Self‐Degradable Lipid‐Like Materials Based on “Hydrolysis accelerated by the intra‐Particle Enrichment of Reactant (HyPER)” for Messenger RNA Delivery

RNA‐based therapeutics is a promising approach for curing intractable diseases by manipulating various cellular functions. For eliciting RNA (i.e., mRNA and siRNA) functions successfully, the RNA in the extracellular space must be protected and it must be delivered to the cytoplasm. In this study, the development of a self‐degradable lipid‐like material that functions to accelerate the collapse of lipid nanoparticles (LNPs) and the release of RNA into cytoplasm is reported. The self‐degradability is based on a unique reaction “Hydrolysis accelerated by intra‐Particle Enrichment of Reactant (HyPER).” In this reaction, a disulfide bond and a phenyl ester are essential structural components: concentrated hydrophobic thiols that are produced by the cleavage of the disulfide bonds in the LNPs drive an intraparticle nucleophilic attack to the phenyl ester linker, which results in further degradation. An oleic acid‐scaffold lipid‐like material that mounts all of these units (ssPalmO‐Phe) shows superior transfection efficiency to nondegradable or conventional materials. The insertion of the aromatic ring is unexpectedly revealed to contribute to the enhancement of endosomal escape. Since the intracellular trafficking is a sequential process that includes cellular uptake, endosomal escape, the release of mRNA, and translation, the improvement in each process synergistically enhances the gene expression.     

无铬无脂猪革的性能

制革废水及革制品废料所含铬引起的环境与卫生污染是一个严重的问题。加脂可以影响皮革的性能，其目的就是赋予成革以柔软性，良好的手感和一定的强度，缺点是加脂使革重量增加，抗水性减弱，有时还会引起增塑剂和染料的迁移。为解决此问题，本论文采用不使用铬和加脂剂的方法来处理皮革，并对以这种方法所加工皮革的性能进行研究。结果如下：（１）对于剖层，削匀或修边等废料，因其不含铬而可加以利用或焚烧处理；（２）所制成革具有防水性，性能优于防水性的革；（３）成革视密度下降；（４）染色革的耐光性明显优于荆树皮～铝鞣革，后者系典型的非铬鞣革之一，此法还可有效防止白色革泛黄。     

Thermoelectric Properties of a 593-nm Individual Bismuth Nanowire Prepared Using a Quartz Template

An individual bismuth nanowire sample, 593 nm in diameter and 1.64 mm in length, has been successfully grown using a quartz template. The resistivity and the Seebeck coefficient of the nanowire at 300 K were 1.35 μΩ m and −59 μV/K, respectively, similar to those of a bismuth bulk sample. The temperature dependence of the resistivity was found to decrease with temperature from 300 K to 175 K and then increase with further temperature reduction below 175 K. The absolute value of the Seebeck coefficient decreased with temperature from 300 K to 90 K, and the sign of the Seebeck coefficient changed from negative to positive near 90 K. This result indicated that there was a small amount of contamination in the bismuth. The carrier density was estimated from the resistivity and Seebeck coefficient on the basis of limitation of the mean free path and a two-carrier model, and the observed temperature dependences are discussed.     

A Pulsewidth Controlled AC-to-DC Converter to Improve Power Factor and Waveform of AC Line Current

As a method for improving power factor and waveform of ac line current drawn by an ac-to-dc converter a new pulsewidth controlled converter is proposed, its commutation mechanism is described, and experimental results are given which show a good power factor, a good waveform of the line current, and a wide adjustable range of dc output voltage.     

Domain-Swapping Design by Polyproline Rod Insertion

During domain swapping, proteins mutually interconvert structural elements to form a di-/oligomer. Engineering this process by design is important for creating a higher order protein assembly with minimal modification. Herein, a simple design strategy is shown for domain-swapping formation by loop deletion and insertion of a polyproline rod. Crystal structures revealed the formation of the domain-swapped dimers and polyproline portion formed a polyproline II (PPII) structure. Small-angle X-ray scattering demonstrated that an extended orientation of domain-swapped dimer was retained in solution. It is found that a multiple of three of inserting proline residue is favored for domain swapping because of the helical nature of PPII. The rigid nature of the polyproline rod enables precise control of the interdomain distance and orientation.     

New Method for Reducing Harmonics Involved in Input and Output of Rectifier with Interphase Transformer

A new effective method for reducing harmonics involved in input ac line currents or output dc voltage of the thyristor rectifier apparatus with an interphase transformer is proposed. This method is based on the sophisticated utilization of several thyristors inserted in parallel between several taps equipped symmetrically for the midpoint of the interphase transformer and the terminal of the dc output circuit. The key point of this method can be understood easily when compared with conventional use of the interphase transformer, where the dc output circuit is taken from the midpoint of the interphase transformer directly. The features of this method are very simple and very economical in circuit construction. Their presentation will take the following form: 1) fundamental theory of the method; 2) analysis of waveforms of input ac line currents under optimum operation; 3) checking the validity of the theory by experiment using the six-phase 12-pulse thyristor polyphase rectifier apparatus; 4) various modifications of this method.     

Thermal and gas permeation properties of copolymers derived from 3‐methacryloxypropyltris(trimethylsiloxy)silane and adamantyl group‐containing methacrylate derivatives

Novel copolymer membranes derived from three types of adamantyl group‐containing methacrylate derivatives and 3‐methacryloxypropyltris(trimethylsiloxy)silane (SiMA) were synthesized via free radical polymerization. The thermal and permeation properties of these copolymer membranes were investigated. Copolymer membranes with less than 11.9 mol % adamantane content exhibited good membrane forming abilities that are suitable for permeation measurement. The decomposition temperature of all copolymers increased up to approximately 40–80°C with increasing adamantane content compared with poly(SiMA). Moreover, the glass transition temperature (T_g) of all copolymers increased up to approximately 46–60°C with increasing adamantane content compared with the theoretical value, which was estimated from Fox equation. 1‐Adamantyl methacrylate copolymer had the highest fractional free volume among the three types of adamantly group‐containing methacrylate derivatives. The gas permeability coefficient of this copolymer increased by 22–45% with increasing adamantane content compared with that of poly(SiMA). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43129.     

Preparation of physical gel consisting of syndiotactic polystyrene and poly(ethylene glycol)

Syndiotactic polystyrene (s-PS) was blended with poly(ethylene glycol) (PEG) in 1,2-dichloroethane (DCE) solvent. The mixture became a homogeneous solution at 155 °C depending on the composition ratio of PEG to DCE. When the solution was cooled at the rate of 5 °C/min to room temperature, a thermoreversible gelation was occurred. Wide angle X-ray diffraction (WAXD) measurements revealed that the polymer chain of s-PS in the obtained gel was crystallized with a helical conformation, while that in the non-gelated sample was done with an all-trans planar zigzag conformation.After drying gelated samples at 70 °C for 24 h, a novel polymer blend type of the physical gel consisting of s-PS and PEG was obtained. Dynamic mechanical analysis (DMA) revealed that the physical gel had a high modulus and a long elastic plateau in the temperature range of −80-270 °C.     

Effect of silicate incorporation on in vivo responses of α-tricalcium phosphate ceramics

In addition to calcium phosphate-based ceramics, glass-based materials have been utilized as bone substitutes, and silicate in these materials has been suggested to contribute to their ability to stimulate bone repair. In this study, a silicate-containing α-tricalcium phosphate (α-TCP) ceramic was prepared using a wet chemical process. Porous granules composed of silicate-containing α-TCP, for which the starting composition had a molar ratio of 0.05 for Si/(P + Si), and silicate-free α-TCP were prepared and evaluated in vivo. When implanted into bone defects that were created in rat femurs, α-TCP ceramics either with or without silicate were biodegraded, generating a hybrid tissue composed of residual ceramic granules and newly formed bone, which had a tissue architecture similar to physiological trabecular structures, and aided regeneration of the bone defects. Supplementation with silicate significantly promoted osteogenesis and delayed biodegradation of α-TCP. These results suggest that silicate-containing α-TCP is advantageous for initial skeletal fixation and wound regeneration in bone repair.     

Synthesis of fluoride-releasing carbonate apatites for bone substitutes

Fluoride (F⁻)-substituted B-type carbonate hydroxyapatite (CHAP) powders were prepared for application as bone substitute materials having the ability to enhance bone formation and to suppress bone resorption due to the therapeutic effect of F⁻. F⁻ was adsorbed on CHAP in a sodium fluoride solution followed by heating at 700°C in carbon dioxide flow to substitute F⁻ for the hydroxyl ion in the CHAP structure. The F⁻ contents in the F-substituted CHAP powders were 16–22 times greater than that in normal adult human bones. The carbonate ion contents in the F-substituted CHAP powders corresponded to or were higher than that in normal adult human bones. F-substituted CHAP powder with CO₃²⁻ and F⁻ contents of 11.03 and 0.66 wt%, respectively, slowly released F⁻ in a physiological salt solution to a sufficiently high F⁻ level. The F⁻ concentration slowly increased and reached 67.20 ± 4.81 μg l⁻¹, which was 1.5–9.3 times higher than that in the body fluid of normal adult humans, near the therapeutic window of F⁻, and far lower than the estimated toxic level. Therefore, the F-substituted CHAP can promote bone formation. The present F-substituted CHAP has the advantage of slow F⁻ release over sodium fluoride and sodium monofluorophosphate which are highly soluble salts and cannot be sintered into a ceramic body.