Integration of biocatalyst and process engineering for sustainable and efficient n‐butanol production

Recent environmental economic developments generate a need for sustainable and cost‐effective (microbial) processes for the production of high‐volume, low‐priced bulk chemicals. As an example, n‐butanol has, as a second‐generation biofuel, beneficial characteristics compared to ethanol in liquid transportation fuel applications. The industrial revival of the classic n‐butanol (ABE) fermentation requires process and strain engineering solutions for overcoming the main process limitations: product toxicity and low space–time yield. Reaction intensification on the biocatalyst, fermentation, and bioprocess level can be based on economic and ecologic evaluations using quantifiable constraints. This review describes the means of process intensification for biotechnological processes. A quantitative approach is then used for the comparison of the massive literature on n‐butanol fermentation. A comprehensive literature study—including key fermentation performance parameters—is presented and the results are visualized using the window of operation methodology. The comparison allowed the identification of the key constraints, high cell densities, high strain stability, high specific production rate, cheap in situ product removal, high n‐butanol tolerance, to operate in situ product removal efficiently, and cheap carbon source. It can thus be used as a guideline for the bioengineer during the combined biocatalyst, fermentation, and bioprocess development and intensification.     

Low dissipation computing in biological systems

Biological systems frequently need to solve many computationally hard decision and optimization problems. The solution of these problems by digital computers as presently understood requires exponentially large energy dissipation. This severely restricts the ability of digital computers to attack such problems. We shall show that only polynomial dissipation is required to solve these problems adequately by "physical annealing", as realized in the genetic system, making these problems tractable energetically.     

暂时性脑缺血诱导c-fos原癌基因和鸟氨酸脱羧酶基因表达

应用大鼠椎动脉与颈内动脉结扎造成暂时性脑缺血再灌注以及RNA点杂交方法观察c-fos基因与鸟氨酸脱羧酶(ODC)基因表达的动力学过程。结果表明:大鼠大脑皮质c-fos基因在再灌后0.5至3小时表达,ODC基因在6小时至14小时表达;海马的c-fos基因则自36至72小时呈现高水平表达,ODC基因表达与之相对同步或稍延后。但是暂时性脑缺血却不能诱导c-Myc基因表达。上述结果提示c-fos及ODC可能在缺血型脑损伤后具有特殊作用。文中对缺蛋再灌引起cfos-及ODC基因表达的机制进行了分析与讨论,并提出“神经元应激状态”这一概念以描述神经元对伤害性刺激的反应历程。     

Seasonal effects on the freerunning rhythm of circadian activity of longnose dace (Rhinichthys cataractae)

Synopsis Freerunning circadian rhythms of locomotor activity in individual longnose dace sampled from a population at 41°N latitude were recorded under constant darkness throughout the year. There was an annual cycle in the length of the circadian period, with maximum and minimum lengths of mean period of 23.6 and 21.6 h recorded during summer (June) and winter (December), respectively. These annual changes in period length may have resulted from seasonal changes in entrainment by natural light-dark cycles and their after-effects on endogenous circadian rhythms. The possibility of an endogenous circannual rhythm was also considered.     

结直肠漏评分联合中性粒细胞与淋巴细胞比值、C反应蛋白与白蛋白比值对直肠癌Dixon术后吻合口漏的预测价值研究

摘要 目的：研究结直肠漏评分（CLS）联合中性粒细胞与淋巴细胞比值（NLR）、C反应蛋白与白蛋白比值（CAR）对直肠癌低位前切除（Dixon）术后吻合口漏的预测价值。方法：选取2020年4月-2022年3月于贵州医科大学附属医院行直肠癌Dixon手术的260例患者,根据术后吻合口漏发生情况分为吻合口漏组与无吻合口漏组。收集患者临床资料,术后评估两组CLS评分,术后第1、3 d检测中性粒细胞、淋巴细胞计数、C反应蛋白和白蛋白,计算NLR、CAR;采用Logistics回归分析术后吻合口漏的影响因素,采用受试者工作特征（ROC）曲线分析CLS、NLR、CAR对吻合口漏的预测价值。结果：260例患者术后发生20例吻合口漏,发生率为7.69%。吻合口漏组CLS评分高于无吻合口漏组（P＜0.05）;术后第1 d两组NLR、CAR比较差异无统计学意义（P＞0.05）,术后第3 d吻合口漏组NLR、CAR高于无吻合口漏组（P＜0.05）。两组吻合口至肛缘距离、糖尿病史、术前低蛋白血症、术前肠梗阻占比比较差异有统计学意义（P＜0.05）。多因素Logistics回归分析显示,吻合口距肛缘距离、糖尿病史、术前低蛋白血症、术前肠梗阻、CLS、NLR、CAR是患者术后发生吻合口漏的影响因素（P＜0.05）。ROC曲线分析显示,CLS的曲线下面积（AUC）为0.851,NLR的AUC为0.861,CAR的AUC为0.859,三者联合的AUC为0.945,高于单独检测。结论：Dixon术后发生吻合口漏患者CLS评分、NLR和CAR升高,CLS评分联合NLR、CAR可有效预测直肠癌Dixon术后吻合口漏发生风险,可作为评估吻合口漏的辅助指标,以降低术后吻合口漏的发生率。     

Quantification of power consumption and oxygen transfer characteristics of a stirred miniature bioreactor for predictive fermentation scale-up

Miniature parallel bioreactors are becoming increasingly important as tools to facilitate rapid bioprocess design. Once the most promising strain and culture conditions have been identified a suitable scale-up basis needs to be established in order that the cell growth rates and product yields achieved in small scale optimization studies are maintained at larger scales. Recently we have reported on the design of a miniature stirred bioreactor system capable of parallel operation [Gill et al. (2008); Biochem Eng J 39:164-176]. In order to enable the predictive scale-up of miniature bioreactor results the current study describes a more detailed investigation of the bioreactor mixing and oxygen mass transfer characteristics and the creation of predictive engineering correlations useful for scale-up studies. A Power number of 3.5 for the miniature turbine impeller was first established based on experimental ungassed power consumption measurements. The variation of the measured gassed to ungassed power ratio, P(g)/P(ug), was then shown to be adequately predicted by existing correlations proposed by Cui et al. [Cui et al. (1996); Chem Eng Sci 51:2631-2636] and Mockel et al. [Mockel et al. (1990); Acta Biotechnol 10:215-224]. A correlation relating the measured oxygen mass transfer coefficient, k(L)a, to the gassed power per unit volume and superficial gas velocity was also established for the miniature bioreactor. Based on these correlations a series of scale-up studies at matched k(L)a (0.06-0.11 s(-1)) and P(g)/V (657-2,960 W m(-3)) were performed for the batch growth of Escherichia coli TOP10 pQR239 using glycerol as a carbon source. Constant k(L)a was shown to be the most reliable basis for predictive scale-up of miniature bioreactor results to conventional laboratory scale. This gave good agreement in both cell growth and oxygen utilization kinetics over the range of k(L)a values investigated. The work described here thus gives further insight into the performance of the miniature bioreactor design and will aid its use as a tool for rapid fermentation process development.     

骨科下肢大手术后深静脉血栓形成的预防及护理

目的:探讨骨科下肢大手术后深静脉血栓形成的预防及护理措施。方法:对98例骨科下肢大手术患者,术前做好高危患者的评估及健康宣教,并指导患者术前进行适应性功能锻炼,同时做好心理护理。术后详细了解术中情况,保持引流通畅,保护下肢静脉,做好基本预防和机械预防,密切观察有无DVT或PTE表现。结果:94例患者顺利康复,有效率达95.9%;只有3例并发DVT,1例并发PTE,经治疗均顺利康复。结论:通过科学的预防和护理,骨科下肢大手术患者深静脉血栓的并发率大为减少。     

Experimental charge density from electron microscopic maps

The charge density (CD) distribution of an atom is the difference per unit volume between the positive charge of its nucleus and the distribution of the negative charges carried by the electrons that are associated with it. The CDs of the atoms in macromolecules are responsible for their electrostatic potential (ESP) distributions, which can now be visualized using cryo‐electron microscopy at high resolution. CD maps can be recovered from experimental ESP density maps using the negative Laplacian operation. CD maps are easier to interpret than ESP maps because they are less sensitive to long‐range electrostatic effects. An ESP‐to‐CD conversion involves multiplication of amplitudes of structure factors as Fourier transforms of these maps in reciprocal space by 1/d², where d is the resolution of reflections. In principle, it should be possible to determine the charges carried by the individual atoms in macromolecules by comparing experimental CD maps with experimental ESP maps.     

胸外科患者术后医院感染的病原菌与危险因素分析

目的:分析胸外科患者术后医院感染的病原菌分布及危险因素,为防控医院感染提供数据支持。方法:选择2014年1月至2015年5月医院接受胸外科手术治疗的患者284例进行研究。回顾性分析284例患者的临床病历数据资料以及细菌培养与鉴定的结果,分析医院感染的主要部位及病原菌分布,以及产生医院感染的危险因素。结果:284例患者共有82例发生医院感染,感染率是28.87%,感染部位以呼吸系统为主,占56.10%;检出病原菌88株,革兰阴性菌71株,占80.68%,以铜绿假单胞菌为主,占30.68%。革兰阳性菌17株,占19.32%,以金葡菌为主,占9.09%。单因素分析发现,胸外科术后医院感染与年龄、手术时间、住院时间及糖尿病史有关,差异有统计学意义(P0.05);Logistic回归分析显示,年龄≥60岁、手术时间2 h、住院时间15 d以及有糖尿病史是胸外科术后医院感染的危险因素。结论:胸外科患者术后医院感染的病原菌分布以铜绿假单胞菌与金葡菌为主,应重点防范影响感染的危险因素,以降低感染率。     

香蕉果实冻干过程参数优化的研究

对香蕉果实冻干生产工艺中的物料厚度、冻结方法、加热板温度、干燥室真空度等参数进行比较试验,结果表明,各过程参数对香蕉冻干品质量和产量均有显著的影响。香蕉冻干过程中参数较佳的工艺条件建议为物料厚度选取5~7 mm,采用速冻方法冻结,加热板温度设定45℃,干燥室真空度控制于20~30 Pa。