Filter Pore Size Research Articles

Patterns of bacterial diversity in the marine planktonic particulate matter continuum.

Depending on their relationship with the pelagic particulate matter, planktonic prokaryotes have traditionally been classified into two types of communities: free-living (FL) or attached (ATT) to particles, and are generally separated using only one pore-size filter in a differential filtration. Nonetheless, particulate matter in the oceans appears in a continuum of sizes. Here we separated this continuum into six discrete size-fractions, from 0.2 to 200 μm, and described the prokaryotes associated to each of them. Each size-fraction presented different bacterial communities, with a range of 23-42% of unique (OTUs) in each size-fraction, supporting the idea that they contained distinct types of particles. An increase in richness was observed from the smallest to the largest size-fractions, suggesting that increasingly larger particles contributed new niches. Our results show that a multiple size-fractionation provides a more exhaustive description of the bacterial diversity and community structure than the use of only one filter. In addition, and based on our results, we propose an alternative to the dichotomy of FL or ATT lifestyles, in which we differentiate the taxonomic groups with preference for the smaller fractions, those that do not show preferences for small or large fractions, and those that preferentially appear in larger fractions.

Effects of various chemical cleaning conditions for pressured MF process.

A pilot-scale pressured hollow-fiber microfiltration (MF) process as pretreatment for the reverse osmosis process was studied and operated under various conditions to assess the relative influence of backwashing, chemical enhanced backwashing (CEB), and bag filter application. The pilot plant process consisted of backwashing but without the CEB or the bag filter as the first step of the research. As the second step of the research, the impact of the backwashing on permeability recovery was assessed at different intervals followed by the influence of CEB on flowrate recovery. Results from operating the pilot-scale hollow-fiber membrane modules for more than 1 year have demonstrated that the appropriate pore size of bag filters was 25-50 μm and the optimized backwashing process was every 30 minutes with 25 mg/L of NaOCl, and CEB with an interval of 10 cycles with the use of 100 mg/L NaOCl.

Filtration of washed erythrocytes in atherosclerosis and diabetes mellitus

A positive-pressure filtration technique, using 5 µm pore-size Nuclepore filters, was used to study erythrocyte deformability in 47 atherosclerotic patients (compared with 25 controls) and 55 diabetics (compared with 37 controls). The effects of hyperproteinaemia, which caused significant increases in plasma viscosity and whole-blood viscosity in the atherosclerotic patients, and which can also impair erythrocyte filtration, were eliminated by washing the erythrocytes. The leucocytosis of diabetes mellitus, which can also impair erythrocyte filtration, was corrected for by adjusting the filtration results to a standard leucocyte count of 7.5 × 109/l. After elimination of these extrinsic variables, the filterability of atherosclerotic and diabetic erythrocytes, from out-patients in the steady state, was not significantly different from that of control erythrocytes.

Rare earth element behavior during groundwater–seawater mixing along the Kona Coast of Hawaii

Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previous investigations showed that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45μm and 0.02μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries. Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more “pristine” groundwater from a well constructed in a lava tube at Kiholo Bay, were conducted with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student t-test, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows light REE (LREE)>middle REE (MREE)>heavy REE (HREE). Release of REEs in the mixing experiments is driven by decreases in the free metal ion activity in solution and the concomitant increase in the amount of each REE that occurs in solution as dicarbonato complexes [i.e., Ln(CO3)2−] as pH increases across the salinity gradient. Input-normalized REE patterns of Kona Coast groundwater and coastal seawater are nearly identical and relatively flat compared to North Pacific seawater, indicating that SGD is the chief source of these trace elements to the ocean along the Kona Coast. Additionally, REE concentrations of the coastal seawater are between 10 and 50 times higher than previously reported open-ocean seawater values from the North Pacific, further demonstrating the importance of SGD fluxes of REEs to these coastal waters. Taken together, these observations indicate that large-scale removal of REEs, which characterizes the behavior of REEs in the low salinity reaches of many surface estuaries, is not a feature of the subterranean estuary along the Kona Coast. A large positive gadolinium (Gd) anomaly characterizes groundwater from the vicinity of the WWTF. The positive Gd anomaly can be traced to the coastal ocean, providing further evidence of the impact of SGD on the coastal waters. Estimates of the SGD fluxes of the REEs to the coastal ocean along the Kona Coast (i.e., 1.3–2.6mmolNdday−1) are similar to recent estimates of SGD fluxes of REEs along Florida’s east coast and to Rhode Island Sound, all of which points to the importance of SGD as significant flux of REEs to the coastal ocean.

Concentration of radiocaesium in rice and irrigation water, and soil management practices in Oguni, Date, Fukushima.

The concentration of radiocaesium ((134) Cs and (137) Cs) in brown rice collected from Oguni, Date, Fukushima in 2011 was over 500 Bq kg(-1) , which was the provisional regulation value in 2011, and rice cultivation was prohibited in 2012. Rice culture was resumed following the application of K fertilizer as a countermeasure in 2013. The concentration of (137) Cs in soils and irrigation water in 2013 was in the range of 1200 to 4000 Bq kg(-1) (n = 31) and 0.078 to 1.1 Bq L(-1) (n = 7), respectively. The concentration of (137) Cs in the dissolved fraction in irrigation water filtered with 0.45 µm pore-size membrane filter was a relatively constant at 0.019 to 0.038 Bq L(-1) (n = 7). The concentration of (137) Cs in brown rice cultivated in the paddy fields after implementing the countermeasure was 1.1 to 24 Bq kg(-1) dry weight (n = 29), which was lower than the Standard Limits (100 Bq kg(-1) ). However, the concentration of Cs in rice cultivated under a similar agricultural management as in 2011 and prior to the Tokyo Electric Power Company Holdings' (TEPCO) Fukushima accident was over the Standard Limits. Integr Environ Assess Manag 2016;12:659-661. © 2016 SETAC.

High Seeding Density Induces Local Hypoxia and Triggers a Proinflammatory Response in Isolated Human Islets.

Hypoxia is the main threat to morphological and functional integrity of isolated pancreatic islets. Lack of oxygen seems to be of particular importance for functionality of encapsulated islets. The present study was initiated as an experimental model for the environment experienced by human islets in a confined space present during culture, shipment, and in an implanted macrodevice. Quadruplicate aliquots of isolated human islets (n = 12) were cultured for 24 h at 37°C under normoxic conditions using 24-well plates equipped with 8-µm pore size filter inserts and filled with islet aliquots adjusted to obtain a seeding density of 75, 150, 300, or 600 IEQ/cm(2). After culture viability, glucose-stimulated insulin release, DNA content as well as Bax and Bcl-2 gene expression were measured. Culture supernatants were collected to determine production of VEGF and MCP-1. Viability correlated inversely with IEQ seeding density (r = -0.71, p < 0.001), while the correlation of VEGF and MCP-1 secretion with seeding density was positive (r = 0.78, p < 0.001; r = 0.54, p < 0.001). Decreased viability corresponded with a significant increase in the Bax/Bcl-2 mRNA ratio at 300 and 600 IEQ/cm(2) and with a sigificantly reduced glucose-stimulated insulin secretion and insulin content compared to 75 or 150 IEQ/cm(2) (p < 0.01). The present study demonstrates that the seeding density is inversely correlated with islet viability and in vitro function. This is associated with a significant increase in VEGF and MCP-1 release suggesting a hypoxic and proinflammatory islet microenvironment.

Isolation of two diatom species with aquaculture potential (Bacillariophyceae) from the Pacific of Costa Rica

Due to the importance of primary production in the trophic network, most aquatic ecosystems rely on microalgae. However, there are fewer studies on phytoplankton in the Central American region, specifically on marine diatoms, in part because it is difficult to isolate and cultivate local species in tropical climates. The objective of this study is the isolation of two local diatoms of Chaetoceros and Nitzschia, potential food for aquatic organisms. Water samples was taken from the Nicoya Gulf, located in the Central Pacific coast of Costa Rica. The samples were successively filtered first through a 35µm pore size filter and then through one of 20µm. They were repeatedly isolated using modified Pasteur pipettes, and serial dilutions were done until a monoalgal culture was obtained. Two Bacillariophyceae were isolated: NGN1, genus Nitzschia; and CGN2, genus Chaetoceros. This study is a step toward reducing the importation of phytoplankton on feeding aquatic organisms by providing technical and scientific information to develop a microalgal culture from this region.

Preparation of [68Ga]PSMA-11 for PET–CT imaging using a manual synthesis module and organic matrix based 68Ge/68Ga generator

Introduction[68Ga]PSMA-11 is a relatively recently introduced radiopharmaceutical for PET–CT imaging of prostate cancer patients. The availability of 68Ge/68Ga generator and PSMA-11 ligand from commercial sources is facilitating the production of the radiopharmaceutical in-house. This paper describes our experience on the preparation of ~200 batches of [68Ga]PSMA-11 for conducting PET–CT imaging in patients suspected/suffering from prostate cancer. MethodsThe radiosynthesis of [68Ga]PSMA-11 was done in a hospital based nuclear medicine department using 68Ge/68Ga generator and a manual synthesis module, both supplied by Isotope Technologies Garching (ITG), Germany. The production involved the reaction of 5μg (5.3nmol) of PSMA-11 ligand in 1 ml of 0.25M sodium acetate buffer with 4ml of 68GaCl3 in 0.05M HCl for 5min at 105°C; followed by purification in a C18 cartridge and collection through a 0.22μm pore size filter. ResultsThe radiochemical yields obtained were consistently high, 93.19%±3.76%, and there was hardly any batch failure. The radiochemical purity of the product was >99% and the product was stable for over 2h; however it was used in patients immediately after preparation. About 200 batches of [68Ga]PSMA-11 were prepared during the period and more than 300 patients received the tracer during the 14months of study. No adverse reaction was observed in any of the patients and the image qualities were consistent with literature reports. Conclusion[68Ga]PSMA-11 with high radiochemical and radionuclidic purity is conveniently prepared by using a 68Ge/68Ga generator and manual synthesis module. The radiochemical yields are very high; and activity sufficient for 3–4 patients can be prepared in a single batch; multiple batches can be done on the same day and when needed after a gap of 1.5–2h.

Fish mouths as engineering structures for vortical cross-step filtration.

Suspension-feeding fishes such as goldfish and whale sharks retain prey without clogging their oral filters, whereas clogging is a major expense in industrial crossflow filtration of beer, dairy foods and biotechnology products. Fishes' abilities to retain particles that are smaller than the pore size of the gill-raker filter, including extraction of particles despite large holes in the filter, also remain unexplained. Here we show that unexplored combinations of engineering structures (backward-facing steps forming d-type ribs on the porous surface of a cone) cause fluid dynamic phenomena distinct from current biological and industrial filter operations. This vortical cross-step filtration model prevents clogging and explains the transport of tiny concentrated particles to the oesophagus using a hydrodynamic tongue. Mass transfer caused by vortices along d-type ribs in crossflow is applicable to filter-feeding duck beak lamellae and whale baleen plates, as well as the fluid mechanics of ventilation at fish gill filaments.

Laser damage dependence on the size and concentration of precursor defects in KDP crystals: view through differently sized filter pores.

We investigate the laser-induced damage performance at 1064 nm of potassium dihydrogen phosphate (KDP) crystals grown using filters of different pore sizes. The aim is to explore a novel method for understanding laser-matter interactions with regard to physical parameters affecting the ability of damage precursors to initiate damage. By reducing the pore size of filters in continuous filtration growth, we can improve laser damage resistance. Furthermore, we develop a model based on a Gaussian distribution of precursor thresholds and heat transfer to obtain a size distribution of the precursor defects. Smaller size and/or lower concentration of precursor defects could lead to better damage resistance.

Molecular gut content analysis demonstrates that Calanus grazing on Phaeocystis pouchetii and Skeletonema marinoi is sensitive to bloom phase but not prey density

The seawater samples were stained with primuline (Direct Yellow 59, Sigma-Aldrich Co), fixed with a solution containing 3.6% (v/v) glutaraldehyde and 10% (v/v) glycerol (final concentrations), and gently filtered onto black-stained 25 mm diameter 0.4-µm pore-size Nucleopore filters. Filters were mounted on slides and analyzed by epifluorescence microscopy. The method is a modification from Grebecki (1962), Hobbie et al. (1977) and Caron (1983) with the glycerol added to reduce the damage of particularly small delicate protists during filtration as described in Sazhin et al. (2007). FlowCAM analysis of mesocosm seawater The FlowCAM was run in autoimage-mode, using 4x magnification to analyze particles ranging between 15 and 1000 µm. The water samples were kept in dim light at 4°C until analyzed, within 4 h after sampling. Each sample was run for ca. 30 min, corresponding to 5.7 ml of analyzed volume. The relevant context capture property chosen to do the analysis was distance to nearest neighbor = 50 µm. All the image collages were manually post-analyzed in order to identify the particles in question. Particle sizes were estimated from area-based diameter determined by the FlowCAM VISP 2.2 software following Jakobsen & Carstensen (2011). Colonies of P. pouchetii are composite clusters of cells spaced in colonies of various sizes. When the colonies are forming dense blooms, the FlowCAM cannot distinguish whether a cluster is a part of colony or if a cluster is a part of a neighbouring colony. The FlowCAM therefore captures clusters of colonies. S. marinoi and P. pouchetii are colonial structures of multiple cells, and we developed scaling relationships between colony area and cell number by manually counting the number of cells in either a diatom chain or a P. pouchetii colony (n > 100) and related the cell number to particle area. We further developed scaling relationships between cluster areas by manually counting the number of cells in P. pouchetii clusters (n > 100). The same procedure was used for estimating S. marinoi cells, where we manually counted the number of cells per chain. The cell numbers were related to either cluster area (P. pouchetii clusters) or chain length (S. marinoi), and the relationships were then used to estimate the total number of P. pouchetii or S. marinoi cells in colonies or chains, respectively, by sample. Cell concentrations were estimated by correcting for the analyzed volume. The resulting regression equation used for estimation the number of P. pouchetii cells in colonies and colony fragments was Cells = ABD 1.834 * 0.028 (R 2 = 0.83), where ABD (area base diameter) is an output parameter from

Replacement of filters for respirable quartz measurement in coal mine dust by infrared spectroscopy

ABSTRACTThe objective of this article is to compare and characterize nylon, polypropylene (PP), and polyvinyl chloride (PVC) membrane filters that might be used to replace the vinyl/acrylic co-polymer (DM-450) filter currently used in the Mine Safety and Health Administration (MSHA) P-7 method (Quartz Analytical Method) and the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods 7603 method (QUARTZ in coal mine dust, by IR re-deposition). This effort is necessary because the DM-450 filters are no longer commercially available. There is an impending shortage of DM-450 filters. For example, the MSHA Pittsburgh laboratory alone analyzes annually approximately 15,000 samples according to the MSHA P-7 method that requires DM-450 filters. Membrane filters suitable for on-filter analysis should have high infrared (IR) transmittance in the spectral region 600–1000 cm−1. Nylon (47 mm, 0.45 µm pore size), PP (47 mm, 0.45 µm pore size), and PVC (47 mm, 5 µm pore size) filters meet this specification. Limits of detection and limits of quantification were determined from Fourier transform infrared spectroscopy (FTIR) measurements of blank filters. The average measured quartz mass and coefficient of variation were determined from test filters spiked with respirable α-quartz following MSHA P-7 and NIOSH 7603 methods. Quartz was also quantified in samples of respirable coal dust on each test filter type using the MSHA and NIOSH analysis methods. The results indicate that PP and PVC filters may replace the DM-450 filters for quartz measurement in coal dust by FTIR. PVC filters of 5 µm pore size seemed to be suitable replacement although their ability to retain small particulates should be checked by further experiment.

Interactions of ciprofloxacin (CIP), titanium dioxide (TiO2) nanoparticles and natural organic matter (NOM) in aqueous suspensions

The aim of the present study was to investigate interactions of the antibiotic ciprofloxacin (CIP), titanium dioxide nanoparticles (TiO2 NP) and natural organic matter (NOM) in aqueous suspensions. The mean hydrodynamic diameter of particles of TiO2 NP and NOM in the suspensions ranged from 113 to 255nm. During batch experiments the radioactivity resulting from 14CIP was determined in the filtrate (filter pore size 100nm) by scintillation measurements.Up to 72h, no significant sorption of NOM to TiO2 NP was observed at a TiO2 NP concentration of 5mg/L. When the concentration of TiO2 NP was increased to 500mg/L, a small amount of NOM of 9.5%±0.6% was sorbed at 72h. The low sorption affinity of NOM on TiO2 NP surfaces could be explained by the negative charge of both components in alkaline media or by the low hydrophobicity of the NOM contents.At a TiO2 NP concentration of 5mgL−1, the sorption of CIP on TiO2 NP was insignificant (TiO2 NP/CIP ratio: 10). When the TiO2 NP/CIP ratio was increased to 1000, a significant amount of 53.6%±7.2% of CIP was sorbed on TiO2 NP under equilibrium conditions at 64h. In alkaline media, CIP is present mainly as zwitterions which have an affinity to sorb on negatively charged TiO2 NP surfaces. The sorption of CIP on TiO2 NP in the range of TiO2 NP concentrations currently estimated for municipal wastewater treatment plants is estimated to be rather low. The Freundlich sorption coefficients (KF) in the presence of NOM of 2167Lnmgmg−nkg−1 was about 10 times lower than in the absence of NOM. This is an indication that the particle fraction of NOM<100nm could play a role as a carrier for ionic organic micro-pollutants as CIP.

Human adipose-derived stem cell isolation from fat tissues by membrane filtration method via nylon net filters having different pore sizes

Event Abstract Back to Event Human adipose-derived stem cell isolation from fat tissues by membrane filtration method via nylon net filters having different pore sizes Hong-Ren Lin1, Saradaprasan Muduli1, Yi Tung Lu1 and Akon Higuchi1, 2 1 National Center University, Chemical engineering and material science, Taiwan 2 College of Science, King Saud University, Department of Botany and Microbiology, Saudi Arabia Human adult stem cells, such as human adipose-derived stem cells (hADSCs), are considered to be a more attractive source of stem cells than human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). This is because human adult stem cells do not generate the ethical concerns that accompany hESCs. The hADSCs exhibit heterogeneous characteristics, indicating various genotypes and differentiation abilities. The isolated hADSCs can possess different purity levels and divergent properties depending on the purification methods used[1]. In order to make sure the importance and difference between different pore sizes, we decided the nylon mesh filter with pore size from 11 to 60 mm. Fig. 1 hADSCs purification by membrane migration method. We developed a hybrid-membrane migration method that purifies hADSCs from a fat tissue solution with extremely high purity and pluripotency. Digest fat tissue with 0.75% collagenese for 1 hour, obtained a primary fat-tissue solution and permeated it through the porous membranes with a pore size from 11 to 60 mm by the membrane filtration method, and the membranes were incubated in cell culture medium for 15-18 days to expand cell number and run flow-cytometer and qRT-PCT to analysis purity and pluripotent gene expression. Fig. 2 Purity of hADSCs after filtration and purified by membrane migration method through 11, 20, 41 and 60 µm pore size of nylon mesh filter. The hADSCs that migrated from the membranes contained an extremely high percentage (e.g., >90%) of cells positive for mesenchymal stem cell markers and the cells isolated by membrane filtration method showed higher expression of some pluripotency genes (Oct4, Sox2, klf4 and Nanog) compared with the cells isolated using the conventional culture method. When pore size is smaller then 20 mm, it could remain high purity hADSCs. The smaller pore size had higher purity and pluripotency.

A Standardized Method for the Preparation of a Gas Phase Extract of Cigarette Smoke.

The gas phase of cigarette smoke is important from the viewpoint of human health, because it can pass through alveolar epithelium and enter the circulation. There is no standard method for the preparation of a gas phase extract of cigarette smoke (CSE), although CSE is widely used for research instead of whole cigarette smoke. We have established a standard method for the preparation of CSE. One cigarette per trial is continuously combusted under a reduced pressure generated by an aspiration pump with a velocity of 1.050 L/min: the main stream of the smoke is passed through a Cambridge filter to remove tar, and subsequently, bubbled through a glass ball filter (pore size, 20-30 µm) into 15 mL of phosphate-buffered saline (PBS). To express the concentration of CSE, a virtual tar concentration is introduced, which is calculated assuming that tar trapped on the Cambridge filter is dissolved in the PBS. CSEs prepared from smaller numbers of cigarettes (original virtual tar concentration≤15 mg/mL) show similar concentration-response curves for cytotoxicity versus virtual tar concentrations. CSEs prepared from various brands of cigarettes and by different smoking regimes (continuous and puff smoking) show similar cytotoxic potency if the virtual tar concentrations are the same. In conclusion, using the standardized method for CSE preparation in combination with the virtual tar concentration, it becomes possible to simply and rapidly prepare standard CSEs with defined concentrations from any brand of cigarettes, which are toxicologically equivalent to CSE prepared by puff smoking.

Facile synthesis of reduced graphene oxide–gold nanohybrid for potential use in industrial waste-water treatment

Here, we report a facile approach, by the photochemical reduction technique, for in situ synthesis of Au-reduced graphene oxide (Au-RGO) nanohybrids, which demonstrate excellent adsorption capacities and recyclability for a broad range of dyes. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) data confirm the successful synthesis of Au-RGO nanohybrids. The effect of several experimental parameters (temperature and pH) variation can effectively control the dye adsorption capability. Furthermore, kinetic adsorption data reveal that the adsorption process follows a pseudo second-order model. The negative value of Gibbs free energy (ΔG0) confirms spontaneity while the positive enthalpy (ΔH0) indicates the endothermic nature of the adsorption process. Picosecond resolved fluorescence technique unravels the excited state dynamical processes of dye molecules adsorbed on the Au-RGO surface. Time resolved fluorescence quenching of Rh123 after adsorption on Au-RGO nanohybrids indicates efficient energy transfer from Rh123 to Au nanoparticles. A prototype device has been fabricated using Au-RGO nanohybrids on a syringe filter (pore size: 0.220 μm) and the experimental data indicate efficient removal of dyes from waste water with high recyclability. The application of this nanohybrid may lead to the development of an efficient reusable adsorbent in portable water purification.

杏林湾水体的硝化作用及其影响因素研究

文章采用现场调查结合实验室模拟培养，研究了2011年8月和2012年2月杏林湾表层水体溶解无机氮的分布、硝化作用强度及其影响因素。结果表明，杏林湾水体溶解无机氮和硝化作用强度的空间差异和季节变化显著，湾区上游和下游的溶解无机氮的浓度和硝化速率均比中游高，夏季溶解无机氮的浓度和硝化速率比冬季高，说明溶解无机氮的浓度和温度是控制硝化作用空间变化和季节变化的主要因素。实验室培养的结果表明，温度、pH、氨的浓度和颗粒物对硝化菌的硝化作用均有重要的影响，其中温度和颗粒物对硝化作用强度影响最为显著。在20℃~30℃之间，温度升高10℃硝化速率提高2.9倍；水样经3 μm的滤膜过滤去除颗粒物后，硝化作用强度减弱为原水的1/5。pH对硝化作用有较大影响，当pH值为8.0时，硝化速率最大。当氨的浓度< 3.0 mg∙N∙L−1 (即214 μmol∙N∙L−1)时，提高氨浓度可有效促进硝化作用，但是较高的氨浓度、较高的温度反而会抑制硝化作用，反映了微生物对长期生境的适应性。根据实验结果估算，硝化作用可以把输入杏林湾水体的38%~52%的氨氮转化为硝氮，对区域氮循环具有重要意义。 The spatial distribution and seasonal variation of dissolved inorganic nitrogen, the performance of nitrification and its impact factors in Xinglin Bay were investigated based on field observation and laboratory simulation incubations in August 2011 (summer) and February 2012 (winter). The results showed that the inorganic nitrogen and nitrification rates had significant spatial and seasonal variation. The relative higher concentrations of inorganic nitrogen coupling with higher nitrification rates were observed at the upstream and downstream of the Bay as compared to the middle stream, suggesting that inorganic nitrogen was the major factor affecting the spatial distribution of nitrification. Seasonally, the concentrations of inorganic nitrogen and nitrification rates were higher in summer than that in winter, indicating that inorganic nitrogen concentrations and the water temperature were the major factors affecting the seasonal variation of nitrification in the Bay. The laboratory experiments showed that temperature, pH, ammonia concentration and particulate matter had important effects on nitrification. Especially, the temperature and particulate mater had significant effects on nitrifying capacity. The increase of 10˚C of temperature, the nitrification rate could be increased by 2.9 times within the temperature range 20˚C - 30˚C. The nitrification rate in the filtered water (through ~3 μm pore size filter) was only 1/5 of that in unfiltered water. At low concentration ( -N < 3 mg∙L−1), the increase of ammonia concentration could enhance the nitrification. However, higher temperature and ammonia concentration could inhibit the process of ni-trification. The optimum conditions for nitrification were pH 8.0, temperature 30˚C and ammonia concentration 3.0 mg∙N∙L−1, indicating that the microorganism adapted to the long-term habitat. It was estimated that around 38% - 52% of input ammonia was removed by nitrification in water column in the Bay, suggesting that nitrification was important on nitrogen cycle in Xinglin Bay.

本州日本海沿いの遠隔地における降雪中の無機小球体粒子の組成と長距離輸送

In order to investigate the long-range transfer mechanism of inorganic small spherical particles in wet-depositions on mountains and remote areas along the Japan Sea in Honshu Island, Japan in 2014 and 2015, other than the summit of Mt. Kajigamori in Shikoku Island, Japan, the residue was obtained with a 0.45 μm pore-sized filter and a single-particle analysis was carried out for ones below 3 μm by using a Low-Vacuum Tabletop SEM-EDX. Particles were classified in six categories according to their compositions. In this work, it was found that a new category type of distribution patterns of the particles (Al-Si particle) was presented, and proposed that depended on the 24 h back-trajectory in Russia near the coast area of Japan Sea. Relationship between classification and back trajectory of air mass was investigated and discussed.

Determination of Filter Pore Size for Use in HB Line Phase II Production of Plutonium Oxide

The Savannah River Site’s H-Canyon and HB-Line are tasked with the production of plutonium oxide from a feed of plutonium metal for the Mixed Oxide (MOX) Fuel Fabrication Facility. The work presented here followed the general precipitation methods used at SRS to determine the quantity of solids present in the filtrate and to recommend an alternate filtration strategy. Initial Pu losses were found to be less than 1.5%. With additional filtration, this study indicates that a 50% further reduction in Pu solids in the filtrate can be achieved by the addition of a 2 μm filter.

A Novel Method for Preparing Surface-Modified Fluocinolone Acetonide Loaded PLGA Nanoparticles for Ocular Use: In Vitro and In Vivo Evaluations.

Our objective was to prepare nanoparticulate system using a simple yet attractive innovated method as an ophthalmic delivery system for fluocinolone acetonide to improve its ocular bioavailability. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by adopting thin film hydration method using PLGA/poloxamer 407 in weight ratios of 1:5 and 1:10. PLGA was used in 75/25 and 50/50 copolymer molar ratio of DL-lactide/glycolide. Results revealed that using PLGA with lower glycolic acid monomer ratio exhibited high particle size (PS), zeta potential (ZP) and drug encapsulation efficiency (EE) values with slow drug release pattern. Also, doubling the drug concentration during nanoparticles preparation ameliorated its EE to reach almost 100%. Furthermore, studies for separating the un-entrapped drug in nanoparticles using centrifugation method at 20,000rpm for 30min showed that the separated clear supernatant contained nanoparticles encapsulating an important drug amount. Therefore, separation of un-entrapped drug was carried out by filtrating the preparation using 20-25μm pore size filter paper to avoid drug loss. Aiming to increase the PLGA nanoparticles mucoadhesion ability, surface modification of selected formulation was done using different amount of stearylamine and chitosan HCl. Nanoparticles coated with 0.1% w/v chitosan HCl attained most suitable results of PS, ZP and EE values as well as high drug release properties. Transmission electron microphotographs illustrated the deposition of chitosan molecules on the nanoparticles surfaces. Pharmacokinetic studies on Albino rabbit's eyes using HPLC indicated that the prepared novel chitosan-coated PLGA nanoparticles subjected to separation by filtration showed rapid and extended drug delivery to the eye.