生物酶和微生物技术改善烟叶香气的研究进展

生物酶和微生物在烟叶醇化发酵过程中发挥着重要作用。目前,利用生物酶和微生物技术提高烟叶品质、改善烟叶香气,已成为烟草行业关注的热点。利用酶制剂处理烟叶可以降解烟叶的蛋白质、果胶、纤维素等生物大分子,以达到提高烟叶品质和改善烟叶香气的作用。利用微生物对烟叶进行发酵可以有效调整和改善烟叶内部化学组分的比例,增加烟叶中的香气物质。综述了生物酶和微生物技术在烟叶产香发酵中的研究进展及其在烟叶发酵机理及增香技术中的应用,重点阐述了微生物和生物酶提高烟叶香气、改善烟叶品质以及降解烟叶中蛋白质、淀粉、果胶、纤维素等大分子物质的研究现状,分析了目前微生物和生物酶在实际应用中存在的问题,以期为今后使用生物酶和微生物技术改善烟叶香气提供理论依据。     

烟叶微生物及其在烟叶发酵和醇化中的作用研究进展

微生物在烟叶发酵和醇化过程中具有十分重要的作用。本文综述了烟叶微生物概况及其在烟叶发酵和醇化中的应用和研究进展。主要介绍了烟叶微生物的区系划分、烟叶发酵和醇化过程中微生物动态变化以及外源添加微生物的应用方法。阐述了微生物在缩短烟叶发酵和醇化周期、改善烟叶品质、降低烟叶有害物质和提高烟叶安全性等方面的研究应用成果。最后,对该领域今后的研究方向提出了展望。     

微生物改善烟叶品质研究进展

从微生物缩短烟叶发酵时间、降低烟叶有害成分、增加烟叶香气等方面概述了微生物在改善烟叶品质方面的研究进展,并对其在烟叶上的应用前景作了分析。     

烟叶主要生物酶活性变化规律及其在烟叶发酵中的应用

烟叶中的生物酶在烟叶的生长及发酵过程中起着重要作用.他们能够促进烟叶内部有机物质的分解与转化,调整烟叶中各种化学成分的比例,提高烟叶中香气成分的形成和积累,从而提高烟叶的综合品质.综述了烟叶生长、加工过程中淀粉酶、蛋白酶、多酚氧化酶的活性变化规律,以及外加生物酶在烟叶发酵中的应用现状.     

烟叶采收成熟度对烘烤过程中酶促棕色化反应相关指标的影响

以烤烟新品种‘豫烟11号’为试验材料,研究未熟、成熟和过熟烟叶在常规三段式烘烤过程中水分含量、多酚氧化酶(PPO)活性和多酚类物质含量的变化特征,以及指标间的关系,以明确烟叶采收成熟度对酶促棕色化反应的影响及各指标之间的内在联系。结果表明:(1)在烘烤过程中,3个成熟度烟叶的水分含量逐渐降低;其PPO活性先缓慢下降,再快速上升,最后急剧下降;而总酚与绿原酸含量先缓慢上升,再缓慢下降,最后快速上升。未熟和过熟烟叶的芸香苷含量变化与总酚类似,成熟烟叶芸香苷含量呈现缓慢‘降-升-降-升’趋势;3个成熟度烟叶莨菪亭含量变化总体呈波动上升趋势。(2)在酶促棕色化反应敏感期(烘烤48~66h),水分含量和PPO活性以未熟烟叶最高,成熟烟叶居中,过熟烟叶最低,总酚和绿原酸含量以成熟烟叶最高,过熟烟叶略低,而未熟烟叶最低;3个成熟度烟叶芸香苷和莨菪亭含量差异没有明显规律性。(3)在棕色化反应敏感期,不同成熟度烟叶PPO活性变化与多酚类物质积累速度均呈负相关关系,未熟与成熟烟烟叶分别达到了极显著和显著水平,而与过熟烟叶没有达到显著水平,未熟、成熟烟叶因过高的PPO活性明显降低了多酚类物质积累速度,而过熟烟叶因较低的PPO活性对多酚类物质的积累速度影响较小。研究认为,适当提高烟叶田间采收成熟度,能够有效地提高烘烤过程中烟叶的失水速率,降低PPO活性,有利于防止烟叶发生褐变,提高烤后烟叶的外观和内在品质。     

烤烟发酵有益细菌的分离筛选及优良菌株的鉴定

已有研究表明,利用从烟叶表面分离得到的微生物对烟叶进行发酵,可以改善烟叶的品质,在烟草生产中具有重要的应用潜力.本研究采用平板画线法,从烟叶、茶叶和笋干上分离得到细菌38株,并将这些菌株应用于烟叶发酵,根据烟叶化学成分和感官评吸对细菌处理的效果进行评价.结果发现,从烟叶上分离到的YX3、YX11和YX12等10个菌株可提高烟叶品质.对其中一个优良菌株(YX37)进行分子鉴定,结果表明其属于芽苞杆菌属.本研究结果证明了从烟叶表面分离烟叶发酵有益细菌的可行性和有效性,为细菌在烟草生产上的应用打下基础.     

烟叶表面微生物及其应用*

利用微生物发酵技术改善烟叶品质,是目前国内外学争相研究的课题。在发酵过程中有微生物、酶及化学物质的协同作用,诱发一系列与香气物质变化有关的生化反应。其中微生物贯穿烟叶发酵始终,对烟叶品质起重要作用。人为的将微生物用于烟叶发酵是提高烟叶品质、改善烟气特性的新途径,给予烟叶自然、醇和芳香,减少苦涩气味,改善余味。基于以上目的,中综括烟叶微生物种类及应用概况,试图将微生物资源广泛应用于烟叶发酵,诱发烟叶内与香气物质转化有关的生化代谢途径,达到改善烟叶品质和增进烟叶香气目的。     

谷氨酰胺合成酶抑制剂对烤烟烘烤特性的影响

以烤烟品种‘K326’叶片为材料,在达到工艺成熟期前7d分别用质量分数为0.005%和0.01%的谷氨酰胺合成酶(GS)抑制剂4-[羟基(甲基)膦酰基]-D/L-高丙氨酸(草铵膦)溶液喷施烤烟叶片,研究了烟叶烘烤过程中烘烤特性的变化特征。结果表明:于烟叶工艺成熟期前7d喷施GS抑制剂,能够显著降低烘烤过程中烟叶的叶绿素、类胡萝卜素含量和多酚氧化酶(PPO)活性;增加烟叶失水速率和丙二醛(MDA)含量,显著提高烟叶烘烤后黄烟比例,并降低杂色烟比例。研究认为,在烟叶工艺成熟期前7d喷施GS抑制剂,可增强烟叶的易烤性和耐烤性,使烟叶更容易变黄,并同时减少棕色化反应的发生,但高浓度的GS抑制剂使烟叶失水速率过快,不利于烟叶定色,烘烤后青烟比例升高,对烟叶外观质量形成不利。     

真菌菌剂改善烟叶品质的初步研究*

利用分离自不同生境烟叶上的7个真菌菌株菌剂处理上部叶烤烟烟丝,分析表明,处理后烟叶内与品质相关的主要化学成分含量发生了改变,烟叶品质得到改善。其中菌株BF03、BF06及BF63使烟叶内糖、氮、烟碱、蛋白质等主要化学成分含量及各种成分之间比例趋于平衡。评吸结果表明,经供试菌剂处理的烟叶香气质提高,香气量增加,刺激性减小,余味舒适,烟叶品质明显高于对照。     

烟草调制期间微生物研究进展

烟草调制期间,烟叶上的微生物对烟叶产品质量具有重要影响.从微生物的主要类群、变化动态、对烟叶品质的影响及其控制利用等方面进行了阐述.     

大兴安岭林区针叶林的生长方程及火灾林木死亡率

本文用随机模拟的方法建立了北方针叶林的生长方程及其受到火灾侵害后的林木死亡率,定量地研究了火灾对这种林分变动的影响．     

非线性自食种群动力系统的稳定性

本文讨论了一类主要由昆虫自食引起的非线性种群动态模型的稳定性．首先给出确定性模型,并着重讨论其一个特殊情形．通过在参数空间中辨识稳定域的边界,可以相对直观地分析种群动态．对于随机模型,是利用在确定性模型中加入对数尺度下的正态随机项形成的,该模型具有较好的统计性质,便于将现实的非线性时间序列数据引进系统中来．     

Nerve growth factor induces cell cycle arrest of astrocytes

Neurotrophins can influence multiple cellular functions depending on the cellular context and the specific receptors they interact with. These neurotrophic factors have been extensively studied for their ability to support neuronal survival via Trk receptors and to induce apoptosis via the p75(NTR). However, the p75(NTR) is also detected on cell populations that do not undergo apoptosis in response to neurotrophins. In particular, the authors have detected p75(NTR) expression on astrocytes during development and after seizure-induced injury. In this study, the authors investigated the role of Nerve growth factor (NGF) in regulating astrocyte proliferation and in influencing specific aspects of the cell cycle. The authors have demonstrated that NGF prevents the induction of cyclins and their association with specific cyclin-dependent kinases, and thereby prevents progression through the G1 phase of the cell cycle. Since the authors have previously shown that p75(NTR) but not TrkA, is expressed in astrocytes, these data suggest that activation of p75(NTR) promotes withdrawal of astrocytes from the cell cycle, which may have important consequences during development and after injury.     

Effects of phototherapy with blue light on chromosomes from human lymphocytes

The dangerous effects of phototherapy have been matter of discussion in recent years. In order to evaluate its in vitro action on the human DNA, the authors have performed the karyotypic analysis on 20 cultures of lymphocytes. In different times 16 cultures have been exposed to the action of a "blue light" fluorescent lamp, commonly used for the treatment of neonatal jaundice. The authors have not evidenced any morphological or numerical change of the karyotype in any of the cultures.     

The distribution of Rh blood groups in the population of Puglia

The authors have conducted a study on the genic frequency within the Rh system in 3.000 subjects of certain Apulia ancestry. The results, in agreement with those of previous authors, have demonstrated that the frequency of the haplotypes containing "d" appears clearly lower than the national average value.     

Network-Driven Reputation in Online Scientific Communities

The ever-increasing quantity and complexity of scientific production have made it difficult for researchers to keep track of advances in their own fields. This, together with growing popularity of online scientific communities, calls for the development of effective information filtering tools. We propose here an algorithm which simultaneously computes reputation of users and fitness of papers in a bipartite network representing an online scientific community. Evaluation on artificially-generated data and real data from the Econophysics Forum is used to determine the method''s best-performing variants. We show that when the input data is extended to a multilayer network including users, papers and authors and the algorithm is correspondingly modified, the resulting performance improves on multiple levels. In particular, top papers have higher citation count and top authors have higher h-index than top papers and top authors chosen by other algorithms. We finally show that our algorithm is robust against persistent authors (spammers) which makes the method readily applicable to the existing online scientific communities.     

Conflict of Interest Disclosures for Clinical Practice Guidelines in the National Guideline Clearinghouse

Background

Conflict of interest (COI) is an important potential source of bias in the development of clinical practice guidelines (CPGs) and high rates of COI among guideline authors have been reported in the past. Our objective was to report current rates of disclosure and specific author COI across a broad range of CPGs and to examine whether CPG characteristics were associated with the presence of disclosures and of conflicts.

Methods and Findings

We selected a random sample of 250 CPGs listed in the National Guideline Clearinghouse on November 22, 2010, representing approximately a 10% sample of guidelines listed in the NGC on that date. We abstracted information on author COI from each CPG and examined predictors of the disclosures and COI using a logistic generalized estimating equation regression model. 87% of organizations developing guidelines had a CPG-specific policy, however, 40% of CPGs did not indicate that they had collected disclosures from guideline authors. In addition, 42% of organizations that did collect author disclosures did not have those disclosures available in the public domain. Of CPGs where we had disclosures for all authors, 60% had one or more authors with a conflict. On average, 28% of the authors of CPGs with available disclosures had a COI. Guidelines that were published in journals with an impact factor greater than 5.0 were more likely to have one or more authors with a COI than guidelines not published in journals.

Conclusions

Rates of disclosure of author COI and the public availability of that information are unacceptably low, however rates of COI among guideline authors may have decreased in recent years. Continued efforts are needed to establish and enforce optimal COI policies in clinical practice guideline development in order to minimize the risk of bias associated with those conflicts.     

Psychological sequelae of failed scalp replantation

Published reports of avulsed scalp replant attempts have been promising. Numerous case reports and published series have demonstrated a greater than 90 percent replantation success rate. However, there exists a paucity of articles on the management of patients following failed scalp replantation attempts. The authors recognize numerous stressors that affect these patients, including the inciting traumatic event, hospitalizations, multiple surgical interventions, postsurgical therapies, and disfigurement caused by non-hair-bearing scalp. Thus, as part of the medical management for scalp replant patients, one must address the psychological factors surrounding the medical management. Over the past 25 years, the authors have experienced four cases of scalp replant failures, each posing an opportunity to examine the postoperative course of these patients. Symptoms ranging from mild anxiety to depressive symptoms have been observed in all of these patients. In fact, patient symptoms often satisfied the criteria for major depressive disorder or posttraumatic stress disorder. The authors recognize the importance of informing patients and their families of the immediate and potential long-term complications following an unsuccessful scalp replant attempt. The authors advise that all patients be provided immediate psychiatric evaluation and, if necessary, counseling and medication therapy, regardless of scalp replantation outcome.     

Retraction

These articles have been retracted at the request of the authors.Reason: In July of 2002, Mechanisms of Development started publishing its section Gene Expression Patterns (until then included under the Mechanisms of Development title) under the separate title Gene Expression Patterns, as a separate section of Mechanisms of Development.This change was clearly communicated at the time in the journal and on the journal’s web site. The Editors also informed the authors about this. Early 2003, it came to our attention that a mistake was made during the split with regard to a number of Gene Expression Patterns articles in the pipeline (between initial submission and final acceptance). Due to a miscommunication for which the publisher accepts the responsibility, not all the editors used the same cut-off date for the split. As a result, some articles have been published under the Gene Expression Patterns title that should have been published in the main section of Mechanisms of Development. The publisher is very much aware of the serious nature of this mistake and we apologise to the authors, readers and editors of the journal.In the first months of 2003, we consulted with a number of the authors involved to discuss possible options to remedy the situation, and at the request of the authors, we agreed to retract the articles of the authors concerned, who requested this. We also agreed to offer this opportunity to those authors who were notified by the editors, but who misunderstood the message due to the fact that the proofs of their article still had the MoD logo and title on the opening page. The articles are re-published in supplement 1 to Vol. 119 under the Mechanisms of Development title.The Publisher     

Mindestanforderungen an die artgerechte Haltung von Krokodilen in privaten Terrarien und zoologischen Einrichtungen, 2. Teil - Artentabellen

Based on the theoretical facts of the previously released text version of the minimum requirements for the keeping of crocodiles, the authors now publish in addition a list with specific data for practical use. This list allows a quick overview of the most important details that should be considered while keeping crocodiles. The authors have compiled specific details for every known species of crocodiles.