Bacillus subtilis
is a widely distributed aerobic Gram-positive species of bacteria. As a tool in the lab, it has the advantages of nonpathogenicity and limited likelihood of becoming drug resistant. ...It is a probiotic strain that can be directly used in humans and animals. It can be induced to produce spores under nutrient deficiency or other adverse conditions.
B. subtilis
spores have unique physical, chemical, and biochemical characteristics. Expression of heterologous antigens or proteins on the surface of
B. subtilis
spores has been successfully performed for over a decade. As an update and supplement to previously published research, this paper reviews the latest research on spore surface display technology using
B. subtilis
. We have mainly focused on the regulation of spore coat protein expression, display and application of exogenous proteins, and identification of developing research areas of spore surface display technology.
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CEKLJ, DOBA, EMUNI, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Diterpene synthase VenA is responsible for assembling venezuelaene A with a unique 5-5-6-7 tetracyclic skeleton from geranylgeranyl pyrophosphate. VenA also demonstrates substrate promiscuity by ...accepting geranyl pyrophosphate and farnesyl pyrophosphate as alternative substrates. Herein, we report the crystal structures of VenA in both apo form and holo form in complex with a trinuclear magnesium cluster and pyrophosphate group. Functional and structural investigations on the atypical
DSFVSD
motif of VenA, versus the canonical Asp-rich motif of DDXX(X)D/E, reveal that the absent second Asp of canonical motif is functionally replaced by Ser116 and Gln83, together with bioinformatics analysis identifying a hidden subclass of type I microbial terpene synthases. Further structural analysis, multiscale computational simulations, and structure-directed mutagenesis provide significant mechanistic insights into the substrate selectivity and catalytic promiscuity of VenA. Finally, VenA is semi-rationally engineered into a sesterterpene synthase to recognize the larger substrate geranylfarnesyl pyrophosphate.
2,5-Furandicarboxylic acid (FDCA) is attracting increasing attention because of its potential applications as a sustainable substitute to petroleum-derived terephthalic acid for the production of ...bio-based polymers, such as poly(ethylene 2,5-furandicarboxylate) (PEF). Many catalytic methods have been developed for the synthesis of FDCA, including chemocatalysis, biocatalysis, photocatalysis, and electrocatalysis. Biocatalysis is a promising approach with advantages that include mild reaction condition, lower cost, higher selectivity, and environment amity. However, the biocatalytic production of FDCA has hardly been reviewed. To fully understand the current research developments, this review comprehensively considers the research progress on toxic effects and biodegradation of furan aldehydes, and then summarizes the latest achievements concerning the synthesis of FDCA from 5-hydroxymethylfurfural and other chemicals, such as 2-furoic acid and 5-methoxymethylfurfural. Our primary focus is on biocatalytic methods, including enzymatic catalysis (in vitro) and whole-cell catalysis (in vivo). Furthermore, future research directions and general developmental trends for more efficient biocatalytic production of FDCA are also proposed.
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CEKLJ, DOBA, EMUNI, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, a novel NO electrochemical microsensor, which is fabricated by modifying the surface of a carbon fiber microdisk electrode (CFMDE, diameter: 5–7
μm) with single-walled carbon nanotubes ...(SWNTs) and Nafion membrane, is reported for the first time. The modification of SWNTs dramatically improves the sensitivity of CFMDEs, and the detection limit for NO is 4.3
nM that is nearly 10 times lower than that from the bare one and lower than most NO electrochemical sensors reported before. The Nafion membrane offers a good barrier to some interferents such as nitrite and ascorbic acid without losing response speed to NO. The sensor has been successfully applied to the measurement of NO release from single isolated human umbilical vein endothelial cells (HUVECs). Real-time amperometric data show that the addition of
l-arginine (
l-arg) or acetylcholine (ACh) can cause a quick increase in NO production with a maximum concentration of 232
±
44
nM (
n
=
5) and 159
±
29
nM (
n
=
5), respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Chitosan/glycerophosphate thermosensitive hydrogel crosslinked physically was a potential drug delivery carrier; however, long gelation time limits its application. Here, chitosan-amino acid (AA) ...thermosensitive hydrogels were prepared from chitosan (CS), αβ-glycerophosphate (GP), and
l
-lysine (Lys) or
l
-glutamic acid (Glu). The prepared CS-Lys/GP and CS-Glu/GP hydrogel showed good thermosensitivity and could form gels in a short time. The optimal parameters of CS-Lys/GP hydrogel were that the concentration of CS-Lys was 2.5%, the ratio of CS/Lys was 3.5/1.0, the ratio of CS-Lys/GP was 4.5/1.0. The optimal parameters of CS-Glu/GP hydrogel were that the concentration of CS-Glu was 3.0%, the ratio of CS/Glu was 2.0/1.0, and the ratio of CS-Glu/GP was 4.0/1.5. Chitosan-amino acid (CS-AA) thermosensitive hydrogel had a three-dimensional network structure. The addition of model drug tinidazole (TNZ) had no obvious effect on the structure of hydrogel. The results of infrared spectroscopy showed that there were hydrogen bonds between amino acids and chitosan. In vitro release results showed that CS-Lys/GP and CS-Glu/GP thermosensitive hydrogels had sustained release effects. Thus, the chitosan-amino acid thermosensitive hydrogels hold great potential as a sustained release drug delivery system.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
The sweeping camera systems in the surveying and mapping industry are usually efficient in image acquisition, for the photography coverage of a single strip is relatively large. The ...triangulation angle of correspondence is overly tiny to adopt traditional block adjustment (BA). This study analysed the imaging principle of the Chinese APS7K comprehensive camera system and proposed an aerial triangulation method for the data this system acquired. The proposed method first determines the adjacent matrix from the POS data and trajectory information. The other part of the method is to overcome the weak relative geometry in a single strip by introducing the digital elevation model (DEM) data into the block adjustment scheme. The optimal solution of adjustment is obtained by iteratively solving the problem. We verified the optimisation's effectiveness by checking stitched orthophoto and check points from Google Earth. The results show that mosaic discrepancy is eliminated, the reprojection error is reduced to subpixel level, and positioning accuracy is better than 0.4 meter (ground sample distance is 0.2 meter) after adjustment with ground control points. Finally, the method’s shortcomings and prospects are summarized
.
Résumé
Les systèmes de caméra à balayage utilisés dans l'industrie de la topographie et de la cartographie sont souvent efficaces pour l'acquisition d'images, car la couverture photographique d'une seule bande est relativement grande. L'angle de correspondance de la triangulation est trop petit pour permettre un traditionnel ajustement par blocs. Cette étude a analysé le principe d´acquisition de la caméra chinoise APS7K et a proposé une méthode de triangulation aérienne pour les données acquises par ce système. La méthode proposée détermine d'abord la matrice d´adjacence à partir des données POS et des informations sur la trajectoire. L'autre partie de la méthode consiste à surmonter les limites de la géométrie relative d´une seule bande en introduisant les données du modèle numérique d'élévation (MNE) dans l'ajustement par blocs. La solution optimale de l'ajustement est obtenue en résolvant le problème de manière itérative. Nous avons vérifié l'efficacité de l'optimisation en contrôlant un assemblage d´orthophotos avec des points de contrôle de Google Earth. Les résultats montrent que le décalage de la mosaïque est éliminée, que l'erreur de reprojection est réduite à un niveau sub‐pixel et que la précision du positionnement est meilleure que 0,4 mètre (la distance d'échantillonnage au sol est de 0,2 mètre) après l'ajustement avec les points de contrôle au sol. Enfin, les insuffisances de la méthode et les perspectives sont résumées.
Zusammenfassung
Die Schwenkkamerasysteme in der Vermessungs‐ und Kartierungsindustrie sind normalerweise effizient in der Bilderfassung, da die fotografische Abdeckung eines einzelnen Streifens relativ groß ist. Der Triangulationswinkel der Entsprechung ist zu klein, um die traditionelle Blockausgleichung (BA) zu übernehmen. Diese Studie analysierte das Bildgebungsprinzip des chinesischen umfassenden Kamerasystems APS7K und schlug eine Aerotriangulationsmethode für die Daten vor, die dieses System erfasste. Die vorgeschlagene Methode bestimmt zunächst die Adjazenzmatrix aus den POS‐Daten und Trajektorieninformationen. Der andere Teil der Methode besteht darin, die schwache relative Geometrie in einem einzelnen Streifen zu überwinden, indem die Daten des digitalen Höhenmodells (DEM) in das Blockausgleichungsschema eingeführt werden. Die optimale Ausgleichungslösung wird durch iteratives Lösen des Problems erhalten. Wir haben die Effektivität der Optimierung überprüft, indem wir gesteppte Orthofotos und Prüfpunkte von Google Earth überprüft haben. Die Ergebnisse zeigen, dass die Mosaikdiskrepanz eliminiert wird, der Reprojektionsfehler auf Subpixelebene reduziert wird und die Positionierungsgenauigkeit nach der Ausgleichung mit Bodenpasspunkten besser als 0,4 Meter ist (Bodenauflösung beträgt 0,2 Meter). Abschließend werden die Schwächen und Perspektiven der Methode zusammengefasst.
Resumen
Las cámaras con sistema de barrido en la industria topográfica y cartográfica suelen adquirir imágenes con eficiencia, ya que la cobertura fotográfica de una sola tira de imágenes es relativamente grande. El ángulo de triangulación de puntos correspondientes es demasiado pequeño para adoptar el ajuste de bloque (BA) convencional. En este estudio se analiza el principio de captación de imagen de la cámara china APS7K y se propone un método de triangulación aérea para los datos adquiridos por este sistema. El método propuesto primero determina la matriz de adyacencias a partir de los datos de POS y la información de trayectoria. La otra parte del método es introducir restricciones del modelo de elevación digital (DEM) en el ajuste de bloques para contrarrestar la débil relación geométrica entre imágenes de una tira. La solución óptima de ajuste se obtiene iterativamente. Verificamos la eficacia de la optimización comprobando en mosaico de ortofotoimágen y los puntos de control de Google Earth. Los resultados muestran que se elimina la discrepancia del mosaico, el error de reproyección se reduce al nivel de subpíxel y la precisión de posicionamiento es mejor que 0,4 metros (el tamaño de píxel es de 0,2 metros) después del ajuste con los puntos de control del suelo. Finalmente, se resumen las deficiencias y perspectivas del método.
摘要
摆扫成像系统的航带覆盖面积较大，在测绘中应用中具有很高的影像采集效率。但由于摆扫影像同名点的交会角小、交会条件弱，不适合采用传统区域网平差方法进行处理。本文以中国APS7K摆扫相机系统为研究对象，分析了其成像原理后，提出了对APS7K摆扫相机数据进行空中三角测量处理的方法。该方法首先根据POS数据和影像轨迹信息确定邻接矩阵，之后，为克服单航带交会弱问题引入数字高程模型(DEM)并应用到区域网平差中，通过迭代求最优解。为验证本方法的有效性，使用多航带正射影像拼接以及谷歌地球数据对比进行检查。结果表明，该方法可将重投影误差减小到亚像素，完全消除了正射拼接的不一致性，在有控制点情况下，绝对误差优于0.4米(地面元大小0.2米)。文章最后总结了该方法的不足之处，并对未来研究进行了展望。
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
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