Energy Reduction Effect Research Articles

Effects of hydrogen and specimen thickness on fracture toughness of ferritic steel welded joint

In this study, fracture behaviors of base metal and weld metal of ferritic steel welded joint in the thick wall pipeline for hydrogen transportation were investigated and the effects of hydrogen and specimen thickness (B) on fracture toughness were comprehensively considered in detail. A series of single edge notched tensile (SENT) tests for base metal and weld metal with B/W (width) ratio of 0.5, 1 and 2 were conducted with and without pre-electrochemical hydrogen charging, and crack tip opening displacement (CTOD) of δm value was obtained by the double clip gauges method. It was found that fracture toughness (δm) of base metal and weld metal decreased with increasing specimen thickness or hydrogenating, and δm of hydrogenating specimen with B/W ratio of 2 was smallest. It was believed that large specimen thickness decreased fracture toughness by constraining plastic deformation at crack tip and restricting dislocations movement, while hydrogen promoted embrittlement by reducing cohesive energy of fracture. In the hydrogenating specimen with larger thickness, there was lower dislocation density near crack tip, leading to a decrease in trapped hydrogen and intensifying the cohesive energy reduction effect, which resulted in reduced δm and the worse fracture toughness, and it means that hydrogen and specimen thickness synergistically affected fracture toughness. In addition, effect of thickness and hydrogen on decreasing fracture toughness was more pronounced for weld metal than base metal, which could be attributed to poorer plastic deformation ability of weld metal and lower dislocation density at crack tip. It is concluded that the hydrogen and thickness effects should be taken into account for the structural integrity evaluation of welded joint in hydrogen transportation pipeline.

Effect of Ga on the microstructure and properties of NiCoV alloy at different annealing temperatures

To obtain a high-entropy alloy characterized by high strength and plasticity, (NiCoV)100-xGax (x ​= ​0, 5, 7) was successfully prepared, cold-rolled, and heat-treated. The microstructure was analyzed to correlate Ga content with the performance of the system. The addition of Ga can produce alloying effects, including solid solution strengthening effect, second phase precipitation strengthening effect, and layer misalignment energy reduction effect. The experimental results show adding Ga elements can enrich Ni, Co, V, and Ga above the grain boundaries, causing the alloy to produce annealed twins inside. The alloy is strengthened mainly by precipitation, and the formation of the precipitation phase effectively enhances the strength of the alloy. The low stacking fault energy promotes the toughening of NiCoV but makes the plasticity of the alloy decrease. Still, the formation of annealed twins effectively increases the plasticity, which makes the alloy harder but does not reduce the plasticity too much. By comparing the experimental properties, (NiCoV)93Ga7 showed the best mechanical properties at the annealing temperature of 900 ​°C, yield strength, tensile strength and elongation of 906 ​MPa, 1321 ​MPa and 21.36 ​%, respectively.

Input Energy Reduction‐Oriented Control and Analytical Design of Inerter‐Enabled Isolators for Large‐Span Structures

Seismic isolation technologies for large‐span structures have rapidly developed alongside the popularization of the seismic resilience concept. To produce a high‐efficiency isolation technology with lower energy dissipation demands, this paper proposes a novel inerter‐enabled isolator (IeI) and a tailored input energy reduction‐oriented design method. The inerter‐based damper within the IeI is developed by combining the dashpot, tuning spring, and two inerters to facilitate the optimization of inerter distribution. Assuming the large‐span structure remains linear, the overall seismic input energy of the large‐span structure with IeIs and its allocation in the superstructure and additional damping are quantified using stochastic energy analysis. The advantages of the IeI over the conventional linear viscous damper (LVD) isolator are elucidated through dimensionless parametric analysis. Based on the results of parametric analysis, an input energy reduction‐oriented design method is proposed for the IeI, along with an easy‐to‐follow diagram that helps with preliminary design in practical applications. The effectiveness of the IeI and the proposed design method is validated through a design case study of a benchmark large‐span structure. The results demonstrate that the IeI reduces the seismic response of large‐span structures by simultaneously employing the input energy reduction effect of grounded inerters with the damping‐enhancing effect of inerter‐based dampers. The proposed design method effectively balances the performance of controlling the large‐span structure and the isolator displacement. Under consistent control performance and isolator displacement constraints, the IeI requires much less damping coefficient and energy dissipation capacity than the conventional LVD isolator. Moreover, leveraging the damping enhancement and input energy reduction effects, the IeI achieves comparable control performance to the conventional LVD isolator, even under stricter isolator displacement constraints.

Analysis of Energy Reduction and Energy Self-Sufficiency Improvement Effects by Applying a Bidirectional Reflectance PV Array with Integrated External Shading at a School Building

In South Korea, the introduction of new and renewable energy in the building sector has been promoted through various policies since the early 2000s. As a result, solar photovoltaics (PV), which are mostly applied to the rooftops of buildings, and building-integrated photovoltaics (BIPV), which are installed on the elevated surfaces of buildings, have been applied to various sites with subsidies. Renewable energy will be mandatory for all buildings from 2025. In general, the power generation efficiency of PV panels varies depending on the installation angle. According to Korean standards, the power generation efficiency is 100% for an installation on a 30° slope, 90% for a horizontal installation, and 70% for a vertical installation. This study proposes a BIPV that improves the power generation efficiency using the unique reflectance of PV panel surfaces made of glass and a bidirectional reflectance PV array. This new type of BIPV structure improves the power generation efficiency and reduces the solar heat gain coefficient (SHGC) as it protrudes over the windows, providing external shading. It is defined as bidirectional reflectance PV (BRPV), and its performance is evaluated. The effects of applying BRPVs (48 KW by 160 PV Panels with 300 W) to a school building with a fixed slope PV on the rooftop were calculated based on annual measurement results, and it was found that the energy independence rate of the building increased from 34.1 to 65.8%.

Advantages and design of inerters for isolated storage tanks incorporating soil conditions

Inerter-based isolation systems are effective in providing seismic protection for storage tanks. However, the vibration control-oriented mechanism of inerter-based seismic isolation systems on the seismic response of liquid storage tanks remains unclear, with designs limited to rigid base assumptions. Moreover, the objective existence of the soil-structure interaction (SSI) is overlooked. This study contributes to a discovered advantage of the inerter-based isolation system, including the reduction of input energy and precise control of specific or multiple modes of sloshing heights. Furthermore, an advantageous feature-oriented optimal design for storage tanks with an inerter-based isolation system and with the incorporation of soil conditions is proposed in this study. Initially, an analytical model is developed, considering a storage tank with multi-mode sloshing responses and representing SSIs with frequency-dependent stiffness and damping coefficients. Stochastic response analysis is performed, leading to a novel formulation of multi-mode control and an empirical power equation that quantifies the input energy reduction effect. An advantageous feature-oriented optimal design framework, in which the SSI effect, tank geometric parameters, and inerter-based isolation system parameters are implemented, is established through comprehensive parametric analysis. The results demonstrate that the inerter-based isolation system can be intentionally designed to mitigate specific modes of sloshing height, with the inerter effectively reducing the input power of the entire tank. This study emphasizes the importance of incorporating the SSI effect in the seismic analysis and optimal design of inerter-based tanks. Particularly, the inerter-based isolation system designed assuming a rigid base cannot perform as expected due to the SSI effect, significantly resulting in larger seismic responses and energy dissipation burdens. The developed optimal design method guarantees a target base shear force and sloshing height regarding the considered soil condition.

The contribution of cleaner production in the material industry to reducing embodied energy and emissions in China's building sector

Quantifying embodied energy and emissions (EEEs) can help clarify the consumption-based responsibilities of the building sector. Material consumption accounts for over 80% of the total EEEs, which is substantially affected by cleaner production measures in the material industry. Previous studies have not accurately calculated the EEEs by overlooking or oversimplifying these effects. This study aims to address this issue by making predictions about the building sector of Mainland China, which includes the floor areas of new buildings and the related material consumption between 2020 and 2035. In total, 29 cleaner production measures for steel, cement, brick, glass, and timber industries are collected. The embodied energy and CO2, SO2, NOx, and PM emissions reduction effects of the adopted measures are quantified and analysed using conservation supply curve and uncertainty analysis approaches. The results show the EEEs from material consumption will decrease by 45.9–60.7% from 2020 to 2035, to which the cleaner production measures contribute about half. The EEEs have significant spatial disparity. For example, Guangdong Province takes 2% of China's land area, but undertakes 7–9% of the domestic EEEs. The uneven distributions may cause heavy energy and environmental pressures in some provinces. The specific costs of the EEEs reductions differ by 2–4 orders of magnitude, while 30.4–34.5% and 65.5–67.8% of the embodied energy and CO2 emission reduction effects are cost-effective. This study reveals the vital role of cleaner production in EEEs reductions and provides critical insights into the green development of the building sector.

A comprehensive study on transient thermal behaviors and performances of the modular pipe-embedded energy wall system under intermittent operation conditions

The active thermal insulation technology based on utilizing low-grade thermal energy makes the opaque envelopes gradually be treated as multifunctional components with structural and energy properties. In this study, the dynamic thermal behaviors of modular pipe-embedded energy (MPE) walls integrated with pipe installation cavity and backfilling material are numerically studied, and then the impacts of key variables on MPE walls are explored. Results show that the thermal behaviors of MPE walls can be significantly improved under all intermittent charging modes, while the maximum extra heat loss caused by applying filler cavity and backfilling material is only 2.4%. When the injection time is kept constant, MPE walls operated in multi-pulse modes, especially those with higher heat injection frequency (e.g., 3On3Off mode), can achieve a better performance enhancement and operating energy reduction effect. Besides, a reasonable increase in λf-value or a:b-value can effectively alleviate the heat accumulation around water pipes. In addition, the energy consumption of heat charging systems can be significantly reduced when performance indicators can be slightly sacrificed. Results highlight the effectiveness of adding pipe cavity and backfilling materials in enhancing the performance of MPE walls, which can provide theoretical guidance and data support for such walls in the future.

A Variation-Aware MTJ Store Energy Estimation Model for Edge Devices With Verify-and-Retryable Nonvolatile Flip-Flops

While the spin-transfer torque (STT) magnetic tunnel junction (MTJ) is a promising technique for enabling nonvolatile flip-flops (NVFFs) to perform power gating to reduce leakage power without any data losses, the large store energy (the energy to make a store operation) of MTJs needs to be addressed. The nonvolatile cool mega array series is an edge-oriented coarse-grained reconfigurable accelerator that implements an improved MTJ-based NVFF with a verify-and-retryable store method that should ideally reduce the store energy under the presence of the switching time variation originating from the stochastic nature of the MTJs. However, the energy reduction effect of the method has not been formulated or evaluated thoroughly enough to make the best use of the method in actual applications. In this study, we propose an analytical model to estimate the store energy in typical operational conditions under the assumption of switching time variations following the normal distributions based on the measurements of a real chip fabricated with a 40-nm perpendicular MTJ/CMOS hybrid process. In contrast to the tedious measurement on each different condition, the proposed model allows for an instantaneous determination of the best storing method for minimizing the store energy, with an energy reduction of up to 69% compared with a conventional one-time attempt storing method. This model is expected to be used for system-level energy simulations and, ultimately, for design explorations in pursuit of energy-optimized memory.

Impact of Corporate Environmental Resource Conservation on Revenue and Equity Performance - The Moderating Effect of Black Economic Empowerment (BEE)

This paper aims to appraise the impact of energy reduction on revenue, return on equity (ROE) and adjusted headline earnings per share (aHEPS). It also aimed to assess the effect of energy reduction on revenue, ROE and aHEPS, and to examine the moderating role of black economic empowerment (BEE) on the effect of energy and water reduction on revenue, ROE and aHEPS. Secondary data from Woolworths Holdings Good Business Journey Report were analysed by using the OLS regression analysis. The results from the analysis show that energy reduction and water reduction have a significant effect on the three dependent variables namely revenue, ROA and aHEPS with a P<0.05. Furthermore, the results also show that after the BEE is introduced as a moderating independent variable, water and energy reductions show a stronger impact on revenue and aHEPS as the addition of BEE produced a stronger coefficient of correlation (R) and coefficient of determination (R²). This finding offers a practical significance to bolster corporate environmental management and financial sustainability strategy. This paper thus demonstrates that corporate attention and capacitation of previously disadvantage population through Black Economic Empowerment (BEE) has a visible short-term and long-term financial implication, which are drawn from improved corporate legitimacy, approval from the community with attendant enhanced patronage. This paper contributes to the literature by proposing a framework for understanding the moderating role of BEE on the effect of water and energy reduction on revenue, return on equity and adjusted headline earnings per share. The paper thus offers an agenda for future researchers on the accounting and financial implication of BEE performance.

An Effect of Carbon Dioxide and Energy Reduction on Production Efficiency and Economic Growth: Application of Carbon Neutrality in Korea

Global interest in climate change and carbon neutrality is hot. According to the Intergovernmental Panel on Climate Change, achieving carbon neutrality is the solution to avoiding climate change. Carbon neutrality is a global challenge for sustainable economic growth. In response, Korea declared 2050 carbon neutrality in 2021. However, for Korea to be carbon neutral, an incredible transformation in terms of an energy revolution is required. In this context, this study aims to diagnose the current situation to achieve carbon neutrality in Korea and to explore the direction of minimizing the national economic burden in the implementation process. To this end, we use the data envelopment analysis (DEA) directional distance function based on the material balance flow approach to examine changes in production efficiency and GDP due to carbon dioxide reduction and energy conversion. The empirical analysis results are as follows. First, in the analysis, according to the type of reduction, when only 1% of CO2 was reduced, GDP decreased by about 0.1%. Still, when reduced simultaneously with fossil energy, GDP fell by about 0.3% or more. Secondly, based on the scenario of the 2050 carbon-neutral plan, as a result of estimating the efficiency and GDP change caused by Korea’s energy transition, Korea is a country with a significant increase in inefficiency due to the energy transition and a substantial loss of GDP. Therefore, the government should establish a Korean carbon-neutral policy at a level that the national economy can afford.

A Deep Learning Approach toward Energy-Effective Residential Building Floor Plan Generation

The ability of deep learning has been tested to learn graphical features for building-plan generation. However, whether the deeper space allocation strategies can be obtained and thus reduce energy consumption has still not been investigated. In the present study, we aimed to train a neural network by employing a characterized sample set to generate a residential building floor plan (RBFP) for achieving energy reduction effects. The network is based on Pix2Pix, including two sub-models: functional segmentation layout (FSL) generation and building floor plan (BFP) generation. To better characterize the energy efficiency, 98 screened floor plans of Solar Decathlon (SD) entries were labeled as the sample set. The data augmentation method was adopted to improve the performance of the FSL sub-model after the preliminary testing. Three existing residential buildings were used as cases to observe whether the network-generated RBFP gained the effect of decreasing energy consumption with decent space allocation. The results showed that, under the same simulation settings and building exterior profile (BEP) conditions, the function arrangement of the generated scheme was more reasonable compared to the original scheme in each case. The annual total energy consumption was reduced by 13.38%, 12.74%, and 7.47%, respectively. In conclusion, trained by the sample set that characterizes energy efficiency, the RBFP generation network has a positive effect in both optimizing the space allocation and reducing energy consumption. The implemented data augmentation method can significantly improve the network’s training results with a small sample size.

Effects of the Installation Location of a Dielectric Barrier Discharge Plasma Actuator on the Active Passage Vortex Control of a Turbine Cascade at Low Reynolds Numbers

Because axial flow turbines are widely used as the main components of jet engines and industrial gas turbines, their energy reduction effect is significant, even with a slight performance improvement. These turbines operate over a wide range of Reynolds numbers. However, at low Reynolds numbers below 1 × 105, the aerodynamic characteristics deteriorate greatly, due to the flow separation of the boundary layer on the blade suction surface and an increase in the secondary flow. In this study, an experiment to reduce the passage vortex was conducted using a dielectric barrier discharge plasma actuator, which is expected to operate with a new innovative active flow control technology. The plasma actuator was installed on the endwall of a linear turbine cascade in the test section of a wind tunnel. From the velocity distribution measured using particle image velocimetry, the secondary flow vector, turbulence intensity, and vorticity were analyzed. The input voltage and frequency of the plasma actuator were fixed at 12 kVp-p and 10 kHz, respectively. In particular, the optimum installation location of the plasma actuator was examined from upstream to mid-passage positions of the turbine cascade (normalized axial location of Z/Cax = −0.35 to 0.51). In addition, the effect of the Reynolds number was examined by varying it between Reout = 1.8 × 104 and 3.7 × 104. From the experimental results, it was found that the optimum location of the plasma actuator was immediately before the blade leading edge (Z/Cax = −0.20 to −0.06). This is because the inlet boundary layer can be accelerated near the blade leading edge, weakening the horseshoe vortex which initially causes the passage vortex. At a higher Reynolds number, the passage vortex suppression effect of the plasma actuator is weakened, because the flow induced by the plasma actuators becomes relatively weaker as the mainstream velocity increases with an increase in the Reynolds number.

Adhesive and Hydrophobic Bilayer Hydrogel Enabled On‐Skin Biosensors for High‐Fidelity Classification of Human Emotion

AbstractTraditional human emotion recognition is based on electroencephalogram (EEG) data collection technologies which rely on plenty of rigid electrodes and lack anti‐interference, wearing comfort, and portability. Moreover, a significant distribution difference in EEG data also results in low classification accuracy. Here, on‐skin biosensors with adhesive and hydrophobic bilayer hydrogel (AHBH) as interfaces for high accuracy emotion classification are proposed. The AHBH achieves remarkable adhesion (59.7 N m−1) by combining the adhesion mechanism of catechol groups and electrostatic attraction. Meanwhile, based on the synergistic effects of hydrophobic group rearrangements and surface energy reduction, the AHB‐hydrophobic layer exhibits 133.87° water contact angles through hydrophobic treatment of only 0.5 h. Hydrogen and electrostatic bonds are also introduced to form a seamless adhesive‐hydrophobic hydrogel interface and inhibit adhesion attenuation, respectively. With the AHBH as an ideal device/skin interface, the biosensor can reliably collect high‐quality electrophysiological signals even under vibration, sweating, and long‐lasting monitoring condition. Furthermore, the on‐skin electrodes, data processing, and wireless modules are integrated into a portable headband for EEG‐based emotion classification. A domain adaptive neural network based on the transfer learning technique is introduced to alleviate the effect of domain shift and achieve high classification accuracy.

Enzyme complex addition in barley or rye broiler diets with two energy levels fed from 1 to 21 days

Two experiments were conducted to evaluate diet digestibility, performance, digestive parameters, and blood parameters when an enzyme complex (EC) was used in barley- and rye-based diets with different energy levels. In the digestibility assay (exp. I), 108 seventeen-day-old Cobb male broilers were distributed in a completely randomized design in 2 × 2 × 2 + 1 factorial arrangement with two feeds (barley or rye), two EC levels (0% and 0.02%), and two energy levels [3025 and 3125 kcal apparent metabolizable energy (AME)·kg−1], plus a control treatment. In exp. II, 1080 one-day-old Cobb male broilers were distributed in a completely randomized design in 2 × 2 × 2 + 1 factorial arrangement with two feeds (barley or rye), two EC levels (0% and 0.02%), and two energy levels (2875 and 2975 kcal AME·kg−1). No interactions were observed for any variables (exp. I and II). Enzyme complex improved the apparent metabolizable coefficient of gross energy (P = 0.0432) of diets. The EC provided greater weight gain (P = 0.0003) and better feed conversion (P = 0.0025). Intestinal viscosity at 21 d was reduced (P &lt; 0.0001) with the addition of the EC. The EC improved nutrient digestibility and performance, but the effects of energy reduction on performance could not be overcome.

Evaluation of Energy Performance and Thermal Comfort Considering the Heat Storage Capacity and Thermal Conductivity of Biocomposite Phase Change Materials

The application of phase change materials (PCMs) has been verified as an effective strategy for improving energy efficiency and reducing greenhouse gas emissions. Biocomposite PCMs (Bc-PCM) exhibit large latent heat, chemical stability, and a wide temperature range. In this study, thermal conductivity improved Bc-PCM (TBc-PCM) was made via vacuum impregnation with graphene nanoplatelets (GNPs). Chemical stability analysis and thermal performance analyses of the Bc-PCM and TBc-PCM were carried out as well as building energy simulations and thermal comfort analyses. Our results show Bc-PCM showed a higher heat storage capacity and enthalpy value compared to TBc-PCM. TBc-PCM exhibited a 378% increase in thermal conductivity compared to Bc-PCM. Building energy simulation results revealed that annual heating and cooling energy consumption decreased as the thickness of the PCM layer increased. In addition, the Bc-PCM with a larger PCM capacity was more effective in reducing energy consumption during the heating period. On the other hand, the cooling energy reduction effect was greater when TBc-PCM with high thermal conductivity was applied because of the high heat transfer during the cooling period. Thermal comfort evaluation revealed it was more comfortable when PCM was applied.

Biological Legacies and Rockfall: The Protective Effect of a Windthrown Forest

Windstorms represent one of the main large-scale disturbances that shape the European landscape and influence its forest structure, so post-event restoration activities start to gain a major role in mountainous forest management. After a disturbance event, biological legacies may enhance or maintain multiple ecosystem services of mountain forests such as protection against natural hazards, biodiversity conservation, or erosion mitigation. However, the conservation of all these ecosystem services after stand-replacing events could go against traditional management practices, such as salvage logging. Thus far, the impact of salvage logging and removal of biological legacies on the protective function of mountain stands has been poorly studied. Structural biological legacies may provide protection for natural regeneration and may also increase the terrain roughness providing a shielding effect against gravitational hazards like rockfall. The aim of this project is to understand the dynamics of post-windthrow recovery processes and to investigate how biological legacies affect the multifunctionality of mountain forests, in particular the protective function. To observe the role of biological legacies we performed 3000 simulations of rockfall activity on windthrown areas. Results show the active role of biological legacies in preventing gravitational hazards, providing a barrier effect and an energy reduction effect on rockfall activity. To conclude, we underline how forest management should take into consideration the protective function of structural legacies. A suggestion is to avoid salvage logging in order to maintain the multifunctionality of damaged stands during the recovery process.

Development of integrated technology for waste heat recovery from humid flue gas of hot water boiler

For coal-fired hot water boilers, we developed a comprehensive waste heat recovery system coupled with a packed tower, industrial steam turbine, and absorption heat pump, which can directly reduce the auxiliary power consumption, realize energy cascade utilization, and waste heat recovery. The ASPEN Plus software was used to simulate the packed tower, absorption heat pump, and industrial steam turbine system. The design parameters of the system were obtained and the operation characteristics of the system under load rates of 25%, 50%, 75%, and 100% were investigated, the feasibility of steam subsystem transformation was also analyzed. Taking a 140 MW coal-fired boiler as an example, in the range of 25%~100% load rate, the direct energy saving can reach 118 to 523 kW∙h, the waste heat recovery power is 2.7 to 11.4 MW, and the coal saving can reach 374 to 1605 kg/h, resulting in energy and resource consumption reduction effect, the system also has CO2 and pollutant emission reduction effect. The RadFrac model can be used in packed tower design, the system can work well under variable load conditions.

Mechanical Properties of Eco-Friendly and Energy-Saving Mortar with Porous Feldspar

ABSTRACTPorous feldspar is a silicate mineral that is made up of more than 80% of SiO2 and Al2O3 as components. It has a large specific surface area than sand. It has an excellent reactivity with cement as a pozzolanic component. A normal mortar as a construction material is composed of 75% of sand and 25% of cement. Carbon dioxide (CO2) is a cause of environmental pollution. It is often made when making cement contained in mortar. Therefore, it is necessary to study alternative materials that can reduce the amount of cement used. This study was conducted using feldspar as a fine aggregate instead of sand. First, feldspar was standardized through physical testing. Compressive strength tests were then carried out to compare feldspar mortar and sand-based mortar. Hydration products of mortars were confirmed using a scanning electron microscope (SEM). Result of these tests revealed that when feldspar was used, the compressive strength tended to be high. In this study, Case 3 consisting of feldspar 80% and cement 20% with reduced use of cement was found to be the most suitable one. Secondly, to confirm the appropriateness of using feldspar mortars as a floor material, thermal conductivity and thermal efficiency experiments were conducted using mortars with ingredients that differed from a normal mortar. Results of these experiments revealed that feldspar mortar was more effective as an insulating material than a normal mortar because it had lower thermal conductivity and longer heat retention time than a normal mortar. Therefore, the use of feldspar mortar could have an energy reduction effect compared to a normal mortar as a flooring material in an ondol (under-heating) type floor-heating system in Korea.

Adsorption of nitrogen at AlN(000-1) surface – Decisive role of structural and electronic factors

Adsorption of atomic and molecular nitrogen at AlN(000–1) surface was investigated by ab initio calculations and thermodynamic analysis. According to earlier works{Kempisty et al. Appl. Surf. Sci.2020, 532, 147,719} in equilibrium with Al vapor, the AlN(000–1) surface is thermodynamically stable in two states: low Al coverage θAl ≤ 1/3 ML and high Al coverageθAl ≅ 1 ML. In these two cases nitrogen adsorption is completely different. At low Al-covered surface the nitrogen atom is strongly bounded to N surface atom, creates the N2 admolecule that is finally detached leaving surface vacancy VN(s). This reaction chain energy gain is positive, ΔEDFTdet(N−N2)=3.50eV. Therefore, the atomic nitrogen present in plasma assisted molecular beam epitaxy (PA-MBE) fluxes induces the surface decay. N2 is adsorbed molecularly at the bare surface with the coverage independent energy gain about 1 eV. At the fully Al-covered surface atomic nitrogen is adsorbed in T4 sites with no barrier and large energy gain ΔEDFTads−Al(N)=8.68eV. Molecular nitrogen dissociates with the energy gain, dependent on additional N coverage: ΔEDFTads−Al(N2)=7.65eV at low and ΔEDFTads−Al(N2)=2.77eV at high, respectively. This change is related to the reduction of electron transfer contribution, caused by Fermi level shift down due to electron transfer from Al to N surface states. The thermodynamic analysis shows incomplete N coverage above the adsorbed Al layer due to the above adsorption energy reduction effect. The resulting incomplete N coverage is responsible for creation of nitrogen vacancies during AlN physical vapor transport (PVT) growth and their coalescence into Al-rich inclusions.

The joint effect of energy reduction with calcium supplementation on the risk factors of type 2 diabetes in the overweight population: a two-year randomized controlled trial

Both excessive energy intake and low calcium intake are inversely associated with the aging-related diseases, particularly for type 2 diabetes mellitus(T2DM). This study examined whether energy reduction coupled with calcium supplementation aided in the prevention of T2DM among the overweight population. A randomized controlled trial(RCT) of 1021 overweight participants was performed, in which participants were randomly assigned to 4 groups: 1) energy-reduction group(ERG), 2) calcium supplementation group(CSG), 3) energy-reduction with calcium supplementation group(ER-CSG), 4) control group(CG). Nutritional habits, anthropometric and diabetes-related indicators were measured at baseline and each follow-up time. To analyze the separate effects of dietary energy reduction and calcium supplementation, ERG and ER-CSG were integrated into ERGs. Similarly, CSG and ER-CSG were integrated into CSGs. Compared to the non-energy-reduction groups(NERGs), ERGs had lower values of ΔBMI(-0.9kg/m2), ΔFSG (-0.34mmol/L), ΔHbA1c(0.16%), and ΔHOMA-IR(-0.13), and higher value of ΔGutt index(-5.82). Compared to the non-calcium supplementation groups(NCSGs), the ΔGutt index(-5.46) in CSGs showed a significant decrease. Moreover, these risk factors for T2DM were most effectively ameliorated in ER-CSG group with the decreased values of ΔFSG(-0.42mmol/L), ΔGutt index(-0.73), and the slowest increasing rate value of Δ2h-glucose(0.37mmol/L). This RCT demonstrated that energy-reduction with calcium supplementation was a useful dietary intervention strategy for preventing the development of T2DM in the overweight population.