Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Negative Thermal Expansion Induced in Tri-graphene and T‑graphene by the Rigid-Unit Modes

Materials which contract on heating (negative thermal expansion, NTE) are of significant interest for advanced applications. Graphene has shown NTE up to 1000 K, which motivates further improvements in two-dimensional carbon to attain superior performance. In this Communication, very large negative thermal expansion coefficients (αT) are reported for tri-graphene (TrG) and T-graphene (TG). Quasi-harmonic approximation calculations show that αT remains negative until 4200 K and 2900 K for TrG and TG, respectively. The high NTE for these systems is understood on the basis of the soft phonon modes, which induce rotation of the 3-membered and the 4-membered rings in TrG and TG, respectively, and ab initio molecular dynamics simulations. The local distortions for the 3–12 rings (in TrG) and 4–8 rings (in TG) have structural resemblance with the rigid-unit modes that are usually envisioned for bulk systems

Maleic Anhydride Grafted Atactic Polypropylene As Exciting New Compatibilizer for poly(Ethylene-co-Octene) Organically Modified Clay Nanocomposites: Investigations on Mechanical and Rheological Properties

This is probably the first report on maleic anhydride (MA) grafted atactic polypropylene (aPP) acting as a typical compatibilizer for synthesis of poly­(ethylene-co-octene) (POE) organically modified montmorillonite (OMMT) nanocomposites. The maximally grafted aPP (93.67% with 3 wt % MA) was used for compatibilization. OMMT concentrations were varied as 1, 3, and 5 wt % with respect to POE. Only moderate improvements in mechanical and rheological properties were recorded in both uncompatibilized (POE–OMMT) and compatibilized (POE–OMMT–1 wt % compatibilizer) nanocomposites due to predominant aggregation of OMMT layers. However, at higher compatibilizer content, e.g. 3 and 5 wt %, similar properties were hugely improved (92% rise in tensile strength, 55% rise in net elongation, etc.) due to partial delamination of OMMT galleries. Better processability including reduced die swell and flow activation energy and smoother extrudate profiles were also obtained as additional benefits at those compositions due to orientation of the delaminated OMMT layers in the flow direction

Distribution of socio-demographic, behavioral factors and HIV sero-status among MSM attending HIV sentinel sites in West Bengal, 2010–11 (N = 1237).

<p>^a Category excludes missing values</p><p>^b Panthi: Self-identified subgroup of MSM who are externally more masculine, and usually play the insertive partner’s role during anal intercourse with another MSM¹⁴</p><p>^cDouble decker: Self-identified subgroup of MSM whose gender identity is often neutral and dependant on the identity of their partner, hence they get engaged in both (insertive as well as receptive) roles during anal intercourse with another MSM¹⁴</p><p>^dKothi: Self-identified subgroup of MSM who are more effeminate and commonly play the receptive role during anal intercourse with another MSM¹⁴</p><p>Distribution of socio-demographic, behavioral factors and HIV sero-status among MSM attending HIV sentinel sites in West Bengal, 2010–11 (N = 1237).</p

Unadjusted and adjusted^a association (using saturated model) of socio-demographic and behavioral characteristics with HIV sero-positivity among MSM attending HIV sentinel sites in West Bengal, 2010–11 (N = 1237).

<p>^a Each socio-demographic and behavioral characteristic adjusted for all others.</p><p>^b CL: confidence limits</p><p>* p value indicates statistically significant association with HIV sero-positivity at α = 0.05</p><p>Unadjusted and adjusted<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127232#t002fn001" target="_blank">^a</a> association (using saturated model) of socio-demographic and behavioral characteristics with HIV sero-positivity among MSM attending HIV sentinel sites in West Bengal, 2010–11 (N = 1237).</p