36 research outputs found
The genetic diversity of lactic acid producing bacteria in the equine gastrointestinal tract
No full textSeventy-two lactic acid producing bacterial isolates (excluding streptococci) were cultured from the gastrointestinal tract of six horses. Two of the horses were orally dosed with raftilose to induce lactic acidosis and laminitis while the remaining four were maintained on a roughage diet. Near complete 16S rDNA was amplified by PCR from the genomic DNA of each isolate. Following RFLP analysis with the restriction enzymes MboI, HhaI and HinfI, the PCR products from the 18 isolates that produced L- and/or D-lactate were subsequently cloned and sequenced. DNA sequence analysis indicated that the majority of the isolates were closely related to species within the genus Lactobacillus, including Lactobacillus salivarius, Lactobacillus mucosae and Lactobacillus delbrueckii. Four isolates were closely related to Mitsuokella jalaludinii. Lactic acid producing bacteria (LAB) from the equine gastrointestinal tract was dominated by representatives from the genus Lactobacillus, but also included D-lactate-producing bacteria closely related to M. jalaludinii. Identification and characterization of LAB from the equine gastrointestinal tract should contribute to our understanding and management of fermentative acidosis, ulceration of the stomach and laminitis.Rafat A.M. Al Jassim, Paul T. Scott, Andrea L. Trebbin, Darren Trott, Christopher C. Pollit
Cloud Statistics from Calipso Lidar Data for the Performance Assessment of a Methane Space Lidar
No full textIn this thesis a performance assessment for the future German-French climate monitoring initiative, Methane Remote Sensing Lidar Mission (MERLIN), proposed by DLR and CNES in 2010 was undertaken. A general space lidar performance issue is the obstruction by optically dense clouds. For this purpose cloud free statistics, the global cloud top flatness and global cloud top distributions were derived from the Cloud-Aerosol Lidar and Infrared Path�nder Satellite Observation (CALIPSO) level 2, 333 m and 5 km lidar cloud-layer products between 01 January 2007 and 01 January 2008. Merging both data sets together thereby allowed the best possible simulation of near global and seasonal real world atmospheric conditions that a spaceborne Integrated Path Differential Absorption (IPDA) lidar like MERLIN will encounter. With 40.5 % overall global cloud free fraction, a cloud gap distribution which is following a power-law distribution with exponent 1.51 +-� 0.01 together with a mean cloud gap length of 7.41 km and about 200 daily global cloud top flatness events, the analysis reveals a dominance of small cloud gaps which is confirmed by a low median cloud gap length of only 1 km. While the cloud free fraction results were compared and confirmed with Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) seasonal and annual cloud fraction data, the power-law distribution of cloud gaps was confirmed by an extensive statistical analysis using maximum likelihood estimation, Kolmogorov-Smirnov statistics and likelihood ratio tests. Taking 6.05 x 10e8 individual CALIPSO measurements of the year 2007 with a horizontal resolution of 333 m and computing cloud gap and cloud free statistics for 2 �x 2� latitude/longitude grid points thereby identified regional and seasonal changes in the probability of spaceborne lidar surface detection. The analysis reveals that MERLIN will be able to perform near global methane mixing ratio column retrievals
Time-Resolved Analysis of the Structural Dynamics of Assembling Gold Nanoparticles
No full textThe hydrophobic collapse is a structural transition of grafted polymer chains in a poor solvent. Although such a transition seems an intrinsic event during clustering of polymer-stabilized nanoparticles in the liquid phase, it has not been resolved in real time. In this work, we implemented a microfluidic 3D-flow-focusing mixing reactor equipped with real-time analytics, small-angle X-ray scattering (SAXS), and UV-vis-NIR spectroscopy to study the early stage of cluster formation for polystyrene-stabilized gold nanoparticles. The polymer shell dynamics obtained by in situ SAXS analysis and numerical simulation of the solvent composition allowed us to map the interaction energy between the particles at early state of solvent mixing, 30 ms behind the crossing point. We found that the rate of hydrophobic collapse depends on water concentration, ranging between 100 and 500 nm/s. Importantly, we confirmed that the polymer shell collapses prior to the commencement of clustering
Fabrication of Novel Microfluidic Devicesfor Investigating Ultrafast Structural Dynamics
No full textThe recent developments of several X-ray synchrotrons and (ultrabright) XFEL light sources with increasingly narrow and brilliant beams have allowed facilities to reduce both sample volume and data acquisition time. Moreover, this has created new opportunities for investigating versatile sample conditions while simultaneously increasing demands in terms of sample preparation. The microfluidic flat liquid jet based sample preparation techniques are emerging as promising alternatives for manipulating small sample volumes and which can be integrated more easily into the experimental X-ray setups. The main goal of the thesis is to study and develop an innovative microfluidic flat liquid jet device technology that is suitable for microfocus X-ray scattering techniques. Furthermore, simultaneously providing a platform to control the experimental conditions for investigating particle alignments, spinning fibers and spectroscopic studies in the future. The first part of the thesis deals with the development, fabrication and testing of high aspect ratio microfluidic flat liquid jet devices. The development of a method to fabricate three-dimensional and three-layered microstructures from photoresists SU-8 2050 was established with an increased nozzle height of 100 µm. Achieving exact control of the nozzle geometry at such high aspect ratios requires solving several issues such as edge beading, wafer bowing and UV-exposure artefacts. These issues have been overcome by successfully optimizing protocols and process parameters to produce high aspect ratio structures with suitable feature sizes. The optimized devices are based use the gas dynamic virtual nozzle (GDVN) principle, where the co-axially flowing gas focusses the liquids. The highly stable thin liquid sheets reported here enabled us to reduce the sample consumption up to tenfold in comparison to the traditional flat liquid jet injectors without gas -focusing. Our devices are produced by well-established soft-lithography techniques, which allow for exact control over the design and reproducibility of the nozzle geometry. The microfluidic flat liquid jet device generates a series of alternating, orthogonal stable liquid sheets with thicknesses approximately a few microns. Sheet width and length are dependent on the high aspect ratio nozzle geometry and flow parameters such as gas pressure and liquid flow rates. This work enriches multiple arenas such as soft X-ray spectroscopy because of optical the flatness and spatial stability of these jets. And hence offers exciting well-grounded versatile opportunities for ultrafast molecular science, ultrafast chemical dynamics, X-ray beam diagnostics and industrial applications. Furthermore, the optimized fabrication methodology and nozzle geometry parameters provide useful design directions for whipping and fiber jets. The second part of the thesis is a wide-angle X-ray scattering (WAXS) study of the influence of shear flow on the alignment of anisotropic nanoparticles in a liquid sheet. Spindle-shaped hematite nanoparticles showed alignment across and along the sheet jet with a preferred orientation along the flow axis in the center of the sheet and along the jet. Furthermore, the optimized GDVN geometry is also suitable for micro- and nano-fiber spinning from polymer solutions by offering very high jetting stability, relinquishing the need for external fiber pulling mechanisms. These nozzle geometries allow fiber production of nanocomposite fibers and nanofibers with various tunable morphologies such as round, flat and grooved. Compared to other fiber spinning methods, this technique is inexpensive, user-friendly and permits precise fiber diameter control (~250 nm to ~15 μm), high production rate (m/s-range) and direct fiber deposition without clogging. The fabricated hematite/CNT nanocomposite endless fibers have exciting applications in the future. These fibers have thermal and electrical conductivity, magnetic properties, enhanced mechanical stability and stimuli-responsive features
Framing smallholder inclusion in global value chains – case studies from India and West Africa
No full textA resurrected interest in agriculture has brought in its wake growing
interest in smallholders in the global South by scholars, companies,
governments and development agencies alike. While non-governmental
organisations and development agencies see the potential to reduce poverty,
companies look upon smallholder agriculture as a widely untapped resource
for the sourcing of crops and as a sales market for agricultural inputs. While
the important role of large corporate buyers of agricultural produce as lead
firms in value chains is often discussed and emphasised, the power of
providers of technology and agricultural inputs is being rather neglected.
In this paper, we analyse two case studies of technology and input providers
in agricultural value chains and their role in smallholder inclusion with
the aim of finding out how such companies impact the governance of the value
chains. To do so we combine insights from the value chain literature with
the concept of framing/overflowing
Sonchus palustris L.
No full textSonchus palustris L. Turkey A9 Erzurum: Oltu, Oltu’ya 8 km kala, Kaleboğazı köyü girişi, 1397 m, N 40 32, E 041 54, dere içi-kenarı, bataklık alanlar, 24 vii 2014. Güzel 262 & Gültepe (KTUB) (OK 048726, OK078622) Turkey A6 Tokat: Zile’den Pazar’a giderken, 574 m. N 40 20, E 035 51, Populus sp. altları, kurumuş sulak alanlar, 21 vii 2015. Güzel 413 & Makbul (KTUB) (OK 048725, OK078621) Turkey A8 Bayburt: Dikmetaş Köyü’nden Bayburt’a giderken, Populus sp. altları, sulama kanalı kenarı, 1450 m, 05 viii 2020. Güzel 975 & Gültepe (KTUB) Deutschland: Brandenburg, Teltow-Fläming (Kreis), Trebbin, Wandeweg S Blankensee, Wegrand, sumpfing, Feucht, 27.07.2003, Dürbye DÜR 2231 mit Rost, Meyer (B) Iran, W Azerbaijan occidentalis, prope Habashi Bala N Qotur, 1950 m ad rivum, 18.07.1974, K. H. Rechinger 49632 (B) Iran, Regio transcaspica, Aschabad, Suluklü (Saratowka) ad fines Persiae, ad rivulos et in pratis humidis, 31.07.1900, J . Bornmüller 954 (B)Published as part of Güzel, Murat Erdem, 2022, A new subgenus of Sonchus (Asteraceae: Cichorieae) inferred from molecular data, pp. 211-229 in Phytotaxa 531 (3) on page 228, DOI: 10.11646/phytotaxa.531.3.3, http://zenodo.org/record/588618
Supplementary Material for: Interplay between the Conserved Pore Residues Thr-91 and His-209 Controls Formate Translocation through the FocA Channel
No full textThe formate channel A (FocA) belongs to the formate-nitrite transporter (FNT) family, members of which permeate small monovalent anions. FocA from Escherichia coli translocates formate/formic acid bi-directionally across the cytoplasmic membrane during fermentative growth. Two residues are particularly well conserved within the translocation pores of FNTs: threonine-91 and histidine-209, based on E. coli FocA numbering. These residues are located at the tips of two broken transmembrane helices and control anion passage. H209 is the only charged residue within the pore and interacts with T91. Here, we addressed the role of the T91-H209 interaction network in the permeation of formate in vivo through FocA by performing an extensive amino acid-exchange study. Monitoring changes in intracellular formate using a formate-responsive fdhFP::lacZ reporter system revealed that T91 is essential for the ability of FocA to translocate formate bi-directionally. Only exchange for serine was partially tolerated, indicating that the hydroxyl group of T91 is mechanistically important. Substitution of H209 with N or Q was previously shown to convert FocA into a formate efflux channel. We show here that residue-exchanges A, I and T at this position resulted in a similar phenotype. Moreover, efflux function was confirmed for these FocA variants by measuring excreted formate in the culture medium. Substitution of bulky or charged residues for H209 prevented bi-directional formate passage. Studies using hypophosphite, a toxic analogue of formate taken up by FocA, and which causes impaired growth, confirmed that T91 and H209 substitutions essentially abolished, or drastically reduced, FocA´s translocation activity, as shown by reduction of growth rate. The exceptions were T91S- and T91Y-exchange variants that retained partial ability to take up inhibitory hypophosphite. Together, our findings indicate that T91 is essential for formate permeation in both directions; however, it is particularly important to allow anion efflux. Moreover, H209 is essential for formate uptake by FocA, strongly suggesting that protonation-deprotonation of this residue plays a role in formate uptake. Finally, our results substantiate the premise that efflux and influx of formate by FocA are mechanistically distinct processes that are controlled by the interplay between T91 and H209
Effective role of CaO/P2O5 ratio on SiO2-CaO-P2O5 glass system
No full textIn the present work, the effect of the CaO/P2O5 ratio on the composition of sol-gel synthesized 58SiO2-(19 − x)P2O5–(23 + x)CaO (x = 0, 5, 10 and 15 mol%) glass samples was studied. Further, the effect of NBO/BO ratio on hydroxy carbonated apatite layer (HCA) forming ability based on dissolution behavior in simulated body fluid (SBF) solution was also investigated. CaO/P2O5 ratios of synthesized glass samples were 1.2, 2, 3.6, and 9.5, respectively. NBO/BO ratios were obtained using Raman spectroscopic analysis as 0.58, 1.20, 1.46, and 1.78, respectively. All samples were soaked in the SBF solution for 7 days. The calculated weight losses of these samples were 58%, 64%, 83%, and 89% for corresponding NBO/BO ratios. The increase in CaO/P2O5 ratio increases the NBO/BO ratios. However, the increase in NBO/BO ratio increases HCA forming ability of SBF treated samples. The HCA crystalline layer formation was confirmed through X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Raman and Infrared spectroscopic analysis. Higher CaO/P2O5 ratio favors the increase in HCA formation for SBF treated calcium phospho silicate glasses
