because of their anatomical location. The endoscopic endonasal (EE) trans-sphenoidal approach is indicated in sellar, supra sellar, selected intraventricular lesions in adults and children. We are reporting our initial experience of 44 patients managed by EE approach. Materials and Methods: This is a retrospective study of 44 craniopharyngiomas. The goal of surgery was gross-total resection in all cases. All patients underwent pre- and post-operative comprehensive ophthalmological and endocrinological evaluation. Lumbar drain at the start of the operation was used in all cases with tumor larger than 3 cm maximum diameter. Binostril technique vascularized nasoseptal flap and multilayer closure of the dural defect were used. Wide sphenoidotomy, posterior ethmoidectomy, tuberculum selle, and planum removal were performed in all cases. Perioperative antibiotic prophylaxis was used for 72 h. Results: There were 44 patients of age ranging from 8 to 65 (mean: 42) years. Diameter of the tumor varied from 3.1 cm to 6.6 cm (average: 4.3 cm). Visual and pituitary dysfunctions were observed in 44 and 33, respectively, before surgery. Vision improvement, gross-total removal, cerebrospinal fluid (CSF) leak and recurrence were observed in 34, 26, four and six patients, respectively. Average follow-up was 19 months. Conclusion: Endoscopic endonasal trans-sphenoidal approach for craniopharyngioma is safe and effective alternative to transcranial approach in selected patients. Although this technique is associated with effective tumor removal and improved visual outcome, CSF leak, and endocrine dysfunctions remain a major challenge.
Management of superior sagittal sinus injury encountered in traumatic head injury patients: Analysis of 15 cases
Authors: Behera Sanjay , Senapati Satya , Mishra Sudhansu , Das Srikant
Published: February 2015

Background: Significant dural sinus injury occurs in 1.5- 5% of all head injuries and injury to superior sagittal sinus accounts for 70-80% of these. Its management is also a challenging issue to every neurosurgeon. Materials and Methods: In a period of one year (Aug 2011 to july2012) out of 549 cases of head injuries operated in our department analysis of 15 cases (2.73%) shown to have superior sagittal sinus injury. Three dimensional reconstruction of skull bone during CT scan helped us to diagnose possible dural sinus injury pre-operatively. Results: SSS injury was due to direct impact of fracture segment (5 cases), extension of fracture line over sinus area (4 cases) or due to coronal suture diastases (6 cases). Injury to anterior third of sagittal sinus occurred in 12 cases (80%) and injury to middle third occurred in 3 cases (20%). Small tear over superior sagittal sinus was found in 7 cases (46.66%) and was managed with Gelfoam; compression only and in two cases (13.33%) were large tear, which was managed with sinoraphy. In four cases (36.34%) hitch stitches over Gelfoam; to adjacent bone given and in rest two cases (13.33%) a strip of bone was left over the sinus area and bilateral hitch stitches were applied. Conclusion: Injury to SSS in traumatic head injury patient though rarely encountered during surgery, the management is challenging to every neurosurgeon. Preoperative suspicion and combination of surgical techniques rather than one single technique may be effective in decreasing the sinus related mortality rate.
Circumferential fusion for severe post surgical cervical kyphosis
Authors: Singh Sunil , Srivastava Chhitij , Ojha Bal , Chandra Anil
Published: February 2015

Cervical kyphosis-though a common occurrence after surgery and other conditions like trauma, infections, etc., is usually restricted to around 20-40°. It is more common in children. Angulations of more than 70-80° are exceedingly uncommon and present more treatment challenges. We discuss here the management of a 14-year-old child with a severe postoperative cervical kyphotic angulation of 92°. The child presented 10 months after surgery for a C3-C4 intramedullary cyst with neck deformity and near tetraplegic state. He underwent a combined anterior-posterior approach for correction after a trial of skull traction. Six months after the surgery, the child was ambulatory with almost total correction of the deformity. Surgical correction of postoperative cervical kyphosis usually involves a posterior approach for small angles and an anterior approach for larger angulations. The combined anterior-posterior approach is preferred for severe angulations or for those cases not correctable by a single approach. A purely posterior approach may be the only option for those cases where the anterior approach is impossible.
An outcome measure of functionality and pain in patients with low back disorder: A validation study of the Iranian version of Core Outcome Measures Index
Authors: Mohammadi Hasan , Azimi Parisa , Zali Alireza , Montazeri Ali
Published: February 2015

Background: Lumbar Disc Herniation (LDH) and Lumbar Spinal Stenosis (LSS) are the most common diagnoses of low back and leg pain symptoms. This study aimed to cross-culturally translate, and validate the Core Outcome Measures Index (COMI) in Iran. Methods: The translation and cross-cultural adaptation of the original questionnaire were performed in accordance with published guidelines. A total of 121 patients with LDH or LSS were asked to respond to the questionnaire at two points in time: Pre and postoperative assessments (6 months follow-up). The Oswestry Disability Index (ODI) also was completed. To test the reliability, the internal consistency was assessed by Cronbach's alpha coefficient, and validity was assessed using convergent validity. Responsiveness to change also was assessed for comparing patients' pre and postoperative scores. Results: The Cronbach's alpha coefficients for the COMI at pre and postoperative assessments ranged from 0.79 to 0.82, indicating a good internal consistency. The change in the ODI after surgery was strongly correlated with change in the COMI, lending support to its good convergent validity (r = 0.79 for LDH and r = 0.77 for LSS; P < 0.001). In addition, the correlation of each item with its hypothesized subscale of the COMI showed satisfactory results suggesting, that the items had a substantial association with the subscale, representing the concept. Further analysis also indicated that the questionnaire was responsive to change (P < 0.0001). Conclusion: The Iranian version of COMI performed well, and the findings suggest that it is a reliable and valid measure of back pain treatment evaluation among LDH and lumbar canal stenosis patients.
Cavernomas: Outcomes after gamma-knife radiosurgery in Iran
Authors: Azimi Parisa , Shahzadi Sohrab , Bitaraf Mohammad , Azar Maziar , Alikhani Mazdak , Zali Alireza , Sadeghi Sohrab
Published: February 2015

Background: Treatment of cavernomas remains a challenge in surgically inaccessible regions. The purpose of this study was to evaluate outcomes after gamma-knife surgery (GKS) for these patients. Materials and Methods: A retrospective review of 100 patients treated between 2003 and 2011 was conducted in order to evaluate hemorrhage rates, complications, radiation effects after GKS. Dosage at the tumor margin was stratified into two groups: those that received ≤13 Gy; and those who received >13 Gy. The demographic and clinical characteristics of patients including age, gender, and hemorrhage rates were extracted from care records. Results: The median age was 32.5 years (ranging from 15 to 79). 44% were female. The median follow-up time was 42.2 months (ranging from 24 to 90). The median volume of the lesions was 1050.0 mm 3 (ranging from 112.0 to 4100.0) before GKS. A reduction of 27.5% in median size of cavernomas was achieved at the last follow-up. There was 12% treatment-related morbidity after GKS. The hemorrhage rate in the first 2 years after GKS was 4.1% and 1.9% thereafter. There was no mortality due to GKS, and 93 patients were alive at the last follow-up. The radiation-related complication developed with marginal dose 13 Gy. Conclusion: The GKS for cavernomas appears to be a safe and beneficial in carefully selected patients. Low-dose GKS may be effective for the management of cavernous malformations.
Posterior lumbar interbody fusion and posterolateral fusion: Analogous procedures in decreasing the index of disability in patients with spondylolisthesis
Authors: Alijani Babak , Emamhadi Mohamahreza , Behzadnia Hamid , Aramnia Ali , Chabok Shahrokh , Ramtinfar Sara , Leili Ehsan , Golmohamadi Shabnam
Published: February 2015

Objective: The purpose of this study was to evaluate the disability in patients with spondylolisthesis who assigned either to posterolateral fusion (PLF) or posterior lumbar interbody fusion (PLIF) and to compare it between two groups. Methods: In a prospective observational study, 102 surgical candidates with low-grade degenerative and isthmic spondylolisthesis enrolled from 2012 to 2014, and randomly assigned into two groups: PLF and PLIF. Evaluation of disability has been done by a questionnaire using Oswestry Disability Index (ODI). The questionnaire was completed by all patients before the surgery, the day after surgery, after 6 months and after 1-year. Results: There were no statistically significant differences in terms of age and sex distribution and pre-operation ODI between groups (P > 0.05). Comparison of the mean ODI scores of two groups over the whole study period showed no significant statistical difference (P = 0.074). ODIs also showed no significant differences between two groups the day after surgery, 6 th months and 1-year after surgery (P = 0.385, P = 0.093, P = 0.122 and P = 433) respectively. Analyzing the course of ODI over the study period, showed a significant descending pattern for either of groups (P < 0.0001). Conclusion: Both surgical fusion techniques (PLF and PLIF) were efficient to lessen the disability of patients with spondylolisthesis, and none of the fusion techniques were related to a better outcome in terms of disability.
Isolated unilateral oculomotor nerve neuropraxia following a trivial fall in a patient with calcified posterior petroclinoid ligament
Authors: Patwardhan Maneesha
Published: February 2015

Isolated traumatic oculomotor nerve palsy caused by a trivial fall is extremely rare. We report a case of this condition. A 49-year-old woman had distal radius fracture and ptosis on the same side after having a trivial domestic fall. She did not show any clinical or radiological signs of head injury. Computerized tomography revealed a calcified posterior petroclinoid ligament which has direct anatomical and pathological relation with the oculomotor nerve.
Atypical craniocerebral eumycetoma: A case report and review of literature
Authors: Rao Kommu , Praveen Ankathi , Megha Santhavir , Sundaram Challa , Purohith Anirudh
Published: February 2015

Craniocerebral eumycetomas are rare. They usually present with scalp swelling and discharging sinuses. Radiologically, they present as space-occupying lesions. We report a case of eumycetoma involving the left parietal cortex, bone, and subcutaneous tissue in a young male, farm laborer, who presented with seizures and blurring of vision. Imaging showed a dural based lesions enhancing moderately on contrast. To the best of our knowledge and belief, ours is the first published case in the English Literature where a eumycetoma has presented as a mass lesion without discharging sinuses. It is imperative to keep such atypical features of an infective etiology in mind because they may be one of differentials of "dural" based lesions where only a biopsy may suffice in the absence of significant mass effect to prove the diagnosis.
Metachronous spinal metastases from supratentorial anaplastic astrocytoma
Authors: Raheja Amol , Borkar Sachin , Kumar Rajinder , Suri Vaishali , Sharma Bhawani
Published: February 2015

Leptomeningeal spinal metastases from supratentorial high-grade glioma are relatively rare. Authors report an unusual case of metachronous, symptomatic, dual spinal drop metastases in a 20-year-old male patient who was operated for right insular anaplastic astrocytoma 20 months earlier. Surgical decompression of the symptomatic D11-L2 drop metastasis was carried out. Histo-pathological examination revealed features suggestive of glioblastoma multiforme. Patient was advised postoperative radiotherapy. The pertinent literature is reviewed regarding this uncommon entity.
Orbital intraconal abducens nerve schwannoma: A case report and review of the literature
Authors: Bhaganagare Amresh , Bidkar Vishakha , Rodrigus Elvis , Naik Vikas , Pai Balaji
Published: February 2015

Authors report a case of right orbital intraconal abducens nerve schwannoma in a 32-year lady, who presented with a sense of tightness and discomfort in right eye on looking extreme right side since 4 months. The tumor was totally excised with functional preservation of the nerve by superior orbitotomy. The clinical, radiological features and the management are discussed.
Mapping Splicing Quantitative Trait Loci in RNA-Seq
Authors: Jia Cheng , Hu Yu , Liu Yichuan , Li Mingyao
Published: February 2015

Background

One of the major mechanisms of generating mRNA diversity is alternative splicing, a regulated process that allows for the flexibility of producing functionally different proteins from the same genomic sequences. This process is often altered in cancer cells to produce aberrant proteins that drive the progression of cancer. A better understanding of the misregulation of alternative splicing will shed light on the development of novel targets for pharmacological interventions of cancer.

Methods

In this study, we evaluated three statistical methods, random effects meta-regression, beta regression, and generalized linear mixed effects model, for the analysis of splicing quantitative trait loci (sQTL) using RNA-Seq data. All the three methods use exon-inclusion levels estimated by the PennSeq algorithm, a statistical method that utilizes paired-end reads and accounts for non-uniform sequencing coverage.

Results

Using both simulated and real RNA-Seq datasets, we compared these three methods with GLiMMPS, a recently developed method for sQTL analysis. Our results indicate that the most reliable and powerful method was the random effects meta-regression approach, which identified sQTLs at low false discovery rates but higher power when compared to GLiMMPS.

Conclusions

We have evaluated three statistical methods for the analysis of sQTLs in RNA-Seq. Results from our study will be instructive for researchers in selecting the appropriate statistical methods for sQTL analysis.
Radio y redes sociales: el caso de los programas deportivos en Twitter
Authors: Pérez Dasilva Jesús Ángel , Santos María Teresa , Meso Ayerdi Koldobika
Published: February 2015

Esta investigación analiza las cuentas en la red de microblogging de los programas deportivos estrella de la radio. Este tipo de periodismo se sirve de esta herramienta para aumentar su visibilidad y destaca por la influencia y repercusión que obtienen sus mensajes en la red. Metodología. Se han analizado los 3.200 mensajes más recientes en cada una de las cuentas de los programas deportivos radiofónicos más escuchados mediante una ficha de análisis que contiene 20 indicadores agrupados en potencial de influencia, actividad, interacción y reacciones generadas en los usuarios. Conclusiones. Queda demostrada la repercusión que tienen sus mensajes en la red social. La tasa de amplificación se sitúa entre el 50 y el 80% y la tasa de gratificación entre el 40 y el 85%. Esto indica que son espacios muy influyentes con gran capacidad de prescripción debido al interés que despierta el deporte y todo lo que le rodea.
Influence of satellite-derived photolysis rates and NOx emissions on Texas ozone modeling
Authors: Tang W. , Cohan D. S. , Pour-Biazar A. , Lamsal L. N. , White A. T. , Xiao X. , Zhou W. , Henderson B. H. , Lash B. F.
Published: February 2015

Abstract. Uncertain photolysis rates and emission inventory impair the accuracy of state-level ozone (O3) regulatory modeling. Past studies have separately used satellite-observed clouds to correct the model-predicted photolysis rates, or satellite-constrained top-down NOx emissions to identify and reduce uncertainties in bottom-up NOx emissions. However, the joint application of multiple satellite-derived model inputs to improve O3 state implementation plan (SIP) modeling has rarely been explored. In this study, Geostationary Operational Environmental Satellite (GOES) observations of clouds are applied to derive the photolysis rates, replacing those used in Texas SIP modeling. This changes modeled O3 concentrations by up to 80 ppb and improves O3 simulations by reducing modeled normalized mean bias (NMB) and normalized mean error (NME) by up to 0.1. A sector-based discrete Kalman filter (DKF) inversion approach is incorporated with the Comprehensive Air Quality Model with extensions (CAMx)–decoupled direct method (DDM) model to adjust Texas NOx emissions using a high-resolution Ozone Monitoring Instrument (OMI) NO2 product. The discrepancy between OMI and CAMx NO2 vertical column densities (VCDs) is further reduced by increasing modeled NOx lifetime and adding an artificial amount of NO2 in the upper troposphere. The region-based DKF inversion suggests increasing NOx emissions by 10–50% in most regions, deteriorating the model performance in predicting ground NO2 and O3, while the sector-based DKF inversion tends to scale down area and nonroad NOx emissions by 50%, leading to a 2–5 ppb decrease in ground 8 h O3 predictions. Model performance in simulating ground NO2 and O3 are improved using sector-based inversion-constrained NOx emissions, with 0.25 and 0.04 reductions in NMBs and 0.13 and 0.04 reductions in NMEs, respectively. Using both GOES-derived photolysis rates and OMI-constrained NOx emissions together reduces modeled NMB and NME by 0.05, increases the model correlation with ground measurement in O3 simulations, and makes O3 more sensitive to NOx emissions in the O3 non-attainment areas.
Steady-state solutions for subsurface chlorophyll maximum in stratified water columns with a bell-shaped vertical profile of chlorophyll
Authors: Gong X. , Shi J. , Gao H. W. , Yao X. H.
Published: February 2015

Abstract. A bell-shaped vertical profile of chlorophyll a (Chl a) concentration, conventionally referred to as a subsurface chlorophyll maximum (SCM) phenomenon, has frequently been observed in stratified oceans and lakes. This profile is assumed to be a general Gaussian distribution in this study. By substituting the general Gaussian function into ecosystem dynamical equations, the steady-state solutions for SCM characteristics (i.e., SCM layer depth, thickness, and intensity) in various scenarios are derived. These solutions indicate that (1) the maximum concentration of Chl a occurs at or below the depth of maximum growth rates of phytoplankton located at the transition from nutrient limitation to light limitation, and the depth of SCM layer deepens logarithmically with an increase in surface light intensity; (2) thickness and intensity of the SCM layer are mainly affected by nutrient supply, but independent of surface light intensity; and (3) intensity of the SCM layer is proportional to the diffusive flux of nutrients from below, which becomes stronger as a result of this layer being shrunk by a higher light attenuation coefficient or a larger sinking velocity of phytoplankton. In addition, the limitation and potential application of the analytical solutions are also presented.
Long-term spatial and temporal variation of CO2 partial pressure in the Yellow River, China
Authors: Ran L. , Lu X. X. , Richey J. E. , Sun H. , Han J. , Yu R. , Liao S. , Yi Q.
Published: February 2015

Abstract. Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). By determining the pCO2 from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950s–1984) and recent sampling along the mainstem (2011–2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e. 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to > 30 000 μatm with higher pCO2 usually occurring in the dry season and lower pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg m−3, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg m−3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, large potential for CO2 evasion is expected and warrants further investigation.