Enhanced nitrite electroreduction to ammonia via interfacial dual-site adsorption

The nitrite(NO_(2)^(−))to ammonia(NH3)electroreduction reaction(NO_(2)^(−)RR)would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction(HER).A key to improving the NH_(3) selectivity is to facilitate adsorption and activation of NO_(2)^(−),which is generally undesirable in unitary species.In this work,an efficient NO_(2)^(−)RR catalyst is constructed by cooperating Pd with In2O3,in which NO_(2)^(−)could adsorb on interfacial dual-site through“Pd–N–O–In”linkage,leading to strengthened NO_(2)^(−)adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3.Moreover,the Pd/In_(2)O_(3)composite exhibits moderate H^(*)adsorption,which may facilitate protonation kinetics while inhibiting competitive HER.As a result,it exhibits a fairly high NH_(3)yield rate of 622.76 mmol h^(−1)g^(−1)cat with a Faradaic efficiency(FE)of 95.72%,good selectivity of 91.96%,and cycling stability towards the NO_(2)^(−)RR,surpassing unitary In_(2)O_(3)and Pd/C electrocatalysts.Besides,computed results indicate that NH_(3)production on Pd/In_(2)O_(3)follows the deoxidation to hydrogenation pathway.This work highlights the significance of H^(*)and NO_(2)^(−)adsorption modulation and N=O activation in NO_(2)^(−)RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.

Promoting electroreduction of nitrite to ammonia over electron-deficient Pd modulated by rectifying Schottky contacts

Electrochemical nitrite reduction reaction(NO_(2)^(-)RR) is a potential sustainable route for regulating the nitrogen cycle and ambient ammonia(NH_(3)) synthesis.However,it remains a challenge to precisely regulate the reaction pathways and inhibit competing reactions(e.g.hydrogenolysis) for efficient and selective NH_(3) production in an aqueous solution environment.Here,we utilize the Schottky barrier-induced surface electric field to construct high-density electron-deficient Pd nanoparticles by modulating the N content in the carbon carrier to promote the enrichment and immobilization of NO_(2)^(-)on the electrode surface,which ensures the ultimate selectivity for NH_(3).With these properties,Pd@N_(0.14)C with the highest N content achieved excellent catalytic performance for the reduction of NO_(2)^(-)to NH_(3) with the 100% Faraday efficiency at-0.5 and-0.6 V vs,reversible hydrogen electrode(RHE) for NH_(3) production,which was significantly better than Pd/C and Pd@N_(x)C samples with lower N content.This study opens new avenues for rational construction of efficient electrocatalysts for nitrite removal and NH_(3) electrosynthesis.

Assessment of Nitrates and Nitrites in Borehole Water from the Southern and the Northern Region of Côte d’Ivoire (West Africa)

This study aimed to evaluate the quality of water from village boreholes by measuring physicochemical parameters such as nitrates, nitrites, and total organic carbon (TOC). Forty-five (45) village pumps from the Southern (Basse Côte) and the Northern (Korhogo) region of Cte d’Ivoire (west Africa) were sampled. Physicochemical parameters such as temperature, pH, conductivity at 25˚C, and turbidity were determined in situ, while nitrite and nitrate were analyzed according to ISO 10304-1 (2007) standard and total organic carbon (TOC) by NF EN 1484 (1997) standard. The results showed that the borehole waters of the Basse Côte and Korhogo analyzed are acidic, with an average temperature of 27.51˚C ± 0.16˚C and 29.95˚C ± 0.51˚C respectively for the Basse Côte and Korhogo regions. The borehole waters of the Basse Côtedo not contain nitrites, while those of Korhogo have average nitrite contents of 0.32 mg/l. The average nitrate rate in the waters of the Basse Côte and Korhogo are 12.08 ± 2.11 mg/l and 11.03 ± 3.18 mg/l respectively. The average TOC concentration of the waters of the Basse Côte is 1.28 ± 0.32 mg/l and that of Korhogo is 0.56 ± 0.09 mg/L. The study showed that the borehole waters of the Basse Côte and Korhogo have average temperatures between 27.4˚C and 29.95˚C with a slightly acidic pH value and acceptable salinity. The TOC concentrations obtained at the different sampling points were all below the French standard (2 mg/L) except for certains pumps of the Basse Côte. The water samples from the Basse Côte were devoid of nitrite. On the other hand, those from Korhogo revealed the presence of nitrite. Also, the borehole waters of the regions of the Basse Côte and Korhogo contain relatively high nitrate contents, presumably due to anthropometric activity. Overall, our study on the quality of drinking water showed that the waters analyzed are in compliance with international standards and safe for consumption.

Comprehensive understanding of the thriving electrocatalytic nitrate/nitrite reduction to ammonia under ambient conditions

Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.

Pueraria isoflavones inhibit XOD and GLUT9 to decrease uric acid production and promote uric acid excretion, respectively

Objective: To analyze the possible mechanism of Pueraria isoflavones inhibiting XOD and GLUT9 to reduce uric acid production and promote uric acid excretion. Methods: August 2021-April 2022, a total of forty SPF male Kunming mice were divided into the healthy group (carboxymethylcellulose sodium at a dose of 250 mg/kg), the model group (HUA mice were given carboxymethylcellulose sodium at a dose of 250 mg/kg), the low group (HUA mice were given pueraria isoflavone at a dose of 125 mg/kg), HUA mice were given pueraria isoflavones at a dose of 250 mg/kg once d frequency)and the high group (HUA mice were given pueraria isoflavones at a dose of 500 mg/kg once d frequency) dosage groups, with 8 mice in each group. The contents of uric acid (SUA), urea nitrogen (BUN) and creatinine (SCr) in serum and urine of each group were compared before and after intervention (30 d). Statistical differences of xanthine oxidase (XOD) and human glucose transporter 9(GLUT9), cy- clooxygenase- 2(COX-2), tumor necrosis factor (TNF-α) and interleukin-1 (IL-1β) contents in renal tissues of each group after intervention (30 d) were compared. Results: After intervention, kidney inflammatory factors (COX-2, TNF-α and IL-1β) in the model group were compared. Blood and urine indexes (SUA, BUN, SCr);The contents of XOD and GLUT9 were higher than those of healthy group(P<0.05). Renal inflammatory cytokines (COX-2, TNF-α and IL-1β) in low, medium and high dose groups;Blood and urine indexes (SUA, BUN, SCr);The contents of XOD and GLUT9 were lower than those of model group, and there were low > medium > high dose groups, the comparison between the two groups had statistical significance(P< 0.05). After intervention, the contents of 3 indicators in blood or urine(COX-2, TNF-α and IL-1β) all decreased compared with before intervention, and the differences in intra-group comparison were statistically significant (P<0.05). Conclusion: Pueraria isoflavones can treat HUA mice by inhibiting the expression of XOD and GLUT9, and then play a role in reducing uric acid pro- duction and promoting uric acid excretion, as well as alleviating the degree of disease inflammation.

Acquired methemoglobinemia in a third trimester puerpera and her premature infant with sodium nitrite poisoning:A case report

BACKGROUND The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit.The subsequent formation of methemoglobin(MetHb)restricts oxygen transport and utilization in the body,resulting in functional hypoxia at the tissue level.In clinical practice,a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia.Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.CASE SUMMARY A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission.Subsequently,she developed vomiting and cyanotic skin.The woman underwent orotracheal intubation,invasive mechanical ventilation(IMV),and correction of internal environment disturbance in the ICU.Her premature infant was born with a higher-than-normal MetHb level of 3.3%,and received detoxification with methylene blue and vitamin C,supplemental vitamin K1,an infusion of fresh frozen plasma,as well as respiratory support via orotracheal intubation and IMV.On day 3 after admission,the puerpera regained consciousness,evacuated the IMV,and resumed enteral nutrition.She was then transferred to the maternity ward 24 h later.On day 7 after admission,the woman recovered and was discharged without any sequelae.CONCLUSION MetHb can cross through the placental barrier.Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.

Effects of Standing Time during Pretreatment on the Nitrite Concentration Detected by Spectrophotometric Method

Food safety problems caused by excessive nitrite addition have been frequently reported and the detection of nitrite in food is particularly important. The standing time during the pretreatment of primary sample has a great influence on the concentration of nitrite tested by spectrophotometric method. In this context, three kinds of food samples are prepared, including canned mustard, canned fish and home-made pickled water. A series of standing times are placed during the sample pretreatments and the corresponding nitrite contents in these samples are detected by spectrophotometric method based on N-ethylenediamine dihydrochloride. This study aims to find out a reasonable standing time during the pretreatment of food sample, providing influence factor for precise detection of nitrite.

酚酸基纳米金修饰电极检测食品中的亚硝酸盐和亚硫酸盐

基于酚酸良好的还原性和无污染性建立酚酸基纳米金传感体系,以实现亚硝酸盐和亚硫酸盐的灵敏检测。采用不同酚酸还原氯金酸制备纳米金(Gold nanoparticles,AuNPs),通过紫外光谱和交流阻抗法获得还原效果最佳的酚酸为没食子酸(Gallic acid,GA)。利用电沉积法制备GA@AuNPs@Au电极,并由线性扫描伏安法(Linear scanning voltammetry,LSV)表征亚硝酸盐和亚硫酸盐的电化学行为。优化体系条件为:GA浓度1 mmol/L、孵育温度70℃、反应时间60 min、pH6.0磷酸盐缓冲溶液浓度0.15 mol/L。亚硝酸盐和亚硫酸盐浓度在0.001~7 mmol/L范围内与氧化峰电流分别呈良好的线性关系(R2>0.994),检出限分别为0.20μmol/L和0.24μmol/L(S/N=3)。该修饰电极的重现性和稳定性良好,可用于实际样品中亚硝酸盐和亚硫酸盐的同时测定。

术前CL-11、尿亚硝酸盐、U-HBP与肾结石术后并发尿源性脓毒症的相关性及预警意义

目的分析术前胶原凝集素-11(CL-11)、尿亚硝酸盐、尿肝素结合蛋白(U-HBP)与肾结石术后并发尿源性脓毒症(US)的相关性,并探讨其对术后并发US的预测价值及其预警意义。方法选取2021年9月至2023年6月昆明医科大学第二附属医院190例肾结石患者,根据微创经皮肾镜取石术后7 d是否并发US分为US组(n=30)和无US组(n=160)。比较两组基线资料及术前CL-11、尿亚硝酸盐、U-HBP。分析术前CL-11、尿亚硝酸盐、U-HBP与术后并发US的关系。评价术前CL-11、尿亚硝酸盐、U-HBP对术后并发US的预测效能。结果US组CL-11、尿亚硝酸盐阳性占比、U-HBP分别为(313.68±38.73)ng/mL、46.67%、(157.82±41.61)ng/mL,高于无US组的(234.00±41.25)ng/mL、12.50%、(128.59±36.38)ng/mL(P<0.05);Logistic回归分析显示,术前CL-11、尿亚硝酸盐、U-HBP是并发US的影响因素;术前CL-11、尿亚硝酸盐、U-HBP预测术后并发US的AUC依次为0.797、0.624、0.826,联合预测术后并发US的AUC为0.923,敏感度、特异度分别为90.00%和88.75%。结论肾结石术后并发US患者尿亚硝酸盐阳性占比、CL-11、U-HBP水平升高,且与术后并发US呈正相关,其对术后并发US具有一定预测价值,联合检测其水平的预测效能更优,可能作为术后并发US的预警标志物,为临床制定防控措施提供参考。

Effect of Fouling on Feeding, Oxygen Consumption and Waste Excretion of Pearl Oyster Pinctada martensii in Daya Bay Cultivation

Biofouling is a particular problem in the pearl oyster culture. It may reduce the growth and survival rates of the cultured species. Foulers are often themselves filter feeders, and are therefore potential competitors for food resource with the cultured species. Fouling organisms may also reduce the oxygen supply. A study was conducted to measure the impact of foulers on feeding oxygen consumption, and waste excretion. POM, ammonia, phosphate and oxygen concentration were measured in various treatments （cultured species, foulers）. This study showed that fouling organisms had significant effect on food uptake, oxygen consumption and waste excretion. The clearance rate, ammonia and phosphate release rate, oxygen consumption rate of the fouled pearl oyster were greater than those of the clean pearl oysters. Other foulers that settled on cages or buoys also contributed much to phytoplankton depletion, oxygen consumption and concentration increase of ammonia and phosphate in water. Therefore, this study showed us that foulers were important competitors in the pearl oyster cultivation of Daya Bay in November 2005.

果菜类蔬菜混合发酵菌种筛选及其发酵特性研究

不同类型的发酵菌株对发酵蔬菜风味的形成有不同的影响。为评估发酵蔬菜中菌株的发酵特性,筛选适用于蔬菜发酵的优良菌种,从果菜类蔬菜混合发酵样品中分离31株菌株,通过形态学初步筛选乳酸菌、酵母菌等,应用分子生物学方法(细菌16S rRNA和真菌ITS序列分析)进行鉴定,评估菌株的生长能力、产酸能力、耐受性(耐盐、耐酸、耐亚硝酸盐)和亚硝酸盐降解能力,利用熵值法对菌株性能进行综合评价,并对发酵蔬菜样品进行感官评分。结果表明筛选出链格孢菌(L1)、阿根廷乳酸杆菌(L4)、乳酸杆菌(L5)、短乳杆菌(L8)和假酵母菌(L10)5株菌,能显著提高发酵蔬菜的感官品质;其中,L4菌株在生长速度、产酸能力、耐盐性以及亚硝酸盐降解能力方面表现较好,发酵24 h的OD_(600)值达到1.9,pH值达到3.84,最高可耐受10%的盐浓度,亚硝酸盐降解率为97.87%。熵值法综合评价结果显示,菌株L4具有最优发酵性能,是一株理想的蔬菜发酵菌,可用于生产低亚硝酸盐含量且风味优良的发酵蔬菜产品。该研究为丰富蔬菜发酵菌菌种资源及菌株的进一步开发与利用奠定了基础。

基于一阶差分光谱的海水硝酸盐氮与亚硝酸盐氮测量方法

硝酸盐氮与亚硝酸盐氮是海洋水质监测的重点参数,也是研究海洋氮循环的重要参考。紫外吸收光谱法操作简单,响应快速,适用于多种水质参数监测,但测量中硝酸盐氮与亚硝酸盐氮存在混叠干扰以及海水离子干扰。提出了一种硝酸盐氮与亚硝酸盐氮快速测量方法,对光谱进行一阶差分等预处理,使用相关系数搜索进行波段优化,使用BP神经网络进行浓度反演,模型的预测值与真实值线性相关系数为0.998。与国外同类设备进行了比对测试,两者线性相关系数为0.982。参加了烟台市海洋环境监测预报中心2023年夏季航次,进行了应用测试,与实验室方法进行了比对分析,两者线性相关系数为0.902,说明本方法能够实现海水硝酸盐氮与亚硝酸盐氮的快速测量,为后续原位监测仪器的研制提供参考。

组分可调的PdRh双金属纳米酶用于亚硝酸盐精准高效比色传感

采用无模板一锅水热法,通过调控钯(Pd)与铑(Rh)摩尔比,制备了系列PdRh双金属纳米酶(Pd_(3)Rh,PdRh和PdRh_(3)),并研究了其类过氧化物酶(POD-like)及类氧化酶(OXD-like)活性.结果表明,双金属纳米酶的催化活性比单金属纳米酶(Pd和Rh)更高,且表现出明显的组分依赖性.其中,PdRh_(3)和PdRh分别表现出最强的POD-like和OXD-like活性.酶促动力学分析表明,PdRh_(3)纳米酶以3,3',5,5'-四甲基联苯胺(TMB)和H_(2)O_(2)为底物的米氏常数(K_(m))分别为15.65和381.99μmol/L,对应的最大反应速率(v_(max))分别为8.40×10^(-8)和11.01×10^(-8) mol/(L·s).此外,PdRh_(3)纳米酶的POD-like活性表现出pH依赖性,在pH=5时活性最佳.在此条件下,开发了基于PdRh_(3)纳米酶的比色传感体系,根据445和652 nm处吸光度比值(A_(445nm)/A_(652nm))与亚硝酸根离子(NO_(2)^(-))浓度的线性关系,实现了对溶液中亚硝酸盐浓度的快速定量检测.结果表明,在pH=5的缓冲溶液和纯水中,该体系检出限分别为0.467和30.523μmol/L,且在多种盐离子干扰下特异性良好,在生物传感中具有较大应用潜力.

亚硝酸盐氧化细菌研究进展与展望

亚硝酸盐氧化细菌(Nitrite Oxidizing Bacteria,NOB)是全球氮循环过程中的关键微生物,主要功能是将亚硝酸盐氧化为硝酸盐。近十年来基于现代分子生态技术的发展,NOB的研究取得了很大的进展,主要包括:NOB的碳氮代谢途径及多样性远远超过以往的认知,如NOB不仅可以氧化亚硝酸盐,也可以氧化尿素、氨以及氰酸盐获取能量;丰富了NOB与环境因素的响应及生态位分化特征的研究,其中Nitrospira更偏好于低氧的贫营养环境,中温的富营养环境更有利于Nitrobacter的生存;对NOB Nitrospira与全程氨氧化细菌(Complete Ammonia Oxidizer,comammox Nitrospira)之间的联系与差异进行了初步探索,二者虽然同属于Nitrospira谱系并且都具备亚硝酸盐氧化能力,但comammox Nitrospira对亚硝酸盐的亲和力较低而对氨具有较高的亲和力,主要分布在低氨的寡营养生境,而NOB Nitrospira对亚硝酸盐有较高亲和力,主要分布在低亚硝酸盐环境。本文基于上述最新研究进展进行了介绍与总结,并对该领域今后的研究进行了展望:在今后的研究中土壤环境或许可以成为NOB研究的新切入点;迫切需要探究缩短NOB分离和培养的方法并结合分子生态技术揭示NOB代谢多样性的实际依据以及NOB在碳氮循环中的真正贡献;探究NOB在代谢和生物化学方面的新机制,为揭示和预测NOB在环境中的响应提供理论支持。

食品亚硝酸盐电化学传感器研发

借助于简单可控的电化学技术,依次将电化学还原氧化石墨烯(ERGO)和铂纳米颗粒(PtNPs)修饰到石墨糊电极(GPE)表面,制得PtNPs/ERGO/GPE。电化学表征结果显示,PtNPs/ERGO/GPE对亚硝酸盐(NO_(2)^(-))的电化学氧化具有显著催化作用,在最佳检测条件下,NO_(2)^(-)在PtNPs/ERGO/GPE上的氧化峰电流与其浓度在7.0×10^(-6)~4.0×10^(-3) mol/L范围内呈良好线性关系,检出限低至2.0×10^(-6) mol/L(S/N=3)。此外,PtNPs/ERGO/GPE用于NO_(2)^(-)检测还具有良好的特异性、稳定性和重现性,且可用于食品样品中NO_(2)^(-)含量的准确、快速检测。PtNPs/ERGO/GPE制备简单、性能好且成本低,可用作一次性食品亚硝酸盐电化学传感器件,具有良好的应用前景。

Fe-N-C单原子催化剂电催化亚硝酸盐制氨

[目的]为进一步拓展单原子催化剂在亚硝酸盐还原制氨领域的应用,提出了一种铁-氮-碳(Fe-N-C)单原子催化剂电催化亚硝酸盐还原制氨的新体系.[方法]以二氧化硅为硬模板,2,6-二氨基吡啶为碳氮前驱体,硝酸铁为金属盐,通过“热解-刻蚀”策略制备了Fe-N-C单原子催化剂,并将其应用于亚硝酸盐制氨反应.[结果]多种结构表征结果显示,Fe-N-C催化剂表面的Fe物种呈现高度分散特征并以单原子形式存在.此外,Fe物种的化学环境主要是+2和+3价混合态,且通过与4个吡啶氮配位而稳定存在,即Fe-N-C催化剂的金属中心微观配位环境为Fe-N4结构.与纯氮碳(N-C)载体相比,本研究制备的Fe-N-C催化剂具有优异的亚硝酸盐还原性能,不仅表现出更高的起始还原电位(0 V vs可逆氢电极),具有接近100%的产氨法拉第效率和高的氨产率[8.4 mg/(h·cm^(2))],并且在连续20次催化循环测试中显示出优异的催化稳定性.[结论]本研究制备的Fe-N-C单原子催化剂对亚硝酸盐还原制氨具有优异的电催化活性,其高活性可能来源于对NO_(2)-的显著吸附,并进一步促进活性氢参与脱氧加氢过程.该Fe-N-C单原子催化亚硝酸盐还原体系可为后续合成氨的活性中心设计提供指导方向.

生物炭强化硫自养反硝化过程中亚硝酸盐的积累

硫自养反硝化(SADN)可为厌氧氨氧化(Anammox)提供亚硝酸盐(NO_(2)^(-)-N).为了促进SADN过程的NO_(2)^(-)-N积累,本实验以S^(0)为电子供体,考察了污泥-煤矸石基生物炭(SCBC)对SADN中NO_(2)^(-)-N积累率及抗冲击能力的影响.实验结果表明,投加SCBC使SADN的NO_(3)^(-)-N还原速率由70.6 mg·L^(-1)·h^(-1)提升至107.7 mg·L^(-1)·h^(-1),NO_(2)^(-)-N还原速率由30.5 mg·L^(-1)·h^(-1)提升至35.1 mg·L^(-1)·h^(-1),这使得NO_(2)^(-)-N积累率由48.2%提升至63.0%.当遇到冲击负荷(300 mg·L^(-1)的NO_(3)^(-)-N)时,SADN的还原性能下降,6 d后逐步恢复并继续提高,不投加则需12 d才能恢复.投加SCBC 60 d后,PN/PS和PN值分别为3.51和5.27 mg·g^(-1),高于不投加的2.36和3.44 mg·g^(-1).高通量测序均能检测到反硝化菌Thiobacillus、Sulfurimonas和Thermomonas,投加SCBC对反硝化菌起到富集作用,使其占比分别由40.0%、0.61%、0.03%上升为51.8%、2.71%、3.47%.总之,添加SCBC为提高SADN的NO_(2)^(-)-N积累提供了一个新方法,这也为污泥和煤矸石的资源化利用提供了一种新的途径.

四川泡菜发酵早期亚硝酸盐生成转化途径的初探

为研究四川泡菜发酵早期亚硝酸盐生成转化机制,测定了白萝卜泡菜发酵前5 d总酸、亚硝酸盐含量,并进行宏基因组学分析。研究发现,泡菜浸渍液总酸由发酵初始(0.03±0.00)g/100 g迅速上升到5 d的(0.74±0.04)g/100 g,亚硝酸盐含量在发酵1 d达到峰值(20.681 mg/L),随后逐渐降至低水平。发酵起始时,体系内以假单胞菌属(Pseudomonas)等杂菌为主,1 d后肠杆菌属(Enterobacter)成为优势微生物,随后乳植物杆菌属(Lactiplantibacillus)增加并占主导。固氮酶(1.18.6.1)、同化硝基氮还原酶(1.7.1.1/1.7.7.2)、异化硝基氮还原酶(1.7.5.1)、亚硝基氮还原酶(1.7.1.15)等亚硝酸盐代谢酶基因在泡菜发酵早期丰度较高。乳植物杆菌属与总酸呈显著正相关,与亚硝酸盐含量呈现负相关,亚硝酸盐代谢相关酶基因与大部分杂菌呈正相关。泡菜中杂菌可能通过1.7.1.1、1.7.7.2、1.7.5.1生成亚硝酸盐,并通过1.7.1.15将其还原为胺,产酸可能是乳酸菌清除亚硝酸盐的主要途径。

振动辅助排痰配合乙酰半胱氨酸雾化吸入治疗婴幼儿肺炎的临床效果

目的观察振动辅助排痰配合乙酰半胱氨酸雾化吸入治疗婴幼儿肺炎的临床效果。方法选取2021年8月—2022年8月萍乡市妇幼保健院儿内一科收治的肺炎患儿80例,采用随机数字表法分为观察组和对照组,各40例。2组患儿均予常规治疗,对照组在常规治疗基础上加用吸入用乙酰半胱氨酸溶液治疗,观察组在对照组基础上配合振动辅助排痰,2组患儿均治疗7 d。比较2组临床效果、症状体征(发热、咳嗽、气喘、肺部湿性啰音)消失时间、住院时间、住院费用,治疗前后血常规指标[白细胞计数(WBC)、C反应蛋白(CRP)、降钙素原(PCT)]水平以及不良反应。结果观察组治疗总有效率为97.50%,高于对照组的85.00%(χ^(2)=3.914,P=0.048);观察组发热、咳嗽、气喘消失时间、肺部湿性啰音消失时间及住院时间均短于对照组,住院费用低于对照组(P<0.01);治疗7 d后,2组WBC及血清CRP、PCT水平均较治疗前下降,且观察组低于对照组(P<0.01);观察组与对照组不良反应总发生率(12.50%vs.10.00%)比较差异无统计学意义(χ^(2)=0.125,P=0.723)。结论振动辅助排痰配合乙酰半胱氨酸雾化吸入治疗婴幼儿肺炎的临床效果较好,可有效缓解患儿症状表现与炎性反应程度,且安全性较高。

Sandmeyer法合成2-溴-6-氯甲苯

采用Sandmeyer法以3-氯-2-甲基苯胺为原料,亚硝酸钠为重氮化试剂,在低温、酸性环境下得到重氮盐,再利用铜基催化剂、不同温度的条件下分解,得到2-氯-6-溴甲苯。适宜合成条件为:以30%硫酸溶解胺,以亚硝酸钠的硫酸溶液成盐,以氢溴酸为溴源、铜粉为催化剂、在0℃分解。其中,酸用量为原料的5倍,n(3-氯-2-甲基苯胺)∶n(亚硝酸钠)∶n(铜粉)∶n(工业氢溴酸)=1∶1.2∶0.1∶1.2,2-溴-6-氯甲苯的收率可达95%。