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Recently, rotary ultrasonic-assisted end grinding (RUAEG) has been utilised since it can increment the pace of material elimination and reduce the thrust force. Assigning ultrasonic vibration to the tools was more significant than the other grinding parameters. However, there is no systematic way to choose the cutting parameters to reach efficient outcomes (lower surface roughness and thrust force). The present research employs an adaptive network-based fuzzy inference method to model the RUAEG outcomes, including surface roughness and thrust force, based on the cutting parameters. Moreover, a single objective genetic algorithm is employed to calculate the optimum hyperparameters of the developed adaptive network-based fuzzy inference to reach the highest efficiency. At the end of the process, the multi-objective genetic algorithm is applied to find the optimal machining parameters of RUAEG to achieve the lowest surface roughness and thrust force. The approach is developed using MATLAB with the practically extracted dataset by RUAEG and conventional end-grinding processes of silicon nitride. The optimal cutting parameters are recommended to reach the lowest surface roughness and thrust force. The recommended optimal cutting parameters were able to reach 0.5177 (μm) and 11.8103 (N) for surface roughness and thrust force using the RUAEG method. [ABSTRACT FROM AUTHOR]

Efficient implementation of remote sensing image classification can facilitate the extraction of spatiotemporal information for land use and land cover (LULC) classification. Mapping LULC change can pave the way to investigate the impacts of different socioeconomic and environmental factors on the Earth's surface. This study presents an algorithm that uses Landsat time-series data to analyze LULC change. We applied the Random Forest (RF) classifier, a robust classification method, in the Google Earth Engine (GEE) using imagery from Landsat 5, 7, and 8 as inputs for the 1985 to 2019 period. We also explored the performance of the pan-sharpening algorithm on Landsat bands besides the impact of different image compositions to produce a high-quality LULC map. We used a statistical pan-sharpening algorithm to increase multispectral Landsat bands' (Landsat 7–9) spatial resolution from 30 m to 15 m. In addition, we checked the impact of different image compositions based on several spectral indices and other auxiliary data such as digital elevation model (DEM) and land surface temperature (LST) on final classification accuracy based on several spectral indices and other auxiliary data on final classification accuracy. We compared the classification result of our proposed method and the Copernicus Global Land Cover Layers (CGLCL) map to verify the algorithm. The results show that: (1) Using pan-sharpened top-of-atmosphere (TOA) Landsat products can produce more accurate results for classification instead of using surface reflectance (SR) alone; (2) LST and DEM are essential features in classification, and using them can increase final accuracy; (3) the proposed algorithm produced higher accuracy (94.438% overall accuracy (OA), 0.93 for Kappa, and 0.93 for F1-score) than CGLCL map (84.4% OA, 0.79 for Kappa, and 0.50 for F1-score) in 2019; (4) the total agreement between the classification results and the test data exceeds 90% (93.37–97.6%), 0.9 (0.91–0.96), and 0.85 (0.86–0.95) for OA, Kappa values, and F1-score, respectively, which is acceptable in both overall and Kappa accuracy. Moreover, we provide a code repository that allows classifying Landsat 4, 5, 7, and 8 within GEE. This method can be quickly and easily applied to other regions of interest for LULC mapping. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymers (CFRPs) are widely used in biomedical, optical and tissue engineering applications. Nevertheless, machining these materials significantly differs from other materials and faces special challenges. In recent years, ultrasonic drilling as a new technique was introduced in the field of composites’ machining. This study evaluates the effects of nano-graphene incorporation and machining parameters including feed rate, tool type in both conventional and ultrasonic vibration assisted drilling. Besides, statistical analysis is conducted in order to identify contribution of the parameters. The results suggest that feed rate is the most influential factor on cutting force and hole quality including delamination and hole roundness. In addition, in order to acquire the best optimal process parameters, desirability method was established. That was indicated the best hole quality is achieved in CFRP samples at the least feed rate by the HSS-8% cobalt tool (M42 tool) and in presence of the ultrasonic vibration. [ABSTRACT FROM AUTHOR]

In the present work, optimization attempt based on artificial intelligence has been carried out to minimize the energy consumption of ultrasonic burnishing process subjected to specified range of surface roughness, arc height and hardness. Optimization has been carried out by association of adaptive network based fuzzy inference system (ANFIS) and particle swarm optimization (PSO). It is found from the optimization results that obtaining minimum energy as well as desired quality characteristic is not possible at same time. There is a threshold weight ratio where the energy consumption and workpiece quality are seriously undermined after and before this point, respectively. Hence, this threshold corresponds to the optimum solution of the process. The optimum results have been further verified through confirmatory experiments and there is good correlation between both approaches. • Ultrasonic assisted surface burnishing has been carried out on AA6061-T6 alloy. • The energy consumption, surface roughness, arc height and hardness have been modeled by adaptive network based fuzzy inference system • Multi-objective optimization has been carried out by particle swarm optimization algorithm [ABSTRACT FROM AUTHOR]

• A 3D friction model is developed based on oblique cutting theory. • Conventional and ultrasonic assisted turning and face turning are simulated. • Cutting forces and cutting angles determine the friction value. • The differences of forces plus inclination and rake angles are very effective on friction value. As turning is a 3D operation, development of a friction model considering all cutting forces and angles, is essential. In this study, shear friction model is extended based on oblique cutting theory. The developed model calculates friction value using measured cutting forces coupled with their related angles. To use the model, the operation is carried out in two methods of turning and face turning (with and without ultrasonic vibrations). Then the friction values based on experimental results are calculated. A finite element method is developed to evaluate the accuracy of the values. The results show that the values of simulated tool temperatures are in good agreement with the experiments. Furthermore, the effect of cutting forces on friction values are discussed. [ABSTRACT FROM AUTHOR]

Abstract Silicon nitride is an advanced ceramic used in high performance applications. One of the main problems in machining of brittle materials such as silicon nitride is subsurface damage (SSD). On the other hand, rotary ultrasonic assisted face grinding (RUAFG) is considered as state of the art machining process for brittle and hard to machining materials such as ceramics and optical glasses. In this research, a new study on SSD generation in RUAFG by establishing both ductile deformation and brittle fracture conducted. To achieve this goal, initially single diamond grit cutting force based on Vickers hardness correlation and indentation fracture mechanics established and placed in crack propagation formulas to anticipate SSD. Verification tests performed and average 8% error detected. Moreover, RUAFG depicted up to 30% SSD reduction in comparing to conventional face grinding (CFG). Besides, scanning electron microscope utilized to investigate cracks morphology. [ABSTRACT FROM AUTHOR]

Abstract Ultrasonic surface burnishing (USB) process is a promising surface enhancement technique that improves fatigue life of components by exerting work hardening and compressive residual stress of the surface layers. However, USB is a complex process in practice, and there is not an analytical model published to facilitate the design and comprehension of the process. In the present paper an analytical elastic-plastic model was developed to correlate USB process factors to residual stress field (RSF). Also, deformation of strip samples was determined in the analytical approach. Parameters such static force, ultrasonic vibration amplitude, ball material and its diameter as well as ultrasonic vibration frequency were included in the model to find how they influence the residual stress variation and strip deflection. Two types of material constitutive equation i.e. Johnson-Cook (JC) that is sensitive to strain rate as well as Chaboche hardening that is influenced by cyclic loading were considered to find which material behavior is more consistent with experimental results. The experiments have been carried out on two different materials with various initial state of residual stress field (IRSF). It was obtained from the results that residual stress field variation and strip deflection obtained by experiments are consistent well with the values derived from analytical model. Therefore, the model was comprehensively used to find how the USB process factors influence the RSF and strip deflection. [ABSTRACT FROM AUTHOR]

Highlights • Analytical model of plastic strain based on contact mechanic theorem in ultrasonic burnishing process has been proposed. • Values of plastic strain and relevant distribution have been verified by numerical simulation. • The obtained results of through depth applied strain were completely in line with variation of through depth hardens. Abstract During surface treatment process, microstructure change beneath the surface layers and relevant mechanical properties depend to amount of work hardening occurs through depth of the treated samples. In the present work, an analytical model of surface plastic strain based on contact mechanic theorem is proposed to analyze the ultrasonic burnishing parameters. The model comprises effect of factors such static force, feed rate, ball diameter and ball material as well as ultrasonic vibration parameters such as amplitude and frequency. To incorporate effect of feed rate, two important parameters such as linear coverage coefficient and overlapping ratio have been defined and contributed in the model. The through depth localized plastic strain has been verified by 3D finite element simulation model for different parameter combination. Since, in surface treatment process such as ultrasonic burnishing the surface hardness and microstructure is directly influenced by the plastic strain, a series of experiments have been carried out and through depth hardness profiles has been obtained. It was found from the results that the through depth plastic strain distribution is consistent well with that derived from FE simulation. According to the analytical model, surface plastic strain and relevant affected depth increases by increase of static force and vibration amplitude. Also, it decreases by increase of ball radius and feed rate. On the other hand, it was found that using tungsten carbide ball significantly enhances the surface plastic strain compared to the ball made of steel and silicon nitride. The analytical model of strain and relevant affected depth was completely in line with the variation of through depth hardness and relevant hardened depth. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Highlights • Analytical model of ultrasonic burnishing force has been developed. • Effect of ultrasonic vibration has been included. • Effect of surface elastic recovery has been included. • The results of analytical model were in line with experimental measurements. Abstract In our recently published work i.e. Teimouri et al. [25], mechanic of forces acting during burnishing process has been identified and fully discussed. The process was modeled based on slab method theorem and effect of burnishing parameters on horizontal and vertical forces were identified. However, the present work is an analytical approach to find effect of ultrasonic vibration parameters and pass number considering elastic rebound of work surface. In the proposed methodology effect of different parameters such as feed rate, ball diameter, depth of burnishing, vibration amplitude and pass number on the burnishing force. The comparison with experimental results allows to affirm that the model is a useful tool to predict the value of resultant burnishing force. [ABSTRACT FROM AUTHOR]

In this study, ultrasonic assisted drilling (UAD) is performed to investigate the effect of ultrasonic vibrations on common difficulties existed in conventional drilling (CD). UAD is a promising and advanced technique by which a harmonic movement with high frequency and low amplitude is superimposed on the movement of work material or cutting tool. The study is conducted both experimentally and numerically; at first, a UAD system is designed, manufactured, and carried out on a milling machine and then experimental tests are accomplished. In the following, experimental results are supported by the help of three-dimensional (3D) finite element simulation. Finally, the dependent parameters such as the burr height and cylindricity of the ultrasonically and conventionally drilled workpiece are measured and compared. Briefly, it was proved that the intermittent movement of drill bit in the direction of feed rate results in broken and discontinuous chips by which built-up-edge (BUE) is reduced and hole quality is improved. In addition, the burr height, which is known as unwanted projection of material at the exit surface of pieces, can notably decrease, if UAD is considered. [ABSTRACT FROM AUTHOR]

Modification of conventional turning operation is carried out by using different methods to improve machinability conditions. In this study, rotary turning is modified by adding ultrasonic vibrations to cutting tool. Accordingly, the effect of this method on output parameters namely, tool wear and temperature, cutting force, and surface roughness, is investigated. Having detailed analysis, finite element method is used beside the experiments. As a result, it was revealed that tool-chip engagement time during rotary motion of cutting tool significantly reduced wear propagation on tool faces. This was explained by heat analysis in which disengagement time resulted in lower heat transfer from chip to tool. Moreover, the result of surface roughness produced in vibratory-rotary turning was compared by rotary one. [ABSTRACT FROM AUTHOR]

High quality of machined surfaces is an important requirement in production industries. Therefore, different methods such as ultrasonic vibrations are implemented to improve this parameter. In this study, it is tried to specify some of effective parameters on surface improvement in ultrasonicassisted turning. Accordingly, a series of experiments in the way of conventional and vibratory turning are conducted where surface roughness and surface topography are evaluated as main objectives of this work. Furthermore, analysis of tool wear and radial displacement of tool and workpiece are carried out for explanation of surface enhancement in vibratory turning. As a result, it is shown that generated typical peaks and valleys in conventional turning are flattened and reduced in vibratory turning which is explained by existence of lower radial force. [ABSTRACT FROM AUTHOR]

Ultrasonic assisted ball burnishing process is a newly developed alternative of conventional ball burnishing process that enhances the surface properties of engineering materials through imposing both the static and dynamic loadings. The process needs careful selection of design parameters to improve the performance measures such as surface roughness and hardness. In the present study an experimental investigation was carried out to analyze effect of ultrasonic vibration amplitude, feed rate and static force on surface roughness and hardness of aluminum 6061-T6 alloy. Here, number of 20 experiments was carried out through face centered central composite design and values of surface roughness and hardness after each experiment were measured. Hereafter, response surface methodology (RSM) was utilized to correlate empirical relationship between process parameters and responses. Further, numerical simulation of process using ABAQUS software has been carried out to study states of residual stress and plastic equivalent strain under different processing condition. Results indicated that in order to achieve maximum hardness and minimum surface roughness simultaneously, ultrasonic vibration amplitude of 8 µm, feed rate of 1000 mm/min and static force of 38 N, should be selected. The obtained optimal results were then experimentally verified and the prediction errors for both the responses were lower than 10%, implying rigidity of proposed methodology in finding the optimum results. The results obtained by FE simulation showed that the maximum value and effective depth of compressive residual stress in ultrasonic assisted process is significantly higher than that of conventional burnishing. [ABSTRACT FROM AUTHOR]

In this study, the use of ultrasonic peening technology (UPT) on the rolling mill roll graphite steel GSH48 was surveyed in order to improve some surface mechanical and thermal properties. UPT is one of the newest technologies of severe plastic deformation in which vibratory tool strikes the workpiece surface with continual reciprocating motions, resulting in severe plastic deformation on the surface. This method enhances mechanical and thermal properties like fatigue life and thermal fatigue. Thermal fatigue in the rolling mill rolls causes the growth of crack on the surface and growing that in depth leads to the break of the roll. The influence of the UPT on the improvement of thermal fatigue life of the hot-rolling rolls was investigated by conducting thermal fatigue test in which parameters were adjusted in accordance with the process of hot-rolling. By the simulation and manufacturing of peening vibratory tool, preparation of the process was accomplished including setting up the ultrasonic vibratory tool on lathe machine. According to the standard of related devices, samples were prepared form the surface of roll and the examinations of fatigue, thermal fatigue, and surface topology by atomic force microscopy (AFM) were performed on workpieces in different states before and after the UPT process with one, two, and three passes. The process of ultrasonic peening caused severe plastic deformation on surface layers and prevented from crack growth. The results of this research indicated the rise of the fatigue and thermal fatigue life of the pieces after UPT process. [ABSTRACT FROM AUTHOR]

Conventional drilling (CD) which is known by two rotary and linear motions is considerably used in material removal processes; however, this method cannot satisfy the new demands of modern industry anymore, encountering with some serious technological constraints such as fast tool wear, high thrust force, and so on. A new and promising method which has been used recently as an alternative technique to cope or at least diminish common difficulties in CD is imposing ultrasonic vibrations to the cutting process, where vibrations usually with high frequency and low amplitude are superimposed in the movements of cutting tool. This study is a new exercise which considers the effects of one and two directional ultrasonic vibrations in drilling of AISI 1045 compared to CD. In one directional technique known as longitudinal ultrasonic assisted drilling (L UAD), ultrasonic vibrations are added to the feed motion and in two directional vibrations; ultrasonic vibrations are simultaneously applied to both feed and rotary motions known as longitudinal-torsional ultrasonic assisted drilling (L-T UAD). The study which is performed both experimentally and numerically does its best to evaluate and compare the obtained results in CD, L UAD, and L-T UAD. In experimental part, a system including two vibratory tools and a rotary mechanism is designed, fabricated, and then assembled with other equipment on a milling machine to accomplish drilling tests. In numerical part, a FE model is also developed with the aim of further understanding of experimental results, by which drilling operations either conventional or vibratory in different forms can be conducted and studied. As a brief conclusion, it was found that ultrasonic vibrations can be used as an effective tool for enhancement of drilling process and longitudinal-torsional vibrations reveal better results than longitudinal vibrations. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced plastics are used in variety of industrial and constructional applications for their superb mechanical and physical properties. Delamination is one of the most important and prevalent damages in machining of glass fiber reinforced plastics. Diamond core drills have the capability of simultaneously drilling and grinding of fiber reinforced plastics, which results in hole quality improvement. Rotary ultrasonic-assisted drilling is the new machining process to drill holes on fiber reinforced plastics and has attracted increasing attention in recent years. In this paper, thrust force and delamination in rotary ultrasonic-assisted drilling of glass fiber reinforced plastics using diamond core drill have been investigated. A proper ultrasonic system for a core drill in ABAQUS was designed and fabricated. Influence of ultrasonic vibration and then tool grain size, fiber-volume fraction and machining parameters including spindle speed and feed rate on thrust force and delamination was investigated. Higher thrust force induces more delamination. As a result of the study, less delamination was achieved in ultrasonic-assisted mode by using a tool with larger grain size onto lower fiber-volume fraction composites. Additionally, experiments showed that lower spindle speed and higher feed rate induce more delamination. [ABSTRACT FROM AUTHOR]

Conventional drilling (CD) which is known by two constant rotary and linear motions causes some problems in drilling of materials such as high thrust force, poor surface quality, and rapid tool wear. To get rid of these problems or at least minimize them, a promising technology has been employed in the recent years, where vibrations usually with low amplitude and high frequency are applied to the direction of feed motion results in a time-dependent velocity between drill tip and workpiece. This paper focuses on the design of a vibratory tool following by experimental and numerical approaches to study the influence of longitudinal ultrasonic vibrations on drilling of aluminum alloy 7075. Experimental part is a comprehensive exercise to design, fabricate, and test a system equipped with different instruments to work in desired conditions. Experimental results are supported by a finite element method to better comprehend what is happening in cutting process when ultrasonic vibrations are added. The achieved results prove that using ultrasonic-assisted drilling (UAD), the machining ability of drilled aluminum workpiece can enhance significantly. Improvement of up to 40% for drill circularity and a reduction of up to 37% in thrust force were achieved. [ABSTRACT FROM AUTHOR]

In this study, influence of added linear vibration of cutting tool on the performance of rotary turning of AISI 4140 steel is investigated. Experimental tests are carried out at different cutting and tool rotary speeds by using special equipment for ultrasonic assisted rotary turning. The results of surface roughness, cutting force, and tool wear obtained during vibratory-rotary cutting are compared by the values of conventional and rotary turning. At the end, it is shown that lower displacement of workpiece in the radial direction, decrease of tool rake angle, and producing cooling cycle during disengagement time in vibration cutting cause lower wear distribution along the circumference of cutting tool. As a consequence to that, a significant reduction in surface roughness and cutting force is observed compared to the conventional and rotary turning. Besides, effect of variations in tool rotary and cutting speeds on output parameters are evaluated. [ABSTRACT FROM AUTHOR]

Enhancing the surface properties of engineering elements significantly influence the structure life and increases the functionality. The surface treatment process has great impact on improving the surface properties such as, fatigue life and hardness. In the present study an innovative surface treatment technique namely laser shock peening (LSP) was utilized to enhance the fatigue life, residual stress and surface hardness of nickel-based super alloy Incoloy 800. Here, effect of parameters such as spot diameter, pass number and laser power on aforementioned responses has been experimentally investigated. It is found from the results that increase in spot diameter, number of shocks and laser power results to impressive enhancement of fatigue life and surface hardness about 150% and 25%, respectively. It is also found that the surface protection and absorbent layer has great impact on effectiveness of LSP, where, in high laser power the absorbent layer is deteriorated due to high thermal energy that has negative influence on fatigue life and changes the type of residual stress from compressive to tension. [ABSTRACT FROM AUTHOR]

Studying the effect of longitudinal ultrasonic vibrations on the performance of incremental forming process of aluminum-1050 sheet is the main purpose of this paper. In this new technique, ultrasonic vibrations with high frequency and low amplitude are axially added to the movement of forming tool. To fulfill this purpose, a system was carefully devised. This system consists of different parts including a mechanism attached into the chuck of CNC machine to give rotary motion and also sent ultrasonic power to the vibratory tool. Straight groove test was performed, and various parameters including forming force and sheet formability were investigated in both conventional and ultrasonic-assisted incremental forming process. The achieved results show that ultrasonic assistance can increase formability and decrease forming force significantly. [ABSTRACT FROM AUTHOR]

In this study, 3D finite element simulation of ultrasonically-assisted drilling is carried out to analyze the effect of ultrasonic vibrations on common difficulties existed in conventional drilling. Influence of harmonic movement of drill bit on the formation of built-up edge is experimentally evaluated and also discussed by investigation of heat generation on the tool faces in simulation. At the end, it was revealed that intermittent movement of drill bit in vibration method causes the total time of heat transfer between workpiece and drill bit to be reduced resulting lower built-up edge formation compared to conventional drilling. Moreover, linear motion of cutting tool in the feed direction results in the increase of chip strain and consequently damage value which causes to generation of broken chips. [ABSTRACT FROM AUTHOR]

Producing mechanical components with long time functioning is a vital issue in the advanced industries. Wear is one of serious difficulties which prevents from achieving desires. The objective of present study is how wear-resistance of a spool valve, which is an important part of hydraulic valves, can be improved. Hence, different heat treatment methods were implemented to harden the surface layer of this component which is an AISI 1.7225 steel. Wear-resistance measurement test coupled with roughness and distortion tests have been performed to run this analysis. Furthermore, a vision measuring microscope was used to investigate the quality of surfaces that impaired by the wear test. As a result of this work, it was revealed that surface hardening methods generally outperformed the bulk hardening process. In particular, carburizing surface hardening method generates the surfaces with ability of high wear-resistance and better surface quality compared to the other heat treatment processes used in this study. Moreover, highest distortion occurred in the spool valve when gas carburizing heat treatment method has been carried out. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is known as a post processing surface treatment which can improve the mechanical properties of some materials. Shock waves are generated by confining the laser-induced plasma to cause a large pressure shock wave over a significant surface area. In the present study, effects of LSP on the electrochemical corrosion and micro hardness properties of 316L stainless steel alloy were investigated by changing the laser parameters such as the laser spot size, the average number of impacts, and the laser intensity. Since laser parameters do not cover the desired region of LSP, we have to use the proper design of experiment method, in which the D-optimal design of MATLAB was selected. Results revealed that by increase in irradiance, number of impacts and spot size of laser beam, improvement in the surface micro hardness, and corrosion resistance is achieved. Also, due to unexpected drop into the outcome of our experiments, it was found that the contamination of the transparent overlay and reduction of the absorption coefficient of the absorbent layer play a key role to reduce the efficiency of the mechanical impacts. So, by changing the experimental conditions, even better results are expected. [ABSTRACT FROM AUTHOR]

Beside beneficial aspects of friction stir welding such as solid-state joining process, no melting, no recasting, etc., there are some disadvantages like considerable axial forging force especially for high-strength materials. Researchers have developed several innovative ideas to diminish the process problems. In the present study, to investigate the effect of bending vibrations, an ultrasonic vibratory tool of friction stir welding, in bending mode, has been designed and manufactured. Firstly, the vibratory tool was designed for the operating resonance frequency of 20 KHz in ABAQUS software. This tool consists of transducer, horn, and welding tool. Using the optimal dimensions achieved from the modal analysis, the FSW tool has been manufactured. Then, experimental investigations verify the validity of the tool design process, such as clamping flange position, resonance frequency, and so on. The friction stir welding of aluminum Al6061 and Teflon plates has been done with lathe machine. FSW-assisted ultrasonic vibrations in bending mode show some advantages in comparing with linear mode, such as decreased tool length and increased efficiency of vibrational energy transferring to the tool tip. Finally, with respect to the indicated improvements, reduction and rise of welding forces and temperature have been observed, respectively. [ABSTRACT FROM AUTHOR]

One of the main problems in the machining of thin-walled parts made of high-strength aluminum alloys is distortion and dimensional instability after machining, which leads to an increase in scraped parts and the cost of production. In general, distortion and dimensional instability in machined parts made of aluminum alloy is a function of the residual stresses. In this article, the correlation between machining-induced residual stresses and distortion in a thin-walled work pieces is investigated. Several experiments are carried out under different machining conditions using two carbide and polycrystalline diamond (PCD) tools on a thin-walled cylinder made of AL7075-T6 alloy. Rates of variations in geometrical tolerances and distortion for all work pieces are measured. To study the effect of mechanical and thermal loads on the residual stresses and distortion, the machining force and temperature of cutting area are measured. Finally, the correlation between the residual stress and distortion is studied by measurement of residual stress on some work pieces. Similarly, in order to investigate the effect of work pieces thickness on distortion, several tests are carried out on three work pieces with different thicknesses. The results indicate that the force and temperature have direct effect on the residual stresses and distortion in the thin-walled parts. [ABSTRACT FROM AUTHOR]

Due to the high variation of aerosol in space and time, remote sensing has become an effective tool in aerosol optical depth (AOD) retrieval. Most of the satellite-based AOD retrieval methods using the radiative transfer model (RTM). RTMs help to establish a relation between AOD and the observed top-of-atmosphere (TOA) reflectance. Using look-up table-based approaches is among the commonly used methods for reducing the computational complexity in RTMs. Tuning steps for parameters in the LUTs influences computational cost and accuracy of retrieved satellite-based AOD. However, a comprehensive and quantitative assessment for the construction of LUT based on sensitivity analysis does not exist. In this paper, we present a sensitivity analysis approach called Morris one-at-a-time (MOAT) for identifying parameters that dominate model behaviour in the AOD retrieval process. We also use 8 cases to tune steps for each parameter in the look-up table. We investigate the influence of geometrical and physical parameters in the 6S RT code on radiance and reflectance. The result indicated that ground reflectance, aerosol model, and single scattering albedo are dominant parameters in LUT construction. Other geometrical and physical parameters have less impact on the simulated radiance and reflectance. Finally, we tuned proper steps for LUT construction based on the trend and behaviour of each parameter. The proposed method in this study can improve the accuracy of satellite-based AOD by constructing a LUT with a short processing time. • Tuning proper step for parameters in LUT construction. • Different behavior of simulated radiance and reflectance for some parameters. • More discrepancy in the behavior of parameters for radiance/reflectance in green wavebands. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to assess the benefits and possible risks of aerobic exercise during pregnancy using a fitness regimen based on the 2002 American College of Obstetricians and Gynecologists guidelines for exercise during pregnancy. Researchers evaluated 62 pregnant women who either remained sedentary or performed moderate aerobic exercise for 45-60 minutes four days per-week through 36 weeks of gestation. They found that previously sedentary women who began exercising at 12-14 weeks of pregnancy had improved fitness and delivery outcomes.

Rapid and timely evaluation and monitoring of the urban environment has gained significant importance in understanding the state of urban sustainability in metropolises. Multi-source remote sensing (RS) data are a valuable source for a comprehensive understanding of urban environmental changes in developing countries. However, in the Middle East, a region with several developing countries, limited study has been conducted to understand urban environmental changes. In this study, to evaluate the changes in the urban environment, 32 metropolises in the Middle East were studied between 2000 and 2019. For this purpose, a comprehensive environmental index (CEI) integrated with Google Earth Engine (GEE) platform for processing and analysis is introduced. The results show degraded environmental conditions in 19 metropolises based on a significant increasing trend in the time series of the CEI index. The highest increasing trend in the value of the CEI was observed in the cities of Makkah, Jeddah, Basra, Riyadh, and Sana'a. The results also show that the percentage of urban areas in all 32 cities that falls into the degraded class varies from 5% to 75% between 2005 and 2018. The results of CEI changes in megacities, such as Ajman, Tehran, Jeddah, Makkah, Riyadh, Karaj, and Sana'a show that these cities have increasingly suffered from the degradation of environmental conditions since 2001. According to the results, it is recommended to pay more attention to environmental issues regarding the future of urban development in these cities. The proposed approach in this study can be implemented for environmental assessment in other regions. [ABSTRACT FROM AUTHOR]

Purpose: This cross-sectional study aimed to investigate the potential of voice analysis as a prescreening tool for type II diabetes mellitus (T2DM) by examining the differences in voice recordings between non-diabetic and T2DM participants. Methods: 60 participants diagnosed as non-diabetic (n = 30) or T2DM (n = 30) were recruited on the basis of specific inclusion and exclusion criteria in Iran between February 2020 and September 2023. Participants were matched according to their year of birth and then placed into six age categories. Using the WhatsApp application, participants recorded the translated versions of speech elicitation tasks. Seven acoustic features [fundamental frequency, jitter, shimmer, harmonic-to-noise ratio (HNR), cepstral peak prominence (CPP), voice onset time (VOT), and formant (F1–F2)] were extracted from each recording and analyzed using Praat software. Data was analyzed with Kolmogorov–Smirnov, two-way ANOVA, post hoc Tukey, binary logistic regression, and student t tests. Results: The comparison between groups showed significant differences in fundamental frequency, jitter, shimmer, CPP, and HNR (p < 0.05), while there were no significant differences in formant and VOT (p > 0.05). Binary logistic regression showed that shimmer was the most significant predictor of the disease group. There was also a significant difference between diabetes status and age, in the case of CPP. Conclusions: Participants with type II diabetes exhibited significant vocal variations compared to non-diabetic controls. [ABSTRACT FROM AUTHOR]

Provides estimates of race- and sex-specific survival rates of Medicare patients admitted to a hospital in 1984 with a diagnosis of pulmonary embolism. Decline of survival rates with advancing age; Use of Kaplan-Meier estimates of survival functions for diagnosis of pulmonary embolism; Determination of death rate.

Improvement of surface integrity is one of the machining desires where different parameters are related to this phenomenon. Therefore, the effect of 3D elliptical vibration on different aspects of surface integrity is investigated, in this study. Surface roughness, microstructure changes (grain size), and microhardness plus cutting forces and tool-chip friction are experimentally investigated. Moreover, to clarify more details, finite element simulation of microstructure changes is carried out when conventional and 3D elliptical ultrasonic assisted turning of Ti–6Al–4V alloy are implemented. As a result, it was revealed that 3D vibration method causes the smaller grain size to be generated compared to conventional process. In addition, this method could improve the isotropy of the surface by generation of semi-spherical micro-textures. Image 1 • Experimental and 3D finite element simulation of microstructure changes are carried out. • A 3D ultrasonic assisted turning tool is used to evaluate of surface integrity of Ti–6Al–4V. • 3D vibrations could reduce the grain size improving the surface microhardness. • Semi-spherical micro-textures were generated by using 3D vibrations improving surface isotropy. [ABSTRACT FROM AUTHOR]

• 3D elliptical vibration method is represented to evaluate its effect on surface integrity in boring. • 3D vibration reduces the depth of microstructure changes and improves surface microhardness. • The feed-marks in conventional boring of Titanium are changed to micro-textures in vibratory method. • 3D vibration eliminates the adhesion of working material which is happened in conventional one. Improving surface integrity is an important issue to enhance wear resistance and fatigue life of the end product. Thus, a 3D elliptical vibration method is represented to evaluate its effect on the parameters of surface integrity in boring process. The operation is carried out on a titanium cylinder in two methods of conventional and 3D elliptical ultrasonic assisted boring. After the machining, surface roughness, microstructure changes, and microhardness of the cut surfaces are examined. The results show that 3D vibration causes the depth of microstructure changes to be less than conventional boring, while it increases the surface hardness, more. In addition, this method almost eliminates the effect of cutting parameters on surface roughness by producing micro-textures on the surface. [ABSTRACT FROM AUTHOR]

• Cutting force model based on both ductile and brittle deformation in RUAEG of Si3N4. • Ultrasonic applying on the tool reduces cutting force up to 64% • Theoretical model trend is in good accordance with the experimental results. Rotary ultrasonic assisted end grinding (RUAEG) is a new machining process that has attracted numerous researchers. This paper presents a theoretical model to predict cutting force in RUAEG of Si3N4 ceramics. Since cutting process includes both ductile deformation and brittle fracture, combination of ductile deformation and brittle fracture will be considered that was a novelty of this investigation. Analyses were carried out based on indentation fracture theory and Vickers hardness relationships. Afterwards, verification experiments demonstrated mean error value of 17.27% between theoretical model and experimental values. Based on the presented model, input machining variables and tool properties variation influence on cutting force were investigated. The present research outcome can be a reliable model to predict cutting force more precisely and understand the cutting mechanism in RUAEG. In the following, RUAEG process and conventional end grinding results were compared that was observed in RUAEG, cutting force could be reduced up to 64%. [ABSTRACT FROM AUTHOR]

Improving the surface quality of additive manufactured parts like poly lactic acid (+) is an important study that is currently being carried out by researchers. To reach the high-quality, different conventional and nonconventional methods are applied. In this study, the capability of ultrasonic vibration in drilling of an additive manufactured poly lactic acid (+)was examined. The process was implemented in two methods: conventional and vibratory drilling. Then, thrust force and chip type were analyzed, and the effect of them on surface roughness, delamination, circularity, and cylindricality have been investigated. As a result, it was indicated that lower thrust force and broken chips, which were generated in ultrasonic drilling, caused the surface quality parameters to be improved compared to the conventional method. [ABSTRACT FROM AUTHOR]

• The effect of UP was studied on the corrosion behavior of L-PBFed CP-Ti. • UP resulted in a well-refined and dense microstructure comprising fine acicular α'-M. • Applying 3-pass UP significantly improved the corrosion resistance of L-PBFed CP-Ti. Surface modification of metal Additive Manufacturing (AM) components has gathered a lot of interest recently. Ultrasonic Peening (UP) was employed to improve the corrosion properties of Laser Powder Bed Fusion (L-PBF) processed commercially pure titanium (CP-Ti). UP process forged the surface porosities, significantly refined the acicular martensites (α'-M) formed during the L-PBF, and homogenized the microstructure. These significantly enhanced the corrosion behavior of L-PBF processed CP-Ti, by reducing the corrosion current from 4.8 µA/cm2 to 0.72 µA/cm2 after a 3-pass UP. Accordig to the FESEM observations, the corroded surface of the 3-pass UPed sample was covered by a protective oxide film implying its uniform corrosion. [ABSTRACT FROM AUTHOR]

Machining process of glass fiber composites usually induces delamination damage. The presence of delamination may cause changes in the mechanical characteristics of the composite structures. In this research, a comprehensive experimental study is performed to analyze the influence of different parameters such as thermal fatigue, lay-up arrangement, resin type, feed rate and cutting velocity on the delamination of glass fiber composites under different drilling processes. Besides, influence of ultrasonic vibration exerting on the tool as a new and high-tech process is investigated. To follow this aim, different composite specimens with various resin types and lay-up arrangements are fabricated and a thermal fatigue condition is provided. Additionally, the Taguchi method is employed to obtain the optimized damage reduction condition in terms of mentioned parameters. The results indicated that thermal fatigue and unsymmetrical lay-up arrangement result in more delamination damage. It was also established that the influence of mentioned parameters is more considerable in higher cutting velocities. Moreover, ultrasonic vibration application is suggested to have the least delamination damage. [ABSTRACT FROM AUTHOR]

Application of glass fiber reinforced polymers (GFRP) has been appreciably increased in recent decades because of their admirable properties. Thus, various investigations are focused in machinability of GFRPs. Delamination is one of the major damages in drilling of GFRPs. Rotary ultrasonic drilling (RUD) is a state-of-the-art drilling operation that has been noticeably considered in composites machining industry. In this paper, delamination of GFRPs in RUD process is examined. To reach the goal, appropriate ultrasonic system was established and using a HSS tool, the experiments were carried out. Then, the influence of multi-walled carbon nanotube (MWCNT) addition, thermal fatigue and drilling parameters on delamination were investigated. Additionally, statistical analysis was performed. The results showed that the delamination quality can be well optimized by increase of the cutting velocity. It was also established that thermal fatigue condition results in delamination deterioration. In contrary, addition of nanoparticles enhances the delamination state. [ABSTRACT FROM AUTHOR]

Like many developing countries, Iran faces air pollution, especially in its metropolises and industrial cities. Nitrogen dioxide (NO2) is one of the significant air pollutants; therefore, this study aims to investigate the spatiotemporal variability of NO2 using Tropospheric Monitoring Instrument (TROPOMI) sensor mounted on the Sentinel-5P (S5P) satellite and the Google Earth Engine (GEE) platform over Iran. In addition, we used ground truth data to assess the correlation between data acquired by this sensor and ground stations. The results show that there is a strong correlation between products of the TROPOMI sensor and data provided by the Air Quality Monitoring Organization of Iran. The results also display that the correlation coefficient (R) of NO2 between ground truth data and the TROPOMI sensor varies in the range of 0.4 to 0.92, over three years. Over an annual period (2018 to 2021) and wide area, these data can become valuable points of reference for NO2 monitoring. In addition, this study proved that the tropospheric NO2 concentrations are generally located over the northern part of Iran. According to the time and season, the concentration of the tropospheric NO2 column shows higher values during winter than in the summertime. The results show that a higher concentration of the tropospheric NO2 column is in winter while in some southern and central parts of the country more NO2 concentration can be seen in the summertime. This study indicates that these urban areas are highly polluted, which proves the impact of pollutants such as NO2 on the people living there. In other words, small parts of Iran are classified as high and very highly polluted areas, but these areas are the primary location of air pollution in Iran. We provide a code repository that allows spatiotemporal analysis of NO2 estimation using TROPOMI time-series images within GEE. This method can be applied to other regions of interest for NO2 mapping. [ABSTRACT FROM AUTHOR]

Our primary objective was to evaluate changes in energy expenditure and body composition in women with normal glucose tolerance (NGT) and gestational diabetes mellitus (GDM). A secondary objective was to examine the relationship between maternal leptin and nutrient metabolism. Fifteen obese women, eight with NGT and seven with GDM, were evaluated before conception (P), at 12-14 wk (E), and at 34-36 wk (L). Energy expenditure and glucose and fat metabolism were measured using indirect calorimetry. Basal hepatic glucose production was measured using [6,6-²H2]glucose and insulin sensitivity by euglycemic clamp. There was a significant increase (6.6 kg, P = 0.0001) in fat mass from P to L. There was a 30% (P = 0.0001) increase in basal O2 consumption (VO2, ml/min). There were no significant changes in carbohydrate oxidation during fasting or storage from P to L. There was, however, a significant (P = 0.0001) 150% increase in basal fat oxidation (mg/min) from P to L. Under hyperinsulinemic conditions, there were similar 25% increases in VO2 (P = 0.0001) from P to L in both groups. Because of the significant increases in insulin resistance from P to L, there was a significant (P = 0.0001) decrease in carbohydrate oxidation and storage. There was a net change from lipogenesis to lipolysis, i.e., fat oxidation (30-40 mg/min, P = 0.0001) from P to L. Serum leptin concentrations had a significant positive correlation with fat oxidation at E (r = 0.76, P = 0.005) and L (r = 0.72, P = 0.009). Pregnancy in obese women is associated with significant increases in fat mass and basal metabolic rate and an increased reliance on lipids both in the basal state and during the clamp. These modifications are similar in women with NGT and GDM. The increased reliance on fat metabolism is accompanied by a concomitant decrease in carbohydrate metabolism during hyperinsulinemia. The increase in fat oxidation may be related to increased maternal serum leptin. [ABSTRACT FROM AUTHOR]

Background: Evidence concerning the impact of long-term exposure to fine Particulate Matter ≤2.5 μm (PM2.5) on Cardio-Vascular Diseases (CVDs) for those people subject to ambient air pollution in developing countries remains relatively scant. This study assessed the relationship of 15-year PM2.5 exposure with cardiovascular incidence and mortality rate in Isfahan province, Iran.Methods: The cohort comprised 3081 participants over 35 years old who were free of CVDs. They were selected through multi-stage cluster sampling in Isfahan, Iran. PM2.5 exposure was determined separately for each individual via satellite-based spatiotemporal estimates according to their residential addresses. In this context, CVD is defined as either fatal and non-fatal Acute Myocardial Infarctions (AMI) or stroke and sudden cardiac death. The incidence risk for CVD and the ensuing mortality was calculated based on the average PM2.5 exposure within a study period of 15 years using the Cox proportional hazards frailty model upon adjusting individual risk factors. The mean annual rate of PM2.5 and the follow-up data of each residential area were combined.Results: Mean three-year PM2·5 exposure for the cohort was measured at 45.28 μg/m3, ranging from 20.01 to 69.80 μg/m3. The median time period for conducting necessary follow-ups was 12.3 years for the whole population. Notably, 105 cardiovascular and 241 all-cause deaths occurred among 393,786 person-months (27 and 61 per 100,000 person-months, respectively). In well-adjusted models, 10 μg/m3 increase in PM2.5 corresponded to a 3% increase in the incidence rate of CVDs [0.95 CI = 1.016, 1.036] (in case of p = 0.000001 per 10 μg/m3 increase in PM2.5, the Hazard Ratio (HR) for AMI and Ischemic Heart Disease (IHD) was 1.031 [0.95 CI = 1.005, 1.057] and 1.028 [0.95 CI = 1.017, 1.039]), respectively. No consistent association was observed between PM2.5 concentration and fatal CVD (fatal AMI, fatal stroke, SCD (Sudden Cardiac Death)) and all-cause mortality.Conclusions: Results from analyses suggest that the effect of PM2.5 on cardiovascular disease occurrence was stronger in the case of older people, smokers, and those with high blood pressure and diabetes. The final results revealed that long-term exposure to ambient PM2.5 with high concentrations positively correlated with IHD incidence and its major subtypes, except for mortality. The outcome accentuates the need for better air quality in many countries. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To develop a more accurate ultrasound birth weight ( BW ) model using neonatal anthropometric measurements. STUDY DESIGN: Two hundred thirty - one newborns were evaluated. Measurements included weight; head, chest, and abdominal circumferences ( umbilicus and liver ), humerus, and femur lengths. Infants were randomly assigned into two groups (G[SUB1] and G[SUB2]. Anthropometric measurements that are obtainable by ultrasound were generated from G[SUB1]. Stepwise regression and a bootstrap analysis were used to create the prediction models. The models were validated using G[SUB2] RESULTS: The final stepwise regression model included FL and circumferences of the head, chest, and abdomen. The correlations were: G[SUB1] : R[SUP2] = 0.91, p < 0.001; G[SUB2]: R[SUP2] = 0.90 p < 0.001. There was no difference between derived and actual BW in G[SUB1] (p = 0.42 ) or G[SUB2] (p = 0.28 ). The mean absolute percent error between the prediction model and actual BW was 3.8%. CONCLUSION: Neonatal anthropometric models are strongly predictive of actual BW. This model will be tested prospectively using ultrasound to predict fetal weight. [ABSTRACT FROM AUTHOR]

Background: Telemedicine focuses on providing medical care to patients in remote locations using telecommunication technologies. It has been shown to be cost-effective, improve health outcomes, and enhance patient satisfaction. This study examines the extent to which medical students and resident physicians are exposed to telemedicine during training. Materials and Methods: The authors accessed the American College of Graduate Medical Education (ACGME) Residency Milestones from specialties and subspecialties mentioned in the 2018 Milestones National Report and searched for key terms, including "Technology," "Telemedicine," "Telehealth," "EMR," "Electronic Medical Record," "EHR," "Electronic Health Record," "Electronics," and "Social Media." The authors also accessed the 2018 American Association of Medical Colleges (AAMC) "Curriculum Inventory and Reports" to retrieve data from surveys of medical schools that included telemedicine in required courses and electives for medical students from 2013 to 2018. Results: From the 104 ACGME specialty milestones, only one specialty (Child and Adolescent Psychiatry) mentioned telehealth in its ACGME Milestone document. According to the AAMC data the number of medical schools surveyed increased every academic year from 140 in 2013/2014 to 147 in 2017/2018, telemedicine education in medical school increased significantly from 41% in 2013/2014 to 60% in 2017/2018 (p = 0.0006). However, the growth in telemedicine education plateaued from 56% in 2015/2016 to 60% in 2017/2018 (p = 0.47). Conclusion: Familiarizing medical students with telemedicine is essential; the next generation of health care providers should be equipped with knowledge of telemedicine as a valuable skill to serve populations that do not have direct access to quality medical care. Methods of implementing telemedicine education into more medical schools and residency programs merits further study. [ABSTRACT FROM AUTHOR]

This study was performed to evaluate the effect of type 1 diabetes mellitus (T1DM) on the microhardness of tooth enamel and dentine in mice. Seventy male C57BL/6 J mice were used in this study. Thirty-five mice were rendered diabetic by administration of streptozotocin (STZ), and the remaining animals received citrate buffer (normal/non-diabetic). In each group, specimens were divided into 7 subgroups of 5 mice based on the time points 0, 1, 4, 8, 12, 20, and 28 weeks. The microhardness value (MHV) of the second molars' enamel and root dentine were tested with a Vickers microhardness tester. Five specimens from each subgroup were evaluated for dentinal tubular density by scanning electron microscope (SEM) and color dot map analysis to determine the color intensity of strontium (Sr) and magnesium (Mg) by using ImageJ software. The MHV of enamel was significantly reduced in STZ specimens in time points of 12 weeks (STZ: 274.39 ± 15.42, normal: 291.22 ± 15.28), 20 weeks (STZ: 247.28 ± 19.65, normal: 290.68 ± 11.52), and 28 weeks (STZ: 232.87 ± 15.07, normal: 282.76 ± 10.36) (P < 0.05). When comparing the MHV of dentine in subgroups of the normal group, after 20 weeks (169.1 ± 7.5) and 28 weeks (168.6 ± 7.81), the MHV increased significantly (P < 0.05). However, in the STZ group, a significant reduction of MHV was noticed between 28 weeks (131.69 ± 6.2) specimens with other subgroups (P < 0.05). T1DM negatively affected enamel and dentine microhardness, and enamel was influenced much more negatively and rapidly compared with dentine in diabetic groups. • Diabetes decreases Vickers microhardness (MHV) of both enamel and dentine. • MHV decreases in enamel and increases in dentine due to aging in wild type mice. • Diabetic MHV decreased significantly after 12 weeks in enamel and 28 weeks in dentine. • Diabetes affects enamel microhardness more than dentine. • Aging is remarkably correlated with changes in microhardness of enamel and dentine. [ABSTRACT FROM AUTHOR]

The article presents a study that identifies whether neonates of African-American women have lower birth weights due to decreased lean body mass or fat mass than neonates of Caucasian women. The study examined 104 African-American and 274 Caucasian term, singleton and healthy pregnancies. Results of the study reveal that the lower birth weight among African-American neonates is due to lean body mass and not because of difference in adiposity.

OBJECTIVE -- To determine if glucose and C-peptide values obtained as part of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study could be used to estimate insulin sensitivity during late pregnancy. RESEARCH DESIGN AND METHODS -- A total of 78 women enrolled in the HAPO study were recruited for this ancillary study. Venous plasma samples were drawn after an 8- to 10-h fast (time 0) and at 30, 60, 90, and 120 rain after a 75-g glucose challenge, which was performed at 24-32 weeks' gestation. Samples were analyzed for plasma glucose, insulin, and C-peptide. Insulin sensitivity was estimated using the established Matsuda and DeFronzo insulin sensitivity index for oral glucose tolerance tests (IS[sub OGTT]). Insulin sensitivity was also calculated from two other commonly used indexes of insulin sensitivity (that for homeostasis model assessment [IS[sub HOMA]] and that for quantitative insulin sensitivity check index [IS[sub QUICKI]]). A new insulin sensitivity index was calculated using the glucose and C-peptide concentrations at 0 and 60 min to derive IS[sub HOMA C-pep], IS[sub QUICKI C-pep], and IS[sub OGTT C-pep]. These indexes were then correlated with insulin sensitivity estimated from the IS[sub OGTT]. RESULTS -- The strongest correlation with the IS[sub OGTT] was obtained for IS[sub OGTT C-pep] (r = 0.792, P < 0.001). Further, the correlations of IS[sub HOMA C-pep] and IS[sub QUICKI C-pep] with IS[sub OGTT] were also significant (r = 0.676, P < 0.001 and r = 0.707, P < 0.001, respectively). CONCLUSIONS -- These data suggest that calculated IS[sub OGTT C-pep] is an excellent predictor of insulin sensitivity in pregnancy and can be used to estimate insulin sensitivity in over 25,000 women participating in the HAPO study. [ABSTRACT FROM AUTHOR]

OBJECTIVE -- The objective of this study was to determine maternal hormonal and metabolic factors associated with insulin sensitivity in human pregnancy. RESEARCH DESIGN AND METHODS-- This was a prospective observational cross-sectional study of 180 normal pregnant women, using samples collected at the time of a blinded oral glucose tolerance test (OGTT) between 24 and 32 weeks' gestation as an ancillary to the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. The study was conducted at two public university teaching hospitals, Cleveland, Ohio, and Brisbane, Australia. Fasting maternal serum cholesterol, triglycerides, free fatty acids, insulin, leptin, tumor necrosis factor-α, placental growth hormone (PGH), insulin-like growth factors (IGFs) 1 and 2, and insulin-like growth factor binding proteins (IGFBPs) 1 and 3 were assayed. Correlation and multiple regression analyses were used to determine factors associated with maternal insulin sensitivity (IS) estimated using both OGTT-derived (IS[sub OGTT]) and fasting (using the homeostasis model assessment [HOMA]; IS[sub HOMA]) insulin and glucose concentrations. RESULTS -- Insulin sensitivity correlated (r = x and y for IS[sub OGTT] and IS[sub HOMA], a respectively) with fasting maternal serum leptin (-0.44 and -0.52), IGFBP1 (0.42 and 0.39), and triglycerides (-0.31 and -0.27). These factors were significantly associated with insulin sensitivity in multiple regression analyses (adjusted R² 0.44 for IS[sub OGTT] and IS[sub HOMA]). These variables explained more than 40% of the variance in estimates of insulin sensitivity. CONCLUSIONS-- Maternal hormonal and metabolic factors related to the placenta, adipose tissue, and the growth hormone axis are associated with the variation in insulin sensitivity seen during normal human pregnancy. [ABSTRACT FROM AUTHOR]

Nonsyndromic mental retardation is one of the most important unresolved problems in genetic health care. Autosomal forms are far more common than X-linked forms, but, in contrast to the latter, they are still largely unexplored. Here, we report a complex mutation in the ionotropic glutamate receptor 6 gene (GRIK2, also called ‘GLUR6’) that cosegregates with moderate-to-severe nonsyndromic autosomal recessive mental retardation in a large, consanguineous Iranian family. The predicted gene product lacks the first ligand-binding domain, the adjacent transmembrane domain, and the putative pore loop, suggesting a complete loss of function of the GLUK6 protein, which is supported by electrophysiological data. This finding provides the first proof that GLUK6 is indispensable for higher brain functions in humans, and future studies of this and other ionotropic kainate receptors will shed more light on the pathophysiology of mental retardation. [ABSTRACT FROM AUTHOR]

The article focuses on the phenotype of infants of mothers with gestational diabetes mellitus (GDM). The independent effect of maternal pregravid obesity on fetal adiposity in the infant of the GDM mother is discussed. It emphasizes that rational treatment modalities will be developed through better understanding of the various maternal components and factors relating to growth in the infants.

Background: The RET proto-oncogene encodes a protein that belongs to the tyrosine kinase growth factor receptor family. Germline point mutations in RET are found in individuals with multiple endocrine neoplasia (MEN) syndromes, and gene rearrangements have been reported in papillary thyroid cancers. We recently identified transcripts of the RET proto-oncogene in human prostate cancer xenografts and prostate cancer cell lines by means of reverse transcription-polymerase chain reaction analyses. The purpose of this study was to investigate Ret protein expression in human prostate tissue.Methods: Ret protein expression was evaluated immunohistochemically in formalin-fixed, paraffin-embedded whole-prostate sections. The prostate specimens were obtained from 30 patients with prostate cancer after radical prostatectomies. Ret protein expression was compared in tumor foci and benign prostatic tissue. Medullary thyroid carcinoma tissue associated with an MEN syndrome and papillary thyroid cancer tissue served as positive controls.Results: Ret appeared to be overexpressed in high-grade (histopathologically advanced) prostatic intraepithelial neoplasia (PIN) and prostate cancer when compared with its expression level in benign prostatic secretory epithelium. In addition, there was an apparent increase in Ret protein expression with decreased cellular differentiation, i.e., increasing Gleason pattern.Conclusion: Expression of the RET proto-oncogene in benign prostatic epithelium, high-grade PIN, and histopathologically advanced prostate cancer suggests that RET may play a role in the growth of both benign and neoplastic prostate epithelial cells. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the longitudinal changes in body composition of infants of women with NGT and GDM during the first year of life. We evaluated 192 infants (93 NGT, 99 GDM) from birth and again at 4 (n=130), 8 (n=138) and 12 (n=112) months of age, using total body electrical conductivity. The changes in body composition over time we evaluated by estimating the slope of each subject's follow-up (follow-up visits n=l-3) after birth and comparing the 2 groups using parametric ANOVA and ANCOVA. At birth there was no significant difference in weight (3258 ±516 vs. 3356 ±491 g, p=0.18) or lean body mass (LBM) (2930 ±385 vs. 2929 ±368g, p=0.99) but there was significantly greater fat mass (FM) and % body fat (%BF) in the infants of the GDM (328 ±183 vs. 426 ± 195g, p=0.004) and (9.6 ±4.4 vs. 12.3 ±4.5%, p=0.0001). At 4 and 8 months there was no significant difference in the increase in mean adjusted follow-up weight or LBM between groups. At 4 and 8 months there was significantly less increase in FM (p=0.03 and 0.05) and % BF (p=0.0003 and p=0.003) in the GDM vs. the NGT group. At 12 months the only significant difference between the groups was that the infants of the GDM had significantly less %BF compared with the NGT (14.9 ±7.0 vs. 17.9 ±5.4%, p=0.01). Overall there was an increase in weight (6527 ±968 vs. 6288 ±1174g, p=0.02), FM (2407 ±609 vs. 2233 ±781 g, p=0.0009) and %BF (17.9 ±5.5 vs. 15.0 ±6.9%, p=0.0001) but not LBM (4120 ±570 vs. 4054 ±544g, p=0.60) in the NGT vs. the GDM offspring during the entire period of study. These changes in FM and %BF over time were not altered after adjusting for ethnicity, smoking, breastfeeding or maternal education. We conclude that although the infants of the GDM have increased adiposity at birth, by 1 year of age, the infants of the NGT have gained greater weight because of an increase in FM but not LBM mass. [ABSTRACT FROM AUTHOR]