Angle Region Research Articles

Numerical simulation of angled-injected liquid jet breakup in supersonic crossflow by a hybrid VOF-LPT method

The breakup of angled-injected liquid jets in supersonic airflow is investigated numerically by a hybrid Volume of Fluid and Lagrangian Particle Tracking (VOF-LPT) method. A Multi-criterion adaptive mesh refinement (AMR) procedure and dynamic load balancing (DLB) algorithm are applied to improve the accuracy of interface and shock wave characteristics and reduce the use of computational resources and liquid mass loss. The flow characteristics of the spray field and penetration depth of the angled-injected liquid jet from the simulations agreed well with the experimental results. Under the supersonic crossflow conditions, the jet has momentum in the counter-flow direction that improves gas-liquid interactions. The penetration depth of the liquid jet increase with the increase of the injection angle. In particular, the penetration depth of the angled-injected liquid jet is given in the: y/d=0.12·sin(2θ/3)·(esin(2θ/3))3.185·q0.389(x/d)0.309. Moreover, the liquid jet at a larger injection angle has a larger spray spread angle and wider wake region due to the larger windward area. Furthermore, the total pressure loss of airflow increases with the injection angle increasing. Considering the total pressure loss for all injection conditions is lower than 14%, the total pressure loss caused by the injection angle increase can be negligible.

Robust Space-Time Adaptive Processing Method for GNSS Receivers in Coherent Signal Environments

In the coherent signal environments caused by multipath propagation, the interference suppression performance of the global navigation satellite systems (GNSS) receivers decreases sharply. In this paper, a robust space-time adaptive processing (STAP) method for GNSS receivers is proposed to suppress interferences in coherent signal environments, by using the modified space-time two-dimensional iterative adaptive approach (ST2D-IAA) spectrum estimation. This method applies the IAA algorithm to the ST2D signal model of GNSS receivers, and further modifies the ST2D-IAA algorithm to accurately estimate the power spectrum and noise power simultaneously. The space-time interference-plus-noise covariance matrix (STINCM) is reconstructed by using the estimated power spectrum and noise power in the interference angle region. Based on the reconstructed STINCM, we construct the STAP beamforming optimization problem for the space-time steering vector (STSV) error vector, and further correct the STSV of GNSS signal. Finally, the weight vector of STAP beamforming is calculated by using the reconstructed STINCM and the corrected STSV of GNSS signal. Simulation results show that the proposed method can suppress interferences in coherent signal environments and outperforms the current methods.

SDPS-06 A 4 YEAR-OLD GIRL WITH EMBRYONAL RHABDOMYOSARCOMA IN RETROAURICULAR AND MIDDLE EAR : A RARE CASE REPORT FROM INDONESIA

Abstract Rhabdomyosarcoma is the most common sarcoma of childhood, and this tumor is the third most common neoplasm after neuroblastoma and nephroblastoma. Rhabdomyosarcomas may originate in any anatomical site, occurring predominantly in head and neck regions, orbits, skull base, nasal cavity, and nasopharynx, where there is little or no musculoskeletal tissue. The involvement of the ear and mastoid bone in rhabdomyosarcoma is uncommon. The embryonal rhabdomyosarcoma includes about 60– 70% of rhabdomyosarcoma cases. A four years-old girl presented with pain in neck and difficult to moving, there was a mass in the left auricular that was getting bigger. 4 days prior to admission, there was a drooping mouth to the left, the voice sounds hoarse, but there was no weakness in the side and no loss of consciousness. On physical examination, there was a N.VII palsy, without hyperreflexia, paraplegia, and nystagmus. High resolution Mastoid CT-Scan showed a characteristic malignant solid mass involving the external acoustic canal and the left tympanic and mastoid cavities, destroying the auditory and temporal bones, involving the left internal acoustic canal, and reaching the left nasopharynx, extending into the intracranial region of the left cerebellopontine angle and left temporal duramater. In Pathology examination showed Tumor cells are spherical, spindle-shaped with pleomorphic nuclei, hyperchromatic, coarse chromatin, vesicular, some with real nuclear daughters, eosinophilic cytoplasm. Mitosis is discovered. eccentricallynucleated cells with eosinophilic cytoplasm, suggesting rhabdomyoblast differentiation, some with a "tadpole" appearance, and conclusion according to embryonal rhabdomyosarcoma. The patient is treated with chemotherapy using Vincristine, Actinomycin-D, and Ifosfamide.

Shape recovery from fusion of polarization binocular vision and shading.

The shape from polarization can recover the fine texture of the target surface. However, the gradient field for shape recovery by polarization is ambiguous, which is caused by the multi-value of the azimuth angle. In response to the problem, a method of correcting the ambiguity by the fusion of polarization binocular vision and shading information is proposed in this paper. An iterative optimization algorithm is designed to estimate the direction of the light source, which provides the basis for the shading method to calculate the depth map. Additionally. the low-frequency depth map generated by binocular matching is used to correct the polarization gradient field. The polarization gradient field of the holes and small zenith angle regions in the binocular are corrected by the improved shading method. In the experiment, four different material target objects were used for shape recovery and compared with other methods. The results of the fusion method proposed are better in terms of fine texture. At the camera working distance of 700mm, the resolving power performs well and demonstrates that changes in the depth of at least 0.1mm can be distinguished from that recovery result.

Non-self-adjoint model statement of boundary problem of acoustics. Part 1

Based on the mathematical definition of a non-self-adjoint operator and the physical meaning of a specific boundary value problem, a non-self-adjoint model statement of boundary value problems in acoustics is formulated. As an example, boundary value problems for the reflection of a plane wave and a spherical wave at the interface between two liquid media are considered. A new definition of the reflection coefficient of a spherical wave is introduced. In the region of subcritical angles of incidence, the new definition takes into account the appearance in the total sound field of converging recoil waves corresponding to the eigenfunctions of the adjoint operator. In the region of supercritical angles of incidence, the participation of the eigenfunctions of two conjugate operators in the total sound field forms a nonzero power flux through the interface and its transformation into the vortex component of the intensity vector at the total internal reflection horizon. The definition of the total internal reflection horizon is given. Experimental data are presented that confirm the new definition of the reflection coefficient and the physical correctness of the non-self-adjoint model statement.

Three-dimensional yaw wake model development with validations from wind tunnel experiments

The presence of wake flows caused by wind turbines (WTs) diminish the expected power generation of wind energy and exacerbate structural vibrations. To mitigate these issues, yaw control has emerged as a promising technique for intentionally deflecting the wake away from downstream WTs. Consequently, accurate prediction of the yawed wake is of paramount importance for effective implementation of yaw control strategies. This study presents an innovative and comprehensive approach to modeling yaw wake behavior by introducing an advanced three-dimensional yaw wake model. This model incorporates anisotropic and general expressions of the wake expansion rate, allowing for a more accurate and physically meaningful representation of wake evolution. More importantly, the easily-available parameters in the function guarantee the generalization capability of the proposed model. Subsequently, a wake deflection mode is developed and integrated into the yaw wake model through the inclusion of a deflection term. To validate the proposed models, two sources of data are utilized. Firstly, well-known public measurements are used to verify the accuracy and reliability of the model predictions. Secondly, wind tunnel experiments are conducted by the authors, employing a particle image velocimetry (PIV) system to capture detailed flow field information. This combination of validation sources ensures a comprehensive assessment of the proposed models. The physical description and error analysis conducted in this study reveals that the proposed model outperforms other models in terms of predicting wake distribution and the trajectory of the deflected wake centreline. In particular, the comparative analysis confirms its superior performance in the main angle and downstream region that are of particular interest for active yaw control. The accurate and cost-efficient nature of the proposed analytical yaw wake model holds great potential for optimizing yaw control strategies in wind farms. This study is expected to contribute to the field by offering a reliable and practical tool for understanding and managing the effects of yaw operation on wake behavior.

Enhancing the Power-Extraction Efficiency of a Flapping Foil by Active Morphing

A computational study of two morphing, power-extracting flapping foils (a NACA 0015 at and a flat plate at ) is conducted by considering three strategies: morphing of the leading edge (LE) or trailing edge (TE) alone, and morphing of both LE and TE simultaneously. The morphing variables are the phase shift and frequency of the edge deformation. All cases take into account the power required to morph the foils. The independently morphing LE/TE edge cases show regions of phase angle and frequency that yield improved efficiency over the rigid baseline of up to 16.8% for the NACA 0015 foil and 22.6% in the flat-plate case. The combined LE and TE cases further increase the efficiency, up to 29.7% for the NACA 0015 foil and 36.2% in the flat-plate case. Three physical mechanisms are identified that lead to efficiency increases in the various cases through the interaction between the morphing foil and shed vortex structure. These are the change in projected area during the plunging stroke, the variation of leading-edge vortex shedding timing during the cycle, and the proximity of the shed vortex structure to the foil during the pitching portion of the stroke.

Cavitation characteristics and energy loss in high-pressure differential control valve

PurposeThe purpose of this study is to determine the cavitation flow characteristics of the high-pressure differential control valve. The relationship between cavitation, flow coefficient and spool angle is obtained. By analyzing the relationship between different spool angles and energy loss, the energy loss at different spool angles is predicted.Design/methodology/approachA series of numerical simulations were performed to study the cavitation problem of a high-pressure differential control valve using the RNG k–e turbulence model and the Zwart cavitation model. The flow states and energy distribution at different spool angles were analyzed under specific working conditions.FindingsThe cavitation was the weakest when the spool angle was 120° or the outlet pressure was 8 MPa. The pressure and speed fluctuations of the valve in the throttle section were greater than those at other locations. By calculating the entropy production rate, the reason and location of valve energy loss are analyzed. The energy loss near the throttling section accounts for about 92.7% of the total energy loss. According to the calculated energy loss relationship between different regions of the spool angle, the relationship between any spool angle and energy loss in the [80,120] interval is proposed.Originality/valueThis study analyzes the cavitation flow characteristics of the high-pressure differential control valve and provides the law of energy loss in the valve through the analysis method of entropy. The relationship between spool angle and energy loss under cavitation is finally proposed. The research results are expected to provide a theoretical basis for the optimal design of valves.

Primary intracranial sarcomas: a clinicopathological investigation.

The purpose of this study is to present a series of primary intracranial sarcomas (PIS), a rare type of tumor of the central nervous system, in order to improve our understanding of the disease. These tumors are heterogeneous and prone to recurrence after resection, exhibiting a high mortality rate. As PIS has yet to be understood and studied on a large scale, it is vital for further evaluation and research. Our study included 14 cases of PIS. The patients' clinical, pathological, and imaging features were retrospectively analyzed. Additionally, targeted DNA next-generation sequencing (NGS) was applied for the 481-gene panel to detect gene mutations. The average age for PIS patients was 31.4 years. Headache (7, 50.0%) was the most common symptom leading to the hospital visit. Twelve cases had PIS located in the supratentorial area and two in the cerebellopontine angle region. The maximum tumor diameter ranged from 19.0mm to 130.0mm, with an average diameter of 50.3mm. Pathological types of tumors were heterogeneous, with chondrosarcoma being the most common, followed by fibrosarcoma. Eight of the 10 PIS cases that underwent MRI scanning showed gadolinium enhancement; 7 of these cases were heterogeneous, and 1 of them was garland-like. Targeted sequencing was performed in two cases and identified mutations in genes such as NRAS, PIK3CA, BAP1, KDR, BLM, PBRM1, TOP2A, DUSP2, and CNV deletions of SMARCB1. Additionally, the SH3BP5::RAF1 fusion gene was also detected. Of the 14 patients, 9 underwent a gross total resection (GTR), and 5 chose subtotal resection. Patients who underwent GTR displayed a trend toward superior survival. Among the 11 patients with available follow-up information, one had developed lung metastases, three had died, and eight were alive. PIS is extremely rare compared to extracranial soft sarcomas. The most common histological type of intracranial sarcoma (IS) is chondrosarcoma. Patients who underwent GTR of these lesions showed improved survival rates. Recent advancements in NGS aided in the identification of diagnostic and therapeutic PIS-relevant targets.

Tridimensional assessment of the mandibular angle in patients with different skeletal patterns by cone-beam computed tomography scans: a retrospective study

BackgroundSince the muscles of chewing are involved in the region of the mandibular angle, important structures in surgical and orthodontic procedures, to study its morphological aspects and the possible influence of different patterns of skeletal development would be of interest. Thus, this study aimed to assess the influence of patient characteristics - such as sex, skeletal malocclusion (Class I, Class II, and Class III) and facial type (brachycephalic, mesocephalic, and dolichocephalic) - on the width, height, thickness, and volume of the mandibular angle, using cone-beam computed tomography (CBCT) scans.MethodsCBCT scans were assessed − 144 men and 154 women, total of 298 - and classified according to skeletal patterns (skeletal malocclusions and facial types). Width, height, and thickness of the mandibular angle were measured using OnDemand 3D software. The volumetric measures of the mandibular angle were obtained using the ITK-SNAP software. Analysis of Variance (multiway ANOVA) with Tukey’s post-hoc test compared the data, with a 5% significance level.ResultsAmong the factors studied, sex significantly influenced all the analyzed variables (height, width, thickness, and volume of the mandibular angle) (p < 0.05); in general, male individuals presented higher values than females. In some cases, the skeletal malocclusion and facial type factors influenced only the width and height variables (p < 0.05); in general, the Class III and dolichocephalic individuals presented higher values in relation to the other types of skeletal malocclusions and facial types.ConclusionsVariations in the craniofacial growth pattern, considering the different skeletal malocclusions and facial types, had some influence in the width and height dimensions of the mandibular angle. Furthermore, sex influenced all the studied variables.

Machine diagnosis of chronic obstructive pulmonary disease using a novel fast-response capnometer

BackgroundAlthough currently most widely used in mechanical ventilation and cardiopulmonary resuscitation, features of the carbon dioxide (CO2) waveform produced through capnometry have been shown to correlate with V/Q mismatch, dead space volume, type of breathing pattern, and small airway obstruction. This study applied feature engineering and machine learning techniques to capnography data collected by the N-Tidal™ device across four clinical studies to build a classifier that could distinguish CO2 recordings (capnograms) of patients with COPD from those without COPD.MethodsCapnography data from four longitudinal observational studies (CBRS, GBRS, CBRS2 and ABRS) was analysed from 295 patients, generating a total of 88,186 capnograms. CO2 sensor data was processed using TidalSense’s regulated cloud platform, performing real-time geometric analysis on CO2 waveforms to generate 82 physiologic features per capnogram. These features were used to train machine learning classifiers to discriminate COPD from ‘non-COPD’ (a group that included healthy participants and those with other cardiorespiratory conditions); model performance was validated on independent test sets.ResultsThe best machine learning model (XGBoost) performance provided a class-balanced AUROC of 0.985 ± 0.013, positive predictive value (PPV) of 0.914 ± 0.039 and sensitivity of 0.915 ± 0.066 for a diagnosis of COPD. The waveform features that are most important for driving classification are related to the alpha angle and expiratory plateau regions. These features correlated with spirometry readings, supporting their proposed properties as markers of COPD.ConclusionThe N-Tidal™ device can be used to accurately diagnose COPD in near-real-time, lending support to future use in a clinical setting.Trial registration: Please see NCT03615365, NCT02814253, NCT04504838 and NCT03356288.

51‐4: Collimated Organic Molecular Beam Made by Triple Nozzle Evaporator

We developed triple nozzle evaporator that can make collimated organic molecular beam. We can reduce inner pressure below final nozzle 1/150 times lower than general evaporator by using triple nozzle structure and recycling path. As a results, the angular flux distribution of triple nozzle evaporator is similar with the cosine to the 100 th graph. And 80% of total flux are concentrated within only ±8° angle region. We expect that it will be helpful to achieve ultra‐high resolution in AMOLED AR/VR and increase material utilization in AMOLED mass production.

Management of Temporomandibular Joint Reankylosis: A Case Series.

Background Temporomandibular joint ankylosis is a severe debilitating clinical condition where there is fusion of the mandible with the temporal bone. It is often a challenge to the maxillofacial surgeon as the surgical treatment protocol must be tailored individually according to the time of presentation of the ankylosis, and proper postoperative aggressive physiotherapy must be advocated, which is essential for a successful outcome. This is a case series of six recurrent temporomandibular joint ankylosis, in which the historical Esmarch surgery was done, and the pterygomassetric sling was interposed between the osteotomized segments. Postoperative mouth opening and surgical outcome were satisfactory. In our cases, we created a pseudojoint, which was very successful using the Esmarch procedure. Aim We aim to improve mouth opening in patients presenting with temporomandibular joint reankylosis using the Esmarch procedure and evaluate the efficacy of the conventional and modified Esmarch procedure. Materials and methods We have included six cases of recurrent temporomandibular joint reankylosis. Five cases were operated on using the conventional Esmarch procedure in which the osteotomy was done at the angle region, below the inferior alveolar nerve canal, and one case using the modified Esmarch procedure, wherein the osteotomy was done above the inferior alveolar nerve canal. The patients included in the case series presented withtemporomandibular joint reankylosis and had undergone multiple surgeries for the release of ankylosis. Results Satisfactory postoperative mouth opening was achieved in all six patients. It wasobserved that in the modified Esmarch osteotomy, where the cuts were placed above the inferior alveolar nerve canal, there was a massive hemorrhage intraoperatively. This was primarily attributed to the altered anatomy of the maxillary artery, which was very close to the ankylotic mass. When the osteotomy was done below the inferior alveolar nerve canal, it was found that by this technique, the intraoperative hemorrhage was minimal, but it carries a risk of postoperative inferior alveolar nerve paresthesia, which was managed conservatively. Conclusion With the abovementioned results, we proceeded with the conventional Esmarch procedure for five cases and the modified Esmarch procedure for one case. It was found that in temporomandibular joint reankylosis cases, where there is extensive ankylotic mass extending from the glenoid fossa to the coronoid process of the mandible, this Esmarch procedure provides promising results when the osteotomy cuts are placed below the nerve canal.

Resolution of blood eosinophilia and limited mouth opening after short-term follow-up in a pediatric Langerhans cell histiocytosis case.

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia that often affects children, presenting a broad clinical spectrum. Here, we report a 13-year-old male Salvadorian patient who was referred presenting a nodular swelling at the mandibular angle region, mildly symptomatic, few weeks ago, which relevantly was associated with limited mouth opening. Intraoral examination was unremarkable. Imaginological exams revealed an osteolytic lesion affecting the vestibular cortex at the right mandibular angle. The blood test results were normal, except for eosinophilia (21%; absolute eosinophil count 4 × 109/L). After an incisional biopsy, microscopical and immunohistochemical analyses were consistent with LCH diagnosis, which corresponded to a single system-single site category. After a few weeks, the mandibular movements were re-established, and complete resolution of blood eosinophilia was observed. LCH with blood eosinophilia is rarely reported. To our knowledge, 3 cases have been previously published.

Rare Cortical and Intraparenchymal Epidermoid Cyst within the Right Occipital Lobe (P3-4.004)

<h3>Objective:</h3> N/A <h3>Background:</h3> The differential diagnosis for a diffusion-restricting cortical lesion on brain magnetic resonance imaging (MRI) is broad and includes acute ischemic stroke, abscess, demyelination, Creutzfeldt Jakob disease, encephalitis, and epidermoid cyst. <h3>Design/Methods:</h3> <h3>Case description:</h3> A 13-year-old boy with accelerated growth underwent MRI for pituitary assessment, which incidentally demonstrated a non-enhancing, T2 hyperintense right occipital lesion. No diffusion weighted imaging (DWI) sequences were obtained, and the lesion was suspected to represent encephalomalacia. Five years later, he developed left visual field difficulties and repeat MRI identified right occipital lesional growth with high DWI and low apparent diffusion coefficient (ADC) signal. The patient underwent resection of the right occipital lesion. Histopathology revealed keratin encapsulated by squamous epithelium, consistent with an epidermoid cyst. Our patient is currently doing well, and his left visual field vision is improved. <h3>Results:</h3> <h3>Discussion:</h3> Intracranial epidermoid cysts comprise 1% of primary intracranial tumors and are derived from ectodermal inclusions during neural tube closure. They usually present in middle age due to mass effect on adjacent structures. Epidermoid cysts most commonly occur at the cerebellopontine angle and parasellar region. A cortical location of an intracranial epidermoid cyst, as in our patient’s case, is very rare. The signal intensity of the epidermoid cyst on MRI is variable due to its composition of keratin and lipids and there is usually no associated edema. Total surgical excision is the mainstay of treatment for intracranial epidermoid cysts. Recurrence is not uncommon, but growth is usually slow over many years. <h3>Conclusions:</h3> Neurologists should include intraparenchymal epidermoid cysts in the differential diagnosis for a diffusion restricting lesion on MRI of the brain. <b>Disclosure:</b> Dr. Webb has nothing to disclose. The institution of Dr. Burns has received research support from NIH (NINDS, NCI), DOD, ABTA, Ivy foundation, insightec, Mayo Clinic, Abbvie, . Dr. Zhang has nothing to disclose. Dr. Sener has nothing to disclose.

The marvelous dna macromolecule: computer modeling of dna 3d structure and diversity of watson-crick duplex conformations

The work reviews the development of ideas about the 3D structure of DNA and the mechanisms of its formation, from the discovery of the Double Helix to the present day. It tracks the methods of modeling the 3D structure at different stages of the study of the main molecule of life. The discussion underscores a marvelous expedient in DNA molecular structure and its adaptability to important biological functions based on the results of calculations of the intra- and intermolecular interactions of macromolecule subunits. The work presents new data about substantial contribution of chemically monotonous and conformationally flexible sugarphosphate backbone to the formation of sequence-dependent 3D structure of DNA. The diversity of the conformational possibilities of DNA is visible both in the formation of duplexes (as well as triplexes and quadruplexes) with different geometric parameters for base pairs and in the formation of duplexes with Watson-Crick nucleoside pairs containing local conformations corresponding to different regions of the torsion angles of the sugar-phosphate backbone (different conformational classes). Based on our calculations, these classes can be divided into two groups. The first group includes local conformations in which the torsion angles are close to one of energy minima of its isolated elemental repeating fragment, and the second group consists of conformations with one or more of these angles deviating from that of the nearest energy minimum by more than 30°. The regularities of the formation of the local 3D structure of these two groups differ significantly.

Seismic performance of steel semi-rigid friction-damped joints with replaceable angles in modern Chinese traditional-style buildings

As an important part of world-class architectural art, Chinese ancient timber architecture has a very high level of artistry and technology. However, these buildings have been seriously damaged in the long history. To inherit and reflect the national characteristics and regional culture, the modern Chinese traditional-style building (MCTB) is newly developed to imitate the appearance of Chinese ancient timber architecture. The base metal of the typical joint area in MCTBs is always fractured under earthquakes because of its rigid characteristics, which is difficult to repair once damaged. To prevent joint failure and improve reparability after earthquakes, steel semi-rigid friction-damped joints with replaceable angles in MCTBs are proposed. Four specimens were fabricated and tested under lateral cyclic loading. The test results showed that the failure of all specimens is mainly concentrated in the weak region of the replaceable angles. Compared with simple semi-rigid joints, the yield displacements of specimens with friction dampers (including shear damper and rotational damper) are obviously larger, and the strength, initial stiffness, cumulative energy dissipation and replaceable capacity are significantly improved. The improvement is more pronounced with the increase of the slip force of the dampers. Based on experimental results, the corresponding numerical models were established to optimize the structural design of steel semi-rigid friction-damped joints with replaceable angles in modern Chinese traditional-style buildings.

Circumferential groove on flow field and pressure fluctuation intensity of a semi-open centrifugal pump under design condition

The tip leakage flow (TLF) generated by the tip clearance has adverse effect on the performance of the impeller and increases pressure fluctuation. To suppress the effect of TLF on the instable flow in a semi-open centrifugal pump, the circumferential groove method is proposed in this paper. The effect of the circumferential groove on the internal flow and pressure fluctuation under the design condition is studied by combining numerical simulation with experiment. The results show that the head and efficiency were reduced by 1.1% and 1.0%, respectively. However, the circumferential groove provided a circumferential channel for leading edge overflow. The fluid in the groove formed a jet near the low-pressure region, which can effectively disperse the low-energy fluid of the blade inlet. The initial position and trajectory of the tip leakage vortex (TLV) move downstream, which decreases the relative flow angle and low-velocity region. The flow field in the blade tip region was improved remarkably. The low-frequency pressure fluctuation in the pressure surface and tip clearance of the blade inlet was suppressed by the circumferential groove, and pressure pulsation intensity decreased by 50% and 66%, respectively.

Phosphotungstic acid immobilized over SnO2 mesoporous material as a heterogeneous catalyst for fructose to 5-hydroxymethylfurfural conversion

5-Hydroxymethylfurfural (HMF) is regarded as an essential platform chemical due to its flexible nature that could be converted into a variety of value-added compounds including production of liquid fuels and fine chemicals. We have developed a phosphotungstic acid (PTA) immobilized over SnO2 mesoporous material by hydrothermally employing Pluronic P123 as a structure directing agent (SDA) to obtain a heterogeneous catalyst for fructose to HMF conversion, and the catalyst is designated as MSnPTA. The powder X-ray diffraction patterns in low angle region, type IV isotherm and fringes of the catalyst confirmed the mesoporosity of the material. The catalyst is comprised of BET surface area of 85.86 m2/g and average pore diameter of 7.9 nm. Spherical shape through worm like structure formed small particles facilitated the large surface area of the MSnPTA catalyst that prefer to occur the catalytic reaction. The uniform elemental distribution of PTA over SnO2 ascribed more active sites, resulting in high acidity of the catalyst as measured by TPD of ammonia, which increased the conversion of fructose to high yield of HMF in a short reaction time. The yield of the HMF increased as increasing the amount of catalyst and temperature as expected.

Posterolateral Routes to the Skull Base, Craniocervical Junction, and Jugular Foramen-The Far Lateral Transcondylar Approach and Combined Transpetrosal Transcervical Approaches.

The far lateral approach provides wide surgical access to the lower third of the clivus, pontomedullary junction, and anterolateral foramen magnum and rarely requires craniovertebral fusion. The most common indications for this approach are posterior inferior cerebellar artery and vertebral arteryaneurysms, brainstem cavernous malformations, and tumors anterior to the lower pons and medulla, including meningiomas of the anterior foramen magnum, schwannomas of the lower cranial nerves, and intramedullary tumors at the craniocervical junction. We provide a stepwise description of how we perform the far lateral approach, as well as how to combine the far lateral approach with other skull base approaches, including the subtemporal transtentorial approach, for lesions involving the upper clivus; the posterior transpetrosal approach, for lesions involving the cerebellopontine angle and/or petroclival region; and/or lateral cervical approaches, for lesions involving the jugular foramen or carotid sheath regions.