Stages Of Closure Research Articles

Early embryonic development of green crucian carp Carassius auratus indigentiaus subsp. nov.

The early embryonic development of the green crucian carp (Carassius auratus indigentiaus subsp. nov.) was observed to study its timing and characteristics. The fertilized eggs are round, slightly yellow, and viscous demersal. The egg diameter after water swelling was 1.47 ± 0.04 mm. Embryonic development can be divided into eight stages according to its major characteristics: blastoderm formation, mitotic, blastula, gastrula, neurula, blastopore closure, organogenetic and hatching stages. Under a water temperature of 24 ± 1 °C, salinity of 35 ± 1, and pH of 7.4 ± 0.5, the blastoderm began to form 35 min after fertilization. It entered the mitotic stage at 55 min, blastula stage at 220 min, gastrula stage at 460 min, neurula stage at 675 min, blastopore closure stage at 700 min, organogenetic stage at 900 min and hatching stage at 3390 min. The total length of newly hatched larvae was 4.07 ± 0.35 mm. Regression models of growth characteristics were obtained. The full-length growth rate was fastest from 15 to 26 days, with an average of 0.396 mm/day. Compared with other cyprinid fishes, green crucian carp exhibited some distinct characteristics in certain stages of embryonic development. The eye primordium developed before the sarcomere, and the heart rate was relatively high before the member stage. Yolk fluctuation was observed during the multi-cell phase of embryonic development. The sarcomere formed after the eye primordium. The heart rate in the hatching phase was 136 beats/min. This study provides a reference for embryonic development in green crucian carp, which will assist its large-scale cultivation.

Study on the Characteristics of Granite in Different Stress Stages through a Cyclic Loading Experiment

The deformation and failure process of rocks is a gradual process. The purpose of this study was to examine the characteristics of rocks in different stages through a cyclic loading experiment. The experiment was carried out based on the MTS815 rock mechanics test system combined with acoustic emission monitoring equipment to study the typical characteristics of two kinds of granite in the stages of crack closure, linear elastic deformation, crack initiation and stable crack growth, along with crack damage and unstable crack growth. The results showed that there were significant differences in the characteristics of the strain response, energy evolution, and acoustic emission of the two granites in the different stages. Although the microstructure and mineral elements of the two granites are different, the characteristics of the two granites in the same stage were similar, indicating that the stage characteristics of brittle rocks in the failure process may be widespread and have significant similarities.

Lateral deformation and acoustic emission characteristics of dam bedrock under various river flow scouring rates

To investigate the lateral deformation characteristics of dam bedrock scoured by river flow environments, standard specimens were prepared using cored sandstone from the barrage bedrock at the Sanhekou Water Conservancy Dam. The mechanical parameters, microstructure, and mineral fractions of the sandstones were analyzed after water scouring at five different rates (0, 200, 400, 600, and 800 mm⋅s−1) for 49 days. Scanning electron microscopy (SEM), electron energy spectroscopy (EDS), and X-ray diffraction (XRD) techniques were employed to track the changes. Laboratory tests including uniaxial compression, acoustic emission (AE), and digital image correlation (DIC) were conducted to elucidate the deformation damage mechanism of the scoured sandstones. The results indicate the following: (1) During the crack closure and compaction stage, the deformation of the rock samples primarily involves axial compression with minimal lateral deformation. However, as the crack propagates unstably and expands after the peak load, the lateral strain of the specimens accelerates. The lateral-axial ratio of the samples remains relatively low during the initial scouring period but increases rapidly after the first drop in axial stress until the end of the test. Higher scouring rates and longer durations weaken the strength and exacerbate the deformation of the sandstone. Under a flow rate of 800 mm⋅s−1, the elastic modulus decreases by 45.67%, while Poisson's ratio increases by 73.67%. (2) The acoustic emission process exhibits distinct phases, including a calm phase, growth phase, and rapid rise phase. As the flow rate increases, the internal crack types in the sandstone transition from shear cracks to tensile cracks, corresponding to the shift from shear failure to cleavage failure. The sandstone's damage variables show progressive abrupt changes under flow rates of 0, 200, and 400 mm⋅s−1, while segmented growth is observed under flow rates of 600 and 800 mm⋅s−1. (3) After absorbing water in a dynamic water environment, the interparticle cementation capacity of the sandstone weakens due to softening, water-rock interactions, and swelling reactions of clay minerals. The overall structure becomes destabilized, ultimately leading to failure through deformation. These findings provide a basis for predicting destruction and analyzing the stability of rock masses during water absorption and expansion deformation under dynamic water conditions.

The geochemical processes affecting the mobility of Cu, Pb, Zn during phytostabilization on sulfidic mine tailings revealed by a greenhouse study

Sulfidic mine tailings have the potential to release toxic metals into the surrounding environment. Phytostabilization can stabilize these toxic metals in the rhizosphere, providing a sustainable method for mine reclamation. However, previous research has not examined the inorganic geochemical processes in the rhizosphere that are significant for controlling acid mine drainage. Therefore, a greenhouse study was conducted to explore the geochemical processes affecting the mobility of Cu, Pb, and Zn through the establishment of phytostabilization on sulfidic mine tailings. The mineralogy of substrates before and after experiments and the changes in metal concentrations and pH of the drainage were analyzed. The results showed that at the end of the experiments, pH of pot substrates with plants became acidic (pH ranging from 2.59 to 3.77), the concentrations of Cu, Pb, and Zn in the drainage increased (up to 20.14 mg/L of Cu, 2.28 mg/L of Pb, and 3199.87 mg/L of Zn), leading to the generation of acid mine drainage. It was concluded that, in addition to the sulfide oxidation, two other acidification processes played a role: the decomposition of organic matter and the release of roots exudates, in decreasing pH and increasing metal concentrations in the drainage from amended tailings. The acidity in the rhizosphere was neutralized sequentially through the following geochemical processes: (1) dissolution of carbonates, (2) dissolution of Al&Fe (oxy)hydroxide, and (3) silicates weathering. The long-term reliability of phytostabilization can be achieved by re-applying amendments to initiate these neutralization processes. This research has filled the research gap regarding the geochemical mechanisms controlling the migration of metals in the rhizosphere during phytostabilization with two grass species (Pascopyrum and Lolium multiflorum). It provides a valuable reference for designers and engineers when considering metal immobilization in sulfidic mine tailings through the technique of phytostabilization during mine reclamation and closure stage.

ANALISIS PERANAN GURU DALAM MENINGKATKAN PRESTASI BELAJAR SISWA KELAS 2 SD N KARANGREJO 02 SEMARANG

A teacher is a beacon of knowledge and learning. The characteristics of an ideal teacher include both competence and character. An ideal teacher is someone who can impart patience and perseverance. Based on the observations conducted by the researcher during the Field Experience I (PPL I) activities, it was found that the second-grade students at SD Negeri Karangrejo 02 in Semarang still had a low level of academic achievement. This was evident from the evaluation results of the first cycle of teaching practice conducted by the researcher, which indicated that the teaching process in the classroom had not been entirely successful, as reflected in the unstable evaluation scores of the students. This research utilized a qualitative method and was conducted at SD Negeri Karangrejo 02 in Semarang. The research sample consisted of second-grade students at SD Negeri Karangrejo 02 in Semarang. Data collection was carried out through observation and interviews with the second-grade teacher at SD Negeri Karangrejo 02 in Semarang. The data analysis involved data reduction, data display, and conclusion drawing. The results of this research indicate that the role of the teacher in enhancing student achievement includes the stages of opening, core activities, and closure. Additionally, the teacher also plays the roles of motivator, instructor, mentor, and evaluator.

Assessment of Stakeholder Involvement and Borehole Water Projects Delivery in Kogi West Senatorial District, Nigeria

There is huge challenges in the supply of clean water for household consumption in many countries, in particular, Nigeria. Kogi West Senatorial District (KWSD) has witnessed more borehole projects in Nigeria but the challenge of clean water still persists. This has necessitated more research into the field of water resources to combat such challenges in line with the sustainable development goals (SDGs). This study assessed the effects of stakeholders’ involvement in KWSD, Nigeria, with a view to improving the delivery of borehole water projects in the study area. Data were collected through a structured questionnaire from 267 stakeholders comprising Lower Niger River Basin Development Authority (LNRBDA) staff, community leaders and community members that were selected using simple random sampling technique. The study objective was assessed with inferential statistics (Partial Least Square in Structural Equation Modelling). The results disclose the direct path coefficients for Initiation stage (bIS), Planning stage (bPS), Execution stage (“bES”), Monitoring and closure stage (bMS), Post construction stage (bPCS), Budget (cBG), Time Delivery (cTD) and Stakeholder’s Satisfaction (cSS). The results illustrated positives and significant relationship with bES -> cBG (β = 0.422, t = 5.708), bES -> cSS (β = 0.495, t = 6.366), bES -> cTD (β = 0.493, t = 7.422), bMS -> cBG (β = 0.164, t = 2.643), bPCS -> cTD (β = 0.257, t = 5.7084.440), and negative significant relationship with bMS -> cTD (β = -0.184, t = 2.547) and bPS -> cSS (β = - 0.182, t = 2.586). The study concludes that stakeholders’ involvement is a strong predictor of viable Borehole water projects delivery in the study area.

The biomechanics of chewing and suckling in the infant: A potential mechanism for physiologic metopic suture closure.

Craniosynostosis is a condition with neurologic and aesthetic sequelae requiring invasive surgery. Understanding its pathobiology requires familiarity with the processes underlying physiologic suture closure. Animal studies have shown that cyclical strain from chewing and suckling influences the closure of cranial vault sutures, especially the metopic, an important locus of craniosynostosis. However, there are no human data correlating strain patterns during chewing and suckling with the physiologically early closure pattern of the metopic suture. Furthermore, differences in craniofacial morphology make it challenging to directly extrapolate animal findings to humans. Eight finite-element analysis (FEA) models were built from craniofacial computer tomography (CT) scans at varying stages of metopic suture closure, including two with isolated non-syndromic metopic craniosynostosis. Muscle forces acting on the cranium during chewing and suckling were simulated using subject-specific jaw muscle cross-sectional areas. Chewing and suckling induced tension at the metopic and sagittal sutures, and compressed the coronal, lambdoid, and squamous sutures. Relative to other cranial vault sutures, the metopic suture experienced larger magnitudes of axial strain across the suture and a lower magnitude of shear strain. Strain across the metopic suture decreased during suture closure, but other sutures were unaffected. Strain patterns along the metopic suture mirrored the anterior to posterior sequence of closure: strain magnitudes were highest at the glabella and decreased posteriorly, with minima at the nasion and the anterior fontanelle. In models of physiologic suture closure, increased degree of metopic suture closure correlated with higher maximum principal strains across the frontal bone and mid-face, a strain regime not observed in models of severe metopic craniosynostosis. In summary, our work provides human evidence that bone strain patterns from chewing and suckling correlate with the physiologically early closure pattern of the metopic suture, and that deviations from physiologic strain regimes may contribute to clinically observed craniofacial dysmorphism.

Depositional cycles in a rift lacustrine basin linked with tectonics, climate, and source rocks and reservoirs development: Lower Cretaceous in Naiman sag, Songliao Basin, Inner Monglia, Northeast China

In order to improve understanding of the depositional evolution processes in rift lacustrine basins in Northeast China under Early Cretaceous greenhouse climate fluctuations, the roles of tectonics and climate along with the development of source rocks and reservoirs in the evolution of continental rift lacustrine basins in Naiman sag, Songliao Basin, Inner Monglia, were studied. Based on the detailed facies analysis of the subsurface boreholes, eight facies were identified in the Lower Cretaceous strata of Naiman sag and were grouped into three facies associations, namely fan delta, littoral to sublittoral lacustrine, and deep lacustrine. Based on the depositional characteristics, in combination with lacustrine evaporites and carbonate deposition, organic matter preservation, and lake depth, the Lower Cretaceous strata of the Naiman sag was further subdivided into four lake stages, namely initial formation of lake (Stage 1), sediment-fill shallow lake (Stage 2), rising to a high lake (Stage 3), and lake closure (Stage 4), respectively. The lake evolution in the Naiman sag was driven by both tectonics and climate changes. Fault-driven subsidence was likely contributed to episodic changes in accommodation and lake formation (Stage 1), expansion (Stage 3) and shrinkage (Stage 4). A combination of regional and global climate overprint controlled the sedimentary characteristics, depositional trends, and sediment and water supply. The global climate of ocean anoxic events 1a and 1b (OAE1a and OAE1b) may have effects on anoxic conditions of Stages 1 and 3, respectively. During regional climate changes between arid, hot and humid, seasonal climate tended to form evaporite deposits and multiple layers of oil shale deposits in Stage 1. During the more humid regional climate, steady runoff tended to form fan delta deposits prograding into the lake basin in Stages 2 and 4 and thick-bedded oil shale deposits in Stage 3. The development of source rocks is linked with lake formation and expansion stages (Stages 1 and 3), and the source rocks are mainly preserved in the deep lacustrine and littoral to sublittoral lacustrine environment. The development of reservoirs is associated with lake formation, sediment-fill, and shrinkage stages (Stages 1, 2, and 4), and the reservoirs are mainly preserved in the fan delta environment.

Quantitative investigation on localized deformation process of rocks by uniaxial test and digital image correlation

Determining the localized deformation mechanism is of vital importance to understand the failure processes of geomaterials in practical engineering. In this study, uniaxial monotonic and cyclic loading tests of slate samples were conducted and the failure processes were recorded by using the AE system and digital image correlation (DIC). The results show that the deformation field variance increases significantly in the initiation of the macro-scale failure stage. Under cyclic loading, the shape of the stress-variance hysteresis curve varies with increasing upper limit stress, and four types of stress-variance hysteresis curves were revealed. Increasing lag time of variance indicates gradual accumulation of damage to the sample. The comprehensive analysis of the evolution process of damage variables defined by cumulative AE counts and variance reveals that the rock failure process can be divided into crack closure stage, initial damage stage, stable development stage, accelerated development stage and failure stage. By proposing the differentiation rate, it is found that there are apparent failure precursor points under monotonic and cyclic loading.

Potential Role of AGR2 for Mammalian Skin Wound Healing.

The limited ability of mammals to regenerate has garnered significant attention, particularly in regard to skin wound healing (WH), which is a critical step for regeneration. In human adults, skin WH results in the formation of scars following injury or trauma, regardless of severity. This differs significantly from the scarless WH observed in the fetal skin of mammals or anamniotes. This review investigates the role of molecular players involved in scarless WH, which are lost or repressed in adult mammalian WH systems. Specifically, we analyze the physiological role of Anterior Gradient (AGR) family proteins at different stages of the WH regulatory network. AGR is activated in the regeneration of lower vertebrates at the stage of wound closure and, accordingly, is important for WH. Mammalian AGR2 is expressed during scarless WH in embryonic skin, while in adults, the activity of this gene is normally inhibited and is observed only in the mucous epithelium of the digestive tract, which is capable of full regeneration. The combination of AGR2 unique potencies in postnatal mammals makes it possible to consider it as a promising candidate for enhancing WH processes.

Comparative study of the efficacy of lens extraction and laser peripheral iridotomy in primary anterior chamber angle closure

PURPOSE. To compare the anatomical and functional effectiveness of lensectomy (LE) and laser peripheral iridotomy (LPI) in patients with primary anterior chamber angle closure.METHODS. This prospective study included 120 patients aged 41 to 80 years (60 eyes — primary angle closure (PAC), 30 — primary angle closure suspects (PACs), 30 eyes — without ophthalmic pathology). 30 PAC eyes were treated using LE with intraocular lens implantation, and 30 eyes with LPI. All subjects underwent swept source optical coherence tomography (SS-OCT). The following parameters were analyzed: spherical equivalent (SE), uncorrected and corrected distance visual acuity, intraocular pressure (IOP), Shaffer grade of angle opening, lens opacity, goniosyne chiae, choroidal thickness in the macular region, axial length (AL) of the eye, anterior chamber depth (ACD), lens vault (LV), iris curvature (ICurv), iris thickness at 750 µm from scleral spur (IT750), angle opening distance (AOD500, AOD750), iridotrabecular space area (TISA500, TISA750). Along with standard descriptive statistics methods, machine learning methods were used, including Data Driven Soft Independent Modelling of Class Analogies (DD-SIMCA).RESULTS. Every third eye with PAC had reached control group values after LE (DD-SIMCA specificity 0.67), which was not the case after LPI (DD-SIMCA specificity 1.0) with the probability of getting into the control group estimated as 0.01. After LE, all parameters of the anterior chamber angle did not significantly differ from the norm (p>0.05 for all), while ACD, ICurv even exceeded the norm (p=0.000). After LPI, there was a deepening of the ACD (from 2.34±0.28 mm to 2.36±0.280 mm, p=0.000) and a decrease in LV (from 0.864±0.120 µm to 0.843±0.110 µm, p=0.000), however, the result comparable to control was achieved only in ICurv (p=1.000). After LE in PAC, all parameters, including uncorrected visual acuity, SE, ACD, LV, iris profile, Shaffer grade of angle opening, and AOD500, AOD750, TISA500, TISA750 parameters in the superior and inferior sectors had advantages over those in PACs without treatment (p<0.05). After LPI, an improvement in a number of pa rameters was also achieved compared to LPI: ICurv, Shaffer grade of angle opening, AOD500, AOD750, TISA500, TISA750 in the superior sectors and AOD500 in the inferior sector (p><0.05).CONCLUSION. The effectiveness of LE in PAC is higher than LPI due to the better postoperative anterior chamber topography and lower IOP. Both treatments, especially LE, improve these parameters compared to PACs. Lens extraction is the treatment of choice at the early stages of primary angle closure.

Time-Frequency Characteristics and Evolution Law of Acoustic Emission Signals during the Deformation and Failure of Deformed Coal.

The research on the time-frequency characteristics and evolution law of acoustic emission (AE) signals during deformed coal failure is more conducive to understand the damage mechanism of coal. In this study, the experiments of AE monitoring during the intact and deformed coal failure were first conducted under loading axial stress and unloading confining stress conditions. Based on the evolution characteristics of volume strain and AE event rate, the damage process of coal was divided into three stages: nonfracture development stage, stable development stage of fracture, and unstable development stage of fracture. The distribution and evolution of AE waveform time-frequency properties under different damage processes were then analyzed and discussed. Besides, the evolution of the average value of different time-frequency parameters per 200 s for the intact coal and per 25 s for the deformed coal was discussed. The results show that the amplitude of most AE events stabilizes in 40-50 dB during the intact and deformed coal failure. The average amplitude of the deformed coal has an approximate positive correlation with the loading stress. The percentage of AE events with longer duration and rise time increases suddenly before the peak stress for the intact coal and after the peak stress for the deformed coal, which corresponds to the abrupt increase property of the average duration and rise time. For the frequency properties, the peak frequency and frequency centroid of the intact coal are distributed within 50-125 and 75-150 kHz, with those of the deformed coal located within 20-120 and 80-130 kHz, respectively. The average peak frequency and frequency centroid of the intact coal show an upward trend except for the initial fracture closure stage, while the average peak frequency and average frequency centroid of the deformed coal present a downward trend before the peak stress and have a smaller growth after the peak stress. According to the above-mentioned analysis, the sudden increase of the average duration and rise time, the lower average peak frequency, and the lower frequency centroid can be regarded as the precursor for the instability and failure of deformed coal. This research can provide a new idea and theoretical guidance for the early warning of outbursts.

Spiderplasty and Bow-tie Tension Relieving Suture Techniques for Large Skin Defects in Dogs

Background: In veterinary practice, cutaneous injuries are a very common occurrence. Various methods have been employed to close large skin defects like skin graft or flap often associated with relatively more complex surgical procedures. Use of tension relieving suture techniques like spider plasty and bow tie technique allow the mobilization of adjacent local tissue to cover large cutaneous defects which was thus utilised in the study. Methods: Twelve dogs brought to the Madras Veterinary College Teaching Hospital, Chennai,TANUVAS with large diameter open wounds were selected for the study. Irrespective of the stage of closure the two tension relieving suture techniques, i.e. Spiderplasty and Bow-tie, were performed for closure of the large wounds. The preoperative and postoperative wounds assessment were performed through subjective evaluation, planimetry, bacteriological examination and histopathological evaluation. Result: The Spiderplasty technique was more time consuming, required more surgical expertise and had slightly lower cost efficiency ratio. It could however be better utilised to close wounds located in confined anatomical areas, as compared to the Bow-tie procedure which was limited by its requirement to resect 36% of adjacent normal tissue.

Theoretical and experimental study on the long-term conductivity of heterogeneous artificial fractures in tight reservoirs

Volume fracturing technology is used to achieve economic recovery of crude oil in tight reservoirs. Then, the fluid flows into the wellbore through artificial fractures in the fractured zone, and the reservoir permeability is improved. Therefore, the study of the conductivity of artificial fractures is the key link for the fracturing development of tight reservoirs. Presently, experimental and theoretical studies on conductivity are based on a homogeneous model, which cannot reflect the nonuniform distribution of proppants in actual artificial fractures. Experiments on the long-term nonuniform sand spreading of artificial fractures in tight reservoirs are carried out in this paper with different influencing factors. Then, the influences of the matrix of proppant performance, proppant concentration, reservoir lithology, reservoir permeability and closure stress on the long-term conductivity of artificial fractures are clarified. The calculation model of the long-term conductivity of heterogeneous artificial fractures considering the reservoir characteristics, fracturing technology and reservoir characteristics is established based on the conductivity loss mechanism. Finally, the conductivity model is applied to the 7th tight reservoir block in the Ordos Basin, and the productivity prediction results are compared. The results show that the average loss of the conductivity of the heterogeneous artificial fractures is 26.6% relative to the initial state, and the loss of the conductivity is mainly at the initial stage of closure, accounting for approximately 90% at the condition of 60MPa confining pressure. The calculation accuracy of the theoretical nonuniform conductivity model is 92.2%, which can describe the continuous depression of the artificial fracture conductivity after introduction into the tight reservoir numerical simulation.

An Enhanced 3D Model of Intravascular Lymphatic Valves to Assess Leaflet Apposition and Transvalvular Differences in Wall Distensibility

Lymphatic valves operate in a fluid-dynamically viscous environment that has little in common with that of cardiac valves, and accordingly have a different, axially lengthened, shape. A previously developed 3D fluid/structure interaction model of a lymphatic valve was extended to allow the simulation of stages of valve closure after the leaflets come together. This required that the numerical leaflet be prevented from passing into space occupied by the similar other leaflet. The resulting large deflections of the leaflet and lesser deflections of the rest of the valve were mapped as functions of the transvalvular pressure. In a second new development, the model was reconstructed to allow the vessel wall to have different material properties on either side of where the valve leaflet inserts into the wall. As part of this, a new pre-processing scheme was devised which allows easier construction of models with modified valve dimensions, and techniques for successfully interfacing the CAD software to the FE software are described. A two-fold change in wall properties either side of the leaflet made relatively little difference to valve operation apart from affecting the degree of sinus distension during valve closure. However, the numerically permitted strains were modest (<14%), and did not allow examination of the large-scale highly nonlinear elastic properties exhibited by real lymphatic vessels. A small series of murine popliteal, mesenteric, and inguinal-axillary lymphatic vessel segments containing a valve were experimentally investigated ex vivo. The pressure-diameter curves measured just upstream and just downstream of the valve were parameterised by computing the difference in tubular distensibility at three values of transmural pressure. In the popliteal and mesenteric segments, it was found that the distensibility was usually greater just downstream, i.e., in the sinus region, than upstream, at low and intermediate transmural pressure. However, there was wide variation in the extent of difference, and possible reasons for this are discussed.

Training model for the fetal myelomeningocele correction with multiportal endoscopic technique.

The recent history of myelomeningocele has shown that treatment during the fetal life may reduce the risk of developing hydrocephalus in individuals by approximately 50%. Thus, a significant advancement involves fetal surgery performed through an endoscopic technique in which portals are placed to introduce the forceps and laparoscopic instruments. However, the development of this technique requires training; therefore, this study aimed to develop a training model for fetal myelomeningocele repair technique with multi-portal endoscopy. Two stages of endoscopic technique development were performed. The first stage consisted of exercises in order to familiarize the surgeon with 2D-vision endoscopic surgery, associated with the application of exercises focused on surgical skills, such as the development of laparoscopic knots in a synthetic model. The second stage involved the creation and application of the stages of myelomeningocele closure with a non-living animal model consisting of a chicken breast to simulate the myelomeningocele and a basketball to simulate the gravid uterus, in which perforations were made to introduce vascular introducers (portals) that, as in vivo, are used as portals (trocars) for the introduction of laparoscopic instruments. Overall, two different scenarios with three portals and two portals were tested. In three-portal simulator, the triangular apex trocar was used for the introduction of 4-mm 0° or 30° optics or even Minop type neurodoscope (Aesculap®, Germany) that was operated by the assistant surgeon; the other two portals are used for the introduction of laparoscopic instruments. Thus, the surgeon is able to perform maneuvers bimanually since dissection to laparoscopic sutures. In two-portal simulator, the surgeon and assistant stay side by side and one of the portals is used for the optic and the other for the laparoscopic instruments. There is no possibility of bimanual dissection in this method. Realistic simulation models for endoscopic fetal surgery for myelomeningocele correction are easily performed and help develop the necessary skills for fetal surgery teams.

Magmatic evolution of the Calc-alkaline Middle Jurassic igneous rocks in the eastern pontides, NE Turkey: insights from geochemistry, whole-rock Sr-Nd-Pb, in situ zircon Lu-Hf isotopes, and U-Pb geochronology

ABSTRACT The Eastern Pontides in NE Turkey hosts a very limited number of plutonic rocks from the Jurassic period. Here we submit new geochemical, Sr-Nd-Pb and zircon Lu-Hf isotope data, and zircon U-Pb ages for plutonic rocks in this region. Zircon U-Pb dating for the Alemdar and Işıkdere plutons yielded an age of 175–170 Ma (Middle Jurassic). The Alemdar and Işıkdere plutons have I-type, medium to high-K calc-alkaline series, and metaluminous to slightly peraluminous characteristics. On PM-normalized diagrams, the plutons are enriched in large-ion lithophile elements (LILEs) with pronounced depletion of high field strength elements (HFSEs, Ta, Nb, Ti). Chondrite-normalized plots for the plutons show variable enrichment in light rare earth elements (LREEs) with depletion of heavy rare earth elements (HREEs). The rocks of the Alemdar Pluton have homogeneous ISr values (0.70585 to 0.70673), low εNd(i) values (−3.9 to −1.6), pozitif εHf(i) values (+3.3 to +9.1), and Hf single-stage model ages (563–712 Ma), whereas those of Işıkdere have high ISr values (0.70666 to 0.70673), low εNd(i) values (−3.9 to −3.8), εHf(i) values (−3.1 to +1.1), and Hf single-stage model ages (791–969 Ma). These values imply that they have different sources. These results suggest that the magma of the Alemdar was formed by the partial melting of a relatively depleted lithospheric mantle wedge interaction of the OIB-like melts, while those of Işıkdere have derived from the partial melting of an enriched mantle metasomatized by slab-derived sediments and then modified by fractional crystallization and crustal contamination in crustal magma chambers. Considering the available data, we conclude that the studied plutons were related to extensional tectonic events during the Middle Jurassic in response to the roll-back of the Paleotethys oceanic slab in the final stage of oceanic closure. These rocks are an example of the formation of deep subduction products following Early Jurassic subduction.

An Assessment and Comparison of Root Resorption With Two Different Corticotomy Techniques During Anterior Teeth Retraction: A Split Mouth Prospective Clinical Study.

Aim The aim of this prospective split-mouth clinical study is to determine the apical root resorption of anterior teeth in patients with two different methods of corticotomy namely indentation and vertical corticotomy techniques. Methods Sixteen adult patients with bimaxillary protrusion requiring the need for extraction of the first premolars were included in the study. For each patient, the particular method of corticotomy technique was assigned randomly along with the side and the procedure was performed following which retraction forces were applied with the help of a closed coil Niti spring. The root resorption was recorded during the stage of space closure for which two cone beam computed tomography (CBCT) were taken, one before the retraction forces could be applied (T1) and one CBCT (T2) after the space closure had occurred. The apical root resorption was assessed and analyzed both linearly and volumetrically using the CBCT taken at T1 and T2. Results There was root resorption present after the space closure was complete in both the maxillary and mandibular arches. The amount of root resorption that occurred in the indentation technique was slightly lesser as compared to the vertical corticotomy technique. Conclusion Indentation corticotomy cuts for accelerated tooth movement are considered to be a much safer, more effective method, lesser invasive to the surrounding tissues, technique sensitive, and goodregional acceleratory phenomenon (RAP), with a Rapid healing process compared to the vertical corticotomy technique.

Some Thoughts about Infrared Radiation Response Characteristics during Loading of Sandstone Samples

The infrared radiation response characteristics and mechanisms of sandstone samples under uniaxial compression were investigated using infrared thermal imaging and strain measurement techniques. The stress–strain curves were divided into different damage stages (i.e., crack closure, elastic deformation, stable crack growth, unstable crack growth, and post-failure) by the damage thresholds determined using the transverse and vertical strains. Experimental results show that the infrared radiation response characteristics of sandstone include the superposition of different mechanisms, which lead to either temperature increase or decrease. The response mechanisms of infrared radiation vary depending on the damage stage. During crack closure and elastic deformation stage, temperature variations are mainly governed by thermoelastic effects and the nearly adiabatic compression of air in the pore space. In the stable and unstable crack growth phase, the temperature variations are dominated by two reverse acting processes: heat production by frictional sliding and cooling by the expansion of gases in pore spaces. This leads to complex inhomogeneous radiation and consequently temperature distribution at the sample surface with local hotspots.

On the pressure decline analysis for hydraulic fractures in elasto-plastic materials

In this paper the problem of a plane strain hydraulic fracture in elasto-plastic material is analyzed. The analysis is based on Finite Element Method computations of crack propagation and closure to simulate the Mini-Frac calibration test. The basic trends of fracture evolution are identified for both, the propagation and the closure stage in elasto-plastic materials and compared with the results obtained for purely elastic deformation of rock. Pressure decline analysis is conducted to identify the closure stress and leak-off coefficient. The results show that the standard techniques of pressure decline analysis can be adopted also for the case where the fractured material deforms inelastically.