Oxygen‐Induced 1D to 2D Transformation of On‐Surface Organometallic Structures

While surface‐confined Ullmann‐type coupling has been widely investigated for its potential to produce π‐conjugated polymers with unique properties, the pathway of this reaction in the presence of adsorbed oxygen has yet to be explored. Here, the effect of oxygen adsorption between different steps of the polymerization reaction is studied, revealing an unexpected transformation of the 1D organometallic (OM) chains to 2D OM networks by annealing, rather than the 1D polymer obtained on pristine surfaces. Characterization by scanning tunneling microscopy and X‐ray photoelectron spectroscopy indicates that the networks consist of OM segments stabilized by chemisorbed oxygen at the vertices of the segments, as supported by density functional theory calculations. Hexagonal 2D OM networks with different sizes on Cu(111) can be created using precursors with different length, either 4,4″‐dibromo‐p‐terphenyl or 1,4‐dibromobenzene (dBB), and square networks are obtained from dBB on Cu(100). The control over size and symmetry illustrates a versatile surface patterning technique, with potential applications in confined reactions and host–guest chemistry.     

Overcoming internal barriers to industrial energy efficiency through energy audit: a case study of a large manufacturing company in the home appliances industry

Energy efficiency plays a key role in reducing global energy consumption, especially in the industrial sector, with an indirect positive impact on the competitiveness of industrial firms. Although a cultural shift toward recognizing the strategic importance of energy efficient and environmental friendly solutions is diffusing among industrial companies, also pushed by the evolution of local and international regulatory frameworks, strong barriers hampering the adoption of energy efficiency measures (EEMs) still exist. These barriers, and in particular those linked to behavioral issues, may be overcome by the use of a well-designed energy audit methodology. However, how energy audit can help overcome behavioral barriers to industrial energy efficiency remains an under-researched topic in literature. This paper presents and discusses a novel methodology for energy audit developed and implemented by a large manufacturing company. The methodology is built around four phases, and it pays special emphasis to the initial step of the audit, where the strongest resistance to the implementation of EEMs is typically found due to a lack of awareness and commitment which hampers the identification of needs and opportunities associated with the adoption of EEMs. The proposed methodology has been able to overcome in practice the typical behavioral barriers that affect the implementation of EEMs in the manufacturing sector and has strong applicability in other firms and industries.     

High-Temperature Superconductivity in a Hyperbolic Geometry of Complex Matter from Nanoscale to Mesoscopic Scale

While it was known that high-temperature superconductivity appears in cuprates showing complex multiscale phase separation due to inhomogeneous charge density wave (CDW) order, the spatial distribution of CDW domains remained an open question for a long time, because of the lack of experimental probes able to visualize their spatial distribution between atomic and macroscopic scale. Recently scanning micro-X-ray diffraction (S μXRD) revealed CDW crystalline electronic puddles with a complex fat-tailed spatial distribution of their size. In this work, we have determined and mapped the anisotropy of the CDW puddles in HgBa₂CuO₄ + y (Hg1201) single crystal. We discuss the emergence of high-temperature superconductivity in the interstitial space with hyperbolic geometry that opens a new paradigm for quantum coherence at high temperature where negative dielectric function and interference between different pathways can help to raise the critical temperature.     

MOF-Derived In2O3/CuO p-n Heterojunction Photoanode Incorporating Graphene Nanoribbons for Solar Hydrogen Generation

Solar-driven photoelectrochemical (PEC) water splitting is a promising approach toward sustainable hydrogen (H₂) generation. However, the design and synthesis of efficient semiconductor photocatalysts via a facile method remains a significant challenge, especially p-n heterojunctions based on composite metal oxides. Herein, a MOF-on-MOF (metal-organic framework) template is employed as the precursor to synthesize In₂O₃/CuO p-n heterojunction composite. After incorporation of small amounts of graphene nanoribbons (GNRs), the optimized PEC devices exhibited a maximum current density of 1.51 mA cm⁻² (at 1.6 V vs RHE) under one sun illumination (AM 1.5G, 100 mW cm⁻²), which is approximately four times higher than that of the reference device based on only In₂O₃ photoanodes. The improvement in the performance of these hybrid anodes is attributed to the presence of a p-n heterojunction that enhances the separation efficiency of photogenerated electron-hole pairs and suppresses charge recombination, as well as the presence of GNRs that can increase the conductivity by offering better path for electron transport, thus reducing the charge transfer resistance. The proposed MOF-derived In₂O₃/CuO p-n heterojunction composite is used to demonstrate a high-performance PEC device for hydrogen generation.     

The impact of the national assessment exercises on self-citation rate and publication venue: an empirical investigation on the engineering academic sector in Italy

Thelwall (J Informetr 11(1):128–151, 2017a.  https://doi.org/10.1016/j.joi.2016.12.002; Web indicators for research evaluation: a practical guide. Morgan and Claypool, London, 2017b) proposed a new family of field- and time-normalized indicators, which is intended for sparse data. These indicators are based on units of analysis (e.g., institutions) rather than on the paper level. They compare the proportion of mentioned papers (e.g., on Twitter) of a unit with the proportion of mentioned papers in the corresponding fields and publication years. We propose a new indicator (Mantel–Haenszel quotient, MHq) for the indicator family. The MHq is rooted in the Mantel–Haenszel (MH) analysis. This analysis is an established method, which can be used to pool the data from several 2?×?2 cross tables based on different subgroups. We investigate using citations and assessments by peers whether the indicator family can distinguish between quality levels defined by the assessments of peers. Thus, we test the convergent validity. We find that the MHq is able to distinguish between quality levels in most cases while other indicators of the family are not. Since our study approves the MHq as a convergent valid indicator, we apply the MHq to four different Twitter groups as defined by the company Altmetric. Our results show that there is a weak relationship between the Twitter counts of all four Twitter groups and scientific quality, much weaker than between citations and scientific quality. Therefore, our results discourage the use of Twitter counts in research evaluation.     

Anisotropic Thermal Expansion of <Emphasis Type="Italic">p</Emphasis>-Terphenyl: a Self-Assembled Supramolecular Array of Poly-<Emphasis Type="Italic">p</Emphasis>-phenyl Nanoribbons

The recent discovery of superconductivity in a metallic aromatic hydrocarbon, alkali-doped p-terphenyl, has attracted considerable interest. The critical temperature T _c ranges from few to 123 K, the record for organic superconductors, due to uncontrolled competition of multiple phases and dopants concentrations. In the proposed mechanism of Fano resonance in a superlattice of quantum wires with coexisting polarons and Fermi particles, the lattice properties play a key role. Here, we report a study of the temperature evolution of the parent compound p-terphenyl crystal structure proposed to be made of a self-assembled supramolecular network of nanoscale nanoribbons. Using temperature-dependent synchrotron X-ray diffraction, we report the anisotropic thermal expansion in the ab plane, which supports the presence of a nanoscale network of one-dimensional nanoribbons running in the b-axis direction in the P21/a structure. Below the enantiotropic phase transition at 193 K, the order parameter of the C-1 structure follows a power law behavior with the critical exponent α =?0.34 ± 0.02 and the thermal expansion of the a-axis and b-axis show major changes supporting the formation of a two-dimensional bonds network. The large temperature range of the orientation fluctuations in a double well potential of the central phenyl has been determined.     

Relation between activation energy and induction in rubber sulfur vulcanization: An experimental study

The article presents the possibility to use the so-called frequency factors in order to select the optimal temperature to mix rubber blend recipes before vulcanization without inducing premature crosslinking. As secondary result of the research, it provides a very simple approach to evaluate induction assuming a first order kinetic approach. It has been frequently observed that the activation energy in a first order rubber vulcanization scheme appears to be function of the particular activators used and that activation energy links to the so-called waiting time (and induction) by means of the frequency factor through an exponential relationship. A total of 212 rheometer curves are experimentally obtained and suitably postprocessed, consisting of pure natural rubber (NR), polybutadiene (PB), and 50–50 or 70%–30% NR-PR blends in presence of different concentrations of sulfur and accelerants (diphenyl guanidine [DPG] and N-t-butylbenzothiazole-sulfenamide [TBBS]). Data reduction is carried out to have an insight into the most suitable temperature to utilize in the different cases in order to: (a) Obtain the best mixed blends without risking premature vulcanization and (b) design the induction phase without over vulcanize the blend and/or delaying curing because the time required is too long. Waiting time and induction are evaluated by means of a well-established exponential law requiring the knowledge of the activation energy (assuming for the sake of simplicity that crosslinking occurs following a first order reaction kinetic law) and a constant called “frequency factor”. Frequency factor, considering all reactions monomolecular for the sake of simplicity, is assumed of the order of magnitude of 10⁻¹³–10⁻¹⁴ s. All experimental data carried out are critically compared and a wide explanation of the expected induction times and most suitable temperatures to use in the mixing phase is provided in the different cases considered. The article provides a meaningful insight into the importance of the link existing among activation energy, vulcanization recipe (with particular regard to concentration of accelerants, blend between two rubbers with very different activation energies and interaction between two accelerants) and mixing temperature to adopt before curing.