bluuebunny/crossref_metadata_2025_split huggingface dataset:
Centrifugal Pumps in Steam Power Stations
Authors: Pennington R. 
Published: February 2019

Some fundamental and specific hydraulic considerations associated with the operation of centrifugal pumps on condenser cooling-water circulation, condensate extraction and boiler feeding services are discussed and illustrated by simple empirical formulae and practical diagrams. Attention is drawn to the importance of selecting the correct speed for reliable operation. The hydraulic gradient through a pump is represented diagrammatically to illustrate the meaning of the term “depression head” and to show how this is related to the throttling condition. It is claimed that in certain circumstances a pump can operate advantageously and safely on the throttling point, but otherwise it is essential to avoid what is described as the “cavitation area”. A relation is established between pump output, “depression head”, and maximum permissible speed. The “speed coefficient” used in the formula is shown to depend on several factors. For circulating water pumps the relation between “depression head” and suction lift is illustrated. Maximum speed in relation to output and variation of pump type with specific speed and net head are presented graphically. Diagrams and curves show the fundamental difference in operating methods of extraction pumps on the two main types of surface condenser and on de-aerators. Factors influencing the choice of speed are outlined. A typical build-up of the pressure characteristics of a boiler feed system is illustrated and the requirements of the system are compared with the characteristics provided by the feed-pumps, both constant and variable speed. Reference is made to the importance of providing suitable pressure-characteristics to ensure satisfactory parallel operation, load sharing and freedom from pressure surge. A formula is developed for calculation of the temperature rise across a feed-pump at any load, and proposals are outlined for keeping this rise within safe limits. Special reference is made to the feed-pump drawing direct from a de-aerator and the problem of avoiding vapour-locking with sudden fall in pressure. The main factors which determine the operating speed of a feed-pump are enumerated. Attention is drawn to the importance of, and means of constructing, the pump to withstand a sudden reduction in temperature without incurring casing joint leakages. The relative merits of placing the feed-pumps before or after the heaters are discussed, and it is claimed that considerable thermal economy is achieved by using high-pressure heaters.
The Design of Tube Plates in Heat Exchangers
Authors: Miller K. A. G. 
Published: February 2019

Up to the present time designers of heat exchangers have used an empirical method for determining the tube plate thickness. This is based on the formula for the maximum stress in a thin circular plate under uniform loading. It takes no account of the support given to the tube plate by the tubes, and does not attempt to differentiate the weakening effects of different tube hole spacings. In this paper, these two factors are considered. A definite algebraic expression is introduced to cover the weakening effect of the holes, and the support given by the tubes is accounted for by treating the tube plate as a thin circular plate resting on an elastic foundation. This gives rise to fairly complicated mathematics, which are fully set out, but there is no need to refer to the mathematics in the design of a particular tube plate, as the analysis leads to fairly simple design formulae and the procedure for using them is indicated in simple terms. Four familiar types of heat exchanger are considered, and design formulae have been developed for the maximum stress in both the tube plate and the tubes. An experimental test was carried out on the tube plate of an existing heat exchanger, and the results are shown to be in reasonable agreement with the proposed theory. To illustrate the method three examples are worked out, and by comparison of the results with those obtained by the existing method it is shown that a reduction in the thickness of the tube plate can be obtained. The MS. of this paper was first received at the Institution on 20th June 1951, and in its revised form, as accepted for publication by the Council, on 15th November 1951.
Experimental Investigation of Torsion in Stranded Mining Wire Ropes
Authors: Layland C. L. , Rao A. R. S. , Ramsdale H. A. 
Published: February 2019

In this paper an account is given of some investigations into the torsional properties of mining wire ropes, carried out at a gold mine in India by some members of the engineering staff of the mine. An attempt is made to connect some interesting facts which emerged, in such a manner as to make them useful in practice. The work was necessarily confined to four small sizes and only two different constructions, but the results obtained suggest that experiments on larger sizes and other constructions would greatly aid the users of very long, large ropes. Light is thrown on the difference of torsional properties between Lang's lay and ordinary lay, between long and short lay-pitch, and between few and many wires, and a contribution is made to the arguments against deliberately unlaying a new Lang's lay rope.
Control Valves for Direct-hydraulic Presses
Authors: Towler F. H. , Towler J. M. 
Published: February 2019

Some direct-hydraulic presses have become very complicated owing to the introduction of servo-electric controls, embodying a mass of electrical gadgets, solenoids, micro-switches, etc. In this paper a new, completely hydraulic control system is described which entirely replaces the electrical controls, thereby bringing all maintenance problems within the scope of the hydraulic engineer. Also, with the elimination of electrical delays it is possible to ensure almost instantaneous valve action. The paper deals briefly with packingless piston valves, the avoidance of various forms of lock, and the problems involved in the design, construction and control of large hydraulic presses, the choice of the most advantageous working pressure, and the viscosity of the hydraulic oil. A detailed description is given of a 1,000-ton direct-hydraulic forging and planishing press, powered by high-speed pumps totalling 665 pump horse-power and controlled by a single-lever, completely hydraulic, remote-control panel. This press makes reversal in [Formula: see text] second, making short planishing strokes as lively as a pneumatic hammer. In conclusion, controls and multiple power units for much larger presses are discussed.
Measures of Self-Perception, Level of Physical Activity, and Body Mass Index of Participants of Sports Education Camps for Youths with Visual Impairments
Authors: McMahon John , Emerson Robert S. Wall , Ponchillia Paul , Curtis Amy 
Published: February 2019

Introduction: This study explored the relationship between first-time or repeat participation at a sports education camp and demographic variables of gender, age, race or ethnicity, measures of self-perception, body mass index (BMI), and physical activity in participants’ communities. Methods: The study was a secondary data analysis of interview and BMI data for youths with visual impairments (i.e., those who are blind or have low vision) who attended a sports education camp in one of 12 states in the years 1989, 1996, and 2000–2010. Results: The short-term intervention model of a sports education camp had a positive effect on participants’ perceptions of themselves. This result was more pronounced for boys and for youths with some usable vision. Involvement in a sports education camp did not tend to translate to increased involvement in sports in a student’s community. The mean BMI of first-time participants was consistent across gender, race or ethnicity, and vision category, and the BMI of first-time participants tended to be higher according to the age of the participant. Discussion: The findings revealed that the short-term intervention model of a sports education camp is highly effective in increasing self-perception for youngsters with vision impairments. Implications for practitioners: For youths with visual impairments who might be experiencing reduced social interaction, decreased self-perception or increased BMI involvement in a sports education camp is a short-term intervention that can positively impact these effects.
Change in cardiac troponin T level after intravitreal anti-vascular endothelial growth factor treatment: Prospective pilot study
Authors: Rebeiz Abdallah G , Mahfoud Ziyad , Abdul Fattah Maamoun , Saad Alain , Safar Ammar , Bashshur Ziad F 
Published: February 2019

Background: Evaluate subclinical myocardial injury associated with intravitreal anti-vascular endothelial growth factor therapy by measuring serum high-sensitivity cardiac troponin T. Methods: This is a prospective pilot comparative study conducted at American University of Beirut Medical Center, Beirut, Lebanon. In total, 40 consecutive patients were randomized to receive either intravitreal bevacizumab or ranibizumab. Patients received three consecutive monthly injections of the assigned drug, then continued treatment as needed. Systemic concentrations of high-sensitivity cardiac troponin T and vascular endothelial growth factor were obtained at baseline, week 9, and week 24. Primary endpoint measure was change in high-sensitivity cardiac troponin T levels compared to baseline. Secondary endpoint measure was change in systemic vascular endothelial growth factor levels. Results: There was no significant difference in high-sensitivity cardiac troponin T levels over time ( p = 0.227) within each treatment group and no significant difference between treatments at any time point ( p = 0.276). There was a significant decrease in plasma vascular endothelial growth factor levels at week 9 ( p = 0.001) and week 24 ( p < 0.001) compared to baseline. In the ranibizumab group, vascular endothelial growth factor levels were not significantly different at weeks 9 and 24 compared to baseline ( p = 0.708 and p = 0.117, respectively). There was a significant association between the number of bevacizumab injections from weeks 8 to 24 and the decrease in vascular endothelial growth factor levels at week 24 ( R = −0.67, p = 0.032). This correlation was not observed in the ranibizumab group ( R = −0.341, p = 0.141). Conclusion: Repeated intravitreal bevacizumab or ranibizumab did not influence serum high-sensitivity cardiac troponin levels. Intravitreal bevacizumab but not ranibizumab lowered free-systemic vascular endothelial growth factor levels, which was observed in this study to be inversely related to the number of bevacizumab injections.
Expression of platelet-derived growth factor-C in aqueous humor of patients with neovascular glaucoma and its correlation with vascular endothelial growth factor
Authors: Li Yujie , Hu Dan , Lv Peilin , Xing Minyan , Song Zejuan , Li Chan , Wang Yusheng , Hou Xu 
Published: February 2019

Aim: The aim of this study was to investigate the expression of platelet-derived growth factor-C in aqueous humor of patients with neovascular glaucoma and its correlation with vascular endothelial growth factor. Methods: This study involved 62 eyes of 62 patients with advanced neovascular glaucoma requiring transscleral cyclophotocoagulation. Aqueous humor was collected through paracentesis. Samples from 11 eyes of 11 patients with age-related cataract were collected as control. Concentrations of platelet-derived growth factor-C and vascular endothelial growth factor in aqueous humor were quantified by enzyme-linked immunosorbent assay. Meanwhile, the correlations between the concentrations of platelet-derived growth factor-C and vascular endothelial growth factor were analyzed. The elements including retinal photocoagulation treatment, iris neovascularization grade, and primary fundus disease were also studied to find out their roles in the concentrations of the two factors. Results: The vascular endothelial growth factor and platelet-derived growth factor-C concentrations in aqueous humor from controls were (679.54 ± 49.81) pg/mL and (18.60 ± 1.85) pg/mL, respectively. Both of them were significantly lower than neovascular glaucoma patients ( p < 0.001). The vascular endothelial growth factor and platelet-derived growth factor-C concentrations of neovascular glaucoma patients treated with retinal photocoagulation were (1095.99 ± 52.71) pg/mL and (28.55 ± 0.94) pg/mL, respectively, which were both significantly lower than those of untreated neovascular glaucoma patients, (1146.28 ± 69.57) pg/mL and (30.04 ± 1.64) pg/mL ( p = 0.008, p = 0.034). There was a weak correlation between the expression level of vascular endothelial growth factor and platelet-derived growth factor-C in aqueous humor with neovascular glaucoma ( r = 0.346, p = 0.006). However, iris neovascularization grade and primary fundus disease were not significant elements in the expression level of vascular endothelial growth factor and platelet-derived growth factor-C. Conclusion: Higher concentrations of vascular endothelial growth factor and platelet-derived growth factor-C were found in aqueous humor of patients with neovascular glaucoma compared with control, which could be lowered by retinal photocoagulation to some extent. Platelet-derived growth factor-C inhibitors may be another potential target for ocular neovascular diseases.
The feasibility of online video calling to engage patients with cystic fibrosis in exercise training
Authors: Tomlinson Owen W , Shelley James , Trott Jayne , Bowhay Ben , Chauhan Rohan , Sheldon Christopher D 
Published: February 2019

Introduction Physical activity, including structured exercise, is an essential component in the management of cystic fibrosis. The use of telehealth such as video-calling may be a useful method for the delivery of exercise and physical activity interventions, though the feasibility of this remains unknown. Methods Nine patients with cystic fibrosis (three female, six male, 30.9 ± 8.7 years) volunteered to participate. Participants completed an eight-week exercise training intervention conducted via Skype, using personalised exercises, with all sessions supervised by an exercise therapist. Feasibility was assessed by demand, implementation, practicality and acceptability. Changes in anthropometric, pulmonary, physical activity and quality of life variables were also assessed. Results Two male participants withdrew from the study, citing lack of available time. The remaining participants found use of Skype useful, with a mean satisfaction rating of 9/10, and three participants requesting to continue the sessions beyond the duration of the study. Mean compliance with sessions was 68%, with mean duration of sessions being 20 min. A total of 25% of calls suffered from technical issues such as video or audio lags. Anthropometric, pulmonary, physical activity and quality of life variables remained unchanged over the course of the study period. Discussion The use of Skype to deliver an exercise intervention to patients withcystic fibrosis was found to be technologically feasible, and acceptable among participants. Findings have implications for clinical practice and could allow care teams to engage patients remotely in exercise. Further research is required to assess the efficacy of this modality on increasing physical activity and associated health outcomes.
Prognostic value of ALDH1 and Nestin in advanced cancer: a systematic meta-analysis with trial sequential analysis
Authors: Han Susu , Huang Tao , Wu Xing , Wang Xiyu , Li Wen , Liu Shanshan , Yang Wei , Shi Qi , Li Hongjia , Shi Kunhe , Hou Fenggang 
Published: February 2019

Background: Novel prognostic markers and therapeutic targets for advanced cancer are urgently needed. This report with trial sequential analysis (TSA) was first conducted to provide robust estimates of the correlation between aldehyde dehydrogenase 1 (ALDH1) and Nestin and clinical outcomes of advanced cancer patients. Methods: Hazard ratios (HRs) with 95% confidence intervals (CIs) were summarized for overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), cancer-specific survival (CSS), relapse/recurrence-free survival (RFS), and metastasis-free survival (MFS) from multivariable analysis. TSA was performed to control for random errors. Results: A total of 20 studies with 2050 patients (ALDH1: 15 studies with 1557 patients and Nestin: 5 studies with 493 patients) were identified. ALDH1 (HR = 2.28, p < 0.001) and Nestin (HR = 2.39, p < 0.001) were associated with a worse OS, as confirmed by TSA. Nestin positivity was linked to a poor PFS (HR = 2.08, p < 0.001), but ALDH1 was not linked to DFS, RFS, MFS, or PFS, and TSA showed that more studies were needed. Subgroup analysis by tumor type indicated that ALDH1 positivity may be associated with shorter OS in breast, head and neck cancers, but there was no association with colorectal cancer. Subgroup analysis by study source showed that ALDH1 positivity was correlated with a worse OS for Japanese (HR = 1.94, p = 0.002) and European patients (HR = 4.15, p < 0.001), but there was no association for Chinese patients. Subgroup analysis by survival rate showed that ALDH1 positivity correlated with poor OS at ⩾ 5 years (HR = 2.33, p < 0.001) or 10 years (HR = 1.76, p = 0.038). Conclusions: ALDH1 may be more valuable as an effective therapeutic target than Nestin for improving the long-term survival rate of advanced cancer. Additional prospective clinical trials are needed across different cancer types.
Hypoxia‐induced pulmonary hypertension and chronic lung disease: caveolin‐1 dysfunction an important underlying feature
Authors: Huang Jing , Frid Maria , Gewitz Michael H. , Fallon John T. , Brown Dale , Krafsur Greta , Stenmark Kurt , Mathew Rajamma 
Published: February 2019

Caveolin‐1 (cav‐1) has been shown to play a significant role in the pathogenesis of pulmonary hypertension (PH). In the monocrotaline model of PH, the loss of endothelial cav‐1 as well as reciprocal activation of proliferative and anti‐apoptotic pathways initiate the disease process and facilitate its progression. In order to examine the role of cav‐1 in hypoxia‐induced PH, we exposed rats and neonatal calves to hypobaric hypoxia and obtained hemodynamic data and assessed the expression of cav‐1 and related proteins eNOS, HSP90, PTEN, gp130, PY‐STAT3, β‐catenin, and Glut1 in the lung tissue. Chronic hypoxic exposure in rats (48 h–4 weeks) and calves (2 weeks) did not alter the expression of cav‐1, HSP90, or eNOS. PTEN expression was significantly decreased accompanied by PY‐STAT3 activation and increased expression of gp130, Glut1, and β‐catenin in hypoxic animals. We also examined cav‐1 expression in the lung sections from steers with chronic hypoxic disease (Brisket disease) and from patients with chronic lung disease who underwent lung biopsy for medical reasons. There was no cav‐1 loss in Brisket disease. In chronic lung disease cases, endothelial cav‐1 expression was present, albeit with less intense staining in some cases. In conclusion, hypoxia did not alter the cav‐1 expression in experimental models. The presence of cav‐1, however, did not suppress hypoxia‐induced activation of PY‐STAT3 and β catenin, increased gp130 and Glut1 expression, or prevent the PTEN loss, indicating cav‐1 dysfunction in hypoxia‐induced PH.
Parameters associated with outcome in pediatric patients with congenital heart disease and pulmonary hypertension subjected to combined vasodilator and surgical treatments
Authors: Thomaz Ana Maria , Kajita Luiz J. , Aiello Vera D. , Zorzanelli Leína , Galas Filomena Regina B.G. , Machado Cleide G. , Barbero‐Marcial Miguel , Jatene Marcelo B. , Rabinovitch Marlene , Lopes Antonio Augusto 
Published: February 2019

Management of pediatric pulmonary hypertension associated with congenital heart disease (PHT‐CHD) is challenging. Some patients have persistently elevated pulmonary artery pressure (PAP) after cardiac surgery, an undesired condition that is difficult to predict. We investigated the value of clinical, hemodynamic, and histopathological data in predicting the outcome in a prospective cohort. Patients with PHT‐CHD received sildenafil orally pre‐ and postoperatively for six months and then were subjected to a catheter study. Thirty‐three patients were enrolled (age range = 4.6–37.0 months). Pulmonary vascular resistance (PVR) was 4.9 (range = 3.9–7.2) Wood units × m2 (median with IQR). Twenty‐two patients had a ≥ 20% decrease in PVR and pulmonary‐to‐systemic vascular resistance ratio (PVR/SVR) in response to inhaled nitric oxide (NO). The response was directly related to the degree of medial hypertrophy of pulmonary arterioles (P < 0.05) (morphometric analysis, intraoperative lung biopsy). Subsequently, five of the non‐responders had a ≥ 30% increase in pulmonary blood flow in response to sildenafil (3.0 [2.0–4.0] mg/kg/day). Six months after surgery, PAP and PVR were significantly lower (P < 0.001 vs. baseline), even in seven patients with Heath‐Edwards grade III/IV pulmonary vascular lesions (P = 0.018), but still abnormal in 12 individuals (>25 mmHg and >3.0 U × m2, respectively). A preoperative PVR/SVR of ≥24% during NO inhalation and a wall thickness of arteries accompanying respiratory bronchioli of ≥4.7 (Z score) were identified, respectively, as risk and protection factors for abnormal postoperative hemodynamics (hazard ratio [95% CI] = 1.09 [1.01–1.18], P = 0.036; and 0.69 [0.49–0.98], P = 0.040, respectively). Thus, in PHT‐CHD patients receiving oral sildenafil pre‐ and post‐surgical repair of cardiac lesions, mid‐term postoperative outcome is predictable to some extent.
Routine open abdomen treatment compared with on-demand open abdomen or direct closure following open repair of ruptured abdominal aortic aneurysms: A propensity score–matched study
Authors: Smidfelt Kristian , Nordanstig Joakim , Wingren Urban , Bergström Göran , Langenskiöld Marcus 
Published: February 2019

Objective: To investigate whether a strategy of treatment with a primarily open abdomen improves outcome in terms of mortality and major complications in patients treated with open repair for a ruptured abdominal aortic aneurysm compared to a strategy of primary closure of the abdomen. Design: Retrospective cohort study. Methods: Patients treated with a primarily open abdomen at a centre where this strategy was routine in most ruptured abdominal aortic aneurysm patients were compared to a propensity score–matched control group of patients who had the abdomen closed at the end of the primary operation in a majority of the cases. Results: In total, 79 patients treated with a primarily open abdomen after open repair for ruptured abdominal aortic aneurysm at Sahlgrenska University Hospital were compared to a propensity score–matched control group of 148 patients. The abdomen was closed at the end of the procedure in 108 (73%) of the control patients. There was no difference in 30-day mortality between patients treated with a primarily open abdomen at Sahlgrenska University Hospital and the controls, 21 (26.6%) versus 49 (33.1%), p = 0.37. The adjusted odds ratio for mortality at 30 days was 0.66 (95% confidence interval: 0.35–1.25) in patients treated with a primarily open abdomen at Sahlgrenska University Hospital compared to the controls. No difference was observed between the groups regarding 90-day mortality, postoperative renal failure requiring renal replacement therapy, postoperative intestinal ischaemia necessitating bowel resection or postoperative bleeding requiring reoperation. Conclusions: The study did not show any survival advantage or difference in major complications between patients treated with a primarily open abdomen after open repair for ruptured abdominal aortic aneurysm and propensity-matched controls where the abdomen was primarily closed in a majority of the cases.