Thermal behaviour and phases evolution during the sintering of porous inorganic membranes

Anorthite-based highly porous membranes were successfully produced using calcined oyster shell to enhance the pore network. The calcined oyster shells produce CaO responsible for the crystallisation of gehlenite and anorthite at relatively low temperature. While the crystallisation produced nano and meso size of intergranular pores, vitrification of feldspar is responsible for development of the capillary porosities. The increasing sintering temperature from 1200 °C to 1300 °C implies the increase in average pores radius from 1.2 μm to 14.3 μm due to the formation of spherical pores from vitrification. The combination of different class of porosities in the matrices results in the interconnection with improvement of the permeability of the porous network. Porosity, permeability and chemical stability were improved with 20 wt.% of calcined oyster shell addition allowing the possible development of high strength porous network which is promising for the membranes support and other applications including liquid separation as well as liquid filtration where high pressure is used.     

Recycling von marinen Sekundärrohstoffen

As a waste product, oyster shells pose a major environmental pollution problem and the reuse of the material is becoming increasingly important. Since the comminution process in the recycling of secondary raw materials defines the properties of the material, oyster shells were grinded using a planetary ball mill and an impact mill and the fractions obtained were analyzed in terms of size and shape and compared with each other. A comminuted material from the impact mill was used for a series of wetting experiments, which helped to demonstrate the surface free energy of the material.     

Drawing in Time: Processes of Design and Fabrication

Drawing embeds time within itself, notating changes in space and duration. For Babak Bryan and Henry Grosman , founding partners of BanG studio in Long Island City, New York: ‘The drawing is a result of process, but it also describes process.’ It is only through this temporal practice that an essential connection is developed between drawing and building. With the widespread adoption of building information modelling (BIM), linear graphic representation finds itself in crisis, challenged by the static inertia of the model. As Bryan and Grosman describe, the well-crafted drawing remains essential to their studio's approach informing the method of ‘making and remaking’.     

Validation of two tropical marine bivalves as bioindicators of mining contamination in the New Caledonia lagoon: Field transplantation experiments

The bioaccumulation and retention capacities of some key local contaminants of the New Caledonia lagoon (Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn) have been determined in the oyster Isognomon isognomon and the edible clam Gafrarium tumidum during transplantation experiments. In a first set of experiments, oysters and clams from a clean site were transplanted into contaminated sites. Uptake kinetics determined in the field indicated that for Cr and Cu in oysters and Co, Ni, and Zn in clams, concentrations in transplanted bivalves reached those of resident organisms after 100d, whereas for the other elements, it would require a longer time for transplanted bivalves to reach the same levels as in the resident populations (e.g., up to 3 years for Cd). However, the slow uptake rate for metals observed in the latter transplantation is rather related to low bioavailability of metals at the contaminated sites than to low bioaccumulation efficiency of the organisms. Indeed, results of a second transplantation experiment into two highly contaminated stations indicated a faster bioaccumulation of metals in both bivalves. Results of both transplantations point out that the clam G. tumidum is a more effective bioindicator of mining contamination than I. isognomon, since it is able to bioaccumulate the contaminants to a greater extent. However the very efficient metal retention capacity noted for most elements indicates that organisms originating from contaminated sites would not be suitable for monitoring areas of lower contamination. Hence, geographical origin of animals to be transplanted in a monitoring perspective should be carefully selected.     

Lactulose production from milk concentration permeate using calcium carbonate-based catalysts

Milk concentration permeate (MCP), a low-value by-product of ultrafiltration plants and calcium carbonate-based catalysts were used for lactulose production. The results obtained show the effectiveness of oyster shell powder and limestone for lactose isomerisation as a replacement for egg shell powder. With the reaction conditions of 12 mg/ml catalyst loading, reflux time of 120 min at 96 °C, a maximum yield of 18–21% lactulose was achievable at a cost of <50% of original lactose degradation (measured by HPLC). De-proteination of MCP by acidification prior to isomerisation helped lactulose formation in the earlier stages, but did not significantly increase the yield. The resulting lactulose MCP (40 °B) incorporated at the rate of 3–4% was effective in enhancing the growth rate and acid production of Lactobacillus acidophilus (LA-5) in probiotic products.     

Norovirus contamination on French marketed oysters

Contaminated shellfish have been implicated in gastroenteritis outbreaks in different countries. As no regulation has been set up yet regarding viral contamination of food, very few data are available on the prevalence of contaminated products on the market. This study presents data obtained from oysters collected on the French market in one producing area over a 16 month period of time. Noroviruses were detected in 9% of samples with a seasonal impact and influence of climatic events. Contamination levels were low and, surprisingly, oysters sampled directly from the producer were found to have less contamination than oysters from supermarkets.     

Effects of high-pressure treatment on the microflora of oysters (Crassostrea gigas) during chilled storage

The microbiological quality of oysters high-pressure (HP)-treated in-shell at 260 MPa for 3 min, or 500 or 800 MPa for 5 min and then stored at 2 °C, were investigated. Microbial counts after HP treatment showed that the bacterial load was reduced after treatment at all pressures to levels below the detection limit. Randomly-selected isolates from the total aerobic viable counts of untreated and HP-treated oysters after 14 days of storage were identified by the API identification system. Bacteria isolated from oysters HP-treated at 260 MPa were Shewanella putrifaciens and Pseudomonas fluorescens. For oysters HP-treated at 500 or 800 MPa, the main bacteria isolated were Pseudomonas spp. Vibrio spp. comprised 44% of the microflora in untreated oysters after storage for 14 days at 2 °C, but no Vibrio were detected in HP-treated oysters. This study confirmed that HP processing can inactivate microorganisms and delay microbial growth in chilled stored oysters.

Industrial relevance

High-pressure (HP) treatment is being increasingly employed for commercial processing of oysters but no studies of the microflora of HP-treated in-shell oysters have been reported. HP treatment significantly changed the microflora of oysters and apparently has good potential for inactivation of Vibrio spp as HP treatment, in combination with adequate chilled storage, can improve the microbiological shelf-life and safety of oysters.     

Assessments of Fusion Methods Using WorldView-2 SatelliteImages for Coastal Oyster Culture Observation

Image fusion is one of the most important steps in remote sensing information extraction.To select the appropriate fusion method is the crucial link.In this paper,Xiangshan Port in Zhejiang Province is the study area,and the oyster culture is the observation target.The satellite of WorldView-2 multispectral and panchromatic images were used to detect the distribution of the coastal oyster farming.The different five fusion methods,such as Principal Component Analysis (PCA),Gram-Schmidt(GS),NNDiffuse Pan Sharpening,Brovey Transform and Wavelet Transform,were evaluated by two of subjective qualitative and objective quantitative aspects.We compared the fused images with the original image using six kinds of statistical parameters including mean,standard deviation,entropy,average grads,correlation coefficient and spectral distortion to evaluate the images’ fusion performance.The results indicate that,for the characteristics of coastal oyster farming,the fusion image by principal component analysis method not only preserves detail spatial texture information but also maintains the spectral character well.The method of PCA is the most suitable fusion method for remote sensing applications in coastal oyster culture with WorldView-2 images.The fusion effect of GS is second to PCA,which can be used as an alternate method for fusion applications.NNDiffuse Pan Sharpening,Wavelet transform and Brovey transform are inappropriate for the identification and extraction of oyster culture floating raft.     

贝壳资源的深加工利用

以牡蛎壳为原料,对其物相组成、结构等进行分析,然后将牡蛎壳进行煅烧,考察煅烧工艺对于产物氧化钙的活性、有效钙含量、白度以及微观结构等性能的影响,最后将煅烧产物进行消化和碳化,制备纳米碳酸钙.研究结果表明,牡蛎壳中碳酸钙为方解石晶型,含量高达95.87％,是一种优质的海洋生物碳酸钙资源.牡蛎壳煅烧过程中,随着煅烧温度的提...     

High Salinity Relaying to Reduce Vibrio parahaemolyticus and Vibrio vulnificus in Chesapeake Bay Oysters (Crassostrea virginica)

Cases of Vibrio infections in the United States have tripled from 1996 to 2009 and these infections are most often associated with the consumption of seafood, particularly oysters (Crassostrea virginica). Information is needed on how to reduce numbers of Vibrio parahaemolyticus and Vibrio vulnificus in bi‐valve molluscan shellfish (for example, oysters). The purpose of this study was to evaluate the effectiveness of high salinity relaying or treatment in recirculating aquaculture systems (RASs) as methods to reduce the abundance of V. parahaemolyticus and V. vulnificus in oysters. For relaying field trials, oysters were collected from approved harvest waters, temperature abused outside under a tarp for 4 h, and then transferred to high (29 to 33 ppt.) and moderate (12 to 19 ppt.) salinities. For RAS treatment trial, oysters were transferred to 32 to 34 ppt. salinity at 15 °C. After 7, 14, 21, and in some instances 28 d, oysters were collected and analyzed for V. parahaemolyticus and V. vulnificus levels using multiplex real‐time PCR. Initial levels of V. parahaemolyticus and V. vulnificus ranged from 3.70 to 5.64 log₁₀ MPN/g, and were reduced by 2 to 5 logs after 21 to 28 d in high salinity water (29 to 34 ppt.). Oyster mortalities averaged 4% or less, and did not exceed 7%. Relaying of oysters to high salinity field sites or transfer to high salinity RAS tanks was more effective in reducing V. vulnificus compared with V. parahaemolyticus. These results suggest that high salinity relaying of oysters is more effective in reducing V. vulnificus than V. parahaemolyticus in the oyster species used in this study.