Nondestructive preparation of bicontinuous nanoporous metal membranes by replication of bicontinuous nanoporous polymeric membranes consisting of recoverable asymmetric block copolymers (BCPs) is reported. The BCP membranes are generated by swelling the minority domains of the BCP with selective solvents accompanied by reconstruction of the glassy matrix formed by the majority component (see figure).

Conventional proton exchange membrane fuel cells (PEMFCs) operate at a narrow temperature range, either under low temperature conditions (80-90°C) using fully-humidi ed per uorosulfonic acid (Na on®) membranes or under nonhumidi ed high temperature conditions (140-180°C) using phosphoric acid (PA)-doped membranes to avoid water condensation-induced PA leaching. To allow wide operational exibility over the full spectrum of temperature and humidity ranges, we present an innovative design strategy by using PA-doped intrinsically ultramicroporous membranes constructed from rigid and contorted high free volume polymers. The membranes with an average ultramicropore radius of 3.3 Å showed a signi cant siphoning effect as con rmed by the delocalization of PA in 31 P NMR, thus allowing high retention of PA even under highly humidi ed conditions and presenting more than three orders of magnitude higher proton conductivity retention than conventional dense PA-doped polybenzimidazole membranes (PBI/PA). The resulting PEMFCs display impressive performance over a much broader temperature range from − 20 to 200°C and can accomplish over 100 startup/shut-down cycles even at − 20°C. The broad operational exibility rendered from the high PA-retention can ultimately simplify heat and water management and thereby reduce PEMFC costs.

The past few decades have witnessed growing research interest in developing powerful nanofabrication technologies for three-dimensional (3D) structures and devices to achieve nano-scale and nano-precision manufacturing.

A bulk dielectric polymer film with an intrinsic ultralow k value of 1.52 at 10 kHz has been successfully synthesized based on a novel polyimide FPTTPI. More importantly, such outstanding dielectric properties remain stable up to 280°C. The excellent ultralow dielectric properties are mainly because of the larger free volume (subnanoscale), which intrinsically exists in the amorphous region of polymeric materials. Meanwhile, FPTTPI also shows excellent thermal stability and mechanical properties, with a glass-transition temperature (T g ) of 280°C, 5 wt % loss temperature of 530°C, and a residual of 63% at 800°C under N 2 . It was soluble in common solvents, which made it possible to undergo simple spin-on or efficient, low-cost, and continuous roll-to-roll processes. ■ INTRODUCTIONWith the development of ultralarge-scale integration (ULSI) to high speed and high integration in the semiconductor industry, and with the continuing miniaturization in the dimensions of electronic devices utilized in ULSI circuits, an urgent need exists for high-performance low-k and ultralow-k dielectric materials (low-k: k ≤ 2.5; ultralow-k: k ≤ 2.0) has arisen. 1−4 Such dielectrics materials would reduce the capacitance between the metal interconnects, the resistance-capacitance delay, the line-to-line crosstalk noise, and the power dissipation; 5−7 these materials also have important application prospects in the fields of interlayer dielectric, semiconductor packaging (chips modules, etc.), and high-frequency, low-loss boards etc. So far, research of low-dielectric materials as an alternative to the workhorse dielectrics silicon dioxide (k = 3.9−4.3) are continually being pursued today, which mainly including organosilicates and organic polymers. 8−13 Compared with inorganic dielectric materials, organic polymer materials often have a lower dielectric constant, because of the lower materials density and lower individual bond polarizability. Moreover, they show distinct advantages, in terms of easy chemical and geometric structural design. 14−18 Thus, they have attracted much interest. Generally, by decreasing the dipole strength or the number of dipoles or a combination of both, the dielectric constant of full dense polymer materials can be lowered to 2.2−2.6. 5,19−22 The most common way is fluorination of dielectric materials or increasing the free volume by rearranging the material structure. 23−27 However, it seems that no true dielectric generational extendibility to the ultralow-k region can be achieved without embracing the concept of porosity, either for organosilicates or organic polymers. 28−32 The k-value of these porous materials can be less than 1.5, 33−39 but the method itself is complicated, difficult to control, and expensive. Moreover, the pore structure, the size, and the distribution would greatly affect the homogeneity of the materials, which makes this technique difficult for large-area applications. In addition, the porosity tends to dramatically reduce the mechanical strength and increase the permeability o...

Developing highly efficient photocatalysts to utilize solar radiation for converting CO2 into solar fuels is of great importance for energy sustainability and carbon neutralization. Herein, through an alkali-etching-introduced interface reconstruction strategy, a nanowire photocatalyst denoted as V–Bi19Br3S27, with rich Br and S dual-vacancies and surface Bi–O bonding introduced significant near-infrared (NIR) light response, has been developed. The as-obtained V–Bi19Br3S27 nanowires exhibit a highly efficient metallic photocatalytic reduction property for converting CO2 into CH3OH when excited solely under NIR light irradiation. Free of any cocatalyst and sacrificial agent, metallic defective V–Bi19Br3S27 shows 2.3-fold higher CH3OH generation than Bi19Br3S27 nanowires. The detailed interfacial structure evolution and reaction mechanism have been carefully illustrated down to the atomic scale. This work provides a unique interfacial engineering strategy for developing high-performance sulfur-based NIR photocatalysts for photon reducing CO2 into alcohol for achieving high-value solar fuel chemicals, which paves the way for efficiently using the solar radiation energy extending to the NIR range to achieve the carbon neutralization goal.

Endometrial cancer (EC) is the most frequent gynecological malignancy and a major cause of morbidity and mortality for women worldwide. Programmed cell death protein 1 (PD-1) and its ligands programmed death ligand 1 (PD-L1) and programmed death ligand 2 (PD-L2) have been well studied in lung cancer, melanoma and renal-cell cancer. However, few studies have been performed in EC. The purpose of the present study was to assess the expression of PD-1, PD-L1 and PD-L2 in 35 human normal endometrial tissue samples and 75 human EC tissue samples using immunohistochemical staining. It was found that 61.3% of ECs were positive for PD-1 staining, which was almost exclusively found in the tumor-infiltrating immune cells. By contrast, PD-1 was not expressed in the tumor cells or normal endometrial tissues. It was also found that 14.3% of normal endometria and 17.3% of EC tissues were positive for PD-L1 expression, while 20.0% of normal endometrium and 37.3% of EC tissues were positive for PD-L2 expression; however, there was no statistically significant difference between the normal endometrium and EC tissues. PD-1 expression in the tumor-infiltrating immune cells was more frequently found in the moderately and poorly-differentiated ECs and non-endometrioid (type II) ECs than in the well-differentiated ECs and endometrioid (type I) ECs. Similarly, PD-L1 and PD-L2 expression in the tumor-infiltrating immune cells was more frequently found in the moderately and poorly-differentiated ECs and type II ECs than in the type I ECs. The present findings indicate a possible better outcome for future treatment with anti-PD-1 or anti-PD-L1 antibody-based therapies against these subgroups of endometrial cancers with frequent expression of the PD-1/PD-L1/PD-L2 axis.

We reported the deliberate control on the micelle opening and closing of amphiphilic polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) micellar films by exposing them to selective solvents. We first treated the micellar films with polar solvents including ethanol and water (pH = 4, 8, and 12) that have different affinities to P2VP. We observed opening of the micelles in all the cases. Both the size of opened pores and the opening rate are dependent on the solvency of different solvents for P2VP. We then explored the closing behavior of the opened micelles using solvents having different affinities to PS. We found that the opened micelles were recovered to their initial closed micelle forms. The recovery was accompanied by a slow micelle disassociation process which gradually reduced the micelle size. The rates of the micelle closing and disassociation are also dependent on the solvency of different solvents for PS.

A bio-sourced, low-toxic monomer was facilely synthesized and used to build controlled degradable, strong and tough thermosetting plastics.