Shell Samples Research Articles

Microstructure evolution and mechanical behaviors of alumina-based ceramic shell for directional solidification of turbine blades

The high temperature mechanical behaviors of Al2O3-based ceramic shell for the directional solidification of turbine blades were investigated. Isothermal uniaxial compression tests of ceramic shell samples were conducted on a Gleeble-1500D mechanical simulator with an innovative auxiliary thermal system. The microstructures of sintered, heat-treated, and tested samples were characterized using scanning electron microscope and X-ray powder diffraction. The experimental stress–strain results of heat-treated samples were obtained. The eutectic mixture region composed of ZrO2 and SiO2 that regenerated by the decomposition reaction of excess zirconium silicate appears in the samples after heat treatment at 1500. The fracture type of CST25 and CST700 is brittle fracture, but CST1100 and CST1400 have thermo-viscoelastic and viscoplastic properties under stress conditions at high temperatures (>1100). The evolution of zirconium silicate decomposition reaction during the directional solidification process is analyzed. The SiO2 particles provide the major viscosity source of the ceramic shell at high temperatures. The thermo-viscodamage constitutive model of Al2O3-based ceramic shell for the directional solidification of single crystal superalloy is established.

Biomass residue characterization for their potential application as biofuels

A detailed understanding of chemical composition and thermal degradation behavior is very important for a biomass before processing it into a pyrolysis or gasification unit for energy production. In the present work, the physico- and thermo-chemical characterization of four different types of walnut shells (PSW, TSW, MSW and HSW) is carried out to evaluate their application as furnace oil. The thermal degradation behavior during the thermal decomposition of different walnut shells (WS) samples is studied using thermogravimetric analysis at three different heating rates (5, 10 and 15 °C min−1). It is observed that the complete moisture removal is below 152 °C, and the degradation of lignocellulosic biomass is occurred between ≈ 250 to ≈ 400 °C in the oxidizing atmosphere. For all different WS samples, the heating values are observed in the range of 13.8–18.4 MJ kg−1, which is comparable to the wood waste and lignite coal. The cellulose, hemicellulose, lignin and extractives in walnut shell are found to vary from 32.3 to 34.5, 21 to 27, 39 to 43 and 1.4 to 1.7%, respectively. The functional characterization of different WS is carried out using FTIR, and the most prominent FTIR band peak has been found at wave numbers of 3400, 2931, 1420 and 1050 cm−1, which is due to the stretching vibrations of –OH, CH–, aromatic C=C, and aliphatic ether and alcohol groups, respectively. Scanning electron microscopy analysis indicated the rough texture and heterogeneous structures of biomass. Further, the X-ray diffraction analysis showed the crystalline structure, which is due to the presence of cellulose. Therefore, it can be concluded that the walnut shell is a potential candidate for energy generation through thermo-chemical conversion.

Kinetic parameter evaluation of groundnut shell pyrolysis through use of thermogravimetric analysis

With growing interest in environmentally-friendly sources of energy, biofuel and pyrolysis are increasingly seen as potential solutions. In this study, the pyrolysis of groundnut shell is being investigated, with the intention of determining key kinetic parameters to provide a deeper understanding of the chemical process. A small sample of groundnut shell was pyrolyzed at different heating rates of 10, 20 and 30 K min−1. The thermogravimetric data was used to compare various kinetic models: including a single reaction, consecutive reaction, and distributed activation energy model. The results showed that the consecutive reaction model best described the process when both reactions were set to the second order.

OCCURRENCE OF HELICOBACTER SPECIES WITH SPECIAL PRIORITY TO H. PYLORI IN HEN'S EGGS

A total of 300 random eggs, representing 60 samples, (30 from baladi hens, and 30 from poultry farms) were collected from different markets, poultry farms, groceries and supermarkets located in Assuit governorate, Egypt. Each egg sample composed of 5 eggs and these samples were examined for the incidence of Helicobacter species using Helicobacter pylori special peptone agar (HPSPA). The results revealed that the incidence of Helicobacter species from examined baladi hen's egg shells was 10 (33.33%), poultry farms hen's egg shells was 9 (30%) and 1(3.33%) from examined baladi hen's egg content samples. H. pylori was isolated in a percentage of 5 (16.67%) from examined baladi hen's egg shells while from poultry farms hen's egg shells was 4 (13.33%). In addition, otherHelicobacter species were isolated from the examined samples as H. cinaedi in a percentage of (6.67%) from examined baladi hen's egg shells and (10%) from examined poultry farms hen's egg shells. H. felis was isolated in a percentage of (6.67%) from both examined baladi and poultry farms hen's egg shells samples and H. pullorum was isolated in a percentage of (3.33%) from examined baladi hen's egg shells. Also, it wasisolated from examined baladi hen's egg contents in a percentage of (3.33%). Identification of ureC gene for H. pylori isolated from both baladi hen's egg shells and poultry farms hen's egg shells by using polymerase chain reaction (PCR) revealed that 8 from 9 samples were positive for H. pylori by using (PCR) in a percentage of (88.89%).

Efficiency comparison of two types of almond shell in removal of mercury from aqueous solution

Background: Mercury is a heavy metal with high toxic effects. It has many apply to various industries, so can enter to the environment from different resources. Therefore, its elimination from wastewater is a major challenge. In this study, removal of mercury from aqueous solution using two types of almond shell was investigated and compared. Methods: This experimental-intervention study has been conducted in a batch method. At the beginning, the almond shell samples were collected and prepared. Then the effect of parameters affecting the adsorption such as pH, the amount of sorbent, the initial ion concentration and contact time were investigated and optimized. At the end efficiency of two shells were compared using f-test and t-test. Results: The most mercury removal was achieved at pH = 5.5± 0.1 in 10 min initial contact time. The obtained maximum adsorption capacity corresponding to Langmuir isotherm model (for 5 and 7 gram per liter of sorbent) were 135/13 ± 8.34 and 105.30 ± 7.92 for hard and soft shell, respectively. Difference was statistically significant (P= 0.0005). Conclusion: Although both of the adsorbents have high efficiency in removal of mercury from aqueous solution in comparison of other natural adsorbents but the result showed that mercury adsorption capacity by almond hard shell was more than almond soft shell. This sorbent as a simple, inexpensive, accessible, and without producing waste materials may proposed to industries which produce wastes including mercury.

Bioaccumulation Of Heavy Metal Mercury (Hg) In Rain Season In Culture Of Green Mussel (Perna viridis) On Cirebon Water, West Java

A Study was conducted to determine the bioaccumulation of heavy metal mercury (Hg) by the tissue of Perna viridis (green mussel), water, and sediment collected from culture of green mussel in Cirebon water, West Java on rainy season February 2018. Sediments, green shells of P. viridis, and water were taken from the culture of green mussel of Cirebon waters. Samples were taken during the rainy season in February at harvest age ie 6 months of maintenance. Seawater, sediment, and green shell samples were taken 3 replications. Testing of mercury (Hg) heavy metals follows SNI 01-2354.6-2006 measured in the laboratory of Research and Development Guidance of Quality of Fishery Products (BPPMHP) Cirebon, West Java. Based on the results of the research, it is known that the content of heavy metals mercury (Hg) in sediments of 0.003 ± 0.006 ppm, green mussel P. viridis 0.027 ± 0.038 ppm, water 0.017 ± 0.029 ppm. Keywords: Green mussel, heavy metal mercury, rainy season, Cirebon water

PENENTUAN PARAMETER ADSORPSI SILIKA SINTETIK DARI CANGKANG KELAPA SAWIT TERHADAP KANDUNGAN AMMONIUM PADA LIMBAH CAIR TAHU

[DETERMINATION OF SYNTHETIC SILICA ADSORPTION PARAMETERS OF OIL PALM SHELLS AGAINST THE CONTENT OF AMMONIUM ON LIQUID TOFU WASTE] This research aims to determine adsorption capacity of synthetic silica synthesized from Palm Oil (Elaeis guineensis Jacq) shells ashes against the content of Ammonium on tofu liquid waste . The shell sample soaked in a solution of HCl 10% for 2 hours, charred at a temperature of 300 °C for 3 hours ago ashed at 600 °C for 2 hours. Then ash soaked with HCl 1.2 M for 24 hours. Taken 120 g of ash shells and then mixed right while heated with 160 mL 4 M NaOH. The residue obtained is heated at a temperature of 5000 °C for 30 minutes, cooled to room temperature and retrieved the Na2SiO3 particle.The particle then dissolved into 200 ml aquademin and settled at 12 hours, filtered and filtratnya ditetesi with HCL 1 M while stirring, until the white gel is formed and settled in the next 24 hours, filtered, and dried at a temperature of 120 °C for 2 hours, an silica powder obtained as result. Ammonium Adsorption is done with mass variation 0125, 0.25, 0.5, 0.75, and 1 g silica as well as variations of the contact time of 15, 30, 60, 90, and 120 minutes. The results showed Ammonium adsorption at tofu liquid waste by silica synthesis from the Palm Oil shell ashes occurs with a maximum mass of 0.25 g and optimum contact time of 30 minutes with a capacity of adsorption of 2.581 mg/L and 3,154 mg/L as well as with adsorption efficiency at 61.9% and 76.8%.

Radiocarbon dating of aquatic gastropod shells and its significance in reconstructing Quaternary environmental changes in the Alashan Plateau of northwestern China

Using landform evolution and lake sediment records to reconstruct Quaternary environmental changes requires reliable chronology. However, there is an ongoing debate regarding the fossil shells of aquatic gastropods in carbonate rock area to be used for radiocarbon dating. The focus of this debate is whether living gastropods incorporate the dead carbon, which would affect the accuracy of the dating results. Living aquatic gastropods were selected from habitats on carbonate terrain in arid region. In this study, 64 shell samples from living gastropods, including Cipangopaludina chinensis, Gyraulus convexiusculus, and Radix auricularia, collected from the Alashan Plateau of northwestern China, were dated by accelerator mass spectrometry (AMS) 14C dating. The results revealed that only five samples (~8%) from the same site contained no dead carbon. The other 59 samples (~92%) contained dead carbon in various amounts: ~59% samples contained 0–10% dead carbon, and ~33% samples contained more than 10% dead carbon. Of the samples, 56 were Radix auricularia and their 14C ages varied from present to 3253 cal yr BP. Two of the samples were Gyraulus convexiusculus samples dated at 379 and 290 cal yr BP which are highly consistent with 14C ages of Radix auricularia samples from the same site. The other six Cipangopaludina chinensis samples were dated at 407–863 cal yr BP. Thus, most of living aquatic gastropods from habitats on carbonate terrain contained dead carbon. The amount of dead carbon in the gastropod shells was nonselective among the three species. Radiocarbon dating of aquatic gastropod shells may not be useful for studying processes that occurred over multi-millennial timescales at different localities in areas of carbonate rock. It is difficult to establish high-resolution chronologies using 14C ages of gastropod shells in arid regions with carbonate rocks unless the limestone effect has been corrected.

Screening cyanobacteria from marine coastal waters of Thailand for biohydrogen production

Cyanobacteria are prokaryotic organisms capable of oxygenic photosynthesis. H2 can be produced by cyanobacterial bidirectional hydrogenase, but mainly during anaerobic dark fermentation. Here, we screened H2 producing cyanobacteria isolated from marine environments in Thailand and optimized physiological conditions for maximizing H2 production of the selected isolate. Most of the 54 cyanobacterial strains isolated and purified from samples of seawater, stones, sand, and shells in the Gulf of Thailand and the Andaman Sea, southern part of Thailand produced H2 when cells were incubated in nitrogen-deprived medium under dark/anaerobic condition. The filamentous non-heterocystous cyanobacterium Geitlerinema sp. RMK-SH10 gave the highest H2 yield with highest H2 production rate found in 7-day grown cells. Geitlerinema sp. RMK-SH10 showed maximum H2 production rate of 0.271 ± 0.013 μmol H2 mg−1 dry weight h−1 when incubated in NaNO3-free ASN III medium containing 0.2 M NaCl, 18.9 mmol C-atom of glucose L−1, and 0.1 μM Ni2+. These results suggest that the marine filamentous cyanobacterium Geitlerinema sp. RMK-SH10 has high potential as a H2 producer amenable for further improvement by genetic manipulation.

Geochemical and Microstructural Signals in Giant ClamTridacna maximaRecorded Typhoon Events at Okinotori Island, Japan

AbstractTo validate the usability of the giant clam shell as a recorder of short‐term environmental changes such as typhoons, we collected a liveTridacna maximafrom Okinotori Island, Japan, on 15 June 2006. Growth increment thickness, stable isotope ratio (δ18Oshell, δ13Cshell), and the barium/calcium ratio (Ba/Ca) in theT. maximashell sample were measured and compared to Okinotori Island instrumental environmental data. In the outer layer of the shell sample, there were 365 ± 6 growth increments per year, as estimated by the δ18Oshellprofile compared with sea surface temperature. The growth increments in the specimen were formed daily, and thus, we can determine the date of the sampling points of δ18Oshell, δ13Cshelland the Ba/Ca ratio by counting growth increments. After typhoon approach, there is a decrease in increment thickness and some disturbed growth increments. The positive peaks in the shell Ba/Ca ratio and δ18Oshellcorresponded to lower sea surface temperature caused by typhoons. These results indicated that the microstructural and geochemical record inTridacna maximashells could be useful for detecting past typhoon events.

Sr/Ca ratio analysis of seashells using laser-induced breakdown spectroscopy under objective-lens focusing and single-lens focusing.

Laser-induced breakdown spectroscopy (LIBS) is a new technique for seashell elemental analysis, and now that application is in rapid development. In this work, LIBS was applied for scallop shell [Chlamys (Azumapecten) farreri] analysis using the element ratio Sr/Ca, and the analytical result was compared under objective lens (OL) focusing and single lens (SL) focusing, respectively. It is interesting to find that, under the two focusing arrangements, the ratio (Sr/Ca) variation on the shell cross section performed completely differently, while in technical aspects, the two focusing arrangements presented almost the same characteristics in a standard sample. Also, the seashell annual growth could be well indicated by high values of Sr/Ca intensity ratio when using OL, but under SL focusing no pattern was found. The difference of shell sampling amount and size might be the reason for inconsistent analysis performance under the two focusing arrangements. The scanning electron microscopy (SEM)-energy dispersive spectrometer (EDS) scanning results of the shell proved that LIBS analysis under OL focusing was closer to the actual Sr/Ca distribution than that under SL focusing. The obtained results might be useful for the methodology of LIBS in seashell applications.

<sup>14</sup>C ages of shell and charcoal samples excavated from Nagarabaru-3 Shell Mound and Kayabaru A-Site, southern coast of Ie Island, Okinawa Prefecture

<sup>14</sup>C ages of shell and charcoal samples excavated from Nagarabaru-3 Shell Mound and Kayabaru A-Site, southern coast of Ie Island, Okinawa Prefecture

Bacteriological evaluation of quail eggs from different farms in Egypt

Bacterial contamination of Japanese quail eggs (Coturnix coturnix) possibly affects quality of eggs and transmits pathogens that cause food borne infection or intoxication to consumers. Six hundred quail eggs which represented 100 composite samples (each one sample consisted of 6 eggs) were randomly collectedfrom different farms in Egypt. The egg shells and contents were examined bacteriologically. The obtained results showed that average values of Total Bacterial Count, Enterobacteriaeae and Coliforms in egg shell samples were 1.4x105, 3.7x102 and 2.2x102 cell/ ml respectively. But in egg contents, the corresponding counts were (5.5 x103, 8.0 x10 and 1.9x10 cell/ml). Prevalence of Salmonella from the quail egg samples was 9 % (shell) and 2% (content). However, the prevalence of E. coli in quail eggs samples was 11 % (shell) and 3% (content). After biochemical and serological examination, 13 strains of Salmonella were positive, the most frequent species were S. Entertitidis, S.Typhimurium and S.kentuckey. While 16 strains of E. coli were isolated and belonged to EPEC, ETEC, EHEC pathotypes. PCR was done to detect some virulent genes of Salmonella as invA, STn and avrA genes. The results revealed that all strains were positive for these genes. So consumers must avoid consumption of raw quail eggs.

Acoustic Vibrations of Core–Shell Nanospheres: Probing the Mechanical Contact at the Metal–Dielectric Interface

The acoustic vibrations of metal–dielectric core–shell nanoparticles (Ag@SiO2 and Au@SiO2) are investigated using ultrafast pump–probe spectroscopy. The experimental results are in good agreement with calculations of the period of the breathing vibration of the core–shell particles. The transition from one overtone of the breathing mode to the next one as the size of the silica shell increases is observed for slightly thinner SiO2 shells than previously reported. Our results confirm that this optical technique permits the determination of the quality of the mechanical contact at the metal dielectric interface. This is of major importance for many applications, in particular because it modifies significantly the thermal conductivity at the nanoscale. Moreover, we observed that for two different synthesis routes, poor contact core–shell samples could sneak in among good sample series based on the same metallic core particles. This confirms the suitability of this all optical and noninvasive technique to obt...

The Marine Radiocarbon Reservoir Effect in Tomales Bay, California

ABSTRACTThis paper examines the marine reservoir effect for Tomales Bay, a 25.5-km-long tidal estuary along the northern coast of California. We determined the regional ∆R through radiocarbon (14C) measurements of pre-1950 shells from a museum collection as well as archaeologically recovered shell samples from a historical railroad grade of known construction date. These results are compared against four sets of paired shell and bone samples from two local archaeological sites. Our results indicate little spatial variation along the inner bay, but the proposed ∆R value is lower than those previously reported for nearby areas along the Pacific Coast. We also note potential variability in regional ∆R of approximately 200 14C years for the late Holocene, and comparison with an older paired bone and shell sample points toward more significant temporal variation earlier in time.

Utilization of Gamma Irradiated Aspergillus niger to Improve Oil Palm by-Product Digestibility

This study was conducted to determine the effect of fermentation using irradiated A. Niger on in vitro rumen fermentation characteristics of oil palm by-products. Completely randomized design with eight treatments and four replications was applied in this experiment. The treatments were kernel shell (CK), palm frond (PKS), oil palm empty bunches (TKKS), CK+PKS+TKKS (mix), fermented kernel shell (CKF), fermented palm frond (PKSF), fermented oil palm empty bunches (TKKSF) and fermented mix (mixF). The results showed that fermentation process reduced NDF content of PKS and TKKS by 7.42 and 7.09% respectively. Fermentation also decreased ADF content of TKKS by 7.35%. Maximum total gas production (a+b) of TKKS and mix sample decreased after fermentation process (P<0.05) by 52.92 and 35.60% respectively. Total VFA production increased on kernel shell and palm fronds samples after fermentation process (P<0.05) however CO2:CH4 ratio tended to be decrease. The conclusion of this study was the fermentation process by irradiated A. niger improved rumen fermentation characteristics of oil palm by-products, however more appropriate strategy is needed to reduce CH4 emissions.

Surface sulfurization of ZnO/ZnS core shell nanowires and shell layers dependent optical properties

With the unique properties and superior performance, ZnO/ZnS core shell nanostructures have been applied in many photoelectric devices. Varied growth methods can synthesize ZnO/ZnS core shell samples, which exhibit different crystal and optical properties, and have the positive or negative effect on performance of related devices. To investigate the growth and properties, ZnO/ZnS core shell nanowires were grown through surface sulfurization. X-ray diffraction and scanning electron microscopy measurements indicated surface sulfurization degree can affect crystal quality. In addition, photoluminescence results exhibited that ZnO/ZnS heterojunction emission properties were dependent on shell layers quality. By increasing the amount of surface powder, it would improve shell layers’ crystal quality. And with optimal surface sulfurization degree, the vacancies and interstitial atoms defects can be restrained, which may improve photo-generated carriers separation efficiency.

Highly selective and sensitive methanol gas sensor based on molecular imprinted silver-doped LaFeO3 core–shell and cage structures

Silver-doped LaFeO3 molecularly imprinted polymers (SLMIPs) were synthesized by a sol–gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core–shell (SLM-core–shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core–shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core–shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core–shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.

Carbon-shell-constrained silicon cluster derived from Al-Si alloy as long-cycling life lithium ion batteries anode

Although silicon is the most promising anode material for Li-ion batteries, large volume expansion during lithiation and delithiation is the main obstacle limiting the commercial application of silicon anodes. There are two ways to alleviate volume expansion and prevent further pulverization of a Si anode: fabrication of a rational nanostructure possessing void spaces and uniform distribution of the conducting sites, without a good balance effect in mitigating the limiting factors and enhancing battery performance. In this paper, we propose a novel nanostructure — a carbon-shell-constrained Si cluster (Si/C shell) with both adequate void space and good distribution of electrical contact sites to guarantee homogeneous lithiation in the initial cycle. Benefiting from the ability to maintain electrical conductivity of the outer carbon shell, even after cluster fragmentation, the Si/C shell synthesized from low-cost commercial Al-Si alloy spheres can deliver 0.03% capacity loss from 100th to 1000th cycles at a current density of 1 A g−1. The Si/C shell sample with the dual functional structure mentioned above can also maintain its own nanostructure during cycling and deliver excellent rate performance. It is a concise and scalable strategy which can simplify the preparation of other alloy anode materials for Li-ion batteries.

Study of formation of green eggshell color in ducks through global gene expression.

The green eggshell color produced by ducks is a threshold trait that can be influenced by various factors, such as hereditary, environment and nutrition. The aim of this study was to investigate the genetic regulation of the formation of eggs with green shells in Youxian ducks. We performed integrative analysis of mRNAs and miRNAs expression profiling in the shell gland samples from ducks by RNA-Seq. We found 124 differentially expressed genes that were associated with various pathways, such as the ATP-binding cassette (ABC) transporter and solute carrier supper family pathways. A total of 31 differentially expressed miRNAs were found between ducks laying green eggs and white eggs. KEGG pathway analysis of the predicted miRNA target genes also indicated the functional characteristics of these miRNAs; they were involved in the ABC transporter pathway and the solute carrier (SLC) supper family. Analysis with qRT-PCR was applied to validate the results of global gene expression, which showed a correlation between results obtained by RNA-seq and RT-qPCR. Moreover, a miRNA-mRNA interaction network was established using correlation analysis of differentially expressed mRNA and miRNA. Compared to ducks that lay white eggs, ducks that lay green eggs include six up-regulated miRNAs that had regulatory effects on 35 down-regulated genes, and seven down-regulated miRNAs which influenced 46 up-regulated genes. For example, the ABC transporter pathway could be regulated by expressing gga-miR-144-3p (up-regulated) with ABCG2 (up-regulated) and other miRNAs and genes. This study provides valuable information about mRNA and miRNA regulation in duck shell gland tissues, and provides foundational information for further study on the eggshell color formation and marker-assisted selection for Youxian duck breeding.