Respiratory Mechanics, Respiratory Muscle Strength, Control of Ventilation and Gas Exchange in Patients with Autoimmune Liver Disease

Objectives: To assess respiratory elastance and resistive properties in patients with autoimmune liver disorders using the passive relaxation expiration technique and compare findings to a group of patients with non-autoimmune liver disease and control subjects. These findings were then related to control of ventilation and gas exchange. A secondary objective was to assess respiratory muscle strength and gas exchange and their relation to respiratory mechanics. Methods: Measurements included respiratory elastance and resistance using the passive relaxation method. Pulmonary function, gas exchange and control of ventilation were assessed using standard methods. Results: a) Compared to control subjects, Ers in patients with liver disease was on average 50% greater than in controls;b) mean respiratory resistance, expressed as the respiratory constants, K1 and K2 in the Rohrer relationship, Pao/V’ = K1 + K2V’, was not different from control resistance;c) mean maximal inspiratory and maximal expiratory pressures averaged 36% and 55% of their respective control values;d) inspiratory occlusion pressure in 0.1 sec (P0.1) was increased and negatively associated with FVC;and e) increases in P0.1, mean inspiratory flow (Vt/Ti) and presence of respiratory alkalosis confirmed the increase in ventilatory drive. Despite inspiratory muscle weakness in patients, P0.1/Pimax averaged 5-fold higher than in control subjects. Conclusions: Despite inspiratory muscle weakness and a V’E similar to that in normal subjects, central drive is increased in patients with chronic liver disease. The increase in ventilatory drive is related to smaller lung volumes and weakly associated with increase in respiratory elastance. Findings confirm that P0.1 is a reliable measure of central drive and is an approach that can be used in the evaluation of control of ventilation in patients with chronic liver disease.

The effect of different inflation volumes of laryngeal mask airway on efficacy of closed circuit controlled ventilation in pediatric cancer patients

Objective： The laryngeal mask airway （LMA） is an established way for airway control during spontaneous ventila- tion. Its ability to deliver positive pressure ventilation without leakage especially in low flow states is still controversy. The aim of this study is to test the possibility of using LMA in pediatric closed circuit controlled ventilation, and to find out the optimum cuff volume to perform closed system ventilation. Methods： Twenty children scheduled for elective surgeries were enrolled in a crossover study. Laryngeal mask airway was used. In stage I, the cuff was inflated with the maximum volume of air as rec- ommended by the manufacturers. Adjustment of volume of air inflated into the LMA cuff to the minimum volume to obtain the effective seal was done at stage II. The leak pressure, intracuff pressure and the leak volume were measured in both stages. Results： The cuff filling volume was significantly lower compared to the maximum cuff inflation volume in stage I. Leakage values showed significantly less values in stage II of the study with smaller cuff inflation volumes. The airway leakage pressure was significantly lower in stage fl in comparison to stage I. Cuff inflation pressure in stage I showed marked elevation which dropped significantly after adjustment of cuff volume in stage I1. Conclusion： Laryngeal mask airway is an effective tool to provide closed circuit controlled ventilation in pediatrics. Inflation of the cuff by the minimum volume of air needed to reach the just sealing pressure is suggested to minimize the leakage volume.

Optimized model-based control of main mine ventilation air flows with minimized energy consumption

In early 2018,the Boliden Garpenberg operation implemented an optimized control strategy as an addition to the existing ventilation on demand system.The purpose of the strategy is to further minimize energy use for main and booster fans,whilst also fulfilling airflow setpoints without violating constraints such as min/max differential pressure over fans and interaction of air between areas in mines.Using air flow measurements and a dynamical model of the ventilation system,a mine-wide coordination control of fans can be carried out.The numerical model is data driven and derived from historical operational data or step changes experiments.This makes both initial deployment and lifetime model maintenance,as the mine evolves,a comparably easy operation.The control has been proven to operate in a stable manner over long periods without having to re-calibrate the model.Results prove a 40%decrease in energy use for the fans involved and a greater controllability of air flow.Moreover,a 15%decrease of the total air flow into the mine will give additional proportional heating savings during winter periods.All in all,the multivariable controller shows a correlation between production in the mine and the ventilation system performance superior to all of its predecessors.

Dimensionless Study on Secretion Clearance of a Pressure Controlled Mechanical Ventilation System with Double Lungs

A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently.Studies on secretion clearance by pressure controlled systems show that these are suited for clinical applications.However,these studies are based on a single lung electric model and neglect the coupling between the two lungs.The research methods applied are too complex for the analysis of a multi-parameter system.In order to understand the functioning of the human respiratory system,this paper develops a dimensionless mathematical model of doublelung mechanical ventilation system with a secretion clearance function.An experiment is designed to verify the mathematical model through comparison of dimensionless experimental data and dimensionless simulation data.Finally,the coupling between the two lungs is studied,and an orthogonal experiment designed to identify the impact of each parameter on the system.

Modelling and Simulation of Pressure Controlled Mechanical Ventilation System

A mathematical model of mechanical ventilator describes its behavior during artificial ventilation. This paper purposes to create and simulate Mathematical Model (MM) of Pressure Controlled Ventilator (PCV) signal. This MM represents the respiratory activities and an important controlled parameter during mechanical ventilation—Positive End Expiration Pressure (PEEP). The MM is expressed and modelled using periodic functions with inequalities to control the beginning of inspiration and expiration durations. The created MM of PCV signal is combined with an existing multi compartmental model of respiratory system that is modified and developed in the internal parameters—compliances (C) to test created MM. The created MM and model of respiratory system are constructed and simulated using Simulink package in MATLAB platform. The obtained simulator of mechnical ventilation system could potentially represent the pressure signal of PVC as a complete respiratory cycle and continuance waveform. This simulator is also able to reflect a respiratory mechanic by changing some input variables such as inspiration pressure (IP), PEEP and C, which are monitored in volume, flow, pressure and PV loop waveforms. The obtained simulator has provided a simple environment for testing and monitoring PCV signal and other parameters (volume, flow and dynamic compliance) during artificial ventilation. Furthermore, the simulator may be used for studying in the laboratory and training ventilator’s operators.

Harmonic excitation of linear respiratory mechanics for physiological dual controlled ventilation

The theoretical approach along with the rationale of harmonic excitation modality (HEM) applied as optimal dual controlled ventilation (DCV) to anaesthetized or severe brain injured patients, whose respiretory mechanics can be properly assumed steady and linear, are presented and discussed. The design criteria of an improved version of the Advanced Lung Ventilation System (ALVS), including HEM in its functional features, are described in details. In particular, the elimination of any undesiderable artificial distortion affecting the respiratory and ventilation pattern waveforms is achieved by maintaining continuous forever the airflow inside the ventilation circuit, ensuring also the highest level of safety for patient in any condition. In such a way, the full-time compatibility of controlled breathings with spontaneous breathing activity of patient during continuous positive airways pressure (CPAP) or bilevel positive airways pressure (BiPAP) ventilation modalities and during assisted/controlled ventilation(A/CV), includeing also synchronized or triggered ventilation modalities, is an intrinsic innovative feature of the system available for clinical application. As expected and according to the clinical requirements, HEM provides for physiological respiratory and ventilation pattern waveforms together with optimal “breath to breath” feedback control of lung volume driven by an improved diagnostic measurement procedure, whose outputs are also vital for adapting all the preset ventilation parameters to the current value of the respiratory parameters of patient. The results produced by software simulations concerning both adult and neonatal patients in different clinical conditions are completely consistent with those obtained by the theoretical treatment, showing that HEM reaches the best performances from both clinical and engineering points of view.

Theoretical modeling of airways pressure waveform for dual-controlled ventilation with physiological pattern and linear respiratory mechanics

The present paper describes the theoretical treatment performed for the geometrical optimization of advanced and improved-shape waveforms as airways pressure excitation for controlled breathings in dual-controlled ventilation applied to anaesthetized or severe brain injured patients, the respiratory mechanics of which can be assumed linear. Advanced means insensitive to patient breathing activity as well as to ventilator settings while improved-shape intends in comparison to conventional square waveform for a progressive approaching towards physiological transpulmonary pressure and respiratory airflow waveforms. Such functional features along with the best ventilation control for the specific therapeutic requirements of each patient can be achieved through the implementation of both diagnostic and compensation procedures effectively carried out by the Advance Lung Ventilation System (ALVS) already successfully tested for square waveform as airways pressure excitation. Triangular and trapezoidal waveforms have been considered as airways pressure excitation. The results shows that the latter fits completely the requirements for a physiological pattern of endoalveolar pressure and respiratory airflow waveforms, while the former exhibits a lower physiological behaviour but it is anyhow periodically recommended for performing adequately the powerful diagnostic procedure.

Experimental Investigation of Demand Controlled Ventilation Systems： A Suitable Alternative for Controlling Ventilation in Dwellings

Indoor CO2 concentration depends on the number of persons, their metabolic rates, other sources of indoor pollution, ventilation rate and ventilation efficiency. These factors are not considered by the Spanish technical building code since ventilation is set only by a fixed air change rate. This paper aims to explore the possibilities of DCVS （demand controlled ventilation systems） to ensure adequate and sustainable ventilation. It is based on a research project carried out by the University of the Basque Country （EHU-UPV） and Euskadi Public Housing and Soil Join-Stock Company （VISESA）： the living rooms of 90 dwellings were provided with DCVS, where CO2 sensors were used to dynamically control the ventilation rate. Tests were carried out using tracer gas techniques, with results showing the air age to be adequate at every point of the occupied zones and free of stagnant areas, therefore proving the system＇s effectiveness and rapid response, and its energy savings.

PCV-VG和VCV模式对腹腔镜手术患者肺顺应性的影响

目的:探析压力控制容量保证(PCV-VG)模式与容量控制(VCV)模式对腹腔镜手术患者的应用价值。方法:将90例腹腔镜手术患者以掷硬币法分为A组(n=45)和B组(n=45),A组行VCV,B组行PCV-VG,比较2组血流动力学、动态肺顺应性、临床指标和并发症发生情况。结果:2组MAP在T2、T3、T4时点时均低于T1、T5时点(P<0.05);2组T3动态肺顺应性低于T2、T4,B组各时点均高于A组(P<0.05);2组各时间点的心率、拔管时间及并发症发生率比较差异均无统计学意义;B组术后住院时间短于A组(P<0.05)。结论:PCV-VG和VCV对腹腔镜手术患者血流动力学的影响一致,PCV-VG更有助于改善肺顺应性,促进术后恢复。

Effect of Prone Position Ventilation in Patients with Severe Craniocerebral Injury Complicated with Pulmonary Infection

Objective:To investigate the effects of prone ventilation in patients with severe traumatic brain injury combined with pulmonary infection.Methods:A total of 100 patients with severe traumatic brain injury combined with pulmonary infection in the hospital were randomly divided into a prone ventilation group and a conventional ventilation group,with 50 patients in each group.The Glasgow Coma Scale(GCS)score,APACHE II score,sputum culture results,oxygenation indicators,and prognosis were compared between the two groups.Data were processed using SPSS 25.0 statistical software,and t-tests and chi-square tests were used to compare continuous and categorical variables,respectively.Results:The experimental group showed better oxygenation indicators,a lower positive rate of sputum cultures,and reduced intracranial pressure compared to the control group(all P<0.05).Multivariate Cox regression analysis indicated that GCS score,APACHE II score,and prone ventilation were independent risk factors affecting patient prognosis(all P<0.05).Conclusion:Prone ventilation can improve oxygenation,reduce the risk of pulmonary infection,and decrease intracranial pressure in patients with severe traumatic brain injury combined with pulmonary infection,thereby improving patient prognosis.GCS score and APACHE II score can serve as important indicators for prognostic evaluation.

VCV与PCV通气策略中不同参数调节下雾化治疗对VTi、VTe及Ppeak指标的影响

目的:探究容量控制通气策略(VCV)和压力控制通气策略(PCV)时不同参数调节的雾化吸入对呼吸力学指标的影响。方法:以随机抽样法为分组依据,将本院抽取的100例机械通气患者分为VCV组(容量控制通气模式)与PCV组(压力控制通气模式)各50例,均于2020年1月—2021年1月期间在本院接受雾化吸入治疗,再将两组根据雾化氧流量参数不同进行分组,其中PCV组雾化氧流量7L/min有23例,9L/min有27例;VCV组雾化氧流量7L/min有26例,9L/min有24例;观察在2种模式下(雾化氧流量分别定为7、9L/min时)在雾化开始之前(雾化氧流量为0)和开始之后10min患者呼吸力学指标[气道峰压(Ppeak)、吸入潮气量(VTi)、呼出潮气量(VTe)]。同时,进行模拟水肺体外实验,观察在不同模式与呼吸机参数条件下雾化10min后(氧流量分别为0、5、7、9L/min)呼吸力学指标的变化。结果:临床研究显示,VCV模式中,患者的VTe、Ppeak随外接雾化氧流量的增加而升高(P<0.05),VTi则没有明显的改变(P>0.05)。PCV模式中,随外接雾化氧流量的增加,患者的VTi降低、VTe升高(P<0.05),Ppeak没有明显改变(P>0.05)。模拟水肺体外实验显示,VCV模式下,不同预设VT各组模拟水肺显示的VT和呼吸机监测的VTe会随着雾化氧流量增加而升高,不同雾化氧流量间差异显著(均P<0.05);而呼吸机监测的VTi无显著变化(P>0.05)。雾化10min后,不同预设VT各组呼吸机监测的VTe在相同雾化氧流量下均明显高于模拟水肺显示的VT,而VTi均显著低于模拟水肺显示的VT(均P<0.05)。PCV模式下,不同预设吸气压力各组呼吸机监测的Ppeak无明显变化(P>0.05);而VTe随着雾化氧流量增加而逐渐升高,VTi逐渐降低,不同雾化氧流量间差异显著(均P<0.05);雾化开始后10min,在相同雾化氧流量下,VTe均明显高于模拟水肺显示的VT,VTi在明显低于模拟水肺显示的VT(均P<0.05)。结论:VCV通气策略下,雾化氧流量的增加会导致患者端的VT升高;PCV通气策略下,患者端的VT、Ppeak无明显变化。在上述两种通气策略下,呼吸机监测的VTi和VTe均无法真实反映患者端的VT。

PCV-VG和VCV模式用于老年患者腹腔镜腹部手术的术中氧合功能及创伤程度评估

目的:研究了PCV-VG和VCV模式用于老年患者腹腔镜腹部手术的术中氧合功能及创伤程度。方法:选择60例接受腹腔镜腹部手术的老年患者进行研究,随机分为两组,A组按照VCV序贯PCV-VG模式进行通气,B组按照PCV-VG序贯VCV模式进行通气,气腹开始前(T0)、气腹开始后第一种通气模式开始后1h(T_1)、切换通气模式通气后1h(T_2),气腹结束后(T_3)分别测定呼吸功能参数、动脉血气参数以及血清损伤指标。结果:T_1时间点处,A组患者的P_(peak)、P_(mean)、P_(plant)均显著高于B组,PaO_2显著低于B组,SpO_2、PaCO_2与B组无显著性差异;T_2和T_3时间点处,A组的P_(peak)、P_(mean)、Pp la n t均显著低于B组,PaO_2显著低于B组,SpO_2、PaCO_2与B组无显著性差异。T_1时间点处,A组的血清sRAGE、KL-6、TNF-α、MDA含量显著高于B组;T_3时间点处,A组的血清sRAGE、KL-6、TNF-α、MDA含量显著低于B组。结论:PCV-VG模式用于老年患者腹腔镜腹部手术能够降低气道压力、改善肺顺应性以及肺泡氧化、减轻肺损伤以及全身创伤。

基于肺部感染控制窗结合自主呼吸试验时机下行序贯机械通气治疗COPD急性加重期疗效及对肺功能、血气指标的影响研究

目的 探讨基于肺部感染控制窗(PIC-W)结合自主呼吸试验(SBT)时机下行序贯机械通气治疗慢性阻塞性肺病急性加重期(AECOPD)患者的临床研究,为临床应用提供指导。方法 对笔者所在医院重症监护室(ICU)收治的86例行有创-无创序贯机械通气治疗的COPD急性加重期患者进行回顾性分析,根据切换点的选择分为对照组43例,选择PIC确定有创-无创序贯机械通气治疗时机,实验组43例选择PIC-W+SBT确定有创-无创序贯机械通气治疗时机。比较两组治疗效果。结果 两组患者治疗后FEV1、FVC值、PaCO_(2)、SaO_(2)显均高于治疗前,且实验组高于对照组(P<0.05);实验组治疗后PaO_(2)值、再次插管率、死亡率及并发症发生率均低于对照组(P<0.05);实验组机械通气总时间、ICU住院时间均短于对照组(P<0.05)。结论 基于肺部感染控制窗结合自主呼吸试验时机下行序贯机械通气治疗慢性阻塞性肺病急性加重期患者耐受性好,降低再次插管率、病死率,且在改善肺功能、血气指标及降低并发症方面具有积极作用,可在临床上推广应用。

PCV和VCV两种通气方式对COPD伴Ⅱ型呼吸衰竭治疗的比较

目的比较COPD伴Ⅱ型呼吸衰竭病人分别进行压力控制通气（PCV）和容量控制通气（VCV）模式对患者的影响，并探讨其临床意义。方法64例COPD合并Ⅱ型呼衰病人随机分为PCV组和VCV组。分别测这两组的平台压（Pplat）、血气变化及中心静脉压（CVP）变化。结果通气24小时后PCV组气道平台压低于VCV组。两组通气24小时后中心静脉压明显升高，而VCV组上升更明显，两组治疗24小时后血气结果均得到改善。结论对于COPD合并Ⅱ型呼衰病人采用PCV通气模式能更好地防止气压伤。且对血流动力学影响小。主张对COPD伴Ⅱ型呼衰病人可尽量采用PCV通气模式。

基于通风网络解算的矿井智能通风监控系统设计

针对传统通风系统存在风量供需不平衡、通风能耗高及可控性差等问题,结合矿井通风理论和通风网络解算技术,提出一套矿井智能通风监控系统。该系统通过井下监控分站读取智能传感设备中的环境参数,并通过以太网通信协议将数据上传至地面远程监控中心,在用户界面中提供数据终端显示,实现矿井通风的实时监测、远程调控、故障预警和智能决策等功能。该系统采用Cross迭代法进行通风网络的风量解算,计算矿井各分支的可调风量,优化通风网络风量,输出最优风量调节方案。应用测试表明,该系统能够智能选取调风策略,满足不同分支的实际通风需求,提高了矿井通风系统的安全性和可靠性,为矿井通风的智能管理提供有效方案。

胡家河煤矿工作面通风及瓦斯治理设计

为实现稳定安全的开采目标,分析了胡家河煤矿401106工作面情况,设计了U型通风系统和瓦斯防治工作方案,采取采前预抽的策略,有效地消除瓦斯安全隐患;设计了安全监测监控系统布置方案,对井下的环境参数进行动态监测。所得研究结果,当风量为1700 m3/min时能够满足安全生产的要求。该工作面采用的瓦斯安全系统与通风系统均有良好的应用成效。

Application of fiberoptic bronchscopy in patients with acute exacerbations of chronic obstructive pulmonary disease during sequential weaning of invasive-noninvasive mechanical ventilation

BACKGROUND:Early withdrawal of invasive mechanical ventilation(IMV) followed by noninvasive MV(NIMV) is a new strategy for changing modes of treatment in patients with acute exacerbations of chronic obstructive pulmonary disease(AECOPD) with acute respiratory failure(ARF).Using pulmonary infection control window(PIC window) as the switch point for transferring from invasive to noninvasive MV,the time for early extubation can be more accurately judged,and therapy efficacy can be improved.This study aimed to prospectively investigate the clinical effectiveness of fiberoptic bronchscopy(FOB) in patients with AECOPD during sequential weaning of invasive-noninvasive MV.METHODS:Since July 2006 to January 2011,106 AECOPD patients with ARF were treated with comprehensive medication and IMV after hospitalization.Patients were randomly divided into two groups according to whether fiberoptic bronchoscope is used(group A,n=54) or not(group B,n=52) during sequential weaning from invasive to noninvasive MV.In group A,for sputum suction and bronchoalveolar lavage(BAL),a fiberoptic bronchoscope was put into the airway from the outside of an endotracheal tube,which was accompanied with uninterrupted use of a ventilator.After achieving PIC window,patients of both groups changed to NIMV mode,and weaned from ventilation.The following listed indices were used to compare between the groups after treatment:1) the occurrence time of PIC,the duration of MV,the length of ICU stay,the success rate of weaning from MV for the first time,the rate of reventilatJon and the occurrence rate of ventilator-associated pneumonia(VAP);2) the convenience and safety of FOB manipulation.The results were compared using Student's f test and the Chi-square test.RESULTS:The occurrence time of PIC was(5.01 ±1.49) d,(5.87±1.87) d in groups A and B,respectively(P<0.05);the duration of MV was(6.98±1.84) d,(8.69±2.41) d in groups A and B,respectively(P<0.01);the length of ICU stay was(9.25±1.84) d,(11.10±2.63) d in groups A and B,respectively(P<0.01);the success rate of weaning for the first time was 96.30%,76.92%in groups A and B,respectively(P<0.01);the rate of reventilation was 5.56%,19.23%in groups A and B,respectively(P<0.05);and the occurrence rate of VAP was 3.70%,23.07%in groups A and B,respectively(P<0.01).Moreover,it was easy and safe to manipulate FOB,and no side effect was observed.CONCLUSIONS:The application of FOB in patients with AECOPD during sequential weaning of invasive-noninvasive MV is effective in ICU.It can decrease the duration of MV and the length of ICU stay,increase the success rate from weaning MV for the first time,reduce the rate of reventilation and the occurrence rate of VAP.In addition,such a method is convenient and safe in patients of this kind.

Study on optimization control method based on artificial neural network

In the goal optimization and control optimization process the problems with common artificial neural network algorithm are unsure convergence, insufficient post-training network precision, and slow training speed, in which partial minimum value question tends to occur. This paper conducted an in-depth study on the causes of the limi-tations of the algorithm, presented a rapid artificial neural network algorithm, which is characterized by integrating multiple algorithms and by using their complementary advan-tages. The salient feature of the method is self-organization, which can effectively prevent the optimized results from tending to be partial minimum values. Overall optimization can be achieved with this method, goal function can be searched for in overall scope. With op-timization control of coal mine ventilator as a practical application, the paper proves that by integrating multiple artificial neural network algorithms, best control optimization and goal optimized can be achieved.

基于HACCP与目标导向多维护理在重症肺炎机械通气患者中的应用

目的观察基于危害分析及关键控制点(HACCP)与目标导向多维护理在重症肺炎机械通气患者中的应用效果。方法选择2020年1月至2023年1月就诊于新沂市人民医院的重症肺炎机械通气患者80例为研究对象,以随机数字表法将其划归为40例观察组、40例对照组。对照组遵循重症肺炎机械通气常规式护理法施行护理,观察组于此基础上加用基于HACCP与目标导向多维护理,对2组干预后肺部感染评分(CPIS)、营养风险筛查表(NRS)评分、急性生理与慢性健康评分(APACHEⅡ评分)、机械通气时间、住院时间等进行比较。结果护理后,观察组重症肺炎机械通气患者CPIS评分、NRS评分、APACHEⅡ评分[(5.43±0.55)、(3.23±0.58)、(23.85±1.21)/(2.90±0.50)分]低于对照组[(6.35±0.48)、(4.33±0.47)、(25.16±0.60)/(3.95±0.60)分],机械通气时间、住院时间[(8.25±0.74)、(23.70±1.32)d]短于对照组[(10.85±0.83)、(32.03±1.27)d],差异均有统计学意义(P<0.05)。结论基于HACCP与目标导向多维护理对重症肺炎机械通气患者施加干预,利于其肺部感染、营养健康状态的改善,实现快速康复目标。

A comparative study of dust control practices in Chinese and Australian longwall coal mines

Mine dust is one of the main hazards in underground longwall mines worldwide.In order to solve the mine dust problem,a significant number of studies have been carried out regarding longwall mine dust control,both in China and Australia.This paper presents a comparative study of dust control practices in Chinese and Australian longwall mines,with particular references to statutory limits,dust monitoring methods and dust management practices,followed by a brief discussion on the research status of longwall mine dust control in both countries.The study shows that water infusion,face ventilation controls,water sprays,and deep and wet cutting in longwall shearer operations are commonly practiced in almost all underground longwall mines and that both Chinese and Australian longwall mine dust control practices have their own advantages and disadvantages.It is concluded that there is a need for further development and innovative design of more effective dust mitigation products or systems despite the development of various dust control technologies.Based on the examinations and discussions,the authors have made some recommendations for further research and development in dust control in longwall mines.It is hoped that this comparative study will provide beneficial guidance for scholars and engineers who are engaging in longwall mine dust control research and practice.