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A Tb3+ bridge can overcome the MMCT and realize the sensitization of Eu3+ ions.

Understanding the drillability indices of thermal granite under various water-cooling conditions is of great significance for deep drilling and wellbore stability during the extraction of deep geothermal energy. In this paper, we report the results of micro-drilling tests, indentation hardness tests, friction-and-wear tests as well as conventional physico–mechanical tests on thermal granite after water-cooling treatment, and the relationships between mechanical strength and drilling parameters of granite are discussed based on statistical analysis. In addition, the micro-characteristics of thermal and water-cooling defects in granite were observed via scanning electron microscopy. With increase in thermal temperature, the conventional physico–mechanical parameters and indentation hardness of thermal granite after water-cooling decreased linearly, while the average values of drilling rate, plasticity coefficient, and the mass losses of granite specimens and the grinder increased exponentially. The average P-wave velocity, uniaxial compressive strength, tensile strength and indentation hardness decreased by 84.9, 66.2, 73.3 and 66.1%, respectively, when the granite was heated to 600 °C. At 600 °C, the wellbore wall of granite collapsed during the micro-drilling tests and the friction-and-wear tests, and the average width and density of micro-cracks of thermal granite increased to 20.54 μm and 4.82 mm/mm2. The average width and density of micro-cracks in thermal granite under various water-cooling conditions developed gradually with thermal temperature, which was the main reason for the degradation in the drillability indices of granite. Strong links exist between the mechanical strength and drilling parameters of granite after water-cooling, and the drilling parameters of thermal granite can be estimated by the use of mechanical strength with given empirical equations. This study provides a theoretical basis for the geothermally accurate simulation and engineering of wellbore stability for deep hot dry rock drilling.

The bedrocks of deep geothermal reservoirs are exposed to cyclic water cooling during the exploitation of deep geothermal energy. Therefore, it is important to understand the physico-mechanical parameters of geothermal reservoir rocks. This paper reports on the P-wave velocity (Vp), uniaxial compressive strength (UCS) and elastic modulus (E) of granite specimens after exposure to different cyclic heating and water cooling treatments based on laboratory tests, and the relationships between Vp, UCS and E established through regression analysis. The physico-mechanical parameters of granite specimens all decrease remarkably in the first few thermal cycles, and their rates of decrease gradually diminish with thermal cycles, which is beneficial for the long-term exploitation of deep geothermal resources. Both UCS and E show a logarithmic correlation with Vp of granite under different high temperatures. There is a transformation from a linear relation (1 and 5 cycles) to an exponential relation (from 10 to 30 cycles) between Vp, UCS and E with thermal cycles. Such a correlation can provide a good estimation and avoid the costly, time-consuming and tedious mechanical tests. SEM observation reveals the change mechanism of the deterioration of physico-mechanical parameters, which can guide the well borehole stability during the deep geothermal energy exploitation.

Variable displacement compressor technology can achieve high steady-state efficiency, non-start/off operation thus high seasonal efficiency and capacity modulation. A comprehensive thermal-economic-environmental analysis of a household refrigerator with variable displacement compressor using three refrigerants (R134a, R152a and R1234yf) was presented using CoP and normalized CoP, set-up and running cost and Life Cycle Climate Performance, respectively. The results indicate that with the application of variable displacement technology, the compressor stroke can be tuned in response to heat load so that the power consumption is reduced thus the running cost and CO2 emissions. When the compressor stroke using R134a drops from 13 mm to 10 mm, the power consumption, total cost and life cycle CO2 emissions decrease by 86.3%, 56.7% and 59.9%, respectively. Running cost accounts for 89% of the total cost while indirect emissions accounts for 98% of the total CO2 emissions. Replacement of R134a by R152a will decrease the CoP by 10% but also reduce the cost and CO2 emissions by 5% and 8.6% respectively. This is comparable to increasing the R134a system CoP by 0.9. It is indicated that by adopting variable displacement technology, more CO2 emissions could be reduced given that part load represents over 80% of operating hours for refrigerators.

Understanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300, 400, 500 and 600 °C) was carried out to quantify the combined effects of thermal treatment and loading/unloading stress conditions on granite strength and deformation. Changes in the microstructure of granite exposed to high temperatures were revealed by optical microscopy. The experimental results indicate that both, thermal treatment and loading/unloading stress conditions, degrade the mechanical behaviors and further decrease the carrying capacity of granite. The gradual degradation of the mechanical characteristics of granite after thermal treatment is mainly associated with the evolution of thermal micro-cracks based on optical microscopy observations. The unloading stress state induces the extension of tension cracks parallel to the axial direction, and thus, the mechanical properties are degraded. Temperatures above 400 °C have a more significant influence on the mechanical characteristics of granite than the unloading treatment, whereby 400 °C can be treated as a threshold temperature for the delineation of significant deterioration. This study is expected to support feasibility and risk assessments by means of providing data for analytical calculations and numerical simulations on granite exposed to high temperatures during geothermal energy extraction.

A deep understanding of the physico-mechanical characteristics of rocks undergoing thermal treatments has gained a great interest in deep rock projects. In this research, the size and mass of cylin...

Linear compressors are very attractive for domestic refrigeration due to elimination of crank mechanism, high efficiency and compactness compared with conventional compressors. The significance of stroke control in a linear compressor not only lies in avoiding the piston collision into the cylinder head but also enabling cooling capacity modulation. Predicting piston stroke without a displacement sensor reduces the cost and facilitates the stroke control especially in miniature linear compressor where there is very limited space for installing sensors. This paper reports an artificial neural network (ANN) based stroke detection approach that can be used in linear compressors and any other linear (free-piston) machines. Experimental tests were conducted in a novel linear compressor driven refrigeration system to sample and record voltage, current and displacement. Fast Fourier transform (FFT) analysis was performed on current and voltage signals to extract harmonic terms as inputs of the neural network model to predict the stroke. Six cases with different numbers of harmonic term for current and voltage were compared. Both the mean squared errors and correlation coefficients are significantly improved with the increase of harmonic terms from one to three. However, small difference is indicated between the cases with three and six terms. Best percentage error distribution was achieved in the case with six harmonic terms with the majority of percentage errors falling within ±0.7% and a maximum percentage error of 3.5%. It can be concluded that the present ANN based stroke prediction approach can be effectively adopted for linear compressors without expensive displacement sensors. This is a key step towards the commercialization of linear refrigeration compressor technologies.

Geothermal energy is recommended as a clean and renewable energy resource. During the exploitation process, hot rocks in a geothermal reservoir will be subjected to cyclic water cooling. Laboratory tests were conducted to investigate the physical and mechanical behaviors of water-cooled granite specimens subjected to various thermal cycles with temperatures ranging from 20 °C to 500 °C. Meanwhile, scanning electron microscope (SEM) images were used to capture the development of the microcracks within the specimens. It was found that volume increases with thermal cycle and mass, that density and P wave velocity decrease with thermal cycle, especially after the first thermal cycling, and their change rates diminish with increasing thermal cycle. Both uniaxial compressive strength (UCS) and elastic modulus (E) of granite decrease with thermal cycle. The decreasing extents gradually tend to constant with thermal cycle, and they remain almost unchanged once the thermal cycle reaches 20 iterations. The deterioration mechanisms of the physical and mechanical behaviors of granite are mainly caused by the generation and propagation of microcracks. Microcrack density increases slowly with the thermal cycle rising from 10 to 30, corresponding to the decrease of the physical and mechanical properties. The results are expected to provide an important contribution to the stability of well boreholes during the exploitation of deep geothermal energy.

Laboratory tests were conducted to study the physical and mechanical properties of granite after heating and water-cooling treatment for 1 and 30 cycles from room temperature to 500 °C. The change mechanisms for the water-cooling treatment were analysed via scanning electron microscope observation. At 500 °C, the volume of granite increases by 1.73% and 2.55%, the mass decreases by 0.16% and 0.31%, and the density decreases by 1.86% and 2.78% after 1 and 30 thermal cycles, respectively. The average values of UCS and E after 1 and 30 cycles both decrease as the temperature rises, while the peak strain exhibits the reverse trend. A yield platform is observed in the yield stage of the stress–strain curve above 300 °C, and the ductility of granite gradually increases with temperature. The normalized P-wave is linear with respect to the normalized UCS and E at 1 thermal cycle, whereas it shows exponential relationships with the normalized UCS and E at 30 thermal cycles. The degradation of the physical and mechanical properties of granite after 1 and 30 cycles is mainly caused by the generation and development of microcracks inside the rock. Compared to 1 thermal cycle, more microcracks are observed at 30 thermal cycles. Therefore, the thermal cyclic treatment can further deteriorate and weaken the physical and mechanical properties of granite.

Polymer/oxide hybrid thin films, which have excellent electrical and mechanical performance, can be effectively fabricated through the sol-gel process, showing great potential in the future printed electronics. However, gelation of polymer/oxide ink systems can easily occur during a thermal process in which case capillary stress can lead to the crack of printed films due to the long period of stress accumulation. To solve this problem, the effect of different solvent systems on formed PAM/ZrO

On the basis of Lemaitre’s strain equivalence theory, the effects of high temperatures on the mechanical parameters of rock are taken into account, and a thermal damage variable DT is introduced. A statistical thermal damage constitutive model is developed by adopting the modified Mohr-Coulomb criterion with the hypothesis that the mesoscopic unit strength of rock subjected to thermal treatment obeys a Weibull random distribution. The values of the model parameters are determined by the extreme value method according to the concept of yielding. The rationality of the model is verified by comparing the calculated results with experimental results from uniaxial and conventional triaxial experiments of granite, marble, and sandstone specimens that were subjected to different high-temperature treatments. The results indicate that the model can simulate the whole process of stress-strain relations of different lithological rocks under different confined pressure and temperature conditions; the model can also reflect the characteristics of strain softening. The model does not contain any unconventional rock mechanics parameters and is lithology independent, which is highly convenient for engineering applications. This research can provide a theoretical basis for the development and protection of high-temperature rock projects.

Water has been used as a working fluid injected into the hot reservoirs during the exploitation of deep geothermal energy, therefore, understanding the thermomechanical properties of reservoir rocks after water cooling is essential. For that reason, we have conducted a series of laboratory tests on air and water cooled granites from normal temperature to 600 °C, to reveal the changes in their thermomechanical properties. At 600 °C, the average values of uniaxial compressive strength, elastic modulus and P-wave velocity of water cooled granite decrease by 84.9%, 73.1% and 66.2%, which are 11.0%, 17.0% and 17.7% larger than those of air cooled granite. Through optical microscopic analysis, the microcrack density and average width of water cooled granite increase with thermal temperature and are 4.18 mm/mm2 and 54.62 μm at 600 °C, while the values of air cooled granite are only 1.97 mm/mm2 and 25.16 μm. We thus combined the deterioration of the macroscopic mechanical characteristics of air and water cooled granites with the propagation and development of microcracks. Supported by data from international literature, the changes in the thermomechanical characteristics of granite has been systematically compared to international literature, which is hoped to provide technical support for the geothermal energy exploitation.

The involvement of oil lubricants in vapour compression refrigeration (VCR) systems could adversely influence the flow, heat transfer and efficiency of refrigeration. A numerical model for a VCR system using linear compressor, R1234yf, and POE oil is developed in this study to investigate the effect of oil lubricant on the flow and heat transfer as well as the system performance including cooling capacity and coefficient of performance (COP). The proposed model is validated by measurements of a prototype oil-free VCR system with most of the simulated data falling within ± 20 % of measurements. The evaporator heat transfer coefficient, cooling capacity, and COP for the system from the proposed model show a negative correlation with oil circulation rate (OCR). The COPs and pressure losses for oil-free system are 15-28% higher and 36-60% lower than that of oil-lubricated system respectively.

Understanding the mechanical behaviors of granite after high temperature exposure and under confining stress conditions is an important issue in deep rock engineering projects such as the mining of deep underground solid mineral resources, deep geothermal energy exploitation and deep nuclear waste repositories. In this research, conventional triaxial compression experiments were conducted on Nanan granite after thermal treatment from 200 °C to 600 °C. Based on the experimental results, the influences of pressure and temperature on the deformation and strength characteristics were analysed. The physico-mechanical change mechanisms of the heat-treated granite were revealed by optical microscopy. The test results show that under 600 °C, granite volume increases by 4.11%, whereas the mass and density decrease by 0.28% and 4.21%, respectively. Average values of triaxial compressive strength and elastic modulus, cohesion and internal friction angle all reduce with temperature, decreasing rapidly by 54.99%, 39.81%, 49.39% and 27.51% from 500 to 600 °C, respectively. Granite specimens are less brittle and have higher ductility and plasticity as the temperature increases. However, confining pressure improves the mechanical properties of granite. Optical microscope images show that microcracks in granite specimens are generated and extend gradually with temperature, causing the deterioration of the physico-mechanical behaviors of heat-treated granite.

Type 1 diabetes arises from the autoimmune destruction of insulin-producing beta-cells of the pancreas, resulting in dependence on exogenously administered insulin to maintain glucose homeostasis. In this study, our aim was to identify genetic risk factors that contribute to progression from islet autoimmunity to clinical type 1 diabetes. We analyzed 6.8 million variants derived from whole genome sequencing of 160 islet autoantibody positive subjects, including 87 who had progressed to type 1 diabetes. The Cox proportional-hazard model for survival analysis was used to identify genetic variants associated with progression. We identified one novel region, 20p12.1 (TASP1; genome-wide P –8) and three regions, 1q21.3 (MRPS21–PRPF3), 2p25.2 (NRIR), 3q22.1 (COL6A6), with suggestive evidence of association (P –8) with progression from islet autoimmunity to type 1 diabetes. Once islet autoimmunity is initiated, functional mapping identified two critical pathways, response to viral infections and interferon signaling, as contributing to disease progression. These results provide evidence that genetic pathways involved in progression from islet autoimmunity differ from those pathways identified once disease has been established. These results support the need for further investigation of genetic risk factors that modulate initiation and progression of subclinical disease to inform efforts in development of novel strategies for prediction and intervention of type 1 diabetes.

The cellular instabilities of premixed C1–C3 alkane–air mixtures were investigated at an initial temperature of 400 K and different initial pressures (0.25–1.5 MPa). Flame propagation images were recorded using high-speed Schlieren photography techniques. Cellular instabilities were analyzed using both qualitative and quantitative methods. The results showed that with an increase in the initial pressure, the flame instabilities of these three alkane–air mixtures increased as a result of the enhanced hydrodynamic instability. For a given initial pressure and with an increasing equivalence ratio, the thermal-diffusive instability was the main influencing factor on the flame instability of methane when Φ ≤ 1.0, whereas it was the result of hydrodynamic and thermal-diffusive instability when Φ > 1.0. The flame instability of ethane and propane was caused by the enhanced hydrodynamic and thermal-diffusive instability when Φ ≤ 1.0, whereas it was determined by diffusion-thermal instability when Φ > 1.0. Under the conditions with the strongest cellular instability, the cellular instability of these three alkane–air mixtures tended to increase with an increasing number of carbon atoms in the fuel.

Background: Type 1 diabetes (T1D) is determined by unknown environmental factors in genetically susceptible individuals. The design of most genome wide association studies of T1D involves comparison of cases (with varying duration of disease) with controls; hence, the genetic variants associated with T1D reflect current disease, ignoring variants that play a key role in the initiation of islet autoimmunity and the progression of subclinical disease. In this study, we focus on the genetic contribution to progression of islet autoimmunity using whole-genome sequencing in a collection of participants of the Diabetes AutoImmunity Study in the Young (DAISY). Methods: A total of 160 persistent islet autoantibody positive DAISY subjects were sequenced, including 87 subjects who progressed to T1D and 73 “non-progressors” over a mean of 11 years since seroconversion. Following whole genome sequence alignment, single nucleotide polymorphisms (SNPs) and small insertion/deletions (indels) were identified (∼6.8 million variants), and statistical analyses performed. Results: Genes with multiple SNPs associated with progression to T1D in subjects with islet autoimmunity (P < 8.5x10-8) did not overlap with known T1D risk loci; instead, four novel regions were identified - 1q21.3 (MRPS21-PRPF3), 2p25.2 (NRIR), 3q22.1 (COL6A6), and 20p12.1 (TASP1). Functional mapping of the associated SNPs within these risk loci indicates pathways critical for response to viral infections and response to interferon signaling contribute to progression to T1D once islet autoimmunity is initiated. Discussion: This study presents evidence that different genetic pathways may contribute to progression of islet autoimmunity from those identified once disease is established and support the need for follow-up studies to understand genetic risk factors that modulate progression of subclinical disease. Disclosure S. Onengut-Gumuscu: None. U. Paila: None. W. Chen: None. A. Ratan: None. Z. Zhu: None. A. Steck: None. B.I. Frohnert: None. K. Waugh: None. B. Webb-Robertson: None. J.M. Norris: None. L. Lange: None. M. Rewers: None. S.S. Rich: None.

Linear compressor is more efficient than conventional reciprocating compressor due to the absence of a crank mechanism. It can also realize capacity modulation, compactness and oil-free operation. A comprehensive numerical model of a linear compressor consisting of a thermodynamic model describing the in-cylinder pressure and temperature, a mechanical dynamics model describing movement the piston and valves and an electrical model describing the interaction of the voltage, current and back electromotive force of the linear motor was established to predict the compressor performance and to help achieve inherent capacity modulation. Experiments were conducted to validate the model using a prototype moving magnet linear compressor and remarkable accuracy is obtained. The measured and predicted piston displacement, current and shaft force agree well with the maximum error less than 10%. The predicted power factor, power consumption, stroke, mass flow rate and CoP show mean absolute percentage errors of 0.8%, 13.3%, 3.9%, 9.2% and 9.0%, respectively. As predicted, the resonant frequency can lead to lowest power consumption as well as the highest power factor and motor efficiency. At pressure ratio of 3.0, when the piston stroke increases by 1 mm, the mass flow rate increases by 0.66 g/s while the cooling capacity increases by 77.2 W. This can indicate the possibility of inherent capacity modulation.

We study the role that the global phase plays in quantum operations. Previous theoretical works suggested that the optimal (minimum) times to realize $\mathrm{SU}(n)$ quantum operations with different global phases are generally different. Here, we experimentally constructed two SU(2) operations with different global phases, i.e., $U$ and $\ensuremath{-}U$, in optimal times. Then, utilizing nuclear magnetic resonance interferometry, we measured these phases and observed the global phase's effect on the optimal times of these two operations. Our result further clarifies that the effect that the global phase has on unitary operations is not only mathematical, but also physical. In addition, this work has potential applications in many areas, such as designing time-optimal controls in quantum systems.

In this paper, a solution-processed zirconium oxide (ZrO

The initial conditions such as temperature, pressure and dilution rate can have an effect on the laminar burning velocity of natural gas. It is acknowledged that there is an equivalent effect on the laminar burning velocity between any two initial conditions. The effects of initial temperatures (323 K&ndash, 423 K), initial pressures (0.1 MPa&ndash, 0.3 MPa) and dilution rate (0&ndash, 16%, CO2 as diluent gas) on the laminar burning velocity and the flame instability were investigated at a series of equivalence ratios (0.7&ndash, 1.2) in a constant volume chamber. A chemical kinetic simulation was also conducted to calculate the laminar burning velocity and essential radicals&rsquo, concentrations under the same initial conditions. The results show that the laminar burning velocity of natural gas increases with initial temperature but decreases with initial pressure and dilution rate. The maximum concentrations of H, O and OH increase with initial temperature but decrease with initial pressure and dilution rate. Laminar burning velocity is highly correlated with the sum of the maximum concentration of H and OH.

The effect of dissociated methanol (H2:CO = 2:1 by volume) on laminar burning velocity of natural gas (methane as the main component) was studied by using a constant volume bomb (CVB). Nitrogen, as diluent gas, was added into the natural gas (CH4) - dissociated methanol (DM) mixtures to investigate the dilution effect. Experiments were conducted at initial temperature of 343 K and initial pressure of 0.3 MPa with equivalence ratios from 0.8 to 1.4. Laminar burning velocities were calculated through Schlieren photographs, correlation of in-cylinder pressure data and Chemkin-Pro. Results show an increase in laminar burning velocity with initial temperature and proportion of dissociated methanol but a decrease with initial pressure and proportion of nitrogen. The laminar burning velocities were 25.1 cm/s, 38.7 cm/s and 83.2 cm/s respectively at stoichiometric ratio when the proportions of the dissociated methanol were 0%, 40% and 80%. Adding more dissociated methanol tends to shift the peak burning velocity towards the richer side while adding nitrogen has the opposite effect. More dissociated methanol will lead to earlier cellularity.

High-fidelity quantum gates are essential for large-scale quantum computation, which can naturally be realized in a noise-resilient way. Geometric manipulation and decoherence-free subspace encoding are promising ways toward robust quantum computation. Here, by combining the advantages of both strategies, we propose and experimentally realize universal holonomic quantum gates in both a singleloop scheme and a composite scheme, based on nonadiabatic and non-Abelian geometric phases, in a decoherence-free subspace with nuclear magnetic resonance. Our experiment uses only two-body resonant spin-spin interactions and thus is experimental friendly. In particular, we also experimentally verify that the composite scheme is more robust against the pulse errors than the single-loop scheme. Therefore, our experiment provides a promising way toward faithful and robust geometric quantum manipulation., Main text has 5 pages and 4 figures. Appendix has 4 pages and 3 figures

OBJECTIVE Genetic risk scores (GRS) have been developed that differentiate individuals with type 1 diabetes from those with other forms of diabetes and are starting to be used for population screening; however, most studies were conducted in European-ancestry populations. This study identifies novel genetic variants associated with type 1 diabetes risk in African-ancestry participants and develops an African-specific GRS. RESEARCH DESIGN AND METHODS We generated single nucleotide polymorphism (SNP) data with the ImmunoChip on 1,021 African-ancestry participants with type 1 diabetes and 2,928 control participants. HLA class I and class II alleles were imputed using SNP2HLA. Logistic regression models were used to identify genome-wide significant (P < 5.0 × 10−8) SNPs associated with type 1 diabetes in the African-ancestry samples and validate SNPs associated with risk in known European-ancestry loci (P < 2.79 × 10−5). RESULTS African-specific (HLA-DQA1*03:01-HLA-DQB1*02:01) and known European-ancestry HLA haplotypes (HLA-DRB1*03:01-HLA-DQA1*05:01-HLA-DQB1*02:01, HLA-DRB1*04:01-HLA-DQA1*03:01-HLA-DQB1*03:02) were significantly associated with type 1 diabetes risk. Among European-ancestry defined non-HLA risk loci, six risk loci were significantly associated with type 1 diabetes in subjects of African ancestry. An African-specific GRS provided strong prediction of type 1 diabetes risk (area under the curve 0.871), performing significantly better than a European-based GRS and two polygenic risk scores in independent discovery and validation cohorts. CONCLUSIONS Genetic risk of type 1 diabetes includes ancestry-specific, disease-associated variants. The GRS developed here provides improved prediction of type 1 diabetes in African-ancestry subjects and a means to identify groups of individuals who would benefit from immune monitoring for early detection of islet autoimmunity.

The quality of rice bran oil (RBO) is significantly affected by its poor cold performance. The effects of the addition of tea polyphenol palmitate (TE) on the improvement of the cold performance of RBO were investigated. The results indicated that RBO remained clear at 0 °C for 5.5 h when the TE concentration was 0.08 wt%, and TE could recrystallize in RBO before RBO crystallization and further promote the nucleation of RBO crystallization. The mechanism of which TE promoted the cold performance of RBO was proposed. The partially recrystallized TE crystal could act as a nucleating agent to promote nucleation and refine crystal size. However, hydrogen bonds between the hydroxyl groups of the residual TE and the carbonyl groups of triglyceride formed which limited the movement of the RBO molecular chain and hindered the growth of the RBO crystal. Rheological and Fourier transform infrared spectroscopy experimental evidences supported this mechanism.