Continuous countercurrent salting-out extraction of 1,3-propanediol from fermentation broth in a packed column

The possibility of continuous extraction of 1,3-propanediol in a experimental packed column was investigated using a salting-out extraction system of dipotassium phosphate/ethanol. Mass transfer of 1,3-propanediol takes place from the dispersed phase (salt-rich solution) to the continuous phase (ethanol). The influences of flow rate of dispersed phase and size of packing material on partition coefficient and recovery of 1,3-propanediol were investigated and the results were compared with those obtained in spray column and test tube. Furthermore, the influences of various system compositions on hold up of dispersed phase, mass transfer coefficient, and system stability were also studied in the column packed by stainless steel Dixon 3 × 3 mm. It was found that the packed column showed a good extraction efficiency and stability. Besides, 1,3-propanediol recovery of 90.30% was obtained during a 11 h continuous operation when the real fermentation broth was used. At the same time, 94.4% of phosphate could be recovered when 0.2 volume of anhydrous ethanol was added into the raffinate phase at pH 4.0.     

Analytical FcRn affinity chromatography for functional characterization of monoclonal antibodies

The neonatal Fc receptor (FcRn) is important for the metabolic fate of IgG antibodies in vivo. Analysis of the interaction between FcRn and IgG in vitro might provide insight into the structural and functional integrity of therapeutic IgG that may affect pharmacokinetics (PK) in vivo. We developed a standardized pH gradient FcRn affinity liquid chromatography method with conditions closely resembling the physiological mechanism of interaction between IgG and FcRn. This method allows the separation of molecular IgG isoforms, degradation products and engineered molecules based on their affinity to FcRn. Human FcRn was immobilized on the column and a linear pH gradient from pH 5.5 to 8.8 was applied. FcRn chromatography was used in comparison to surface plasmon resonance to characterize different monoclonal IgG preparations, e.g., oxidized or aggregated species. Wild-type and engineered IgGs were compared in vitro by FcRn chromatography and in vivo by PK studies in huFcRn transgenic mice. Analytical FcRn chromatography allows differentiation of IgG samples and variants by peak pattern and retention time profile. The method can distinguish: 1) IgGs with different Fabs, 2) oxidized from native IgG, 3) aggregates from monomer and 4) antibodies with mutations in the Fc part from wild-type IgGs. Changes in the FcRn chromatographic behavior of mutant IgGs relative to the wild-type IgG correlate to changes in the PK profile in the FcRn transgenic mice. These results demonstrate that FcRn affinity chromatography is a useful new method for the assessment of IgG integrity.     

New osteological and morphological data of four species of Aphaniops (Teleostei; Aphaniidae)

Aphaniops dispar, widespread around the Arabian Peninsula, was recently separated in four species (A. dispar, A. hormuzensis, A. kruppi, A. stoliczkanus) by molecular results and colour patterns, but the morphological differences are small and call for more studies. Here we report differences in skeleton and median fin osteology of these species. In addition, we introduce the term 'modified caudal vertebra' to describe caudal vertebrae that are not directly associated with caudal ray support but are visibly modified from a 'usual' caudal vertebra. Aphaniops hormuzensis, an endemic species to southern Iran, has a significantly higher number of modified caudal vertebrae compared to the more widespread A. stoliczkanus and A. dispar, and also to A. kruppi. This is a surprising result as the caudal skeleton and related structures of the posterior caudal vertebral column have yielded successful results in separating between families or genera, but there are only a few studies that have examined these structures for their role in species diagnosis. Our study also highlights that state-of-the-art methods in X-raying and improved staining procedures assist in the discrimination of superficially similar species.     

马里亚纳海沟可培养水生细菌的多样性

【目的】马里亚纳海沟是地球表面最深的海沟,环境极端多样,如高压、低温及无光,拥有独特的微生物资源。本研究旨在探究马里亚纳海沟不同深度水生细菌形态特征并挖掘可培养细菌资源。【方法】采集马里亚纳海沟7个层位海水(2–8727 m),利用原子力显微镜与扫描电镜观察水生微生物的形态特征;采用2种常规培养基(1/5×2216E和1/30×2216E)及6种选择性培养基(有机碳氮组合),结合切向流与高压富集培养进行水生细菌分离与鉴定。【结果】从不同深度水样中发现多种大小不一的细菌类群(130 nm–1.5μm),以球菌和杆菌为主。在表层水体中常见颗粒附着的细菌,在深层水体中常见自由游动的细菌。共鉴定365株可培养水生细菌,隶属于3个门、31个属与56个种。γ-变形菌纲(Gammaproteobacteria)是绝对优势类群(占据可培养细菌总数的62.7%),相对丰度在深层水体中高于浅层。交替单胞菌属(Alteromonas,21.8%)和亚硫酸杆菌属(Sulfitobacter,19.1%)是主要优势属,在浅层水体中占绝对优势。稀释的2216E与氨基酸培养基对海杆菌属的选择性更好,葡萄糖-甘露糖培养基与牛磺酸-乙醇酸培养基对稀有细菌的选择性更好。7株菌(5种)是潜在的新型细菌。此外,通过切向流富集培养与压力筛选培养分别分离得到70株(22属)可通过0.22-μm细菌(0.22-μm-passable bacteria)与33株(8属)耐压细菌。【结论】马里亚纳海沟不同深度水样中不同营养利用型细菌、可通过0.22-μm细菌与耐压细菌及其形态均具有丰富的多样性。本研究所获得的不同类型的细菌菌株为研究细菌在马里亚纳海沟中生物地球化学功能及其营养类型差异和高压适应机制奠定了菌株基础。     

Quantum chemical insight on vibration spectra of silica systems

A set of silicate ions and corresponding lithium salts have been quantum chemically (QC) simulated in a “free molecule” approach. The infrared (IR), inelastic neutron scattering (INS), and Raman spectra have been simulated and fitted to the experimentally registered ones. The complete assignment of the vibrational bands along with the intensities and potential energy distribution has been performed. The applicability of the traditionally used quasimolecule Si–O–Si model to the interpretation of bands near 440–480 cm^? 1 and so-called “Boson” peak near 50 cm^? 1 has been critically discussed.     

c-fos Expression in Gracilothalamic Tract Neurons after Electrical Stimulation of the Injured Sciatic Nerve in the Adult Rat

The number of c-fos protein-like immunoreactive (Fos-LI) cells in the gracile nucleus was determined after electrical stimulation at Aα/Aβ-fiber strength of the normal and of the previously injured sciatic nerve in adult rats. No Fos-LI cells were seen after electrical stimulation of the noninjured sciatic nerve, or after sciatic nerve injury without electrical stimulation. However, stimulation 21 days after sciatic nerve transection resulted in numerous Fos-LI cells in the ipsilateral gracile nucleus. Combined Fos immunocytochemistry and retrograde labeling from the thalamus showed that the majority (76%; range = 70–80%) of the cells in the gracile nucleus that expressed Fos-LI after nerve injury projected to the thalamus. The results indicate that morphological, biochemical, and physiological alterations in primary sensory central endings and second-order neurons, which have earlier been demonstrated in the dorsal column nuclei after peripheral nerve injury, are accompanied by changes in the c-fos gene activation pattern after stimulation of the injured sciatic nerve. A substantial number of the c-fos-expressing neurons project to the thalamus.     

Dependence of Subjective Traverse Length on Velocity of Moving Tactile Stimuli

Two series of experiments were performed to assess the effects of stimulus velocity on human subjects' perception of the distance traversed by a moving tactile stimulus. In all experiments, constant-velocity stimuli were applied to the dorsal surface of the left forearm; velocities ranging between 1.0 and 256 cm/sec were used. In some experiments the stimuli moved from distal to proximal over the skin, and in others they moved from proximal to distal. The length of skin contacted by the moving stimulus was defined by a plate having an aperture of 4.0 × 0.5 cm.

In the first series of experiments, subjects were required to compare the distance traversed by a test stimulus delivered 2 sec after a standard stimulus, and also to report the on-locus and the off-locus of the brushing stimulus. In the second series of experiments, the subjects rated the perceived distance on the skin using a free-magnitude-estimation procedure. The data from both series of experiments defined the same relationship between stimulus velocity and perceived stimulus distance. More specifically, although the length of skin contacted by the stimulus was the same at all velocities, subjects' estimates of stimulus distance decreased with increasing stimulus velocity. In addition, the function relating estimates of stimulus distance to velocity was flat for velocities between 5 and 20 cm/sec, but possessed an appreciable negative slope at lower and higher velocities.

It is interesting that the plateau of the relationship between perceived stimulus distance and velocity occurred within the range of velocities that human subjects employ to scan textured surfaces; it also corresponded precisely with the range of stimulus velocities at which the directional sensitivity of somatosensory cortical neurons and human subjects is optimal.     

Community Structure of Archaea in the Water Column above Gas Hydrates in the Gulf of Mexico

Microorganisms play fundamental roles in the ecosystem of the Gulf of Mexico (GOM), yet their vertical distributions along the depth continuum of water column are not well known. In this study, we presented the 16S rDNA sequences and lipid profiles in the context of water chemistry to characterize the archaeal community structure above a gas hydrate mound (MC 118) in GOM. Our results showed that all archaeal sequences were related to unknown species of Crenarchaeota or Euryarchaeota. Phylogenetically, group II –β Euryarchaeota dominated the surface water and mid-depth (400-m) water (74% and 58% of total archaeal species, respectively) whereas the marine group I-γ Crenarchaeota dominated the bottom (869 m) water (61% of total archaeal species). Estimates of the Shannon index showed the highest diversity of planktonic Archaea at the 400 m depth. Glycerol dialkyl glycerol tetraether (GDGT) lipids were detected from the 400- and 869-m depths only and characterized by relatively high abundances of GDGT-5 (crenarchaeol) and GDGT-0. Our studies suggested a possible zonation of archaeal community in the water column, which did not seem to be affected by the possible venting of hydrocarbons from the hydrate location in GOM.     

Column Bioleaching of Low-Grade Chalcopyritic Ore Using Moderate Thermophile Bacteria

Bacterially assisted heap leaching is an economical technology for treating low grade copper sulphides. In the present research, bioleaching of low grade chalcopyrite ore (1% chalcopyrite, and 3% pyrite) have been investigated using moderate thermophilic bacteria. The ore sample has low solubility in acid solution (about 5%). Experiments were carried out using column reactors and the effect of particle size (?12.7, ?19.07 and ?25.04 mm) and external addition of carbon dioxide to the induced air (10% v/v) have been investigated. Results have shown that the copper recovery increased with reducing particle size, and carbon dioxide addition improved bacterial activity and copper dissolution. In the optimum condition, i.e., particles finer than 12.07 mm and 10% (v/v) carbon dioxide addition, 69.68% of copper were extracted.