基于不完全契约理论的水利水电工程项目治理研究

在不完全契约理论视角下，研究政府规制对水利水电工程项目治理结构的影响程度具有重要意义。为便于分析，将 水利水电工程项目的参与方分为政府与代建方和代建方与承包方两部分，通过对三者所组成的双重委托代理关系开展分析， 研究政府规制对于各参与方的治理结构产生的影响，并对如何提升政府规制效果提出了相关建议。     

Improving hydrogen production from the anaerobic digestion of waste activated sludge: Effects of cobalt and iron zero valent nanoparticles

Recently, different metallic additives have been studied to improve biohydrogen production, such as salts or oxides with iron and nickel. The results have been positive in simple systems, but there are very few studies of the use of nanoparticles of iron and cobalt in systems that use complex substrates such as sludge. In the present study, the effects on hydrogen production from anaerobic digestion of waste activated sludge by zero valent iron nanoparticles (NZVI) and cobalt (CoNP) dosage were investigated. The maximum hydrogen yields were reached with 7 mg/gVS for both additives, 5.74 and 5.40 mLH₂/gVS_added, for NZVI and CoNP, respectively. In contrast, a low yield was observed in the control reactor (1.79 mLH₂/gVS_added), representing increases of over 200%. The dosage of CoNP and NZVI decreased the redox potential and increased the volatile fatty acid concentration, mainly acetic acid. The results indicate that NZVI and CoNP stimulate the early stages of anaerobic digestion of sludge.     

污泥预处理-厌氧消化体系的能源经济性评价

在污泥的厌氧消化中，降低过程能耗与提高甲烷产量是实现污水处理系统“碳中和”的主要思路之一。热、化学、机械预处理是打破厌氧消化限速水解的有效手段，主要着眼于甲烷增产以形成更多的“碳补偿”。但从热力学角度，预处理是通过消耗电能、热能、化学能使有机物大量溶解，从而获得更多生物质能的过程，其本身作为一种能量输入形式增加了厌氧消化的能耗。以往的研究通常以污泥液相中有机物溶出、固相中有机物去除以及甲烷产量作为厌氧消化性能的评价指标，难以客观评估各类厌氧消化预处理的实际效益。本文从能源转换的角度出发，综述了各类污泥预处理方法的作用机理及对厌氧消化的抑制因子等方面的研究进展，对比了典型的热预处理、碱预处理、超声预处理及其联合处理分别在甲烷产量、净能量和净利润等指标上的研究结果，并在污泥厌氧消化效率评价基础上分析了上述预处理方法在能源和经济层面的可行性，为预处理方法和预处理条件的选择提供多维度依据。     

Using sugarcane leaves and tops for exploiting higher methane yields: An assessment study

Sugarcane leaves and tops are lignocellulosic agricultural by-products which are considered a significant input for biogas production. Their potential pretreatment by sodium hydroxide prior to co-digestion with cow manure helps increase the methane (CH₄) content, biodegradation efficiency of the lignocellulosic materials and CH₄ yield. The untreated and pretreated sugarcane leaves and tops to cow manure and water of different ratios were digested and co-digested in the 5 L reactors by semi-continuous operation with hydraulic retention time of 40 days. The pretreated sugarcane leaves and tops to cow manure at the initial prepared ratio of 100 g:100 g, in 800 mL water which was corresponding to the organic loading rate (OLR) of 0.61 kg COD/m³·day was recommended. At this ratio, the chemical oxygen demand and total volatile solids degradation efficiency was 68.80 and 72.52%, respectively, the CH₄ content was 44.52% and the CH₄ yield was 331 L/kg COD degraded. According to the results, there is an average of 3.7% deviation between the practical model based on the thermodynamic balance equations carried out using the Aspen Plus and the experimental study. The highest exergy destruction rate is found at 21 kW where the sugarcane leaves and tops, and cow manure ratio is 100 g:100 g, in 800 mL water. The highest energy and exergy efficiencies of the overall system are calculated as 45.53% and 46.02%, respectively.     

ICP-OES法测定辣条中的多种金属元素

此次试验旨在建立一种可靠的微波消解-电感耦合等离子体发射光谱(ICP-OES)法测定辣条中10种金属元素的方法。试验对仪器参数进行优化,随机购买市售50份样本,打碎混匀后,用微波消解-ICP-OES法对锰、铜、铁、铝、铅、银、镉、钼、镍、铬10种元素进行同时测定。结果表明,在优化试验条件下,各金属元素的线性关系良好,相关线性(r^2)在0.9998以上,方法的检出限为0.034~0.646 mg/kg。在加标量为0.005,0.010和0.020 mg/kg的3种梯度浓度下,回收率达到90.0%~102.0%,方法精密度RSD为0.82%~7.71%。该方法样品处理效率高,样品消解彻底,操作简单快速,谱线干扰少,线性范围宽,灵敏度高,能满足辣条样品中多种金属元素的同时测定。     

Enhancement of biogas production from sunnhemp using alkaline pretreatment

This study investigates enhancing the biogas production of sunnhemp by pretreatment, before the anaerobic digestion and co-digestion processes, to address the complex and recalcitrant structure of the plant. Fresh sunnhemp harvested at a cutting interval of 50 days is used in the study. Five systems (each with a 5 litre useable volume) are operated semi-continuously with five different ratios of the feedstock by feeding separate feedstocks every five days with a hydraulic retention time (HRT) of 40 days. The system operates at room temperature (30 °C). The study uses sunnhemp as 20% of the feedstock and also considers sunnhemp mixed with cow manure at different ratios, with the weighed sunnhemp being pretreated with dilute sodium hydroxide. Pretreatment of sunnhemp before digestion produces a methane (CH₄) yield 89% greater than that of the untreated sunnhemp. It requires 3.597 kg of dry sunnhemp to produce 1 m³ of CH₄ and the annual CH₄ yield per hectare is 19,015 m³. In the pretreatment of sunnhemp before co-digestion, the increased CH₄ yield depends on the amount of pretreated sunnhemp in the feedstocks. However, the %CH₄, the CH₄ production level and the system stability depend on the optimal ratio of the sunnhemp to cow manure. The initially prepared sunnhemp to cow manure ratio is recommended at 10 g:10 g in 80 mL of water. At this ratio, the %CH₄ and the CH₄ yield are 53.84% and 313 kg chemical oxygen demand (COD) removed, respectively, and the COD removal efficiency is 56.4%. Sunnhemp has high potential and it is worth pretreating before producing biogas. Using sunnhemp to produce biogas is recommended to decrease greenhouse gas emissions and mitigate global warming.     

Beneficial effects of three brown seaweed polysaccharides on gut microbiota and their structural characteristics: An overview

The gut microbiota appears critical in the metabolic health and anti-disease activity. In this review, we discuss three brown seaweed polysaccharides (alginate, laminarin, fucoidan) for their structural information, the digestive behaviour and the effects on gut microbiota. Bioactivities are associated with various physicochemical properties, like solubility, viscosity, hydration properties, molecular weight, monosaccharide composition, and so on. Brown seaweed polysaccharides can be completely utilised by microbes in the large bowel, and they can regulate the gut microbiota. The ultimate metabolite of these polysaccharides is mainly short-chain fatty acids, which are able to regulate the ecology of the gut microbiota by increasing the growth of beneficial bacteria and inhibiting the growth of some harmful bacteria. In addition, this article also discusses the relationship between the structure and activity of modulating the gut microbiota. Results show that polysaccharides with low molecular weight are more conductive to modulate gut microbiota.     

应用微波消解-ICP-MS法分析环境水样中的钍

采用微波消解对环境水样进行前处理、应用电感耦合等离子体质谱法(ICP-MS)快速测定环境水样中钍含量，对测量条件和微波消解条件进行了优化，并从内标的选择、检出限、精密度、准确度、回收率以及实际样品测量等方面对结果进行分析。结果表明：以209Bi为内标分析水中钍时，测量结果的相对偏差最小，为0.2%～1.3%；该方法检出限为0.003 μg/L；考察了4个浓度水平下的方法精密度，相对标准偏差（s_r）均小于6.0%(n=6)；进行了3个不同浓度水平下的标准物质测量和加标回收率实验，测定值与标准值基本吻合，加标回收率为93.4%～106.2%；对20个实际环境水样中钍质量浓度进行了测量，测定结果在2016年测量值范围之内，验证了该法测量环境水样中钍含量的实用性。     

微波消解-原子吸收法应用于核级树脂锂型转型率的分析研究

常规核级离子交换树脂锂型转型率的测量采用将离子交换树脂中的锂用酸淋洗后测量锂浓度，再计算锂型转型率，存在分析时间长、分析结果偏低等不足。本文采用微波消解-原子吸收法测量核级离子交换树脂的锂型转型率，利用微波消解实现树脂的完全消解，利用原子吸收仪测量锂浓度，结合氢型树脂湿基工作交换容量计算离子交换树脂的锂型转型率，实现离子交换树脂锂型转型率的准确测量。分析结果表明，锂浓度加标回收率为99%，相对标准偏差为0.97%（n=7），锂型转型率达99.20%。方法具有离子交换树脂使用量少、分析结果准确等优点，可用于核级离子交换树脂锂型转型率的测量。