The Critical Role of Passive Permeability in Designing Successful Drugs

Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients.     

Posture Control for Personal Mobility Robot Using Feedback Compensation with Unstable Pole

This paper presents a novel posture control approach using feedback compensation with an unstable pole. For a narrow and small personal mobility robot (PMR), this is needed in order to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) does not settle to the desired point in the following cases: an unknown disturbance force given to the PMR, a fluctuation in the center of gravity of the PMR, and a change in the conditions between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP in the steady state. The proposed controller changes the control input for the actuator of posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified through experiments using a prototype of the PMR.     

Improvement in impact strength of modified cardanol‐bonded cellulose thermoplastic resin by adding modified silicones

The impact strength of cellulose diacetate (CDA) bonded with a modified cardanol (3‐pentadecylphenoxy acetic acid: PAA) was greatly improved up to 9 kJ/m² by adding a relatively small amount of modified silicones while suppressing a decrease in bending strength. In our recent research, this thermoplastic resin (PAA‐bonded CDA) exhibited high rigidity, glass transition temperature, and water resistance. However, its impact strength was insufficient for use in durable products. Therefore, silicones modified with polyether, amino, and epoxy groups were investigated as possible ways to improve the impact strength. The results show that adding polyether‐modified silicone (polyether silicone) with moderate polarity relative to PAA‐bonded CDA resulted in shearing deformation greatly enhances its impact strength while maintaining other properties, including glass transition temperature (T_g), water resistance, and thermoplasticity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40366.     

Improvement in impact strength of modified cardanol‐bonded cellulose thermoplastic resin by using olefin resins

Impact strength of a modified cardanol‐bonded cellulose thermoplastic resin was greatly improved by using a small amount of olefin resins. As we showed, this thermoplastic resin (3‐pentadecylphenoxy acetic acid (PAA)‐bonded cellulose diacetate (CDA): PAA‐bonded CDA) exhibited high practical properties such as bending strength, heat resistance, and water resistance. However, its impact strength was insufficient for use in durable products. We improved the impact strength of PAA‐bonded CDA by adding hydrophobic olefin resins, such as polyethylene or polypropylene, while maintaining good bending strength and breaking strain. Furthermore, the application of olefin resins also increased water resistance and fluidity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39829.     

Improving the gas recovery and separation efficiency of a hydrate-based gas separation

Efficient gas recovery and separation in a hydrate-based system was investigated for a model gaseous mixture of R22 and nitrogen. The formed hydrate settled in the recovery vessel; excess water was recycled and the hydrate was subsequently decomposed by releasing pressure from the vessel. The gas uptake rate of R22 gas from the vapor phase and the gas recovery rate from the hydrate were determined from hydrate formation and decomposition, respectively. The gas recovery rate of R22 gas gradually increased with time. On the contrary, the nitrogen gas recovery rate was a maximum in the initial stage of hydrate decomposition. A high separation factor (S.F.) was achieved by first separating the N₂-rich gas generated during initial hydrate decomposition. An efficient hydrate-based gas separation and recovery process is proposed.     

Fabrication and characterization of poly‐γ‐glutamic acid nanofiber

Poly‐γ‐glutamic acid (γ‐PGA) is a natural polymer that is widely recognized as a component in the viscous filaments of fermented soybean (natto). γ‐PGA is known for its superior biodegradability, biocompatibility and water retention characteristics. Crosslinked γ‐PGA is commonly used as a hydrogel, but it is not used in the fiber form because it is soluble in water. In this study, we demonstrate the use of γ‐PGA‐Na for production of water insoluble γ‐PGA nanofibers by electrospinning. This result was accomplished using an aqueous solvent containing 10 wt % of an oxazoline component polymer as the crosslinking agent and by heat treatment. The crosslinking reaction was evaluated by solid‐state NMR. The nanofiber webs showed a high level of moisture absorption capability while retaining their fibrous shape. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improving the photovoltaic performance of co‐evaporated Cu2ZnSnS4 thin‐film solar cells by incorporation of sodium from NaF layers

We have investigated the influence of sodium (Na) on the properties of co‐evaporated Cu₂ZnSnS₄ (CZTS) layer microstructures and solar cells. The photovoltaic performance and diode properties were improved by incorporating Na from NaF layers into the CZTS layers, while Na had a negligible effect on the microstructural properties of the layer. The best cell fabricated by using an optimal CZTS layer (Cu/(Zn + Sn) = 0.70, Zn/Sn = 1.8) yielded an active area efficiency of 5.23%. The analysis of device properties suggests that charge‐carrier recombination at CZTS/CdS interface is suppressed by intentional Na incorporation from NaF layers. Copyright © 2016 John Wiley & Sons, Ltd.