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In a welding process, distortion is inevitable and causes a significant problem. Distortion could be minimized up to a specific limit by controlling the welding parameters. The expansion and contraction of the welding metal and the adjacent base metal during the heating and cooling cycles of the welding process create thermal stresses and angular distortion in a welding joint. The welding parameters determine the geometry of a weld bead. The form of the weld bead is vital in the angular distortion of butt welded plates. This article discusses the influence of some flux-cored arc welding process parameters such as shielding gas flow rate, weaving motion of welding electrodes, and torch angle on bead profile and angular distortion of St 37 steel plates of 10 mm thickness. The angular distortion decreases with the torch angle, but it increases with the gas flow rate. The electrode weaving motion consists of three components: the designed weld width, the vertical motion period in the welding direction, and the lateral motion speed normal to the welding direction. The angular distortion decreases with the weld width and the vertical motion period but decreases with the lateral speed.

Purpose: Dental student’s dental anxiety may negatively affect patient’s attitude towards dental treatment. We evaluated dental anxiety among dental students in different clinical stage of their studies. We assessed the student’s anxiety prior to treating patients. Study design: A cross-sectional study. Fourth to sixth-year dental students completed questionnaires containing: 1) Dental Anxiety Scale (DAS); 2) Dental Fear Survey (DFS); and 3) visual analogue scale questions relating to the student’s anxiety when performing dental treatments in children and adults. Results: 124 dental students completed the questionnaires (mean age, 26.4±3.1 years, 59.7% women). Average DAS in the study population was 7.55±2.15 with similar scores observed across the years. Average DFS score was highest among fourth-year students (1.62±0.65) and lowest among sixth year students (1.36±0.32). DFS scores decreased as the students progressed through the clinical years (p=0.059). The students’ average anxiety scores prior to treating children were significantly higher than the anxiety scores prior to treating adults (3.82±2.42 vs. 2.67±1.9, p

Structural, sedimentological, well and seismic data from the Kura basin show that the geometry of deformation has been largely determined by thick-skin structures occurring along margins of depressions filled with upper Oligocene–lower Miocene Maykop formation, flanked by highs without Maykop record. Thin-skin structures are detached inside the shaly Maykop formation and inside shale horizons of the Sarmatian–Pontian section. The main shortening took part during Sarmatian–Pontian, followed by subordinate shortening during Akchagylian–present. The thick-skin architecture formed first, reactivating pre-existing rift grain on the foreland plate that refused to flex underneath the load of advancing orogens. The thin-skin architecture developed subsequently, deforming thick-skin structures. During the Oligocene–early Miocene, the foreland basin behaved as a flexural basin, reacting by prominent fill asymmetry to Oligocene loading by the advancing Lesser Caucasus and earliest Miocene–early Sarmatian loading by advancing Greater Caucasus. Subsequently, the basin recorded only vertical movements responding to new orogen loading events. Each loading event was recorded by a shift of marine depositional environments northwestwards, up the SE-plunging Kura Valley. Conversely each quiescence period was recorded by their retreat southeastwards, towards the Caspian Sea.

It has been hypothesized that abnormalities in the molecular clock underlie the development of mood disorders, in the direction of higher prevalence in individuals with a reduced flexibility to adapt to important regulations of mood in response to changes in seasons, stress levels, sleep schedules, and time zones. In particular, a T/C change (rs1801260) at the 3111 position of the circadian locomotor output cycles kaput (CLOCK) gene has been explored in psychiatry disorders. This meta-analysis has been undertaken to investigate the association between rs1801260 and both mood disorders and depression severity, shedding light on previous controversial results and providing better power to detect smaller effect sizes. PubMed and ISI databases were searched for studies focused on the association between rs1801260 and mood disorders spectrum. Quality of studies was assessed. We found no association between CLOCK genotypes and mood disorders, even when we separately investigated ethnical homogeneous or unipolar disorder studies. No association was found regarding severity of depression either. The methodological quality of the studies has been found to be medium-high. Our meta-analysis shows no association between rs1801260 and mood disorders (as a complete phenotype) or depression severity and points out the necessity of further research in order to better understand the underlying biological machinery of circadian dysfunction in subjects affected by mood disorders. (Author correspondence: alessandro.serretti@unibo.it) It has been hypothesized that abnormalities in the molecular clock underlie the development of mood disorders, in the direction of higher prevalence in individuals with a reduced flexibility to adapt to important regulations of mood in response to changes in seasons, stress levels, sleep schedules, and time zones. In particular, a TC change (rs1801260) at the 3111 position of the circadian locomotor output cycles kaput (CLOCK) gene has been explored in psychiatry disorders. This meta-analysis has been undertaken to investigate the association between rs1801260 and both mood disorders and depression severity, shedding light on previous controversial results and providing better power to detect smaller effect sizes. PubMed and ISI databases were searched for studies focused on the association between rs1801260 and mood disorders spectrum. Quality of studies was assessed. We found no association between CLOCK genotypes and mood disorders, even when we separately investigated ethnical homogeneous or unipolar disorder studies. No association was found regarding severity of depression either. The methodological quality of the studies has been found to be medium-high. Our meta-analysis shows no association between rs1801260 and mood disorders (as a complete phenotype) or depression severity and points out the necessity of further research in order to better understand the underlying biological machinery of circadian dysfunction in subjects affected by mood disorders. © 2010 Informa UK Ltd.

Composites of calcinated bovine bone derived hydroxyapatite (HA) with 0.5 and 1 wt% Y2O3 were prepared by sintering. Money and time saving feature the production of HA from natural sources. In this study, results of scanning electron microscopy (SEM) and X-ray diffraction analysis aimed to interpret the results of measurements of densification, microhardness, and compression strength of the produced composites. The best mechanical properties were achieved after sintering at 1200°C for compressive strength and 1300°C for microhardness. The results are in a fair agreement with densification measurements and microstructure analysis.

In the chocolate production process, the moisture content of ground cocoa is removed in a spray-drying unit, in which wet cocoa is pumped through a high-pressure pump. Wear occurs in this high-pressure pump, which can cause problems in the system. Originally, valves and beds were made of AISI 316 Ti austenitic stainless steel, and their average wear life was less than 280 h, obviously too short for use in industrial production. The aim of the research reported in this paper was to investigate ways to increase the wear life of these parts. In this respect six different materials were tested. Valves and beds were produced from four different steels and two powder metals. The steel parts were hardened by heat treatment. All the parts were electroplated with CrN or TiN. Wear life tests were carried out, and it was shown that AISI M2 high-speed steel valves and beds gave the longest wear lives.

Sensitivity analysis is the study of a system's response to various disturbances. In this study, disturbances of aquifer parameters are considered. In the simulation of an aquifer the investigator must establish tolerances within which the parameters of the physical system may vary without appreciably affecting the model results. By means of a first-order sensitivity formalism it is shown how to evaluate the perturbed hydraulic head for a small change in aquifer parameter. An expression for the sensitivity coefficient is obtained in this study by taking the partial derivative of the flow equation with respect to a particular parameter. The sensitivity coefficient is evaluated either analytically or by numerical techniques for some common models. The sensitivity formalism is applied to the Theis equation to study the general behavior of sensitivity coefficients and to determine the range of validity of the first-order sensitivity formalism. The formalism is also applied to one- and two-dimensional numerical models to see the effect of barrier and constant head boundaries. The perturbed hydraulic head is obtained for a change of transmissivity (T) and storage coefficient (S) by applying the first-order sensitivity formalism. This procedure should be a valuable tool in calibrating models or establishing tolerances on T and S for a given acceptable error in hydraulic head. In general, a ±20% deviation in T or S may be handled adequately by the first-order formalism discussed in this work.

End_Page 1006------------------------------Increasing demand and decreasing supply of hydrocarbon products require increased activities in petroleum exploration and production and especially improvement in exploration success. Improvement in exploration success both in previously explored and unexplored areas can only be possible with the integration of all the information and data obtained from geologic, geophysical, geochemical, hydrodynamic, and thermodynamic studies. A three-dimensional deterministic, dynamic model is constructed to calculate all the above measurable values with the help of mass and energy transport equations, and by equations describing the physical and/or physico-chemical changes in organic matter as a function of temperature in sedimentary sequences. Input data consist of heat flux, initial physical and thermal properties of sediments, paleobathymetric estimates, sedimentation rate and amount, and type of organic matter. Then, the model computes pressure, temperature, physical and thermal properties of sediments, maturity of organic matter, and generation and accumulation potential of hydrocarbons as a function of space and time. This model has been successfully applied to four basins with different lithologies (clastics, carbonates, and cyclic sediments) and various structural patterns (halokinesis, faulting, and folding). The allowable error limits are ±3°C for temperature, and ±10% for maturity of organic matter. End_of_Article - Last_Page 1007

Sensitivity analysis is the study of a system's response to various disturbances. In this study disturbances of aquifer parameters, transmissivity (T) and storage coefficient (S) or hydraulic conductivity (K) and specific yield (Sy), are considered. This is termed parametric senstivity which is a measure of the change in output resulting from a disturbance in an aquifer parameter. In the simulation of an aquifer the investigator must establish tolerances within which the parameters of the physical system may change without appreciably affecting the model results. An expression for the sensitivity coefficient is obtained by taking the partial derivative of the flow equation with respect to a particular parameter. The hydraulic head is obtained for a range of aquifer parameter values by applying a first-order sensitivity formalism. This procedure proved to be a valuable tool in calibrating models and establishing tolerances on T and S for a given acceptable error in hydraulic head. In general a ± 20 percent deviation in aquifer parameters can be handled adequately by the first-order formalism in this work. The sensitivity equations and the first-order sensitivity formalism developed in this study are applied to west-central Kansas aquifer. This is an unconfined aquifer which is pumped heavily for irrigation purposes. It is shown that the sensitivity analysis is of great value in the modeling of large systems with arbitrary boundaries and several wells. Thus, it should be an integral part of all computer models.

The following effective diffusion coefficients D(cm2/sec) were determined for the diffusion of light hydrocarbons through the water-saturated pore space of shales: methane (2.12 × 10-6), ethane (1.11 × 10-6), propane (5.55 × 10-7), iso-butane (3.75 × 10-7), n-butane (3.01 × 10-7), n-pentane (1.57 × 10-7), n-hexane (8.20 × 10-8), n-heptane (4.31 × 10-8), and n-decane (6.08 × 10-9). On the basis of these new data, a deterministic, dynamic model was set up to simulate the diffusive transport of light hydrocarbons (C1 to C10) from source rocks. For eight documented source-rock units, representing a wid range of geologic conditions (maturities of 0.40 to 1.35% mean vitrinite reflectance; oil- to gas-prone kerogens), the cumulative amounts of hydrocarbons escaping with time were calculated. Thus, it was shown that diffusion represents an effective process for primary migration of gas but not for oil. The rate of mass transport for gas from source rocks with geologic time can be sufficiently high to account for the origin of commercial-size gas fields. For example, a cumulative amount of 109 kg of methane (1.5 × 109 std m3 or 5.3 × 1010 scf) has escaped by diffusion in 540,000 years from a certain volume (1,000 km2 by 200 m thick) of a high-mature gas-prone Mesozoic source rock in western Canada. The origin of hydrocarbon accumulations with high gas-to-oil ratios in low-mature sediments in geologically young basins ("early gases and condensates") can be explained by an early phase of primary migration predominantly based on diffusion. During the initial stages of the accumulation history of those fields (extending up to millions of years under certain conditions), the reservoir gas changes with geologic time from a methane-rich to a wet-gas composition. At low-maturity levels (below about 0.6% Rm), even oil-prone source rocks yield methane-rich light-hydrocarbon mixtures by migration through diffusion. Compositional trends among reservoir gases of several multiple-pay gas fields in Louisiana represent evidence for diffusive transport of hydrocarbons. The variation in gas composition between the individual pay zones is controlled by increasing distances of diffusive transport of the hydrocarbons from a uniform source rock at depth to their present accumulation sites. In the shallow pay zones, compounds of high diffusivity are enriched. For example, in the Sligo gas field of Louisiana, the methane/ethane and the iso-butane/n-butane ratios increase from 10.2 to 36.0 and from 0.86 to 1.13, respectively, from the deepest to the shallowest of the five productive reservoir sands, which are spread over a a depth interval of 5,500 ft (1,676 m). Diffusion of light hydrocarbons in the subsurface can also have economically adverse effects. For example, existing gas accumulations can be destroyed by dissipation. The rate of this destruction was calculated for the Harlingen gas field, Holland. By diffusive loss through 400 m of shale cap rock, the initial amount of methane in place of 1.93 × 109 std m3 (6.8 × 1010 scf) is reduced by one half over a period of 4.5 million years. This leads us to propose the concept that large gas accumulations can persist through extended periods of geologic time only as dynamic systems reaching some kind of steady-state equilibrium between diffusive loss through the cap rock and continuous replenishment from the source rock.

Basin data--geologic, geophysical, geochemical, hydrodynamic, and thermodynamic--can be combined for quantified hydrocarbon prediction. A three-dimensional, deterministic dynamic basin model can be constructed to calculate all the measurable values with the help of mass- and energy-transport equations and equations describing the physical and/or physicochemical changes in organic matter as a function of temperature. Input data consist of heat flux, initial physical and thermal properties of sediments, paleobathymetric estimates, sedimentation rate, and amount and type of organic matter. Subsequently, the model computes pressure, temperature, physical and thermal properties of sediments, maturity of organic matter, and the hydrocarbon potential of any source rock as a func ion of space and time. Thus the complex dynamic processes of petroleum formation and occurrence in a given sedimentary basin can be quantified. For example, hydrocarbon potential maps for any given source rock and any geologic time slice of the basin evolution can be provided as computer printouts. The computer model can be applied to any stage of an exploration campaign and updated as more information becomes available.