Analysis of therapeutic effectiveness attained through generation of three alpha particles in proton-boron fusion reaction based on Monte Carlo simulation code

This study analyzed the effectiveness attained through generation of three alpha particles in proton-boron fusion therapy (PBFT) based on a Monte Carlo simulation. PBFT is based on a fusion reaction between protons and boron. Three alpha particles are emitted from this reaction. The three alpha particles cause greater damage to tumor cells than the single alpha particle produced in the boron neutron capture reaction or conventional therapy. In addition, the intrinsic proton dose pattern follows Bragg-peak curve. We confirmed an energy deposition by the alpha particle and verified the therapeutic effect of the PBFT.     

Dual-Gate Multiple-Channel ZnO Nanowire Transistors

We report on conventional multichannel ZnO nanowire field-effect transistors (FETs) operating in one device in a dual-gate mode. Our FETs were prepared by assembling ZnO nanowires on a Si substrate using an optimized dielectrophoresis technique with bottom-gate and top-gate FET structures. We observed that the enhancement of the electrical characteristics in FETs with top-gate mode operation results from a thinner gate oxide and top-gate geometry compared with FETs with bottom-gate mode operation. It was also verified that surface passivation strongly affected the electrical performance of ZnO nanowire FETs.     

Monodisperse micron-sized macroporous poly(styrene-co-divinylbenzene) particles by seeded polymerization

Macroporous poly(styrene-co-divinylbenzene) particles were produced in a micron-size range by two-stage swelling and continuous polymerization. The molecular weight of the polystyrene seed particles was controlled by incorporating a urethane acrylate. It was found that the porosity of the particles produced by the seeded polymerization was dependent on the molecular weight of the seed polymer. As the molecular weight of the polystyrene seed increased, the porous particles produced became macroporous. Interestingly, the high molecular weight of the polystyrene seed had a negligible influence on the change of porosity of the seeded polymerized particles. It is believed that the viscosity of the swollen droplet phase remained pretty high with the change in composition because the polystyrene seed copolymerized with urethane cacrylate had many side chains. Received: 16 December 1999 Accepted: 9 August 2000     

Robust and recoverable dual cross-linking networks in pressure-sensitive adhesives

Pressure-sensitive adhesives (PSAs) demand the ability to simultaneously improve toughness and adhesion. However, these requirements of PSAs have remained a great challenge because robust and recoverable characteristics are usually contradictory properties of PSAs. Dual cross-linking networks developed by incorporating dynamic noncovalent bonds into chemical cross-linking networks have the potential to mitigate these requirements in a wide variety of applications including adhesives, hydrogels, and elastomers. Herein, a facile approach to achieve dual cross-linking networks of acrylic PSAs with excellent mechanical properties and high-adhesive performance that integrate physically cross-linked networks into chemically cross-linked networks is proposed. Diurethane acrylic monomer-pentaerythritol ethoxylate (DAM-PEEL) groups were introduced into the acrylic PSA system through photopolymerization. The PSA/DAM-PEEL dual cross-linking networks led to the development of the chemically cross-linked networks for both PSA and DAM via covalent bonds and the physically cross-linked networks between the amide groups of DAM and the hydroxyl groups of PEEL via hydrogen bonds. Consequently, the PSA/DAM-PEEL dual cross-linking networks were able to simultaneously improve the modulus and stretchability. This design strategy for developing dual cross-linking networks of materials could offer potential applications for various adhesive-related applications.     

An Ultraflexible and Stretchable Aptameric Graphene Nanosensor for Biomarker Detection and Monitoring

An ultraflexible and stretchable field‐effect transistor nanosensor is presented that uses aptamer‐functionalized monolayer graphene as the conducting channel. Specific binding of the aptamer with the target biomarker induces a change in the carrier concentration of the graphene, which is measured to determine the biomarker concentration. Based on a Mylar substrate that is only 2.5‐µm thick, the nanosensor is capable of conforming to underlying surfaces (e.g., those of human tissue or skin) that undergo large bending, twisting, and stretching deformations. In experimental testing, the device is rolled on cylindrical surfaces with radii down to 40 µm, twisted by angles ranging from ?180° to 180°, or stretched by extensions up to 125%. With these large deformations applied either cyclically or non‐recurrently, the device is shown to incur no visible mechanical damage, maintain consistent electrical properties, and allow detection of TNF‐α, an inflammatory cytokine biomarker, with consistently high selectivity and low limit of detection (down to 5 × 10^?12 m ). The nanosensor can thus potentially enable consistent and reliable detection of liquid‐borne biomarkers on human skin or tissue surfaces that undergo large mechanical deformations.     

Complex projective towers and their cohomological rigidity up to dimension six

A complex projective tower, or simply a ?P-tower, is an iterated complex projective fibration starting from a point. In this paper we classify all six-dimensional ?P-towers up to diffeomorphism, and as a consequence we show that all such manifolds are cohomologically rigid, i.e., they are completely determined up to diffeomorphism by their cohomology rings.     

Graphene-induced apoptosis in lung epithelial cells through EGFR

Expanding interest in nanotechnology applied to electronic and biomedical fields has led to fast-growing development of various nanomaterials. Graphene is a single-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms with unique physical and chemical properties. Recently, graphene has been used in many studies on electronics, photonics, composite materials, energy generation and storage, sensors, and biomedicine. However, the current health risk assessment for graphene has been relatively limited and inconclusive. This study evaluated the toxicity effects of graphene on the airway epithelial cell line BEAS-2B, which represents the first barrier of the human body to interact with airborne graphene particles. Our result showed that graphene can induce the cellular Ca²⁺ by phospholipase C (PLC) associated pathway by activating epidermal growth factor receptor (EGFR). Subsequently, inositol 1,4,5-triphosphate (IP₃) receptors activate the release of Ca²⁺ from the endoplasmic reticulum (ER) Ca²⁺ stores. Those Ca²⁺ signals further trigger the calcium-regulated apoptosis in the cell. Furthermore, the stimulation can cause EGFR upregulation, which have been demonstrated to associate with diseases such as lung cancer, chronic obstructive pulmonary disease (COPD), and cardiovascular diseases. This study highlights the additional health risk considering that it can function as a contributing factor for other respiratory diseases.     

Thiolated dextran-coated gold nanorods for photothermal ablation of inflammatory macrophages

Thiolated dextran-coated gold nanorods (DEX-GNRs) were synthesized for targeted delivery to inflammatory macrophages and their photothermal ablation under near-infrared (NIR) light irradiation. Successful synthesis of DEX-GNRs was achieved using thiolated dextran, generated by applying mercaptopropionic acid to transform a hydroxyl group of dextran into a thiol group which has strong binding affinity with surfaces of GNRs. We confirmed both the existence of a thiol group in the functionalized dextran using Ellman's reagent in a thiol group assay and the characteristic band of DEX-GNRs using FT-IR spectrum. Furthermore, a cellular uptake study revealed that dextran showed a superior ability to bind the GNRs surface against macrophages compared to those of PEGylated GNRs with various molecular weights of polyethyleneglycol (PEG). Consequently, an in vitro photothermal irradiation experiment using NIR light indicated that DEX-GNRs exhibited a significant cell-killing efficacy, even with a lower concentration of Au and a low-power light source.     

Post‐Synthetic Reversible Incorporation of Organic Linkers into Porous Metal–Organic Frameworks through Single‐Crystal‐to‐Single‐Crystal Transformations and Modification of Gas‐Sorption Properties

The porous metal–organic framework (MOF) {[Zn₂(TCPBDA)(H₂O)₂]?30 DMF?6 H₂O}_n ( SNU‐30 ; DMF=N,N‐dimethylformamide) has been prepared by the solvothermal reaction of N,N,N′,N′‐tetrakis(4‐carboxyphenyl)biphenyl‐4,4′‐diamine (H₄TCPBDA) and Zn(NO₃)₂?6 H₂O in DMF/tBuOH. The post‐synthetic modification of SNU‐30 by the insertion of 3,6‐di(4‐pyridyl)‐1,2,4,5‐tetrazine (bpta) affords single‐crystalline {[Zn₂(TCPBDA)(bpta)]?23 DMF?4 H₂O}_n ( SNU‐31 SC ), in which channels are divided by the bpta linkers. Interestingly, unlike its pristine form, the bridging bpta ligand in the MOF is bent due to steric constraints. SNU‐31 can be also prepared through a one‐pot solvothermal synthesis from Zn^II, TCPBDA^4?, and bpta. The bpta linker can be liberated from this MOF by immersion in N,N‐diethylformamide (DEF) to afford the single‐crystalline SNU‐30 SC , which is structurally similar to SNU‐30 . This phenomenon of reversible insertion and removal of the bridging ligand while preserving the single crystallinity is unprecedented in MOFs. Desolvated solid SNU‐30′ adsorbs N₂, O₂, H₂, CO₂, and CH₄ gases, whereas desolvated SNU‐31′ exhibits selective adsorption of CO₂ over N₂, O₂, H₂, and CH₄, thus demonstrating that the gas adsorption properties of MOF can be modified by post‐synthetic insertion/removal of a bridging ligand.     

Mn-mediated coupling of alkyl iodides and chiral N-acylhydrazones: optimization, scope, and evidence for a radical mechanism

Stereoselective radical additions have excellent potential as mild, nonbasic carbon-carbon bond constructions for direct asymmetric amine synthesis. Efficient intermolecular radical addition to C=N bonds with acyclic stereocontrol has previously been limited mainly to secondary and tertiary radicals, a serious limitation from the perspective of synthetic applications. Here, we provide full details of the use of photolysis with manganese carbonyl to mediate stereoselective intermolecular radical addition to N-acylhydrazones. Photolysis (300 nm) of alkyl halides and hydrazones in the presence of Mn2(CO)10 and InCl(3) as a Lewis acid led to reductive radical addition; diastereomer ratios ranged from 93:7 to 98:2 at ca. 35 degrees C. The reaction tolerates additional functionality in either reactant, enabling subsequent transformations as shown in an efficient asymmetric synthesis of coniine. A series of hydrazones bearing different substituents on the oxazolidinone auxiliary were compared; consistently high diastereocontrol revealed that the identity of the substituent had little practical effect on the diastereoselectivity. Further mechanistic control experiments confirmed the intermediacy of radicals and showed that independently prepared alkyl- or acylmanganese pentacarbonyl compounds do not undergo efficient addition to the N-acylhydrazones under thermal or photolytic (300 nm) conditions. These Mn-mediated conditions avoid toxic tin reagents and enable stereoselective intermolecular radical additions to C=N bonds with the broadest range of alkyl halides yet reported, including previously ineffective primary alkyl halides.