A Hydrogen Peroxide Activatable Gemcitabine Prodrug for the Selective Treatment of Pancreatic Ductal Adenocarcinoma

The main concern in the use of anticancer chemotherapeutic drugs is host toxicity. Patients need to interrupt or change chemotherapy due to adverse effects. In this study, we aimed to decrease adverse events with gemcitabine (GEM) in the treatment of pancreatic ductal adenocarcinoma and focused on the difference of hydrogen peroxide levels in normal versus cancer cells. We designed and synthesized a novel boronate-ester-caged prodrug that is activated by the high H₂O₂ concentrations found in cancer cells to release GEM. An H₂O₂-activatable GEM (A-GEM) has higher selectivity for H₂O₂ over other reactive oxygen species (ROS) and cytotoxic effects corresponding to the H₂O₂ concentration in vitro. A xenograft model of immunodeficient mice indicated that the effect of A-GEM was not inferior to that of GEM when administered in vivo. In particular, myelosuppression was significantly decreased following A-GEM treatment compared with that following GEM treatment.     

Treatment of Single or Multiple Brain Metastases by Hypofractionated Stereotactic Radiotherapy Using Helical Tomotherapy

This study investigated the clinical outcomes of a 4-fraction stereotactic radiotherapy (SRT) study using helical tomotherapy for brain metastases. Between August 2009 and June 2013, 54 patients with a total of 128 brain metastases underwent SRT using tomotherapy. A total dose of 28 or 28.8 Gy at 80% isodose was administered in 4 fractions for all tumors. The mean gross tumor volume (GTV) was 1.9 cc. Local control (LC) rates at 6, 12, and 18 months were 96%, 91%, and 88%, respectively. The 12-month LC rates for tumors with GTV ≤0.25, >0.25 and ≤1, and >1 cc were 98%, 82%, and 93%, respectively; the rates were 92% for tumors >3 cc and 100% for >10 cc. The 6-month rates for freedom from distant brain failure were 57%, 71%, and 55% for patients with 1, 2, and ≥3 brain metastases, respectively. No differences were significant. No major complications were observed. The 4-fraction SRT protocol provided excellent tumor control with minimal toxicity. Distant brain failure was not so frequent, even in patients with multiple tumors. The results of the current study warrant a prospective randomized study comparing single-fraction stereotactic radiosurgery (SRS) with SRT in this patient population.     

A solid–solid extraction

When a vessel containing two equal-sized particle species is subjected to vibration with an acceleration significantly greater than 1g, the particle bed sometimes separates into two clear-cut layers, the bottom layer consisting only of the lighter particles. This paper shows that the above inverse density segregation can be used to perform a solid–solid extraction. A mixture of equal-sized glass and steel beads (1290 μm in mean diameter) did not separate into two layers under vibration. However, when equal-sized lead beads were added to the mixture and the three-component mixture was subjected to vibration the bed separated into two clear-cut layers, the top layer being the mixture of the three components, the bottom layer consisting only of glass beads. The scale effect and the underlying mechanisms of this solid–solid extraction are discussed.     

Self-healing behavior and strength recovery of ytterbium disilicate ceramic reinforced with silicon carbide nanofillers

Environmental barrier coatings (EBCs) are necessary to protect SiC/SiC ceramic components against oxidation and hot corrosion in high-temperature applications. The volatilization of SiO₂ in SiC-reinforced materials is a major obstacle for the implementation of these self-crack-healing ceramics. The Yb₂Si₂O₇-Yb₂SiO₅-SiC composite is known as a self-healing material that can help to avoid this SiC recession. In this research, the crack-healing behavior of this composite is investigated by using pre-cracking followed by annealing in an oxidizing environment. The crack-healing mechanism is explored and elucidated as a function of the filler morphology, crack size, annealing time, and annealing temperature. The two main crack-healing mechanisms are the filling of cracks with SiO₂ glass and the volume expansion of Yb₂Si₂O₇ induced by the reaction between SiO₂ and Yb₂SiO₅. Full crack recovery is achieved with only 10 vol% SiC, with evidence from XRD and EDS analyses. SiC nanoparticulates are more efficient fillers than nanofibers and nanowhiskers.     

Biodegradation of quinoline in crude oil

Removal of quinoline, which is typical of nitrogen‐containing compounds in crude oil, was achieved by a biodegradation reaction by Comamonas sp TKV3‐2‐1. The aerobic strain, Comamonas sp TKV3‐2‐1, which can grow utilizing quinoline as the sources of both carbon and nitrogen, degraded quinoline to 2‐hydroxyquinoline, finally to water‐soluble substances. The degradation reaction of 2‐hydroxyquinoline was revealed to be regarded as a rate‐limiting step controlling the overall reaction of biodenitrogenation process of quinoline in crude oil. The degradation rate of 2‐hydroxyquinoline in a stirred fermenter had a maximum of 211 mg 2‐hydroxyquinoline g‐cell^?1 h^?1 when the portion of crude oil in the reaction mixture, the cell concentration and the rotational speed of agitation impeller were 83.3%(v/v), 28.5 gdm^?3 and 11.7 s^?1, respectively. After the reaction was completed, the crude oil and the cell suspension could be separated efficiently by centrifuging. The possibility of constructing a bioprocess for removing quinoline in crude oil under storage is also discussed. © 2001 Society of Chemical Industry     

A Fast Dynamically Equilibrated Walking Trajectory Generation Method of Humanoid Robot

This paper describes a fast dynamically equilibrated trajectory generation method for a humanoid robot. From a given input motion and the desired ZMP trajectory, the algorithm generates a dynamically equilibrated trajectory using the relationship between the robot's center of gravity and the ZMP. Three key issues are denoted: 1) an enhanced ZMP constraint which enables the calculation of robot stability even if several limbs are contacting the environment, 2) a simplified robot model is introduced that represents the relationship between its center of gravity and ZMP, 3) a convergence method is adopted to eliminate approximation errors arising from the simplified model. Combining these three key issues together with online ZMP compensation method, humanoid robot H5 have succeeded to walk, step down and so on. Experimental results using humanoid robot H5 are described.     

Trichloroethylene transformation by natural mineral pyrite: the deciding role of oxygen

The transformation of trichloroethylene (TCE) in natural mineral iron disulfide (pyrite) aqueous suspension under different oxygen conditions was investigated in laboratory batch experiments. TCE transformation was pursued by monitoring its disappearance and products released with time. The effect of oxygen was studied by varying the initial dissolved oxygen concentration (DO(i)) inside each reactor. Transformation rates depended strongly on DO(i) in the system. In anaerobic pyrite suspension, TCE did not transform as it did under aerobic conditions. The transformation rate increased with an increase in DO(i). The TCE transformation kinetics was fitted to a pseudo-first-order reaction with a rate constant k (h(-1)) varying from 0.004 to 0.013 for closed systems with DO(i) varying from 0.017 to 0.268 mmol/L under the experimental conditions. In the aerobic systems, TCE transformed to several organic acids including dichloroacetic acid, glyoxylic acid, oxalic acid, formic acid, and finally to CO2 and chloride ion. Dichloroacetic acid was the only chlorinated intermediate found. Both TCE and the pyrite surface were oxidized in the presence of O2. Oxygen consumption profiles showed O2 was the common oxidant in both TCE and pyrite oxidation reactions. Ferric ion cannot be used as an alternative oxidant to oxygen for TCE transformation.     

Structural characterization and photocatalytic activity of ultrathin TiO2 films fabricated by Langmuir-Blodgett technique with octadecylamine

TiO₂ thin films with nanometer-scale thicknesses were prepared by the hydrolysis of titanium potassium oxalate using octadecylamine (ODA) Langmuir-Blodgett (LB) films as templates. After optimizing conditions in immersion process, the amount of TiO₂ generated in the ODA LB film was found to be precisely controlled by the number of deposited ODA layers. Morphological measurements showed that uniform TiO₂ film with surface roughness of less than 1.3 nm could be prepared from the monolayer LB films through subsequent heat-treatment process, while generation of cracks became less noticeable on the 5-layer film after heat-treatment at lower holding temperature with slow heating rate. In addition, photocatalytic activities of the TiO₂ films were examined from the decomposition of cadmium stearate (CdSt) LB films and stearic acid (SA) cast films for different time intervals of irradiation with UV light. Atomic force microscopy measurements showed that an almost flat surface of the CdSt LB film changes to a moth-eaten appearance as a result of decomposition under UV light irradiation. Furthermore, the post-heat-treatment at higher temperatures resulted in decreased photocatalytic activity of the TiO₂ film for the decomposition of SA cast film.     

A new concept in high performance ceria–zirconia oxygen storage capacity material with Al2O3 as a diffusion barrier

CeO₂–ZrO₂ solid solution ((Ce,Zr)O₂) is an indispensable oxygen storage capacity (OSC) material for emission control in gasoline-fuelled automobiles. The high performance OSC material developed in this study is composed of Al₂O₃ as “a diffusion barrier” and (Ce,Zr)O₂ particles in intervening layers on a nanometer scale, and is abbreviated as “ACZ”. The Brunauer–Emmett–Teller (BET) specific surface area (SSA) of ACZ after durability testing in air at 1000 °C was 20 m²/g, which is higher than that of conventional CZ (2 m²/g) composed of (Ce,Zr)O₂ without Al₂O₃. After heat treatment at 1000 °C in air, the particle size of (Ce,Zr)O₂ in ACZ was about 10 nm and that without Al₂O₃ was one-half of the size in pure CZ. The OSC was roughly characterized by the total capacity (OSC-c1) and the oxygen release rate (OSC-r). In a fresh catalyst, ACZ and CZ had almost the same OSC-c1; however, the OSC-r of ACZ was twice as fast as CZ. After durability testing, the OSC-r of both ACZ and CZ were reduced significantly, but the OSC-r of ACZ was about five times as fast as CZ. While the OSC-c1 was hardly influenced by the (Ce,Zr)O₂ crystallite size and Pt particle size on the supports, the OSC-r was influenced by both of these parameters. The improvement of the OSC-r in the fresh catalyst and inhibition of the decrease in the OSC-r after durability testing were achieved by suppression of particle growth of (Ce,Zr)O₂ in ACZ by introducing Al₂O₃ as a diffusion barrier with resultant inhibition of sintering of Pt particles.     

Generation of multihollow structured poly(methyl methacrylate) fibers by electrospinning under pressurized CO2

Electrospinning is one of the simple techniques for the production of polymer nano‐microfibers. In this study, hollow fibers from poly(methyl methacrylate) (PMMA) were formed by electrospinning under pressurized carbon dioxide (CO₂) in a single processing step. The experiments were conducted at temperatures and pressures in the range 27–37°C and 4–6 MPa, respectively. At 5 MPa, CO₂ seemed to have enough affinity to dissolve a portion of dichloromethane (DCM) to assist its evaporation. Under subcritical CO₂, electrospun products with hollow core fibers having diameters of 4–16 μm were generated. The results confirmed that the change of operating parameters had a strong influence on the morphologies (crack or hollows) of the electrospun products. This study demonstrated that this process offers the possibility that electrospinning under pressurized CO₂ will become an essential and useful method for the generation of polymer structures with hollow interiors. POLYM. ENG. SCI., 56:752–759, 2016. © 2016 Society of Plastics Engineers