108 research outputs found
Finite element modeling of machining nickel superalloy produced by direct energy deposition process
Vertebral artery dissection in term pregnancy after cervical spine manipulation: a case report and review the literature
Background: Vertebral artery dissection is an uncommon, but potentially fatal, vascular event. This case aimed to describe the pathogenesis and clinical presentation of vertebral artery dissection in a term pregnant patient. Moreover, we focused on the differential diagnosis, reviewing the available evidence. Case presentation: A 39-year-old Caucasian woman presented at 38 + 4 weeks of gestation with a short-term history of vertigo, nausea, and vomiting. Symptoms appeared a few days after cervical spine manipulation by an osteopathic specialist. Urgent magnetic resonance imaging of the head was obtained and revealed an ischemic lesion of the right posterolateral portion of the brain bulb. A subsequent computed tomography angiographic scan of the head and neck showed a right vertebral artery dissection. Based on the correlation of the neurological manifestations and imaging findings, a diagnosis of vertebral artery dissection was established. The patient started low-dose acetylsalicylic acid and prophylactic enoxaparin following an urgent cesarean section. Conclusion: Vertebral artery dissection is a rare but potential cause of neurologic impairments in pregnancy and during the postpartum period. It should be considered in the differential diagnosis for women who present with headache and/or vertigo. Women with a history of migraines, hypertension, or autoimmune disorders in pregnancy are at higher risk, as well as following cervical spine manipulations. Prompt diagnosis and management of vertebral artery dissection are essential to ensure favorable outcomes
2D FE Prediction of Surface Alteration of Inconel 718 under Machining Condition
Abstract Nickel-based super alloys such as Inconel 718 are widely employed in extremely hostile applications owing to their superior thermo-mechanical properties. On the contrary, these latter lead the industries to adopt conservative process parameters (e.g. low cutting speed) resulting in lower production rates. The possibility to increase the cutting parameters could lead to higher material removal rates and drastic reduction of the machining time of the process. The aim of this study is to investigate the effects of extreme cutting parameters on the surface and subsurface alterations such as grain size and hardness changes by developing a finite element (FE) numerical model. The Zener-Hollomon and Hall-Petch equation were implemented to predict the grain size and micro hardness variations due to the cutting process. In addition, the depth of the affected layer due to machining was predicted using the critical strain equation. The obtained results proved the accuracy and reliability of the proposed FE model showing a good agreement between the simulated and the experimental results
Relocation consequences on an ophthalmology consultation service from an inpatient to outpatient facility
Importance This study shows that relocation of an academic ophthalmology residency program from an inpatient to an outpatient setting in western New York does not affect the consult volume but affects management patterns and follow-up rates. Objective To investigate the effects on the ophthalmology consultation service of an academic program with relocation from a Regional Level-1 Trauma center to an outpatient facility. Design Consultation notes from 3 years before and 3 years after the University at Buffalo’s (UB) Department of Ophthalmology relocation from a Regional Level-1 Trauma center (Erie County Medical Center) to an outpatient facility (Ross Eye Institute) were obtained from hospital electronic medical records and analyzed. Setting Hospitalized care and institutional practice. Participants All inpatient or Emergency Room Ophthalmology consultation patients from the Department of Ophthalmology at UB from 2004 to 2010 (1,379 patients). Exposures None, this was a retrospective chart review. Main outcome measures Patient demographics, reason for consult, diagnoses, and ophthalmic procedures performed by the UB Department of Ophthalmology before and after its relocation. Results Relocation to the outpatient facility did not affect consult volume (P=0.15). The number of consults focusing on ophthalmic conditions, as a percentage of the yearly total, rose 460% (P=0.0001), while systemic condition consults with ocular manifestations fell 83% (P=0.0001). Consults for ocular trauma decreased 65% (P=0.0034). Consults ending with a diagnosis of “normal exam” fell, as a percentage of the yearly total (56%, P=0.0023), while diagnoses of new ocular conditions rose 17% (P=0.00065). The percentage of consults for Medicaid patients fell 12% (P=0.0001), while those for privately insured patients rose 15% (P=0.0001). The number of ophthalmic procedures did not change, but postconsult patient follow-up fell from 23% at the Erie County Medical Center clinic to 2% after the move to Ross Eye Institute, a ≥97% decrease. Conclusion and relevance Relocation of UB’s academic Ophthalmology program from an inpatient department to an outpatient facility had no effect on its consultation patient or procedure volume, but it significantly affected the nature of consult diagnoses and decreased outpatient follow-up by \u3e90% at the latter location. Many hospitals are creating separate outpatient facilities that may experience similar obstacles
Polycaprolactone multicore-matrix particle for the simultaneous encapsulation of hydrophilic and hydrophobic compounds produced by membrane emulsification and solvent diffusion processes
Co-encapsulation of drugs in the same carrier, as well as the development of microencapsulation processes for biomolecules using mild operating conditions, and the production of particles with tailored size and uniformity are major challenges for encapsulation technologies. In the present work, a suitable method consisting of the combination of membrane emulsification with solvent diffusion is reported for the production of multi-core matrix particles with tailored size and potential application in multi-therapies. In the emulsification step, the production of a W/O/W emulsion was carried out using a batch Dispersion Cell for formulation testing and subsequently a continuous azimuthally oscillating membrane emulsification system for the scaling-up of the process to higher capacities. In both cases precise and gentle control of droplet size and uniformity of the W/O/W emulsion was achieved, preserving the encapsulation of the drug model within the droplet. Multi-core matrix particles were produced in a post emulsification step using solvent diffusion. The compartmentalized structure of the multicore-matrix particle combined with the different chemical properties of polycaprolactone (matrix material) and fish gelatin (core material) was tested for the simultaneous encapsulation of hydrophilic (copper ions) and hydrophobic (α-tocopherol) test components. The best operating conditions for the solidification of the particles to achieve the highest encapsulation efficiency of copper ions and α-tocopherol of 99 (±4)% and 93(±6)% respectively were found. The multi-core matrix particle produced in this work demonstrates good potential as a co-loaded delivery system
Atypical presentation of acute idiopathic megacolon in a 14-year-old patient
In clinical practice the term "megacolon" is used to indicate a marked dilatation of the cecum and the sigmoid colon (>12 and 6.5 cm, respectively) (1). From a clinical standpoint, a megacolon can be classified as chronic or acute depending on its clinical presentation. Chronic megacolon typically refers to a congenital disorder in which the enteric nervous system (ENS) supplying the colon does not develop properly, thereby leaving the distal segments of the viscus without myenteric and submucosal ganglia (i.e. Hirschsprung's disease) (2). Other cases of non-aganglionic chronic megacolon can be secondary to variety of conditions such as Chagas' disease and neurodegenerative diseases (e.g. Parkinson's and Alzheimer's diseases), leading to or associated with ENS abnormalities (3). The acute form of megacolon, also referred to as Ogilvie's syndrome, is characterized by a predominant involvement of the cecum and right colon usually affecting elderly patients undergoing surgery (e.g. orthopedic procedures) or taking medications altering gut motility (e.g. opioids or antidepressants) (4). Some forms of acute megacolon, however, can be idiopathic in origin since no underlying etiology can be identified. Patients with acute idiopathic megacolon usually have a longstanding history of constipation, often accompanied by laxative abuse, and their clinical presentation is characterized by abdominal distension and severe pain with radiological evidence of stool impacted in the colon and rectum (1, 4). The case herein reported represents an unusual form of acute idiopathic megacolon characterized by massive descending and sigmoid colon distension complicated with a volvulus in a 14-year-old boy with no Hirschsprung's disease. In addition, just to increase the peculiarity of this case report, the patient had an unremarkable clinical record, and never suffered from chronic constipation in the past
Machining and heat treatment as post-processing strategies for Ni-superalloys structures fabricated using direct energy deposition
The aim of this study is to determine the most suitable post-processing routines to enhance the surface integrity of components produced with Inconel 718 superalloy by additive manufacturing. The components were fabricated by Direct Energy Deposition (DED) followed by two typical post-processing methods: machining and heat treatment. The effect of the post-processing sequence (machining + heat treatment or heat treatment + machining) and the corresponding effects on the surface integrity of these components were investigated in terms of surface finishing, microstructure, micro-hardness and residual stresses. Finally, suitable solutions in terms of additive manufacturing - post-process operations have been reported
Probing the nature of the low state in the extreme ultraluminous X-ray pulsar NGC 5907 ULX1
NGC 5907 ULX1 is the most luminous ultra-luminous X-ray pulsar (ULXP) known
to date, reaching luminosities in excess of 1e41 erg/s. The pulsar is known for
its fast spin-up during the on-state. Here, we present a long-term monitoring
of the X-ray flux and the pulse period between 2003-2022. We find that the
source was in an off- or low-state between mid-2017 to mid-2020. During this
state, our pulse period monitoring shows that the source had spun down
considerably. We interpret this spin-down as likely being due to the propeller
effect, whereby accretion onto the neutron star surface is inhibited. Using
state-of-the-art accretion and torque models, we use the spin-up and spin-down
episodes to constrain the magnetic field. For the spin-up episode, we find
solutions for magnetic field strengths of either around 1e12G or 1e13G,
however, the strong spin-down during the off-state seems only to be consistent
with a very high magnetic field, namely, >1e13G. This is the first time a
strong spin-down is seen during a low flux state in a ULXP. Based on the
assumption that the source entered the propeller regime, this gives us the best
estimate so far for the magnetic field of NGC 5907 ULX1.Comment: 10 pages, 1 figure, accepted for publication in A&
A soft and transient ultraluminous X-ray source with 6-h modulation in the NGC 300 galaxy
We investigate the nature of CXOU J005440.5-374320 (J0054), a peculiar bright
( erg/s) and soft X-ray transient in the spiral galaxy
NGC 300 with a 6-hour periodic flux modulation that was detected in a 2014
Chandra observation. Subsequent observations with Chandra and XMM-Newton, as
well as a large observational campaign of NGC 300 and its sources performed
with the Swift Neil Gehrels Observatory, showed that this source exhibits
recurrent flaring activity: four other outbursts were detected across 8
years of monitoring. Using data from the Swift/UVOT archive and from the
XMM-Newton/OM and Gaia catalogues, we noted the source is likely associated
with a bright blue optical/ultraviolet counterpart. This prompted us to perform
follow-up observations with the Southern African Large Telescope in December
2019. With the multi-wavelength information at hand, we discuss several
possibilities for the nature of J0054. Although none is able to account for the
full range of the observed peculiar features, we found that the two most
promising scenarios are a stellar-mass compact object in a binary system with a
WolfRayet star companion, or the recurrent tidal stripping of a stellar
object trapped in a system with an intermediate-mass ( )
black hole.Comment: 13 pages, 11 Figures, 3 Tables (the Table in appendix A will be
available in the published version). Accepted for publication in A&
Synergism through WEE1 and CHK1 inhibition in acute lymphoblastic leukemia
Introduction: Screening for synthetic lethality markers has demonstrated that the inhibition of the cell cycle checkpoint kinases WEE1 together with CHK1 drastically affects stability of the cell cycle and induces cell death in rapidly proliferating cells. Exploiting this finding for a possible therapeutic approach has showed efficacy in various solid and hematologic tumors, though not specifically tested in acute lymphoblastic leukemia. Methods: The efficacy of the combination between WEE1 and CHK1 inhibitors in B and T cell precursor acute lymphoblastic leukemia (B/T-ALL) was evaluated in vitro and ex vivo studies. The efficacy of the therapeutic strategy was tested in terms of cytotoxicity, induction of apoptosis, and changes in cell cycle profile and protein expression using B/T-ALL cell lines. In addition, the efficacy of the drug combination was studied in primary B-ALL blasts using clonogenic assays. Results: This study reports, for the first time, the efficacy of the concomitant inhibition of CHK1/CHK2 and WEE1 in ALL cell lines and primary leukemic B-ALL cells using two selective inhibitors: PF-0047736 (CHK1/CHK2 inhibitor) and AZD-1775 (WEE1 inhibitor). We showed strong synergism in the reduction of cell viability, proliferation and induction of apoptosis. The efficacy of the combination was related to the induction of early S-phase arrest and to the induction of DNA damage, ultimately triggering cell death. We reported evidence that the efficacy of the combination treatment is independent from the activation of the p53-p21 pathway. Moreover, gene expression analysis on B-ALL primary samples showed that Chek1 and Wee1 are significantly co-expressed in samples at diagnosis (Pearson r = 0.5770, p = 0.0001) and relapse (Pearson r= 0.8919; p = 0.0001). Finally, the efficacy of the combination was confirmed by the reduction in clonogenic survival of primary leukemic B-ALL cells. Conclusion: Our findings suggest that the combination of CHK1 and WEE1 inhibitors may be a promising therapeutic strategy to be tested in clinical trials for adult ALL
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