Autothermal Reforming of Acetic Acid to Hydrogen and Syngas on Ni and Rh Catalysts

The autothermal reforming (ATR) of acetic acid (HAc) as a model bio-oil compound is examined via bench scale experiments and equilibrium modelling to produce hydrogen and syngas. This study compares the performance of nickel (Ni-Al, Ni-CaAl) vs. rhodium (Rh-Al) for particulate packed bed (PPB), and of Rh-Al in PPB vs. Rh with and without Ceria for honeycomb monolith (‘M’) catalysts (R-M and RC-M). All PPB and M catalysts used Al2O3 as main support or washcoat, and when not pre-reduced, exhibited good performance with more than 90% of the HAc converted to C1-gases. The maximum H2 yield (6.5 wt.% of feed HAc) was obtained with both the Rh-Al and Ni-CaAl catalysts used in PPB, compared to the equilibrium limit of 7.2 wt.%, although carbon deposition from Ni-CaAl at 13.9 mg gcat−1 h−1 was significantly larger than Rh-Al’s (5.5 mg gcat−1 h−1); close to maximum H2 yields of 6.2 and 6.3 wt.% were obtained for R-M and RC-M respectively. The overall better performance of the Ni-CaAl catalyst over that of the Ni-Al was attributed to the added CaO reducing the acidity of the Al2O3 support, which provided a superior resistance to persistent coke formation. Unlike Rh-Al, the R-M and RC-M exhibited low steam conversions to H2 and CH4, evidencing little activity in water gas shift and methanation. However, the monolith catalysts showed no significant loss of activity, unlike Ni-Al. Both catalytic PPB (small reactor volumes) and monolith structures (ease of flow, strength, and stability) offer different advantages, thus Rh and Ni catalysts with new supports and structures combining these advantages for their suitability to the scale of local biomass resources could help the future sustainable use of biomasses and their bio-oils as storage friendly and energy dense sources of green hydrogen.

Black Holes as Markers of Dimensionality

Black hole temperature TBH = TP/2πd as a function of its Planck length real diameter multiplier d is derived from black hole surface gravity and Hawking temperature w.l.o.g. It is conjectured d = 1/2π describes primordial Big Bang singularity as in this case TBH = TP. A black hole interacts with the environment and observable black holes have uniquely defined Delaunay triangulations with a natural number of spherical triangles having Planck areas (bits), where a Planck triangle is active and has gravitational potential of -c2 if all its vertices have black hole gravitational potential of -c2/2 and is inactive otherwise. As temporary distribution of active triangles on an event horizon tends to maximize Shannon entropy a black hole is a fundamental, one-sided thermodynamic equilibrium limit for a dissipative structure. Black hole blackbody radiation, informational capacity fluctuations, and quantum statistics are discussed. On the basis of the latter, wavelength bounds for BE, MB, and FD statistics are derived as a function of the diameter multiplier d. It is shown that black holes feature wave-particle duality only if d ≤ 8π, which also sets the maximum diameter of a totally collapsible black hole. This outlines the program for research of other nature phenomena that emit perfect blackbody radiation, such as neutron stars and white dwarfs.

ANALISIS MODEL KEGAGALAN KONSTRUKSI RUMAH TINGGAL 2 LANTAI AKIBAT RANGKAK DI BAWAH LERENG TIMBUNAN

Construction of houses on slopes certainly has risks that can cause landslides on the slopes. One of the construction projects on slope area experienced a construction failure which caused the destruction of a 2-storey house. It is suspected that the planning of the building did not take into account the optimal rainfall. The author makes a model analysis similar to that case using a shallow foundation. The subgrade in this case is soft soil from rice fields which is then backfilled with silty clay. The soft soil beneath this embankment experiences creep, where the soil continues to move slowly even without a load. The author analyzes the settlement due to creep manually. The author also analyzes the safety factor of slope stability due to rising ground water levels. Based on the calculation results, the settlement was obtained at 14,8456 cm which is almost close to the maximum settlement limit of 15 cm. While the safety factor obtained from the application of the equilibrium limit before the rain is 1,311 but after experiencing a 5 m increase in ground water the safety factor is 1,032 which is less than 1,25.Keywords: creep, settlement, shallow foundation, slope stabilityPembangunan rumah di daerah lereng tentu memiliki risiko yang dapat menyebabkan kelongsoran pada daerah lereng. Salah satu proyek pembangunan pada suatu daerah lereng mengalami kegagalan konstruksi yang menyebabkan hancurnya rumah tinggal 2 lantai. Diduga dalam perencanaan bangunan tidak memperhitungkan curah hujan optimal. Penulis membuat analisis model yang mirip dengan kasus tersebut dengan menggunakan fondasi dangkal. Tanah dasar pada kasus ini adalah tanah lunak bekas persawahan yang kemudian di timbun dengan tanah lempung kelanauan. Tanah lunak di bawah tanah timbunan ini mengalami rangkak yang dimana tanah terus bergerak secara lambat walaupun tanpa adanya beban. Penulis menganalisis penurunan akibat dari rangkak secara manual. Penulis juga menganalisis faktor keamanan kestabilan lereng akibat dari naiknya muka air tanah. Berdasarkan hasil perhitungan, penurunan total terbesar diperoleh sebesar 14,8456 cm yang hampir mendekati batas penurunan maksimum 15 cm. Sedangkan faktor keamanan yang diperoleh dari aplikasi kesetimbangan batas sebelum hujan sebesar 1,311 tetapi setelah mengalami kenaikan muka air tanah 5 m faktor keamanannya sebesar 1,187 yang dimana faktor keamanan kurang dari 1,25.Kata kunci: rangkak, penurunan tanah, fondasi dangkal, kestabilan lereng

Formation of the BeH+ and BeD+ Molecules in Be+ + H/D Collisions Through Radiative Association

Cross sections and rate coefficients for the formation of BeH+ and BeD+ molecules in Be+ + H/D collisions through radiative association are calculated using quantum mechanical perturbation theory and Breit-Wigner theory. The local thermodynamic equilibrium limit of the molecule formation is also studied, since the process is also relevant in environments with high-density and/or strong radiation fields. The obtained rate coefficients may facilitate the kinetic modelling of BeH+/BeD+ production in astrochemical environments as well as the corrosion chemistry of thermonuclear fusion reactors.

$$X(3872)$$transport in heavy-ion collisions

The production of the $$X(3872)$$ X ( 3872 ) particle in heavy-ion collisions has been contemplated as an alternative probe of its internal structure. To investigate this conjecture, we perform transport calculations of the $$X(3872)$$ X ( 3872 ) through the fireball formed in nuclear collisions at the LHC. Within a kinetic-rate equation approach as previously used for charmonia, the formation and dissociation of the $$X(3872)$$ X ( 3872 ) is controlled by two transport parameters, i.e., its inelastic reaction rate and thermal-equilibrium limit in the evolving hot QCD medium. While the equilibrium limit is controlled by the charm production cross section in primordial nucleon-nucleon collisions (together with the spectra of charm states in the medium), the structure information is encoded in the reaction rate. We study how different scenarios for the rate affect the centrality dependence and transverse-momentum ($$p_T$$ p T ) spectra of the $$X(3872)$$ X ( 3872 ) . Larger reaction rates associated with the loosely bound molecule structure imply that it is formed later in the fireball evolution than the tetraquark and thus its final yields are generally smaller by around a factor of two, which is qualitatively different from most coalescence model calculations to date. The $$p_T$$ p T spectra provide further information as the later decoupling time within the molecular scenario leads to harder spectra caused by the blue-shift from the expanding fireball.

Heteroepitaxial van der Waals semiconductor superlattices

We report atomic layer-by-layer epitaxial growth of van der Waals (vdW) semiconductor superlattices (SLs) with programmable stacking periodicities, composed of more than two kinds of dissimilar transition-metal dichalcogenide monolayers (MLs), such as MoS2, WS2 and WSe2. The kinetics-controlled vdW epitaxy in the near equilibrium limit by metalorganic chemical vapour depositions enables to achieve accurate ML-by-ML stacking, free of interlayer atomic mixing, resulting in the tunable two-dimensional (2D) vdW electronic systems. We identified coherent atomic stacking orders at the vdW heterointerfaces, and present scaling valley polarized optical excitations that only pertain to a series of 2D type II band alignments.

String fragmentation with a time-dependent tension

Motivated by recent theoretical arguments that expanding strings can be regarded as having a temperature that is inversely proportional to the proper time, $$\tau $$ τ , we investigate the consequences of adding a term $$\propto 1/\tau $$ ∝ 1 / τ to the string tension in the Lund string-hadronization model. The lattice value for the tension, $$\kappa _0 \sim 0.18\,{\mathrm {GeV}}^2\sim 0.9\,{\mathrm {GeV}}/{\mathrm {fm}}$$ κ 0 ∼ 0.18 GeV 2 ∼ 0.9 GeV / fm , is then interpreted as the late-time/equilibrium limit. A generic prediction of this type of model is that early string breaks should be associated with higher strangeness (and baryon) fractions and higher fragmentation $$\langle p_\perp \rangle $$ ⟨ p ⊥ ⟩ values. It should be possible to use archival ee data sets to provide model-independent constraints on this type of scenario, and we propose a few simple key measurements to do so.

Plasma-Catalytic Ammonia Synthesis Beyond the Equilibrium Limit

We explore the consequences of non-thermal plasma activation on product yields in catalytic ammonia synthesis, a reaction that is equilibrium-limited at elevated temperatures. We employ a minimal microkinetic model that incorporates the influence of plasma activation on N₂ dissociation rates to predict NH₃ yields into and across the equilibrium-limited regime. NH₃ yields are predicted to exceed bulk thermodynamic equilibrium limits on materials that are thermal-rate-limited by N₂ dissociation. In all cases, yields revert to bulk equilibrium at temperatures at which thermal reaction rates exceed plasma-activated ones. Beyond-equilibrium NH₃ yields are observed in a packed bed dielectric-barrier-discharge reactor and exhibit sensitivity to catalytic material choice in a way consistent with model predictions. The approach and results highlight the opportunity to exploit synergies between non-thermal plasmas and catalysts to affect transformations at conditions inaccessible through thermal routes.