It is concluded that the force needed for the displacement of the nano-modification of WMTA (NWMTA) was significantly higher than for Angelus WMTA and Bioaggregate.

Air abrasion has a greater effect than CO₂and Er,Cr:YSGG lasers in the treatment of zirconia ceramic surfaces to enhance the bonding strength of resin cement to zirconia. CO₂laser at 4W and Er,Cr:YSGG laser at only 3-W output power can be regarded as surface treatment options for roughening the zirconia surface to establish better bond strength with resin cements.

Biological ion channels feature angstrom‐scale asymmetrical cavity structures, which are the key to achieving highly efficient separation and sensing of alkali metal ions from aqueous resources. The clean energy future and lithium‐based energy storage systems heavily rely on highly efficient ionic separations. However, artificial recreation of such a sophisticated biostructure has been technically challenging. Here, a highly tunable design concept is introduced to fabricate monovalent ion‐selective membranes with asymmetric sub‐nanometer pores in which energy barriers are implanted. The energy barriers act against ionic movements, which hold the target ion while facilitating the transport of competing ions. The membrane consists of bilayer metal‐organic frameworks (MOF‐on‐MOF), possessing a 6 to 3.4‐angstrom passable cavity structure. The ionic current measurements exhibit an unprecedented ionic current rectification ratio of above 100 with exceptionally high selectivity ratios of 84 and 80 for K+/Li+ and Na+/ Li+, respectively (1.14 Li+ mol m−2 h−1). Furthermore, using quantum mechanics/molecular mechanics, it is shown that the combined effect of spatial hindrance and nucleophilic entrapment to induce energy surge baffles is responsible for the membrane's ultrahigh selectivity and ion rectification. This work demonstrates a striking advance in developing monovalent ion‐selective channels and has implications in sensing, energy storage, and separation technologies.

This paper considers the problem of information-theoretic Secret Key Establishment (SKE) in the presence of a passive adversary, Eve, when Alice and Bob are connected by a pair of independent discrete memoryless broadcast channels in opposite directions. We refer to this setup as 2DMBC. We define the secret-key capacity in the 2DMBC setup and prove lower and upper bounds on this capacity. The lower bound is achieved by a two-round SKE protocol that uses a two-level coding construction. We show that the lower and the upper bounds coincide in the case of degraded DMBCs. 3 communication is eavesdropped by neighbors in their communication range. The 2DMBC setup gives the promise of interactive communication, while the only resources provided to the parties are DMBCs.We define SKE in the 2DMBC setup as a multi-round protocol between Alice and Bob with the aim of establishing a secure and reliable key. In analogy to the secrecy capacity [6], [15], [23], we define the secret-key capacity in this setup, denoted by C 2DM BC sk , as the maximum achievable secret-key rate, in bits per use of the channel. We have the following results.1) Lower bound: We give a lower bound on the secret-key capacity. We propose a two-round SKE protocol that uses a two-level channel coding construction, and prove that it achieves the lower bound. Our lower bound can also be derived by using the SKE protocols in the DMMS-and-DMBC setup [10], [19]. However, while the SKE protocols proposed in [10], [19] are combinations of different constructions for different cases (depending on the setup's specification), our proposed SKE protocol uses a concrete construction that achieves the lower bound for all cases.2) Upper bound: We prove an upper bound on the secret-key capacity. This bound holds for all the secret-key rates achievable by SKE protocols with no limitation on the number of communication rounds.3) Degraded 2DMBCs: We study the 2DMBC setup when the broadcast channels are degraded. We show that in this setup the lower and the upper bounds coincide, and the secret-key capacity can be achieved by a one round SKE protocol. This implies that, in the case of degraded 2DMBCs, interactive communication cannot improve the secret-key rate and the optimal solution is key transport, i.e., one party choosing a key and sending it securely though the (one-way) DMBC, i.e., following the the work in [6]. B. Discussion 1) Types of key establishment protocols:We observe that SKE in the 2DMBC setup can take one of the following forms:

No abstract

For a finite group G different from a cyclic group of prime power order, we introduce an undirected simple graph D(G) whose vertices are the proper subgroups of G which are not contained in the Frattini subgroup of G and two vertices H and K are joined by an edge if and only if G hHY Ki. In this paper we study D(G) and show that it is connected and determine the clique and chromatic number of D(G) and obtain bounds for its diameter and girth. We classify finite groups with complete graphs and also classify finite groups with domination number 1. Also we show that if the independence number of the graph D(G) is at most 7, then G is solvable.

Lithium consumption is estimated to face a considerable rise in the next decade; thus, finding new reproducible lithium resources such as brine deposits and seawater has become a fast‐growing research topic. However, Li+ extraction from these resources is challenging due to its low concentration and presence of other monovalent cations exhibiting identical chemical properties. Here, it is discovered that tannic acid (TA) inside graphene oxide (GO) nanochannel acts as natural ion trapper, which possesses lithiophilic elements. The lithium‐rich feed is achieved by using the potential‐driven TA‐GO membrane by excluding lithium ions from other monovalent cations. The results showed that the ion trapping capability of inexpensive TA‐GO membrane is Li+ > Na+ > K+ with Li trapping energy of −593 KJ mol−1, respectively, where its trapping efficiency goes into a top rank among their expensive synthetic counterparts. Evaluating the combined effect of three key parameters, including barrier energy, hydration energy, and binding energy illustrates that required energy to transport Li‐ion through the membrane is higher than that for other monovalent. This proof‐of‐concept work opens up an avenue of research for designing a new class of ion‐selective membranes, based on the incorporation of naturally low cost available lithiophilic guest molecules into 2D membranes.

No abstract