Slippery hydrogel with desiccation-tolerant‘skin’for high-precision additive manufacturing

Hydrogels inevitably undergo dehydration,structural collapse,and shrinkage deformation due to the uninterrupted evaporation in the atmosphere,thereby losing their flexibility,slipperiness,and manufacturing precision.Here,we propose a novel bioinspired strategy to construct a spontaneously formed‘skin’on the slippery hydrogels by incorporating biological stress metabolites trehalose into the hydrogel network,which can generate robust hydrogen bonding interactions to restrain water evaporation.The contents of trehalose in hydrogel matrix can also regulate the desiccation-tolerance,mechanical properties,and lubricating performance of slippery hydrogels in a wide range.Combining vat photopolymerization three-dimensional printing and trehalose-modified slippery hydrogels enables to achieve the structural hydrogels with high resolution,shape fidelity,and sophisticated architectures,instead of structural collapse and shrinkage deformation caused by dehydration.And thus,this proposed functional hydrogel adapts to manufacture large-scale hydrogels with sophisticated architectures in a long-term process.As a proof-of-concept demonstration,a high-precision and sophisticated slippery hydrogel vascular phantom was easily fabricated to imitate guidewire intervention.Additionally,the proposed protocol is universally applicable to diverse types of hydrogel systems.This strategy opens up a versatile methodology to fabricate dry-resistant slippery hydrogel for functional structures and devices,expanding their high-precision processing and broad applications in the atmosphere.

Evaluation of formaldehyde emission from particleboard using the large chamber and desiccator method at various loading ratios

We studied formaldehyde emission from uncoated particleboard with 16-mm thickness using the large chamber and the desiccator method. A chamber of 28.4 m3 was installed to simulate a mobile home. The formaldehyde off-gassing properties of particleboard were evaluated using the chamber. The relationship between the concentration obtained by the chamber and the values by the desiccator test was discussed in this study under different conditions of conditioning day, air exchange, and loading ratio. These two methods were compared and discussed regarding the formaldehyde emission level. Three loading ratios, 0.429 m2/m3, 0.264 m2/m3, and 0.132 m2/m3, were chosen to represent different applications of particleboard products. There was strong correlation between emissions and air exchange rates at equal product-loading ratios in the large chamber, the related coefficient R 2 exceeded 0.90. There was also an indication of a generic correlation between the large chamber and the two-hour desiccator test with a single product designated loading ratio, air exchange rate, and climatic conditions.

Effect of high light and desiccation on photosystem Ⅱ in the seedlings and mature plants of tropical seagrass Enhalus acoroides during low tide

During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The response of leaves of E.acoroides to high light and desiccation was compared for seedlings and mature plants.Results show that the resistance of seedling and mature leaves to high light was quite similar,but to desiccation was very different.Seedling leaves were more sensitive to desiccation than the mature plant leaves,but had better water retention.The damage of desiccation to seedling leaves was mainly caused by dehydration,whereas that to mature plant leaves was caused by hypersaline toxicity.The recovery rate of PSⅡ of seedling leaves was significantly slower than that of the mature plants after the stresses disappeared,which may at least partly contribute to seedling mortality in the wild.In addition,compared to high light,desiccation seriously inhibited the recovery rate of PSⅡ activities even if the leaves became fully rehydrated to their normal relative water content(RWC)in the following re-immersion.Desiccation inhibited the recovery rate of RC/CS_(M)(reaction center per cross section(at t=t_(Fm)))to decrease the production of assimilatory power,which maybe the cause of the slower PSⅡ recovery in desiccation treatments.This study demonstrates that desiccation particularly coupling with high light have a very negative ef fect on the PSⅡ of E.acoroides during low tide and the sensitivity of seedlings and mature plants to desiccation is significantly different,which have important reference significance to choose an appropriate transplanting depth where seedlings and mature plants of E.acoroides not only receive sufficient light for growth,but also that minimize desiccation stress during low tide.

高分子除湿转轮建模与除湿性能预测

为有效预测高分子除湿转轮的除湿性能,采用效率法模型、BP神经网络模型2种方式对基于高分子除湿转轮实验台的47组实验数据进行建模。通过构建的除湿转轮模型,对20组不同实验工况条件下的转轮除湿性能进行预测,并与实验数据进行对比。根据预测结果得出,2种模型均能对用于建模的47组实验数据进行有效回归,且能对非建模实验数据以外的20组实验工况进行较好的预测。效率法模型对于处理空气出口温度的预测精度优于BP神经网络模型,但对于处理空气出口含湿量的预测,BP神经网络模型的预测精度优于效率法模型。选择广州、上海、武汉、北京4个典型气候条件城市,使用所建模型研究其在不同气候分区下供冷季的除湿性能,结果表明高分子除湿转轮在这4个城市中的除湿性能由高到低依次为广州、上海、武汉、北京。

假泥裂:上扬子地区下三叠统飞仙关组灰岩薄层中的网纹沉积构造

【目的】上扬子地区西北缘下三叠统飞仙关组二段薄层灰岩中发育类似泥裂的沉积构造,由于前人对其成因和沉积环境存在误解,因此订正该沉积构造的特征及其环境意义很有必要。【方法和结果】通过野外调查及显微薄片观察发现该套灰岩单层厚度一般介于2~10 cm,呈薄板状或者渠槽状,显微薄片显示其为微晶颗粒灰岩,含大量腹足类、介形类、双壳类化石和粪球粒。槽模及渠模构造显示灰岩为频繁的风暴所致,薄板状灰岩中发育的假泥裂沉积构造在岩层顶底面呈不规则四边形或五边形,实为压溶作用形成的方解石脉分割所致,成岩期压实作用及构造作用是假泥裂构造形成的动力学诱因。【结论】飞仙关组中网纹构造的普遍存在预示着灰岩沉积于较深水环境,假泥裂的识别对奥陶系宝塔组网纹灰岩的成因具有借鉴意义。

西辽河生态复苏进展与对策

西辽河是我国七大江河中唯一处于断流状态的大江大河干流,2024年全国水利工作会议提出“力争实现西辽河干流全线过流”目标。分析了西辽河流域水资源条件及开发利用状况,根据水资源调查评价结果,流域水资源短缺且衰减剧烈,地下水水位持续下降,西辽河生态环境复苏面临河道断流、地下水超采、河道侵占、主河槽萎缩等主要问题。从强化流域水资源统一调度、强化水资源刚性约束、强化地下水综合治理、强化河湖管理4个方面,总结梳理了水利部松辽水利委员会为实现西辽河干流全线通水和流域生态复苏采取的主要措施。2020年以来,特别是2024年春季调度实施后,西辽河取得了有水河段和有水时长逐年增加、有效回补地下水等生态复苏进展。针对西辽河全面复苏,提出加快实施河道综合整治、优化站网建设与强化站网管理、加强产汇流规律等基础性研究、推动实施跨流域生态补水等对策。

太阳能驱动闭式转轮除湿空调系统性能研究

为解决传统开式转轮除湿空调系统再生排风能量浪费的问题,本文提出了可高效回收再生排风空气显热和潜热的太阳能驱动闭式转轮除湿空调系统,利用TRNSYS软件对系统进行建模,模拟研究了冷水流量比和新风比对系统性能的影响和系统动态性能,并对模拟的准确性进行实验验证。结果表明:模拟结果与实验结果的相对误差最大为±9.8%。太阳能驱动闭式转轮除湿空调系统的最优冷水流量比为1∶5∶4。系统在广州地区整个制冷季(6月1日—9月30日)平均电力COP_(e)为2.4,平均热力COP_(th)为2.1,累计取水量为25.66 t,热回收量为9.70 MW。相比于太阳能驱动开式转轮除湿空调系统,太阳能驱动闭式转轮除湿空调系统平均COP_(e)和COP_(th)分别提高42.1%和69.2%,CO_(2)排放量减少29.3%。

日本落叶松胚状体干化处理对萌发的影响

[目的]提高日本落叶松胚状体的萌发能力,优化日本落叶松良种繁育技术。[方法]本研究根据子叶数量和胚轴形态,对胚状体进行分类,并分别统计其萌发率;利用“滤纸容器法”对类型Ⅰ胚状体进行干化处理,统计其萌发情况。[结果]胚状体分为10种类型。类型Ⅰ胚状体萌发率为4.48%,其余类型胚状体难以萌发。干化处理14 d后,类型Ⅰ胚状体萌发率提高到69.43%,且具有干化响应的胚状体更易萌发。[结论]本研究表明日本落叶松胚状体干化处理后萌发率明显提高,为该物种良种繁育提供依据。

5个群体克氏原螯虾生长和养殖生态适应性比较分析

为探明不同群体克氏原螯虾生长和养殖生态适应性,2020年自江苏滆湖、兴化、建湖,安徽芜湖和湖北监利引进5个克氏原螯虾养殖群体,2021年在安徽芜湖同期繁育后,比较分析不同群体克氏原螯虾苗在同等养殖条件下生长性状、入塘扩散速率、爬行速率及耐干露等生态适应性。试验结果显示:5月雌、雄个体体长、体质量均表现为滆湖群体[雌:(7.52±0.15)cm、(13.4±0.85)g;雄:(7.53±0.12)cm、(14.25±0.90)g]最优。5月除芜湖群体外,各群体雄性个体在体长、体质量上显著大于雌性;建湖群体在3—4月体长、体质量增长率最大(分别为41%、167%),芜湖群体在4—5月体长、体质量增长率最大(分别为24%、83%)。5月各群体雌性腹部长占体长比例均大于雄性。且5月滆湖群体成活率最高为59.33%,监利群体最低为50.67%。入塘扩散速率依次为建湖>兴化>滆湖>监利>芜湖,建湖、兴化群体显著优于其他3个群体组,扩散最快的建湖群体时间为(291.67±25.43)s,最慢的芜湖群体为(661.33±32.94)s;各群体间爬行速率无显著性差异。干露试验表明,幼虾的干露时间不宜超过18 h,干露48 h存活率依次为芜湖>滆湖>兴化>监利>建湖,芜湖群体存活率最高,为(87.78±1.11)%,建湖群体最低,为(68.89±1.92)%。试验结果可为不同群体克氏原螯虾生长性能及生态适应性评价提供参考,为进一步的选育奠定基础。

Performance analysis of three-stage liquid desiccant deep dehumidification processor driven by heat pump

A new type of a heat pump driven three-stage lithium bromide liquid desiccant deep dehumidification processor is presented,which can dehumidify the outdoor humid air to a rather dry state,even when there is no available indoor exhaust air.The test results show that with an outdoor air temperature of 28 to 31 ℃ and an outdoor air humidity ratio of 11 to 14 g/kg,the supply air temperature and the supply air humidity ratio are 1.6 to 2.6 ℃ and 2.6 to 3.0 g/kg,respectively,and the coefficient of performance（COP）of the processor is 1.8.During the test,a liquid pipeline link problem leading to mixture losses of hot and cold liquid desiccants is found.These pipelines are modified.Then,the performance of the modified processor is investigated.And the experimental results show that with an outdoor air temperature of 25 to 32 ℃ and an outdoor air humidity ratio of 18 to 21 g/kg,the supply air temperature and the supply air humidity ratio are 3.2 to 4.0 ℃ and 3.4 to 3.6 g/kg,respectively,and the COP is 2.8.Finally,a mathematical model of the processor is established.The comparison of the simulation results and the test results of the processor exhibits that the pipeline modification improves the performance by about 20%.

Properties of Advanced Adsorbent for Solid Desiccant Cooling

Characteristics of 13x molecular sieve, silica gel and DH 5 and DH 7 prepared by authors, were investigated for the solid desiccant cooling system. The adsorption isotherms of DH 5 and DH 7 were experimentally determined. The performance parameters of adsorption capacity, air humidity, regeneration temperature and cooling volume were tested and discussed in detail. The results show that the properties of new adsorbents DH 5 and DH 7 on desiccant cooling are much better than those of common desiccants. The maximum adsorption volumes of water on DH 5 and DH 7 are 0.72?kg/kg and 0.73 ?kg/kg, respectively. The desiccant cooling volumes of DH 7and DH 5 are 2.2 and 1.3 times larger than those of silica gel and 13x(molecular sieve), respectively, after regeneration at 100?℃. The cooling volume per mass unit of DH 5 is 1.9 times larger that of 13x.

数据中心用太阳能与热泵互补转轮除湿蒸发冷却系统性能研究

针对数据中心蒸发冷却技术受限于环境湿球温度的问题,文章构建了一种太阳能与热泵互补转轮除湿蒸发冷却系统,该系统利用光伏组件发电余热提供的热能,与热泵系统互补驱动转轮除湿再生。系统根据室外气象条件可实现新风、蒸发冷却和除湿+蒸发冷却3种运行模式。应用TRNSYS软件模拟上海、广州和昆明3个典型地区数据中心的系统热力、电力及能耗特性。结果表明:在上海、广州和昆明地区典型日除湿+蒸发冷却模式下,转轮除湿预处理分别使空气湿球温度平均降低了10.9,11.6,10.3℃。在上海、广州和昆明地区典型月系统平均COP值分别为4.9,5.1,3.6,最大瞬时COP达到12.1,11.4,8.1。

Desiccation Alters the Stability and Distribution of Pea Seed_borne Mosaic Virus in Pea (Pisum sativum) Cotyledon Cells

As a seed transmitted pathogen, pea seed_borne mosaic virus (PSbMV) not only replicates in embryonic cells but can also withstand seed desiccation. To understand the mechanism of PSbMV tolerance to seed desiccation, the authors compared the stability of viral coat protein (CP) and the distribution of viral particles in the cotyledon cells of pea (Pisum sativum L.) embryos collected before and after the dehydration process. Before dehydration, when the embryo was fresh and immature, degradation of CP was observed and a predominantly perinuclear distribution of viral particles in the cotyledon cells was evident. After dehydration, when the embryo was dry and mature, degradation of CP did not occur and the perinuclear viral distribution disappeared. Instead, aggregates containing PSbMV CP were found in the cytoplasm. Electron microscopy showed that these aggregates were composed of PSbMV particles. The formation of PSbMV particle aggregates is apparently triggered by seed dehydration and may be favorable to the virus survival in the desiccated embryonic cells.

非饱和土干缩开裂分析的近场动力学模拟

非饱和土失水收缩变形是一种水力耦合现象,其诱发的开裂问题严重削弱了土体的水力和力学特性,造成各种潜在的自然灾害.相对于饱和土体,非饱和土的失水收缩机制更为复杂,受到广泛关注.为此,提出了一种考虑水-力耦合作用效应的键型近场动力学(PD)模型,探究由于水分变化引起的非饱和土体变形开裂特征.在该模型中,非饱和土扩散方程由近场动力学微分算子进行重构,键型近场动力学运动方程采用改进的微弹性模量.然后提出了一种显-隐式混合算法,扩散方程采用显式差分格式求解,运动方程采用隐式整体格式求解,有效避免了两类方程在同一显式格式下时间步不协调的问题.通过非饱和土块干燥收缩变形和三维土盘干燥开裂的算例分析,验证了模型和算法的有效性.研究结果表明,所建立的模型和算法能较好地捕捉非饱和土失水收缩开裂的过程.

盐分对水分蒸发和土壤裂隙发育的影响

揭示盐碱土壤干燥开裂机理可为干旱半干旱盐碱地区基于裂缝网络的精量灌溉制度的制定提供理论基础。通过设置5种土壤含盐量(0、0.3%、0.6%、1%、2%,分别记作CK、T3、T6、T10、T20)处理,开展恒温土壤蒸发试验,探究含盐量对土壤蒸发过程的影响,并结合数字图像处理技术对蒸发过程中土壤干缩裂缝网络几何形态特征进行定量分析。结果表明:(1)不同处理蒸发过程具有相似性,即蒸发过程均包含一个线性阶段和一个非线性阶段,但各处理蒸发阶段占总蒸发阶段的比重不同,T20处理最早进入减速率阶段,说明盐分导致土壤渗透性减弱。(2)累积蒸发量随土壤含盐量的增加而降低,即CK>T3>T6>T10>T20,表明盐分可以抑制土壤蒸发。(3)随着土壤含盐量的增加,开裂含水量不断降低,土壤裂隙面积和长度逐渐减小随后趋于稳定。水分蒸发和表面开裂之间的相互作用表现为水分流失过程中游离Na+对土壤颗粒的化学影响和沉淀Na 2SO 4晶体对土壤孔隙的物理影响。(4)相关分析表明,累积蒸发量与土壤开裂水平呈正相关关系,含水量与土壤开裂水平呈负相关关系,且累积蒸发量与裂缝参数的相关程度整体高于土壤含水量与裂缝参数的相关程度。

黄土塬区不同土地利用方式10 m剖面土壤水分年际和季节动态特征

为揭示黄土高原南部塬区不同土地利用方式土壤水分时空变化特征,2014—2022年间采用土壤温湿度自动观测系统对苜蓿地、休闲地、高产农田、低产农田0—10 m剖面21层的土壤含水量进行了定位监测,并探究了其时空变化的影响因素。结果表明:4种土地利用方式中,由于多年生苜蓿地根系强吸水效应,其平均土壤含水量显著小于其他3种土地利用方式;随着土层深度的增加,苜蓿地土壤含水量先减小后增大,其他3种利用方式土壤含水量大致呈增大趋势;在季节变化特征上,土壤水分季节性干湿交替层分别为0—2 m、0—1 m、0—3 m、0—1 m,最小值和最大值分别出现在1—2月和9—11月;年尺度上,苜蓿地土壤含水量变异最大,高产农田次之,低产农田和休闲地变异性最小;就长期动态而言,土壤干层厚度和储水量变化与降水年际分布密切相关,2014—2022年各土地利用方式年均土壤储水量呈现增大趋势,2019、2021两丰水年份苜蓿地储水量增幅明显,降水补给深度可达4 m;相关性分析表明,土地利用方式、土层深度和黏粒含量为影响土壤含水量的关键因子。研究结果可为黄土高原深层剖面土壤水分观测和模拟提供数据支撑。

考虑毛细与吸附作用的黏土干缩开裂过程离散元模拟

黏土干缩开裂过程中土颗粒间的作用非常复杂,导致难以从颗粒层面对干缩裂缝的形成机理开展定量研究。基于非饱和土中的吸应力曲线,明确区分黏土中的毛细与吸附作用,在此基础上建立考虑黏土颗粒间吸引力随含水率变化的离散元接触模型,开展黏土干缩开裂的数值模拟,并与室内试验结果进行对比。结果表明,数值模拟得到的裂缝形态、裂缝发育历程、土样应变均与室内试验较为吻合,验证了离散元接触模型的可靠性。对模拟结果的进一步分析发现:①在黏土干缩开裂过程中,毛细与吸附作用共同发挥效果。随着含水率的降低,吸附作用的影响逐渐超过毛细作用。在吸附作用占优阶段,模拟土样的土颗粒沿裂缝分布方向的平均位移为最终位移值的73%。②土颗粒间总接触数量随含水率的降低先减少后增加。③在毛细/吸附作用占优阶段,土颗粒间的物理接触力会迅速增加并引起应力集中,土颗粒间接触因此集中断开进而形成裂缝。

热泵-低温再生转轮除湿联合干燥对白萝卜片干燥特性的影响

为探索新型转轮除湿干燥技术在白萝卜片干制领域的应用,通过实验研究了不同温度(35、40、45℃)、不同风速(1、2、3 m/s)和不同切片厚度(3、5、7 mm)下白萝卜片的干燥特性。结果表明,白萝卜片在切片厚度为5 mm和干燥风速为1 m/s的工况下,干燥温度为35℃时其干燥时间为5.5 h,随着干燥温度升高干燥时间显著缩短,45℃对应的干燥时间为4.0 h。另外随着切片厚度的减小干燥时间明显缩短,7、5、3 mm切片厚度下的干燥时间分别为6.5、4.0、2.5 h。同时提高干燥风速也可以提高萝卜片的干燥速率,风速为3 m/s的干燥速率与1 m/s的干燥速率相比可提高14%。热泵-低温再生转轮除湿联合干燥与单热泵干燥相比干燥时间缩短1.0 h,复水能力提高了6%,具有更高的干燥速率及干燥品质。另外该文通过对干燥数学模型分析得出Page模型能较好描述白萝卜片干燥过程中水分变化规律。

太阳能界面蒸发驱动溶液再生的实验研究

为进一步提高液体除湿空调溶液再生性能,提出一种基于太阳能界面蒸发的溶液再生方式。研究溶液种类、浓度对于再生速率和效率的影响,并与传统热再生及膜再生进行对比。结果表明,在一个太阳强度照射下,温度为26℃、质量浓度为40%的LiCl溶液达到0.39 kg/(m^(2)·h)的再生速率,质量浓度为80%的KCOOH溶液达到0.37 kg/(m^(2)·h)的再生速率。与传统的膜再生以及填料塔热再生相比,该方式展现了较高的再生速率,因此基于太阳能界面蒸发方式有望成为一种新型高效的溶液再生方法。

沼生栎种子失水过程中水分时空迁移规律

【目的】探究沼生栎种子失水过程中水分的动态迁移规律,为其安全运输、贮藏提供理论依据。【方法】采用自然干燥法降低种子的含水量,利用核磁共振成像技术分析失水过程中种子内部水分的迁移路径,并结合信噪比定量分析失水过程中种子各部位水分的散失情况。【结果】1)高场核磁共振成像及信噪比结果表明:新鲜种子中胚根区域、子叶中心部位水分含量较高,子叶外围区域水分相对较少;不同组织、不同部位子叶及不同部位种皮的信噪比均有差异。2)含水量降至30.0%时,胚根区域水分大幅下降,且胚根尖端失水速率最快,子叶外围水分也有所减少,而子叶中心部位水分变化不明显,失水最慢;种皮各部位水分散失速率也不同;含水量继续降至25.0%时,种子发芽率开始显著下降,此时胚根区域的水分已近乎不见,信噪比再次大幅下降,胚根下方很大一部分子叶开始变暗,3个种皮部位的信噪比均降至很低,其中合点端信噪比降幅最大,且该部位由于失水而出现皱缩现象;含水量降至10.0%时,子叶皱缩明显,只有子叶中心部位及其下方一小部分区域还存在少量水分。【结论】沼生栎种子的重要储水部位为胚根区域和子叶中心位置,失水过程中胚根尖端水分下降最快,子叶中心部位失水最慢,胚根区域水分的流失是影响种子质量下降的重要原因。