The effect of spacer grid critical component on pressure drop under both single and two phase flow conditions

As pressure drop is one of the most critical thermal hydraulic parameters for spacer grids the accurate estimation of it is the key to the design and development of spacer grids. Most of the available correlations for pressure drop do not contain any real geometrical parameters that characterize the grid effect. The main functions for spacer grid are structural support and flow mixing. Once the boundary sublayer near the rod bundle is disturbed, the liquid forms swirls or flow separation that affect pressure drop. However, under two phase flow conditions, due to the existence of steam bubble, the complexity for spacer grid are multiplied and pressure drop calculation becomes much more challenging. The influence of the dimple location, distance of mixing vane to the nearest strip, and the effect of inter-subchannel mixing among neighboring subchannels on pressure drop and downstream flow fields are analyzed in this paper. Based on this study, more detailed space grid geometry parameters are recommended for adding into the correlation when predicting pressure drop.

CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies

The thermal hydraulic characteristics of a mixing vane grid are largely dependent on the structure of key components, such as strip, spring, dimple, weld nugget, as well as the mixing vane configuration. In this paper, several types of spacer grids with different dimple shapes are modeled under subcooled boiling conditions. Prior to the application of CFD on the dimple shape analysis, the mixing effects of spacer grids were studied. After the dimple shape analysis, the side channel effect is discussed by comparing the simulation results of a 3 × 3 and a 5 × 5 spacer grid. The two phase flow CFD models in this study are validated through simple geometry showing that the calculated void fraction is in good agreement with the experimental data. The dimple comparison result shows that varying dimple structures can result in different temperatures, lateral velocities and void fraction distributions downstream of the spacer grids. Comparison of two sizes of spacer grids demonstrate that the side channel generates different flow distribution pattern in the center channel.

A novel laser-collider used to produce monoenergetic 13.3 MeV (7)Li (d, n) neutrons

Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel "laser-collider" method was used at the Shenguang II laser facility to produce monoenergetic neutrons via (7)Li (d, n) nuclear reactions. The specially designed K-shaped target significantly increased the numbers of incident d and Li ions at the keV level. Ultimately, 13.3 MeV neutrons were obtained. Considering the time resolution of the neutron detector, we demonstrated that the produced neutrons were monoenergetic. Interferometry and a Multi hydro-dynamics simulation confirmed the monoenergetic nature of these neutrons.

Trefoil factor 3 related to gastrointestinal failure in pediatric critical illness

BACKGROUND

To determine the relationship between the serum concentration of trefoil factor 3 (TFF3) and gastrointestinal failure (GIF) in pediatric critical illness in order to provide knowledge for disease management.

MATERIALS AND METHODS

We enrolled 137 cases and divided them into three groups, including a control group (group A), critical illness without GIF (group B), and critical illness with GIF (group C). The serum TFF3 concentration was determined by ELISA and compared among the groups.

RESULTS

Serum TFF3 concentrations measured before the occurrence of GIF in group C were significantly higher than in groups A and B (P<0.01). Under the conditions of GIF in group C, serum TFF3 concentration was significantly related to the gastrointestinal tract function score (r=-0.712). Cox's proportional hazards model analysis showed that the serum TFF3 concentrations at the time of occurrence of GIF, and 48hours later, could be used as prognostic factors in critically ill pediatric patients with GIF (r=1.443 and 1.872, respectively).

CONCLUSION

TFF3 may play an important role in predicting GIF in pediatric critical illness and has a protective function in the mucosal repair process.

eEF-2 kinase is a critical regulator of Warburg effect through controlling PP2A-A synthesis

Cancer cells predominantly metabolize glucose by glycolysis to produce energy in order to meet their metabolic requirement, a phenomenon known as Warburg effect. Although Warburg effect is considered a peculiarity critical for survival and proliferation of cancer cells, the regulatory mechanisms behind this phenomenon remain incompletely understood. We report here that eukaryotic elongation factor-2 kinase (eEF-2K), a negative regulator of protein synthesis, has a critical role in promoting glycolysis in cancer cells. We showed that deficiency in eEF-2K significantly reduced the uptake of glucose and decreased the productions of lactate and adenosine triphosphate in tumor cells and in the Ras-transformed mouse embryonic fibroblasts. We further demonstrated that the promotive effect of eEF-2K on glycolysis resulted from the kinase-mediated restriction of synthesis of the protein phosphatase 2A-A (PP2A-A), a key factor that facilitates the ubiquitin-proteasomal degradation of c-Myc protein, as knockdown of eEF-2K expression led to a significant increase in PP2A-A protein synthesis and remarkable downregulation of c-Myc and pyruvate kinase M2 isoform, the key glycolytic enzyme transcriptionally activated by c-Myc. In addition, depletion of eEF-2K reduced the ability of the transformed cells to proliferate and enhanced the sensitivity of tumor cells to chemotherapy both in vitro and in vivo. These results, which uncover a role of the eEF-2K-mediated control of PP2A-A in tumor cell glycolysis, provide new insights into the regulation of the Warburg effect.

MicroRNA-92b promotes hepatocellular carcinoma progression by targeting Smad7 and is mediated by long non-coding RNA XIST

MicroRNA (miRNA) and long non-coding RNA (lncRNA) have been demonstrated to participate in the progression of many cancers. Hepatocellular carcinoma (HCC) is one of the most common and aggressive malignant tumors worldwide, while the molecular mechanisms underlying HCC tumorigenesis are not completely clear. In this study, we showed that miR-92b was significantly upregulated in tumor tissue and plasma of HCC patients, and its expression level was highly correlated with gender and microvascular invasion. Functionally, miR-92b could promote cell proliferation and metastasis of HCC in vitro and in vivo. Mechanistic investigations suggested that Smad7, which exhibited an inverse relationship with miR-92b expression in HCC, was a direct target of miR-92b and could reverse its effects on HCC tumorigenesis. Furthermore, long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) and miR-92b could directly interact with and repress each other, and XIST could inhibit HCC cell proliferation and metastasis by targeting miR-92b. Taken together, our study not only revealed for the first time the importance of XIST/miR-92b/Smad7 signaling axis in HCC progression but also suggested the potential value of miR-92b as a biomarker in the clinical diagnosis and treatment of HCC.

High frequency of OTOF mutations in Chinese infants with congenital auditory neuropathy spectrum disorder

Auditory neuropathy spectrum disorder (ANSD) is one of the most common diseases leading to hearing and speech communication barriers in infants and young children. The OTOF gene is the first gene identified for autosomal recessive non-syndromic ANSD, and patients with OTOF mutations have shown marked improvement of auditory functions from the cochlear implantation, but the true involvement of OTOF mutations in Chinese ANSD patients is still unknown which precludes the effective management of this disease. Here, we investigated the contribution of OTOF mutations to congenital ANSD patients in China. In all, 37 infants and young Children with ANSD were screened for all the exons of OTOF gene, of them 34 patients had no neonatal risk factors who were considered as congenital ANSD. The clinical manifestation and audiometric features were also investigated and compared in patients with and without OTOF mutations. In all, 14 of these subjects were shown to carry two or three mutant alleles of OTOF with the high frequency of 41.2% in congenital ANSD patients. In total, 15 novel pathogenic mutations and 10 reported mutations were identified. Our results confirmed that mutations in OTOF gene were a major cause of congenital ANSD in China. Identification of OTOF mutations can facilitate diagnosis, clinical intervention and counseling for congenital ANSD.

MiR-125a promotes paclitaxel sensitivity in cervical cancer through altering STAT3 expression

Cervical cancer (CC) is one of the most common malignancies in women. Paclitaxel is the front-line chemotherapeutic agent for treating CC. However, its therapeutic efficacy is limited because of chemoresistance, the mechanism of which remains poorly understood. Here, we used microRNA (miRNA) arrays to compare miRNA expression levels in the CC cell lines, HeLa and CaSki, with their paclitaxel resistance counterparts, HeLa/PR and CaSki/PR. We demonstrate that miR-125a was one of most significantly downregulated miRNAs in paclitaxel-resistant cells, which also acquired cisplatin resistance. And that the upregulation of miR-125a sensitized HeLa/PR and CaSki/PR cells to paclitaxel both in vitro and in vivo and to cisplatin in vitro. Moreover, we determined that miR-125a increased paclitaxel and cisplatin sensitivity by downregulating STAT3. MiR-125a enhanced paclitaxel and cisplatin sensitivity by promoting chemotherapy-induced apoptosis. Clinically, miR-125a expression was associated with an increased responsiveness to paclitaxel combined with cisplatin and a more favorable outcome. These data indicate that miR-125a may be a useful method to enable treatment of chemoresistant CC and may also provide a biomarker for predicting paclitaxel and cisplatin responsiveness in CC.

Recent performance of and plasma outage studies with the SNS H⁻ source

Spallation Neutron Source ramps to higher power levels that can be sustained with high availability. The goal is 1.4 MW despite a compromised radio frequency quadrupole (RFQ), which requires higher radio frequency power than design levels to approach the nominal beam transmission. Unfortunately at higher power the RFQ often loses its thermal stability, a problem apparently enhanced by beam losses and high influxes of hydrogen. Delivering as much H(-) beam as possible with the least amount of hydrogen led to plasma outages. The root cause is the dense 1-ms long ∼55-kW 2-MHz plasma pulses reflecting ∼90% of the continuous ∼300 W, 13-MHz power, which was mitigated with a 4-ms filter for the reflected power signal and an outage resistant, slightly detuned 13-MHz match. Lowering the H2 gas also increased the H(-) beam current to ∼55 mA and increased the RFQ transmission by ∼7% (relative).

Comparison of vindesine and prednisone and cyclophosphamide, etoposide, vindesine, and prednisone as first-line treatment for adult Langerhans cell histiocytosis: A single-center retrospective study

OBJECTIVE

We compared the efficacy and clinical outcomes of vindesine and prednisone (VP) and cyclophosphamide, etoposide, vindesine, and prednisone (CEVP) regimens as first-line treatment for multisystem (MS) or multifocal single system (SS-m) adult Langerhans cell histiocytosis (LCH).

METHOD

Clinical features, treatment response, and survival of adults with Langerhans cell histiocytosis treated at our center from January 2001 to January 2015 were reviewed retrospectively.

RESULTS

Forty-five adult MS or SS-m LCH patients were treated (N=31, CEVP group; N=14, VP group). Both treatment groups had similar gender distributions, patient ages, and extent of disease. The non-active disease rate for both groups was 70.0% and 64.3% (P=0.775), respectively. Median follow-up was 74.9 (range: 2.8-183.6) months and recurrence rates were 71.0% and 78.6% (P=0.593), respectively. The need for second-line therapy was 64.5% and 71.4% (P=0.649), respectively, and mortality rates were 9.7% and 15.4% (P=0.586), respectively. Neutropenia occurred in 48.4% of CEVP-treated patients and 7.1% of VP-treated patients (P=0.008).

CONCLUSIONS

CEVP or VP regimens for the treatment of adult SS-m or MS LCH showed similar efficacies, and both regimens were associated with high disease recurrence and the need for second-line therapy.

Relationship between B-type natriuretic peptide and short-term prognosis in non-diabetic patients with ST-segment elevation myocardial infarction

OBJECTIVE

To investigate the differences of the B-type natriuretic peptide (BNP) levels in serum or plasma of the STEMI patients with different infarction sites. To explore the relationship between the BNP level and the short-term prognosis in patients with ST-segment elevation myocardial infarction (STEMI).

PATIENTS AND METHODS

A total of 216 STEMI patients were enrolled in this study from June 2012 to June 2014. All patients received coronary angiography (CAG). Based on electrocardiography (ECG) and CAG results, patients were divided into three groups. Group A included 80 patients with anterior/lateral wall myocardial infarction, group B included 76 patients with inferior/posterior wall myocardial infarction and group C included 60 patients with right ventricular myocardial infarction. We enrolled 53 patients with normal CAG results as Group D. BNP levels were compared among these groups. and according to BNP levels, all patients were subdivided into normal BNP group (< 100 ng/mL, n = 53), mild-higher BNP group (100-400 ng/mL, n = 105) and marked-higher BNP group (≥ 400 ng/mL, n = 58). The occurrence of major adverse cardiovascular events (MACE) including secondary heart failure, severe arrhythmia, post-infarction angina, recurrent myocardial infarction, and cardiac death within 6 months after disease onset were assessed.

RESULTS

BNP levels showed a gradually decreasing trend in groups A, B, C and D (p < 0.05). Significant differences in left ventricular ejection fraction (LVEF) were found among normal BNP group, mild-high BNP group and marked-higher BNP group (p < 0.05). The MACE occurrence presented no statistical differences between normal BNP group and mild-higher BNP group (p > 0.05). The MACE prevalence in marked-higher BNP group was significantly higher than normal BNP group and mild-higher BNP group (p < 0.05).

CONCLUSIONS

BNP levels can be used as a clinical indicator to predict short-term prognosis in STEMI patients.

Penehyclidine hydrochloride postconditioning ameliorates cerebral ischemia-reperfusion injury: critical role of mitochondrial ATP sensitive potassium channel

Cerebral ischemia/reperfusion (CI/R) leads to disability and death worldwide. However, limited approaches have been made in developing therapies to decrease the detrimental effects of CI/R. In the present study, we evaluated the effects of penehyclidine hydrochloride (PHC) postconditioning on CI/R injury and elucidated the underlying mechanisms. In CI/R rats, we showed that PHC postconditioning could effectively inhibit I/R-induced brain infarction and edema, and deficit of neurological function. In addition, PHC postconditioning significantly inhibited I/R-induced increase of proinflammatory cytokines and TUNEL-positive cell numbers. Moreover, the opening of mitochondrial permeability transition pore (mPTP) and oxidative stress resulting from I/R were suppressed notably by PHC postconditioning, as evidenced by increased absorbance at 540 nm in Ca2+-induced mitochondrial swelling test and increased SOD activity and decreased ROS and MDA level. 5-hydroxydecanoate (5-HD), a specific inhibitor of MitoKATP, was used to evaluate the role of MitoKATP in the neuroprotective effect of PHC postconditioning. The results showed that 5-HD could markedly suppress PHC postconditioning-caused inhibition of brain infarction and edema, deficit of neurological function, inflammation, apoptosis, opening of mPTP and oxidative stress induced by CI/R. The results demonstrated that PHC postconditioning could protect against I/R injury in brain through the inhibition of oxidative stress, mPTP opening, apoptosis and inflammation. Activation of MitoKATP was critical for PHC postconditioning-exhibited neuro-protective effects against I/R injury. These findings may provide a novel foundation for therapeutic strategies targeting cerebral protection against I/R damage.

A High-sugar High-fat Diet Induced Metabolic Syndrome Shows some Symptoms of Alzheimer's Disease in Rats

OBJECTIVES

Cases of sporadic Alzheimer's disease (SAD) are the predominant form of the age-related dementia. New evidence suggests that metabolic syndrome (MS), a metabolic disorder, is an initiating factor of some SAD cases. A high-sugar high-fat diet could cause MS, we aimed to investigate whether it could directly lead to SAD.

MEASUREMENTS

The characteristic molecules of AD (hippocampus Aβ and Tau) were tested by using ELISA and western blotting to confirm the happening hallmarks of AD in brain. MS and inflammation related biochemical indicators were measured using immunological method. Proteins associated with the insulin resistance signal pathway (JNK, PI-3K, AKT, GSK-3β, GLUT3) were evaluated using western blotting method. The levels of reactive oxygen species (ROS) were measured by immunofluorescence method.

RESULTS

Expressions of hippocampus Aβ, phosphorylation-Tau (p-Tau), inflammatory factors and p-JNK, Gsk-3βwere higher in the model rats than those in the control rats and expressions of p-PI3K, p-AKT and GLUT3 were reversed.

CONCLUSIONS

The MS model animals, which can induce the characteristics symptoms of AD, and therefore it may be preliminarily considered that the AD pertains to the MS-related diseases.

Supplemental lipoic acid relieves post-weaning diarrhoea by decreasing intestinal permeability in rats

Lipoic acid (LA) is a naturally existing substance which widely distributed in the cellular membranes and cytosol of animal cells. Its intracellular functions include quenching of free radicals and repairing oxidized proteins. The purpose of this study was to evaluate the effects of LA on post-weaning diarrhoea using a rat model. Sixty weaned rats were fed either a basal diet or a LA-supplemented diet, or a zinc oxide (ZnO)-supplemented diet as a positive control. Rats in the LA and ZnO groups had better performance and reduced incidence of diarrhoea (p < 0.05). Both LA and ZnO treatments enhanced intestinal homeostatic and architecture, significantly decreased urinary lactulose to mannitol ratios (p < 0.05) and increased the expression of the intestinal mucosal tight junction proteins occludin (OCLN) and zonula occludens protein-1 (ZO-1) (p < 0.05). LA significantly increased the activities of antioxidant enzymes, and reduced glutathione while decreasing the levels of oxidative glutathione and malondialdehyde in the intestinal mucosa (p < 0.05). Furthermore, an in vitro study indicated that supplementation with LA in IEC-6 intestinal epithelial cells significantly enhanced the expression of OCLN and ZO-1 under hydrogen peroxide-induced oxidative stress. Collectively, these results suggest that LA relieves post-weaning diarrhoea by reducing intestinal permeability and improving antioxidant indices.

Circulating miR-125b as a biomarker of Ewing's sarcoma in Chinese children

Previous studies indicated that microRNA-125b (miR-125b) has an important role in the progression of Ewing's sarcoma (ES). The purpose of the current study was to examine expression changes of miR-125b in the serum of ES patients and evaluate if the expression level of miR-125b could serve as a new biomarker for ES. This study was performed on patients who underwent surgical resection at our hospital between 2005 and 2013 after an initial diagnosis of ES. We measured serum miR-125b levels in 63 patients with ES and 126 healthy control patients using a real-time quantitative reverse transcriptase-PCR (qRT-PCR) method. Expression levels of serum miR-125b were distinctly decreased in ES patients when compared with healthy controls (P < 0.001). ES cases that had a poor response to chemotherapy presented a significant down-regulation of miR-125b (P = 0.001). The ROC curve showed that the serum miR-125b could serve as a valuable biomarker for differentiating ES patients from healthy controls with an AUC of 0.879 (95%CI = 0.817-0.924; P < 0.001). At a cut-off value of 2.203 for miR-125b, the sensitivity was 72.8% and the specificity was 87.2% in discriminating ES from the controls. Our results indicate that serum miR- 125b may serve as a useful noninvasive biomarker for ES.