Nanonetwork-structured materials can be found in nature and synthetic materials. A double gyroid (DG) with a pair of chiral networks but opposite chirality can be formed from the self-assembly of diblock copolymers. For triblock terpolymers, an alternating gyroid (GA) with two chiral networks from distinct end blocks can be formed; however, the network chirality could be positive or negative arbitrarily, giving an achiral phase. Here, by taking advantage of chirality transfer at different length scales, GA with controlled chirality can be achieved through the self-assembly of a chiral triblock terpolymer. With the homochiral evolution from monomer to multichain domain morphology through self-assembly, the triblock terpolymer composed of a chiral end block with a single-handed helical polymer chain gives the chiral network from the chiral end block having a particular handed network. Our real-space analyses reveal the preferred chiral sense of the network in the GA, leading to a chiral phase.

We explore the generality of the influence of segment chirality on the self-assembled structure of achiral–chiral diblock copolymers. Poly(cyclohexylglycolide) (PCG)-based chiral block copolymers (BCPs*), poly(benzyl methacrylate)-b-poly(d-cyclohexylglycolide) (PBnMA-PDCG) and PBnMA-b-poly(l-cyclohexyl glycolide) (PBnMA-PLCG), were synthesized for purposes of systematic comparison with polylactide (PLA)-based BCPs*, previously shown to exhibit chirality transfer from monomeric unit to the multichain domain morphology. Opposite-handed PCG helical chains in the enantiomeric BCPs* were identified by the vibrational circular dichroism (VCD) studies revealing transfer from chiral monomers to chiral intrachain conformation. We report further VCD evidence of chiral interchain interactions, consistent with some amounts of handed skew configurations of PCG segments in a melt state packing. Finally, we show by electron tomography [3D transmission electron microscope tomography (3D TEM)] that chirality at the monomeric and intrachain level ultimately manifests in the symmetry of microphase-separated, multichain morphologies: a helical phase (H*) of hexagonally, ordered, helically shaped tubular domains whose handedness agrees with the respective monomeric chirality. Critically, unlike previous PLA-based BCP*s, the lack of a competing crystalline state of the chiral PCGs allowed determination that H* is an equilibrium phase of chiral PBnMA-PCG. We compared different measures of chirality at the monomer scale for PLA and PCG, and argued, on the basis of comparison with mean-field theory results for chiral diblock copolymer melts, that the enhanced thermodynamic stability of the mesochiral H* morphology may be attributed to the relatively stronger chiral intersegment forces, ultimately tracing from the effects of a bulkier chiral side group on its main chain.

Herein, enantiomeric polylactide-containing chiral block copolymers (BCPs*) with aliphatic and aromatic junctions are designed and synthesized for investigating the impact of junction π–π interactions on the self-assembly of BCPs*. A profound effect on the microphase separation of the BCP* can be found by introducing the π–π interaction of junctions, resulting in reduced structural ordering due to the mixing of constituted blocks by the formation of junction π-stacking. An ordered microphase-separated structure of the BCP* can be obtained by decreasing the number of aromatic rings of the junction or increasing the total molecular weight of the BCP*. Accordingly, competitive interactions of π–π junctions and microphase separation of the BCP* can be manifested by tuning the thermodynamic driving force for self-organization through molecular design. Most interestingly, the self-assembled morphology can be amended by self-assembling the BCP* from solution through the kinetic control of solvent evaporation. Fast solvent evaporation limits the formation of junction stacking while slow solvent evaporation enhances the π–π stacking between junctions, and thus depresses the microphase separation of BCPs*. The self-assembled mechanisms are further evidenced by spectroscopic results and the corresponding induced circular dichroism (ICD) behaviors of the aromatic junctions. This work demonstrates a new approach to thermodynamically and kinetically regulate the self-assembled morphologies of BCP* by introducing the competitive interactions of π–π junctions on self-assembly.

Temporomandibular joint disorder (TMD) refers to persistent medical conditions that affect the temporomandibular joint (TMJ) and related structures. Studies showed that stress was closely linked to the development of TMD. Furthermore, healthcare students are particularly susceptible to stress compared to the general population. This can have a negative impact on their quality of life and mental health during their training. The increased prevalence of TMD has also been reported among the same cohort of the population. However, there is a lack of literature published highlighting the prevalence of TMD and their association with increased levels of stress in dental students. This study aims to explore whether increased stress levels are associated with the prevalence of TMD in undergraduate dental students. A total of 218 dental students participated. Two online self-reported questionnaires consisted of structured case history on past medical and dental history with a Fonseca Amnestic Index (FAI) questionnaire used to identify the prevalence of TMD and DESS questionnaire for stress prediction were used. Data were analyzed using SPSS version 22 with a p-value less than 0.05. It was reported that about 48% of students had various TMD with no significant association found between the year of study and gender. However, a significant association was reported between stress gender. A positive correlation was also found between stress and TMD among participants. This study revealed a significant association between stress and the prevalence of TMD in undergraduate dental students. Educational institutions must adopt coping strategies to help trainees manage their psychological stress, which could reduce the incidence of TMD.

Oligonucleotides were inserted into the Lp3 region of a hepatitis delta virus (HDV) cis-cleaving ribozyme and the effect of Lp3 enlargement on ribozyme folding was examined by assaying the activity of each mutant. The location of insertion and the sequence of the inserted oligonucleotide had distinct effects on ribozyme activity, and the HDV ribozyme was capable of adopting the active structure for cis-cleavage when a pentanucleotide was inserted into the 3P portion of Lp3. Furthermore, whether the insertion mutant cis-cleaved or not, the structure of Lp3 was altered by the inserted oligonucleotide. These findings disclose that the 5P rather than the 3P portion of Lp3 is critical for ribozyme folding and catalysis.z 1998 Federation of European Biochemical Societies.