Equidistant combination wavelength screening and step-by-step phase-out method for the near-infrared spectroscopic analysis of serum urea nitrogen

We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.

Kinetic of Adsorption of Urea Nitrogen onto Chitosan Coated Dialdehyde Cellulose under Catalysis of Immobilized Urease

The adsorption of urea nitrogen onto chitosan coated dialdehyde cellulose (CDAC) under catalysis of immobilized urease in gelatin membrane (IE) was studied in batch system. The pseudo first-order and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model.

Oligosaccharide and Creatine Supplementation on Glucose and Urea Nitrogen in Blood and Serum Creatine Kinase in Basketball Athletes

Summary： The effects of oligosaccharide and creatine （Cr） supplementation on glucose, lactic acid and urea nitrogen levels in blood and activity of serum creatine kinase （CK） were explored. Twenty CUBA male athletes were divided into 4 groups： group A （supplementation of Cr alone）, group B （supplementation of oligosaccharide）, group C （supplementation of oligosaccharide and Cr） and group D （placebo control group）. By using orthogonal L4 table （2a ）, the experiment was performed. There were factors including oligosaccharide （carbohydrate, CHO）, Cr and their correlation. Each factor had two levels： supplementation and no-supplementation. The results showed that the supplementation of CliO or Cr alone, combined supplementation of CHO and Cr could significantly reduce the glucose, urea nitrogen levels in blood and serum CK activity after competition in the athletes. Moreover, the effects of combined supplementation of CHO and Cr were more satisfactory. It was concluded that supplementation of CliO and Cr could promote the recovery of physical performance and athletic abilities after athletics in basketball athletes.

PREPARATION OF UREA NITROGEN ADSORBENT OF COMPLEX TYPE AND ADSORPTION CAPACITY OF UREA NITROGEN ONTO THE ADSORBENT

The urea nitrogen adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose （CDAC） and immobilized urease in gelatin membrane （IE）, was prepared. The cellulose, the dialdehyde cellulose （DAC） and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10：1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37℃.

Patient characteristics with high or low blood urea nitrogen in upper gastrointestinal bleeding

AIM: To examine characteristics of patients with blood urea nitrogen(BUN) levels higher and lower than the normal limit.METHODS: Patient records between April 2011 and March 2014 were analyzed retrospectively. During this time, 3296 patients underwent upper endoscopy. In total, 50 male(69.2 ± 13.2 years) and 26 female(72.3 ± 10.2 years) patients were assessed. Patients were divided into two groups based on BUN levels: higher than the normal limit(21.0 mg/d L)(H) and lower thanthe normal limit(L). One-way analysis of variance was performed to reveal differences in the variables between the H and L groups. Fisher's exact test was used to compare the percentage of patients with gastric ulcer or gastric cancer in the H and L groups.RESULTS: White blood cell count was higher in the H group than in the L group(P = 0.0047). Hemoglobin level was lower in the H group than in the L group(P = 0.0307). Glycated hemoglobin was higher in the H group than in the L group(P = 0.0264). The percentage of patients with gastric ulcer was higher in the H group(P = 0.0002). The H group contained no patients with gastric cancer.CONCLUSION: Patients with BUN ≥ 21 mg/d L might have more severe upper gastrointestinal bleeding.

Global Optimization of Norris Derivative Filtering with Application for Near-Infrared Analysis of Serum Urea Nitrogen

Near-infrared (NIR) spectroscopy combined with chemometrics methods was applied to the rapid and reagent-free analysis of serum urea nitrogen (SUN). The mul-partitions modeling was performed to achieve parameter stability. A large-scale parameter cyclic and global optimization platform for Norris derivative filter (NDF) of three parameters (the derivative order: d, the number of smoothing points: s and the number of differential gaps: g) was developed with PLS regression. Meantime, the parameters’ adaptive analysis of NDF algorithm was also given, and achieved a significantly better modeling effect than one without spectral pre-processing. After eliminating the interference wavebands of saturated absorption, the modeling performance was further improved. In validation, the root mean square error (SEP), correlation coefficient (RP) for prediction and the ratio of performance to deviation (RPD) were 1.66 mmol?L-1, 0.966 and 4.7, respectively. The results showed that the high-precision analysis of SUN was feasibility based on NIR spectroscopy and Norris-PLS. The global optimization method of NDF is also expected to be applied to other analysis objects.

Predictive Value of Serum Creatinine, Blood Urea Nitrogen,Uric Acid, and β2-Microglobulin in the Evaluation of Acute Kidney Injury after Orthotopic Liver Transplantation

Background：As a major complication after orthotopic liver transplantation （OLT）,the occurrence of acute kidney injury （AKI） is frequently defined by serum creatinine （Cr）;however,the accuracy of commonly used blood urea nitrogen （BUN）,uric acid （UA）,and β2-microglobulin （β2-MG） remains to be explored.This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.Methods：Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled.The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes （KDIGO） criteria and classified by stage.Measurement data were analyzed using the t-test or Wilcoxon rank-sum test;enumerated data were analyzed using the Chi-square test or Fisher＇s exact test.Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic （ROC） curve analysis.Results：This study excluded 976 cases and analyzed 697 patients （578 men and 1 1 9 women）;the post-OLT AKI incidence was 0.409.Compared with the no-AKI group,the AKI group showed very significant differences in Model for End-stage Liver Disease score （14.74 ± 9.91 vs.11.07 ± 9.54,Z =5.404;P ＜ 0.001）,hepatic encephalopathy （45 [15.8％] vs.30 [7.3％],x2 =12.699;P ＜ 0.001）,hemofiltration （28 [9.8％] vs.0 [0.0％],x2 =42.171;P ＜ 0.001）,and 28-day mortality （23 [8.1％] vs.9 [2.2％],x2 13.323;P ＜0.001）.Moreover,mean values of Cr,BUN,UA,and β2-MG in the AKI group differed significantly at postoperative days 1,3,and 7 （all P ＜0.001）.ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 （sensitivity 80.1％,specificity 75.7％,cutoffvalue 88.23 μmol/L）,0.916 for Stage 2 （sensitivity 87.6％,specificity 82.6％,cutoff value 99.9 μmol/L）,and 0.972 for Stage 3 （sensitivity 94.1％,specificity 88.2％,cutoff value 122.90 μmol/L）.Conclusion：The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.

The role of rumen epithelial urea transport proteins in urea nitrogen salvage:A review

The symbiotic relationship between the host and the rumen microbiome plays a crucial role in ruminant physiology.One of the most important processes enabling this relationship is urea nitrogen salvaging(UNS).This process is important for both maintaining ruminant nitrogen balance and supporting production of their major energy supply,bacterially-derived short chain fatty acids(SCFA).The key step in UNS is the trans-epithelial movement of urea across the ruminal wall and this is a highly regulated process.At the molecular level,the key transport route is via the facilitative urea transporter-B2,localized to ruminal papillae epithelial layers.Additional urea transport through aquaporins(AQP),such as AQP3,is now also viewed as important.Long-term regulation of these ruminal urea transport proteins appears to mainly involve dietary fermentable carbohydrates;whereas,transepithelial urea transport is finely regulated by local conditions,such as CO_(2) levels,pH and SCFA concentration.Although the key principles of ruminal urea transport physiology are now understood,there remains much that is unknown regarding the regulatory pathways.One reason for this is the limited number of techniques currently used in many studies in the field.Therefore,future research in this area that combines a greater range of techniques could facilitate improvements to livestock efficiency,and potentially,reductions in the levels of waste nitrogen entering the environment.

Effects of controlled-release urea application on the growth, yield and nitrogen recovery efficiency of cotton

Field experiments were conducted to study the effects of the controlled release urea (CRU) application on growth yield and nitrogen recovery efficiency of cotton in the main cotton zone of the Yangtze River basin in 2010. Different nitrogen levels were set in order to determine the suitable dosage of CRU on cotton. The special purpose was to provide evidence for the CRU application in cotton fields. The results show that the application of CRU promotes the growth of cotton significantly and enhances the nitrogen supply in the whole period. Compared to the treatment with total N as base fertilizer (UB), the bod, flower, little bolls and total bolls are increased significantly. There are no significant differences in the yield between the CRU treatment and the treatment of controlled release urea and urea combined application (60%CRU + 40%U), but an increase by 12.38%-22.67% compared to the UB treatment, and an increase by 4.49%-7.23% compared to the treatments of total N split application (UD). The nitrogen uptake of CRU treatment was significantly increased by 13.01%-48.32% and 30.27%-13.01% than UB treatment and UD treatment, respectively. The nutrient recovery efficiency of CRU treatment is increased by 16.42-20.59, 5.92-11.29 and 4.22-12.59 percentage points compared to the UB treatment, UD treatment and 60%CRU + 40%U treatment, respectively. In this study, there was a good linearity relationship between the cotton yield and amount of CRU in Wuxue site. The yield of cotton response to amount of CRU could be described by the model of linear plus plateau in Jingzhou site.

Nitrogen deposition and release pattern of slow release fertiliser made from urea-impregnated oil palm frond and rubberwood chips

The fertiliser industry faces a continuing challenge to improve the efficiency of their products,particularly of nitrogenous fertilisers,and to minimise adverse impacts.Therefore,a new slow release fertilizer,ureaimpregnated woodchips from tropical plant biomass(oil palm frond and rubberwood),was developed.The morphology of the impregnated woodchips was investigated by scanning electron microscopy and the success of impregnation of urea and nitrogen deposition into the woodchips was confirmed by energy dispersive X-ray spectrometry.When nitrogen release patterns from impregnated woodchips fertiliser were simulated using a soil solution and distilled water as leaching solutions in a static condition for 768 h,release was slow and steady,although the release rate was lower in distilled water than in the soil solution.

Urea hydrolysis and recovery of nitrogen and phosphorous as MAP from stale human urine

Laboratory-scale tests for magnesium ammonium phosphate（MAP）precipitation following urea hydrolysis of human urine were conducted using orthogonal experiment design.The effects of initial pH,temperature and the volumetric ratios of stale urine to fresh urine,on urea hydrolysis in urine were studied to determine the final hydrolysis time to recover most nitrogen from separated human urine by MAP.With a volumetric ratio of stale to fresh urine>10% and at temperature≥20℃,urea hydrolysis could be completed in two days.Alkaline pH inhibited urea hydrolysis progress.The final pH values were all around 9.0 following urine hydrolysis,while the suspension pH might act as an indicator to detect the start and extent of urea hydrolysis.Over 95% of ammonium nitrogen and over 85% of phosphorus from hydrolyzed urine as MAP precipitate were obtained using MgCl;·6H;O and Na;HPO;·12H;O as precipitation agents at pH 8.5,molar ratio of Mg;:NH;-N:PO;-P at（1.2-1.3）:1:1,mixing speed of 120 r/min,and precipitation time and reaction time of 3 h and 15 min,respectively.The precipitate has a structure resembling pure MAP crystal.

Reducing Nitrogen Loss in Subsurface Tile Drainage Water with Managed Drainage and Polymer-Coated Urea in a River Bottom Soil

Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration.

Study on Membrane Microstructures and Characteristics of Infrared Spectra and Nitrogen Release of Solid-Liquid Reaction Coated Urea

The membrane microstructures and the mechanism of two coated ureas formed through solid- liquid reaction were observed by scanning electron microscope and infrared spectra, the relation of the structural characteristics with the nitrogen release feature was also discussed by combining with nitrogen dissolution in water. The results showed that the membranes were made of solid particles tightly connected to each other and were piled up layer by layer through liquid glue. Porosity and aperture of membrane were determined by compactness of piled layers and the particles in a single layer and also related to the characteristics of coating materials. Research of the infrared spectra of membrane, made of a solid powder and a liquid glue, proved that O-H on the solid surface was bonded with the double bond of the liquid glue, thus forming membrane and keeping it stable. It was found that the two coated ureas showed obvious differences in nitrogen releasing due to their membrane structures, the porosity and aperture of membrane were the critical factors for nitrogen releasing.

Cu、Mn、Ce改性V_2O_5-WO_3/TiO_2/堇青石催化剂Urea-SCR脱除NO

采用硅胶为黏结剂,在堇青石蜂窝陶瓷上以涂覆法依次负载Cu、Mn、Ce改性的纳米TiO2粉末、W改性的V2O5粉末得到复合催化剂,在120～550℃用尿素选择性催化还原(Urea-SCR)氮氧化物时显示良好活性。与商业催化剂V2O5-WO3/TiO2相比,添加Cu、Mn、Ce后,催化剂脱硝活性显著提高,活性温度窗口明显拓宽。结果表明,催化剂的高活性与催化剂表面适度的酸碱性、高比值的V4+/V5+以及良好的氧化还原性能和锐钛矿相的TiO2、丰富的表面裂纹的存在等因素有关。

基于Urea-SCR技术的V-W/Ti基催化剂在车用柴油机上的应用

在小样评价试验台上对制备的适合于车用柴油机SCR技术的V2O5-WO3/TiO2催化剂进行了性能试验,并同国外成熟催化剂的性能进行了对比,结果表明:试验催化剂的催化性能达到了与国外成熟催化剂相似的水平。在此基础上,按照ESC和ETC测试方法和规程对2种催化剂进行了发动机台架排放试验,结果显示,试验柴油机配装采用试验催化剂的SCR催化转化器后,其主要有害排放物测量值低于我国第Ⅳ阶段排放法规的限值,这表明催化剂的配制达到了预定目标的要求。

Comparative effects of nitrogen application on growth and nitrogen use in a winter wheat/summer maize rotation system

The application of fertilizer in agricultural production has become universally common for achieving high crop yields and economic benefits, but it has potential impacts on food safety, energy crisis and environmental pollution. Optimal management of fertilization is thus necessary for maintaining sustainable agriculture. Two-year（2013–2015） field experiment was conducted, in Yangling（108°24′E, 34°20′N, and 521 m a.s.l.）, Shaanxi Province, China, to explore the effects of different nitrogen（N） applications on biomass accumulation, crop N uptake, nitrate N（NO_3~–-N） distribution, yield, and N use with a winter wheat/summer maize rotation system. The N applications consisted of conventional urea（U）（at 80（U80）, 160（U160）, and 240（U240） kg N ha^（–1）; 40% applied as a basal fertilizer and 60% top-dressed at jointing stage） and controlled-release urea（CRU）（at 60（C60）, 120（C120）, 180（C180）, and 240（C240） kg N ha~（^（–1））; all applied as a basal fertilizer） with no N application as a control（CK）. The continuous release of N from CRU matched well with the N demands of crop throughout entire growing stages. Soil NO_3~–-N content varied less and peaked shallower in CRU than that in urea treatments. The differences, however, were smaller in winter wheat than that in summer maize seasons. The average yield of summer maize was the highest in C120 in CRU treatments and in U160 in urea treatments, and apparent N use efficiency（NUE） and N agronomic efficiency（NAE） were higher in C120 than in U160 by averages of 22.67 and 41.91%, respectively. The average yield of winter wheat was the highest in C180 in CRU treatments and in U240 in urea treatments with C180 increasing NUE and NAE by averages of 14.89 and 35.62% over U240, respectively. The annual yields under the two N fertilizers were the highest in C120 and U160. The results suggested that CRU as a basal fertilizer once could be a promising alternative of urea as split application in semiarid areas.

基于模型的柴油机Urea-SCR系统闭环控制策略仿真

针对某型柴油机的尿素选择性催化还原(Urea-SCR)系统,在相关SCR化学反应特性试验的基础上,考虑到NH_3泄漏引起的NO_x传感器交叉敏感问题,采用Matlab/Simulink建立了基于模型的SCR闭环控制策略,主要包括动态床温估算模型、起喷温度控制模型、基于NO_x传感器的原机NO_x排放估算模型、空速计算子模型、目标转化效率修正模型、尿素水溶液换算子模型、NH_3泄漏峰值修正以及储氨修正模型等.在此基础上搭建了基于Simulink和GT-Power的耦合仿真平台,并对SCR控制策略进行模型验证.结果表明:柴油机最终NO_x排放为1.92,g/(k W·h),NH_3泄漏的平均体积分数值为9.26×10^(-6),能达到国Ⅴ排放标准.

基于NO_x传感器的Urea-SCR系统氨闭环控制策略

考虑到氨闭环控制中NH_3传感器成本高的问题,针对基于氮氧化物(NO_x)传感器的尿素选择性催化还原(Urea-SCR)系统氨闭环控制策略进行了研究,以Matlab/Simulink软件为仿真平台建立了前馈控制模型、反馈控制模型、催化器模型和NO_x传感器模型;考虑到NO_x传感器对NH_3的交叉敏感特性,通过扩展卡尔曼滤波(EKF)算法,可根据NO_x传感器信号对催化器下游NH_3泄漏量进行估计;在3个典型工况下采用不同的尿素喷射量进行试验,根据试验数据用非线性最小二乘法对催化器模型进行了参数辨识;在欧洲瞬态测试循环(ETC)下进行了试验,并与模型仿真结果进行对比.结果表明:模型能较好地预测催化器下游NO排放和NH_3泄漏情况,且该控制策略在仿真和试验条件下均能将催化器下游NO排放控制在2,g/(k W·h)以下,NH_3体积分数控制在9×10^(-6)左右.

ProGRP、CYFRA21-1、RBP、Urea、Cr联合检测在肾功能不全患者中的应用价值

目的评估胃泌素释放肽前体(ProGRP)、细胞角蛋白19片段(CYFRA21-1)、视黄醇结合蛋白(RBP)、尿素氮(Urea)、肌酐(Cr)与肾功能的关系,探讨以上指标联合应用在肾功能不全患者中的临床意义。方法收集2017年1月至2019年12月南京医科大学第一附属医院肾科门诊、住院患者共107例,分别检测ProGRP、CYFRA21-1、RBP、Urea、Cr水平,并计算得到肾小球滤过率估计值(eGFR),并分析上述检测项目单独检测和联合检测的阳性率。依据eGFR值将患者分为5期。采用SPSS22.0软件进行统计分析,分析ProGRP、CYFRA21-1、RBP、Urea与Cr、eGFR的相关关系,并对不同期的ProGRP、CYFRA21-1、RBP、Urea水平进行比较。结果ProGRP、CYFRA21-1、RBP、Urea分别与eGFR呈负相关(r=-0.726、-0.557、-0.813、-0.745,P<0.05),与Cr呈正相关(r=0.821、0.452、0.807、0.773,P<0.05)。各期ProGRP、CYFRA21-1、RBP、Urea随肾功能水平下降而逐渐升高。各期ProGRP、CYFRA21-1、RBP、Urea水平比较,差异有统计学意义(P<0.05)。肾功能不全患者中联合检测阳性率高于分别单独检测ProGRP、CYFRA21-1、RBP、Urea、Cr,差异有统计学意义(P<0.05)。结论本研究探讨了ProGRP、CYFRA21-1、RBP、Urea、Cr与肾功能的关系,发现这5个指标对于诊断肾功能不全患者具有重要意义,同时随着肾脏疾病的进展,这5个指标水平明显升高,联合检测阳性率高于单项检测阳性率,预示着这五个指标联合检测可能可以作为监测肾功能的指标。

Influence of Organic and Inorganic Nitrogen on Grain Yield andYield Components of Hybrid Rice in Northwestern Pakistan

Field experiments were conducted to assess the impact of various organic sources, inorganicnitrogen （N） and the different combinations of inorganic N （urea） ＋ organic source on the yieldcomponents （YC） and grain yield （GY） of hybrid rice （Oryza sativa L., Pukhraj） under rice-wheat system.The experiments were conducted at Batkhela （Malakand）, Northwestern Pakistan, in 2011 and 2012.Our results revealed that YC and GY ranked first for the hybrid rice when applied with sole inorganic N（urea）, followed by the application of N in mixture （urea ＋ organic sources）, while the control plots （no Napplied） ranked in the bottom. Among the six organic sources （three animal manures： poultry, sheepand cattle; three crop residues： onion, berseem and wheat）, application of N in the form of poultrymanure was superior in terms of higher YC and GY. When applying 120 kg/hm2 N source, 75% N fromurea ＋ 25% N from organic source resulted in higher YC and GY in 2011, while applying 50% N fromurea ＋ 50% N from organic sources caused higher YC and GY in 2012. Therefore, the combinedapplication of N sources in the form of urea ＋ organic source can produce good performances in termsof higher YC and GY of rice under rice-wheat cropping system.