Use of Systemic Blood Urea Nitrogen Levels Obtained 30 Minutes before the End of Hemodialysis to Portray Equilibrated,Postdialysis Blood Urea Nitrogen Values

Blood urea nitrogen (BUN) levels obtained at 30 minutes before the end of dialysis were found to be closely similar to equilibrated, postdialysis BUN values obtained 30 minutes after the end of dialysis. Because of this similarity, the former BUN values can be used to derive equilibrated urea reduction ratio, or equilibrated Kt/V instead.     

尿素法制备纳米氮化锆粉体

利用尿素为固体氮源, 通过尿素分子与ZrCl₄、ZrOCl₂·8H₂O无机锆盐发生络合反应得到Z-U和ZO-U两种ZrN陶瓷的前驱体, 两种前驱体在较低温度下热裂解都可以得到ZrN陶瓷粉体。使用FT-IR对前驱体分子进行了结构分析, 采用TG-DTA跟踪了前驱体的热裂解过程, 并通过XRD和SEM对最终热裂解获得的ZrN产物进行了表征, 探讨了不同锆源制备前驱体的热裂解反应历程及其对产物ZrN的影响。结果显示: 结晶水的存在对络合反应有较大影响, 从而造成两种前驱体分子结构上存在较大差异; 尽管热裂解反应历程相似, 由于前驱体分子结构不同, 获得的ZrN粉体在纯度和形貌上存在较大差异; Z-U前驱体更容易得到纯度高的ZrN纳米粉体。     

尿素浆体的制备及其流动特性研究

相变蓄冷浆体材料具有良好的流动性与高蓄冷密度,既可以充当蓄冷材料又可以作为载冷剂输送冷量。冰浆是一种安全高效的蓄冷介质,已广泛应用于蓄冷空调。然而冰浆制备温度低,限制其在空调系统中的能源利用效率。研究发现,对高质量浓度尿素溶液降温冷却可以制备尿素浆体,相变温度范围覆盖空调工况,且相变潜热较高,具有应用潜力。本文针对尿素溶液的热物性和尿素浆体的流动性能进行了实验研究,结果表明：质量浓度为43%~48%的尿素溶液的相变温度为5~12 ℃,潜热为213.7~223.2 J/g;尿素溶液（C＞32.5%）在液相线处密度随溶液质量浓度的增大而增大,运动黏度变化则相反;尿素浆体流动特性受固相率、Re的影响,不同工况下呈涨塑性流体特征。     

改性硝酸脲作工业炸药敏化剂的研究

根据改性硝酸脲的性质，提出由改性硝酸脲作工业炸药敏化剂较梯恩梯有许多优点，并测试了由改性硝酸脲作敏化剂生产的工业炸药的性能。结果认为该炸药具有摩擦感度和撞击感度低，威力与铵梯炸药相同，成本低的优点。     

Effect of Dehydration and Urea on Stability of Homosulfamine in Solid States

In the presence of urea in solid states, the stability of unpulverized homosulfamine hydrate (phase I; UHH) is significantly decreased whereas that of unpulverized homosulfamine anhydrate (UHA) is not. The stability of UHH is decreased slightly more by pulverization (PHH). The major objective of this study was to investigate the effects of urea, dehydration, and pulverization on the stability of homosulfamine in solid states. Binary mixtures of UHH and urea, PHH and urea, and UHA and urea in a ratio of 1:1 (wt/wt) were prepared as physical mixtures and were analyzed by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and Fourier transform infrared (FTIR) spectroscopy to study their appearance and structural changes before and after storage. PXRD analysis revealed that physical mixtures comprising UHH and urea and PHH and urea have the same diffraction pattern as that of the mixture of UHA and urea after preparation. The dehydration rate of the crystal water of UHH was accelerated by the presence of urea in addition to pulverization. Moreover, the PXRD patterns of the physical mixtures of UHH/urea and PHH/urea were significantly altered during storage, whereas that of UHA/urea was not, which was consistent with the SEM and FTIR results. The particle shape and appearance of UHH varied significantly as a result of pulverization. The stability of homosulfamine was influenced not only by the presence of urea and dehydration but also by the surface state and particle size of the crystalline form.     

Construction of Nitrogen-Doped Biphasic Transition-Metal Sulfide Nanosheet Electrode for Energy-Efficient Hydrogen Production via Urea Electrolysis

Urea-assisted hybrid water splitting is a promising technology for hydrogen (H₂) production, but the lack of cost-effective electrocatalysts hinders its extensive application. Herein, it is reported that Nitrogen-doped Co₉S₈/Ni₃S₂ hybrid nanosheet arrays on nickel foam (N-Co₉S₈/Ni₃S₂/NF) can act as an active and robust bifunctional catalyst for both urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), which could drive an ultrahigh current density of 400 mA cm⁻² at a low working potential of 1.47 V versus RHE for UOR, and gives a low overpotential of 111 mV to reach 10 mA cm⁻² toward HER. Further, a hybrid water electrolysis cell utilizing the synthesized N-Co₉S₈/Ni₃S₂/NF electrode as both the cathode and anode displays a low cell voltage of 1.40 V to reach 10 mA cm⁻², which can be powered by an AA battery with a nominal voltage of 1.5 V. The density functional theory (DFT) calculations decipher that N-doped heterointerfaces can synergistically optimize Gibbs free energy of hydrogen and urea, thus accelerating the catalytic kinetics of HER and UOR. This work significantly advances the development of the promising cobalt–nickel-based sulfide as a bifunctional electrocatalyst for energy-saving electrolytic H₂ production and urea-rich innocent wastewater treatment.     

新型尿素吸附剂——果胶铜凝胶球的吸附性能

用铜离子交联果胶制得果胶铜凝胶球,用红外光谱和扫描电镜初步表征其结构,并研究果胶铜凝胶球对尿素的吸附性能。分别考察了果胶浓度、铜离子浓度、吸附时间、温度和尿素浓度对吸附的影响。结果表明:303K时,果胶铜凝胶球对尿素的吸附反应在7h时达平衡,当果胶浓度为2.5%,氯化铜浓度为2.0%,尿素浓度为400mg/L时,吸附量为48.63mg/g。吸附等温线符合Freundlich方程,温度过高和过低对吸附均不利。     

SBP/P(AA-co-AM)复合高吸水树脂的溶胀及尿素缓释性能研究

以废弃沙棘枝糠粉为原料,丙烯酸(AA)和丙烯酰胺(AM)为单体,通过溶液聚合法合成了一种SBP/P(AA-co-AM)复合高吸水树脂。采用FT-IR和SEM对样品的结构和表面形貌进行表征。溶胀性能测试研究表明SBP/P(AA-co-AM)复合高吸水树脂在去离子水和0.9%NaCl溶液中的吸水倍率分别可达130.0g/g和25.0g/g,在60℃下仍具有较好的保水性能。以SBP/P(AA-co-AM)复合高吸水树脂在0.5mol/L的尿素溶液中平衡溶胀后所得水凝胶(SRU)作为尿素在水溶液中的释放材料,实验考察了释放环境对尿素释放过程的影响,结果表明溶液介质温度越高,尿素的释放越快;酸性或碱性介质中,尿素的释放速率加快。     

Nickel-Doped Carbon Dots as an Efficient and Stable Electrocatalyst for Urea Oxidation

Urea is a typical contaminant present in wastewater which may cause severe environmental problems. Electrochemical catalytic oxidation of urea has emerged as an efficient approach to solve this problem. Nevertheless, the current nickel-based catalysts (e.g., nickel hydroxide/sulfides) feature a high metal content. It not only lowers the utilization efficiency of nickel but also causes secondary pollution to the environment. Here, nickel-doped carbon dots (Ni-CDs) with an excellent and stable catalytic activity for the electrocatalytic urea oxidation reaction (UOR) are reported. Specifically, carbon dots (CDs) with abundant functional groups are synthesized by a one-pot hydrothermal method and then Ni-CDs with a very low metal content (1.1 at%) are prepared. The Ni²⁺ sites by coordination with carboxylic groups on the CDs provide excellent electrocatalytic activity and excellent durability for the UOR, as demonstrated by an anodic current density of 100 mA cm⁻² at a potential of 1.38 V (vs RHE) and similar experimental results in practical application. To the best of knowledge, this is the first report of CDs-based materials applied for the UOR, which opens an important new area of applicability for CDs as well as broadens the scope of the materials for electrochemical catalysis of urea.     

复杂环境下64 m尿素造粒塔的爆破拆除

介绍了金陵石化64 m高尿素造粒塔的爆破拆除。该尿素造粒塔所处环境十分复杂，为保证其安全爆破拆除，不损伤四邻建筑，参考烟囱及冷却塔爆破方法，采用高切口定向爆破方案。同时，根据其自身的结构特点，采用了大切口的预处理措施。爆破结果表明：方案可行，拱形超大导向窗可用于类似工程。     

功能化脲醛树脂磁性荧光微球的制备及表征

采用化学共沉淀法制备了磁性纳米粒子Fe_3O_4,并合成出水溶性好的5(6)-羧基罗丹明衍生物。以5(6)-羧基罗丹明衍生物为荧光染料,尿素、甲醛为单体,硝酸为引发剂,Fe3O4为核,水为分散介质,制备了脲醛树脂磁性荧光微球,并通过溶胶-凝胶法在其表面引入硅羟基。用扫描电子显微镜、荧光显微镜、傅里叶变换红外光谱仪、X射线衍射仪、振动样品磁强计、热失重分析仪、荧光分光光度计对磁性荧光微球的结构形貌及磁性荧光性能进行了表征。结果表明,所制备的脲醛树脂磁性荧光微球具有良好的单分散性,粒径分布窄,荧光性能好且稳定,具有超顺磁性且磁响应性强;在微球表面成功引入了硅羟基;分散在乙醇或水中的磁性荧光微球的荧光发射光谱相对于5(6)-羧基罗丹明衍生物发生了红移。     

微波辅助软化尿素浸泡梓木弯曲工艺探讨

目的研究微波辅助加热处理条件下梓木的弯曲工艺。方法当微波处理频率一定时,分析比较梓木浸水材与尿素浸泡材的软化弯曲性能差异,探讨微波处理时间、木材初含水率以及微波处理功率等工艺因素对梓木软化效果的影响。在单因素实验基础上,采用响应面法建立二次回归模型,并对微波辅助软化弯曲工艺进行优化。结果梓木经尿素浸泡处理后弯曲性能得到明显提高,且微波处理时间、木材初含水率以及微波处理功率等工艺因素对梓木软化弯曲性能影响显著。结论当微波处理时间为2 min、初含水率为40%、微波处理功率为500 W时,梓木的最小弯曲半径比h/r能达到1/5。     

3D Hierarchical-Architectured Nanoarray Electrode for Boosted and Sustained Urea Electro-Oxidation

Exploring active and durable Ni-based materials with optimized electronic and architectural engineering to promote the urea oxidation reaction (UOR) is pivotal for the urea-related technologies. Herein a 3D self-supported hierarchical-architectured nanoarray electrode (CC/MnNi@NC) is proposed in which 1D N-doped carbon nanotubes (N-CNTs) with 0D MnNi nanoparticles (NPs) encapsulation are intertwined into 2D nanosheet aligned on the carbon cloth for prominently boosted and sustained UOR electrocatalysis. From combined experimental and theoretical investigations, Mn-alloying can regulate Ni electronic state with downshift of the d-band center, facilitating active Ni³⁺ species generation and prompting the rate-determining step (*COO intermediate desorption). Meanwhile, the micro/nano-hierarchical nanoarray configuration with N-CNTs encapsulating MnNi NPs can not only endow strong operational durability against metal corrosion/agglomeration and enrich the density of active sites, but also accelerate electron transfer, and more intriguingly, promote mass transfer as a result of desirable superhydrophilic and quasi-superaerophobic characteristics. Therefore, with such elegant integration of 0D, 1D and 2D motifs into 3D micro/nano-hierarchical architecture, the resulting CC/MnNi@NC can deliver admirable UOR performance, favorably comparable to the best-performing UOR electrocatalysts reported thus far. This work opens a fresh prospect in developing advanced electrocatalysts via electronic manipulation coupled with architectural engineering for various energy conversion technologies.     

Effect of Particle Size on Direct Compaction of Urea Fertilizer

The effect of particle size on compaction properties and characteristics of urea tablets manufactured from available urea granules (TG tablets) and ground urea powders (TP tablets) was investigated. The compaction properties, namely, plastic work, elastic work, friction work, and maximum ejection pressure were analyzed from the force-displacement profile of the compaction process. Five applied pressures ranging between 37.67 MPa and 188.35 MPa were used to compact the materials using a universal testing machine. Characteristics of the tablets tested were mechanical strength and the release of ammonium ion through dissolution test. The results demonstrated that TG tablets underwent high plastic work and elastic work but low friction work compared to the TP tablets. TG tablets released lower amount of ammonium ion compared to the TP tablets at almost all applied pressures, except at 75.34 MPa. This study provides a valuable data for evaluating the behavior of urea in the form of granules and powders during the compaction process as well as the suitability in choosing the form of raw material for the production of urea tablets.     

Effect of Low Dialysate Flow Rate on Hemodialyzer Mass Transfer Area Coefficients for Urea and Creatinine

Recent work has shown that the dialyzer mass transfer area coefficient (K_oA) for urea increases when the dialysate flow rate is increased from 500 to 800 mL/min. In this study we determined urea and creatinine clearances for two commercial dialyzers containing polysulfone hollow fibers in vitro at 37°C, a nominal blood flow rate of 300 mL/ min, and dialysate flow rates (Q_d) ranging from 100 to 800 mL/min. A standard bicarbonate dialysis solution was used in both the blood and dialysate flow pathways, and clearances were calculated from solute concentrations in the input and output flows on both the blood and dialysate sides. Urea and creatinine K_oA values, calculated from the mean of the blood and dialysate side clearances, increased (p < 0.01) with increasing Q_d over the entire range studied. The increase in both urea and creatinine K_oA with increasing Q_d was proportional to the K_oA value. These data show that changes in Q_d alter small solute clearances greater than predicted assuming a constant K_oA.     

Gold Nanomaterials in Consumer Cosmetics Nanoproducts: Analyses,Characterization, and Dermal Safety Assessment

Establishment of analytical methods of engineered nanomaterials in consumer products for their human and environmental risk assessment becomes urgent for both academic and industrial needs. Owing to the difficulties and challenges around nanomaterials in complex media, proper chemical separation and biological assays of nanomaterials from nanoproducts needs to be firstly developed. Herein, a facile and rapid method to separate and analyze gold nanomaterials in cosmetics is reported. Gold nanomaterials are successfully separated from different facial or eye creams and their physiochemical properties are analyzed by quantitative and qualitative state‐of‐the art techniques with high sensitivity or high spatial resolution. In turn, a protocol including quantification of gold by inductively coupled plasma mass spectrometry and thorough characterization of morphology, size distribution, and surface property by electron microscopes, atomic force microscope, and X‐ray photoelectron spectroscope is developed. Subsequently, the preliminary toxicity assessment indicates that gold nanomaterials in cosmetic creams have no observable toxicity to human keratinocytes even after 24 h exposure up to a concentration of 200 μg mL^?1. The environmental scanning electron microscope reveals that gold nanomaterials are mostly attached on the cell membrane. Thus, the present study provides a full analysis protocol for toxicity assessment of gold nanomaterials in consumer products (cosmetic creams).     

A Novel Urea Amperometric Biosensor Based on Secretion of Wild Winter Jasmine Petal Cells Modified on Graphite-Epoxy Composite Electrode

A new kind of amperometric biosensor was designed for detection of urea with a high selectivity, sensitivity and wide detection range based on the secretion of whole living cells of wild winter jasmine petals paste covered on a graphite-epoxy composite basic electrode surface. The petal paste from mashed fresh winter jasmine petals was tightly fixed on the basic electrode surface with teflon thin film to keep it contact with electrode surface. During the mashing process, the winter Jasmine petal cells secrete some species, which are electrochemical active and gives an oxidation peak at 0.316 V （vs. SCE） in differential pulse voltammetric curve. The interactions of secreted species with urea molecules, and results in the decrease the oxidation peak current. The oxidation peak current was decreased linearly with the logarithm of urea concentration in the range of 1.3×10^-16-4.57 ×10^-16 M with the detection limit of 1.3×10^-16 M.     

尿素改性碳纤维电场电极制备及电化学性能研究

以尿素为氮源,对碳纤维表面进行改性,制备了一种新型海洋电极,并测试了其电化学性能和电场响应性能。结果表明,碳纤维表面的含氧和含氮基团对其电化学性能具有显著的影响,与尿素反应并在450℃条件下热处理的碳纤维具有最低的内阻和最大的比电容。电化学性能的变化也直接影响碳纤维电极对的电场性能,450℃条件下热处理的碳纤维电极也具有最佳的电场性能:电极对极差稳定性降到0.1 m V/24 h左右,自噪声为2.2 n V/rt Hz@1Hz,电极对能较好地响应出1 m Hz、1 m V电场信号。     

尿素溶液制备冰浆的流动特性研究

在实际应用中,通常采用管道输送的方式将冰浆运送至待冷却区域进行热交换,因此,研究冰浆的流动特性具有重要意义.本文基于冰浆制备及流动特性测试实验台,以质量分数为5％的尿素溶液制备的冰浆为研究对象,通过可视化观测冰浆中冰粒的尺寸及分布并测量冰浆的运动黏度,分析了管径、含冰率(IPF)、流动压降以及管道摩擦阻力系数与雷诺数(...