An assessment of the causes of the errors in the 2015 UK General Election opinion polls

The opinion polls undertaken prior to the 2015 UK General Election under-estimated the Conservative lead over Labour by an average of 7 percentage points. This collective failure led politicians and commentators to question the validity and utility of political polling and raised concerns regarding a broader public loss of confidence in survey research. In this paper, we assess the likely causes of the 2015 polling errors. We begin by setting out a formal account of the statistical methodology and assumptions required for valid estimation of party vote shares using quota sampling. We then describe the current approach of polling organisations for estimating sampling variability and suggest a new method based on bootstrap re-sampling. Next, we use poll micro-data to assess the plausibility of different explanations of the polling errors. Our conclusion is that the primary cause of the polling errors in 2015 was unrepresentative sampling

Preparation of Hierarchically Porous Metal–Organic Frameworks <i>via</i> Slow Chemical Vapor Etching for CO₂ Cycloaddition

Hierarchically porous metal–organic frameworks (HP-MOFs) are a class of promising functional material with micropores, mesopores, and/or macropores, which can address the issue of slow mass transfer and less exposed active sites for primitive microporous MOFs. Despite many attempts that have been achieved through a variety of techniques to date, there is still a myriad of spaces that urgently need to be exploited. In this work, we report the novel synthesis of HP-MOFs via slow chemical steam etching. The preparation process can be subtly achieved using water vapor as an etchant; meanwhile, the addition of ethanol into the vapor atmosphere is carried out because it can stabilize the MOF framework well with its hydrophobic alkane tails, thereby slowing the etching rate toward MOFs, successfully realizing the controllable etching manner of MOF components. Furthermore, the joint influence of the water content and etching temperature on the MOF backbone structure etched has thus been investigated in detail. Impressively, we can harvest desired HP-MOFs with the retained crystalline structure at a water content of 50% and an etching temperature of 120 °C. The resulting HK-120/50 product etched exhibits excellent catalytic activity and stability in [2 + 3] cycloaddition of CO2 than pristine MOF, which can be attributed to the more exposure of active sites and the acceleration of mass transportation across the entire MOF skeleton. Noteworthy, the strategy proposed in this study may be extended to other HP-MOF construction systems due to the lability of most MOFs toward the chemical water vapor

Piezothermic Transduction of Functional Composite Materials

Conveyances of physical energies (such as force, heat, and electricity) from one to another exist in nature and have initiated manifold useful applications. Piezothermic transduction refers to a change in the thermal conduction of a material when a mechanical strain is applied, which can be applied in high-performance pressure sensing and smart energy control. Here, we propose the piezothermic concept and investigate the mechanism of its transduction in three functional composite materials, that is, particle-reinforced composites, porous materials, and series-model materials. Theoretical models for analyzing relatedness effects of material properties (e.g., thermal conductivity, Young’s modulus, and volume fraction) are established and validated by both finite element analyses and experimental measurements. The piezothermic transduction provides novel and promising strategies to implement high-performance mechanical sensing as well as energy control through optimizing composite materials. As a demonstration, a pressure sensor with a super high range-to-limit ratio of 50 000 that has a lower detection limit of 3.9 Pa and a large measurement range of 200 kPa is developed

DataSheet3_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

Comonomer-Tuned Gel Electrolyte Enables Ultralong Cycle Life of Solid-State Lithium Metal Batteries

Rechargeable lithium metal batteries (LMBs) are considered the “holy grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries has prevented their practical applications. The benefits of solid-state electrolyte for LMBs are limited due to the common compromise between ionic conductivity and mechanical property. This work proposes a mechanism for simultaneous improvement in ionic conductivity and mechanical strength of gel polymer electrolyte (GPE) which is based on tunable cross-linked polymer network through adjusting monomer ratios. With increasing bisphenol A ethoxylate dimethacrylate (E2BADMA) and poly(ethylene glycol) diacrylate (PEGDA) mass ratios in GPE precursors, the formed polymer network experienced a composition evolution from a 3D cross-linked mono PEGDA network to triple PEGDA, E2BADMA, and PEGDA/E2BADMA networks and then to dual E2BADMA and PEGDA/E2BADMA networks, accompanied by the increase in both storage modulus (from 6 to 37 MPa) and ionic conductivity (from 0.06 to 0.44 mS cm–1). As a result, the E2BADMA/PEGDA mass ratio of 2:1 facilitates the successful fabrication of a dual-network-supported GPE (PEEPL-12) with a mechanical strength of 37 MPa and superior electrochemical properties (a high ionic conductivity of 0.44 mS cm–1 and a wide electrochemical stability window of 4.85 V vs Li/Li+). Such polymer electrolyte-based symmetric lithium metal batteries delivered a long cycle life (2000 h at 0.1 mA cm–2 and 0.1 mAh cm–2), and the Li|PEEPL-12|LiFePO4 cell delivered a high capacity of 140 mAh g–1 at the 100th cycle at the current density of 0.1 C (1 C = 170 mAh g–1). A more thorough investigation indicated the formation of a stable solid electrolyte interphase layer on a lithium metal anode. These extraordinary features open up a venue for fabrication of advanced polymer electrolyte for long-cycle-life lithium metal batteries

DataSheet4_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

Comonomer-Tuned Gel Electrolyte Enables Ultralong Cycle Life of Solid-State Lithium Metal Batteries

Rechargeable lithium metal batteries (LMBs) are considered the “holy grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries has prevented their practical applications. The benefits of solid-state electrolyte for LMBs are limited due to the common compromise between ionic conductivity and mechanical property. This work proposes a mechanism for simultaneous improvement in ionic conductivity and mechanical strength of gel polymer electrolyte (GPE) which is based on tunable cross-linked polymer network through adjusting monomer ratios. With increasing bisphenol A ethoxylate dimethacrylate (E2BADMA) and poly(ethylene glycol) diacrylate (PEGDA) mass ratios in GPE precursors, the formed polymer network experienced a composition evolution from a 3D cross-linked mono PEGDA network to triple PEGDA, E2BADMA, and PEGDA/E2BADMA networks and then to dual E2BADMA and PEGDA/E2BADMA networks, accompanied by the increase in both storage modulus (from 6 to 37 MPa) and ionic conductivity (from 0.06 to 0.44 mS cm–1). As a result, the E2BADMA/PEGDA mass ratio of 2:1 facilitates the successful fabrication of a dual-network-supported GPE (PEEPL-12) with a mechanical strength of 37 MPa and superior electrochemical properties (a high ionic conductivity of 0.44 mS cm–1 and a wide electrochemical stability window of 4.85 V vs Li/Li+). Such polymer electrolyte-based symmetric lithium metal batteries delivered a long cycle life (2000 h at 0.1 mA cm–2 and 0.1 mAh cm–2), and the Li|PEEPL-12|LiFePO4 cell delivered a high capacity of 140 mAh g–1 at the 100th cycle at the current density of 0.1 C (1 C = 170 mAh g–1). A more thorough investigation indicated the formation of a stable solid electrolyte interphase layer on a lithium metal anode. These extraordinary features open up a venue for fabrication of advanced polymer electrolyte for long-cycle-life lithium metal batteries

DataSheet2_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

Manipulating Dispersion and Distribution of Graphene in PLA through Novel Interface Engineering for Improved Conductive Properties

This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (<i>f</i>-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ionic liquid. Ethylene/<i>n</i>-butyl acrylate/glycidyl methacrylate terpolymer elastomer (EBA-GMA) was introduced as the minor phase to tailor the interface of matrix/graphene through reactive compatibilization. GO particles were predominantly dispersed in PLA in a self-agglomerating pattern, while <i>f</i>-GO was preferentially located in the introduced rubber phase or at the PLA/EBA-GMA interfaces through the formation of the three-dimensional percolated structures, especially for these functionalized graphene with reactive groups. The selective localization of the <i>f</i>-GO also played a crucial role in stabilizing and improving the phase morphology of the PLA blend through reducing the interfacial tension between two phases. The establishment of the percolated network structures in the ternary system was responsible for the improved AC conductivity and better dielectric properties of the resulting nanocomposites

Comonomer-Tuned Gel Electrolyte Enables Ultralong Cycle Life of Solid-State Lithium Metal Batteries

Rechargeable lithium metal batteries (LMBs) are considered the “holy grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries has prevented their practical applications. The benefits of solid-state electrolyte for LMBs are limited due to the common compromise between ionic conductivity and mechanical property. This work proposes a mechanism for simultaneous improvement in ionic conductivity and mechanical strength of gel polymer electrolyte (GPE) which is based on tunable cross-linked polymer network through adjusting monomer ratios. With increasing bisphenol A ethoxylate dimethacrylate (E2BADMA) and poly(ethylene glycol) diacrylate (PEGDA) mass ratios in GPE precursors, the formed polymer network experienced a composition evolution from a 3D cross-linked mono PEGDA network to triple PEGDA, E2BADMA, and PEGDA/E2BADMA networks and then to dual E2BADMA and PEGDA/E2BADMA networks, accompanied by the increase in both storage modulus (from 6 to 37 MPa) and ionic conductivity (from 0.06 to 0.44 mS cm–1). As a result, the E2BADMA/PEGDA mass ratio of 2:1 facilitates the successful fabrication of a dual-network-supported GPE (PEEPL-12) with a mechanical strength of 37 MPa and superior electrochemical properties (a high ionic conductivity of 0.44 mS cm–1 and a wide electrochemical stability window of 4.85 V vs Li/Li+). Such polymer electrolyte-based symmetric lithium metal batteries delivered a long cycle life (2000 h at 0.1 mA cm–2 and 0.1 mAh cm–2), and the Li|PEEPL-12|LiFePO4 cell delivered a high capacity of 140 mAh g–1 at the 100th cycle at the current density of 0.1 C (1 C = 170 mAh g–1). A more thorough investigation indicated the formation of a stable solid electrolyte interphase layer on a lithium metal anode. These extraordinary features open up a venue for fabrication of advanced polymer electrolyte for long-cycle-life lithium metal batteries