Two-dimensional (2D) Dion-Jacobson (D-J)-type cesium lead iodide CsPbI ₃ perform remarkably in terms of stability. However, the complex interactions between spacer and inorganic layers limit its excellent progress in perovskite solar cells (PSCs). Herein, starting from the considerable structural diversity of organic spacers, we engineer 2D CsPbI ₃ with fine-tuning functionalities. Specifically, for the first time we embedded fluorinated aromatic cations in 2D D-J CsPbI ₃, and successfully applied it into construction of high-performance PSCs. Compared with constitutive 1,4-diaminobenzene (PDA), the fluorinated 2-fluorobenzene-1,4-diamine (F-PDA) component greatly expands the dipole moment from 0.59D to 3.47D, which reduces the exciton binding energy of the system. A theoretical study shows that the spacer layer and inorganic plane are more enriched with charge accumulation in (F-PDA)Cs _{n– 1}Pb _nI _{3 n+ 1}. The results show that (F-PDA)Cs _{n– 1}Pb _nI _{3 n+ 1} demonstrates more significant charge transfer between organic and inorganic layers than (PDA)Cs _{n– 1}Pb _nI _{3 n+ 1}, and it is confirmed in the femtosecond transient absorption experiment. Moreover, the interactions of the fluorinated spacer with the [PbI ₆] ^{4 –} plane effectively manipulate the crystallization quality, and thus the ion migration and defect formation of target 2D CsPbI ₃ are inhibited. As a result, we obtained a record power conversion efficiency (PCE) beyond 15% for 2D D-J (F-PDA)Cs ₃Pb ₄I ₁₃ (n = 4) PSCs with significantly improved environmental stability compared with the three-dimensional (3D) counterparts.

The SPICA-SAFARI instrument requires extremely sensitive transition edge sensor (TES) arrays with a noise equivalent power of 2×10-19W/Hz and a readout system with an output noise that is dominated by the detector noise. It is essential to ensure the frequency domain multiplexing (FDM) readout system in SAFARI meets the noise requirement. The FDM system in SAFARI consists essentially of LC filters, a superconducting quantum interference device, a room-temperature low-noise amplifier (LNA), and a demultiplexer. Here we present a noise study of the LNA from a laboratory amplifier chain. We found the equivalent current and voltage noise of the LNA to be 5.4pA/Hz and 315pV/Hz, respectively, which are low enough to read out SAFARI’s TES arrays.

Optimized stent pattern design can effectively enhance the mechanical performance of magnesium alloy stents by adjusting strain distribution and evolution during stent deformation, thereby overcoming the limitations imposed by the intrinsic mechanical properties of magnesium alloys. In the present study, a new stent design pattern for magnesium alloys was proposed and compared to two existing stent design patterns. Measures of the mechanical performance of these three stents, including crimping and expanding deformability, radial scaffolding capacity, radial recoil and bending flexibility, were determined. Three-dimensional finite element (FE) models were built to predict the mechanical performance of the stents with the three design patterns and to assist in understanding the experimental results. The results showed that, overall, the stent with the new design pattern was superior to the stents based on the existing designs, though the expanding capacity of the newly designed stent still needed to be improved.

As energy costs become increasingly greater contributors to a cloud provider's overall costs, it is important for the cloud to recoup these energy costs from its tenants for profitability via appropriate pricing design. The poor predictability of real-world tenants' demand and demand responses (DRs) make such pricing design a challenging problem. We formulate a leader-follower game-based cloud pricing framework with the goal of maximizing cloud's profit. The key distinguishing aspect of our approach is our emphasis on modeling both the cloud and its tenants as working with low predictability in their inputs. Consequently, we model them as employing myopic control with short-term predictive models. Our empirical evaluation using tenant trace from IBM production data centers shows that (i) cloud's profit and VM prices are sensitive to the tradeoffs between its energy costs, tenant's demand and DR, and (ii) the cloud's estimation of tenants' demands/DR may significantly affect its profitability.