Phase Coexistence of Complex Fluids in Shear Flow

We present some results of recent calculations of rigid rod-like particles in shear flow, based on the Doi model. This is an ideal model system for exhibiting the generic behavior of shear-thinning fluids (polymer solutions, wormlike micelles, surfactant solutions, liquid crystals) in shear flow. We present calculations of phase coexistence under shear among weakly-aligned (paranematic) and strongly-aligned phases, including alignment in the shear plane and in the vorticity direction (log-rolling). Phase coexistence is possible, in principle, under conditions of both common shear stress and common strain rate, corresponding to different orientations of the interface between phases. We discuss arguments for resolving this degeneracy. Calculation of phase coexistence relies on the presence of inhomogeneous terms in the dynamical equations of motion, which select the appropriate pair of coexisting states. We cast this condition in terms of an equivalent dynamical system, and explore some aspects of how this differs from equilibrium phase coexistence.Comment: 16 pages, 10 figures, submitted to Faraday Discussion

Archeological Texts Show a Religious Conflict Component in the Naxos Island Revolt (499 to 494 BCE)

As revealed by later Greek records, the Naxos revolt was a socio-economic conflict between rural interests and commercial trading interests which led to the much larger Greek/Persian wars. While the socio-economic component is true, these three archaeological texts also show that the revolt was triggered by a drought and sustained by religious differences with trading interests devoted to the motion class of powers of the Ancient Pagan Paradigm and rural interests devoted to the life-growth powers represented by the crescent moon goddess Ayu (Greek: Athena, Artemis). This conflict parallels the earlier Israelite civil war triggered by the Elijah drought of 850 BCE but in that conflict the life-growth class was represented by Yahu (Yahweh) instead of Ayu. These texts reference emotion magic and deities Hu and Ayu. The language of these texts is Alphabetic Akkadian with the letter style being mostly mid-Etruscan (Sea People’s lineage) similar to that of the Etruscan Piacenza Liver (Olmsted Jan. 1, 2021). While personal Greek inscriptions were also starting to appear on funerary steles around this time, official religious texts in the Greek world continued to be written in Alphabetic Akkadian until about 440 BCE when rising Greek nationalism and military success against the Persian empire resulted in Greek replacing Akkadian as the empire language of the eastern Mediterranean

Modelling diffusion in crystals under high internal stress gradients

Diffusion of vacancies and impurities in metals is important in many processes occurring in structural materials. This diffusion often takes place in the presence of spatially rapidly varying stresses. Diffusion under stress is frequently modelled by local approximations to the vacancy formation and diffusion activation enthalpies which are linear in the stress, in order to account for its dependence on the local stress state and its gradient. Here, more accurate local approximations to the vacancy formation and diffusion activation enthalpies, and the simulation methods needed to implement them, are introduced. The accuracy of both these approximations and the linear approximations are assessed via comparison to full atomistic studies for the problem of vacancies around a Lomer dislocation in Aluminium. Results show that the local and linear approximations for the vacancy formation enthalpy and diffusion activation enthalpy are accurate to within 0.05 eV outside a radius of about 13 Å (local) and 17 Å (linear) from the centre of the dislocation core or, more generally, for a strain gradient of roughly up to 6 × 10^6 m^-1 and 3 × 10^6 m^-1, respectively. These results provide a basis for the development of multiscale models of diffusion under highly non-uniform stress

Structural phase transformations in metallic grain boundaries

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomistic modeling has been rooted in inadequate simulation methodology. The proposed new methodology allows variations in atomic density inside the grain boundary and reveals multiple grain boundary phases with different atomic structures. Reversible first-order transformations between such phases are observed by varying temperature or injecting point defects into the boundary region. Due to the presence of multiple metastable phases, grain boundaries can absorb significant amounts of point defects created inside the material by processes such as irradiation. We propose a novel mechanism of radiation damage healing in metals which may guide further improvements in radiation resistance of metallic materials through grain boundary engineering.Comment: 25 pages, 11 figure

Evaluation of Constant Potential Method in Simulating Electric Double-Layer Capacitors

A major challenge in the molecular simulation of electric double layer capacitors (EDLCs) is the choice of an appropriate model for the electrode. Typically, in such simulations the electrode surface is modeled using a uniform fixed charge on each of the electrode atoms, which ignores the electrode response to local charge fluctuations induced by charge fluctuations in the electrolyte. In this work, we evaluate and compare this Fixed Charge Method (FCM) with the more realistic Constant Potential Method (CPM), [Reed, et al., J. Chem. Phys., 126, 084704 (2007)], in which the electrode charges fluctuate in order to maintain constant electric potential in each electrode. For this comparison, we utilize a simplified LiClO$_4$-acetonitrile/graphite EDLC. At low potential difference ($\Delta\Psi\le 2V$), the two methods yield essentially identical results for ion and solvent density profiles; however, significant differences appear at higher $\Delta\Psi$. At $\Delta\Psi\ge 4V$, the CPM ion density profiles show significant enhancement (over FCM) of "partially electrode solvated" Li$^+$ ions very close to the electrode surface. The ability of the CPM electrode to respond to local charge fluctuations in the electrolyte is seen to significantly lower the energy (and barrier) for the approach of Li$^+$ ions to the electrode surface.Comment: Corrected typo

Method for Computing Short-Range Forces between Solid-Liquid Interfaces Driving Grain Boundary Premelting

We present a molecular dynamics based method for computing accurately short-range structural forces resulting from the overlap of spatially diffuse solid-liquid interfaces at wetted grain boundaries close to the melting point. The method is based on monitoring the fluctuations of the liquid layer width at different temperatures to extract the excess interfacial free-energy as a function of this width. The method is illustrated for a high energy Sigma 9 twist boundary in pure Ni. The short-range repulsion driving premelting is found to be dominant in comparison to long-range dispersion and entropic forces and consistent with previous experimental findings that nanometer-scale layer widths may only be observed very close to the melting point.Comment: 5 pages, four figure

Moabite Stele Translation in Alphabetic Akkadian Shows Early-Jewish / Phoenician Religious Debate Over a Drought (980 BCE)

The Moabite Stele text is a line by line philosophical/religious debate. It was written in Alphabetic Akkadian which was the common trading language of the ancient Mediterranean as evidenced by a growing corpus of texts. The Moabite text is also the earliest archaeological linguistic evidence of Jewish (Judahite) culture yet discovered. This is evidenced by its use of the word “Yahweh,” its description of Ba’al as an opponent, and its developing legalistic framework evidenced by using the word “sin.” Additionally, it supports in a general way the exodus tradition out of Egypt through Moab. The stele’s letter style is a direct descendent of Minoan Linear A in a lineage separate from the Phoenician and Philistine letter styles. This sort of cultural contact could only have occurred earlier in Egypt where the Minoans were trading. The Stele’s Jewish / Phoenician debate foreshadows the conflict between Elijah and Phoenician born Queen Jezebel during the next drought of 840 BCE. Yahu (short form of Yahweh) is mentioned in all its linguistic variants by both sides of the debate as YH, IH, EH, I’, and EA. Yahu is not unique to the Jewish tradition as it is also found in most other Alphabetic Akkadian texts throughout the Mediterranean. Also mentioned in the Moabite Stele are the deities Hu, Su, Ayu, Atu, Ba’al, and Alu

Punic War Text Translations from Carthage in Alphabetic Akkadian (246 to 146 BCE)

Two well preserved Punic texts from Carthage are translated and fully justified according to the scholar’s standard showing that Phoenician letter style texts are actually in the Akkadian empire language just like all other pre-Hellenistic Mediterranean texts. The black temple plaque has a poignant yet sophisticated argument blaming first one divine power then another for Carthage’s problems before ending with a statement blaming all the “high powers.” Despite admitting that their emotion magic is mostly ineffective, this text still implies it is their only hope against their enemy mentioned in Line 2. This “enemy” follows the sun/storm god “Atu” which can only be Rome. The temple plaque mentions these deities: Su (full moon god, father time), Atu (sun/storm god), Hu (healing sun god), the Revealer (Yahu), the Reed-Boat (goddess Ayu), and the Opener (goddess Utu). The second text is on a white gravestone from Carthage’s child cemetery (Tophet) and it is blaming some local drought on the lack of activity in the magical motion powers. Deities mentioned in the gravestone are the Revealer (Yahu) and Reed-Boat (crescent moon goddess Ayu). Neither text mentions Tanit, the supposed goddess of the Phoenicians, or child sacrifice

Nora Stone from Sardinia Translated in Alphabetic Akkadian Gives Statement about Purpose of Phoenician Temples (730 BCE)

The text on this large stone stele is a defense of Phoenician temple activity. Consequently, it was likely placed outside the main temple in the Phoenician trading port of Nora on the southern coast of Sardinia. Its theme is also Phoenician in that it is promoting emotion magic to overcome a drought. This drought is most likely the drought of 730 BCE which lead to the Assyrian invasion of the Levant. Finally, its letter style is mostly Phoenician with only a few late Philistine/early Etruscan style letters thrown in. Consequently, this text similar to the Phoenician gold Pyrgi foil (Olmsted November 28, 2020). Like the Pyrgi foil, the underlying language is the empire language of Akkadian used for trade, temple, and government throughout Mesopotamia and the Mediterranean. Deities mentioned are the god Yahu (Yahweh) and the Reed-Boat as an epithet for the goddess Ayu. This Alphabetic Akkadian text is compared and contrasted with the earlier proposed Hebrew translations

Translations Texts at Egyptian Wadi el-Hol (1550 BCE) in Akkadian

The inscriptions at Wadi el-Hol just north of Memphis, Egypt are a late variant of Minoan Linear A showing its progression towards alphabetic writing with its treatment of phoneme signs more as wildcard signs able to be followed by any vowel sound. The Minoans were in Egypt during the early 18th dynasty as revealed by Minoan artwork discovered at Tell el-Dab’a (former Hyksos capital of Avaris). Full alphabetic writing would start appearing 100 years later at the Egyptian turquoise mine at Serabit el-Khadim. The vertical inscription is mostly pictographic illustrating an attack on a marching camp while the horizontal inscription is a text which describes the reasons for the attack as hunger among some tribes