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

DataSheet2_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

DataSheet1_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

DataSheet5_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

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

Graphical Abstract</p

DataSheet6_Electrophoretic-deposited MXene titanium coatings in regulating bacteria and cell response for peri-implantitis.ZIP

Graphical Abstract</p

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

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