Sixth Layers Research Articles

Research on oil well production analysis based on long-term slow-release tracer

Abstract Downhole monitoring the production profile is crucial for the development of oil and gas reservoirs. Currently, the commonly methods for monitoring the production profile include logging tools and using tracer monitoring. The tracer monitoring method is more popular in oil field operations due to its wide applicability, simple process, low cost, low risk, and long monitoring time. However, compared to traditional logging tool monitoring methods, tracer monitoring has drawbacks such as data lag, difficulty in downhole installation, and unstable long-term effects. Bohai Oilfield has developed a new type of solid tracer and solved the problem of downhole installation by improving the structure of the downhole screen tube. This tracer uses polymer material as the skeleton. After entering the designated position, the internal tracer can slowly diffuse into the solvent through the pores in the skeleton, achieving slow release and long-term monitoring of the production profile of the oil well. In 2023, this new type was first applied in the D6 well in Bohai Sea, and a half month stable production stage liquid production profile was obtained through sampling. The monitoring results showed that: (1) Solid slow-release tracer monitoring technology can continuously obtain production layer information in complex environments and can be used for short-term rapid water exploration and long-term water production monitoring, identifying water breakthrough time and main water breakthrough location, (2) The distance between water injection well and D6 production wells is small, and the water injection volume in the injection wells is large. The tracer monitoring results show that there is a certain degree of water flooding in all 6 sections of each test layer, (3) The first test layer is the main liquid production section, the first and sixth test layers are the main oil production sections, and the first and second test layers are the main water production sections. The research results can determine the oil and water production situation of each section of oil well, identify the water breakthrough time and water outlet position, and provide a basis for the next development adjustment.

Three-dimensional radiological anatomy of condyle trabecular bone based on a Volume-of-Interest analysis.

Three-dimensional radiological anatomic characteristics of condyle trabeculae was obtained quantitatively based on a volume-of-interest (VOI) analysis. Nine human mandibular condyle specimens were scanned by micro-computed tomography (micro-CT). A total of 34 VOIs were selected from each condyle specimen, which were divided into six layers and four parts to analyze the morphological characteristics of trabeculae based on cylindrical VOIs with a diameter and height of 2 mm. One-way analysis of variance was used to compare the regional differences of morphological parameters among each layer and part. Values for bone mineral density, bone volume/total volume, trabecular thickness, and trabecular bone number were greater in the anterior part compared with the posterior part; and the lateral part was larger than the medial part in the first, second, and third layers, while the medial part was larger in the fourth and fifth layers; these values in the first and sixth layers were much larger, while those in the third and fourth layers were smaller. Bone surface area/bone volume, trabecular spacing, and trabecular bone pattern factor were larger in the posterior part than in the anterior part; and the lateral part was larger than the medial part in the fourth and fifth layers, while the medial part was larger in the first and second layers. The morphological distribution of VOIs was anisotropic within trabecular bone of human mandibular condyles. The upper and lower ends of trabecular bone were much more compact, with higher bone density, trabecular thickness, and trabecular number than in the middle layers.

Midfacial Soft Tissue Changes After Reduction Malarplasty: A Computed Tomographic Study.

The reduction malarplasty has become one of the most popular esthetic surgeries among Asian women to improve facial contour. However, it is still controversial whether midfacial soft tissue changes after surgery, and more studies are needed. This retrospective observational study reviewed 30 patients who underwent L-shaped reduction malarplasty during January 2018 and August 2019. The preoperative and postoperative soft tissue thickness and the angle of nasolabial fold of the midfacial were assessed using photographs, three-dimensional skull computerized tomography images, and the Wrinkle Severity Rating Scale. The postoperative average level of nasolabial fold angle was lower than that observed in preoperative conditions, with the difference being statistically significant (t = -10.262, P < 0.001). The postoperative fifth and sixth layers of soft tissue in the midface were significantly higher than those observed in preoperative tissues. Although L-shaped reduction malarplasty has evident effects on soft tissue changes of middle face, they are within acceptable ranges and do not affect patient satisfaction.

Effect of incorporating aluminum wire mesh on the notched and un-notched strengths of glass fiber/epoxy composites

The fiber/metal composite technology consolidates the usefulness of metallic materials and fiber reinforced matrix systems. Glass laminate aluminum reinforced epoxy is a hybrid composite containing alternative thin layer of Aluminum (Al) plies and fiber reinforced epoxy. However, the low adhesion between Al thin layer and epoxy limits their application. In this work, we used Al wire meshes to toughen the neat E-glass fiber/epoxy composite. Un-notched and notched tensile and flexural tests were conducted to study the effect of incorporating Al wire meshes at different locations within the specimen thickness instead of the glass fiber plies on the mechanical properties of the produced materials. The results indicated that, incorporating Al mesh as a replacement of glass fibers could tailor the laminates strength, ductility and toughness. As the number of Al mesh layers increased, the specific tensile and flexural strengths decreased. The through-the-thickness position and orientation of Al mesh layer significantly affected the properties of the produced hybrid laminates. The presence of Al mesh at the outer layers highly reduced the tensile and flexural strengths. However, it improved the tensile and flexural strains and reaching an improvement of 54% and 117%, respectively. The energy absorption ability under tensile and flexural tests was highly improved with the addition of Al mesh layers reaching a maximum improvement of 210% and 166%, respectively. The mode I fracture toughness characterized by notched bending test was improved by 25.7% for samples with Al mesh layer replacing the third and sixth glass fiber layers.

Flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch (Astragalus sinicus L.) in response to pre-anthesis foliar application of paclobutrazol.

The number of grains per unit land area is the most important grain yield component in Chinese milk vetch. Flower and pod survival seem to be critical determinants of grain number, which is related to the number of fertile flowers and pods during the anthesis period. Flower and pod growth are frequently considered the key determinants to establish grain number. The objective of this study was to explore the influences of paclobutrazol on flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch under different concentrations of foliar spray and try to explore the physiological regulatory mechanisms. Field experiments were carried out during the 2017-2018 and 2018-2019 growing seasons at the Dayuzhuang experimental field. The experiment involved the Chinese milk vetch cultivar "Xinzi No. 1" and six levels of foliar application of paclobutrazol, 0, 200, 300, 400, 500, and 600 mg L-1, in treatments CK, T1, T2, T3, T4, and T5, respectively. Foliar spray was applied once, at the squaring stage. In comparison with the CK treatment, all of the paclobutrazol treatments yielded, to various degrees, increased values of the number of inflorescences per unit area, number of pods per unit area, grain-setting rate of pods, and number of grains per pod in all six inflorescence layers, with the largest increases observed in the T3 treatment. In the T3 treatment compared with the CK treatment, from the first to sixth inflorescence layers, the number of inflorescences per unit area was increased by 34.07-58.97%, the number of pods per unit area was increased by 39.69-68.35%, the grain number per pod was increased by 44.31-53.69%, and the grain-setting rate of pods was increased by 1.84-4.89%. An analysis of yield composition revealed that the paclobutrazol spray treatment had little impact on the grain weight of Chinese milk vetch. The correlations between the concentration of paclobutrazol spray and the grain yield of Chinese milk vetch reached a significant level. Grain yield was highest at the paclobutrazol concentration of 373.10 mg/L. The inflorescence contents of gibberellic acid 3 (GA3), indole-3-acetic acid (IAA), and abscisic acid (ABA) were reduced, whereas that of cytokinin (CTK) was increased, by foliar application of paclobutrazol (400 mg L-1, T3 treatment) relative to CK treatment during the stages of flowers and pods developing into grains.

Three-dimensional imaging study on the anatomical morphology of trabecular bone of the condyle based on the distribution of volume of interests

Objective: To analyze the anatomical morphological characteristics of the trabecular bone of human mandibular condyle by observing the distribution of volume of interests (VOI). Methods: The micro-CT images of a right condyle specimen of a 61-year-old adult male was analyzed in this study. The cylindrical VOI with both diameter and height of 2 mm were arranged, according to a certain pattern, as many as possible at various levels within the trabecular bone of the condyle. Each VOI had no intersection area. The selected VOI were divided into 5 parts: medial part, middle part, lateral part, anterior part and posterior part, with 6 layers from top to bottom. And the distribution of the overall anatomical morphological characteristics of three-dimensional (3D) images of the trabecular bone of the condyle was analyzed by using seven morphological parameters of each VOI, i.e. bone mineral density (BMD), bone volume/total volume (BV/TV), bone surface area/bone volume (BS/BV), trabecular thickness (Tb.Th), trabecular bone number (Tb.N), trabecular spacing (Tb.Sp) and trabecular bone pattern factor (Tb.Pf). Results: In the present study, totally 34 VOI were selected from the condyle specimen.The morphological distribution of the VOI was uneven in the 3D structure of the trabecular bone of the human condyle. BMD, BV/TV, Tb.N and Tb.Th were much higher at the middle part, while showed the smallest at the medial part. The anterior part demonstrated much higher parameters than the posterior part at the first, second, fifth and sixth layers, respectively, however, the posterior part showed much higher parameters than the anterior part at the third and fourth layers, respectively. The BMD was much higher at the first [(332.66±97.11) mg/cm3] and sixth [(255.79±45.68) mg/cm3] layers, while the lowest at the second layer [(255.79±41.06) mg/cm3]. The BV/TV and Tb.N were much higher at the first layer, with the lowest at the fifth layer. The Tb.Th at the first layer [(0.11±0.03) mm] was much higher than the others, which were similarly lower. The BS/BV, Tb.Sp and Tb.Pf were lower at the first layer and much higher at the medial and lateral parts, while were lower at the middle and anterior parts. The posterior part demonstrated much higher BS/BV, Tb.Sp and Tb.Pf than the anterior part at the first, fifth and sixth layers, respectively. However, the anterior part showed much higher scores than the posterior part at the third and fourth layers, respectively. The ANOVA results showed that the 7 morphological parameters of VOI were not statistically significant amongst the 6 layers (P>0.05). However, the 6 out of the 7 parameters, i.e. BV/TV, BS/BV, Tb.Th, Tb.N, Tb.Sp and Tb.Pf, were statistically significant amongst the five parts (P<0.05), while the only parameter of BMD was not statistically significant (P>0.05). Conclusions: The anatomical distribution characteristics of the trabecular bone of condyle were analyzed by using 3D imaging measurement based on the VOI. The results showed uneven distributions and indicated that the method of dividing the trabecular bone of mandibular condyle into VOI sets, which accorded with its specific anatomical characteristics, was feasible for further reference.

Fast and accurate detection of kiwifruit in orchard using improved YOLOv3-tiny model

Automatic detection of kiwifruit in the orchard is challenging because illumination varies through the day and night and because of color similarity between kiwifruit and the complex background of leaves, branches and stems. Also, kiwifruits grow in clusters, which may result in having occluded and touching fruits. A fast and accurate object detection algorithm was developed to automatically detect kiwifruits in the orchard by improving the YOLOv3-tiny model. Based on the characteristics of kiwifruit images, two convolutional kernels of 3 × 3 and 1 × 1 were added to the fifth and sixth convolution layers of the YOLOv3-tiny model, respectively, to develop a deep YOLOv3-tiny (DY3TNet) model. It takes multiple 1 × 1 convolutional layers in intermediate layers of the network to reduce the computational complexity. Testing images captured from day and night and comparing with other deep learning models, namely, Faster R-CNN with ZFNet, Faster R-CNN with VGG16, YOLOv2 and YOLOv3-tiny, the DY3TNet model achieved the highest average precision of 0.9005 with the smallest data weight of 27 MB. Furthermore, it took only 34 ms on average to process an image of a resolution of 2352 × 1568 pixels. The DY3TNet model, along with the YOLOv3-tiny model, showed better performance on images captured with flash than those without. Moreover, the experiments indicated that the image augmentation process could improve the detection performance, and a simple lighting arrangement could improve the success rate of detection in the orchard. The experimental results demonstrated that the improved DY3TNet model is small and efficient and that it would increase the applicability of real-time kiwifruit detection in the orchard even when small hardware devices are used.

Determination of groundwater potential and aquifer hydraulic characteristics in Agbor, Nigeria using geo-electric, geophysical well logging and pumping test techniques

Geo-electric, geophysical well logging and pumping test were carried out in Agbor, Nigeria to determine the groundwater potential and hydraulic properties of the aquifer in the study area. Twenty vertical electrical sounding were conducted across the study area using the Schlumberger configuration and the field result were curved matched and iterated using the Win Resist software. A borehole was sank in the study area, where soil cuttings were collected to construct the lithology of the subsurface. Geophysical well logging comprising of electrical conductivity and spontaneous potential logs and pumping test were also carried out in the well. The result of the geo-electric study revealed five to six geo-electric layers which consist of topsoil, lateritic sand, clayey sand, fine sand, medium coarse sand and coarse sand. Analysis of the geo-electric result revealed that the aquifer was located within the fifth and sixth layers at a depth which ranged from 29 to 82 m, while the resistivity of the aquifer ranged from 1741 to 29,395 Ωm. Result of the geophysical logging revealed that the electrical conductivity and total dissolved solid of the groundwater are 253 µS/cm and 165 mg/L, respectively. These values indicate fresh to moderate mineralization of the subsurface and are within the permissible limit set by the Standard Organization of Nigeria for good quality water. The result of the pumping test which was analysed using the Cooper Jacob method revealed that the transmissivity, specific capacity and storativity of the aquifer are 0.0036 m2/min, 0.02 m3/m and 0.016, respectively. These values showed that the aquifer is high yielding and will be able to provide adequate water for domestic, industrial and agricultural purposes for the people of the area.

Spin orbit coupling effects on the non-collinear magnetism of structurally relaxed Fe/Cu (001) thin films: First principles calculations

The effect of the spin–orbit coupling interaction and atomic relaxation, on the ground state non-collinear magnetism of deposited Fe thin films, on a Cu (001) surface, is studied by using first principles density functional theory calculations. The total energy values and spin and orbital magnetic local moments are calculated for a Fe film of N = 6 atomic layers deposited on a 12 layer thick Cu film playing the role of substrate. As a first step, we allow the thin film and surface layers to atomically relax. We found important contractions of about 20% between the first and second, the third and fourth, and firth and sixth Fe layers. Then, we obtain collinear and non-collinear magnetic arrangements which agree with the main experimental resultssatte that show a non-collinear configuration at low temperatures (around 40 K). The magnetic properties of the first four Fe layers are well reproduced. The agreement is better than the results obtained ignoring the spin–orbit coupling and the structure relaxation. Although both calculations predict non-collinear configurations with energy values slightly above that of a collinear ground state. In some cases, the energy differences between two collinear (or non-collinear) solutions with different spin orientation axis is only under the value of one meV. The calculated orbital local moment arrangements are clearly similar to the spin magnetic local moment ones and show a correct dependence on the dimensionality aspects of the system when changing the spin axis quantization direction.

Evaluation of groundwater supply potential from hydraulic parameters estimated from vertical electrical sounding (VES) in Ikeduru, south east Nigeria

A Vertical Electrical resistivity Sounding (VES) survey was carried out, to study the groundwater supply potential, protective capacity and soil corrosivity of aquifers in Ikeduru Local Government Area of Imo state, Nigeria. A total of ten (10) geoelectric soundings were acquired. Schlumberger electrode configuration was used in acquiring the data. Six to seven geoelectric layers were delineated from the interpreted results, the Aquifers were delineated between the fifth and sixth geoelectric layers, having an apparent resistivity above 1000Ωm, with the highest thick of 69.0m at a depth of 144.0m. Longitudinal Conductance, Hydraulic Conductivity, Transmissivity and Product Conductance range are as followings for the aquifers; 1.720 – 127.000 x 10-3Ω-1, 15.90 – 188.79m/day, 1093.3 – 1097.1m2/day and 2.590 – 252.50 x 10-3 respectively. Inferring from our hydraulic parameters, all the aquiferous zones have very high designation, wwithdrawal of great regional importance of groundwater supply potential and practically noncorrosive, soil corrosivity. 40% percentage of the aquiferous units have very good protective capacity, while for excellent and good protective capacity of the study are is 30%. All the VES points are said to be a very viable potential for safe source for groundwater exploration.

Estimates of aquifer geo-hydraulic and vulnerability characteristics of Imo State and environs, Southeastern Nigeria, using electrical conductivity data.

Two hundred and twenty-six vertical electrical sounding (VES) data were acquired across the study area that has six geologic formations for the purpose of evaluating the geo-hydraulic potentials and the protective capacity of the aquifers of the study area. Schlumberger array was adopted for data acquisition using the ABEM™ Terrameter SAS 4000. Results of the study revealed four to six geo-electric layers. A variety of geo-electric curve types were identified in the study area with the KK curve type being dominant. The aquifer zones lie between the third and sixth layers with their resistivity values ranging from 101 to 8900Ωm with a mean value of 1799Ωm. Estimates of the aquifer hydraulic characteristics using the new set of model equations based on conductivity data revealed hydraulic conductivity range of 0.925 and 13.42m/day while transmissivity ranged between 16.0 and 887m2/day. These findings showed that groundwater potential is high in Benin Formation, moderate in Nsukka and Ajali Formations, and generally poor within Ogwashi and Imo Shale Formations. Aquifer vulnerability studies revealed that the values of the integrated electrical conductivity (IEC) of the study area ranged between 28.4 and 2202mS with a mean value of 403mS. Results of the IEC revealed that the aquifer protective capacity of most parts of the study area were extremely poor (86.2%) with percolation period of several months while only 1.8% of the study area are fairly good. The aquifers of the study area may therefore be vulnerable to contamination from anthropogenic sources, and adequate aquifer protective strategies are therefore recommended.

The Socio-economic Factors Affecting Animal Breeding in Urban Households

The objective of this research is to investigate the socio-economic conditions of households who have animal production gardens. The questionnaire was used to collect data. The questionnaire concentrated on collecting data about animal breeding patters, the extent of these animals in these gardens. The sample was distributed on six stratified layers each layer represent a pattern of household income except the sixth layers which represents household gardens suburban areas. The results showed that households concentrate on animal breeding in their gardens. The type of animal breeding depends on the location of layers and laws, which regulate this process. In suburban areas, all kinds of animal were allowed to breed in household gardens. The production attained of animal breeding was very considerable and can be considered as part of household income.

Estimation of Hydraulic Parameters from Vertical Electrical Resistivity Sounding

This study presents the assessment of the groundwater potential in Iyesi, Ota, southwestern Nigeria. Thirty (30) vertical electrical soundings (VESs) were conducted using Schlumberger array with a maximum half-current electrode spacing \((AB/2)\) of 420 m. The apparent resistivity data observed were interpreted first by partial curve matching and then by computer iteration technique using WinResist program. Eight eoelectric layers were denoted as top soil (sandy clay), lateritic clay, silty clay, silty sand, mudstone, medium grain sand, coarse sand and clay mud were delineated. The sixth (medium grain sand) and seventh (coarse sand) layers delineated form the aquifer unit with the overlying mudstone (fifth layer) serving as the confining bed. The geoelectrical and hydrogeological characteristics of the delineated aquifer in the study area was evaluated. The study shows that the aquifer is highly productive and consequently a good groundwater potential. The litho-facies of the aquifer units are well sorted and graded; this accounts for the observed decrease in the model resistivity with depth and thus, increasing porosity with depth in the aquifer unit.

Vacancies in the C(1 0 0)-(2 × 1) diamond surface layers

Our study provides the results of quantum-chemical calculations of the vacancy defect states on a clean and hydrogenated diamond surface C(100)-(2×1) with their positions varying in the first to sixth surface layers. It was found that the most stable defect is the monovacancy in the third layer under the top bilayer dimer row of the clean surface. The formation energy for this vacancy is 0.55eV. In the hydrogenated surface, the vacancy in the third layer becomes metastable, the ground state is the vacancy in the topmost surface layer. It is shown that a vacancy in the third layer does not lead to further spontaneous graphitization of the surface.

Enhanced oscillatory rectification and negative differential resistance in pentamantane diamondoid-cumulene systems.

We propose a new functionality for diamondoids in nanoelectronics. Based on the nonequilibrium Green's function formalism and density functional theory, we reveal that when attached to gold electrodes, the pentamantane-cumulene molecular junction exhibits large and oscillatory rectification and negative differential resistance (NDR) - depending on the number of carbon atoms in cumulene (Cn). When n is odd rectification is greatly enhanced where the rectification ratio can reach ∼180 and a large negative differential resistance peak current of ∼3 μA. This oscillatory behavior is well rationalised in terms of the occupancy of the carbon 2p states in Cn. Interestingly, different layers of C atoms in the pentamantane molecule have different contributions to transmission. The first and third layers of C atoms in pentamantane have a slight contribution to rectification, and the fifth and sixth layers have a stronger contribution to both rectification and NDR. Thus, our results suggest potential avenues for controlling their functions by chemically manipulating various parts of the diamondoid molecule, thus extending the applications of diamondoids in nanoscale integrated circuits.

A class of type-2 fuzzy neural networks for nonlinear dynamical system identification

This paper presents the ability of the interval type-2 Takagi–Sugeno–Kang fuzzy neural networks (IT2-TSK-FNN) for nonlinear dynamical system identification. The proposed IT2-TSK-FNN has seven layers. The first two layers consist of type-2 fuzzy neurons with uncertainty in the mean of Gaussian membership functions. Third layer is rule layer. Type-reduction is done in fourth layer. In the fifth, sixth, and seventh layers, consequent left–right firing points, two end points, and output are evaluated, respectively. In this paper, gradient descent with adaptive learning rate backpropagation is used in learning phase. IT2-TSK-FNN is used for the identification of three nonlinear systems, and then results are compared with adaptive-network-based fuzzy inference system (ANFIS).

Hydrogeophysical study for additional groundwater supplies in El Heiz Area, Southern part of El Bahariya Oasis, Western Desert, Egypt

El Bahariya Oasis is a part of the great groundwater reservoir of the Western Desert of Egypt. The different stratigraphic units, the water-bearing zones, aquifer potentiality conditions, and the favorable locations for drilling new wells were evaluated by carrying out 24 Schlumberger vertical electrical soundings (VESs), along with the data of some wells drilled in the near vicinity of the measuring sites. The results of the interpreted field data revealed the presence of ten distinctive subsurface geoelectric layers; a thin surface, dry loose sand and gravel, sandy clay and shale interclations, saturated coarse sand layer, shale and clay, and saturated fine sandstone and saturated coarse sandstone. The aquifer is a multilayer aquifer with different thicknesses represented by the fourth, sixth, eighth, and tenth geoelectric layers. Results also revealed that the thicknesses of the water-bearing horizons increase towards the east direction, consequently the aquifer potentiality increases. Therefore, the best production well locations are in that direction. Depth to water starts from 40 m at VES no. 14 and increases gradually toward the east to reach 66 m at VES no. 5. Hydrogeochemical analysis of two groundwater samples taken from Ein El Ezza and well no. 2 showed that groundwater in the study area is suitable for agricultural purposes but not for human consumption due to the high iron content. Recommendations concerning site selection for drilling new productive groundwater wells are given.

Atomic diffusion in the Fe [0 0 1] ∑ = 5 (3 1 0) and (2 1 0) symmetric tilt grain boundary

Both the formation and diffusion activation energies of single vacancy migrating intra-layer and inter-layer near the Fe [001] Σ=5 (310) and (210) symmetric tilt grain boundaries have been calculated by using the MAEAM and a MD method. From energy minimization, the vacancy concentration in the second layer is higher than the one in the other layers for both (310) and (210) STGBs. By the diffusion activation energies of the vacancies migrating intra-layer and inter-layer, the vacancies located from the first to the eighth layers of (310) STGB as well as the ones located from the first to the tenth layers of (210) STGB are favorably migrated to the second layer. Thus there is a vacancy aggregation tendency to the second layer near the grain boundary. For the vacancy migrating intra-layer and inter-layer, the influences of the grain boundary are respectively as far as to the fifth and eighth layers for (310) STGB as well as to the sixth and tenth layers for (210) STGB.

Application of linear schlumberger configuration in delineation of formation strata and groundwater distribution in Ifon Ondo State, Nigeria

Linear Schlumberger configuration was employed to delineate the formation strata and groundwater distribution in Ifon Edo State, Nigeria with a view to identifying suitable sites for sitting viable boreholes for long term supply of potable water in the town and nearby communities. Ten vertical electrical soundings (VES) were made using Schlumberger array. Six soundings were made along Orin-Oyih river road and four around the quarry. The obtained field data were subjected to analysis and interpretation by conventional curve matching and computer iteration techniques, “the Resist” The results reveal that stations exhibit A, H and KH curve types mainly. Also sites along the river road have their fifth and sixth layers consisting of medium to coarse grain and gravely sand which is indicative of high water bearing media (aquifer) within 30 - 25 m while sites around the quarry consist of rocks that are far depth with no distinct aquifer. Moreover, while most sites along Orin-Oyih river road have formations of relatively high resistivities, the formations of sites very close to the river and around the quarry exhibit low resistivities. Key words: Schlumberger, Ifon, formation, computer, iteration, aquifer.

Eggshell Pigmentation Study in Blue-shelled and White-shelled Ducks

This study attempted to clarify the difference in eggshell pigmentation between blue-shelled ducks (BSD) and white-shelled ducks (WSD). The eggshell pigmentation deposition process is discussed. Ultraviolet spectro-photometer and HPLC were used to determine the biliverdin concentration in the shell gland, uterus liquid and eggshell at 6, 12, 18, 20, 23.5 h post-oviposition. The biliverdin concentration in the eggshell and uterus fluid showed significant differences between BSD and WSD, but not in the shell gland. The heme oxygenase activity in the shell gland of both kinds of ducks remained mostly constant during the ovulatory cycle with no variation. The assay of exogenous biliverdin injection into the shell gland antrum in the WSD indicated that exogenous biliverdin could be deposited continuously into the eggshell until the source was exhausted. A layer-by-layer dissolution assay was used to examine the eggshell pigment deposition process. The biliverdin concentration in the first to sixth layers of the eggshell in the BSD was significantly higher than that in the white-shelled counterpart. The blue pigment concentration increased persistently from the 6 th layer to the 1 st layer. The BSD eggshells did not accumulate a large quantity of biliverdin in the most external layer. They tended to increase the deposition layer by layer. Our results demonstrated that different BSD and WSD eggshell colors were influenced by the amount of biliverdin in the uterus fluid and not determined by the amount of biliverdin in the shell gland. This implies the existence of a mechanism that controls biliverdin transportation from the shell gland into the uterus fluid, thereby playing a key role in regulating duck eggshell color.