Search results for "Dumbbell"
showing 8 items of 18 documents
Dynamical environments of MU69: a state of chaotic clearing
2018
AbstractThe second (after Pluto) plausible target object for the New Horizons mission is 2014 MU69. It is a classical TNO, a primordial contact binary. Identifying any material in the vicinities of a target object is of an especial concern for planning cosmic fly-byes, as it is hazardous for a space probe. Luckily, no such material has been reported for MU69 up to now. The point of our report is that this lucky absence is just a dynamical consequence of the physical nature of MU69. Spinning gravitating dumbbells create zones of dynamical chaos around them, and this has a clearing effect: any material put in orbits around a rotating dumbbell (e.g., any material ejected from its surface) cann…
Combined thoracotomy and laminectomy for spinal cavernomas with intrathoracic growth.
2007
Dumbbell shaped epidural cavernomas are uncommon lesions. Of these, the extraforaminal extension is usually limited, and the lesions are removed surgically by an extended laminectomy. We present two cases of dumbbell shaped epidural cavernomas with a considerable intrathoracic growth. They were resected through a combined thoracotomy and laminectomy. Only in the case in which a wide approach to the posterior mediastinum was performed it was possible to completely remove the lesion. Since it is possible to anticipate this histological diagnosis by the magnetic resonance imaging characteristics, we propose that a wide transthoracic approach should be performed associated to a laminectomy if a…
Directional Shuttling of a Stimuli-Responsive Cone-Like Macrocycle on a Single-State Symmetric Dumbbell Axle
2018
Rotaxane-based molecular shuttles are often operated using low-symmetry axles and changing the states of the binding stations. A molecular shuttle capable of directional shuttling of an acid-responsive cone-like macrocycle on a single-state symmetric dumbbell axle is now presented. The axle contains three binding stations: one symmetric di(quaternary ammonium) station and two nonsymmetric phenyl triazole stations arranged in opposite orientations. Upon addition of an acid, the protonated macrocycle shuttles from the di(quaternary ammonium) station to the phenyl triazole binding station closer to its butyl groups. This directional shuttling presumably originates from charge repulsion and an …
Thoracic dumbbell spinal metastasis secondary to neuroendocrine tumor of unknown origin: Case report and literature review
2022
Background: Dumbbell tumors are typically benign schwannomas, neurofibromas, and meningiomas and only rarely there are malignant variants of these lesions or other malignant histotypes. Here, a 34-year-old male presented with a thoracic spinal dumbbell metastatic neuroendocrine carcinoma of unknown primary origin. Case Description: A 34-year-old male presented with 2 months of thoracic pain and progressive mid thoracic sensory loss. A post contrast thoracic MRI showed a dumbbell tumor localized between the T7 and T9 levels with extension laterally into the T7-T8 and T8-T9 foramina. The patient underwent a laminectomy for tumor resection following which his pain and gait improved. Histopath…
Concerted Halogen-Bonded Networks with N-Alkyl Ammonium Resorcinarene Bromides: From Dimeric Dumbbell to Capsular Architectures
2015
N-Alkyl ammonium resorcinarene bromides and 1,4-diiodooctafluorobutane via multiple intermolecular halogen bonds (XB) form different exotic supramolecular architectures through subtle changes of the upper rim substituents. Dimeric dumbbell-like assembly with encapsulated guest molecules is generated with N-benzyl substituents. The N-hexyl groups engender an XB-induced polymeric pseudocapsule and an XB-induced dimeric capsule with entrapped 1,4-dioxane guest molecules. The N-propyl and N-cyclohexyl groups generate deep cavity cavitands. The deep cavity cavitands possess cavities for self-inclusion leading to polymeric herringbone arrangement in one direction and that pack into 3D polymeric a…
Mean square radius of gyration and hydrodynamic radius of jointed star (dumbbell) and H-comb polymers
1996
Equations for the mean square radius of gyration and the hydrodynamic radius for jointed stars (dumbbells) and H-combs are derived, based on random flight statistics for each subchain. Comparision with literature data on computer simulations and experimental data for H-combs show good agreement for the g-value of the mean square radius of gyration even in good solvents. This suggests that for the mean square radius of gyration the relative dimension of a H-comb relative to the linear molecule of the same degree of polymerization is not altered significantly by long range interactions, as in the case of star polymers. For the hydrodynamic radius the situation is different. Fair agreement is …
Primary intra and extradural solitary fibrous tumor/hemangiopericytoma of thoracic spine with paravertebral intrathoracic spread: Case report and rev…
2020
Abstract Solitary fibrous tumors/hemangiopericytomas (SFTs/HPCs), constitute 1% of all CNS tumors. Spinal SFTs/HPCs are extremely rare. To date, few retrospective studies and case reports of primary spinal SFTs/HPCs have been published in the literature. We report clinical and radiological presentation, surgical treatment, and post-operative outcome at three years follow-up of a rare case of primary spinal intra and extradural SFT/HPC of thoracic spine with dumbbell shaped paravertebral intrathoracic spread and multidirectional erosion of the bone. A 73-year-old female presented with progressive lower limbs weakness and hypoesthesia below the rib cage. MRI showed an irregular isointense T5-…
Thoracic dumbbell spinal chordoma mimicking a schwannoma
2021
Background: Epidural dumbbell-shaped chordomas are localized slow growing, and malignant/aggressive neoplasms. Here, we present a 62-year-old male with a T3-T4 dumbbell-shaped chordoma and reviewed the appropriate literature. Case Description: A 62-year-old male presented with a three-month history of thoracic pain. When the thoracolumbar magnetic resonance (MR) showed a T3-T4 dumbbell-shaped intracanalicular/extradural tumor, he underwent tumor removal. After the histological examination proved the lesion was a spinal chordoma, he underwent a secondary radical transthoracic tumor resection. Postoperatively, the patient was able to walk without assistance, and at 6-month follow-up, was neu…