Alternative correlations of two-phase friction pressure drop and void fraction are explored for mini-channels based on the separated flow model and drift-flux model. By applying the artificial neural ...network, dominant parameters to correlate the two-phase friction multiplier and void fraction are picked out. It is found that in mini-channels the non-dimensional Laplace constant is a main parameter to correlate the Chisholm parameter as well as the distribution parameter. Both previous correlations and the newly developed correlations are extensively evaluated with a variety of data sets collected from the literature.
In view of practical significance of a correlation of heat transfer coefficient in the aspects of such applications as engineering design and prediction, some efforts towards correlating flow boiling ...heat transfer coefficients for mini-channels have been made in this study. Based on analyses of existing experimental investigations of flow boiling, it was found that liquid-laminar and gas-turbulent flow is a common feature in many applications of mini-channels. Traditional heat transfer correlations for saturated flow boiling were developed for liquid-turbulent and gas-turbulent flow conditions and thus may not be suitable in principle to be used to predict heat transfer coefficients in mini-channels when flow conditions are liquid-laminar and gas-turbulent. By considering flow conditions (laminar or turbulent) in the Reynolds number factor
F and single-phase heat transfer coefficient
h
sp, the Chen correlation has been modified to be used for four flow conditions such as liquid-laminar and gas-turbulent one often occurring in mini-channels. A comparison of the newly developed correlation with various existing data for mini-channels shows a satisfactory agreement. In addition, an extensive comparison of existing general correlations with databases for mini-channels has also been made.
Summary
Background
Microthrombosis and reactive inflammation contribute to neuronal injury after subarachnoid hemorrhage (SAH). ADAMTS‐13 cleaves von Willebrand factor multimers, and inhibits ...thrombus formation and, seemingly, inflammatory reactions.
Objective
To investigate the effect of ADAMTS‐13 in experimental SAH.
Methods
A total of 100 male C57/BL6 mice were randomly assigned to four groups: sham (n = 15), SAH (n = 27), vehicle (n = 25), and ADAMTS‐13 (n = 23; 100 μL per 10 g of body weight of 100 μg of ADAMTS‐13 per 1 mL of 0.9% NaCl; 20 min after SAH). Neurologic performance was assessed on days 1 and 2 after SAH. Animals were killed on day 2. The amounts of subarachnoid blood, microthrombi, apoptosis and degenerative neurons were compared. The degree of neuronal inflammation and vasospasm was also compared. In five mice each (SAH and ADAMTS‐13 groups), bleeding time was assessed 2 h after SAH.
Results
Systemic administration of ADAMTS‐13 achieved significant amelioration of microthrombosis and improvement in neurologic performance. ADAMTS‐13 reduced the amount of apoptotic and degenerative neurons. A tendency for decreased neuronal inflammation was observed. ADAMTS‐13 did not show any significant effect on vasospasm. The degree of systemic inflammation was not changed by ADAMTS‐13 administration. ADAMTS‐13 neither increased the amount of subarachnoid blood nor prolonged the bleeding time.
Conclusions
ADAMTS‐13 may reduce neuronal injury after SAH by reducing microthrombosis formation and neuronal inflammation, thereby providing a new option for mitigating the severity of neuronal injury after SAH.
We report on our efforts to optimize the geometry of neutron moderators and converters for the TRIUMF UltraCold Advanced Neutron (TUCAN) source using MCNP simulations. It will use an existing ...spallation neutron source driven by a 19.3kW proton beam delivered by TRIUMF’s 520MeV cyclotron. Spallation neutrons will be moderated in heavy water at room temperature and in liquid deuterium at 20K, and then superthermally converted to ultracold neutrons in superfluid, isotopically purified 4He. The helium will be cooled by a 3He fridge through a 3He–4He heat exchanger.
The optimization took into account a range of engineering and safety requirements and guided the detailed design of the source. The predicted ultracold-neutron density delivered to a typical experiment is maximized for a production volume of 27L, achieving a production rate of 1.4 ⋅ 107s−1 to 1.6 ⋅ 107s−1 with a heat load of 8.1W. At that heat load, the fridge can cool the superfluid helium to 1.1K, resulting in a storage lifetime for ultracold neutrons in the source of about 30s. The most critical performance parameters are the choice of cold moderator and the volume, thickness, and material of the vessel containing the superfluid helium.
The source is scheduled to be installed in 2021 and will enable the TUCAN collaboration to measure the electric dipole moment of the neutron with a sensitivity of 10−27ecm.
Purpose
This study aimed to compare perioperative outcomes of robotic and laparoscopic transabdominal peritoneal repair (TAPP) for unilateral inguinal hernia.
Methods
This single institutional ...retrospective cohort study used de-identified data of patients who underwent robotic TAPP (R-TAPP) or laparoscopic TAPP (L-TAPP) for unilateral inguinal hernia between January 1, 2016 and October 31, 2021. Two cohorts were propensity matched, and data were analyzed. The learning curve was evaluated in the R-TAPP group.
Results
Among 938 patients analyzed, 704 were included. After propensity-score matching, 80 patients were included in each group. The difference in operative time between R-TAPP and L-TAPP groups was 10 min (99.5 and 89.5 min,
p
= 0.087); however, console/laparoscopic time was similar (67 and 66 min,
p
= 0.71). The dissection time for medial-type hernia in the R-TAPP group was marginally shorter than that in the L-TAPP group (17 and 27 min,
p
= 0.056); however, there was no difference for lateral-type hernia (38.5 and 40 min
p
= 0.37). Perioperative variables, including estimated blood loss, postoperative hospital stay, and postoperative pain, had no significant difference, and chronic pain, which needed medication or intervention, was not observed in each group. The number of cases needed to achieve plateau performance was 7–10 in the R-TAPP group.
Conclusion
This study suggests that R-TAPP was safely introduced, and its perioperative outcomes were not inferior to those of L-TAPP. A shorter dissection time for medial-type hernia might be due to the robot’s advantages, and a fast-learning curve could help with the early standardization of the procedure.
Abstract
Study objectives
Niemann-Pick type C (NPC) is an autosomal recessive and congenital neurological disorder characterized by the accumulation of cholesterol and glycosphingolipids. Symptoms ...include hepatosplenomegaly, vertical supranuclear saccadic palsy, ataxia, dystonia, and dementia. Some cases frequently display narcolepsy-like symptoms, including cataplexy which was reported in 26% of all NPC patients and was more often recorded among late-infantile onset (50%) and juvenile onset (38%) patients. In this current study, we examined CSF orexin levels in the 10 patients of NPC with and without cataplexy, which supports previous findings.
Methods
Ten patients with NPC were included in the study (5 males and 5 females). NPC diagnosis was biochemically confirmed in all 10 patients, from which 8 patients with NPC1 gene were identified. We compared CSF orexin levels among NPC, narcoleptic and idiopathic hypersomnia patients.
Results
Six NPC patients with cataplexy had low or intermediate orexin levels. In 4 cases without cataplexy, their orexin levels were normal. In 5 cases with Miglustat treatment, their symptoms stabilized or improved. For cases without Miglustat treatment, their conditions worsened generally. The CSF orexin levels of NPC patients were significantly higher than those of patients with narcolepsy-cataplexy and lower than those of patients with idiopathic hypersomnia, which was considered as the control group with normal CSF orexin levels.
Discussion
Our study indicates that orexin level measurements can be an early alert of potential NPC. Low or intermediate orexin levels could further decrease due to reduction in the neuronal function in the orexin system, accelerating the patients’ NPC pathophysiology. However with Miglustat treatment, the orexin levels stabilized or improved, along with other general symptoms. Although the circuitry is unclear, this supports that orexin system is indeed involved in narcolepsy-cataplexy in NPC patients.
Conclusion
The NPC patients with cataplexy had low or intermediate orexin levels. In the cases without cataplexy, their orexin levels were normal. Our study suggests that orexin measurements can serve as an early alert for potential NPC; furthermore, they could be a marker of therapy monitoring during a treatment.
A new type of cold/ultracold neutron detector that can realize a spatial resolution of less than 100 nm was developed using nuclear emulsion. The detector consists of a fine-grained nuclear emulsion ...coating and a 50-nm thick
10
B
4
C
layer for the neutron conversion. The detector was exposed to cold and ultracold neutrons (UCNs) at the J-PARC. Detection efficiencies were measured as (0.163 ± 0.015 (stat) ± 0.013 (sys))% and (10.3 ± 1.3 (stat) ± 1.1 (sys))% for cold and ultracold neutrons consistently with the
10
B content in the converter. Positions of individual neutrons can be determined by observing secondary particle tracks recorded in the nuclear emulsion. The spatial resolution of incident neutrons were found to be in the range of 11–99 nm in the angle region of tan
θ
≤
1.9
, where
θ
is the angle between a recorded track and the normal direction of the converter layer. The achieved spatial resolution corresponds to the improvement of one or two orders of magnitude compared with conventional techniques and it is comparable with the wavelength of UCNs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In view of practical significance of a correlation of critical heat flux (CHF) in the aspects of engineering design and prediction, this study is aiming at evaluation of existing CHF correlations for ...flow boiling of water with available databases taken from small-diameter tubes, and then development of a new, simple CHF correlation. Available CHF databases in the literature for flow boiling of water in small-diameter tubes (0.33
<
D
h
<
6.22
mm) are collected, covering wide parametric ranges. Three correlations by Bowring, Katto and Shah are evaluated with the CHF data for saturated flow boiling, and three correlations by Inasaka–Nariai, Celata et al. and Hall–Mudawar evaluated with the CHF data for subcooled flow boiling. The Hall–Mudawar correlation and the Shah correlation seem to be the most reliable tools for CHF prediction in the subcooled and saturated flow boiling regions, respectively. In order to avoid the defect of predictive discontinuities often encountered when applying previous correlations, a simple, nondimensional, inlet conditions dependent CHF correlation for saturated flow boiling has been formulated. Its functional form is determined by the application of the artificial neural network and parametric trend analyses to the collected database. Superiority of this correlation has been verified by the database. The new correlation has a mean deviation of 16.8% for this collected databank, smallest among all tested correlations. Compared to many inordinately complex correlations, this new correlation consists only of a single equation.
Background and Objective
The jaw bone, unlike most other bones, is derived from neural crest stem cells, so we hypothesized that it may have different characteristics to bones from other parts of the ...body, especially in the nature of its periosteum. The periosteum exhibits osteogenic potential and has received considerable attention as a grafting material for the repair of bone and joint defects.
Material and Methods
Gene expression profiles of jaw bone and periosteum were evaluated by DNA microarray and real‐time polymerase chain reaction. Furthermore, we perforated an area 2 mm in diameter on mouse frontal and parietal bones. Bone regeneration of these calvarial defects was evaluated using microcomputed tomography and histological analysis.
Results
The DNA microarray data revealed close homology between the gene expression profiles within the ilium and femur. The gene expression of Wnt‐1, SOX10, nestin, and musashi‐1 were significantly higher in the jaw bone than in other locations. Microcomputed tomography and histological analysis revealed that the jaw bone had superior bone regenerative abilities than other bones.
Conclusion
Jaw bone periosteum exhibits a unique gene expression profile that is associated with neural crest cells and has a positive influence on bone regeneration when used as a graft material to repair bone defects. A full investigation of the biological and mechanical properties of jaw bone as an alternative graft material for jaw reconstructive surgery is recommended.
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