Sliding friction of graphene/hexagonal -boron nitride heterojunctions: a route to robust superlubricity.

The origin of ultra-low friction exhibited by heterogeneous junctions of graphene and hexagonal boron nitride (h-BN) is revealed. For aligned interfaces, we identify a characteristic contact size, below which the junction behaves like its homogeneous counterparts with friction forces that grow linearly with the contact area. Superlubricity sets in due to the progressive appearance of Moiré patterns resulting in a collective stick-slip motion of the elevated super-structure ridges that turns into smooth soliton-like gliding with increasing contact size. Incommensurability effects are enhanced in misaligned contacts, where the friction coefficients further drop by orders of magnitude. Our fully atomistic simulations show that the superlubric regime in graphene/h-BN heterostructures persists up to significantly higher loads compared to the well-studied twisted homogeneous graphene interface. This indicates the potential of achieving robust superlubricity in practical applications using two-dimensional layered materials heterojunctions.

[Neurologic manifestations of HIV infection].

The sole universally recognized diagnostic criterion for the affection of central nervous system by immunodeficiency virus is AIDS-dementia complex. Its main pathognomonic feature is progressive intellect failure although most patients do not experience intellect deficit. Instead, they present with other disorders in the central nervous system. This article focuses on their early diagnosis.

[The sociological monitoring as a tool to evaluate preventive activities].

The monitoring of conditions of HIV-infection spreading includes qualitative research methods to reveal specified information from people relating immediately to the problem of HIV-infection prevalence. The acquired information can be used both for monitoring of the conditions of HIV-infection spreading (morbidity, prevalence, mortality) and adjustment of preventive activities at the level of specific administrative territory.

[Use of transcutaneous electroneurostimulation for enhancing the effectiveness of conduction anesthesia in dental polyclinic practice]. / Primenenie chreskozhnoi élektroneirostimuliatsiia dlia povysheniia éffektivnosti provodnikovogo obezbolivaniia v poliklinicheskoi stomatologicheskoi praktike.

The efficiency of mandibular conduction anesthesia was assessed in patients with inflammatory disorders in the area innervated by the mandibular nerve. In patients with conduction anesthesia induced after an electroneurostimulation session, the efficiency of anesthesia was considerably higher than in those operated on under mandibular anesthesia only.