Statistical modelling for effect of mix-parameters on properties of high-flowing sand-concrete

The high-flowing sand-concrete （HFSC） containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse sand ratio, dosage of additions, water to binder ratio and dosage of admixtures. Mini-cone slump test, v-fl.mnel time test and viscosity model parameters were used to characterize the behaviour of HFSC in fresh state. The mechanical compressive strength in 28 d was also determined. A factorial design approach was used to establish models highlighting the effect of each mix-parameter on measured properties of HFSC. The derived models are valid for mixtures made with 0 to 0.3 of dune sand to total sand ratio, 82 to 418 kg/m3 of marble powder, 0.42 to 0.46 of water/binder ratio and 1.3% to 1.9% of superplasticizer high water-reducer. The results show that the derived models constitute very efficient means for understanding the influence of key mix-parameters on HFSC properties and are useful in selecting the optimum mix proportions, by simulating their impact on fluidity, stability and compressive strength.

Influence of fly ash on early-age cracking behavior of high-flowing concrete

The effects of quality and content of fly ash on the early-age cracking behavior of high-flowing concrete （HFC） were investigated. The early-age cracking behavior of the HFC was analyzed by combining the tests of evaporation capacity and electrical resistivity of the HFC. In these tests, a modified flat-type specimen was adopted. The results show that the HFC will have a lower evaporation capacity when it is mixed with fine fly ash, while it will have a higher evaporation capacity when grade II! fly ash is used as mineral admixture. And the electrical resistivity rate of HFC reduces with the increase of the content of fly ash. A nonlinear relationship exists between the cracking time of HFC and the minimum electrical resistivity. The early-age cracking behavior of HFC with fly ash can be enhanced by appropriately increasing the fine particle content and MgO, K2O, and SO3 contents of fly ash. The optimal content of fly ash, which makes a satisfied early-age cracking behavior of HFC, is obtained. And when the content of fly ash exceeds a critical value, the early-age cracking behavior of HFC will rapidly decrease.

Analysis of the Efficacy of Humidified High-Flow Nasal Oxygen Therapy Combined with Alveolar Lavage in the Treatment of Patients with Severe Pneumonia Complicated with Respiratory Failure

Objective:To analyze the curative effect of humidified high-flow nasal oxygen therapy combined with alveolar lavage in patients with severe pneumonia and respiratory failure.Methods:120 patients with severe pneumonia complicated with respiratory failure admitted to the Third People’s Hospital of Xining from July 2021 to December 2022 were randomly divided into two groups:group A and group B.The patients in group A were given humidified high-flow nasal oxygen therapy combined with alveolar lavage,whereas those in group B were given humidified high-flow nasal oxygen therapy.The treatment efficacy,blood gas analysis results,and differences in inflammatory mediators were compared between the two groups.Results:The curative effect in group A(96.67%)was significantly higher than that in group B(81.67%),P<0.05;the partial pressure of carbon dioxide(PaCO2),partial pressure of oxygen(PaO2),oxygen saturation(SpO2),and Horowitz index(P/F)of group A were significantly better than group B,P<0.05;the interleukin 6(IL-6),tumor necrosis factor alpha(TNF-α),and C-reactive protein(CRP)levels,white blood cell(WBC)count,serum procalcitonin(PCT),and neutrophil(N)percentage of group A were significantly lower than those of group B,P<0.05.Conclusion:For patients with severe pneumonia complicated with respiratory failure,alveolar lavage,on the basis of humidified high-flow oxygen therapy,can inhibit local inflammation,improve blood gas analysis results,promote disease recovery,and improve the clinical treatment effect。

High-flow nasal cannula oxygen therapy and noninvasive ventilation for preventing extubation failure during weaning from mechanical ventilation assessed by lung ultrasound score: A single-center randomized study

BACKGROUND: We sought to demonstrate the superiority of a targeted therapy strategy involving high-flow nasal cannula oxygen(HFNCO_(2)) therapy and noninvasive ventilation(NIV) using lung ultrasound score(LUS) in comparison with standard care among patients in the intensive care unit(ICU) who undergo successful weaning to decrease the incidence of extubation failure at both 48 hours and seven days.METHODS: During the study period, 98 patients were enrolled in the study, including 49 in the control group and 49 in the treatment group. Patients in the control group and patients with an LUS score <14 points(at low risk of extubation failure) in the treatment group were extubated and received standard preventive care without NIV or HFNCO_(2). Patients with an LUS score ≥14 points(at high risk of extubation failure) in the treatment group were extubated with a second review of the therapeutic optimization to identify and address any persisting risk factors for postextubation respiratory distress;patients received HFNCO2 therapy combined with sessions of preventive NIV(4-8 hours per day for 4-8 sessions total) for the first 48 hours after extubation.RESULTS: In the control group, 13 patients had the LUS scores ≥14 points, while 36 patients had scores <14 points. In the treatment group, 16 patients had the LUS scores ≥14 points, while 33 patients had scores <14 points. Among patients with the LUS score ≥14 points, the extubation failure rate within 48 hours was 30.8% in the control group and 12.5% in the treatment group, constituting a statistically significant difference(P<0.05). Conversely, among patients with an LUS score <14 points, 13.9% in the control group and 9.1% in the treatment group experienced extubation failure(P=0.61). The length of ICU stay(9.4±3.1 days vs. 7.2±2.4 days) was significantly different and the re-intubation rate(at 48 hours: 18.4% vs. 10.2%;seven days: 22.4% vs. 12.2%) significantly varied between the two groups(P<0.05). There was no significant difference in the 28-day mortality rate(6.1% vs. 8.2%) between the control and treatment groups.CONCLUSIONS: Among high-risk adults being weaned from mechanical ventilation and assessed by LUS, the NIV+HFNCO_(2) protocol does not lessen the mortality rate but reduce the length of ICU stay, the rate of extubation failure at both 48 hours and seven days.

Design and Experiment-Based Optimization of High-Flow Hydraulic One-Way Valves

High-flow hydraulic one-way valves in water pipes are typically used to mitigate conditions,which would otherwise cause vibration and cavitation erosion after long-term operation.To prevent cavitation and enhance the performance of hydraulic one-way valves,in the present work a dedicated experimental study has been conducted.The structural parameters relating to the pilot valve core,the main valve core,and the through-flow section of the considered flow channel have been changed to analyse reverse impact,and cavitation,characteristics.The results show that the control pressure has a weak effect on the cavitation characteristics,while changes in the structural parameters can significantly affect them.In particular,the cavitation index,representing the extent of cavitation,has been found to display a linear correlation with the inlet pressure,but,not with the inlet flow rate.Most importantly,a stepped throttling structure can reduce the pressure oscillation,improve the response speed,enhance the impact characteristics,and decrease the likelihood and severity of cavitation.The larger the flow passage area,the shorter the unloading time.Cavitation mainly occurs when the pilot valve core is fully opened.The stepped main valve core throttling structure has been found to be an optimal option.

Dynamic characteristics of the high-flow water three-way valve

Operating principle of water three-way valve with high flow for individual hydraulic prop in coal was presented in this paper, its strict and precise mathematical model was established, its flow field was simulated numerically by software Fluent, and its dynamic characteristics were analyzed during the work process such as raising leg, loading and overflow, the influence of the related parameters on high-flow water three-way valve was determined. The results as follows： during the raising leg stage and early raising leg stage, when the damping ratio increases, the overshoot of system decreases and the setting time reduces, and the dynamic response performance has a significant improvement. During the loading stage and the overflow stage, the pressure in plunger chamber of single hydraulic prop, the output flow and the displacement of the high-flow water three-way valve decrease with the decreasing of the external load. The spring stiffness of the safety valve directs the flow and the spool＇s displacement of the safety valve, and it can be used to control the high-flow three-way valve＇s sensitivity.

Sleep Quality for Patients Receiving Noninvasive Positive Pressure Ventilation and Nasal High-Flow Oxygen Therapy in an ICU: Two Case Studies

Aim: The purpose of this case study was to examine the sleep quality of patients receiving noninvasive positive pressure ventilation (NPPV) or nasal high-flow oxygen therapy (NHF) in an intensive care unit and to investigate what types of nursing support are offered to such patients. Methods: We examined one patient each for NPPV and NHF. Polysomnography (PSG), review of the patient charts, and semi-structured interviews were used to collect the data for analysis. Results: Patients treated with NPPV or NHF demonstrated a noticeable reduction in deep sleep, with most of their sleep being shallow. Their sleep patterns varied greatly from those of healthy individuals. These results suggest that, in addition to experiencing extremely fragmented sleep, sleep in these patients was more likely to be interrupted by nursing interventions, such as during auscultation of breath sounds. Furthermore, it was revealed that “anxiety or discomfort that accompanies the mask or air pressure” in patients treated with NPPV and “discomfort that accompanies the nasal cannula or NHF circuit” in patients treated with NHF may be primary causes of disrupted sleep. Our results suggest a need for nursing care aimed at improving sleep quality in patients treated with NPPV or NHF.

Efficacy of high-flow nasal cannula on acute exacerbation of chronic obstructive pulmonary disease: A meta-analysis

Objective:To systematically evaluate the efficacy and feasibility of high-flow nasal cannula(HFNC)on patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).Methods:Systematic searches on PubMed,Web of Science,the Cochrane Library,Embase,CBM(Chinese Biomedicine Database),CNKI(China National Knowledge Infrastructure),Wanfang Database and VIP were performed for randomized controlled trials(RCTs)which explored the effects of HFNC on patients with AECOPD.The retrieval time was from the establishment of each database to July 2019.RevMan5.3 software was used for statistical analysis.Results:A total of 12 articles were included,involving 812 patients.The results showed that:(1)Compared with conventional oxygen therapy,HFNC could improve patients'arterial partial oxygen pressure(PaO2)(MD=12.70,95%CI(7.00,18.40),Z=4.37,P<0.0001),reduce partial arterial blood carbon dioxide(PaCO2)(MD=-10.99,95%CI(-14.42,-7.55),Z=6.26,P<0.00001)and reduce endotracheal intubation rate(OR=0.19,95%CI(0.04,0.93),Z=2.05,P=0.04),shorten the hospitalization time(SMD=-0.74,95%CI(-1.11,-0.37),Z=3.95,P<0.0001).(2)Compared with non-invasive positive pressure ventilation,it has fewer adverse reactions(OR=0.18,95%CI(0.09,0.35),Z=5.08,P<0.00001)and shorter hospital stay(SMD=-0.57,95%CI(-0.90,-0.23),Z=3.33,P=0.0009).Conclusion:HFNC can improve the patients’hypoxia symptoms and CO2 retention,reduce the rate of tracheal intubation,and alleviate adverse reactions.However,Limited by the quality and region of the included studies,more high-quality are needed to test it.

Prone position combined with high-flow nasal oxygen could benefit spontaneously breathing, severe COVID-19 patients:A case report

BACKGROUND Since the outbreak of coronavirus disease 2019(COVID-19)in Wuhan,China in December 2019,the overall fatality rate of severe and critical patients with COVID-19 is high and the effective therapy is limited.CASE SUMMARY In this case report,we describe a case of the successful combination of the prone position(PP)and high-flow nasal oxygen(HFNO)therapy in a spontaneously breathing,severe COVID-19 patient who presented with fever,fatigue and hypoxemia and was diagnosed by positive throat swab COVID-19 RNA testing.The therapy significantly improved the patient's clinical symptoms,oxygenation status,and radiological characteristics of lung injury during hospitalization,and the patient showed good tolerance and avoided intubation.Additionally,we did not find that medical staff wearing optimal airborne personal protective equipment(PPE)were infected by the new coronavirus in our institution.CONCLUSION We conclude that the combination of PP and HFNO could benefit spontaneously breathing,severe COVID-19 patients.The therapy does not increase risk of healthcare workers wearing optimal airborne PPE to become infected with virus particles.

Efficacy and Safety of Treatment of High-flow Priapism with Superselective Transcatheter Embolization

This study is aimed to evaluate the effectiveness and safety of the treatment of highflow priapism with superselective transcatheter embolization.From Sep.1999 to Jan.2013,six patients with high-flow priapism underwent superselective transcatheter embolization of the cavernous artery.Recurrence of priapism,and change in erectile function detected by nocturnal penile tumescence and rigidity(NPTR)test and the International Index of Erectile Function 5-item questionnaire(IIEF-5)were evaluated during a mean follow-up of 12 months.A single superselective transcatheter embolization was sufficient for complete resolution of priapism in the six patients.None of the patients had a relapse of priapism after embolization,and all the patients who had premorbid normal erectile function showed maintained potency with normal results of NPTR and a mean postoperative IIEF-5 score of 23.5(range 23 to 24)during the follow-up period.In conclusion,superselective transcatheter embolization is an effective and safe treatment method for high-flow priapism,and it can ensure a high level of preservation of premorbid erectile function.

The effect of high-flow oxygen via tracheostomy on respiratory pattern and diaphragmatic function in patients with prolonged mechanical ventilation:A randomized,physiological,crossover study

Background Compared to conventional oxygen devices,high-flow oxygen treatment(HFOT)through the nasal cannulae has demonstrated clinical benefits.Limited data exist on whether such effects are also present in HFOT through tracheostomy.Hence,we aimed to examine the short-term effects of HFOT through tracheostomy on diaphragmatic function and respiratory parameters in tracheostomized patients on prolonged mechanical ventilation.Methods A randomized,crossover,physiological study was conducted in our ICU between December 2020 and April 2021,in patients with tracheostomy and prolonged mechanical ventilation.The patients underwent a 30-min spontaneous breathing trial(SBT)and received oxygen either via T-piece or by HFOT through tracheostomy,followed by a washout period of 15-min breathing through the T-piece and receipt of 30-min oxygen with the other modality in a randomized crossover manner.At the start and end of each session,blood gasses,breathing frequency(f),and tidal volume(VT)via a Wright's spirometer were measured,along with diaphragm ultrasonography including diaphragm excursion and diaphragmatic thickening fraction,which expressed the inspiratory muscle effort.Results Eleven patients were enrolled in whom 19 sessions were uneventfully completed;eight patients were studied twice on two different days with alternate sessions;and three patients were studied once.Patients were randomly assigned to start the SBT with a T-piece(n=10 sessions)or with HFOT(n=9 sessions).With HFOT,VT and minute ventilation(VE)significantly increased during SBT(from[465±119]mL to[549±134]mL,P<0.001 and from[12.4±4.3]L/min to[13.1±4.2]L/min,P<0.05,respectively),but they did not change significantly during SBT with T-piece(from[495±132]mL to[461±123]mL and from[12.8±4.4]mL to[12.0±4.4]mL,respectively);f/VT decreased during HFOT(from[64±31]breaths/(min∙L)to[49±24]breaths/(min∙L),P<0.001),but it did not change significantly during SBT with T-piece(from[59±28]breaths/(min∙L)to[64±33]breaths/(min∙L));partial pressure of arterial oxygen increased during HFOT(from[99±39]mmHg to[132±48]mmHg,P<0.001),but it decreased during SBT with T-piece(from[124±50]mmHg to[83±22]mmHg,P<0.01).In addition,with HFOT,diaphragmatic excursion increased(from[12.9±3.3]mm to[15.7±4.4]mm,P<0.001),but it did not change significantly during SBT with T-piece(from[13.4±3.3]mm to[13.6±3.3]mm).The diaphragmatic thickening fraction did not change during SBT either with T-piece or with HFOT.Conclusion In patients with prolonged mechanical ventilation,HFOT through tracheostomy compared with T-piece improves ventilation,pattern of breathing,and oxygenation without increasing the inspiratory muscle effort.Trial Registration Clinicaltrials.gov ldentifer:NCT04758910.

The relationship between ENSO cycle and high and low-flow in the upper Yellow River

Firstly, the hydrological and meteorological features of the upper reaches of the Yellow River above Tangnag are analyzed based on observation data, and effects of EI Nino and La Ni na events on the high and low flow in the upper Yellow River are discussed. The results show El Nino and La Nina events possess consanguineous relationship wi th runoff in the upper Yellow River. As a whole, the probability of low fl ow occurrence in the upper Yellow River is relatively great along wit h the occurrence of El Nino event. Moreover, the flood in the upper Yellow River occurs frequently with the occurrence of La Nina event. Besides, the results also show dissimilarity of El Nino event occurri ng time exerts greater impact on high flow and low flow in the uppe r Yellow River, that is, the probability of drought will be greater in the sam e year if El Nino event occurs in spring, the high-flow may happen in this y ear if El Nino occurs in summer or autumn; the longer the continuous period of El Nino is, the lower the runoff in the upper Yellow River is.

High-flow nasal cannula oxygen therapy in acute hypoxemic respiratory failure and COVID-19-related respiratory failure

Although standard oxygen face masks are first-line therapy for patients with acute hypoxemic respiratory failure,high-flow nasal cannula oxygen therapy has gained major popularity in intensive care units.The physiological effects of high-flow oxygen counterbalance the physiological consequences of acute hypoxemic respiratory failure by lessening the deleterious effects of intense and prolonged inspiratory efforts generated by patients.Its simplicity of application for physicians and nurses and its comfort for patients are other arguments for its use in this setting.Although clinical studies have reported a decreased risk of intubation with high-flow oxygen compared with standard oxygen,its survival benefit is uncertain.A more precise definition of acute hypoxemic respiratory failure,including a classification of severity based on oxygenation levels,is needed to better compare the efficiencies of different non-invasive oxygenation support methods(standard oxygen,high-flow oxygen,and non-invasive ventilation).Additionally,the respective role of each non-invasive oxygenation support method needs to be established through further clinical trials in acute hypoxemic respiratory failure,especially in severe forms.

Oxygenation strategies after extubation of critically ill and postoperative patients

In intensive care units(ICUs),the decision to extubate is a critical one because mortality is particularly high in case of reintubation.Around 15%of patients ready to be weaned offa ventilator experience extubation failure leading to reintubation.The use of high-flow nasal oxygen and non-invasive ventilation are two alternatives of standard oxygen supplementation that may help to prevent reintubation.High-flow nasal oxygen and non-invasive ventilation,may be used to prevent reintubation in patients with low(e.g.,patients without comorbidities and with short durations of mechanical ventilation)and high risk(e.g.,patients>65 years and those with underlying cardiac disease,chronic respiratory disorders,and/or hypercapnia at the time of extubation)of reintubation,respectively.However,non-invasive ventilation used as a rescue therapy to treat established post-extubation respiratory failure could increase mortality by delaying reintubation,and should therefore be used very carefully in this setting.The oxygenation strategy to be applied in postoperative patients is different from the patients who are extubated in the ICUs.Standard oxygen after a surgical procedure is adequate,even following major abdominal or cardio-thoracic surgery,but should probably be switched to high-flow nasal oxygen in patients with hypoxemic.Unlike in patients experiencing post-extubation respiratory failure in ICUs wherein non-invasive ventilation may have deleterious effects,it may actually improve the outcomes in postoperative patients with respiratory failure.This review discusses the different clinical situations with the aim of choosing the most effective oxygenation strategy to prevent post-extubation respiratory failure and to avoid reintubation.