Layering in the Ising model

We consider the three-dimensional Ising model in a half-space with a boundary field (no bulk field). We compute the low-temperature expansion of layering transition lines

A lattice model for the line tension of a sessile drop

Within a semi--infinite thre--dimensional lattice gas model describing the coexistence of two phases on a substrate, we study, by cluster expansion techniques, the free energy (line tension) associated with the contact line between the two phases and the substrate. We show that this line tension, is given at low temperature by a convergent series whose leading term is negative, and equals 0 at zero temperature

Theoretical Characterization of the Interface in a Nonequilibrium Lattice System

The influence of nonequilibrium bulk conditions on the properties of the interfaces exhibited by a kinetic Ising--like model system with nonequilibrium steady states is studied. The system is maintained out of equilibrium by perturbing the familiar spin--flip dynamics at temperature T with completely--random flips; one may interpret these as ideally simulating some (dynamic) impurities. We find evidence that, in the present case, the nonequilibrium mechanism adds to the basic thermal one resulting on a renormalization of microscopic parameters such as the probability of interfacial broken bonds. On this assumption, we develop theory for the nonequilibrium "surface tension", which happens to show a non--monotonous behavior with a maximum at some finite T. It ensues, in full agreement with Monte Carlo simulations, that interface fluctuations differ qualitatively from the equilibrium case, e.g., the interface remains rough at zero--T. We discuss on some consequences of these facts for nucleation theory, and make some explicit predictions concerning the nonequilibrium droplet structure.Comment: 10 pages, 7 figures, submitted to Phys. Re

Djelovanje per- i polifluoroalkilnih tvari na okolišne i ljudske mikroorganizme i njihov potencijal za bioremedijaciju

Utilised in a variety of consumer products, per- and polyfluoroalkyl substances (PFAS) are major environmental contaminants that accumulate in living organisms due to their highly hydrophobic, lipophobic, heat-resistant, and non-biodegradable properties. This review summarizes their effects on microbial populations in soils, aquatic and biogeochemical systems, and the human microbiome. Specific microbes are insensitive to and even thrive with PFAS contamination, such as Escherichia coli and the Proteobacteria in soil and aquatic environments, while some bacterial species, such as Actinobacteria and Chloroflexi, are sensitive and drop in population. Some bacterial species, in turn, have shown success in PFAS bioremediation, such as Acidimicrobium sp. and Pseudomonas parafulva.Budući da se koriste u izradi raznih potrošačkih proizvoda, per- i polifluoroalkilne tvari (engl. per- and polyfluoroalkyl substances, krat. PFAS) veliki su zagađivači okoliša koji se nakupljaju u živim organizmima zbog svoje izrazite hidrofobičnosti, lipofobičnosti, otpornosti na topline i biološke nerazgradljivosti. Ovaj članak donosi sažeti pregled njihova djelovanja na populacije mikroba u tlu, vodnim i biogeokemijskim sustavima te na humanom mikrobiomu. Pojedini su mikrobi neosjetljivi na zagađenje PFAS-om, čak i napreduju, poput bakterije Escherichia coli i proteobakterija u tlu i vodi, a osjetljive su pojedine bakterijske vrste, poput rodova Actinobacteria i Chloroflexi, pa im se smanjuje populacija u takvom okružju. Neke su se, pak, bakterije pokazale uspješnima u bioremedijaciji, poput vrsta Acidimicrobium sp. i Pseudomonas parafulva

Pemberian Motivasi Berwirausaha Online Kepada Siswa-siswi SMA Perguruan Advent Bogor

Toko online adalah suatu tempat kita bisa menjual, memajang, dan memperlihatkan barang dagangan diinternet. Konsep Toko online ini memungkinkan kita selaku konsumen membeli barang sesuai dengankebutuhan tanpa perlu datang ke tempat penjualnya langsung, disamping itu para pelajar diharuskan untuk dapatmengikuti perkembangan zaman dimana segala sesuatu yang rumit sudah berubah menjadi instan. Tokopediamerupakan salah satu bentuk toko online yang berhasil menarik banyak penjual dan pembeli untuk bertransaksiTujuan dari pelatihan ini adalah untuk memotivasi para pelajar untuk memahami peluang berjualan online danmampu mengimplementasikan dalam dunia nyata. Metode dilakukan dengan ceramah terhadap peserta di kelasatau ruangan tertentu dan menyampaikan materi serta tindakan nyata yang telah dilaksanakan sebelumnya dalamdunia/bisnis toko online

Systematic first-principles study of impurity hybridization in NiAl

We have performed a systematic first-principles computational study of the effects of impurity atoms (boron, carbon, nitrogen, oxygen, silicon, phosporus, and sulfur) on the orbital hybridization and bonding properties in the intermetallic alloy NiAl using a full-potential linear muffin-tin orbital method. The matrix elements in momentum space were used to calculate real-space properties: onsite parameters, partial densities of states, and local charges. In impurity atoms that are empirically known to be embrittler (N and O) we found that the 2s orbital is bound to the impurity and therefore does not participate in the covalent bonding. In contrast, the corresponding 2s orbital is found to be delocalized in the cohesion enhancers (B and C). Each of these impurity atoms is found to acquire a net negative local charge in NiAl irrespective of whether they sit in the Ni or Al site. The embrittler therefore reduces the total number of electrons available for covalent bonding by removing some of the electrons from the neighboring Ni or Al atoms and localizing them at the impurity site. We show that these correlations also hold for silicon, phosporus, and sulfur.Comment: Revtex, 8 pages, 7 eps figures, to appear in Phys. Rev.

Controlling crystallization and its absence: Proteins, colloids and patchy models

The ability to control the crystallization behaviour (including its absence) of particles, be they biomolecules such as globular proteins, inorganic colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and technological importance. Much can be learnt from the exquisite control that biological systems exert over the behaviour of proteins, where protein crystallization and aggregation are generally suppressed, but where in particular instances complex crystalline assemblies can be formed that have a functional purpose. We also explore the insights that can be obtained from computational modelling, focussing on the subtle interplay between the interparticle interactions, the preferred local order and the resulting crystallization kinetics. In particular, we highlight the role played by ``frustration'', where there is an incompatibility between the preferred local order and the global crystalline order, using examples from atomic glass formers and model anisotropic particles.Comment: 11 pages, 7 figure